Patent Publication Number: US-7217109-B2

Title: Scroll type hydraulic machine

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a scroll type hydraulic machine suitable as a compressor for a refrigerating circuit constituting an air conditioning system. 
   2. Description of the Related Art 
   This type of hydraulic machine, that is, a scroll type compressor is provided to a refrigerating circuit, and is disposed in an automobile, for example, inside an engine room. More specifically, a compressor is connected to an evaporator, a condenser as well as an expansion valve. These condenser and expansion valve are disposed inside the engine room while the evaporator is disposed in a vehicle interior. 
   This compressor comprises a scroll unit, that is, a stationary scroll as well as a movable scroll, inside a compression casing, suctions refrigerant from the evaporator side and compresses by causing the movable scroll to rotate with respect to the stationary scroll and discharge this compressed refrigerant toward the condenser side. 
   In order to implement swivel actions of this movable scroll, it is necessary to intercept the shaft center of the stationary scroll, that is, rotation of the movable scroll around the rotation center without preventing orbital rotation of the movable scroll around the orbital center. Therefore, as a rotation interception mechanism for intercepting this rotation, such a compressor is known that comprises a plurality of binding members for binding its rotation between a drive casing and a substrate of the movable scroll, and brings these binding members into pin connection to both of the drive casing and the movable scroll (reference should be made to, for example, Japanese Laid-Open patent (Kokai) Publication No. 2001-90678). 
   According to this compressor, the swivel side pin and the fixed side pin are disposed in such a position that is determined from the orbital center and the rotation center so as to alleviate the load onto the pins, in such a position in which the volume of the compressing chamber reaches 20% to 28% of the volume at the time of completion of suction of fluid. 
   It should be added that, there exist three reference points in the movable scroll, that is, the above-mentioned orbital center as well as rotation center and, in addition, a gravity center. Further, in general, this rotation center is employed as the center of the substrate of the movable scroll. That is because the production of the scroll unit becomes easy. 
   Here, there is no problem in the case where the gravity center of the movable scroll and the rotation center match. On the other hand, the gravity center and the rotation center are disposed at slight distance and therefore do not match. That is because it is necessary to make the size in the scroll unit&#39;s radius direction smaller at the time of engagement between the stationary scroll and the movable scroll. 
   Further, the displacement quantity being distance between the gravity center and the rotation center generates torque around the rotation center by being multiplied by the centrifugal force arising in the movable scroll. That is, a load other than the original rotation intercepting force will arise in the pin of the rotation interception mechanism. In particular, since the above-mentioned centrifugal force is proportionate to the square of the rotation speed,-an excess load arises at the time of high speed, and the decrease in durability of the rotation interception mechanism is concerned. 
   However, the above-mentioned prior art determines disposition of the pin from the relationship between the orbital center and the rotation center with the gravity center of the movable scroll and the rotation center match as a precondition. In other words, on a problem in the case where the above-mentioned gravity center and rotation center do not match, no particular consideration is paid and the problems on the point of load decrease in pins still remain. 
   SUMMARY OF THE INVENTION 
   The present invention has been attained in view of such a problem and an object thereof is to provide a scroll type hydraulic machine capable of alleviating the load of the pin and of achieving the improvement in the durability of a rotation interception mechanism. 
   In an attempt to attain the above-mentioned object, the scroll type hydraulic machine of the present invention comprises a housing having a drive casing as well as a compression casing; a drive shaft extending inside the drive casing and rotatably supported by the drive casing through a bearing; and a scroll unit housed inside the compression casing and executing a series of processes of suction, compression and discharge of refrigerant driven by the drive shaft, and this unit comprises a movable scroll that is driven by drive shaft and implements swivel movement around an orbital center being a shaft center of a stationary scroll; and rotation interception mechanisms disposed in plurality on a substrate side of the movable scroll and for intercepting the operations of the movable scroll around the rotation center without interfering swivel movements of the movable scroll, wherein the respective rotation interception mechanisms are mounted to intervene between the drive casing and the substrate of the movable scroll, and include a binding member for binding rotation of the movable scroll, a fixed side pin provided with protrusion in the drive casing to get engaged with the binding member, and a swivel side pin provided with protrusion in the movable scroll to get engaged with the binding member for being restrained by the binding member and swiveling around the shaft center of the fixed side pin, and comprises load alleviation means for alleviating loads onto the fixed side pin and the swivel side pin caused by the torque due to the distance between the gravity center and the rotation center of the movable scroll and the centrifugal force. 
   Therefore, according to the scroll type hydraulic machine of the present invention, it is presupposed that the gravity center of the movable scroll and the rotation center of this movable scroll do not match, and these distance and centrifugal force give rise to torque. Further, a load due to this torque acts on the fixed side pin and the swivel side pin. However, since the load alleviation means alleviates this load, the durability of the rotation interception mechanism is improved. Accordingly, it attributes to the improvement in reliability of the scroll type hydraulic machine. 
   In addition, preferably, the load alleviation means is a hole provided to the movable scroll in a position being axisymmetric to a straight line connecting the gravity center to the rotation center, and a swivel side pin is disposed to this hole and thereby the load caused by torque is alleviated. Moreover, the load alleviation means is a hole provided to the drive casing in a position being axisymmetric to a straight line connecting the gravity center to the orbital center, and a fixed side pin is disposed to this hole and thereby the load caused by torque is alleviated. 
   Thus, even if a load caused by torque arises, this load is equally distributed and acts to the fixed side pin or the swivel side pin disposed in a position being axisymmetric to the gravity center as reference. That is, in this case, without changing distance between the gravity center and the rotation center anyhow, the load arising in the pin can be reduced. In addition, consequently, the enlargement in diameter size of the pins is avoided, and the decrease in diameter size of the housing becomes attainable. Moreover, there will be no need to increase the number of units of the pin, which allows the reduction in manufacturing costs of hydraulic machines. 
   More preferably, the load alleviation means is a weight alleviation portion disposed in a substrate of a movable scroll at a position closer to the gravity center from the rotation center, and alleviates the load caused by torque. In addition, the load alleviation means is a weight increasing means disposed in a substrate of a movable scroll at a position on an opposite side against the gravity center side from the rotation center, and alleviates a load caused by torque. 
   Thus, a weight alleviation portion is provided in the substrate, and thereby the gravity center of the movable scroll is caused to approach toward the rotation center. Accordingly, in this case, the distance between the gravity center and the rotation center is minimized, so that torque is minimized, and therefore a load arising in the pin can be reduced. In addition, also in this case, the enlargement in diameter size of the pins is avoided, and there will be no need to increase the number of units of the pin. 
   In addition, an eccentric bush protruding from the substrate of the movable scroll toward the drive casing side and being disposed in an eccentric state from the shaft center of the drive shaft is provided with a rotatably supported boss, and the load alleviation means is a boss disposed in the movable scroll by causing the shaft center of the boss to move from the rotation center toward the gravity center side, and alleviates the load caused by torque. 
   Thereby, the shaft center of the boss rotationally supporting the eccentric bush is caused to move toward the gravity center side, and this boss is disposed in an eccentric state to a conventional rotation center. In other wards, in this case, the rotation center of the movable scroll is made closer to the gravity center. Accordingly, also in this case, the distance between the gravity center and the rotation center is minimized, so that torque is minimized, and therefore a load arising in the pin can be reduced. In addition, the enlargement in diameter size of the pins is avoided, and there will be no need to increase the number of units of the pin. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus, are not limitative of the present invention, and wherein: 
       FIG. 1  is a sectional view of the configuration of the scroll type hydraulic machine in accordance with first embodiment of the present invention; 
       FIG. 2  is a front view of a movable scroll along a II—II line in  FIG. 1 ; 
       FIG. 3  is an explanatory diagram of a load onto a rotation interception mechanism in  FIG. 1 ; 
       FIG. 4(   a ) is a front view of the movable scroll in second embodiment and  FIG. 4(   b ) is a sectional view along a IV—IV line viewed from the direction of arrows; and 
       FIG. 5  is a rear view of the movable scroll in third embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will be described with the drawings as follows.  FIG. 1  shows a scroll type hydraulic machine in accordance with the present embodiment. 
   The hydraulic machine  4  is a rotational scroll type compressor provided with a housing  20 . The housing  20  has a drive casing  22  as well as a compression casing  24 . The casing  22  is shaped to be cylindrical with steps having diameter getting larger and larger toward the casing  24 , and has two ends both being open respectively. On the other hand, the casing  24  is shaped like a cup opening toward the end with the larger diameter of the casing  22 , and the open end is air-tightly fitted to the large diameter end of the casing  22  and connected to the casing  22  through a plurality of connection screws  28 . 
   Inside the casing  22 , a drive shaft  30  is disposed. This drive shaft  30  also has a stepped shape, and has a small-diameter shaft portion  32  on the side of one end and a large-diameter shaft portion  34  on the side of the other end. The shaft portion  32  protrudes from a small-diameter end of the casing  22  and a drive disk  42  is attached to the protruding end through a nut  44 . The disk  42  is connected to a drive pulley  48  though an electromagnetic crutch  46 , and this pulley  48  is rotatably supported by the casing  22  through a pulley bearing  50 . 
   The shaft portion  34  is rotatably supported by the casing  22  through a needle bearing  36 . In addition, the shaft portion  32  is also rotatably supported by the casing  22  through a ball bearing  38 . Moreover, inside the casing  22 , a lip seal  40  is disposed between the bearing  38  and the bearing  36 , and this seal  40  is brought into relative sliding contact with the shaft  32  so as to zone the interior of the casing  22  in an air-tight state. When the crutch  46  is operated ON, the crutch  46  connects the pulley  48  and the disk  42  integrally and causes the drive shaft  30  to rotate in one direction together with the pulley  48 . In contrast, when the crutch  46  is operated OFF, the crutch  46  cancels the connection between the pulley  48  and the disk  42  to terminate the transmission of power of the drive shaft  30  off the pulley  48 . 
   Here, a scroll unit  52  is housed in the casing  24 , and this unit  52  is provided with a movable scroll  54  and a stationary scroll  56 . These scrolls  54  and  56  respectively have such scroll wraps  61  and  79  that are engaged with each other, and these wraps  61  and  79  cooperate each other to form a compression chamber  58  through a chip seal  55 , etc. This compression chamber  58  moves toward the center of the wraps  61  and  79  from the outer circumference side in the radius direction with rotary movement of the scroll  54 , and at that time, its volume is decreased. 
   In order to attain the rotary movement of the above-mentioned scroll  54 , the substrate  60  of the scroll  54  has a boss  62  protruding toward the side of the casing  22 , and this boss  62  is rotatably supported by an eccentric bush  66  through the bearing  64 . This bush  66  is supported by the crank pin  68 , and this pin  68  protrudes eccentrically from the shaft portion  34 . Therefore, with rotation of the drive shaft  30 , the scroll  54  will implement swivel movement through the pin  68  and the bush  66 . In addition, a counter weight  70  is mounted between the bush  66  and the shaft portion  34  through a connection pin  71  and this weight  70  is configured by laminating a plurality of large and small circular plates and will become a balance weight for the swivel movement of the scroll  54 . 
   The scroll  56  is fixed inside the casing  24 , and the substrate  78  partitions the interior of the casing  24  into the compression chamber  58  and a discharge chamber  80 . A discharge hole  82  communicated to the compression chamber  58  is formed at the center of the substrate  78 , and this discharge hole  82  is opened and closed with a lead valve  84 . This lead valve  84  together with its valve guard  86  is mounted to the exterior plane of the substrate  78  through a bolt  87 . Here, while not shown diagrammatically, in the peripheral wall of the casing  24 , an intake port and a discharge port are formed which are brought in communication with the compression chamber  58  and the discharge port  80  respectively. The intake port is connected to the above-mentioned evaporator, and the discharge port is connected to the condenser. 
   With rotation of the drive shaft  30 , in the above-mentioned compressor  4 , the scroll  54  implements swivel movement around the shaft center of the stationary scroll  56 , that is, around the orbital center O S  of the movable scroll  54  through the pin  68  and the bush  66 . At this occasion, the rotation of the scroll  54  is in an intercepted state by the operation of four rotation interception mechanisms  10 . Consequently, the scroll  54  implements swivel movement with respect to the scroll  56  in such a state as to keep its swivel posture constantly, which swivel movement suctions the refrigerant into the compression chamber  58  through the intake port, compresses this refrigerant and discharges the compressed refrigerant into the discharge chamber  80  to execute a series of processes. Thereafter, the compressed refrigerant is supplied to the condenser through the discharge port from the discharge chamber  80 . 
   The above-mentioned mechanism  10  is provided with a binding member  11  mounted between the large diameter end of the casing  22  and the substrate  60  of the scroll  54 . This member  11  is formed to have the shape of an approximately ellipse and is brought into pin coupling to the casing  22  and the scroll  54 . Specifically, the movable scroll  54  is provided with four pin fitting holes (load alleviation means)  54   h  at an equal interval, and the casing  22  is also provided with four pin fitting holes (load alleviation means)  22   h  at an equal interval. Further, the swivel side pin  15  and the fixed side pin  14  are disposed in the longitudinal direction of the member  11  at a distance, are respectively engaged to the above-mentioned fitting holes  54   h  and the fitting holes  22   h , and are disposed in the scroll  54  and the casing  22  so as to protrude. 
   Further in detail, as shown in  FIG. 2 , the scroll  54  is arranged to have the center of the substrate  60  being the rotation center O R , and the distance between this rotation center O R  and the above-mentioned orbital center O S  is taken as the swivel radius r of the swivel side pin  15  with respect to the fixed side pin  14 . In contrast, the gravity center O of the scroll  54  is positioned corresponding to the vicinity of the tip of the wrap  61 , and does not match the rotation center O R , and distance (displacement amount) L is present between these gravity center O and the rotation center O R . 
   Four fitting holes  54   h  in the present embodiment do not take the straight line connecting the rotation center O R  to the orbital center O S  as a reference in the respective swivel positions due to orbital rotation of the scroll  54 , but take a straight line S connecting the gravity center O to the rotation center O R  as a reference, to which straight line S the four fitting holes  54   h  are disposed in positions being axisymmetric, and they are respectively engaged with the swivel side pin  15 . In other words, the fitting holes  54   h  are, as shown in the drawings, disposed in such a position in which an angle θ made by the straight line S passing the gravity center O and the rotation center O R  and a straight line connecting the center of respective fitting holes  54   h  to the rotation center O R  gives 45° in the present embodiment, and the respective fitting holes  54   h  are disposed in opposition to the rotation center O R . 
   On the other hand, the four fitting holes  22   h  of the present embodiment take the straight line connecting the gravity center O to the orbital center O S  as a reference in respective swivel positions due to orbital rotation of the scroll  54  as a reference, are disposed in positions being axisymmetric to the straight line, and are respectively engaged with the fixed side pin  14 . Specifically, the fitting holes  22   h , while not shown in  FIG. 2 , are always disposed in such a position in which the angle made by respective straight lines connecting the centers of the respective fitting holes  22   h  and the orbital center O S  gives 90° in the present embodiment, and the respective fitting holes  22   h  are disposed in opposition to the orbital center O S . 
   Thus, the positional relationship between the swivel side pin  15  engaged with one binding member  11  and the fixed side pin  14  corresponds with the positional relationship between the rotation center O R  and the orbital center O S . Further, the dispositions of the fitting holes  54   h  and the fitting holes  22   h  engaged to these swivel side pin  15  and fixed side pin  14  alleviates load F P  to the swivel side pin  15  and the fixed side pin  14  caused by torque M around the rotation center O R  determined by multiplication of distance L by centrifugal force F C . 
   Further details will be shown in  FIG. 3 . Here, in this drawing, for convenience in description, four rotation interception mechanisms  10  are disposed in the front side of the movable scroll  54 . 
   When the scroll  54  implements orbital rotation in the rotary direction R around the orbital center O S  of the scroll  56 , the swivel side pin  15  swivels around the fixed side pin  14  while being restrained by the member  11 . At first, in a state (I) where the gravity center O, the rotation center O R  and the orbital center O S  aligns in this order from the above, the centrifugal force F C  arises upward at the gravity center O, and this direction corresponds with the direction of a straight line connecting the gravity center O to the rotation center O R , so that no torque M due to the above-mentioned centrifugal force F C  arises. 
   Next, in a state (II) where the swivel side pin  15  swivels around the fixed side pin  14  by 90° from the above-mentioned state (I), the centrifugal force F C  arises leftward, and this direction is perpendicular to the direction of the straight line connecting the gravity center O to the rotation center O R . Therefore, the torque M by the above-mentioned centrifugal force F C  will be maximized as shown in the drawing, and the load onto the fixed side pin  14  and the swivel side pine  15  will become the largest. However, as described above, any of the fitting holes  54   b  and the fitting holes  22   h  of the present embodiment is disposed uniformly with the gravity center O as a reference, and the load F P  accompanied by this torque M will be, as shown in the drawing, distributed uniformly to the two rotation interception mechanisms  10 ,  10  positioned on the side of the gravity center O from the rotation center O R  in a more alleviated state where no gravity center O is taken into consideration than in a conventional case. 
   In addition, in a state (III) where the swivel side pin  15  further swivels around the fixed side pin  14  by 90°, the centrifugal force F C  arises downward, and this direction corresponds with the direction of the straight line connecting the gravity center O and the rotation center O R , so that no torque M due to the above-mentioned centrifugal force F C  arises. 
   On the other hand, in a state (IV) where the swivel side pin  15  further swivels around the fixed side pin  14  by 90°, the centrifugal force F C  arises rightward, and this direction is perpendicular to the direction of the straight line connecting the gravity center O to the rotation center O R . Accordingly, as shown in the drawing, the torque M due to the above-mentioned centrifugal force F C  will be maximized again, and the load onto the fixed side pin  14  and the swivel side pin  15  will become the largest. However, also in this case, the load F P  accompanied by this torque M is, as shown in the drawing, is alleviated more than in conventional cases, and distributed uniformly to the two rotation interception mechanisms  10 ,  10  positioned closer to the side of the gravity center O from the rotation center O R . 
   Thus, in the present embodiment, attention has been focused on the point that the gravity center O of a movable scroll  54  does not correspond with the rotation center O R . The relationship between distance L between them and the centrifugal force F C  gives rise to torque M, and a load accompanied by this torque M acts on a fixed side pin  14  and a swivel side pin  15 . However, fitting holes  54   h  are disposed in positions axisymmetric to a straight line S connecting the gravity center O to the rotation center O R  and, therefore, a load F P  is distributed uniformly to the fixed side pin  14  and the swivel side pin  15  of the two rotation interception mechanisms  10 ,  10  in an alleviated state so as to avoid the concentration of a large load accompanied by the torque M onto the rotation interception mechanisms. Consequently, breakage in the fixed side pin  14  and the swivel side pin  15  is avoided at the time of high-speed rotation in particular and the durability of the rotation interception mechanisms is improved to attribute to the improvement in reliability of the compressor. 
   In addition, the enlargement in diameter size of the fixed side pin  14  and the swivel side pin  15  is avoided, and moreover the size in the radius direction of the scroll unit  52  becomes smaller at the time of engagement between the scroll  56  and the scroll  54 , so that the decrease in size of the casing  24  becomes attainable. Moreover, since there will be no need to increase the number of units of the fixed side pin  14  and the swivel side pin  15 , the reduction in manufacturing costs of the compressors can be achieved. Further, the rotation center O R  is taken as the center of the substrate  60 , which also attributes to the reduction in manufacturing costs of the unit  52 . 
   It should be added that, in the above-mentioned embodiment, without any changes in distance L between the gravity center O and the rotation center O R , the reduction in loads arising in the fixed side pin  14  and the swivel side pin  15  has been achieved. However, the loads which arise in the respective pins may be reduced by trying to minimize this distance. 
   Specifically, as shown in  FIG. 4 , the substrate  60 A of the movable scroll  54 A is provided with cylindrical concave portion (weight alleviation portion)  90  as load alleviation means in a position of the side of the gravity center O from the rotation center O R  on a line connecting the gravity center O positioned in the vicinity of the wrap  61  and the rotation center O R  being the center of the substrate  60 A. In this case, the gravity center O is caused to get closer toward the rotation center O R  being the shaft center of the boss  62 A as well, so that the displacement amount between the gravity center O and the rotation center O R  will become shorter to distance L 1  than in conventional cases, and the above-mentioned torque will become the minimum regardless of the position of the swivel side pin  15 A. Consequently, loads which arise in the respective pins can be reduced. In addition, the enlargement in diameter size of the respective pins is avoided, and the number of units thereof does not need to be increased. 
   Moreover, as in the above-mentioned drawing, the substrate  60 A may be provided with a cylindrical weight (weight increasing portion)  92  as load alleviation means in a position on the side in opposition to the side of the gravity center O from the rotation center O R  on a line connecting the gravity center O to the rotation center O R . This weight  92  is larger in specific gravity than the material of the scroll  54 A, and also in this case, the gravity center O will be caused to get closer toward the rotation center O R , so that the displacement amount between the gravity center O and the rotation center O R  will become shorter to distance L 1  than in conventional cases. Therefore, regardless of the position of the swivel side pin  15 A, the above-mentioned torque will become the minimum. Here, as shown in the above-mentioned drawing, a weight  92  together with the concave portion  90  may be provided, or the substrate  60 A may be provided with either this concave portion  90  or a weight  92 . 
   On the other hand, for reduction in a load arising in the respective pins due to the minimization of the distance between the gravity center O and the rotation center O R , as shown in  FIG. 5 , the shaft center of the boss (load alleviation means)  62 B provided in the substrate  60 B of the movable  54 B may be moved to the side of the gravity center O from a conventional rotation center O R ′ for disposition. Thus, even if the boss  62 B is caused to get closer to the gravity center O and made eccentric, the displacement amount between the gravity center O and the rotation center O R  according to the present embodiment will get shorter to distance L 2  than in conventional cases, so that regardless of the position of the swivel side pin  15 B, the above-mentioned torque will become the minimum, and the load arising in the respective pins can be reduced. In addition, the enlargement in diameter size of the respective pins is avoided, and there will be no need to increase the number of units thereof. 
   In addition, in the above-mentioned respective embodiments, four binding members are disposed at an equal distance, but the present invention will not be necessarily limited to this embodiment with a specified number of units. 
   The invention thus described, it will he obvious that the same may be varied in many ways. Such variations are not, to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.