Patent Publication Number: US-2012023938-A1

Title: Variable capacity supercharger for internal combustion engine

Description:
TECHNICAL FIELD 
     The present invention relates to a variable capacity supercharger for an internal combustion engine capable of varying a supercharging efficiency by operating movable vanes. 
     BACKGROUND ART 
     There is known a variable geometry type supercharger, as a supercharger to be used for an internal combustion engine, to vary a supercharging efficiency by arranging a plurality of movable vanes at a diffuser portion of a compressor so as to be circularly aligned and operating the movable vanes (e.g., see Patent Document 1). In addition, there are Patent Document 2 and Patent Document 3 as prior art references in relation to the present invention.
     Patent Document 1: JP-A-2005-163691   Patent Document 2: JP-A-08-254127   Patent Document 3: JP-A-2006-169985   

     SUMMARY OF INVENTION 
     Technical Problem 
     Here, it is assumed that the above variable geometry type compressor is combined with a variable nozzle type turbocharger to drive movable vanes of a turbine with an actuator. When it is configured to drive the movable vanes at the turbine side and the movable vanes at the compressor side respectively with a separate actuator, there is a problem that mounting space for the supercharger is increased as the drive mechanism being upsized to have two actuators. 
     In view of the foregoing, one object of the present invention is to provide a variable capacity supercharger for an internal combustion engine capable of suppressing upsizing of the drive mechanism when the turbine and compressor are respectively provided with a movable vane mechanism. 
     Solution to Problem 
     A variable capacity supercharger of the present invention includes: a turbine including an exhaust-side movable vane mechanism which varies cross-sectional area of a flow path of exhaust gas introduced into a turbine wheel by open-close operation of a movable vane; a compressor including an intake-side movable vane mechanism which varies cross-sectional area of a flow path of intake air delivered from a compressor wheel by open-close operation of a movable vane; and a drive mechanism having an actuator used in common by the exhaust-side movable vane mechanism and the intake-side movable vane mechanism to perform open-close operation of the movable vane of each movable vane mechanism as transmitting operation of the actuator to both of the movable vane mechanisms. 
     According to the variable capacity supercharger of the present invention, since the respective movable vanes of the exhaust-side movable vane mechanism and the intake-side movable vane mechanism are driven by the common actuator, the number of the actuators can be reduced compared to a case of disposing a dedicated actuator for each movable vane mechanism. Therefore, it is possible to reduce space required for mounting the supercharger as suppressing upsizing of the drive mechanism against the movable vane mechanism. 
     In one embodiment of the supercharger of the present invention, the drive mechanism and operation input portions of both of the movable vane mechanisms may be respectively connected so that the movable vane of the intake-side movable vane mechanism is operated in the opening direction as well when the movable vane of the exhaust-side movable vane mechanism is operated in the opening direction; and at least either the exhaust-side movable vane mechanism or the intake-side movable vane mechanism may be provided with a device which lowers drive force in the opening direction to be added to the operation input portion when operating the movable vane in the opening direction than drive force in the closing direction to be added to the operation input portion when operating the movable vane in the closing direction. According to this embodiment, it is possible to operate the movable vane of the exhaust-side movable vane mechanism and the movable vane of the intake-side movable vane mechanism with the common actuator in the same direction. In addition, since the device to lower the drive force in the opening direction than the drive force in the closing direction of at least one of the movable vane mechanisms is provided, the drive force in the opening direction to be added to the respective operation input portions of the two movable vane mechanisms can be sufficient as being less compared to a case of omitting the device. Accordingly, the output power required for the actuator can be reduced, thereby enabling to achieve downsizing of the actuator, and then, to further achieve downsizing of the supercharger. Here, there is a tendency that resistance of exhaust gas or intake air is relatively increased during opening of the movable vane than during closing of the movable vane. Therefore, it is more effective to lower the drive force in the opening direction than the drive force in the closing direction for achieving downsizing of the actuator. 
     In addition, distance from the rotation center of the movable vane to an end edge at an outer circumferential side of the movable vane may be set to be larger than distance from the center position to an end edge at an inner circumferential side of the movable vane as the lowering device. According to this embodiment, it is possible to exert moment to the movable vane in the opening direction with force applied to the movable vane by flow of exhaust gas or intake air. Accordingly, the drive force in the opening direction to be added by the actuator to the operation input portion can be lowered as utilizing the force applied to the movable vane caused by exhaust gas or intake air as assist force against the drive force in the opening direction. 
     In one embodiment of the supercharger of the present invention, operational direction of the operation input portion of the exhaust-side movable vane mechanism and operational direction of the operation input portion of the intake-side vane drive mechanism are may be set respectively in circumferential directions of the turbine and the compressor; a relation between the operational direction of the operation input portion of the intake-side movable vane mechanism and the open-close direction of the movable vane of the intake-side movable vane mechanism may be set to be opposite to a relation between the operational direction of the operation input portion of the exhaust-side movable vane mechanism and the open-close direction of the movable vane of the exhaust-side movable vane mechanism; and the drive mechanism may include an output shaft which is rotationally driven by the actuator, an exhaust-side interlock mechanism which converts rotation of the output shaft into rotation of the operation input portion of the exhaust-side movable vane mechanism as existing between one side against the center part of the output shaft and the operation input portion of the exhaust-side movable vane mechanism, and an intake-side interlock mechanism which converts rotation of the output shaft into rotation of the operation input portion of the intake-side movable vane mechanism as existing between the other side against the center part of the output shaft and the operation input portion of the intake-side movable vane mechanism. According to this embodiment, when the output shaft is rotated by the actuator, the rotational motion is transmitted to the operation input portion of the exhaust-side movable vane mechanism and the operation input portion of the intake-side movable vane mechanism via the respective interlock mechanisms as being directed mutually opposite in the circumferential direction. Accordingly, it is possible to operate the respective movable vanes of a pair of the movable vane mechanisms in the same direction owing to the rotational motion in one direction generated by the actuator such that one movable vane mechanism is operated in the opening direction while the other movable vane mechanism is operated in the opening direction as well. 
     In addition, the operation input portion of the exhaust-side movable vane mechanism and the operation input portion of the intake-side movable vane mechanism may be located at the same side viewing from a turbine shaft; the output shaft may be arranged in parallel with the turbine shaft; and each of the exhaust-side interlock mechanism and the intake-side interlock mechanism may include a rod which is rotatably connected respectively to the output shaft and the operation input portion thereof. According to this embodiment, when the output shaft of the actuator is rotated in one direction, the operation input portion of one movable vane mechanism is pushed out via the rod and the operation input portion of the other movable vane mechanism is pulled in via the rod. As a result, the operation input portions of both of the movable vane mechanisms are operated being mutually opposite in the circumferential direction, so that the movable vanes are operated in the same direction. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a partially broken side view of a turbine side of a turbocharger according to an embodiment of the present invention. 
         FIG. 2  is a partially broken side view of a compressor side of the turbocharger according to the embodiment of the present invention. 
         FIG. 3  is a partial sectional view taken along an axis line direction of the turbocharger according to the embodiment of the present invention. 
         FIG. 4  is a view showing a structure from an operation lever to an arm in a movable vane mechanism at the turbine side. 
         FIG. 5  is a view showing a structure around movable vanes in the movable vane mechanism at the turbine side. 
         FIG. 6  is a view showing a structure from an operation lever to an arm in a movable vane mechanism at the compressor side. 
         FIG. 7  is a view showing a structure around movable vanes in the movable vane mechanism at the compressor side. 
         FIG. 8  is an enlarged view of a part of movable vanes. 
         FIG. 9  is an explanatory view of moment when driving the movable vanes in the opening direction. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIGS. 1 to 3  show a turbocharger as a variable capacity supercharger according to an embodiment of the present invention. A turbocharger  1  is provided with a turbine  2  and a compressor  3 . The turbine  2  includes a turbine housing  4  and a turbine wheel  5  arranged in the turbine housing  4 . The turbine housing  4  is placed at some midpoint of an exhaust path of an internal combustion engine (hereinafter, referred to as engine, not shown). The turbine housing  4  is provided with an exhaust gas inlet port  4   a  to be connected to the upstream side of the exhaust path (i.e., the exhaust port side of the engine) at an outer circumference thereof and an exhaust gas outlet port  4   b  to be connected to the downstream side of the exhaust path at the center part thereof. Here, the turbine housing  4  and a structure of surroundings thereof are not shown in  FIG. 3  for simplicity. A turbine shaft  6  is formed coaxially with the turbine wheel  5  and is supported rotatably by a bearing portion  8  in a bearing housing  7 . 
     Meanwhile, the compressor  3  includes a compressor housing  10  and a compressor wheel  11  arranged in the compressor housing  10 . The compressor housing  10  is placed at some midpoint of an intake path of the engine. The compressor housing  10  is provided with an intake air inlet port  10   a  to be connected to the upstream side of the intake path of the engine at the center part thereof and an intake air outlet port  10   b  to be connected to the downstream side of the intake path at an outer circumference thereof. The compressor wheel  11  is attached at a distal end part of the turbine shaft  6  as being integrally rotatable. 
     A movable vane mechanism is further provided respectively to the turbine  2  and the compressor  3  as not shown in  FIGS. 1 and 2  for simplicity. Further, a drive mechanism  40  is provided to the turbocharger  1  to drive the movable vane mechanisms. 
       FIGS. 4 and 5  show details of the movable vane mechanism  20  at the turbine  2  side (hereinafter, referred to as the exhaust-side movable vane mechanism). Both of  FIGS. 4 and 5  shows a state of viewing the turbine  2  in the same direction as  FIG. 1  (i.e., corresponds to the direction of arrow I of  FIG. 3 ). 
     The exhaust-side movable vane mechanism  20  includes a base plate  21  located behind the turbine wheel  5 , that is, at the side of the bearing housing  7 , a number of movable vanes  23  attached on a front face of the base plate  21  as being rotatable respectively having a pin  22  as an axis, and a vane operation mechanism  24  located at a rear face side of the base plate  21 . The movable vanes  23  are wing-shaped components (see  FIG. 8 ) to direct exhaust gas flow so that exhaust gas flowing into the turbine housing  4  is guided to the outer circumference of the turbine wheel  5 . That is, clearances between the movable vanes  23  constitute a flow path of exhaust gas toward the turbine wheel  5 . Each movable vane  23  is attached to one end part of each pin  22  as being integrally rotatable. Intervals of the pins  22  in the circumferential direction are equaled. The movable vanes  23  are rotated so as to open and close the exhaust path therebetween by rotating the movable vanes  23  having the respective pins  22  as axes, so that cross-sectional area of the exhaust path is varied. Here, a state that the exhaust path between the movable vanes  23  is opened is shown in  FIG. 5  with solid lines. A state of being rotated until the exhaust path therebetween is approximately closed is shown with imaginary lines for some of the movable vanes  23 . 
     The vane operation mechanism  24  includes a drive ring  25 , a number of vane arms  26  located at an inner side of the drive ring  25 , a drive arm  27  located between a pair of the vane arms  26 , and an operation lever  29  connected to the drive arm  27  via a pin  28  as being integrally rotatable. The operation lever  29  is an operation input portion in the vane operation mechanism  24 . The drive ring  25  is supported by an appropriate number of rollers  21   a  attached to the base plate  21  as being rotatable about an axis line of the turbine shaft  6  (see  FIG. 3 ). The number of the vane arms  26  is the same as that of the movable vanes  23 . Each vane arm  26  is connected to the other end part of each pin  22  protruded as piercing the base plate  21  to the rear face side as being integrally rotatable. Accordingly, the movable vane  23  and the vane arm  26  integrally rotate having the pin  22  as an axis. 
     A number of vane-arm groove portions  25   a  and a drive-arm groove portion  25   b  which is located between a pair of the groove portions  25   a  are arranged at the inner circumference of the drive ring  25 . The number of the vane-arm groove portions  25   a  is the same as that of the vane arms  26 . The vane-arm groove portions  25   a  are arranged at equal intervals in the circumferential direction. A distal end portion  26   a  of each vane arm  26  is fitted to each vane-arm groove portion  25   a . Meanwhile, a distal end portion  27   a  of the drive arm  27  is fitted to the drive-arm groove portion  25   b . Accordingly, when the operation lever  29  is rotationally operated in the direction of arrow Ct of  FIG. 4  (i.e., the clockwise direction), the rotation is transmitted to the drive ring  25  via the drive arm  25  from the pin  28  to rotate the drive ring  25  in the same direction. As being interlocked therewith, each vane arm  26  is rotated about each pin  22  in the clockwise direction in  FIGS. 4 and 5 . Accordingly, each movable vane  23  is also rotated about each pin  22  in the clockwise direction, so that cross-sectional area of the exhaust path between the movable vanes  23  is decreased. On the contrary, when the operation lever  29  is rotationally operated in the direction of arrow Ot of  FIG. 4  (i.e., the counterclockwise direction), the drive ring  25  is rotated in the opposite direction to the above. In accordance therewith, each movable vane  23  is rotated about each pin  22  in the counterclockwise direction. With the above, cross-sectional area of the exhaust path between the movable vanes  23  is increased. That is, the movable vanes  23  are opened when the drive ring  25  is rotated in the same direction as the rotation direction R of the turbine shaft  6  and the movable vanes  23  are closed when the drive ring  25  is rotated in the opposite direction to the rotation direction R of the turbine shaft  6 . 
       FIGS. 6 and 7  show details of the movable vane mechanism  30  at the compressor  3  side (hereinafter, referred to as the intake-side movable vane mechanism). Both of  FIGS. 6 and 7  shows a state of viewing the compressor  3  in the same direction as  FIG. 2  (i.e., corresponds to the direction of arrow II of  FIG. 3 ). 
     The intake-side movable vane mechanism  30  includes a base plate  31  located behind the compressor wheel  11 , that is, at the side of the bearing housing  7 , a number of movable vanes  33  attached on a front face of the base plate  31  as being rotatable respectively having a pin  32  as an axis, and a vane operation mechanism  34  arranged at a rear face side of the base plate  31 . The movable vanes  33  are wing-shaped components to direct intake air flow so that intake air flowing to the center part of the compressor wheel  11  is guided to the outer circumference of the compressor wheel  11 . That is, clearances between the movable vanes  33  constitute a flow path of intake air to be delivered from the compressor wheel  11 . Each movable vane  33  is attached to one end part of each pin  32  as being integrally rotatable. Intervals of the pins  32  in the circumferential direction are equaled. The movable vanes  33  are rotated so as to open and close the intake path therebetween by rotating the movable vanes  33  having the respective pins  32  as axes, so that cross-sectional area of the intake path is varied. Here, a state that the intake path between the movable vanes  33  is opened is shown in  FIG. 7  with solid lines. A state of being rotated until the intake path therebetween is approximately closed is shown with imaginary lines for some of the movable vanes  33 . 
     The vane operation mechanism  34  includes a drive ring  35 , a number of vane arms  36  located at an inner side of the drive ring  35 , a drive arm  37  located between a pair of the vane arms  36 , and an operation lever  39  connected to the drive arm  37  via a pin  38  as being integrally rotatable. The operation lever  39  is an operation input portion in the vane operation mechanism  34 . The operation lever  39  is located at the same side as the operation lever  29  of the exhaust-side movable vane mechanism  20  viewing from the turbine shaft  6  (e.g., the right side of the turbine shaft in  FIG. 1 ). The driver ring  35  is supported by an appropriate number of rollers  31   a  attached to the base plate  31  as being rotatable about the axis line of the turbine shaft  6  (see  FIG. 3 ). The number of the vane arms  36  is the same as that of the movable vanes  33 . Each vane arm  36  is connected to the other end part of each pin  32  protruded as piercing the base plate  31  to the rear face side as being integrally rotatable. Accordingly, the movable vane  33  and the vane arm  36  integrally rotate having the pin  32  as an axis. 
     A number of vane-arm groove portions  35   a  and a drive-arm groove portion  35   b  which is located between a pair of the groove portions  35   a  are arranged at the inner circumference of the drive ring  35 . The number of the vane-arm groove portions  35   a  is the same as that of the vane arms  36 . The vane-arm groove portions  35   a  are arranged at equal intervals in the circumferential direction. A distal end portion  36   a  of each vane arm  36  is fitted to each vane-arm groove portion  35   a . Meanwhile, a distal end portion  37   a  of the drive arm  37  is fitted to the drive-arm groove portion  35   b . Accordingly, when the operation lever  39  is rotationally operated in the direction of arrow Cc of  FIG. 6  (i.e., the clockwise direction), the rotation is transmitted to the drive ring  35  via the drive arm  35  from the pin  38  to rotate the drive ring  35  in the same direction. As being interlocked therewith, each vane arm  36  is rotated about each pin  32  in the clockwise direction in FIGS.  6  and  7 . Accordingly, each movable vane  33  is also rotated about each pin  32  in the clockwise direction, so that cross-sectional area of the intake path between the movable vanes  33  is decreased. On the contrary, when the operation lever  39  is rotationally operated in the arrow Oc of  FIG. 6  (i.e., the counterclockwise direction), the drive ring  35  is rotated in the opposite direction to the above. In accordance therewith, each movable vane  33  is rotated about each pin  32  in the counterclockwise direction. With the above, cross-sectional area of the intake path between the movable vanes  33  are increased. That is, the movable vanes  33  are closed when the drive ring  35  is rotated in the same direction as the rotating direction R of the turbine shaft  6  and the movable vanes  33  are opened when the drive ring  25  is rotated in the opposite direction to the rotation direction R of the turbine shaft  6 . The relation between the operational direction of the operation lever  39  and the open-close direction of the movable vanes  33  is opposite to the relation between the operational direction of the operation lever  29  and the open-close direction of the movable vanes  23  in the exhaust-side movable vane mechanism  20 . 
     As shown in  FIG. 8 , attaching positions of the pins  22  against the movable vanes  23  of the exhaust-side movable vane mechanism  20  are disproportioned respectively to the side of a rear edge (i.e., an end edge at the inner circumferential side)  23   b  of the movable vane  23  from the center position of the movable vane  23  in the longitudinal direction. That is, the attaching positions of the pins  22  are determined so that a pivot ratio Lb/La is to be larger than 0.5 as indicated by equation (1) in the following. Here, La denotes the total length of the movable vane  23  and Lb denotes the distance from the pin  22  to a front edge (an end edge at the outer circumferential side)  23   a  of the movable vane  23 . Since the movable vanes  23  are to change the flow direction of exhaust gas from the circumferential direction of the turbine wheel  5  toward the center side in the radial direction, a front face  23   c  side to which exhaust gas flow collides receives larger force from exhaust gas than a back face  23   d  side. Receiving force at an area between the front edge  23   a  of the movable vane  23  and the pin  22  exerts moment to the movable vane  23  in the opening direction and receiving force at an area between the pin  22  and the rear edge  23   b  exerts moment to the movable vane  23  in the closing direction. The magnitude relation of the moment therebetween depends on the respective distances from the pin  22  to the front edge  23   a  and the rear edge  23   b . Accordingly, when the pivot ratio is set as described above, moment Mo is exerted to the movable vane  23  in the opening direction. That is, in the exhaust-side movable vane mechanism  20 , drive force in the opening direction to be input to the operation lever  29  for operating the movable vanes  23  in the opening direction is lowered than drive force in the closing direction to be input to the operation lever  29  for operating the movable vanes  23  in the closing direction. 
       Lb/La&gt;0.5  (1)
 
     Further, attaching positions of the pins  32  of the movable vanes  33  of the intake-side movable vane mechanism  30  are set as being similar to  FIG. 8 . That is, the pivot ratio is as indicated by equation (1) in the above as replacing the movable vanes  23  of  FIG. 8  with the movable vanes  33 . Accordingly, moment is also exerted to the movable vanes  33  in the opening direction about the respective pins  32 . Therefore, in the intake-side movable vane mechanism  30  as well, drive force in the opening direction to be input to the operation lever  39  for operating the movable vanes  33  in the opening direction is lowered than drive force in the closing direction to be input to the operation lever  39  for operating the movable vanes  33  in the closing direction. 
     As shown in  FIGS. 1 and 2 , the drive mechanism  40  includes a single electric motor  41 . The electric motor  41  is an actuator to function as a drive source respectively for the movable vanes  23 ,  33  as being used commonly by the movable vane mechanisms  20 ,  30 . Rotation of the electric motor  41  is obtained from an output shaft  43  as being reduced in speed by a speed reduction mechanism  42 . The output shaft  43  is arranged in parallel with the turbine shaft  6  and is rotationally driven by the electric motor  41  about the center part  43   a  thereof within a predetermined angle range. The drive mechanism  40  is provided with a link mechanism  45  to connect the output shaft  43  to the respective operation levers  29 ,  30  of the movable vane mechanisms  20 ,  30 . 
     The link mechanism  45  includes a first rod  47  rotatably connected at one end side against the center part  43   a  of the output shaft  43  via a pin  46  and a second rod  49  rotatably connected to a position at the other side against the pin  46  as sandwiching the center part  43   a  via a pin  48 . As shown in  FIG. 1 , a distal end part of the first rod  47  is rotatably connected to the operation lever  29  of the exhaust-side movable vane mechanism  20  via a pin  50 . Meanwhile, as shown in  FIG. 2 , a distal end part of the second rod  49  is rotatably connected to the operation lever  39  of the intake-side movable vane mechanism  30  via a pin  51 . In the link mechanism  45 , the pin  46 , the first rod  47  and the pin  50  function as an exhaust-side interlock mechanism, and then, the pin  48 , the second rod  48  and the pin  51  function as an intake-side interlock mechanism. 
     Next, driving of the movable vane mechanisms  20 ,  30  by the drive mechanism  40  will be described. When the output shaft  43  is rotationally operated by the motor  41  of the drive mechanism  40  in the direction of arrow O of  FIG. 2 , the first link  47  is lifted and the operation lever  29  is rotationally driven in the rotation direction R of the turbine shaft  6  as being rotated in the rotation direction R of the turbine shaft  6 . As is obvious from  FIGS. 4 and 5 , when the operation lever  29  is driven in the rotation direction R, the movable vanes  23  are rotated in the direction to open the flow path therebetween (i.e., the direction of arrow Ot). Further, the second link  49  is depressed and the operation lever  39  is rotated in the opposite direction to the rotation direction R of the turbine shaft  6 . As is obvious from  FIGS. 6 and 7 , when the operation lever  39  is rotated in the opposite direction to the rotation direction R of the turbine shaft  6 , the movable vanes  33  are rotated in the direction to open the flow path therebetween (i.e., the direction of arrow Oc). 
     On the contrary, when the output shaft  43  is rotatably driven by the motor  41  of the drive mechanism  40  in the direction of arrow C of  FIG. 2 , the first link  47  is depressed and the operation lever  29  is rotationally driven in the opposite direction to the rotation direction R of the turbine shaft  6  as being rotated in the opposite direction to the rotation direction R of the turbine shaft  6 . As is obvious from  FIGS. 4 and 5 , when the operation lever  29  is driven in the opposite direction to the rotation direction R, the movable vanes  23  are rotated in the direction to close the flow path therebetween (i.e., the direction of arrow Ct). Further, the second link  49  is lifted and the operation lever  39  is rotated in the rotation direction R of the turbine shaft  6 . As is obvious from  FIGS. 6 and 7 , when the operation lever  39  is rotated in the rotation direction R of the turbine shaft  6 , the movable vanes  33  are rotated in the direction to close the flow path therebetween (i.e., the direction of arrow Cc). 
     As described above, according to the turbocharger  1  of the present embodiment, the movable vanes  23  at the turbine  2  side and the movable vanes  33  at the compressor  3  side can be integrally driven in the opening direction or closing direction by the single electric motor  41 . Accordingly, it is possible to reduce in size and weight compared to a case that a dedicated actuator is arranged respectively to the turbine side and the compressor side. Therefore, it is possible to relieve space restriction for accommodating the turbocharger  1  in an engine room of a vehicle. Accordingly, it is possible to achieve vehicle lightening and cost reduction. 
     Here, opening control of the movable vanes  23 ,  33  may be the same as that of a known variable capacity turbocharger. For example, the operation of the electric motor  41  may be controlled to keep both of the movable vanes  23 ,  33  closed to the maximum while an engine is operated at idling and to gradually open the movable vanes  23 ,  33  in accordance with increase of the engine revolution speed. Further, when the engine revolution speed decreases, both of the movable vanes  23 ,  33  may be driven to the closing side. It is also possible to perform feedback control on the opening of the movable vanes  23 ,  33  to obtain a target supercharging pressure which is set in accordance with the revolution speed and load of the engine. 
     In the turbocharger  1  of the present embodiment, since both of the movable vanes  23 ,  33  are driven by the common electric motor  41 , the opening of the movable vanes  33  at the compressor  3  side are unambiguously determined as well when the opening of the movable vanes  23  at the turbine  2  side is determined. Therefore, provided that a control program for the movable vanes at either the turbine side or the compressor side exists, there is an advantage that the both openings of the movable turbines  23 ,  33  can be appropriately controlled by utilizing the program. Here, it is assumed that a program to appropriately control the opening of the movable vanes  23  in accordance with the revolution speed and load of an engine exists for a turbine having the same specifications, for example. In this case, it is possible to appropriately control the opening of the movable vanes  33  at the compressor  3  side as well only by utilizing the control program for the movable vanes  23  at the turbine  2  side by previously obtaining data of the opening of the movable vanes  33  to maximize the compressor efficiency in accordance with the opening (i.e., the position) of the movable vanes  23  while operating the movable vanes  23  corresponding to the program and by adjusting length dimensions, attaching positions and the like of the output shaft  43 , the second rod  49  and the operation lever  39  so that the movable vanes  33  are operated corresponding to the obtained data. In this regard, in the case that the movable vanes  23 ,  33  are driven respectively by a separate actuator, the opening of the movable vanes  33  is required to be controlled so that the compressor efficiency is maximized after detecting state quantity such as supercharging pressure and air-flow quantity appearing as control effects while performing feedback control of the opening of the movable vanes  23  at the turbine  2  side, for example. Accordingly, the control becomes complicated with increased control parameters and the supercharging performance is impaired when response difference occurs between both controls. On the contrary, the present embodiment can be sufficiently controlled being similar to the control of a turbocharger which has movable vanes only at the turbine side or the compressor side. Accordingly, the control becomes uncomplicated, and there is not a fear of supercharging performance decrease due to delay in response. 
     Further, in the turbocharger  1  of the present embodiment, assist force in the opening direction is exerted to the movable vanes  23 ,  33  as utilizing flow of exhaust gas or intake air for operating the movable vanes  23 ,  33  in the opening direction by setting the pivot ratio of the movable vanes  23 ,  33  as described above, so that drive force to be input to the operation lever  29 ,  39  is lowered. Accordingly, it is possible to lower the output torque of the electric motor  41  required for driving the movable vanes  23 ,  33  in the opening direction. That is, as shown in  FIG. 9 , assist forces FAvn, FAvgc corresponding to the forces received by the movable vanes  23 ,  33  from exhaust gas are exerted to the pins  46 ,  48  which are located at connection points between the output shaft  43  and the respective rods  47 ,  49  in the direction to open the movable vanes  23 ,  33  (i.e., the direction of arrow A). Meanwhile, drive resistances FBvn, FBvgc are exerted in the direction to close the movable vanes  23 ,  33  (i.e., the direction of arrow B). Drive torque (i.e., moment) Tm to be generated about the center part  43   a  of the output shaft  43  for opening the movable vanes  23 ,  33  is expressed by equation (2) in the following. Here, Lvn and Lvgc denote respective distances from the center  43   a  of the output shaft  43  to the respective pin  46 ,  48  being the connection points of the rods  47 ,  49 . 
       Tm=FBvn·Lvn+FBvgc·Lvgc−(FAvn·Lvn+FAvgc·Lvgc)  (2)
 
     The moment generated by setting the pivot ratio of the movable vanes  23 ,  33  as described above is expressed in parentheses of equation (2) and the direction thereof corresponds to the rotation direction of the output shaft  43  (i.e., the direction of the drive torque Tm) to drive the movable vane  23 ,  33  in the opening direction. Accordingly, output torque of the electric motor  41  can be sufficient as being less compared to a case that moment in the same direction cannot be obtained or a case that moment in the opposite direction is generated. In this manner, even with the structure to drive both of the movable vanes  23  at the turbine  2  side and the movable vanes  33  at the compressor  3  side by the single electric motor  41 , it is possible to reduce in size and weight of the electric motor  41  as reducing rated torque required for the electric motor  41 . 
     The present invention is not limited to the above-described embodiments, and may be embodied in various modes. In the above embodiment, the pivot ratios of the movable vanes  23 ,  33  are set as expressed by equation (1) as a device to lower the drive force of the operation lever  29 ,  39  in the opening direction compared to the drive force in the closing direction. However, it is also possible to lower the output torque of the electric motor  41  when the pivot ratio of only one of the movable vane mechanisms is set as expressed by equation (1) compared to a case that the pivot ratios of the both movable vane mechanisms do not satisfy equation (1). Further, not limited to the pivot ratio, it is possible to lower drive force required for the actuator such as an electric motor by applying force to the movable vanes in the opening direction with a device such as a spring. Further, when it is possible to dispose an actuator having sufficient performance even if the drive force in the opening direction is set to be the same magnitude of the drive force in the closing direction or larger, the device to lower the drive force in the opening direction compared to the drive force in the closing direction can be omitted. 
     The above structure of the exhaust-side movable vane mechanism  20  and the intake-side movable vane mechanism  30  is an example and the movable vane mechanisms can be appropriately modified as long as being structured to vary cross-sectional area of flow path of exhaust gas or intake air owing to open-close operation of movable vanes. Not limited to an electric motor, the actuator can be appropriately modified as long as being an apparatus to generate drive force by utilizing fluid pressure or electric power. Not limited to the examples shown in the drawings, the arrangement of the actuator and the output shaft thereof and the structure of the exhaust-side interlock mechanism and the intake-side interlock mechanism can be modified such that operation of a liner motion actuator is transmitted to an operation input portion of a movable vane mechanism by utilizing various mechanical elements such as a gear, a lever and a link, for example.