Abstract:
An unbalance correction device of a high speed rotary apparatus which can prevent the lowering of productivity in the production line of a high speed rotary apparatus while reducing variation in the posture of a workpiece supported by a jig and suppressing vibration of a member (clamp member) for securing the workpiece to the jig, and can enhance the precision of unbalance correction. The unbalance correction device ( 1 ) of a high speed rotary apparatus includes a plurality of claw structures ( 10 ) (clamp members) for fixing, by clamping, a workpiece ( 20 ) to a turbine housing section ( 3 ); a cylinder mechanism ( 30 ) for moving and energizing the claw structures ( 10 ), a solenoid valve ( 35 ) for adjusting the moving amount and energizing force of the claw structure ( 10 ) by the cylinder mechanism ( 30 ); a position sensor ( 37 ) for detecting the position of the claw structure ( 10 ); and posture control means for controlling each solenoid valve ( 35 ) such that the position shift of the claw structure ( 10 ) detected by the position sensor ( 37 ) becomes smaller than its acceptable value.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for correcting an unbalance of a high-speed rotary apparatus used for correcting the unbalance of a rotating portion thereof, with reference to the high-speed rotary apparatus having the rotating portion that rotates at relatively high speed, such as a turbocharger provided with, for example, an automobile engine. 
     RELATED ART 
     In a high-speed rotary apparatus having a rotating portion which rotates at relatively high speed, when residual unbalance in the rotating portion thereof (unbalance remaining after machining or assembling components of the rotating portion) is large, the rotating portion fluctuates too much with rotation thereof, so that troubles such as fluctuation of a housing around the rotating portion or a corresponding noise may be caused. As an example of such high-speed rotary apparatus, there is a turbocharger provided with an automobile engine. In the turbocharger, for example, the rotation number of the rotating portion thereof may amount to 150,000 rpm or more. Thus, when the residual unbalance of the rotating portion in the turbocharger is large, phenomenon such as burn-in of bearing at a bearing portion supporting the rotating portion may be generated, besides the above-mentioned troubles, due to the too much fluctuation of the rotating portion. 
     In this regard, for example, in the turbocharger, a mechanism for generating the troubles due to the unbalance in the high-speed rotary apparatus will be described, with reference to  FIG. 17 . 
     A turbocharger  102  includes a rotating portion. The rotating portion has a rotating shaft  121 , a turbine rotor  122  provided on one end (on the left end in  FIG. 17 ) of the rotating shaft  121 , a compressor rotor  123  provided on the other end (the right end in  FIG. 17 ) of the rotating shaft  121 . In other words, the rotating portion in the turbocharger  102  is a rotating body comprising of the rotating shaft  121 , the turbine rotor  122  and the compressor rotor  123 , which integrally rotate. 
     The rotating shaft  121  is rotatably supported on a center housing  124 . The rotating shaft  121  is supported via two bearings  125  provided on the center housing  124 . In other words, the bearings  125  are interposed between the rotating shaft  121  and the center housing  124 . The turbine rotor  122  is incorporated into a turbine housing  126  attached to one side (the left side in  FIG. 17 ) of the center housing  124 . Incidentally, although not shown in the figure, when the turbocharger  102  is actually used as a product, the compressor rotor  123  is incorporated into a compressor housing mounted on the other side (the right side in  FIG. 17 ) of the center housing  124 . 
     Due to the turbocharger  102  including the above-described construction, the exhaust air from the engine is recovered and compressed, so that it is supplied to the engine as an intake air once again. Briefly, in the turbocharger  102 , the turbine rotor  122  in the turbine housing  126  is rotated with the exhaust air from the engine. The compressor rotor  123  is rotated via the rotating shaft  121  with rotation of the turbine rotor  122 . The exhaust air from the engine, which is recovered in the turbocharger  102 , is compressed and supplied to the engine as the intake air once again, with rotation of the compressor rotor  123 . 
     In the turbocharger  102  including the above-described construction, as shown in  FIG. 17  ( a ), it would be assumed that unbalance having a mass m exists at a position of distance r from the rotating shaft line C of the rotating portion (of the rotating shaft  121 ) in the rotating portion, for example, due to an unbalance portion  127  in the compressor rotor  123 . In this case, due to the rotation of the rotating portion (the rotating body comprising of the rotating shaft  121 , the turbine rotor  122  and the compressor rotor  123 ), the bearings  125  receive reaction forces of mr ω 2 as centrifugal forces from the rotating shaft  121  (see  FIG. 17  ( b )). 
     The reaction force that the bearings  125  received from the rotating shaft  121  is transmitted to the center housing  124  (see  FIG. 17  ( c )). In the center housing  124 , the fluctuation is generated due to the forces received via the bearings  125 . The fluctuation in the center housing  124  is transmitted to the turbine housing  126  (see  FIG. 17  ( d )). In this respect, in the turbocharger  102 , as shown in  FIG. 17  ( d ), the center housing  124  and the turbine housing  126  are fastened and fixed using bolts  128 . Consequently, a good fluctuation transmissibility can be achieved between the center housing  124  and the turbine housing  126 , so that the fluctuation generated due to the unbalance in the rotating portion as a shaking origin is easy to be transmitted to the turbine housing  126 . Incidentally, the bolts  128  are threaded into the turbine housing  126  via a flange portion  124   a  formed on the end portion of the center housing  124 . Accordingly, the noise in the turbocharger  102  is generated due to the fluctuation of the turbine housing  126  accompanying the rotation of the rotating portion. 
     Thus, in the turbocharger  102 , the trouble as the noise with the fluctuation of the turbine housing  126  is caused, due to the unbalance of the rotating portion. 
     The fluctuation in the turbine housing  126  has a high correlation with the noise in the vehicle such as the automobile equipped with the engine having the turbocharger  102 . For this reason, reducing the fluctuation in the turbine housing  126  is defined as an intermediate characteristic on lowering the noise in the turbocharger  102 . Specifically, in the turbocharger  102 , the unbalance in the rotating portion is corrected, and the fluctuation in the turbine housing  126  is restrained, so that the noise generated in the turbocharger  102  is reduced. 
     In this regard, in the high-speed rotary apparatus such as the turbocharger, the correction for the unbalance in the rotating portion is performed, so as to prevent the trouble due to the residual unbalance in the rotating portion (for example, see JP2002-39904). An example of the unbalance correction, for example, in case of the aforementioned turbocharger  102  as the high-speed rotary apparatus will be described, with reference to  FIG. 18 . 
     An unbalance correction device is utilized for correcting the unbalance in the turbocharger  102 . In the unbalance correction device, a turbine housing portion  103  is provided on a mounting having vibration-proofing support or the like, as a jigupporting the turbocharger  102 . The turbine housing portion  103  is comprised of the member corresponding to the turbine housing  126  (see  FIG. 17 ) in the turbocharger  102  as a product. The construction, (hereinafter, referred to as “a work  120 ”) including the rotating portion (the rotating body comprising of the rotating shaft  121 , the turbine rotor  122  and the compressor rotor  123 ) in the turbocharger  102 , as well as the center housing  124 , is attached to the turbine housing portion  103 . When the work  120  is attached to the turbine housing portion  103 , the center housing  124  is fixed at the turbine housing portion  103 . The unbalance correction device is provided at the given position thereof (for example, at the turbine housing portion  103 ) with an acceleration pickup as a fluctuation detecting means. 
     With the work  120  attached to the turbine housing portion  103 , the same air as the exhaust air from the engine (a compressed air having a pressure corresponding to the exhaust air pressure) is supplied from the air source to the turbine housing portion  103 , whereby the rotating portion including the turbine rotor  122  is rotated via the rotor  122 . 
     In case of the unbalance correction, the rotating portion of the work  120  (hereinafter, referred to as “a work rotating portion”) is rotated at the predetermined rotation number (for example, 70,000 rpm, hereinafter, referred to as “an unbalance correction rotation number). In other words, the vibrational acceleration on condition that the work rotating portion rotates at the unbalance correction rotation number is detected by the acceleration pickup. The unbalance in the work rotating portion is measured, based on the value of the detected vibrational acceleration. 
     The unbalance in the work rotating portion is corrected, based on the measured value of the unbalance. The correction for the unbalance in the work rotating portion is performed by grinding the given portion such as a portion of a nut used for fixing the compressor rotor  123  to the rotating shaft  121  using a grinding machine, for example, in the work rotating portion. 
     With respect to the unbalance correction for the turbocharger  102  performed using the above-mentioned method, it is conceivable that a bolt fastening is utilized for fixing the work  120  (the center housing  124 ) on the turbine housing portion  103 , as is the case with fixing the center housing  124  in the turbocharger  102  as the product on the turbine housing  126  (see  FIG. 17  ( d )). 
     However, fixing the work  120  to the jig (the turbine housing portion  103 ) for the unbalance correction in the turbocharger  102  leads to the reduction of the productivity in the production line for the turbocharger  102 . Briefly, it is not preferable from the aspect of the productivity, to fix the work  120  to the jig by fastening plurality of bolts, every time the unbalance correction is performed in the production line for the turbocharger  102 . 
     With respect to the unbalance correction for the turbocharger  102 , a clamp method may be utilized for fixing the work  120  to the jig. The concrete procedure goes as follows. 
     As shown in  FIG. 18 , in the clamp method, a locking pawl  111  is used for fixing the work  120  to the turbine housing portion  103 . Multiple (two in  FIG. 18 ) locking pawls  111  are provided at specified intervals in the rotational direction of the work rotating portion. The flange portion  124   a  of the center housing  124  is clamped toward the turbine housing portion  103  using the locking pawls  111 , so that the work  120  is fixed to the turbine housing portion  103 . Specifically, the locking pawls  111  have a locking portion  113  so as to clamp the flange portion  124   a  of the center housing  124  toward the turbine housing portion  103 . With the locking portion  113  engaged on the flange portion  124   a , the locking pawls  111  is biased toward the direction clamping the flange portion  124   a  of the center housing  124  by the locking portion  113  (the left direction in  FIG. 18 ), so that the center housing  124  is fixed to the turbine housing portion  103 . In this regard, the locking pawls  111  are pulled via a rod portion  112  extending from one end thereof (the left side in  FIG. 18 ), using, for example, a cylinder mechanism, so as to be biased toward the clamping direction. 
     As described above, the following problem is caused, in the unbalance correction device using the clamp method for fixing the work  120  to the jig. 
     In case of the unbalance correction, as mentioned above, the turbine housing portion  103  as the jig is used as a common jig for plurality of works  120 . In the construction that the works  120  are clamped and fixed on the turbine housing portion  103 , there is sometimes variability among the attitudes of the works  120  toward the turbine housing portion  103  (hereinafter, referred to as “a work attitude”), with the works  120  clamped on the turbine housing portion  103  (hereinafter, referred to as “a clamped condition”). 
     Specifically, as shown in  FIG. 18 , the work  120  is supported on the surface portion in the approximately vertical direction of the turbine housing  103 , on the condition that a direction of the rotating shaft line of the work rotating portion thereof becomes the approximately horizontal one (the lateral direction in  FIG. 18 ). Therefore, in the work  120  supported on the turbine housing  103 , the gravity under it&#39;s own weight works in the different direction (the downward direction in  FIG. 18 ) from the supported direction (the left direction  FIG. 18 ). 
     As exaggeratingly shown in  FIG. 19 , the gravity by it&#39;s own weight acting on the work  120  on the clamped condition works so that the work  120  is tilted, with the lower end portion of the flange portion  124   a  in the center housing  124  contacted with the turbine housing  103 . When the working position is tilted, the locking position (the clamped position) of the work  120  (the flange portion  124   a ) by the locking portion  113  of the locking pawl  111  is changed. 
     Due to these action on the work  120  on the clamped condition by the gravity under it&#39;s own weight or the individual difference in the work  120 , the working position on the clamped condition is varied depending on the types of the work  120 . In other words, when the clamping for plurality of works  120  is randomly performed, different works  120  may change the working positions, thereby causing the variations of the working positions between plurality of works  120 . 
     As mentioned above, when the working position is widely varied, the locking position (the clamped position) of the work  120  by the locking pawl  111  is highly variable, thereby causing the variations in the fluctuation of the work  120  itself with rotating of the work rotating portion, the largeness o the vibration transmitted to the acceleration pickup via the turbine housing  103  or the like. Briefly, the variation in the working position causes the lowering of accuracy in the unbalance correction for the work  120 . 
     In the construction that the work  120  is clamped and fixed on the turbine housing  103 , the member clamping the work  120  (the locking pawl  111 ) vibrates relative to the turbine housing  103  (with natural frequency different from the construction including the turbine housing  103 ) (see arrows X 1  and X 2  in  FIG. 18 ). The vibration of the member clamping the work  120  leads to the destabilization of the clamping force, i.e., the force that the work  120  is pressed on the turbine housing  103 . When the clamping force for the work  120  is instable, the work  120  clamped on multiple portions of the turbine housing  103  may be largely vibrated (see an arrow X 3  in  FIG. 18 ), and in some cases, the work  120  on the clamped condition may run wildly. 
     Thus, when the work  120  is largely vibrated, the accurate vibration measurement could not be performed during the unbalance correction, thereby lowering the accuracy in the unbalance correction. In other words, it is preferable that the member clamping the work  120  is prevented from vibrating with rotating the work rotating portion, so as to improve the accuracy in the unbalance correction. 
     It is an object of the prevent invention to provide an unbalance correction device for the high-speed rotary apparatus, which can prevent the lowering of productivity in the production line for the high-speed rotary apparatus, as well as can reduce the positional variations of the works supported by the jig and can restrain the vibration of the member for fixing the work to the jig (the clamping member), so as to improve the accuracy in the unbalance correction. 
     SUMMARY OF THE INVENTION 
     The first aspect of the present invention is a device for correcting an unbalance of a high-speed rotary apparatus, comprising a jig for supporting a work having a rotating portion and including means for detecting vibration, wherein when fixing the work to the jig where the rotating portion being rotatable, the rotating portion rotated at a given rotation number and performing an unbalance correction of the rotating portion, based on a detected value by the detecting means, the device comprising: a plurality of clamping members for clamping and fixing the work on the jig, with being biased in given directions where the work is fixed on the jig in the engaged condition where they are engaged with the work supported by the jig; a plurality of means for moving the clamping members in moving directions including the given directions and for biasing the clamping members on the engaged condition in the given directions, provided with respect to the each clamping members; a plurality of means for adjusting moving amounts of the clamping members in the moving directions by the moving and biasing means and biasing forces for the clamping members in the given directions, provided with respect to the each moving and biasing means; a plurality of means for detecting positions of the clamping members in the moving direction on the engaged condition, provided with respect to the each clamping members; and a plurality of means for controlling each of the adjusting means, such that shifting amounts of the positions in the moving direction of the clamping members, from the predetermined reference positions, on the engaged condition detected by the position detecting means, based on detected signals from the each position detecting means, become smaller than given acceptable values preliminarily determined for the shifting amounts. 
     Preferably, the device further comprises means for detecting displacements of the vibrations in the moving directions of the clamping members clamping the work on the jig with respect to the device body integrally constructed including the jig with the rotation of the rotating portion, provided with respect to the each clamping members; means for switching moving and biasing directions in the moving directions of the clamping members by means of the moving and biasing means, provided with respect to the each moving and biasing means; means for controlling the biasing forces biasing the clamping members by means of the moving and biasing means in the moving and biasing directions of the clamping members defined by the switching means, provided with respect to the each moving and biasing means; means for calculating excitation forces acting on the clamping members in the moving directions with the rotation of the rotating portion, based on the displacements of the clamping members detected by the displacement detecting means, as well as total mass of the clamping members, total damping of the clamping members in the moving directions and total rigidity of the clamping members in the moving directions; means for calculating damping forces acting on the clamping members in an opposite directions and the same sizes to the excitation forces calculated by the excitation force calculating means; and means for controlling the switching means and biasing force controlling means, such that the damping forces calculated by the damping force calculating means act on the clamping members. 
     Preferably, in the device of the present invention, the moving and biasing means is constituted as a fluid pressure cylinder mechanism using magnetic fluid as the working fluid, the device further comprising: means for detecting displacements of the vibrations in the moving directions of the clamping members clamping the work on the jig with respect to the device body integrally constructed including the jig with the rotation of the rotating portion, provided with respect to the each clamping members; means for applying magnetic field to the magnetic fluid, provided with respect to the each moving and biasing means; means for memorizing pre-calculated data for relationship between the total damping and an intensity of the magnetic field applied to the magnetic fluid by the magnetic field applying means; means for calculating the total damping of the clamping members in the moving directions, counteracting the excitation forces acting on the clamping members in the moving directions with the rotation of the rotating portion, based on the displacements of the clamping members detected by the displacement detecting means, as well as the total mass of the clamping members and the total rigidity of the clamping members in the moving directions; and means for controlling the magnetic field applying means, such that the intensity of the magnetic field applied to the magnetic fluid corresponds to the total damping calculated by the damping calculating means, based on the data memorized by the data memorizing means. 
     The second aspect of the present invention is a device for correcting an unbalance of a high-speed rotary apparatus, comprising a jig for supporting a work having a rotating portion and including means for detecting vibration, wherein when fixing the work to the jig where the rotating portion being rotatable, the rotating portion rotated at a given rotation number and performing an unbalance correction of the rotating portion, based on a detected value by the detecting means, the device comprising: a plurality of clamping members for clamping and fixing the work on the jig, with being biased in given directions where the work is fixed on the jig in the engaged condition where they are engaged with the work supported by the jig; a plurality of means for moving the clamping members in moving directions including the given directions and for biasing the clamping members on the engaged condition in the given directions, provided with respect to the each clamping members; means for detecting displacements of the vibrations in the moving directions of the clamping members clamping the work on the jig with respect to the device body integrally constructed including the jig with the rotation of the rotating portion, provided with respect to the each clamping members; means for switching moving and biasing directions in the moving directions of the clamping members by means of the moving and biasing means, provided with respect to the each moving and biasing means; means for controlling the biasing forces biasing the clamping members by means of the moving and biasing means in the moving and biasing directions of the clamping members defined by the switching means, provided with respect to the each moving and biasing means; means for calculating excitation forces acting on the clamping members in the moving directions with the rotation of the rotating portion, based on the displacements of the clamping members detected by the displacement detecting means, as well as total mass of the clamping members, total damping of the clamping members in the moving directions and total rigidity of the clamping members in the moving directions; means for calculating damping forces acting on the clamping members in an opposite directions and the same sizes to the excitation forces calculated by the excitation force calculating means; and means for controlling the switching means and biasing force controlling means, such that the damping forces calculated by the damping force calculating means act on the clamping members. 
     The third aspect of the present invention is a device for correcting an unbalance of a high-speed rotary apparatus, comprising a jig for supporting a work having a rotating portion and including means for detecting vibration, wherein when fixing the work to the jig where the rotating portion being rotatable, the rotating portion rotated at a given rotation number and performing an unbalance correction of the rotating portion, based on a detected value by the detecting means, the device comprising: a plurality of clamping members for clamping and fixing the work on the jig, with being biased in given directions where the work is fixed on the jig in the engaged condition where they are engaged with the work supported by the jig; a plurality of means for moving the clamping members constituted as a fluid pressure cylinder mechanism using magnetic fluid as the working fluid in moving directions including the given directions and for biasing the clamping members on the engaged condition in the given directions, provided with respect to the each clamping members; means for detecting displacements of the vibrations in the moving directions of the clamping members clamping the work on the jig with respect to the device body integrally constructed including the jig with the rotation of the rotating portion, provided with respect to the each clamping members; means for applying magnetic field to the magnetic fluid, provided with respect to the each moving and biasing means; means for memorizing pre-calculated data for relationship between the total damping and an intensity of the magnetic field applied to the magnetic fluid by the magnetic field applying means; means for calculating the total damping of the clamping members in the moving directions, counteracting the excitation forces acting on the clamping members in the moving directions with the rotation of the rotating portion, based on the displacements of the clamping members detected by the displacement detecting means, as well as the total mass of the clamping members and the total rigidity of the clamping members in the moving directions; and means for controlling the magnetic field applying means, such that the intensity of the magnetic field applied to the magnetic fluid corresponds to the total damping calculated by the damping calculating means, based on the data memorized by the data memorizing means. 
     According to the present invention, the reduction in productivity the reduction of the productivity in the production line of the high-speed rotary apparatus can be prevented, and the variations in the attitudes of the work supported on the jig can be reduced, as well as, the fluctuation of the member (the clamping member) so as to fix the work to the jig can be restrained, thereby improving the accuracy of the unbalance correction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an entire construction of an unbalance correction device according to the first embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of  FIG. 1  along the line A-A. 
         FIG. 3  is a diagram of a controlling construction on the positional control for the unbalance correction device according to the first embodiment of the present invention. 
         FIG. 4  is a flow diagram of the positional control for the work. 
         FIG. 5  is a pattern diagram showing a construction of a pawl structure. 
         FIG. 6  is a diagram of single-degree-of-freedom system model of the respective pawl structure for the device body. 
         FIG. 7  is a diagram showing the respective masses (mass bodied) for modeling the unbalance correction device according to the first embodiment of the present invention. 
         FIG. 8  is a diagram showing the pawl structure. 
         FIG. 9  is a diagram showing a device configuration for damping control of the pawl structure in the unbalance correction device according to the first embodiment of the present invention. 
         FIG. 10  is a diagram showing controlling construction for damping control of the pawl structure in the unbalance correction device according to the first embodiment of the present invention. 
         FIG. 11  is an illustration diagram for a changeover of a flow passage by a solenoid changeover valve. 
         FIG. 12  is a flow diagram of the damping control for the pawl structure according to the first embodiment. 
         FIG. 13  is a diagram showing a device configuration for damping control of the pawl structure in the unbalance correction device according to the second embodiment of the present invention. 
         FIG. 14  is a diagram showing controlling construction for damping control of the pawl structure in the unbalance correction device according to the second embodiment of the present invention. 
         FIG. 15  is a diagram showing an example of a correlation between the current value I for supplying to a cylinder coil and the viscosity μ of a magnetic fluid. 
         FIG. 16  is a flow diagram of the damping control for the pawl structure according to the second embodiment. 
         FIG. 17  is an illustration diagram for a generating mechanism of troubles caused due to the unbalance in a turbocharger. 
         FIG. 18  is a diagram showing the condition of the turbocharger during the unbalance correction. 
         FIG. 19  is a diagram showing the tilt of the working position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An unbalance correction device for a high-speed rotary apparatus according to the present invention is utilized, in the high-speed rotary apparatus having a rotating portion which relatively rotates at high speed, such as a turbocharger provided with an automobile engine, for correcting the unbalance in the rotating portion thereof. 
     Specifically, in the unbalance correction device for the high-speed rotary apparatus, the rotating portion of the high-speed rotary apparatus is rotated at the given rotation number and the vibration acceleration with rotation of the rotating portion thereof is measured. The unbalance in the rotating portion is measured, based on the measured vibration acceleration. The unbalance in the rotating portion of the high-speed rotary apparatus is corrected, based on the measured value of the unbalance. 
     The first embodiment of the unbalance correction device for the high-speed rotary apparatus according to the present invention (hereinafter, simply referred to as “the unbalance correction device” will be described with reference to  FIGS. 1 and 2 . Incidentally, in the present embodiment, the high-speed rotary apparatus that the unbalance is corrected by using the unbalance correction device is defined as the turbocharger provided with the automobile engine. 
     As shown in  FIG. 1 , an unbalance correction device  1  of the present embodiment is used for correcting the unbalance correction of a turbocharger  2 . 
     The turbocharger  2  includes a rotating portion. In the present embodiment, the rotating portion in the turbocharger  2  has a rotating shaft  21 , a turbine rotor  22  provided on one end (on the left end in  FIG. 1 ) of the rotating shaft  21  and a compressor rotor  23  on the other end (on the right end in  FIG. 1 ) of the rotating shaft  21 . In other words, in the present embodiment, the rotating portion in the turbocharger  2  is constituted as a rotating body comprising of the rotating shaft  21 , the turbine rotor  22  and the compressor rotor  23 , which they integrally rotates. 
     The rotating shaft  21  is rotatably supported on a center housing  24  that is approximately cylindrically constructed as a whole. The rotating shaft  21  is supported via a bearing (not shown) on the center housing  24 . 
     When the turbocharger  2  is used as an actual product, the turbine rotor  22  is incorporated into a turbine housing attached to one side (the left side in  FIG. 1 ) of the center housing  24 . Similarly, when the turbocharger  2  is used as the actual product, the compressor rotor  23  is incorporated into a compressor housing attached to the other side (the right side in  FIG. 1 ) of the center housing  24 . 
     Due to the turbocharger  2  including the above-described construction, the exhaust air from the engine is recovered and compressed, so that it is supplied to the engine as an intake air once again. Briefly, in the turbocharger  2 , the turbine rotor  22  in the turbine housing is rotated with the exhaust air from the engine. The compressor rotor  23  in the compressor housing is rotated via the rotating shaft  21  with rotation of the turbine rotor  22 . The exhaust air from the engine, which is recovered in the turbocharger  2 , is compressed and supplied to the engine as the intake air once again, with rotation of the compressor rotor  23 . 
     In the turbocharger  2 , the construction including the rotating portion thereof and the center housing  24  is formed as a work  20  in the unbalance correction device  1 . In other words, the center housing  24 , which rotatably supports the rotating portion having the rotating shaft  21 , the turbine rotor  22  and the compressor rotor  23 , becomes the work  20  in the unbalance correction device  1 . Therefore, the work  20  becomes the turbocharger  2  on the partially assembled condition. The unbalance in the rotating portion of the work  20  is corrected, during the unbalance correction for the turbocharger  2 . 
     Hereinafter, the rotating portion in the turbocharger  2 , i.e., the rotating body comprising of the rotating shaft  21 , the turbine rotor  22  and the compressor rotor  23  is also referred to as “the work rotating portion”. 
     The unbalance correction device  1  of the present embodiment supports the work  20  having the rotating portion and has a turbine housing portion  3 , as a jig having an acceleration pickup  4  as a vibration detecting means. 
     The turbine housing portion  3  is made up of the same member as the turbine housing incorporating the turbine rotor  22  in the turbocharger  2  as the product as described previously. The turbine housing portion  3  is used as a common jig for plurality of works  20  that the unbalance correction is performed by the unbalance correction device  1 . Therefore, in the unbalance correction device  1 , the center housing  24  is supported on the turbine housing portion  3 , so that the work  20  is supported on the turbine housing portion  3 . 
     The turbine housing portion  3  is provided at the predetermined position on a trestle  5 . In the present embodiment, the turbine housing portion  3  is provided on the condition that a direction of the rotating shaft line of the rotating portion in the work  20 , which the turbine housing portion  3  supports, becomes the approximately horizontal one. Therefore, the work  20 , which is supported by the turbine housing portion  3 , is disposed so that the direction of the rotating shaft line of the rotating portion thereof becomes the approximately horizontal one (the lateral direction in  FIG. 1 ). The turbine housing portion  3  is supported and fixed at the predefined position on a supporting wall  6  which is vertically provided on the trestle  5 , whereby it is provided at the given position on the trestle  5   
     The trestle  5  is provided so that it is prevented from vibrating and supported via a rubber mount  8  on a floor surface  7 . The acceleration pickup  4  is provided at the given position on the turbine housing portion  3 . The acceleration pickup  4  is comprised of an acceleration sensor or the like and detects (picks up) the vibration acceleration at the given position of the turbine housing  3 . The unbalance in the work rotating portion is measured, based on the value of the vibration acceleration detected by the acceleration pickup  4   
     In other words, the acceleration pickup  4  is connected to an arithmetic device (not shown), and a detection signal output from the acceleration pickup  4  is input into the arithmetic device. In the arithmetic device, measuring the unbalance and calculation for correcting it in the work  20  is performed. 
     In the unbalance correction device  1 , the work  20  is fixed on the turbine housing portion  3 , with the work rotating portion rotatable, and the work rotating portion is rotated at the predefined rotation number. The unbalance in the work rotating portion is corrected, based on the detected value by the acceleration pickup  4  with the work rotating portion rotated at the predefined rotation number. 
     More specifically, the unbalance correction in the unbalance correction device  1  is performed as follows. 
     In the unbalance correction in the unbalance correction device  1 , first, the work  20  is attached to the turbine housing portion  3 . In the assembly of the work  20  on the turbine housing portion  3 , the center housing  24  is fixed on the turbine housing portion  3 . 
     With the work  20  attached to the turbine housing portion  3 , the same air as the exhaust air from the engine (a compressed air having a pressure corresponding to the exhaust air pressure) is supplied from the air source to the turbine housing portion  3 , whereby the work rotating portion including the turbine rotor  22  is rotated via the rotor  22 . 
     In case of the unbalance correction, the work rotating portion is rotated at the predetermined rotation number (for example, 70,000 rpm, hereinafter, referred to as “an unbalance correction rotation number). In other words, the vibrational acceleration on condition that the work rotating portion rotates at the unbalance correction rotation number is detected by the acceleration pickup  4 . The unbalance in the work rotating portion is measured, based on the value of the detected vibrational acceleration. 
     The unbalance in the work rotating portion is corrected, based on the measured value of the unbalance. The correction for the unbalance in the work rotating portion is performed by grinding the given portion such as a portion of a nut used for fixing the compressor rotor  23  to the rotating shaft  21  using a grinding machine, for example, in the work rotating portion. 
     The unbalance correction device  1  used for correcting the unbalance in the turbocharger  2  as described above includes plurality of pawl structures  10  for fixing the work  20  to the turbine housing portion  3 , during the unbalance correction. The pawl structure  10  is one embodiment of clamping member that clamps and fixes the work  20  on the turbine housing portion  3 . 
     The pawl structure  10  is biased toward the predetermined direction where the work  20  is fixed on the turbine housing portion  3 , on the engaged condition that it is engaged on the work  20  supported on the turbine housing portion  3  (hereinafter, referred to as “the engaged condition”), thereby clamping and fixing the work  20  on the turbine housing portion  3 . 
     In the present embodiment, as shown in  FIG. 1 , the pawl structure  10  has a pawl portion  11  and a rod portion  12 . 
     The pawl portion  11  has a locking portion  13  that locks the work  20  supported on the turbine housing portion  3 . Briefly, in the present embodiment, the locking portion  13  locks the work  20 , so that the pawl structure  10  is on the engaged condition. The locking portion  13  is a plate-like portion which is projected and formed on one end portion (the apical end) of a body portion  11   a  that is comprised in the form of approximately rectangular solid in the pawl portion  11   
     The rod portion  12  is extended from the side that the locking portion  13  is provided in the pawl portion  11  (on the front end side, on the right side in  FIG. 1 ) and from the opposite side thereof (on the rear end portion, on the left side in  FIG. 1 ). The rod portion  12  is constituted as a rod-like portion having a smaller diameter than that of the pawl portion  11 . 
     The work  20  supported on the turbine housing portion  3  is fixed thereon by the pawl structure  10  having above-mentioned construction. 
     The turbine housing portion  3  has a supporting surface  3   a  as the surface in the approximately perpendicular direction to the rotating shaft line of the work rotating portion. The supporting surface  3   a  is formed as the surface of the bottom side (the back side) of a supporting recessed portion  3   b  formed on the side supporting the work  20  on the turbine housing portion  3 . The work  20  is supported on the supporting surface  3   a  of the turbine housing portion  3 . The center housing  24  in the work  20  is provided on one end thereof (on the side to which the turbine housing is attached) with a annular flange portion  24   a . The flange portion  24   a  of the center housing  24  is in contact with the supporting surface  3   a  of the turbine housing portion  3 , with the work  20  supported. In other words, the supporting recessed portion  3   b  in the turbine housing portion  3  has a circular geometry along the shape of the flange portion  24   a  of the center housing  24 , and the flange portion  24   a  contacts the supporting surface  3   a , with a part of the flange portion  24   a  fixed on the supporting recessed portion  3   b . Under the circumstances, the flange portion  24   a  is pressed on the supporting surface  3   a  by the pawl structure  10 , so that the work  20  is fixed on the turbine housing portion  3 . 
     The pawl structure  10  presses the flange portion  24   a  on the supporting surface  3   a  of the turbine housing portion  3 , with the locking portion  13  engaged on the flange portion  24   a  of the center housing  24 . Briefly, the flange portion  24   a  of the center housing  24  in the work  20  works as a portion engaged on the locking portion  13  of the pawl structure  10 . 
     In this regard, in case of pressing the flange portion  24   a  by the locking portion  13 , as described above, the surface on one end of the locking portion  13  as the plate-like portion works as a pressing surface  13   a  to the flange portion  24   a . In other words, the pressing surface  13   a  of the locking portion  13  is formed as the surface parallel to the supporting surface  3   a  of the turbine housing portion  3 . When the work  20  is fixed on the turbine housing portion  3  by the pawl structure  10 , the flange portion  24   a  of the center housing  24  is interposed between the supporting surface  3   a  of the turbine housing portion  3  and the pressing surface  13   a  of the locking portion  13 . In this way, the pressing surface  13   a  contacts the flange portion  24   a , so that the pawl structure  10  is on the engaged condition. 
     Therefore, in the unbalance correction device  1 , the pawl structure  10  is provided so that the pressing surface  13   a  of the locking portion  13  is opposed to the flange portion  24   a  that contacts the supporting surface  3   a  of the turbine housing portion  3 . In the present embodiment, in the unbalance correction device  1 , the pawl structure  10  is provided so that the extending direction of the rod portion  12  is approximately parallel to the direction of the rotating shaft line of the work rotating portion. The pawl structure  10  is provided so that the projecting direction of the locking portion  13  in the pawl portion  11  from the body portion  11   a  is along the radial direction of the work rotating portion (the radial direction of the rotating shaft  21  or the like) (so that the projecting direction is the direction to the rotating shaft line of the work rotating portion. 
     The pawl structure  10  is provided so that the pressing surface  13   a  thereof is movable to the direction moving to or from the flange portion  24   a  (to the lateral direction in  FIG. 1 ). 
     The pawl structure  10  is provided so that it can be biased to the direction pressing the flange portion  24   a  by the locking portion  13 , with the pressing surface  13   a  contacting the flange portion  24   a , i.e., with the locking portion  13  engaged on the work  20 . In other words, in the present embodiment, the pawl structure  10  is provided so that it can be biased in the extending direction of the rod portion  12  from the pawl portion  11  (in the left direction in  FIG. 1 ). 
     Thus, in the present embodiment, the predetermined direction where the work  20  is fixed on the turbine housing portion  3 , to which the pawl structure  10  is biased is the direction where the pawl structure  10  presses the flange portion  24   a  by the pressing surface  13   a  of the locking portion  13 . Hereinafter, the predetermined direction to which the pawl structure  10  is biased is defined as “the work fixing direction”. The moving direction including the work fixing direction as the direction, to which the pawl structure  10  is moved (the direction moving to or from the flange portion  24   a , is simply referred to as “the moving direction”. 
     The biases of the pawl structures  10  toward the work fixing direction are performed by cylinder mechanisms  30 . The cylinder mechanisms  30  are provided in each of plurality of pawl structures  10  equipped with the unbalance correction device  1  as mentioned previously. Specifically, the cylinder mechanisms  30  are provided on the respective pawl structures  10  and functions as moving and biasing means that move the pawl structures  10  to the moving direction and bias the pawl structures  10  on the engaged condition to the work fixing direction. 
     The cylinder mechanisms  30  are constituted as hydraulic cylinders. The cylinder mechanisms  30  have cylinder cases  31  which movably incorporate the rod portions  12  of the pawl structures  10  as cylinder rods. Specifically, the rod portions  12 , which is incorporated into the cylinder cases  31  via the piston portions  14 , have piston portions  14  as diameter expanding portions, and are slidably provided in the cylinder cases  31 . The piston portions  14  are disposed on the side opposite to the side of the pawl portion  11  in the rod portion  12  (on the left side in  FIG. 1 ). The piston portions  14  are plug-like portions having shapes slidable to inner walls of the cylinder cases  31 . 
     The cylinder cases  31  are fixed and supported on cylinder plates  9 . The cylinder plates  9 , which are plate-like members, are fixed on the opposite sides to the sides of the supporting surfaces  3   a  in the turbine housing portions  3 , so that the plate surfaces thereof are the surfaces approximately perpendicular to the directions of the rotating shaft lines of the work rotating portions. The cylinder cases  31  are supported on the plate surface portions on the opposite sides to the sides of the turbine housing portions  3  in the cylinder plates  9 , so that the sliding directions of the rod portions  12  therein are the corresponding ones to the moving directions of the aforementioned pawl structures  10 . 
     Incidentally, through-holes  9   a  are provided so as to allow the movements of the pawl structures  10  in the cylinder plates  9 , with the rod portions  12  penetrating therethrough 
     In the cylinder mechanisms  30  having the above-mentioned construction, the pressure oils having the given pressure are supplied from oil tanks via oil pumps or the like to the cylinder cases  31 , in case of biasing the pawl structures  10  to the work fixing direction. The pawl structures  10  are pulled to the work fixing direction due to the given biasing forces via the piston portions  14 , by adjusting the hydraulic pressure in the cylinder cases  31 . In this way, the pawl structures  10  are biased to the work fixing direction due to the thrust forces in the cylinder mechanisms  30 . Thus, the pawl structures  10  are biased to the work fixing direction, and the flange portions  24   a , which are interposed between the pressing surfaces  13   a  of the locking portions  13  and the supporting surfaces  3   a  of the turbine housing portions  3 , are pressurized so as to contact the supporting surfaces  3   a  by the predefined pressing forces from the locking portions  13 , so that the works  20  are fixed on the turbine housing portions  3 . 
     In this regard, the cylinder mechanisms  30  are constructed as hemi-rod typed double-acting cylinder projecting the rod portions  12  of the pawl structures  10  from one side of the cylinder cases  31 . Briefly, in the cylinder mechanisms  30 , cylinder chambers in the cylinder cases  31  are divided into two cylinder chambers  31   a ,  31   b  via the piston portions  14  of the rod portions  12  in the pawl structures  10 . The respective cylinder chambers  31   a ,  31   b  have doorways for the oils. The doorways for the oils in the respective cylinder chambers alternately become inlets or outlets for the oils by circuit switching such as changeover valves, thereby reciprocating in the moving directions of the pawl structures  10 . 
     Therefore, when the pressure oils are supplied in the cylinder chambers  31  on the projecting sides of the rod portions  12  (the right side in  FIG. 1 ), the pawl structures  10  are pulled, so that the pawl structures  10  are moved to the work fixing directions and accordingly the pawl structures  10  on the engaged condition are biased to the work fixing directions. Meanwhile, when the pressure oils are supplied in cylinder chambers  31   b  on opposite side to the projecting sides of the rod portions  12  (the left side in  FIG. 1 ), the pawl structures  10  are pushed outward, so that the pawl structures  10  are moved to the opposite directions to the work fixing directions and the engaged condition of the pawl structures  10  are canceled (the pawl structures  10  are biased to the opposite directions to the work fixing directions). 
     In the following descriptions, the cylinder chambers  31   a  on the sides that the pawl structures  10  are pulled due to the supplies of the pressure oils (on the projecting side of the rod portions  12 ) are defined as “the first cylinder chambers  31   a ”, and the cylinder chambers  31   b  on the sides that the pawl structures  10  are pushed outward due to the supplies of the pressure oils are defined as “the second cylinder chambers  31   b”.    
     Incidentally, in the unbalance correction device  1  of the present embodiment, the cylinder mechanisms  30  are provided as hydraulic cylinders, but the moving and biasing means, which move the pawl structures  10  to the moving directions and bias the pawl structures  10  on the engaged condition to the work fixing directions, are not limited to the aforementioned mechanisms. In other words, another fluid pressure cylinder mechanisms such as air cylinders may be utilized as the moving and biasing means provided with the unbalance correction device according to the present invention. 
     As seen from the above, in the unbalance correction device  1  of the present embodiment, the pawl structures  10  press the flange portions  24   a  of the center housings  24  on the supporting surfaces  3   a  of the turbine housing portions  3 , by the locking portions  13  in the pawl portions  11 , thereby clamping and fixing the works  20  on the turbine housing portions  3 . Therefore, in the pawl structures  10 , the pawl portions  11  as the portions comprising the locking portions  13  become portions having intensities and rigidities enough for fixing the works  20  by the locking portions  13  (without damages or deformations due to the biasing by the cylinder mechanisms  30 . 
     In the present embodiment, three pawl structures  10  are used for fixing the work  20  on the turbine housing portion  3 . In other words, the unbalance correction device  1  of the present embodiment includes three pawl structures  10 . The flange portions  24   a  of the center housing  24  is pressed at three points, whereby the work  20  is fixed on the turbine housing portion  3  (see  FIG. 2 ). 
     In the unbalance correction device  1  of the present embodiment, three pawl structures  10  are provided as follows. 
     The annular flange portion  24   a  is provided at equal intervals in the circumferential direction thereof with three pawl structures  10 . Thus, as shown in  FIG. 2 , angular intervals between (the central positions of) the respective pawl structures  10  are 120° on the circumference centered at the position of the rotating shaft line, in the directional vision of the rotating shaft line of the work rotating portion (hereinafter, referred to as “in the directional vision of the rotating shaft line”). 
     As shown in  FIG. 2 , one pawl structure  10   a  out of three pawl structures  10  is disposed at the position where it is along the radial direction of the aforementioned work rotating portion in the circumferential direction of the flange portion  24   a  and the projecting direction of the locking portion  13  from the body portion  11   a  becomes the approximately vertical direction. Briefly, in the pawl structure  10   a , the locking portion  13  thereof is engaged on the upper end portion of the flange portion  24   a  with reference to the floor surface  7  (see  FIG. 1 ). Accordingly, the other two pawl structures  10   b ,  10   c  out of three pawl structures  10  provided at equal intervals in the aforementioned circumferential direction are located so that the pawl portions  11  are approximately symmetric in the circumferential direction of the flange portion  24   a  in the directional vision of the rotating shaft line as shown in  FIG. 2  (in the directional vision of the rotating shaft line when the floor surface  7  is on the down side). 
     In this respect, the cylinder mechanisms  30  are provided corresponding to the respective pawl structures  10   a ,  10   b  and  10   c . Three cylinder cases  31  corresponding to the respective pawl structures  10   a ,  10   b  and  10   c  are supported and fixed on the cylinder plate  9 . 
     Hereinafter, when three pawl structures  10  are distinctly described based on the provided positions, the pawl structure  10   a , which is disposed at the position where the projecting direction of the locking portion  13  from the body portion  11   a  becomes the approximately vertical direction as stated previously, is defined as “the first pawl structure  10   a ”. In the other two pawl structures  10   b ,  10   c  out of three pawl structures  10 , the pawl structure  10   b  at the position next to the first pawl structure  10   a  in the counterclockwise direction in the directional vision of the rotating shaft line as shown in  FIG. 2  is defined as “the second pawl structure  10   b ”, and the remaining pawl structure  10   c  (the pawl structure  10   c  on the right side in  FIG. 2 ) is defined as “the third pawl structure  10   c”.    
     By the same token, when three cylinder mechanisms  30  are distinctly described based on the pawl structure  10  supported in a moving and biasing manner, the cylinder mechanism  30  supporting the first pawl structure  10   a  in a moving and biasing manner is defined as “the first cylinder mechanism  30   a ”, and the cylinder mechanism  30  supporting the second pawl structure  10   b  in a moving and biasing manner is defined as “the second cylinder mechanism  30   b ”, as well as the cylinder mechanism  30  supporting the third pawl structure  10   c  in a moving and biasing manner is defined as “the third cylinder mechanism  30   c”.    
     In the unbalance correction device  1 , the respective cylinder mechanisms  30  are provided with the solenoid valves  35 . In other words, the unbalance correction device  1  includes three solenoid valves  35 . 
     The solenoid valves  35  are provided with pipings so as to supply the pressure oils to the first cylinder chambers  31   a  in the cylinder mechanisms  35 . In other words, the pressure oils supplied from the oil tanks to the first cylinder chambers  31   a  of the cylinder mechanisms  30  by the oil pumps are supplied via the solenoid valves  35 . Therefore, the distances of the pawl structures  10  to the work fixing directions and the biasing forces of the pawl structures  10  on the engaged condition to the work fixing directions are adjusted, by adjusting the switching or the opening degree of the solenoid valves  35 , i.e., by controlling the switching of the solenoid valves  35 . 
     Thus, the solenoid valves  35  are provided with the respective cylinder mechanisms  30  and function as clamp controlling means for controlling the distances of the pawl structures  10  to the moving directions by the cylinder mechanisms  30  and the biasing forces for biasing the pawl structures  10  to the work fixing directions. 
     Hereinafter, when three solenoid valves  35  are distinctly described based on the cylinder mechanisms  30  with which they are provided, the solenoid valve  35  provided with the first cylinder mechanism  30   a  is defined as “the first solenoid valve  35   a ”, and the solenoid valve  35  provided with the second cylinder mechanism  30   b  is defined as “the second solenoid valve  35   b ”, as well as the solenoid valve  35  provided with the third cylinder mechanism  30   c  is defined as “the third solenoid valve  35   c”.    
     The unbalance correction device  1  includes position sensors  37  in the respective pawl structures  10 . In other words, the unbalance correction device  1  of the present embodiment includes three position sensors  37 . 
     The position sensors  37  detect the positions of the pawl structures  10  on the engaged condition in the moving directions. The position sensors  37  are constituted as contact-free gap sensors (displacement sensors) that detect the positions (the displacements) of the pawl structures  10  to be measured in the moving directions, by detecting gaps between the pawl structures  10  in the moving directions. 
     In the embodiment, the position sensors  37  use apical surfaces  11   s  which are end faces on one ends of the pawl structures  10  in the moving directions and which are end faces of the pawl portions  11 , as detection target surfaces. In other words, the position sensors  37  detect the positions (the displacements) of the pawl structures  10  in the moving directions, by detecting gaps G 1  between the apical surfaces  11   s  of the pawl structures  10  (see  FIG. 1 ). As the position sensors  37  which are gap sensors, for example, eddy current type sensors, capacitance type sensors, laser sensors, ultrasonic sensors or the like can be utilized. 
     Thus, the position sensors  37  are provided with the respective pawl structures  10  and function as position detecting means that detect the positions of the pawl structures  10  on the engaged condition in the moving directions. 
     Hereinafter, when three position sensors  37  are distinctly described based on the pawl structures  10  with which the they are provided, the position sensor  37  provided with the first pawl structure  10   a  is defined as “the first position sensor  37   a ”, and the position sensor  37  provided with the second pawl structure  10   b  is defined as “the second position sensor  37   b ”, as well as the position sensor  37  provided with the third pawl structure  10   c  is defined as “the third position sensor  37   c”.    
     A controlling construction for the attitude control of the work  20 , in the unbalance correction device  1  of the present embodiment equipped with the above-mentioned construction, will be described with reference to  FIG. 3 . 
     As shown in  FIG. 3 , the unbalance correction device  1  of the present embodiment includes a control portion  39  for performing the attitude control of the work  20 . The control portion  39  controls the respective solenoid valves  35 , on the basis of detection signals output from the respective position sensors  37 . Accordingly, the position of the pawl structure  10  in the moving direction is controlled, and the attitude of the work  20  toward the turbine housing portion  3  is controlled. 
     The control portion  39  is connected to the respective solenoid valves  35  and the respective position sensors  37  via signal lines or the like. The control portion  39  issues signals so as to adjust the switching or the opening degrees of the solenoid valves  35 , i.e., to perform the switching operation of the solenoid valves  35  to the respective solenoid valves  35 . Accordingly, the control portion  39  performs the switching controls of the respective solenoid valves  35 . The control portion  39  receives signals on the positions of the respective pawl structures  10  on the engaged condition in the moving directions, detected by the respective position sensors  37 . In this way, the control portion  39  obtains information on the positions of the respective pawl structures  10  on the engaged condition in the moving directions. 
     The control portion  39  independently controls the respective solenoid valves  35 , based on the detection signals from the respective position sensors  37 . Specifically, the control portion  39  controls the first solenoid valve  35   a , based on the detection signal from the first position sensor  37   a , and the second solenoid valve  35   b , based on the detection signal from the second position sensor  37   b , as well as the third solenoid valve  35   c , based on the detection signal from the third position sensor  37   c . Accordingly, the positions of the respective pawl structures  10  on the engaged condition in the moving directions are independently controlled, whereby the attitude of the work  20  toward the turbine housing portion  3  is controlled. 
     The control portion  39  includes a storage portion which stores a program or the like, an expanding portion which expands the program or the like, a calculating portion which performs the predefined calculation according to the program or the like, a filing portion which files the calculated results or the like by calculation, a measuring portion which measures the position (the displacement) or the like of the pawl structures  10  on the engaged condition in the moving direction based on the detection signal output from the position sensor  37  and so on. The program or the like stored in the storage portion include the after-mentioned attitude control program. 
     As the control portion  39 , specifically, the construction that a CPU, a ROM, a RAM, a HDD or the like are connected together with a bus, or the configuration making up of one-chip LSI or the like are utilized. The control portion  39  of the present embodiment, which is exclusive goods, is also substitutable for the one which the aforementioned program or the like are stored in the commercially available personal computer, workstation and so forth. 
     The control portion  39  controls the respective solenoid valves  35  so that the shift lengths of the positions of the pawl structures  10  on the engaged condition in the moving directions detected by the position sensors  37  from the preset reference positions are smaller than the given acceptable amounts preliminary determined for the shift lengths. 
     The control portion  39  controls the solenoid valve  35  by carrying out the given calculation or the like in accordance with the attitude control program stored in the storage portion as described above. In other words, in the attitude control of the work  20 , the respective solenoid valves  35  are controlled by the control portion  39  based on the detection signals from the respective position sensors  37 , so that the attitude of the work  20  clamped on the turbine housing portion  3  is controlled. 
     In the attitude control of the work  20 , with reference to the positions of the pawl structures  10  on the engaged condition in the moving direction detected by the position sensors  37 , the preset reference position (hereinafter, simply referred to as “the reference position” on the pawl structure  10 ), is determined as follows. 
     In the present embodiment, as mentioned previously, the position sensors  37  detect the gaps G 1  between the apical surfaces  11   s  of the pawl structures  10  (see  FIG. 1 ), thereby detecting the positions (the displacements) of the pawl structures  10  in the moving directions. Consequently, the reference positions of the respective pawl structures  10  are determined by the largeness of the gap G 1 . Specifically, the given values on the largeness of the gaps G 1  between the apical surfaces  11   s  and the position sensors  37  are preliminary determined, in the respective pawl structures  10 , whereby the reference positions of the respective pawl structures  10  are established. 
     Hereinafter, the reference position of the first pawl structure  10   a  is defined as a reference value La on the gap G 1  between the first position sensor  37   a  and the apical surface  11   s  of the first pawl structure  10   a  (see  FIG. 3 ). More specifically, the condition that the gap G 1  between the first pawl structure  10   a  moving to the moving direction and the first position sensor  37   a  in place at the same time is the reference value La is the one that the first pawl structure  10   a  is at the reference position. Similarly, the reference position of the second pawl structure  10   b  is defined as the reference value Lb on the gap G 1  between the second position sensor  37   b  and the apical surface  11   s  of the second pawl structure  10   b , and the reference position of the third pawl structure  10   c  is defined as the reference value Lc on the gap G 1  between the third position sensor  37   c  and the apical surface  11   s  of the third pawl structure  10   c  (see  FIG. 3 ). 
     The reference positions of the respective pawl structures  10 , i.e., the respective values of the reference values, La, Lb and Lc are set up based on the prescribed reference attitude with reference to the attitude of the work  20  toward the turbine housing portion  3  (hereinafter, referred to as “the work attitude”), with the work  20  clamped on the turbine housing portion  3  (hereinafter, referred to as “the clamped condition”). In other words, the positions of the respective pawl structures  10  in the moving directions (the values of the gaps G 1 ) are set up as the reference positions of the respective pawl structures  10  (the reference values, La, Lb and Lc), when the there are the given reference attitudes in the work attitudes on the clamped condition and the work attitudes become the given reference attitudes. Accordingly, the respective pawl structures  10  are located at the reference positions, so that the work attitudes become the given reference attitudes. 
     For example, the reference positions of the respective pawl structures  10  are set up as follows. Specifically, as the present embodiment, in the construction that the work  20  is supported in the turbine housing portion  3  so that the direction of the rotating shaft line of the work rotating portion is the approximately horizontal direction, the reference positions of the respective pawl structures  10  are established, so that the positions of the respective pawl structures  10  in the moving direction (the direction of the rotating shaft line of the work rotating portion) are approximately the same among three pawl structures  10 . 
     In the attitude control of the works  20 , the solenoid valves  35  are controlled in such a way that the shift lengths of the pawl structures  10  from the reference positions are smaller than the given acceptable values that are preliminarily set up. The shift lengths (the differences) of the pawl structures  10  from the reference positions are the shift lengths of the pawl structures  10  on the engaged condition from the reference values, La, Lb and Lc from the moving directions. The predetermined acceptable values are preliminarily set up, with respect to the shift lengths of the pawl structures  10  from the reference positions in the moving directions (hereinafter, simply referred to as “the shift lengths in the pawl structures  10 ). 
     Specifically, when each of the shift lengths of the respective pawl structures  10  from the reference values La, Lb and Lc are defined as ΔLa, ΔLb and ΔLc, the respective solenoid valves  35  are controlled so that the values of the respective shift lengths ΔLa, ΔLb and ΔLc are smaller than the above-mentioned predetermined acceptable values, whereby the positions of the respective pawl structures  10  on the engaged condition in the moving directions are controlled. Briefly, in the attitude control of the work  20 , the positions of the respective pawl structures  10  on the engaged condition in the moving directions are controlled, via the respective solenoid valves  35 , so that the attitude of the work  20  clamped by three pawl structures  10  is controlled. 
     Consequently, when all of the predetermined acceptable values on the respective pawl structures  10  are ΔLx, each of the positions of the respective pawl structures  10  on the engaged condition in the moving directions, in the attitude control of the work  20 , are allowable in the range of the reference value La±ΔLx, the reference value Lb±ΔLx and the reference value Lc±ΔLx. The shift lengths of the pawl structures  10  are set up as much smaller values than the moving ranges of the pawl structures  10  in the moving directions (for example, about a few μm to a few dozens μm). 
     As seen from the above, the respective values used in the attitude control of the work  20 , i.e., the reference values La, Lb and Lc so as to define the reference positions of the respective pawl structures  10 , and the acceptable values on the shift lengths ΔLa, ΔLb and ΔLc from the respective reference values are preliminarily set up and memorized in the storage portion or the like in the control portion  39 . 
     The attitude control of the work  20  will be described with reference to a flow diagram of the attitude control of the work  20  as shown in  FIG. 4 . Incidentally, in the attitude control of the work  20  as described below, all of the acceptable values on the shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  are defined as 10 μm. 
     In the attitude control of the work  20 , first, the work  20  is set (Step S 100 ). More specifically, the flange portion  24   a  of the center housing  24  in the work  20  is fixed on the supporting recessed portion  3   b  forming the supporting surface  3   a  in the turbine housing portion  3 , whereby the work  20  is supported on the supporting surface  3   a . In this regard, at this stage, the pawl structures  10  are at the given waiting positions moving to the direction opposite to the work fixing direction, so as not to oppose the fixing of the work  20  on the turbine housing portion  3 . 
     When the work  20  is set up, the solenoid valves  35  provided in each of the cylinder mechanisms  30  are opened (Step S 110 ). Specifically, the pressure oils supplied from the oil tanks by the oil pumps are supplied to the first cylinder chambers  31   a  in the respective cylinder mechanisms  30  via the solenoid valves  35  on the opened conditions. Accordingly, the respective pawl structures  10  are pulled from the aforementioned given waiting positions, and are moved to the work fixing directions so as to be engaged on the set work  20 . 
     The respective pawl structures  10  on the engaged condition are biased to the work fixing directions due to the pressure oils supplied from the first cylinder chambers  31   a . Accordingly, the work  20  is on the clamped condition (Step S 120 ). When the work  20  is on the clamped condition, the respective solenoid valves  35  are occasionally closed for the meantime. The clamped condition of the work  20  in this case is referred to as “the tentative clamped condition”. 
     In the tentative clamped condition of the work  20 , sensor outputs from the respective position sensors  37  are performed, and the shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  are measured, based on the sensor outputs (Step S 130 ). In other words, after the work  20  is on the tentative clamped condition, the largeness of the gaps G 1  in the respective pawl structures  10  are measured based on the detection signals from the respective position sensors  37 . The shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  from the reference values La, Lb and Lc are measured, on the basis of the measurements of the gaps G 1  of the respective pawl structures  10 . 
     Subsequently, the shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  measured in the Step S 130  are evaluated where all of them are smaller 10 μm as the acceptable values (Step S 140 ). In other words, the shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  are evaluated whether they meet all the conditions of Δla&lt;10 μm, ΔLb&lt;10 μm, and ΔLc&lt;10 μm. 
     In the Step S 140 , when the shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  are evaluated that all of them are smaller than 10 μm as the acceptable values, the clamped condition of the work  20  is completed (Step S 160 ). Briefly, in this case, as the positions of the respective pawl structures  10  on the engaged condition in the moving direction are within error ranges allowed for the reference positions and the work attitude is the one within the error ranges allowed for the aforementioned given reference attitude, the clamped condition of the work  20  is completed. Accordingly, the attitude control of the work  20  is terminated. 
     Meanwhile, in the Step S 140 , when the shift lengths ΔLa, ΔLb and ΔLc of the respective pawl structures  10  are not evaluated that all of them are smaller than 10 μm as the acceptable values, the switching controls of the solenoid valves  35  are performed (Step S 150 ). Specifically, when the shift length ΔLa of the first pawl structure  10   a  is not evaluated that it is smaller than 10 μm, the position of the first pawl structure  10   a  in the moving direction is adjusted so that the shift length ΔLa becomes smaller, by controlling the switching of the first solenoid valve  35   a . Similarly, when the shift length ΔLb of the second pawl structure  10   b  is not evaluated that it is smaller than 10 μm, the position of the second pawl structure  10   b  in the moving direction is adjusted so that the shift length ΔLb becomes smaller, by controlling the switching of the second solenoid valve  35   b . When the shift length ΔLc of the third pawl structure  10   c  is not evaluated that it is smaller than 10 μm, the position of the third pawl structure  10   c  in the moving direction is adjusted so that the shift length ΔLc becomes smaller, by controlling the switching of the third solenoid valve  35   c.    
     In the Step S 150 , when the switching control in any of the solenoid valves  35  are performed and the position of the corresponding pawl structure  10  in the moving direction is adjusted, the other pawl structures  10  may be displaced. Briefly, the positioning of the pawl structures  10  by the switching controls of the solenoid valves  35  may mutually affect each other among three pawl structures  10 . For this reason, in the Step S 140 , the switching controls of the solenoid valves  35  in the Step S 150  and the evaluation in the Step S 140  are repeated, until the shift lengths ΔLa, ΔLb and ΔLc of three pawl structures  10  are evaluated that all of them are smaller than 10 μm. 
     Thus, the control portion  39  functions as the attitude control means so as to control the solenoid valves  35 , so that the shift lengths of the positions of the pawl structures  10  on the engaged condition in the moving direction from the reference positions, which is detected by the position sensors  37 , based on the detected values from the respective position sensors  37 , are smaller than the given acceptable values that is preliminarily determined for the shift lengths. Specifically, the control portion  39  functions as the attitude control means, by performing the prescribed calculations or the like in accordance with the attitude control program stored in the storage portion. 
     As seen from the above, the reduction of the productivity in the production line of the turbocharger  2  can be prevented, and the variations in the attitudes of the work  20  supported on the turbine housing portion  3  can be reduced, by performing the attitude control of the work  20 , thereby improving the accuracy of the unbalance correction. 
     Specifically, as the unbalance correction device  1  of the present embodiment, the clamp method by the pawl structures  10  is used for fixing the work  20  on the turbine housing portion  3 , whereby the reduction of the productivity in the production line of the turbocharger  2  can be prevented, compared with the case where the bolt fixation is used for fixing the work  20 . 
     Since the accident errors of the movements of three pawl structures  10  in the moving direction are sufficiently small values, in the attitude control of the work  20 , the variations in the work attitudes can be decreased, in the construction that the turbine housing portion  3  is used as a common jig for plurality of works  20 . Accordingly, the variations in the locking positions (the clamped positions) of the works  20  by the pawl structures  10  can be reduced, thereby lowering the variations in the largeness of the vibrations of the works  20  themselves, the vibrations transmitted to the acceleration pickup  4  via the turbine housing portion  3  or the like. Consequently, the accuracies in the unbalance corrections of the works  20  can be advanced. 
     Incidentally, the unbalance correction device  1  of the present embodiment includes the solenoid valves  35  provided with the pipings so as to supply the pressure oils into the first cylinder chambers  31   a , as clamping control means provided in the respective cylinder mechanisms  30 , but the above-mentioned clamping control means are not limited to them. The above-mentioned clamping control means may be the ones, which are provided in the respective cylinder mechanisms  30 , so as to control the distances moving the pawl structures  10  to the moving directions by the cylinder mechanisms  30  and the biasing forces so as to bias the pawl structures  10  to the work fixing directions. 
     As the above-mentioned clamping control means, for example, two solenoid valves provided on the pipings so as to supply the pressure oils to each of the first cylinder chambers  31   a  and the second cylinder chambers  31   b , may be used, in the cylinder mechanisms  30  constructed as the double-acting cylinders described above. Also, another valve systems or the like, performing the switching of supplying/disengaging, the adjusting of the flow volumes, in the pressure oils supplied to at least any of the or the first cylinder chambers  31   a  and the second cylinder chambers  31   b  or the like, may be used, as the above-mentioned clamping control means. 
     The unbalance correction device  1  of the present embodiment includes the position sensors  37  comprised as the contact-free gap sensors, as the position detecting means provided in the respective pawl structures  10 , but the above-mentioned position detecting means are not limited to them. The above-mentioned position detecting means may be the ones, which are provided in the respective pawl structures  10 , detecting the positions of the pawl structures  10  on the engaged condition in the moving directions. 
     As the above-mentioned position detecting means, for example, another straight line position sensors, such as proximity switch or contact gap sensors may be used, as long as they have the enough accuracies to detect the shift lengths of the pawl structures  10  in the tentative clamped condition of the work  20  (for example, the accuracies in the order of a few μm to a few dozens μm). 
     In the meantime, in the unbalance correction device  1  of the present embodiment, the work  20  are clamped and fixed on the turbine housing portion  3  by three pawl structures  10 . 
     As described above, in the unbalance correction device  1  comprising the construction that the clamp method by the pawl structures  10  are used for fixing the work  20  on the turbine housing portion  3 , the pawl structures  10  as the members clamping the work  20  are vibrated to the turbine housing portion  3  (at natural frequency different from the device body including and integral with the turbine housing portion  3 ), with rotation of the work rotating portion. 
     More specifically, in the unbalance correction device  1  including the construction that the clamp method is used as mentioned previously, the pawl structures  10  are vibrated to the device body that the respective members including the trestle  5  and the turbine housing portion  3  provided thereon are integrally comprised, with rotation of the work rotating portion. Basically, the device body and the pawl structures  10  have different natural frequencies, in the unbalance correction device  1 . 
     In the pawl structures  10 , the pawl portions  11  need to be portions that have sufficient intensities and rigidities for fixing the work  20 , so as to fix the work  20  by the locking portions  13  as mentioned before. 
     Thus, as shown in the pattern diagram of  FIG. 5 , the pawl structure  10  has the pawl portion  11  as a heavy load on the other end side (the apical end) of the thin (small-diameter) rod portion  12  provided in the approximately horizontal direction and supported on one end thereof by the cylinder mechanism  30 . Due to this construction, the pawl portion  11  is vibrated via the rod portion  12 , with rotation of the work rotating portion, thereby causing the relative vibration of the pawl structure  10 , to the cylinder mechanism  30  included in the above-mentioned device body in the unbalance correction device  1  (see an arrow A 1 ). Accordingly, the pawl structure  10  vibrates at the natural frequency different from the device body. 
     The vibration of the pawl structure  10  caused due to the rotation of the work rotating portion in the unbalance correction device  1  will be described with reference to  FIGS. 6 and 7 . 
     In the unbalance correction device  1  of the present embodiment, the pawl structure  10  can be said to be floating by the fluid (the air in the present embodiment) in the cylinder case  31  of the cylinder mechanism  30 . In other words, the pawl structure  10  can be said to be floating relative to the device body of the unbalance correction device  1 . 
     In this regard, the unbalance correction device  1  includes a mass as the device body which is one large mass (hereinafter, referred to as “the body mass”), and a mass as the pawl structure  10  which is comprised of three small masses (hereinafter, referred to as “the pawl mass”, as the mass (the mass body). 
     Specifically, in the unbalance correction device  1  of the present embodiment, as shown in  FIG. 7  ( a ), the body mass includes a trestle  5 , a supporting wall  6 , a turbine housing portion  3 , a work  20 , a cylinder plate  9  and a cylinder case  31 , and is formed as one mass that they are integrally constructed by the bolt fixation or the like. The pawl mass, as shown in  FIG. 7(   b ), has a pawl portion  11  and a rod portion  12 , and becomes the mass as one pawl structure  10  that they are integrally constructed. Therefore, the unbalance correction device  1  has three pawl masses comprising of the pawl mass as the first pawl structure  10   a  (the first pawl mass), the pawl mass as the second pawl structure  10   b  (the second pawl mass) and the pawl mass as the third pawl structure  10   c  (the third pawl mass). 
     Thus, by using the concept that the unbalance correction device  1  includes one body mass and three pawl masses, in the unbalance correction device  1 , the respective pawl structures  10  can be replaced by the single-degree-of-freedom vibration model in the device body. 
     Specifically, as shown in  FIG. 6 , the unbalance correction device  1  which is modeled as mentioned above has mass m 1  of the first pawl mass  41 , mass m 2  of the second pawl mass  42  and mass m 3  of the third pawl mass  43 , with reference to mass m 0  of the body mass  40 . The first pawl mass  41  is connected via a spring constant k 1  of spring  41   a  and a damping constant c 1  of damper  41   b  to the body mass  40 . Similarly, the second pawl mass  42  is connected via a spring constant k 2  of spring  42   a  and a damping constant c 2  of damper  42   b  to the body mass  40 , and The third pawl mass  43  is connected via a spring constant k 3  of spring  43   a  and a damping constant c 3  of damper  43   b  to the body mass  40 . Incidentally, the body mass  40  is connected to the floor surface  7  (see  FIG. 1 ) at the given spring constant and damping constant. 
     In this respect, in the first pawl mass  41 , the spring constant k 1  shows a total rigidity in the system of the mass m 1 . Similarly, in the second pawl mass  42 , the spring constant k 2  shows a total rigidity in the system of the mass m 2 , and in the third pawl mass  43 , the spring constant k 3  shows a total rigidity in the system of the mass m 3 . Incidentally, the total rigidity in the respective pawl masses  41  to  43  include the rigidity against the reaction force acting on the pressing surface  13   a  (see  FIG. 1 ), during the clamp by the pawl structures  10 , with the work  20  fixed on the turbine housing portion  3  (hereinafter, referred to as “the clamp rigidity”). The clamp rigidity varies depending on the largeness in the force that the pawl structure  10  is biased by the cylinder mechanism  30  (the pressing force from the locking portion  13 ). 
     In the first pawl mass  41 , the damping constant c 1  shows a total damping in the system of the mass m 1 . Similarly, in the second pawl mass  42 , the damping constant c 2  shows a total damping in the system of the mass m 2 , and in the third pawl mass  43 , the damping constant c 3  shows a total damping in the system of the mass m 3 . 
     In this regard, the total mass of the respective pawl structures  10 , the total rigidity and the total mass will be described. 
     As shown in  FIG. 8 , the total mass of the pawl structure  10  means a sum of the mass of the pawl portion  11  in the pawl structure  10  and that of the rod portion  12 . Briefly, if the total mass of the pawl structure  10  is mall, the mass of the pawl portion  11 , m T  the mass of the rod portion  12 , m R , m all =m T +m R . 
     The total rigidity (the spring constant) of the pawl structure  10  includes the rigidity of the pawl portion  11 , the rigidity of the rod portion  12  in the pawl structure  10  and the clamp rigidity (see an arrow D 1 ). When the total rigidity of the pawl structure  10  is k all , the rigidity of the pawl portion  11 , k T , the rigidity of the rod portion  12 , k R , the clamp rigidity, k F , the following formula (1) is established:
 
1 /k   all =(1 /k   T )+(1 /k   R )+(1 /k   F )  (1)
 
Therefore,
 
 k   all   =k   T   k   R   k   F /( k   R   k   F   +k   F   k   T   +k   T   k   R )
 
     The total damping of the pawl structure  10  means the damping coefficient of the pawl structure  10  supported in the moving and biasing manner, by the cylinder mechanism  30  constituted as the hydraulic cylinder. Specifically, the pawl structure  10  supported via the oils in the cylinder case  31  receives the viscous resistance (the viscous damping) caused by the relative movement to the oils when it is vibrated. The viscous resistance converts the kinetic energy of the pawl structure  10  into the thermal energy, so as to exert the pawl structure  10  on the damping force (the viscous damping force). The damping force acting on the pawl structure  10  is in proportion to the vibration velocity of the pawl structure  10 . The proportional constant to the velocity of the damping force is the damping coefficient (the viscous coefficient) of the pawl structure  10  having the pawl portion  11  and the rod portion  12  in an integrated manner as mentioned before, thereby forming the total damping of the pawl structure  10 . 
     In the aforementioned vibration model of the pawl structure  10  (see  FIG. 6 ), the mass m 1  shows the total mass of the first pawl structure  10   a , and the mass m 2  shows the total mass of the second pawl structure  10   b , as well as the mass m 3  the total mass of the third pawl structure  10   c , respectively. The spring constant k 1  shows the total rigidity of the first pawl structure  10   a , and the spring constant k 2  shows the total rigidity of the second pawl structure  10   b , as well as the spring constant k 3  the total rigidity of the third pawl structure  10   c , respectively. The damping coefficient c 1  shows the total damping of the first pawl structure  10   a , and the damping coefficient c 2  shows the total damping of the second pawl structure  10   b , as well as the damping coefficient c 3 , the total damping of the third pawl structure  10   c , respectively. 
     As seen from the above, the vibrations of the respective pawl structures  10  in the moving directions with rotation of the work rotating portion can be considered as single-degree-of-freedom system forced vibration having the damping (the viscous damping) for the device body. In other words, the periodical external force as the forced vibration force acts on the respective pawl structures  10  represented by the respective pawl masses  41  to  43  (the pawl system), with rotation of the work rotating portion, whereby the respective pawl structures  10  vibrate to the device body represented as the body mass  40  (the body system) with damping in the moving directions. 
     Therefore, when the coordinate (the displacement to the reference position) in the moving direction of the pawl structure  10  is X, and the periodical external force as the forced vibration force acting on the pawl structure  10  with rotation of the work rotating portion is F sin ωt (ω: the angular frequency, t: time), the following formula (2) is established as a common motion equation showing single-degree-of-freedom system vibration with damping. 
     
       
         
           
             
               
                 
                   [ 
                   
                     Formula 
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                     1 
                   
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                         m 
                         ⁢ 
                         
                           x 
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                       + 
                       
                         c 
                         ⁢ 
                         
                           x 
                           . 
                         
                       
                       + 
                       kx 
                     
                     = 
                     
                       F 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       sin 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       ω 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       t 
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       x 
                       . 
                     
                     = 
                     
                       
                         ⅆ 
                         x 
                       
                       
                         ⅆ 
                         t 
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       x 
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                     = 
                     
                       
                         
                           ⅆ 
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                         x 
                       
                       
                         
                           ⅆ 
                           t 
                         
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     Incidentally, in the formula (2), the m corresponds to the total mass of the pawl structure  10 , and the c corresponds to the total damping (the damping coefficient) of the pawl structure  10 , as well as the k corresponds to the total rigidity (the spring constant) of the pawl structure  10 . 
     In the formula (2), when the total mass, the total damping and the total rigidity of the pawl structure  10  are preliminarily showed by the measurement or the line, the excitation force (the largeness/direction) acting on the pawl structure  10  with rotation of the work rotating portion is derived due to the displacement x of the pawl structure  10  from the reference position. 
     Specifically, when excitation force acting on the first pawl structure  10   a  is Fa, and the excitation force acting on the second pawl structure  10   b  is Fb, as well as the excitation force acting on the third pawl structure  10   c  is Fc, with reference to the excitation forces acting on the respective pawl structures  10  with rotation of the work rotating portion, the following formulas (3) to (5) are established, based on the above-mentioned formula (2).
 
[formula 2]
 
 m 1 {umlaut over (x)}+c 1 {dot over (x)}+k 1 x=F   a   (3)
 
[formula 3]
 
 m 2 {umlaut over (x)}+c 2 {dot over (x)}+k 2 x=F   b   (4)
 
[formula 4]
 
 m 3 {umlaut over (x)}+c 3 {dot over (x)}+k 3 x=F   c   (5)
 
     Thus, the excitation forces acting on the respective pawl structures  10  are derived from the aforementioned formulas (3) to (5), with respect to the vibrations of the respective pawl structures  10  in the moving directions on the device body with rotation of the work rotating portion. 
     In this regard, in the unbalance correction device  1 , the forces negating the excitation forces acting on the respective pawl structures  10  with rotation of the work rotating portion are exerted on the respective pawl structures  10  as the damping forces, for the unbalance correction, whereby the active damping controls restraining the natural vibrations (behavior) of the respective pawl structures  10  to the device body are performed. The unbalance correction device  1  of the present embodiment includes the following construction, so as to perform the damping controls for the respective pawl structures  10 . Incidentally, with regard to the following description, in the damping controls of the respective pawl structures  10 , the vibration direction of the pawl structure  10  as the damping object is defined as the moving direction of the pawl structure  10  (the lateral direction in  FIG. 1 ), and the direction is defined as the direction of the X-axis. Briefly, in the following description, the “vibration” on the pawl structure  10  means the one in the moving direction of the pawl structure  10  (in the direction of the X axis). 
     As shown in  FIG. 9 , the unbalance correction device  1  is provided in the respective pawl structures  10  with displacement sensors  50 . In other words, the unbalance correction device  1  of the present embodiment includes three displacement sensors  50 . Incidentally, in the  FIG. 9 , for convenience of explanation, the position of the third cylinder mechanism  30   c  in the unbalance correction device  1  is represented by displacing from the original position as shown in  FIG. 2 . 
     The displacement sensor  50  detects the displacement (the displacement magnitude and the displacement direction) of the pawl structure  10  with the work  20  clamped on the turbine housing portion  3 , due to the vibration with rotation of the work rotating portion. The displacement sensor  50  is comprised as the contact-free gap sensor, which detects the displacement due to the vibration of the pawl structure  10  as the object to be measured, by detecting the gap between the pawl structures  10  thereof in the moving direction. 
     In the present embodiment, the displacement sensor  50  detects the apical surfaces  11   s , as the end surface of the pawl portion  11 , which is an end face on one end of the pawl structure  10  in the moving direction. In other words, the displacement sensor  50  detects the displacement due to the vibration of the pawl structure  10 , by detecting the gap G 2  between the apical surfaces  11   s  of the pawl structure  10  (see  FIG. 9 ). For example, a eddy current sensor, capacitance sensor, a laser sensor or an ultrasonic sensor or the like can be utilized, as the displacement sensor  50 . 
     The displacement sensor  50  detects the displacement due to the relative vibration to the device body, regarding the vibration of the pawl structure  10 . Specifically, the displacement sensor  50  is provided so that the sensor  50  itself vibrates integrally with device body, or the vibration of the device body is added to the detection value by the displacement sensor  50  or the like, whereby the sensor  50  detects the displacement due to the relative vibration to the device body of the pawl structure  10 . 
     In the present embodiment, the displacement sensor  50  has a reference position portion  51  in the turbine housing portion  3 . Briefly, in the present embodiment, the displacement sensor  50  detects the displacement due to the vibration of the pawl structure  10 , using the turbine housing portion  3  having the reference position portion  51  as a reference position. In other words, the displacement sensor  50  detects the displacement due to the relative vibration of the pawl structure  10  to the turbine housing portion  3 . The reference positions for the displacement sensor  50  are not especially limited, as long as they are any positions in the device body including the turbine housing portion  3  and comprised integral with it. 
     The default position (the reference position as X=0) of the pawl structure  10  for detecting the displacement due to the vibration of the pawl structure  10  by the displacement sensor  50  becomes the position of the pawl structure  10 , at the time when the clamping of the work  20  on the turbine housing portion  3  has been finished using the pawl structure  10 . Therefore, for example, as mentioned above, when the attitude control of the work  20  is performed, the positions of the respective pawl structures  10  at the time when the clamping for the work  20  has been finished in the attitude control of the work  20  become the default positions of the pawl structures  10  for the respective displacement sensor  50 . 
     As just described, the displacement sensors  50  are disposed in the respective pawl structures  10  and function as the displacement sensing means which detect the displacements due to the vibrations of the pawl structures  10 , with the work  20  clamped on the turbine housing portion  3 , to the device body with rotation of the work rotating portion. 
     Hereinafter, when three displacement sensors  50  are distinctly described according to the pawl structures  10  provided thereof, the displacement sensor  50  disposed in the first pawl structure  10   a  is defined as “the first displacement sensor  50   a ”, the displacement sensor  50  disposed in the second pawl structure  10   b  is defined as “the second displacement sensor  50   b ”, as well as the displacement sensor  50  disposed in the third pawl structure  10   c  is defined as “the third displacement sensor  50   c ”. The vibratory displacement of the first pawl structure  10   a  detected by the first displacement sensor  50   a  is defined as Xa, and the vibratory displacement of the second pawl structure  10   b  detected by the second displacement sensor  50   b  is defined as Xb, as well as the vibratory displacement of the third pawl structure  10   c  detected by the third displacement sensor  50   c  is defined as Xb is defined as Xc. 
     As shown in  FIG. 9 , the unbalance correction device  1  is provided in the respective cylinder mechanisms  30  with solenoid changeover valves  52 . In other words, the unbalance correction device  1  of the present embodiment includes three solenoid changeover valves  52 . 
     The solenoid changeover valves  52  change over the directions to which the pawl structures  10  are moved (the directions to which the pawl structures  10  are biased) in the moving directions thereof. The concrete procedure goes as follows. 
     More specifically, as mentioned above, the cylinder mechanism  30  is comprised as the double-acting cylinder having the first cylinder chamber  31   a  and the second cylinder chamber  31   b  in the cylinder case  31 . As shown in  FIG. 9 , the first cylinder chamber  31   a  is continuously connected at the doorway of the oil thereof to the first oil passage  53   a . The supply of the pressure oil to the first cylinder chamber  31   a  and the discharge (the retracting) of the oil from the first cylinder chamber  31   a  are performed, through the first oil passage  53   a . Similarly, the second cylinder chamber  31   b  is continuously connected at the doorway of the oil thereof to the second oil passage  53   b . The supply of the pressure oil to the second cylinder chamber  31   b  and the discharge (the retracting) of the oil from the second cylinder chamber  31   b  are performed, through the second oil passage  53   b.    
     As shown in  FIG. 9 , each of the first oil passage  53   a  and the second oil passage  53   b  provided at the respective cylinder mechanisms  30  are connected to a supplying oil passage  54   a  and a detracting oil passage  54   b , via the solenoid changeover valves  52 . These supplying oil passage  54   a  and a detracting oil passage  54   b  are connected to an oil tank  56  via an oil pump  55 . Briefly, the oils stored in the oil tank  56  are supplied from the supplying oil passage  54   a  via the solenoid changeover valves  52  to each of the cylinder mechanisms  30 , using the oil pump  55 . The oils retracted from each of the cylinder mechanisms  30  are retracted from the retracting oil passage  54   b  via the solenoid changeover valves  52  to the oil tank  56 . 
     In this regard, when the pawl structures  10  are moved and biased in the directions to which they are pulled (the work fixing directions), the pressure oils via the solenoid changeover valves  52  are supplied from the first oil passages  53   a  into the first cylinder chamber  31   a  and the oils in the second cylinder chambers  31   b  is retracted from the second oil passages  53   b  via the solenoid changeover valves  52 . On the other hand, when pawl structures  10  are moved and biased in the directions to which they are pushed out (the directions opposite to the work fixing directions), the pressure oils via the solenoid changeover valves  52  are supplied from the second oil passages  53   b  into the second cylinder chambers  31   b  and the oils in the first cylinder chambers  31   a  are retracted from the first oil passage  53   a  via the solenoid changeover valves  52 . 
     In the above-mentioned constructions supplying/discharging the oils for the respective cylinder mechanisms  30 , the solenoid changeover valves  52  change over the supplies of the pressure oils to the first cylinder chambers  31   a  (the retracting of the oils from the second cylinder chambers  31   b ) and the supplies of the pressure oils to the second cylinder chambers  31   b  (the retracting of the oils from the first cylinder chambers  31   a ). 
     The solenoid changeover valve  52  is constituted as so-called solenoid operating four ports changeover valve. Specifically, in the solenoid changeover valve  52 , the solenoid (the electromagnet) is operated via the relay, based on the given control signal (the electric signal), and the spool is moved by the force thereof, thereby changing over the flow passage in the hydraulic circuit. The solenoid changeover valve  52  is comprised as so-called three-position valve. Briefly, in the solenoid changeover valve  52 , the spool is changed over at three points and the flow passages corresponding to the positions of the respective spools are formed. 
     The changeover of the flow passage by the solenoid changeover valve  52  in the unbalance correction device  1  of the present embodiment will be described with reference to  FIG. 11 . 
     In the solenoid changeover valve  52  comprised as the aforementioned three position valve, three conditions are changed over, the conditions comprising of the continuous connection condition (the first condition) of the first oil passage  53   a  and the supplying oil passage  54   a  as well as the second oil passage  53   b  and the retracting oil passage  54   b , and the continuous connection condition (the second condition) of the first oil passage  53   a  and the retracting oil passage  54   b , as well as the second oil passage  53   b  and the supplying oil passage  54   a , and the blocking condition (the unconnected condition) of the flow passage (the third condition). 
     Specifically, the solenoid changeover valve  52  has four ports to which each of the first oil passage  53   a , the second oil passage  53   b , the supplying oil passage  54   a  and the retracting oil passage  54   b  are continuously connected. In this regard, as shown in  FIG. 11 , with respect to four ports in the solenoid changeover valve  52 , the port connected to the first oil passage  53   a  is defined as a port Pa 1 , and the port connected to the second oil passage  53   b  is defined as a port Pb 1 , and the port connected to the supplying oil passage  54   a , a port Pa 2 , as well as the port connected to the retracting oil passage  54   b , a port Pb 2 . 
       FIG. 11  ( a ) shows the above-mentioned first condition in the solenoid changeover valve  52 . In the solenoid changeover valve  52  on this condition, the respective ports are connected so that the port Pa 2  is connected to the port Pa 1  and the port Pb 1  is connected to the port Pb 2 . Specifically, the supplying oil passage  54   a  and the first oil passage  53   a  are continuously connected, whereby the pressure oil is supplied into the first cylinder chamber  31   a , and the second oil passage  53   b  and the retracting oil passage  54   b  are continuously connected, whereby the oil in the second cylinder chamber  31   b  is retracted. Accordingly, the pawl structure  10  is moved and biased in the direction to which it is pulled (the work fixing direction) (see an arrow B 1 ). 
       FIG. 11  ( b ) shows the aforementioned second condition in the solenoid change over valve  52 . In the solenoid changeover valve  52  on this condition, the port Pa 2  is connected to the port Pb 1 , and the port Pa 1  is connected to the port Pb 2 . Briefly, the supplying oil passage  54   a  and the second oil passage  53   b  are continuously connected, whereby the pressure oil is supplied in the second cylinder chamber  31   b , as well as the first oil passage  53   a  and the retracting oil passage  54   b  are continuously connected, whereby the oil in the first cylinder chamber  31   a  is retracted. Accordingly, the pawl structure  10  is moved and biased in the pushed direction (the direction opposite to the work fixing direction) (see an arrow B 2 ). 
       FIG. 11  ( c ) shows the aforementioned third condition in the solenoid changeover valve  52 . In the solenoid changeover valve  52  on this condition, the respective ports are covered and blocked by the spools. Briefly, all of the first oil passage  53   a , the second oil passage  53   b , the supplying oil passage  54   a  and the retracting oil passage  54   b  are blocked in the respective ports, and the supply/discharge of the oils are blocked in the cylinder mechanism  30 . Therefore, on this condition, the hydraulic pressures in the first cylinder chamber  31   a  and the second cylinder chamber  31   b  of the cylinder mechanism  30  are retained. 
     Since the switching of the flow passages by the solenoid changeover valve  52  are performed by switching the positions of the spools as mentioned above, hereinafter, in the switching of the flow passages by the solenoid changeover valve  52 , the above-mentioned first condition is defined as the position P 1  (see  FIG. 11  ( a )), and the above-mentioned second condition is defined as the position P 2  (see  FIG. 11  ( b )), as well as the above-described third condition, the position PN (see  FIG. 11  ( c )). Briefly, the solenoid changeover valve  52  is on any conditions of the positions P 1 , P 2  and PN, so that the switching of the flow passages is performed using the solenoid changeover valve  52 . Accordingly, the moving and biasing direction is switched in the moving direction of the pawl structure  10 . 
     As seen from the above, the solenoid changeover valves  52  are provided in the respective cylinder mechanisms  30  and function as the direction switching means for switching the moving and biasing directions in the moving directions of the pawl structures  10  by the cylinder mechanisms  30 . 
     Hereinafter, when three solenoid changeover valves  52  are distinctly described according to the cylinder mechanisms  30  provided, the solenoid changeover valve  52  disposed at the first cylinder mechanism  30   a  is defined as “the first solenoid changeover valve  52   a ”, and the solenoid changeover valve  52  disposed at the second cylinder mechanism  30   b  is defined as “the second solenoid changeover valve  52   b , as well as the solenoid changeover valve  52  disposed at the third cylinder mechanism  30   c , “the third solenoid changeover valve  52   c”.    
     In the unbalance correction device  1 , supplying flow control valves  61  and retracting flow control valves  62  are provided in the respective cylinder mechanisms  30 . In other words, the unbalance correction device  1  of the present embodiment includes three supplying flow control valves  61  and three retracting flow control valves  62 . 
     The supplying flow control valves  61  control the flow rates of the pressure oils supplied from the oil tans  56  to the cylinder mechanisms  30  by the oil pumps  55 . Specifically, as shown in  FIG. 9 , the supplying flow control valves  61  are provided at the supplying oil passages  54   a  and control the flow rates of the pressure oils supplied to the cylinder mechanisms  30  between the oil pumps  55  and the solenoid changeover valves  52 . 
     The retracting flow control valves  62  control the flow rates of the oils retracted from the cylinder mechanisms  30  to the oil tanks  56 . Specifically, as shown in  FIG. 9 , the retracting flow control valves  62  are provided at the retracting oil passages  54   b  and control the flow rates of the oils retracted from the cylinder mechanisms  30  between the solenoid changeover valves  52  and the oil pumps  55 . 
     Each of the supplying flow control valves  61  and the retracting flow control valves  62  are comprised as one-way restrictors having check valves. That is, in the supplying flow control valves  61  the flows in the supplying direction to the cylinder mechanisms  30  become the control flows, and the flows in the opposite directions thereof become the free flows. Meanwhile, in the retracting flow control valves  62 , the flows in the retracting directions from the cylinder mechanisms  30  become the control flows, and the flows in the opposite directions thereof become the free flows. 
     As mentioned above, the flow rates of the oils supplied to and discharged from the cylinder mechanisms  30  via the solenoid changeover valves  52  are controlled, by the supplying flow control valves  61  and the retracting flow control valves  62 , thereby controlling the largeness of the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30 . More specifically, by controlling the flow rates of the oils using the supplying flow control valves  61  and the retracting flow control valves  62 , when the solenoid changeover valves  52  are on the positions P 1 , the largeness of the biasing forces acting on the directions pulling the pawl structures  10  by the cylinder mechanisms  30  is controlled, and when the solenoid changeover valves  52  are on the positions P 2 , the largeness of the biasing forces acting on the directions pushing the pawl structures  10  by the cylinder mechanisms  30  is controlled. 
     Thus, the supplying flow control valves  61  and the retracting flow control valves  62  are provided at the respective cylinder mechanisms  30 , and function as the biasing force control means for controlling the biasing forces biasing the pawl structures  10  by the cylinder mechanisms  30 , in the moving and biasing directions of the pawl structures  10  defined by the solenoid changeover valves  52 . 
     Hereinafter, when three supplying flow control valves  61  are distinctly described according to the cylinder mechanisms  30  provided, the supplying flow control valve  61  disposed at the first cylinder mechanism  30   a  is defined as “the first supplying flow control valve  61   a ”, and the supplying flow control valve  61  disposed at the second cylinder mechanism  30   b  is defined as “the second supplying flow control valve  61   b ”, as well as the supplying flow control valve  61  disposed at the third cylinder mechanism  30   c , “the third supplying flow control valve  61   c ”. Similarly, the retracting flow control valve  62  disposed at the first cylinder mechanism  30   a  is defined as “the first retracting flow control valve  62   a ”, and the retracting flow control valve  62  disposed at the second cylinder mechanism  30   b  is defined as “the second retracting flow control valve  62   b ”, as well as the retracting flow control valve  62  disposed at the third cylinder mechanism  30   c , “the third retracting flow control valve  62   c”.    
     In the unbalance correction device  1 , the work  20  on the clamped condition is provided with a rotation sensor  57  for detecting the rotation of the work rotating portion thereof. As the rotation sensor  57 , for example, contact-free rotational displacement (rotational angle) sensor such as optical sensor or magnetic sensor are utilized. 
     The control construction of the damping control for the pawl structure  10  in the unbalance correction device  1  of the present embodiment equipped with the above-described constitutions will be described with reference to  FIG. 10 . 
     As shown in  FIG. 10 , the unbalance correction device  1  of the present embodiment includes a control system  70  so as to perform the damping control for the pawl structure  10 . The control system  70  controls the respective solenoid changeover valves  52 , the respective supplying flow control valves  61  and the retracting flow control valves  62 , based on the detection signals output from the respective displacement sensors  50 . Accordingly, the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30  are controlled, thereby damping the vibrations of the pawl structures  10  to the device body (the turbine housing portion  3 ). 
     The control system  70  is connected to the respective displacement sensors  50 , the respective solenoid changeover valves  52 , the respective supplying flow control valves  61  and the respective retracting flow control valves  62 . The control system  70  receives the signals on the displacements due to the vibrations of the pawl structures  10  clamping the work  20 , detected by the respective displacement sensors  50 . Accordingly, the control system  70  obtains the information on the displacements due to the vibrations of the pawl structures  10  clamping the work  20 . The control system  70  issues the control signals to the respective solenoid changeover valves  52 , the respective supplying flow control valves  61  and the retracting flow control valves  62 . Briefly, the control system  70  issues the signals so as to switch the flow passages for the respective solenoid changeover valves  52  (the positions of the solenoid changeover valves  52 ). Accordingly, the control system  70  performs the switching controls of the respective solenoid changeover valves  52 . The control system  70  sends the signals for controlling the flow rates (the valve opening degrees) to the respective supplying flow control valves  61  and the respective retracting flow control valves  62 . Accordingly, the control system  70  performs the conditioned controls for the respective supplying flow control valves  61  and the respective retracting flow control valves  62 . 
     The control system  70  independently controls the respective solenoid changeover valves  52 , the respective supplying flow control valves  61  and the respective retracting flow control valves  62 , based on the detection signals from the respective displacement sensors  50 . More specifically, the control system  70  controls the first solenoid changeover valve  52   a , the first supplying flow control valve  61   a  and the first retracting flow control valve  62   a , based on the detection signal from the first displacement sensor  50   a , and controls the second solenoid changeover valve  52   b , the second supplying flow control valve  61   b  and the second retracting flow control valve  62   b , based on the detection signal from the second displacement sensor  50   b , as well as controls the third solenoid changeover valve  52   c , the third supplying flow control valve  61   c  and the third retracting flow control valve  62   c , based on the detection signal from the third displacement sensor  50   c . Consequently, the cylinder mechanisms  30  acting the biasing forces on the pawl structures  10  clamping the work  20  are independently controlled, thereby damping the vibrations of the respective pawl structures  10  to the device body (the turbine housing portion  3 ). 
     The control system  70  is connected to the rotation sensor  57 . The control system  70  receives the signal on the rotational displacement (the rotational angle) of the work rotating portion in the work  20  on the clamped condition, detected by the rotation sensor  57 . Accordingly, the control system  70  acquires the information on the rotational displacement (the rotational angle) of the work rotating portion in the work  20  on the clamped condition. 
     The control system  70  has a storage portion which stores a program or the like, an expanding portion which expands the program or the like, a calculating portion which performs the predefined calculation according to the program or the like, a filing portion which files the calculated results or the like by calculating portion, a measuring portion which measures the displacements due to the vibrations of the pawl structures  10  clamping the work  20  or the like, based on the detection signals output from the displacement sensors  50  and so on. The program or the like stored in the aforementioned storage portion include an after-mentioned excitation force calculation program, a damping force calculation program and a damping control program. 
     As the control system  70 , specifically, the construction that a CPU, a ROM, a RAM, a HDD or the like are connected together with a bus, or the configuration making up of one-chip LSI or the like are utilized. The control system  70  of the present embodiment, which is exclusive goods, is also substitutable for the one which the aforementioned program or the like are stored in the commercially available personal computer, workstation and so forth. 
     The control system  70  has an excitation force calculating portion  71 , a damping force calculating portion  72  and a damping control portion  73 . 
     The excitation force calculating portion  71  calculates the excitation forces acting on the pawl structures  10  in the moving directions with rotation of the work rotating portion, based on the displacements of the pawl structures  10  detected by the displacement sensors  50 , as well as the total mass of the pawl structures  10 , the total damping of the pawl structures  10  in the moving directions and the total rigidity of the pawl structures  10  in the moving directions. 
     The control system  70  exerts the predetermined calculation or the like according to the excitation force calculation program stored in the storage portion thereof, whereby the calculation of the excitation force by the excitation force calculating portion  71  is performed as mentioned above. Briefly, in the damping control of the pawl structure  10 , the excitation forces acting with rotation of the work rotating portion, on the respective pawl structures  10  clamping the work  20  are calculated by the excitation force calculating portion  71 . 
     When the excitation forces acting on the pawl structures  10  by the excitation force calculating portion  71  are calculated, the respective values of the displacements due to the vibrations, the total mass, the total damping and the total rigidity of the pawl structures  10  are utilized. 
     In this regard, the displacements due to the vibrations of the pawl structures  10  are detected using the displacement sensors  50 . Basically, the displacements due to the vibrations of the pawl structures  10  are the ones (the x values) of the pawl structures  10  in the vibration directions (the X-axis direction, see  FIG. 9 ), when the positions of the pawl structures  10  at the time of finishing the clamping of the work  20  are set up as the default positions (the reference positions as x=0), detected by the displacement sensors  50  as described above. In other words, the displacements due to the vibrations of the pawl structures  10  detected by the displacement sensors  50  become the ones when the pawl structures  10  receive the excitation forces. 
     The total mass of the pawl structures  10  are sum (m all ) of the masses of the pawl portions  11  and those of the rod portions  12  in the pawl structures  10 . The total damping of the pawl structures  10  are damping coefficients for the vibrations of the pawl structures  10  supported on the cylinder mechanisms  30  comprised as the hydraulic cylinders in a moving and biasing manner. The total rigidity of the pawl structures  10  are the spring constants (k all ) on the vibrations derived from the above-mentioned formula (1), based on the rigidities of the pawl portions  11 , those of the rod portions  12  and the clamp rigidities in the pawl structures  10 . 
     The excitation force calculating portion  71  calculates the excitation forces acting on the respective pawl structures  10  clamping the work  20 , using the aforementioned formulas (3) to (5), based on the above-described respective values on the vibrations of the pawl structures  10 . 
     More specifically, the excitation force calculating portion  71  calculates the excitation force Fa acting on the first pawl structure  10   a , using the formula (3), based on the mass m 1  as the total mass, the damping coefficient c 1  as the total damping and the spring constant k 1  as the total rigidity, regarding the first pawl structure  10   a . Similarly, the excitation force calculating portion  71  calculates the excitation force Fb acting on the second pawl structure  10   b , using the formula (4), based on the mass m 2 , the damping coefficient c 2  and the spring constant k 2 , regarding the second pawl structure  10   b . The excitation force calculating portion  71  calculates the excitation force Ft acting on the third pawl structure  10   c , using the formula (5), based on the mass m 3 , the damping coefficient c 3  and the spring constant k 3 , regarding the third pawl structure  10   c.    
     As seen from the above, the respective values used for calculating the excitation forces acting on the respective pawl structures  10 , i.e., each values of the displacements due to the vibrations, the total mass, the total damping and the total rigidity of the pawl structures  10 , by the excitation force calculating portion  71 , are preliminarily set up and memorized in the storage portion or the like of the control system  70 . 
     Thus, the excitation force calculating portion  71  functions as the excitation force calculating means for calculating the excitation forces acting on the pawl structures  10  in the moving directions with rotation of the work rotating portion, based on the displacements of the pawl structures  10 , as well as the total mass of the pawl structures  10 , the total damping of the pawl structures  10  in the moving directions and the total rigidity of the pawl structures  10  in the moving directions, detected by the displacement sensors  50 . Specifically, the control system  70  functions as the excitation force calculating means by performing the predetermined calculation or the like according to the excitation force calculation program stored in the storage portion thereof. 
     The damping force calculating portion  72  calculates the forces of the opposite directions and the same sizes to the excitation forces calculated by the excitation force calculating portion  71 , as the damping forces acting on the pawl structures  10 . 
     The control system  70  carries out the predetermined calculations or the like according to the damping force calculation program stored in the storage portion thereof, whereby the calculations of the damping forces by the damping force calculating portion  72  are performed. Briefly, in the damping control for the pawl structures  10 , the damping forces acting on the respective pawl structures  10  that clamps the work  20  and receives the excitation forces with rotation of the work rotating portion are calculated by the damping force calculating portion  72 . 
     In the calculations of the damping forces acting on the pawl structures  10  by the damping force calculating portion  72 , the values of the excitation forces calculated by the excitation force calculating portion  71  are utilized. In other words, the damping force calculating portion  72  calculates the forces counteracting the excitation forces calculated by the excitation force calculating portion  71 , i.e., the forces of the opposite directions and the same sizes to the excitation forces calculated, as the damping forces acting on the pawl structures  10 . 
     Therefore, when the values of the excitation forces calculated by the excitation force calculating portion  71  are, for example, Fx (N), the damping force calculating portion  72  calculates the damping forces acting on the pawl structures  10  as −Fx (N). 
     More specifically, the damping force calculating portion  72  calculates the damping force (−Fa) to the excitation force Fa calculated by the excitation force calculating portion  71  (see the formula (3)), with respect to the first pawl structure  10   a . Similarly, the damping force calculating portion  72  calculates the damping force (−Fb) to the excitation force Fb (see the formula (4)), with respect to the second pawl structure  10   b , and calculates the damping force (−Fc) to the excitation force Fc (see the formula (5)), with respect to the third pawl structure  10   c.    
     As seen from the above, the damping force calculating portion  72  functions as the damping force calculating means for calculating the forces of the opposite directions and the same sizes to the excitation forces calculated by the excitation force calculating portion  71 , as the damping forces acting on the pawl structures  10 . Specifically, the control system  70  performs the given calculations or the like according to the damping force calculation program stored in the storage portion thereof, whereby the damping force calculating portion  72  functions as the aforementioned damping force calculating means. 
     The damping control portion  73  controls the solenoid changeover valves  52 , the supplying flow control valves  61  and the retracting flow control valves  62 , so that the damping forces calculated by the damping force calculating portion  72  exerts the pawl structures  10 . 
     The control system  70  carries out the given calculations or the like according to the damping control program stored in the storage portion thereof, whereby the controls of the solenoid changeover valves  52 , the supplying flow control valves  61  and the retracting flow control valves  62  by the damping control portion  73  are performed. Briefly, in the damping control of the pawl structures  10 , the directions and the largeness of the biasing forces for the pawl structures  10  by the respective cylinder mechanisms  30  are controlled, so that the damping forces on the respective pawl structures  10  calculated by the damping force calculating portion  72  exert the respective pawl structures  10 , by the controls of the respective solenoid changeover valves  52 , the respective supplying flow control valves  61  and the respective retracting flow control valves  62 , using the damping control portion  73 . 
     In the controls for the solenoid changeover valves  52  by the damping control portion  73 , the flow passages (the positions of the solenoid changeover valves  52 ) are switched, so that the directions of the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30  become the directions of the damping forces calculated by the damping force calculating portion  72  (the directions opposite to the ones of the excitation forces calculated by the excitation force calculating portion  71 . 
     Therefore, when the directions of the damping forces calculated by the damping force calculating portion  72  are the ones pulling the pawl structures  10  (− direction in the X-axis), the damping control portion  73  switches the solenoid changeover valves  52  to the positions P 1 . Meanwhile, the directions of the damping forces calculated by the damping force calculating portion  72  are the ones pushing the pawl structures  10  (+ direction in the X-axis), the damping control portion  73  switches the solenoid changeover valves  52  to the positions P 2 . 
     In the controls for the supplying flow control valves  61  and the retracting flow control valves  62  by the damping control portion  73 , the valve opening degrees of the respective flow control valves  61 ,  62  are controlled, so that the largeness of the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30  are the ones of the damping forces calculated by the damping force calculating portion  72  (the same largeness as the excitation forces calculated by the excitation force calculating portion  71 ). 
     The largeness of the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30  are the ones of the forces acting on the piston portions  14  of the pawl structures  10  by the cylinder mechanisms  30 . The values of the forces acting on the piston portions  14  are schematically calculated by the multiplications of the pressures (the hydraulic pressures) acting on the piston portions  14  and the effective areas in the piston portions  14 . 
     Therefore, when the biasing forces for the pawl structures  10  by the cylinder mechanisms  30  exert in the directions pulling the pawl structures  10 , the largeness of the biasing forces are calculated by the multiplications of the pressures acting from the first cylinder chambers  31   a  to the piston portions  14  and the areas (the effective areas) of the surfaces  14   a  on the sides forming the first cylinder chambers  31   a  of the piston portions  14  (see  FIG. 11  ( a )). When the biasing forces for the pawl structures  10  by the cylinder mechanisms  30  exert in the directions pushing the pawl structures  10 , the largeness of the biasing forces are calculated by the multiplications of the pressures acting from the second cylinder chambers  31   b  to the piston portions  14  and the areas (the effective areas) of the surfaces  14   b  on the sides forming the second cylinder chambers  31   b  of the piston portions  14  (see  FIG. 11  ( a )). 
     Briefly, the pressures acting on the piston portions  14  are controlled, so that the largeness of the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30  become the ones of the damping forces calculated by the damping force calculating portion  72 . The pressures acting on the piston portions  14  are adjusted by controlling the flow rates of the oils due to the supplying flow control valves  61  and the retracting flow control valves  62 . Hereinafter, with regard to the pressures acting on the piston portions  14 , the pressures that the largeness of the biasing forces acting on the pawl structures  10  by the cylinder mechanisms  30  become the ones of the damping forces calculated by the damping force calculating portion  72  are defined as “the adjustment pressures”. 
     In other words, the damping control portion  73  adjusts the valve opening degrees of the supplying flow control valves  61  and the retracting flow control valves  62 , so as to exert the adjustment pressures on the piston portions  14 . The adjustment pressures exerting on the piston portions  14  include friction resistances of the piston portions  14  in the cylinder mechanisms  30 , back pressure resistances so as to flow out the oils retracted from one cylinder chamber or the like. 
     In the controls (the adjustments of the valve opening degrees) of the supplying flow control valves  61  and the retracting flow control valves  62  by the damping control portion  73 , the discharge pressure of the oil pump  55 , the pressure losses in the pipings forming the respective oil passages of the first oil passage  53   a , the second oil passage  53   b , the supplying oil passage  54   a  and the retracting oil passage  54   b , the diameters of the pipings forming the respective oil passages or the like are considered. 
     In other words, the damping control portion  73  calculates the valve opening degrees of the respective supplying flow control valves  61  and the retracting flow control valves  62 , based on the respective values of the effective areas of the piston portions  14  (the areas of the above-mentioned surfaces  14   a ,  14   b ), the discharge pressure of the oil pump  55 , the pressure losses and the diameters in the pipings forming the respective oil passages, or the like, and controls the respective flow control valves  61 ,  62  so that they have calculated valve opening degrees. Incidentally, the respective values of the effective areas of the piston portions  14  or the like are preliminarily set up and memorized at the storage portion thereof or the like in the control system  70  when needed. 
     The controls of the solenoid changeover valves  52 , the supplying flow control valves  61  and the retracting flow control valves  62  by the damping control portion  73  as described above are independently performed for the respective valves provided with the respective cylinder mechanisms  30 . More specifically, the damping control portion  73  controls the first solenoid changeover valve  52   a , the first supplying flow control valve  61   a  and the first retracting flow control valve  62   a  provided with the first cylinder mechanism  30   a , with respect to the damping control for the first pawl structure  10   a . Similarly, the damping control portion  73  controls the second solenoid changeover valve  52   b , the second supplying flow control valve  61   b  and the second retracting flow control valve  62   b  provided with the second cylinder mechanism  30   b , with respect to the damping control for the second pawl structure  10   b . The damping control portion  73  controls the second solenoid changeover valve  52   b , the second supplying flow control valve  61   b  and the second retracting flow control valve  62   b  provided with the second cylinder mechanism  30   b , with respect to the damping control for the second pawl structure  10   b . The damping control portion  73  controls the third solenoid changeover valve  52   c , the third supplying flow control valve  61   c  and the third retracting flow control valve  62   c  provided with the third cylinder mechanism  30   c , with respect to the damping control for the third pawl structure  10   c.    
     Thus, the damping control portion  73  functions as the damping control means for controlling the solenoid changeover valves  52 , the supplying flow control valves  61  and the retracting flow control valves  62 , so that the damping forces calculated by the damping force calculating portion  72  exert the pawl structures  10 . Specifically, the control system  70  performs the predetermined calculations according to the damping control program stored in the storage portion thereof, whereby the damping control portion  73  functions as damping control means. 
     The damping control for the pawl structure  10  will be described, with reference to the flow diagram on the damping control for the pawl structure  10  as shown in  FIG. 12 . 
     In the damping control for the pawl structure  10 , first the work  20  is set up (Step S 200 ). Briefly, the flange portion  24   a  of the center housing  24  in the work  20  is fixed into the supporting recessed portion  3   b  forming the supporting surface  3   a  in the turbine housing portion  3 , so that the work  20  is supported on the supporting surface  3   a.    
     After the work  20  has been set up, the work  20  is on the clamped condition by the respective pawl structures  10  (Step S 210 ). Specifically, the pressure oils are supplied from the oil tank  56  to the first cylinder chambers  31   a  of the respective cylinder mechanisms  30  using the oil pump, whereby the respective pawl structures  10  are pulled and moved to the work fixing directions, so as to be on the engaged condition on the work  20  set up and to be biased to the work fixing directions. Accordingly, the clamping for the work  20  is finished. 
     In this regard, when the attitude control for the work  20  as mentioned above is performed, the clamping for the work  20  at the Step S 210  corresponds to that of the Step S 160  in the flow diagram as shown in  FIG. 4 . In this case, the solenoid valves  35  disposed with the respective cylinder mechanisms  30  (see  FIGS. 1 and 3 ) are provided with the first oil passages  53   a  or the supplying oil passages  54   a  as the pipings so as to supply the pressure oils to the first cylinder chambers  31   a.    
     When the clamping of the work  20  has been finished at the Step S 210 , the respective solenoid changeover valves  52  are on the position PN by the control system  70 . In other words, when the clamping of the work  20  has been finished, the supply/discharge of the oils are blocked in the respective cylinder mechanisms  30  and the oil pressures of the first cylinder chambers  31   a  and the second cylinder chambers  31   b  in the respective cylinder mechanisms  30  are constantly retained. 
     When the clamping of the work  20  has been finished, the rotation of the work rotating portion is started (Step S 220 ). In other word, the same compressed air as the discharge air from the engine is supplied to the turbine housing portion  3 , and, via the turbine rotor  22 , the work rotating portion including it is rotated at the unbalance correction rotation numbers. 
     When the work rotating portion is rotated at the unbalance correction rotation numbers, the sensor outputs are performed from the respective displacement sensors  50 , and the displacements Xa, Xb and Xc due to the vibrations of the respective pawl structures  10  are measured, based on the sensor outputs (Step S 230 ). In other words, after the work  20  has been on the clamped condition, the largeness of the gaps G 2  in the respective pawl structures  10  are measured based on the detection signals from the respective displacement sensors  50 . The displacements Xa, Xb and Xc due to the vibrations of the respective pawl structures  10  are measured, based on the measurements on the largeness of the gaps G 2  in the respective pawl structures  10 . 
     Subsequently, the excitation forces acting on the respective pawl structures  10  with the rotation of the work rotating portion are calculated, using the displacements Xa, Xb and Xc due to the vibrations of the respective pawl structures  10  measured at the Step S 230  (Step S 240 ). Specifically, the excitation forces acting on the respective pawl structures  10  clamping the work  20  are calculated, using the aforementioned formulas (3) to (5), based on the displacements Xa, Xb and Xc due to the vibrations of the respective pawl structures  10 , the total mass m 1 , m 2 , m 3 , the total damping c 1 , c 2 , c 3 , and the total rigidity k 1 , k 2 , k 3  of the respective pawl structures  10  by the excitation force calculating portion  71 . In this regard, the X in the formula (3) corresponds to the displacement Xa due to the vibration of the first pawl structure  10   a , and the X in the formula (4) corresponds to the displacement Xb due to the vibration of the second pawl structure  10   b , as well as the X in the formula (5) corresponds to the displacement Xc due to the vibration of the third pawl structure  10   c.    
     Next, the damping forces acting on the respective pawl structures  10  are calculated, using the excitation forces calculated at the Step S 240  (Step S 250 ). Briefly, by the damping force calculating portion  72 , the damping forces acting on the respective pawl structures  10  are calculated, as the forces counteracting the excitation forces, based on the excitation forces acting on the respective pawl structures  10 . 
     The switchings of the flow passages in the respective solenoid changeover valves  52  are performed, so that the damping forces calculated at the Step S 250  exert the respective pawl structures  10  (Step S 260 ). That is, the respective solenoid changeover valves  52  are switched at the position P 1  or P 2  by the damping control portion  73  so that the directions of the biasing forces acting on the respective pawl structures  10  by the cylinder mechanisms  30  become the ones of the damping forces calculated, whereby the switchings of the flow passages are performed. 
     The valve opening degrees of the respective supplying flow control valves  61  and the respective retracting flow control valves  62  are adjusted, so that the damping forces calculated at the Step S 250  exert the respective pawl structures  10  (Step S 270 ). Briefly, the valve opening degrees of the respective supplying flow control valves  61  and the respective retracting flow control valves  62  are adjusted by the damping control portion  73 , so that the largeness of the biasing forces acting on the respective pawl structures  10  by the cylinder mechanisms  30  become the ones of the damping forces calculated (so that the pressures acting on the piston portions  14  become the above-mentioned adjustment pressures), whereby the adjustments of the flow rates are performed. 
     The controls for the respective solenoid changeover valves  52 , the respective supplying flow control valves  61  and the respective retracting flow control valves  62 , based on the detection signals from the displacement sensors  50  as mentioned before (Steps, S 230  to S 270 ), i.e., the damping controls for the respective pawl structures  10  are performed, until the rotation of the work rotating portion is stopped (Step S 280 ). In this respect, the stopping of the rotation of the work rotating portion is detected by the rotation sensor  57 . 
     Thus, by the damping control for the respective pawl structures  10 , the reduction of the productivity in the production line of the turbocharger  2  can be prevented, and the vibrations of the respective pawl structures  10  as the members for fixing the work  20  on the turbine housing portion  3  can be restrained, thereby enhancing the accuracy in the unbalance correction. 
     More specifically, as mentioned above, the reduction of the productivity in the production line of the turbocharger  2  can be prevented, using the clamp method by the pawl structures  10  for fixing the work  20  on the turbine housing portion  3 . 
     The vibrations of the respective pawl structures  10  as the members for fixing the work  20  on the turbine housing portion  3  can be reduced, whereby the claming force for the work  20  (the force that the work  20  is pressed on the turbine housing portion  3 ) can be stabilized, so as to prevent the work  20  from vibrating largely with the rotation of the work rotating portion. As a result, the accuracy in the unbalance correction for the work  20  can be improved. 
     Incidentally, the unbalance correction device  1  of the present embodiment includes the displacement sensors  50  comprised as the contact-free gap sensors, as the displacement detecting means provided with the respective pawl structures  10 , but the displacement detecting means are not limited to this. As the displacement detecting means, the means that are provided with the respective pawl structures  10  and detect the displacements in the moving directions due to the vibrations of the pawl structures  10  clamping the work  20  on the turbine housing portion  3  to the device body with the rotation of the work rotating portion may be utilized. 
     As the displacement detecting means, for example, the other straight line position sensors, such as proximity switch or contact gap sensors, may be utilized, as long as they have enough accuracies (for example, the accuracies in the order of a few μm to a few dozens μm) to detect the displacements due to the vibrations of the pawl structures  10  clamping the work  20 . 
     The unbalance correction device  1  of the present embodiment includes the solenoid changeover valves  52  comprised as the solenoid control four ports changeover valves, as the direction switching means provided with the respective cylinder mechanisms  30 , but the direction switching means are not limited to them. As the direction switching means, the means that are provided with the respective cylinder mechanisms  30  and switch the moving and biasing directions in the moving directions of the pawl structures  10  by the cylinder mechanisms  30  may be utilized. 
     As the direction switching means, for example, the changeover valves having other constructions, such as the pilot operated changeover valves may be utilized. 
     The unbalance correction device  1  of the present embodiment includes the supplying flow control valves  61  and the retracting flow control valves  62  comprised as one-way restrictors having check valves, as the biasing force control means provides with the respective cylinder mechanisms  30 , but the biasing force control means are not limited to them. As the biasing force control means, the means that are provided with the respective clamping members  30  and control the biasing forces biasing the pawl structures  10  by the cylinder mechanisms  30 , in the moving and biasing directions of the pawl structures  10  defined by the solenoid changeover valves  52  may be utilized. 
     As the biasing force control means, for example, the flow control valves having other constructions, such as the flow control valves may be utilized. 
     The second embodiment of the unbalance correction device according to the present invention will be described. Incidentally, the descriptions of the portions common to the unbalance correction device  1  of the first embodiment are arbitrarily abbreviated, using the same referential marks or the like. 
     As shown in  FIG. 13 , an unbalance correction device  81  according to the present embodiment includes magnetic fluid cylinder mechanisms  83  comprised as fluid pressure cylinder mechanisms using magnetic fluid as working fluids, in place of the cylinder mechanisms  30  in the unbalance correction device  1  of the first embodiment as described above. Specifically, the magnetic fluid cylinder mechanisms  83 , which are provided with the respective pawl structures  10 , function as the moving and biasing means for moving the pawl structures  10  in the moving directions and for biasing the pawl structures  10  on the engaged condition to the work fixing directions. 
     In the magnetic fluid cylinder mechanisms  83 , magnetic fluid  84  are used, as the working fluids filled in the cylinder cases  31  forming the first cylinder chambers  31   a  and the second cylinder chambers  31   b  via the piston portions  13  of the rod portions  12  in the pawl structures  10 . 
     In this regard, the magnetic fluid means the fluids having both behaviors of liquidities as liquid property and ones as magnetic body. Specifically, in the magnetic fluid, magnetic microparticles having approximately 10 nm in diameter, such as magnetite, ferrite such as manganese-zinc ferrite, iron, nickel, cobalt are diffused into solvent such as water, organic solvent, paraffin, by the action of surfactant agent. 
     The magnetic fluid cylinder mechanisms  83  are constituted as the double-acting cylinders similar to the cylinder mechanisms  30 . More specifically, as shown in  FIG. 13 , the first cylinder chambers  31   a  in the magnetic fluid cylinder mechanism  83  are continuously connected at the doorways of the magnetic fluid thereof to the first flow passages  82   a . The supplies of the magnetic fluid to the first cylinder chambers  31   a  and the discharges (the retractions) of the magnetic fluid  84  from the first cylinder chambers  31   a  are performed, via the first flow passages  82   a . Similarly, the second cylinder chambers  31   b  are continuously connected at the doorways of the magnetic fluid thereof to the second flow passages  82   b . The supplies of the magnetic fluid to the second cylinder chambers  31   b  and the discharges (the retractions) of the magnetic fluid  84  from the second cylinder chambers  31   b  are performed, via the second flow passages  82   b.    
     As shown in  FIG. 13 , the first flow passages  82   a  and the second flow passages  82   b  provided with the respective magnetic fluid cylinder mechanisms  83  are connected via a pump  85  to a tank  86 . In other words, magnetic fluid  86   a  are stored in the tank  86 , and the stored magnetic fluid  86   a  are supplied via the first flow passages  82   a  or the second flow passages  82   b  to the respective magnetic fluid cylinder mechanisms  83 , using the pump  85 . The magnetic fluid returned from the magnetic fluid cylinder mechanisms  83  are retracted via the first flow passages  82   a  or the second flow passages  82   b  to the tank  86 . 
     Hereinafter, when three magnetic fluid cylinder mechanisms  83  are distinctly described according to the pawl structures  10  supporting in the moving and biasing manner, the magnetic fluid cylinder mechanism  83  supporting the first pawl structure  10   a  in the moving and biasing manner is defined as “the first magnetic fluid cylinder mechanism  83   a ”, and the magnetic fluid cylinder mechanism  83  supporting the second pawl structure  10   b  in the moving and biasing manner is defined as “the second magnetic fluid cylinder mechanism  83   b ”, as well as the magnetic fluid cylinder mechanism  83  supporting the third pawl structure  10   c  in the moving and biasing manner is defined as “the third magnetic fluid cylinder mechanism  83   c”.    
     Thus, in the unbalance correction device  81  equipped with the magnetic fluid cylinder mechanisms  83  as constructions supporting the pawl structures  10  in the moving and biasing manner, during the unbalance correction, the damping controls for restraining the natural frequencies (behaviors) of the respective pawl structures  10  to the device body are performed, by acting the damping forces due to the viscous resistances of the magnetic fluid in the magnetic fluid cylinder mechanisms  83  on the respective pawl structures  10 , as the forces counteracting the excitation forces acting on the respective pawl structures  10  with the rotation of the work rotating portion. This is based on the following principle and behaviors of the magnetic fluid. 
     More specifically, the pawl structures  10  supported via the magnetic fluid  84  into the cylinder cases  31  in the magnetic fluid cylinder mechanisms  83  receive the viscous resistances caused by the relative movements thereof to the magnetic fluid  84 , due to the vibrations thereof. The viscous resistances convert the kinetic energies of the pawl structures  10  into the heat energies, and act the damping forces on the pawl structures  10 . Therefore, the viscous resistances to the pawl structures  10 , i.e., the largeness of the damping forces exerting the pawl structures  10  are varied, by the changes in the viscosities of the magnetic fluid  84 . 
     Meanwhile, the magnetic fluid changes the fluidities, i.e., the viscosities (the apparent viscosities) in accordance with the intensities of applied magnetic field, as behaviors thereof. This is based on the fact that when the flowing magnetic fluid receives the actions of magnetic field, the particles move to be chained in the directions of magnetic field, due to the magnetic dipole interaction of the magnetic microparticles. 
     Consequently, the unbalance correction device  1  of the present embodiment applies the magnetic field to the magnetic fluid  84  into the cylinder cases  31  in the cylinder mechanisms  83  and changes the intensities of the magnetic field so as to change the apparent viscosities of the magnetic fluid  84 , as well as the device  1  acts the damping forces counteracting the excitation forces acting on the respective pawl structures  10  with the rotation of the work rotating portion, thereby performing the damping controls for restraining the vibrations of the respective pawl structures  10 . The unbalance correction device  81  of the present embodiment comprises the following constructions so as to perform the damping controls for the respective pawl structures  10 . 
     As shown in  FIG. 13 , in the unbalance correction device  81 , the respective pawl structures  10  are provided with the displacement sensors  50 . In other words, the unbalance correction device  81  of the present embodiment includes three displacement sensors  50 . Incidentally, in  FIG. 13 , for convenience of explanation, the position of the third magnetic fluid cylinder mechanism  83   c  in the unbalance correction device  81  is represented at slightly different spaces from the original position (see  FIG. 2 ). The displacement sensors  50  provided with the unbalance correction device  81  of the present embodiment, which are common portions to the unbalance correction device  1  of the first embodiment, will be not described. 
     As shown in  FIG. 13 , in the unbalance correction device  81 , the respective magnetic fluid cylinder mechanisms  83  have cylinder coils  87 . In other words, the unbalance correction device  81  of the present embodiment has three cylinder coils  87 . 
     The cylinder coils  87  are so-called solenoid coils and are provided to be wound around the cylinder cases  31 . Briefly, when the electric currents are carried on the cylinder coils  87 , the magnetic field are applied to the magnetic fluid  84  into the cylinder cases  31  in the axial directions of the cylinder cases  31  (in the lateral directions in  FIG. 13 ). 
     The largeness of the electric currents (The current value) carrying on the cylinder coils  87  are changed, whereby the intensities of magnetic field applied to the magnetic fluid  84  into the cylinder cases  31  are varied. Accordingly, the apparent viscosities (the fluidities) of the magnetic fluid  84  into the cylinder cases  31  are changed, thereby varying the largeness of the damping forces acting on the vibrating pawl structures  10 . 
     Thus, the cylinder coils  87  are provided with the respective magnetic fluid cylinder mechanisms  83  and function as the magnetic field applying means for applying the magnetic field to the magnetic fluid  84 . 
     Hereinafter, when three cylinder coils  87  are distinctly described according to the magnet fluid cylinder mechanisms  83  provided, the cylinder coil  87  provided with the first magnet fluid cylinder mechanism  83   a  is defined as “the first cylinder coil  87   a ”, and the cylinder coil  87  provided with the second magnet fluid cylinder mechanism  83   b  is defined as “the second cylinder coil  87   b ”, as well as the cylinder coil  87  provided with the third magnet fluid cylinder mechanism  83   c  is defined as “the third cylinder coil  87   c”.    
     The control construction of the pawl structures  10 , in the unbalance correction device  81  of the present embodiment equipped with the above-mentioned constructions, will be described, with reference to  FIG. 14 . 
     As shown in  FIG. 14 , the unbalance correction device  81  of the present embodiment includes a control system  90  for performing the damping control of the pawl structures  10 . The control system  90  controls the intensities of magnetic field applied to the magnetic fluid  84  in the cylinder cases  31  by the respective cylinder coils  87  based on the detection signals output from the respective displacement sensors. Substantively, the intensities of magnetic field applied to the magnetic fluid  84  in the cylinder cases  31  by the respective cylinder coils  87  are controlled, by adjusting the largeness of electric currents (the current values) supplied (input) from the control system  90  to the cylinder coils  87 . Accordingly, the damping forces acting on the pawl structures  10  in the magnetic fluid cylinder mechanisms  83  are controlled, thereby damping the vibrations of the pawl structures  10  to the device body (the turbine housing portion  3 ). 
     The control system  90  is connected to the respective displacement sensors  50  via signal line or the like. The control system  90  is connected to the respective cylinder coils  87  via lead wires or the like. The control system  90  receives signals on displacements due to the vibrations of the pawl structures  10  clamping the work  20 , detected by the respective displacement sensors  50 . Accordingly, the control system  90  acquires information on the displacements due to the vibrations of the pawl structures  10  clamping the work  20 . The control system  90  supplies electric currents to the respective cylinder coils  87  and controls the largeness of the electric currents depending on those of the magnetic field applied to the magnetic fluid  84 . 
     The control system  90  independently controls the electric currents supplied to the respective cylinder coils  87 , based on the detection signals from the respective displacement sensors  50 . More specifically, the control system  90  controls the electric currents supplied to the first cylinder coil  87   a , based on the detection signal from the first displacement sensor  50   a , and controls the electric currents supplied to the second cylinder coil  87   b , based on the detection signal from the second displacement sensor  50   b , as well as controls the electric currents supplied to the third cylinder coil  87   c  based on the detection signal from the third displacement sensor  50   c . Accordingly, the magnetic fluid cylinder mechanisms  83 , which acts the pawl structures  10  clamping the work  20  on the damping forces due to the vibrations thereof, are independently controlled, thereby damping the vibrations of the respective pawl structures  10  to the device body (the turbine housing portion  3 ). 
     The control system  90  is connected to the rotation sensor  57 . The control system  90  receives a signal on rotational displacement (rotational angle) of the work rotating portion in the work  20  on the clamped condition, detected by the rotation sensor  57 . Accordingly, the control system  90  acquires information on the rotational displacement (the rotational angle) of the work rotating portion in the work  20  on the clamped condition. 
     The control system  90  has a storage portion which stores a program or the like, an expanding portion which expands the program or the like, a calculating portion which performs the predefined calculation according to the program or the like, a filing portion which files the calculated results or the like by the calculating portion, a measuring portion which measures the displacements due to the vibrations of the pawl structures  10  clamping the work  20  or the like, based on the detection signals output from the displacement sensors  50 , a power supplying portion which supplies (input) the electric currents to the cylinder coils  87 . The program or the like stored in the storage portion include after-mentioned damping calculation program, a damping control program and data on the relationship between the intensities of the magnetic field applied to the magnetic fluid  84  by the cylinder coils  87  and the total damping (the damping coefficient) of the pawl structures  10  in the moving directions. 
     As the control system  90 , specifically, the construction that a CPU, a ROM, a RAM, a HDD or the like are connected together with a bus, or the configuration making up of one-chip LSI or the like are utilized. The control system  90  of the present embodiment, which is exclusive goods, is also substitutable for the one which the aforementioned program or the like are stored in the commercially available personal computer, workstation and so forth. 
     The control system  90  has a data memorizing portion  91 , a damping calculating portion  92  and a damping control portion  93 . 
     The data memorizing portion  91  memorizes pre-calculated data on the relationship between the intensities of the magnetic field applied to the magnetic fluid  84  by the cylinder coils  87  and the total damping (the damping coefficient) (hereinafter, referred to as “data on the relationship between the intensities of the magnetic field and the damping”. 
     The data memorizing portion  91  memorizes data on the relationship between electric current values I supplied to the cylinder coils  87  and viscosity μ of the magnetic fluid  84 , as data on the relationship between the intensities of the magnetic field and the damping. 
     In other words, as mentioned above, the intensities of the magnetic field applied to the magnetic fluid  84  by the cylinder coils  87  depend on the largeness of the electric currents flowing along the cylinder coils  87 . The damping coefficient due to the vibrations of the pawl structures  10  is a proportional constant to the vibration velocity on the damping forces (the viscous damping forces) acting on the vibrating pawl structures  10 , and become the viscous resistance (the viscous damping) for the vibrating pawl structures  10 , i.e., the viscosity (the viscous coefficient) μ of the magnetic fluid  84 . In this regard, the data memorizing portion  91  memorizes the data on the relationship between the intensities of the magnetic field and the damping in the respective magnetic fluid cylinder mechanisms  83 , as the pre-calculated data on the relationship between the electric current values I supplied to the cylinder coils  87  and the viscosity μ of the magnetic fluid  84  (hereinafter, referred to as “the relationship between the electric current values I and the viscosity μ”. 
     The relationship between the electric current values I and the viscosity μ, for example, becomes the one as shown in  FIG. 15 . In this example, the relationship between the electric current values I and the viscosity μ is the proportional one, and the graph showing the relationship between the electric current values I and the viscosity μ becomes in a linear fashion. This is based on the fact that the magnetization curve showing the relationship between the magnetic field and the magnetization of the magnetic fluid  84 , which shows non-ferromagnetic properties, becomes in a linear fashion. In other words, the magnetic field and the magnetization are proportional in the magnetic body, which shows non-ferromagnetic property. The magnetic field is substitutable for the supply currents to the cylinder coils  87  (the electric current values I), and the magnetization is substitutable for the viscosity μ of the magnetic fluid  84 . Briefly, the magnetic fluid  84  used as the working fluids in the magnetic fluid cylinder mechanisms  83  of the present embodiment show non-ferromagnetic properties, and the relationship between the electric current values I and the viscosity μ becomes the proportional one, as shown in  FIG. 15 . The relationship between the electric current values I and the viscosity μ in the magnetic fluid  84  is preliminarily calculated, and is memorized as, for example, mapped data in the data memorizing portion  91 . Thus, the data on the relationship between the intensities of the magnetic field and the damping are memorized as the ones on the relationship between the electric current value I and the viscosity μ of the magnetic fluid  84 , in the data memorizing portion  91 . 
     In this respect, as shown in  FIG. 15 , the viscosity μ 0  when the electric current value I is zero is the one of the magnetic fluid  84  when the magnetic field is not applied to the magnetic fluid  84  in the respective magnetic fluid cylinder mechanisms  83  (during the non-magnetic field). In other words, the viscosity μ 0  becomes the default value on the viscosity μ of the magnetic fluid  84 . 
     The data memorizing portion  91  memorizes the data on the relationship between the electric current values I and the viscosity μ, in the respective magnetic fluid cylinder mechanisms  83 . 
     More specifically, the data memorizing portion  91  memorizes the data on the relationship between the electric current value I supplied to the first cylinder coil  87   a  and the viscosity μ of the magnetic fluid  84  into the cylinder case  31  in the first magnetic fluid cylinder mechanism  83   a , with respect to the first magnetic fluid cylinder mechanism  83   a . Similarly, the data memorizing portion  91  memorizes the data on the relationship between the electric current value I supplied to the second cylinder coil  87   b  and the viscosity μ of the magnetic fluid  84  in the second magnetic fluid cylinder mechanism  83   b , with respect to the second magnetic fluid cylinder mechanism  83   b , and the data memorizing portion  91  memorizes the data on the relationship between the electric current value I supplied to the third cylinder coil  87   c  and the viscosity μ of the magnetic fluid  84  in the third magnetic fluid cylinder mechanism  83   c , with respect to the third magnetic fluid cylinder mechanism  83   c.    
     As described above, the data memorizing portion  91  functions as the memorizing means for memorizing the pre-calculated data on the relationship between the intensity of the magnetic field and the damping. Specifically, the control system  90  memorizes the data on the relationship between the intensity of the magnetic field and the damping in the ROM or the like, whereby the data memorizing portion  91  functions as the memorizing means. 
     The damping calculating portion  92  calculates the total damping (the damping coefficient) of the pawl structures  10  in the moving directions, by which the excitation forces acting on the pawl structures  10  in the moving directions with the rotation of the work rotating portion are counteracted, based on the displacements of the pawl structures  10  detected by the displacement sensors  50 , as well as the total mass of the pawl structures  10  and the total rigidity of the pawl structures  10  in the moving directions. 
     The control system  90  performs the given calculations or the like according to the damping calculation program stored in the storage portion thereof, whereby the damping coefficients are calculated by the damping calculating portion  92 . Briefly, in the damping control for the pawl structures  10 , the total damping, by which the excitation forces acting on the respective pawl structures  10  clamping the work  20  with the rotation of the work rotating portion are counteracted, are calculated by the damping calculating portion  92 . In other words, the damping coefficients of the pawl structures  10  correspond to the damping ones calculated by the damping calculating portion  92 , so that the excitation forces acting on the pawl structures  10  are counteracted. 
     The respective values such as the displacements due to the vibrations of the pawl structures  10  detected by the displacement sensors  50 , the total mass and the total rigidity of the pawl structures  10  are utilized for calculating the damping coefficients by the damping calculating portion  92 . That is to say, the damping calculating portion  92  calculates the damping coefficients of the pawl structures  10 , by which the excitation forces acting on the pawl structures  10  with the rotation of the work rotating portion are counteracted (by which the values of excitation forces become zero) (hereinafter, referred to as “the damping coefficients counteracting the excitation forces”. 
     Therefore, the damping calculating portion  92  calculates the damping coefficients counteracting the excitation forces acting on the respective pawl structures  10 , assuming that the excitation forces acting on the respective pawl structures  10  are zero, i.e, if the respective Fa, Fb, and Fc are the following values: Fa=0, Fb=0, Fc=0 in each of the aforementioned formulas (3) to (5). More specifically, the damping calculating portion  92  calculates the damping coefficients counteracting the excitation forces acting on the respective pawl structures  10 , according to the following formulas (6) to (8) derived if the respective Fa, Fb, and Fc are the following values: Fa=0, Fb=0, Fc=0 in each of the aforementioned formulas (3) to (5), when the damping coefficient counteracting the excitation forces acting on the first pawl structure  10   a  is Ca, and the damping coefficient counteracting the excitation forces acting on the second pawl structure  10   b  is Cb, as well as the damping coefficient counteracting the excitation forces acting on the third pawl structure  10   c  is Cc. 
     
       
         
           
             
               
                 
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     Incidentally, since the values of the damping coefficients Ca, Cb and Cc of the respective pawl structures  10  are the ones corresponding to the viscosities (the viscous coefficients) of the magnetic fluid  84  as mentioned above, they become absolute values (positive values). 
     Thus, the damping calculating portion  92  calculates the damping coefficients counteracting the excitation forces acting on the respective pawl structures  10 , using the above-mentioned formulas (6) to (8), based on the respective values such as the displacements due to the vibrations of the pawl structures  10  detected by the displacement sensors  50 , the total mass and the total rigidity of the pawl structures  10 . 
     More specifically, the damping calculating portion  92  calculates the damping coefficient Ca counteracting the excitation forces acting on the first pawl structures  10   a , using the formula (6), based on the displacement Xa detected by the displacement sensor  50 , the mass m 1  as the total mass and the spring constant k 1  as the total rigidity, with respect to the first pawl structure  10   a . Similarly, the damping calculating portion  92  calculates the damping coefficient Cb counteracting the excitation forces acting on the second pawl structures  10   b , using the formula (7), based on the displacement Xb detected by the displacement sensor  50 , the mass m 2  as the total mass and the spring constant k 2  as the total rigidity, with respect to the second pawl structure  10   b . The damping calculating portion  92  calculates the damping coefficient Cc counteracting the excitation forces acting on the third pawl structures  10   c , using the formula (8), based on the displacement Xc detected by the displacement sensor  50 , the mass m 3  as the total mass and the spring constant k 3  as the total rigidity, with respect to the third pawl structure  10   c.    
     The damping coefficients acting on the respective pawl structures  10  that receive the excitation forces with the rotation of the work rotating portion correspond to the damping ones calculated by the damping calculating portion  92  as described above, thereby changing the damping forces acting on the pawl structures  10  and counteracting the excitation forces acting on the pawl structures  10 . 
     As seen from the above, the damping calculating portion  92  functions as the damping calculating means for calculating the total damping (the damping coefficients) of the pawl structures  10  in the moving directions, which counteract the excitation forces acting on the pawl structures  10  in the moving directions with the rotation of the work rotating portion, based on the displacements of the pawl structures  10  detected by the displacement sensors  50 , as well as the total mass of the pawl structures  10  and the total rigidity of the pawl structures  10  in the moving directions. Specifically, the control system  90  performs the given calculations or the like according to the damping calculation program stored in the storage portion thereof, whereby the damping calculating portion  92  functions as the damping calculating means. 
     The damping control portion  93  controls the cylinder coils  87 , so that the intensities of the magnetic field applied to the magnetic fluid  84  become the ones of the magnetic field corresponding to the total damping (the damping coefficients) calculated by the damping calculating portion  92 , based on the data on the relationship between the intensities of the magnetic field and the damping memorized in the data memorizing portion  91 . 
     The control system  90  performs the predetermined calculations or the like according to the damping control programs stored in the storage portion thereof, whereby, the aforementioned controls of the cylinder coils  87  by the damping control portion  93 , specifically, the controls of the electric currents flowing along the cylinder coils  87  are performed. In other words, in the damping controls for the pawl structures  10 , the largeness of the electric currents supplied to the respective cylinder coils  87  are controlled by the damping control portion  93 , so that the intensities of the magnetic field applied to the magnetic fluid  84  in the cylinder cases  31  are controlled. Accordingly, the viscosities (the viscous coefficients) μ of the magnetic fluid  84 , i.e., the damping coefficients are controlled, thereby controlling the largeness of the damping forces (the viscous damping forces) acting on the pawl structures  10  receiving the actions of the excitation forces. 
     When the cylinder coils  87  are controlled by the damping control portion  93 , the data on the relationship between the electric current values I and the viscosities μ memorized in the data memorizing portion  91  are utilized, so that the electric current values I supplied to the cylinder coils  87  are calculated. As the viscosities μ corresponding to the electric current values I supplied to the cylinder coils  87 , i.e., the damping coefficients, the values of the damping coefficients calculated by the damping calculating portion  92  are utilized. Specifically, as shown in  FIG. 15 , when the viscosities corresponding to the values of the damping coefficients calculated by the damping calculating portion  92  are μx, the electric currents of the electric current values Ix corresponding to the viscosities μx are supplied to the cylinder coils  87 , based on the relationship between the electric current values I and the viscosities μ memorized in the data memorizing portion  91 . 
     The electric currents of the electric current values corresponding to the values of the damping coefficients (the values of the viscosities) calculated by the damping calculating portion  92  flow along the cylinder coils  87 , so that the intensities of the magnetic field applied to the magnetic fluid  84  become the ones of the magnetic field corresponding to the total damping (the damping coefficients) calculated by the damping calculating portion  92 . Accordingly, the values of the damping forces (the viscous damping forces) acting on the pawl structures  10  become the ones counteracting the excitation forces acting on the pawl structures  10 , due to the viscosity changes of the magnetic fluid  84 . 
     The controls for the cylinder coils  87  by the damping control portion  93  as mentioned above are independently performed in each of the cylinder coils  87  provided with the respective magnetic fluid cylinder mechanisms  83 . More specifically, the damping control portion  93  controls (the electric currents supplied to) the first cylinder coil  87   a  provided with the first magnetic fluid cylinder mechanism  83   a , with respect to the damping control for the first pawl structures  10   a . Similarly, the damping control portion  93  controls the second cylinder coil  87   b  provided with the second magnetic fluid cylinder mechanism  83   b , with respect to the damping control for the second pawl structures  10   b , and the damping control portion  93  controls the third cylinder coil  87   c  provided with the third magnetic fluid cylinder mechanism  83   c , with respect to the damping control for the third pawl structures  10   c.    
     Thus, the damping control portion  93  functions as the damping control means for controlling the cylinder coils  87 , so that the intensities of the magnetic field applied to the magnetic fluid  84  become the one of the magnetic field corresponding to the total damping (the damping coefficients) calculated by the damping calculating portion  92 . Specifically, the control system  90  performs the given calculations or the like according to the damping control programs stored in the storage portion thereof, whereby the damping control portion  93  functions as the damping control means. 
     The damping controls for the pawl structures  10  will be described, with reference to the flow diagram of the damping control for the pawl structures  10  as shown in  FIG. 16 . 
     In the damping control for the pawl structure  10 , first the work  20  is set up (Step S 300 ). The work  20 , which is set up, is on the clamped condition by the respective pawl structures  10  (Step S 310 ). More specifically, the magnetic fluid are pumped from the tank  86  to the first cylinder chamber  31   a  the respective magnetic fluid cylinder mechanisms  83  using the pump  85 , whereby the respective pawl structures  10  are pulled and moved to the work fixing directions, so as to be on the engaged condition to the work  20  set up and be biased to the work fixing directions. Accordingly, the clamping of the work  20  is finished. 
     In this regard, the clamping of the work  20  at the Step S 310  corresponds to the one at the Step S 160  in the flow diagram as shown in  FIG. 4 . In this case, the solenoid valves  35  provided with the respective magnetic fluid cylinder mechanisms  83  (see  FIGS. 1 and 3 ) are provided with the first flow passage  82   a  as the piping for supplying the pressure oils to the first cylinder chamber  31   a.    
     At the Step S 310 , when the clamping of the work  20  has been finished, the supplies/discharges of the magnetic fluid to the respective magnetic fluid cylinder mechanisms  83  are blocked by the valve mechanisms (not shown), and the pressures of the magnetic fluid into the first cylinder chamber  31   a  and the second cylinder chamber  31   b  in the respective magnetic fluid cylinder mechanisms  83  are kept constant. 
     After the clamping of the work  20  has been finished, the rotation of the work rotating portion is started (Step S 320 ). 
     When the work rotating portion are rotated at the unbalance correction rotation numbers, the sensor outputs are performed from the respective displacement sensors  50 , and the displacements Xa, Xb and Xc due to the vibrations of the respective pawl structures  10  are measured, based on the sensor outputs (Step S 330 ). 
     Subsequently, the damping coefficients counteracting the excitation forces are calculated, based on the displacements Xa, Xb and Xc due to the vibrations of the respective pawl structures  10  measured at the Step S 330  (Step S 340 ). Specifically, by the damping calculating portion  92 , damping coefficients ca, cb and cc counteracting the excitation forces acting on the respective pawl structures  10  are calculated, using the aforementioned formulas (6) to (8), based on the displacements Xa, Xb and Xc due to the vibrations of the pawl structures  10  detected by the displacement sensors  50 , the total mass m 1 , m 2  and m 3  and the total rigidity k 1 , k 2  and k 3  of the respective pawl structures  10 . 
     Next, the largeness of the electric currents supplied to the respective cylinder coils  87  are determined, according to the damping coefficients calculated at the Step S 340  (Step S 350 ). Specifically, the electric current values Ia, Ib and Ic corresponding to the values of the damping coefficients (the values of the viscosities) calculated by the damping calculating portion  92  are determined by the damping control portion  93 , based on the data on the relationship between the electric current values I and the viscosities μ memorized in the data memorizing portion  91 . In this regard, the electric current value Ia is the value of the first cylinder coil  87   a , and the electric current value Ib is the value of the second cylinder coil  87   b , as well as the electric current value Ic is the value of the third cylinder coil  87   c.    
     The electric currents of the electric current values determined at the Step S 350  are supplied to the respective cylinder coils  87  (Step S 360 ). Specifically, from the power supplying portion in the control system  90 , the electric current of the electric current value Ia is supplied to the first cylinder coil  87   a , and the electric current of the electric current value Ib is supplied to the second cylinder coil  87   b , as well as the electric current of the electric current value Ic is supplied to the third cylinder coil  87   c , respectively. 
     Accordingly, the magnetic field are applied to the magnetic fluid  84  in the respective magnetic fluid cylinder mechanisms  83 , and the viscosities of the magnetic fluid  84  are increased, thereby acting the damping forces (the viscous damping forces) on the respective pawl structures  10 . In this respect, the intensities of the magnetic field applied to the magnetic fluid  84  are the ones of the magnetic field corresponding to the total damping (the damping coefficients) calculated by the damping calculating portion  92 , and the damping forces acting on the respective pawl structures  10  become the largeness counteracting the excitation forces acting on the pawl structures  10 . 
     The controls for (the electric currents supplied to) the respective cylinder coils  87  based on the detection signals from the displacement sensors  50  (Steps S 330  to S 360 ), i.e., the damping controls for the respective pawl structures  10  are performed, until the rotation of the work rotating portion is stopped (Step S 370 ). In this respect, the stopping in the rotation of the work rotating portion is detected by the rotation sensor  57 . 
     As described above, the unbalance correction device  81  of the present embodiment performing the damping controls for the respective pawl structures  10  can achieve the effect of simplifying the device configuration, in addition to the effect obtained in case of the first embodiment. 
     More specifically, the damping controls for the respective pawl structures  10  in the present embodiment are performed, only by the electric controls for the respective cylinder coils  87 , with the supplies/discharges of the magnetic fluid to the respective magnetic fluid cylinder mechanisms  83  stopped. Consequently, in the damping controls for the respective pawl structures  10 , the valve mechanisms such as the changeover valves, the flow control valves, so as to switch the supplies/discharges of the magnetic fluid to the magnetic fluid cylinder mechanisms  83  and control the flow rate thereof, are not needed. Accordingly, the effect of simplifying the device configuration can be achieved. 
     Incidentally, the unbalance correction device  81  of the present embodiment comprises the cylinder coils  87  wound around the cylinder cases  31 , as the magnetic field applying means provided with the respective magnetic fluid cylinder mechanisms  83 , but the magnetic field applying means are not limited to them. The means, which are provided with the respective magnetic fluid cylinder mechanisms  83  and apply the magnetic field to the magnetic fluid  84  into the cylinder cases  31 , may be utilized, as the magnetic field applying means. 
     As the magnetic field applying means, for example, the construction that the cylinder coils are incorporated into the cylinder cases  31 , the construction that conduit lines, which are continuously connected to at least any of the first cylinder chamber  31   a  and the second cylinder chamber  31   b  in the cylinder cases  31  and which flow the magnetic fluid to them, are differently provided from the main body of the cylinder cases  31 , as well as the cylinder coils are wound around the conduit lines or the like may be utilized. In the present embodiment, the directions of the magnetic field applied to the magnetic fluid  84  into the cylinder cases  31  by the cylinder coils  87  are the axial ones of the cylinder cases  31  (the lateral directions in  FIG. 13 ), but the directions of the magnetic field applied to the magnetic fluid  84  are not especially limited. 
     Industrial Applicability 
     The present invention is applicable in the unbalance correction device of the high-speed rotary apparatus used for correcting the unbalance of the rotating portion thereof, with respect to the high-speed rotary apparatus having the rotating portion rotating at relatively high speed, such as the turbocharger equipped with, for example, the automobile engine.