Abstract:
The invention is aimed at making a space necessary for installing an adjusting mechanism for a diffuser small to thereby miniaturize a turbocompressor as well as a refrigerating machine where this turbocompressor is a constituent element.  
     A compressor incorporating a diffuser  34  adopts an adjusting mechanism comprising; a diffuser ring  37  forming one wall  34   a,  arranged so as to be a concentric circle with the surroundings of a second stage impeller  17   b  and supported on a casing  25,  and which can be rotated in the circumferential direction and which can be moved in an axial direction of the second stage impeller  17   b,  with a groove  37   a  formed on an outer peripheral face at an incline to the axial direction of the second stage impeller  17   b;  a protrusion  40  provided on the casing  25  and fitted into the groove  37   a;  a shaft  38  axially supported on the diffuser ring  37;  and a drive section  39  for driving the shaft  38  in a lengthwise direction.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a diffuser applicable to a turbocompressor such as a radial compressor and the like, a turbocompressor incorporating this diffuser, and a refrigerating machine with this turbocompressor as a constituent element.  
           [0003]    2. Description of the Related Art  
           [0004]    In a turbocompressor such as a radial compressor, there is provided a diffuser for reducing the velocity of a fluid to convert kinetic energy held by the fluid into internal energy. One example of a turbocompressor provided with a diffuser is shown in FIG. 11. In the figure, reference symbol  1  denotes a casing,  2  a main shaft,  3  an impeller,  4  a diffuser section,  5  a return bend,  7  a guide vane, and  8  an inlet port. In the diffuser section  4  there is provided in combination; a diffuser  9  which has no vanes, and a vane diffuser  10  having a plurality of vanes  10   a  arranged spaced at equal intervals on an outer peripheral section of the diffuser  9 .  
           [0005]    A fluid to be compressed by the turbocompressor is sucked in from the inlet port  8  as shown by the white arrow in the figure, and is then sequentially passed through the impeller  3 , the diffuser section  4 , the return bend  5 , and the guide vanes  7 , and increased in pressure, and then introduced to the next stage inlet.  
           [0006]    However, in the conventional turbocompressor, the inlet angle of the fluid to the diffuser section  4  is changed when the intake flow rate of fluid for the impeller  3  is changed. Therefore, for example even if an optimum diffuser effect is obtained where at a certain intake flow rate the flow direction of the discharged fluid from the impeller  3  coincides with the set direction of the vanes  10   a,  there is the case where if the intake flow rate is changed, then both of these directions no longer coincide so that a sufficient diffuser effect is not obtained.  
           [0007]    Therefore, in the aforementioned turbocompressor, one wall  9   a  constituting the diffuser  9  is made so as to be able to approach or separate from the other wall  9   b  to enable the effectiveness of the diffuser  9  to be adjusted. Hence even though the intake flow rate of fluid to the later stage vane diffuser  10  with which this is combined changes, an optimum diffuser effect is obtained.  
           [0008]    An adjusting mechanism for the diffuser  9  is shown in FIG. 12. In the figure, reference symbol  11  denotes a diffuser ring,  12  a drive ring,  13  a connecting shaft, and  14  a drive ring lever. As for the diffuser ring  11 , one side face constitutes the wall  9   a , and this wall  9   a  is exposed to the passage and is built in to the casing  1 . On the outside of the casing  1  is arranged a drive ring  12  made concentric with the center of the diffuser ring  11 , and both of these are connected by a connecting shaft  13  passing through an aperture  1   a  through the casing  1 . An inclined cam groove  12   a  is formed in the drive ring  12 , and a bearing  15  is engaged in this inclined cam groove  12   a . One end of the same bearing is connected to an end portion of the connecting shaft  13 .  
           [0009]    Therefore, when the drive ring  12  is turned in one direction via the drive ring lever  14 , the bearing  15  is displaced in the axial direction so that the connecting shaft  13  is slid axially along the aperture  1   a.  As a result, the diffuser ring  11  is pushed out and moves out to the passage side. Moreover, when the drive ring  12  is rotated in the other direction via the drive ring lever  14 , the diffuser ring  11  returns to the original position.  
           [0010]    In the aforementioned turbocompressor, there is the problem that since the adjusting mechanism for the diffuser is on a large scale, a large installation space is necessary. Moreover since there are many sliding parts, a large drive force is required. Furthermore high accuracy is necessary in boring the holes in the casing side, and in machining the two rings.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention takes into consideration the above situation with: an object of making the space necessary for installing the adjusting mechanism for the diffuser small to thereby miniaturize the turbocompressor as well as a refrigerating machine where this turbocompressor is a constituent element; an object of being able to drive the adjusting mechanism of the diffuser with a small drive force to enable energy saving of the turbocompressor and a refrigerating machine incorporating this turbocompressor; and an object of simplifying the construction of the adjusting mechanism of the diffuser to decrease time and labor in machining and thus reduce manufacturing costs.  
           [0012]    As a means for solving the abovementioned problems, a turbocompressor and refrigerating machine of the following construction is adopted. That is to say, a turbocompressor according to a first aspect of the invention is one with a diffuser provided around an impeller periphery with one wall which can approach or separate from another wall and spaced apart therefrom with a passage for fluid therebetween, and comprises:  
           [0013]    a diffuser ring forming the one wall, arranged so as to be a concentric circle with the surroundings of the impeller and supported on the casing, and which can be rotated in the circumferential direction and which can be moved in an axial direction of the impeller, with a groove formed on an outer peripheral face at an incline to the axial direction of the impeller, a protrusion provided on the casing and fitted into the groove, a shaft axially supported on the diffuser ring, and a drive section for driving the shaft in a lengthwise direction.  
           [0014]    In this turbocompressor, when the shaft is driven in the lengthwise direction thereof, the linear motion of the shaft is converted to rotary motion of the diffuser ring, so that the diffuser ring rotates in the circumferential direction. At this time, the protrusion fitted into the groove guides the diffuser ring along the groove. However since the groove is formed at an incline to the axial direction, the diffuser ring also moves in the axial direction in addition to rotating in the circumferential direction. Consequently, when the shaft is moved in one direction, the diffuser ring is pushed in to the passage side while rotating in the circumferential direction, and when moved in the other direction, this moves in reverse returning to the original position.  
           [0015]    As a result, the number of ring shape members can be reduced compared to heretofore, and the construction simplified. Therefore there is the effect that, the mechanism itself can be made compact, and due to the decrease in sliding parts, energy losses can be reduced, and due to a reduction in the number of parts, time and labor in processing can be minimized. Moreover, since the diffuser ring is rotated by converting the linear motion of the shaft into rotary motion of the diffuser ring, the diffuser ring can be rotated using a drive section (for example a hydraulic cylinder) which performs simple linear motion. Also due to this, an affect similar to the above can be expected.  
           [0016]    The turbocompressor according to a second aspect is characterized in that in the turbocompressor according to the first aspect, there is provided a vane diffuser having a plurality of vanes separated in the circumferential direction, further outside than the diffuser.  
           [0017]    In this turbocompressor, since the effect of the diffuser can be adjusted, if a vane diffuser is combined on the outside thereof, then even if the fluid intake flow rate is changed, an optimum diffuser affect is obtained.  
           [0018]    A turbocompressor according to a third aspect of the invention is one with a diffuser provided around an impeller periphery with one wall which can approach or separate from another wall and spaced apart therefrom with a passage for fluid therebetween, and comprises:  
           [0019]    a diffuser ring forming the one wall, arranged so as to be a concentric circle with the surroundings of the impeller and supported on the casing, and which can be moved in an axial direction of the impeller, a bar with an approximate center thereof supported on the casing and able to swing in an axial direction of the impeller, with one end connected to the diffuser ring, and a drive section for swinging an other end of the bar in the axial direction.  
           [0020]    In this turbocompressor, when the other end of the bar is swung, then according to the theory of levers, the one end of the bar swings in the opposite direction so that the diffuser ring connected to this moves in the axial direction. Consequently, when the other end of the bar is swung in one direction, the diffuser ring is pushed in to the passage side. Moreover, when swung in the other direction, this moves in reverse returning to the original position.  
           [0021]    A turbocompressor according to a fourth aspect of the invention is one with a diffuser provided around an impeller periphery with one wall which can approach or separate from another wall and spaced apart therefrom with a passage for fluid therebetween, and comprises:  
           [0022]    a diffuser ring forming the one wall, arranged so as to be a concentric circle with the surroundings of the impeller and supported on the casing, and which can be moved in an axial direction of the impeller, a shaft supported on the casing and movable in the axial direction, a connecting member for connecting one end of the shaft to the diffuser ring, and a drive section for moving the shaft in the axial direction.  
           [0023]    In this turbocompressor, when the shaft is moved in the axial direction of the impeller, this movement is transmitted to the diffuser ring via the connecting member so that the diffuser ring moves in the axial direction. Therefore, when the shaft is moved in one direction, the diffuser ring is pushed in to the passage side. Moreover, when moved in the other direction, this moves in reverse returning to the original position.  
           [0024]    A turbocompressor according to a fifth aspect of the invention is one with a diffuser provided around an impeller periphery with one wall which can approach or separate from another wall and spaced apart therefrom with a passage for fluid therebetween, and comprises:  
           [0025]    a diffuser ring forming the one wall, arranged so as to be a concentric circle with the surroundings of the impeller and supported on the casing, and which can be rotated in the circumferential direction and which can be moved in an axial direction of the impeller, a shaft arranged in a radial direction of the diffuser ring and supported on the casing and centered on an axis in the radial direction, an eccentric shaft section provided eccentrically on one end of the shaft and rotatably coupled to the diffuser ring, and a drive section for rotating the shaft.  
           [0026]    In this turbocompressor, when the shaft is rotated, the eccentric shaft section is eccentrically rotated and the movement thereof is transmitted to the diffuser ring so that the diffuser ring also moves in the axial direction in addition to rotating in the circumferential direction. Consequently, when the shaft is rotated in one direction, the diffuser ring is pushed in to the passage side while rotating in the circumferential direction, and when rotated in the other direction, this moves in reverse returning to the original position.  
           [0027]    A turbocompressor according to a sixth aspect of the invention is one with a diffuser provided around an impeller periphery with one wall which can approach or separate from another wall and spaced apart therefrom with a passage for fluid therebetween, and comprises:  
           [0028]    a diffuser ring forming the one wall, arranged so as to be a concentric circle with the surroundings of the impeller and supported on the casing, and which can only be moved in an axial direction of the impeller, with a first helical gear section formed on an outer circumferential surface, a shaft supported on the casing and able to rotate about an axis parallel to an axis of the impeller, an arm member secured to one end of the shaft, with a second helical gear section for meshing with the first helical gear section, formed on a tip end, and a drive section for rotating the shaft.  
           [0029]    In this turbocompressor, when the shaft is rotated, the arm member swings, and the swinging is transmitted to the diffuser ring via the second helical gear section and the first helical gear section. Here since the diffuser ring can only move in the axial direction of the impeller, the force transmitted via the first and second helical gear sections becomes a component only in the axial direction of the impeller. Consequently, when the shaft is rotated in one direction, the diffuser ring is moved in the axial direction and pushed in to the passage side. Moreover, when rotated in the other direction, this moves in reverse returning to the original position.  
           [0030]    A refrigerating machine according to a seventh aspect of the invention, is characterized in comprising: a turbocompressor according to any one of the first, second, third, fourth, fifth and sixth aspects of the invention; a condenser for condensing and liquefying a gaseous refrigerant compressed by the turbocompressor; a metering valve for reducing the pressure of the refrigerant liquefied by the condenser; and an evaporator for performing heat exchange between refrigerant reduced in pressure by the metering valve and a substance to be cooled, to cool the substance to be cooled, and evaporate and gasify the refrigerant.  
           [0031]    With this refrigerating machine, in the turbocompressor the aforementioned effect is obtained. Therefore for the refrigerating machine also, the equipment is made compact, energy saved and cost reduced. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]    [0032]FIG. 1 is a diagram showing a first embodiment according to the present invention, being a perspective view of a refrigerating machine which uses a turbocompressor.  
         [0033]    [0033]FIG. 2 is a schematic diagram showing a system structure of the refrigerating machine shown in FIG. 1.  
         [0034]    [0034]FIG. 3 is a cross-section view of a compressor.  
         [0035]    [0035]FIG. 4 is a cross-section view showing an adjusting mechanism of a diffuser.  
         [0036]    [0036]FIG. 5 is a view on line V-V in FIG. 4.  
         [0037]    [0037]FIG. 6 is a side view and plan view showing the shape of a groove formed in a diffuser ring.  
         [0038]    [0038]FIG. 7 is a view showing a second embodiment according to the present invention, being a cross-section view showing an adjusting mechanism of a diffuser.  
         [0039]    [0039]FIG. 8 is a view showing a third embodiment according to the present invention, being a cross-section view showing an adjusting mechanism of a diffuser.  
         [0040]    [0040]FIG. 9 is a view showing a fourth embodiment according to the present invention, being a cross-section view showing an adjusting mechanism of a diffuser.  
         [0041]    [0041]FIG. 10 is a view showing a fifth embodiment according to the present invention, being a cross-section view showing an adjusting mechanism of a diffuser.  
         [0042]    [0042]FIG. 11 is a cross-section view showing an example of a conventional compressor.  
         [0043]    [0043]FIG. 12 is a cross-section view showing an adjusting mechanism of a diffuser in the conventional compressor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0044]    A first embodiment of a turbocompressor and a refrigerating machine according to the present invention as shown in FIG. 1 through FIG. 6, will now be described.  
         [0045]    The construction of the refrigerating machine according to the first embodiment is shown in FIG. 1 and FIG. 2. The refrigerating machine shown in the figures incorporates: an evaporator  16  for performing heat exchange between a refrigerant and chilled water for cooling the chilled water and evaporating and gasifying the refrigerant, a compressor  17  for compressing the refrigerant gasified in the evaporator  16 , a condenser  18  for performing heat exchange between the refrigerant compressed in the compressor  17  and a cooling water and condensing and liquefying the refrigerant, a metering valve  19  for reducing the pressure of the refrigerant liquefied in the condenser  18 , an intercooler  20  for temporarily accumulating and cooling the refrigerant liquefied in the condenser  18 , and an oil cooler  21  for cooling lubricant for the compressor  17  using a part of the refrigerant cooled in the condenser  18 . Furthermore, a motor  22  is connected to the compressor  17  for driving this.  
         [0046]    The evaporator  16 , the compressor  17 , the condenser  18 , the metering valve  19  and the intercooler  20  are connected together by a primary line to make up a closed system in which the refrigerant is circulated.  
         [0047]    For the compressor  17 , a two stage turbocompressor is adopted. Gaseous refrigerant is compressed by a first stage impeller  17   a,  and this refrigerant is introduced to a second stage impeller  17   b  and further compressed and then delivered to the condenser  18 .  
         [0048]    The condenser  18  comprises a main condenser  18   a  and an auxiliary condenser  18   b  referred to as a subcooler. The refrigerant is introduced in sequence from the main condenser  18   a  to the subcooler  18   b , however in the main condenser  18   a , a part of the cooled refrigerant is introduced to the oil cooler  21  without passing through the subcooler  18   b , to cool the lubricating oil. Furthermore, separate to this, in the main condenser  18   a , a part of the cooled refrigerant is introduced to inside the casing of the motor  22  without passing through the subcooler  18   b , to cool the stator and coil (omitted from the figure).  
         [0049]    Metering valves  19  are respectively installed between the condenser  18  and the intercooler  20 , and between the intercooler  20  and the evaporator  16 , so that the refrigerant liquefied in the condenser  18  is pressure reduced in stages.  
         [0050]    The construction of the intercooler  20  is equivalent to a hollow container, and the refrigerant which is cooled in the condenser  18  and the subcooler  18   b , and pressure reduced in the metering valve  19  is temporarily accumulated to further promote cooling. The vapor phase component inside the intercooler  20  is introduced to a second stage impeller  17   b  of the compressor  17  via a bypass pipe  24  without passing through the evaporator  16 .  
         [0051]    [0051]FIG. 3 shows the internal construction of the compressor  17 . In the figure, reference symbol  25  denotes a casing,  26  a main shaft,  27  a first stage diffuser section,  28  a second stage diffuser section,  29  a return bend,  31  guide vanes,  32  an inlet port and  33  a discharge port. The first stage diffuser section  27  comprises a vane diffuser having a plurality of vanes  27   a  which are arranged spaced at equal intervals on an outer peripheral portion of the first stage impeller  17   a . In the second stage diffuser section  28  are installed in combination; a diffuser  34  having no vanes arranged in a concentric circular shape on the outer periphery of the second stage impeller  17   b , and a vane diffuser  35  having a plurality of vanes  35   a  arranged spaced at equal intervals on the outer periphery of the diffuser  34 . Furthermore, there is provided a gear mechanism  36  for transmitting a drive force from the motor  22 .  
         [0052]    In the compressor  17 , the first stage impeller  17   a  and the second stage impeller  17   b  are both secured to the main shaft  26 , and are rotated by the motor  22 , so that gaseous refrigerant which is drawn in from the inlet port  32 , is compressed (increased in pressure) and then discharged from the discharge port  33 .  
         [0053]    The gaseous refrigerant which is drawn in from the inlet port  32  with rotation of the first stage impeller  17   a , has the velocity and pressure thereof increased by the operation of the first stage impeller  17   a . The velocity is then slowed in the course of passing through the first stage diffuser section  27  so that the kinetic energy is converted into internal energy. Then, after dropping in pressure with sequential passing through the return bend  29  and the guide vanes  31 , this is guided into the entrance of the second stage impeller  17   b . The gaseous refrigerant which has-been drawn in by the rotation of the second stage impeller  17   b , when passing through the second stage impeller  17   b  is further reduced in pressure via a similar passage, and by the process of passing through the second stage diffuser section  28 , the velocity is again slowed down and the kinetic energy converted into internal energy, after which this is discharged from the discharge port  33 .  
         [0054]    In the compressor  17 , one wall portion  34   a  constituting the diffuser  34  is made so as to be able to approach and separate from the other wall  34   b , so that the effect of the diffuser  34  can be adjusted. Hence even if this is combined with the latter stage vane diffuser  35 , and the intake flow rate of the fluid changes, an optimum diffuser effect is obtained.  
         [0055]    [0055]FIG. 4 and FIG. 5 show an adjusting mechanism of the diffuser  34 . In the figures, reference symbol  37  denotes a diffuser ring,  38  a shaft, and  39  a drive section. In the diffuser ring  37  one side face constitutes a wall portion  34   a , and this wall portion  34   a  is exposed to the passage and is built in to the casing  25 , and is supported so as to be able to rotate in the circumferential direction and be able to move in the longitudinal direction of the main shaft  26 .  
         [0056]    In the outer peripheral face of the diffuser ring  37 , as shown in FIG. 6, a groove  37   a  inclined with respect to the lengthwise direction of the main shaft  26 , is formed at three locations at even spacing around the circumference. Furthermore in the casing  25 , protrusions  40  are provided at three locations corresponding to the groove  37   a , for fitting into the grooves  37   a  when the diffuser ring  37  is assembled as described above. In order to suppress rubbing contact with the grooves  37   a , a bearing is provided for each protrusion  40 .  
         [0057]    The shaft  38  is linked to the diffuser ring  37  via a bracket  41  attached to the diffuser ring and protruding outward. The shaft  38  is rotatably supported relative to the bracket  41 , and is driven so as to move back and forth in the lengthwise direction by the drive section  39 .  
         [0058]    In the adjusting mechanism of the diffuser  34 , when the shaft  38  is driven in the lengthwise direction, the linear motion of the shaft  38  is changed to rotary motion of the diffuser ring  37  so that the diffuser ring  37  rotates in the circumferential direction. At this time, the protrusions  40  fitted into the grooves  37   a , guide the diffuser ring  37  along the grooves, however since the grooves  37   a  are formed at an incline with respect to the lengthwise direction of the main shaft  26 , the diffuser ring  37  is also moved along the lengthwise direction of the main shaft  26  in addition to the rotation in the circumferential direction. Consequently, when the shaft  38  is moved in one direction, the diffuser ring  37  is rotated in the circumferential direction and at the same time is pushed in to the passage side so that the one wall  34   a  approaches the other wall  34   b . Moreover, when driven in the other direction, this moves in reverse so that the one wall  34   a  is moved away from the other wall  34   b  and returns to the original position.  
         [0059]    In the drive section  39 , a cylinder mechanism for pushing and pulling the shaft  38  in the lengthwise direction may be adopted, or a rack may be formed on the shaft  38  and this may be engaged with a pinion rotated with a motor or the like, so that the shaft  38  is moved in the lengthwise direction.  
         [0060]    A second embodiment of a turbocompressor and a refrigerating machine according to the present invention as shown in FIG. 7, will now be described. Components already described for the first embodiment are denoted by the same reference symbols and description is omitted.  
         [0061]    [0061]FIG. 7 shows an adjusting mechanism of the diffuser  34 . In this figure, reference symbol  42  denotes a bar, and  43  a drive section. Furthermore, the diffuser ring  37  in this embodiment is only moveable in the lengthwise direction of the main shaft  26 .  
         [0062]    The bar  42  is pivotally supported at an approximate center on the casing  25  so as to be able to swing. One end of the bar  42  is fitted loosely into an aperture  37   b  formed in the diffuser ring  37 , while the other end of the bar  42  is connected to the drive section  43 . The drive section  43  pushes and pulls the other end of the bar  42  to thereby swing the bar  42 .  
         [0063]    In the adjusting mechanism of the diffuser  34 , when the drive section  43  is operated so that the other end of the bar  42  is swung, the one end of the bar  42  swings in the opposite direction according to the theory of levers, so that the diffuser ring  37  connected to the one end of the bar  42  moves in the lengthwise direction of the main shaft  26 . Consequently, when the other end of the bar  42  is swung in one direction, the diffuser ring  37  is pushed in to the passage side and the one wall  34   a  approaches the other wall  34   b . Moreover, when moved in the other direction, this moves in reverse so that the one wall  34   a  is moved away from the other wall  34   b  and returns to the original position.  
         [0064]    A third embodiment of a turbocompressor and a refrigerating machine according to the present invention as shown in FIG. 8, will now be described. Components already described for the aforementioned embodiments are denoted by the same reference symbols and description is omitted.  
         [0065]    [0065]FIG. 8 shows an adjusting mechanism of the diffuser  34 . In the figure, reference symbol  44  denotes a shaft,  45  a connection member, and  46  a drive section. Furthermore, the diffuser ring  37  in this embodiment is only moveable in the lengthwise direction of the main shaft  26 .  
         [0066]    The shaft  44  is supported on the casing  25  further outside than the return bend  29 , and is movable parallel to the lengthwise direction of the main shaft  26 . One end of the shaft  44  is connected to the diffuser ring  37  via the connection member  45 , while the other end of the shaft  44  is connected to the drive section  46 . The drive section  46  pushes and pulls the other end of the shaft  44  so as to move the shaft  44  back and forth in the lengthwise direction.  
         [0067]    In the adjusting mechanism of the diffuser  34 , when the drive section  46  is operated so that the shaft  44  is moved in the lengthwise direction of the main shaft  26 , this movement is transmitted to the diffuser ring  37  via the connection member  45 , and the diffuser ring  37  moves in the lengthwise direction of the main shaft  26 . Consequently, when the shaft  44  is moved in one direction, the diffuser ring  37  is pushed in to the passage side and the one wall  34   a  approaches the other wall  34   b . Moreover, when moved in the other direction, this moves in reverse so that the one wall  34   a  is moved away from the other wall  34   b  and returns to the original position.  
         [0068]    A fourth embodiment of a turbocompressor and a refrigerating machine according to the present invention as shown in FIG. 9, will now be described. Components already described for the aforementioned embodiments are denoted by the same reference symbols and description is omitted.  
         [0069]    [0069]FIG. 9 shows an adjusting mechanism of the diffuser  34 . In the figure, reference symbol  47  denotes a shaft,  48  an eccentric shaft, and  49  a drive section. Furthermore, the diffuser ring  37  in this embodiment is rotatable in the circumferential direction and movable in the lengthwise direction of the main shaft  26 .  
         [0070]    The shaft  47  is disposed outward of the diffuser ring  37  directed in the radial direction thereof and supported on the casing  25 , so as to be rotatable about its own axis which is directed in the radial direction of the diffuser ring  37 . The eccentric shaft  48  is eccentrically provided at one end of the shaft  47  adjacent to the outer peripheral face of the diffuser ring  37 , and is fitted into a hole  37   c  formed in the diffuser ring  37  so as to be rotatable therein. The drive section  49  is connected to the other end of the shaft  47 , so as to rotate the shaft  47 .  
         [0071]    In the adjusting mechanism of the diffuser  34 , when the drive section  49  is operated to rotate the shaft  47 , the eccentric shaft  48  rotates eccentrically, and the rotation movement is transmitted to the diffuser ring  37 , so that the diffuser ring  37  as well as rotating in the circumferential direction is also moved in the lengthwise direction of the main shaft  26 .  
         [0072]    Consequently, when the shaft  47  is rotated in one direction, the diffuser ring  37  is pushed in to the passage side and the one wall  34   a  approaches the other wall  34   b . Moreover, when rotated in the other direction, this moves in reverse so that the one wall  34   a  is moved away from the other wall  34   b  and returns to the original position.  
         [0073]    A fifth embodiment of a turbocompressor and a refrigerating machine according to the present invention as shown in FIG. 10, will now be described. Components already described for the aforementioned embodiments are denoted by the same reference symbols and description is omitted.  
         [0074]    [0074]FIG. 10 shows an adjusting mechanism of the diffuser  34 . In the figure, reference symbol  50  denotes a shaft,  51  an arm section, and  52  a drive section. Furthermore, the diffuser ring  37  in this embodiment is moveable in the lengthwise direction of the main shaft  26 . Moreover, a first helical gear section  37   d  is formed on the outer peripheral face.  
         [0075]    The shaft  50  is disposed further outside than the diffuser ring  37  parallel with the lengthwise direction of the main shaft  26 , and supported on the casing  25  so as to be rotatable about its own axis which is directed in the axial direction of the main shaft  26 . The arm section  51  is secured to one end of the shaft  50  so that with rotation of the shaft  50  the tip end swings. Furthermore, a second helical gear section  51   a  is formed on the tip end of the arm section  51  and this is meshed with the first helical gear section  37   d.    
         [0076]    In the adjusting mechanism of the diffuser  34 , when the drive section  52  is operated to rotate the shaft  50 , the arm section  51  swings, and this swinging is transmitted to the diffuser ring  37  via the second helical gear section  51   a  and the first helical gear section  37   d . Here, since the diffuser ring  37  is only moveable in the lengthwise direction of the main shaft  26 , the force transmitted via the second and first helical gear sections  51   a  and  37   d  becomes just a component in the lengthwise direction of the main shaft  26 . Consequently, when the shaft  50  is rotated in one direction, the diffuser ring  37  is pushed in to the passage side and the one wall  34   a  approaches the other wall  34   b . Moreover, when rotated in the other direction this moves in reverse so that the one wall  34   a  is moved away from the other wall  34   b  and returns to the original position.  
         [0077]    As described above, in the turbocompressor according to the present invention, the linear motion of the shaft is converted directly into rotary motion of the diffuser ring, and due to the relationship between the groove and the protrusion, the diffuser ring moves in the axial direction while rotating. Therefore it becomes possible to move the diffuser in the axial direction using a drive section which performs simple linear motion. As a result, the number of ring shape members can be reduced compared to heretofore, and the construction simplified. Therefore the effect is obtained that, the mechanism itself can be made compact, and due to a decrease in sliding parts, energy losses can be reduced, and due to a reduction in the number of parts, time and labor in processing can be minimized.  
         [0078]    According to the turbocompressor of the second aspect, since the effect of the diffuser can be adjusted, if a vane diffuser is combined on the outside thereof, then even if the fluid intake flow rate is changed, an optimum diffuser affect is obtained.  
         [0079]    In the turbocompressor of the third aspect, by swinging the bar, the diffuser ring can be moved in the axial direction. Therefore the diffuser ring can be moved in the axial direction using a drive section which performs simple linear motion. As a result an affect similar to the above is obtained.  
         [0080]    According to the turbocompressor of the fourth aspect, by moving the shaft in the axial direction of the impeller, the diffuser ring is moved in the axial direction. Therefore, the diffuser ring can be moved in the axial direction using a drive section which performs simple linear motion. As a result, an affect similar to the above is obtained.  
         [0081]    According to the turbocompressor of the fifth aspect, by rotating the shaft, the diffuser ring is moved in the axial direction. Therefore the diffuser can be moved in the axial direction using a drive section which performs simple rotary motion. As a result, an affect similar to the above is obtained.  
         [0082]    According to the turbocompressor of the sixth aspect, by rotating the shaft, the diffuser ring is moved in the axial direction. Therefore the diffuser ring can be moved in the axial direction using a drive section which performs simply rotary motion. As a result, an affect similar to the above is obtained.  
         [0083]    According to the refrigerating machine of the seventh aspect, for the turbocompressor the aforementioned affect is obtained. Therefore for the refrigerating machine also, it is possible to realize compactness of the equipment, energy saving, and low cost.