EP2524139A2

EP2524139A2 - Compressor having suction throttle valve

Info

Publication number: EP2524139A2
Application number: EP11705041A
Authority: EP
Inventors: Norio Suzuki
Original assignee: Valeo Japan Co Ltd
Current assignee: Valeo Japan Co Ltd
Priority date: 2010-01-12
Filing date: 2011-01-12
Publication date: 2012-11-21
Also published as: WO2011086907A3; WO2011086907A2

Abstract

In a compressor provided with a suction throttle valve capable of reducing a low pressure pulsation by constricting a suction passage, a performance deterioration caused by an internal leakage of pressure guided to the suction throttle valve is decreased even when a suction control valve is configured by a spool valve. In a direction substantially perpendicular to an orientation of refrigerant flowing through a suction passage 36, a suction throttle valve 60 for adjusting a passage area of the suction passage 36 is provided, working fluid discharged to a discharge chamber 34 is guided to one end side of the suction throttle valve 60, the working fluid flowing in a suction chamber 33 is guided to the other end side of the suction throttle valve 60, and at the same time, a spring 63 for biasing the suction throttle valve 60 toward the one end side is provided. The suction throttle valve 60 is configured by a small diameter portion 61a slidably housed in a small hole portion 62a formed in a housing and a large diameter portion 61b formed consecutively with the small hole portion 62a and slidably housed in a large hole portion 62b provided to cross the suction passage 36.

Description

COMPRESSOR

The present invention relates to a piston-type compressor including a mechanism for preventing generation of abnormal noise due to the propagation of pressure pulsation, which is caused by self-induced vibration of a suction valve, to outside the compressor, and more particularly, relates to a compressor which can diminish the propagation of the pressure pulsation to outside the compressor by constricting a suction passage in an operating range in which the pressure pulsation is generated and prevent the performance from being deteriorated due to the constriction of the suction passage in the operating range in which the pressure pulsation is not generated.

In piston-type compressors, a stopper having a predetermined depth is formed at a position facing a distal end of a suction valve of a cylinder block, and thus the distal end of the suction valve abuts the stopper when refrigerant gas is suctioned in a cylinder bore, thereby preventing generation of self-induced vibration in the suction valve.

In a piston-type variable capacity compressor, however, the amount of the gas suctioned in the cylinder bore is different according to a maximum capacity state and a variable capacity state. If the depth of the stopper is set according to the maximum capacity state, since a displacement amount of the suction valve is small, in particular, in a small capacity state, the distal end of the suction valve does not come in contact with the stopper. For this reason, the suction valve causes the self-induced vibration, and thus pressure pulsation is generated in a suction chamber. As a result, there is a drawback that the suction valve generates the self-induced vibration, resulting in pressure variation of the suction chamber, and the pressure pulsation is propagated to outside the compressor thereby to generate abnormal noise.

Therefore, it is considered in a compressor of the conventional technology, as discussed in Patent Literature 1 below, that a suction passage of the compressor is provided with an opening control valve for controlling its opening area, and the opening control valve is operated by differential pressure generated by the flow of the gas in the suction passage and a spring force. Thus, the suction passage is constricted when a suction flow rate is small, so that the suction pulsation generated in the small capacity state is prevented from being propagated to outside the compressor, and the opening area of the suction passage is increased when the suction flow rate is high.

In the configuration of the above-described Patent Literature 1, however, there is a drawback that since the opening control valve is operated by the differential pressure generated by the flow of the gas in the suction passage and the spring force, if the spring force is set to be strong with the emphasis on the reduction of the pulsation, then the suction passage is constricted even in the maximum capacity state and thus cooling capacity is deteriorated; on the contrary, if the spring force is set to be weak with the emphasis on the cooling capacity in the maximum capacity state, then the pulsation is not sufficiently reduced in the low capacity state which requires the effect of constriction.

In addition, in the above-described opening control valve, since the opening control valve is provided in an orientation facing the direction of the gas flowing through the suction passage (to be operated in the flow direction of the gas in the suction passage), when the suction gas pushes and opens the opening control valve and then flows into a suction chamber, the suction gas collides with the opening control valve, and thus the flow orientation should be changed in a right angle direction, thereby blocking the smooth flow of the suction refrigerant.

Therefore, for example, a clutchless compressor is considered in the conventional technology, as discussed in Patent Literature 2, that in the midway of the suction passage, there is provided a suction control valve configured by a spool valve which slides in a direction perpendicular to the suction passage; one end of the suction control valve is supplied with refrigerant gas of a discharge chamber, and the other end of the spool valve is supplied with refrigerant gas of a crank chamber; the opening degree of the suction passage is increased in the large capacity state in which the pressure of the discharge chamber is increased, while the opening degree of the suction passage is reduced in the small capacity state in which the pressure of the discharge chamber is decreased. In particular, in the suction control valve discussed in Patent Literature 2, the spool valve is placed in a direction perpendicular to a central axis of a shaft, so that the whole length of the spool valve is lengthened and a sliding portion of the spool valve is lengthened, thereby preventing deterioration of its performance and operability by suppressing the leakage of the refrigerant gas from the spool valve.

Japanese Unexamined Patent Publication No. 2000-136776 Japanese Unexamined Patent Publication No. 2002-31049

In the configuration of the above-described spool valve, however, there is a drawback that since a cylindrical portion (referred to as a cylindrical portion on a high-pressure side) which is exerted by the high-pressure gas from the discharge chamber and a cylindrical portion (referred to as a cylindrical portion on a low-pressure side) which is exerted by the pressure from the crank chamber have a substantially same diameter, the diameter of the cylindrical portion which is exerted by the high-pressure gas is large, and thus the amount of the refrigerant leaked to the suction passage from the high-pressure side via a clearance around the cylindrical portion is large, thereby causing the performance of the compressor to deteriorate.

In order to cope with the drawback, it is possible to reduce the clearance around the cylindrical portion on the high-pressure side. In a case where the clearance is reduced to 15 micron, as shown in Fig. 7, it tends to be improved to some extents. As compared with the case in which there is no suction control valve, however, it is shown that the entire performance is reduced by about 2% to about 4%. For this reason, it is necessary to set the clearance to be smaller when attempting to obtain the better performance by adjusting the clearance. However, it is hard to further reduce the clearance in the light of tolerance management, and the clearance is likely to be clogged with contaminants existing in working fluid, which impedes the operation of the valve body.

For this reason, since there is a limit to the improvement in the performance only by adjusting the clearance of the spool valve to suppress the leakage of the working fluid, it is considered to seal the clearance by attaching a seal member such as an O-ring on an outer peripheral surface of the cylindrical portion.

However, since a valve sliding hole 62 into which the spool valve is inserted is formed to be substantially perpendicular to a suction passage 36, an edge E as shown in Fig. 8 is formed at a portion in which the suction passage 36 crosses the valve sliding hole 62. In the above-described spool valve S with the configuration where a cylindrical portion S1 which is exerted by the high-pressure gas and a cylindrical portion S2 which is exerted by the pressure of the crank chamber are formed to have the same diameter, there is a drawback that when the spool valve S is inserted into the valve sliding hole 62 with a seal member (O-ring) 52 being attached to the periphery of the cylindrical portion S1 of the spool valve S, the seal member (O-ring) 52 is caught by the edge E, so that the seal member (O-ring) 52 may be cut.

Accordingly, the present invention has been achieved in view of the above-described circumstances, and a primary object of the present invention is to provide a compressor including a suction throttle valve capable of decreasing low-pressure pulsation by constricting a suction passage in an operating range where the low-pressure pulsation is likely to occur thereby to decrease or prevent performance deterioration which is caused by internal leakage of pressure led to the suction throttle valve when the suction control valve is formed from a spool valve.

In addition, a primary object is to provide a compressor capable of preventing the seal member from being cut when the suction throttle valve provided with the seal member is inserted into a valve sliding hole even in a case of using a seal member to prevent internal leakage of pressure led to a suction throttle valve.
Moreover, another object of the present invention is to prevent a drawback that contaminants clog in a clearance between the valve body of the suction throttle valve and a valve sliding hole into which the valve body is inserted, resulting in an operation of the valve body being hindered.

To achieve the above-described objects, a compressor according to the present invention comprises: a drive shaft rotatably journaled to a housing; a plurality of pistons reciprocating in an axial direction by rotation of the drive shaft; a cylinder block formed with a plurality of cylinder bores through which the plurality of pistons slide and configuring a compression mechanism together with the pistons; and a cylinder head provided at an end of the cylinder block, which cylinder head includes: a suction chamber, into which working fluid suctioned into the compression mechanism via each suction hole being opened and closed by suction valves provided to correspond to the respective cylinder bores flows from a suction inlet; and a discharge area where the working fluid compressed by the compression mechanism is discharged via each discharge hole being opened and closed by discharge valves provided to correspond to the respective cylinder bores, the compressor further comprising: a suction passage that guides refrigerant suctioned from the suction inlet into the suction chamber; a suction throttle valve provided in a midway of the suction passage and moving in a direction substantially perpendicular to an orientation of the refrigerant flowing through the suction passage, thereby adjusting a passage area of the refrigerant passing through the suction passage; and a spring that biases the suction throttle valve, wherein the working fluid discharged to the discharge area is guided toward one end side of the suction throttle valve and the working fluid flowing into the suction chamber is guided toward the other end side of the suction throttle valve, the suction throttle valve is biased in a direction of enlarging the passage area of the suction passage by the working fluid exerting at one end side of the suction throttle valve, and the suction throttle valve is biased in a direction of reducing the passage area of the suction passage by the working fluid exerting at the other end side of the suction throttle valve and a spring force of the spring, and the suction throttle valve includes a small diameter portion and a large diameter portion which is formed consecutively with the small diameter portion, and the small diameter portion is slidably housed in a small hole portion which is formed in the housing, and the large diameter portion is slidably housed in a large hole portion which is crossing the suction passage and has an inner diameter which is larger than that of the small hole portion.

Therefore, since the suction throttle valve is provided perpendicular to the suction passage, the suction passage will not be constricted due to the spring force, and it is possible to ensure the smooth flow of the suction gas without a change in the flow direction of the suction gas due to collision with the suction throttle valve.
Further, since the passage area of the suction passage is adjusted based on the difference in pressure between the high-pressure area and the suction area, the propagation of the suction pulsation can be suppressed by constricting the suction passage in a low load state where a low-pressure pulsation is generated, and a drawback that the performance is deteriorated as a result of constricting the suction passage in a high load state where no low-pressure pulsation is generated and thus there is no need of constricting the suction passage can be reduced. In this way, it is possible to realize both the securing of the cooling capability by corresponding to each load condition and the reduction of the pulsation.

In particular, in the above-described configuration, since the suction throttle valve is configured to include a small diameter portion which is slidably housed in a small hole portion formed in the housing, and a large diameter which is slidably housed in a large hole portion formed consecutively with the small hole portion while crossing the suction passage, the amount of the refrigerant leaked to the suction passage from the high-pressure side through the clearance around the small diameter portion can be reduced, and even when the seal member is provided on the outer peripheral surface of the small diameter portion in order to prevent the refrigerant leakage in this portion, the seal member will not contact the edge formed in a portion where the suction passage and the large diameter portion cross, minimizing the risk of damage.

Herein, as a specific configuration example of the above-described suction throttle valve, when the housing is configured to include the cylinder block; and a cylinder head assembled to an end of the cylinder block via a valve plate, it can be configured such that the suction throttle valve is provided at the cylinder head and configured to include a valve body having the small diameter portion which is slidably housed in the small hole portion formed in the cylinder head, a large diameter portion which is formed consecutively with the small hole portion and is slidably housed in the large hole portion crossing the suction passage, a stopper portion which is provided at an end of the large diameter portion at the small diameter portion side to prevent the suction passage from being completely closed by the large diameter portion, and a relief portion which is provided between the small diameter portion and the stopper portion and has a diameter smaller than a diameter of the small diameter portion, and it can be configured such that the working fluid discharged to the discharge area is supplied to a distal end surface of the small diameter portion, the working fluid flowing into the suction chamber is supplied to a rear surface of the large diameter portion, and the valve body is biased toward a side of the small diameter portion by a spring which is provided on the rear surface of the valve body.

In such a configuration, the suction passage will not fully be closed even when the valve body is set to the minimum opening position because the movement of the valve body is restricted by the stopper portion, and since the fitting length between the small diameter portion and the small hole portion is shortened, thus even when contaminants enters, the contaminants are made to pass through the shortened fitting length, and thus are easily discharged to the low pressure side. Further, when the valve body is set to the maximum opening position, the passage area of the suction passage will not be narrowed when the relief portion is made to face the suction passage, thereby making it possible to suppress a suction resistance.

It can be also configured such that on the outer peripheral surface of the small diameter portion of the suction throttle valve, a seal member is provided to seal between the outer peripheral surface of the small diameter portion and the inner peripheral surface of the small hole portion (to block the clearance).
According to such a configuration, since the clearance between the small diameter portion and the small hole portion of the suction throttle valve is sealed by the seal member provided on the outer peripheral surface of the small diameter portion by the seal member, it is possible to prevent the working fluid from being leaked from the one end side of the suction throttle valve to the suction passage.

It is preferable that the above-described seal member can be suitable for the small diameter portion having a small diameter, and use an O-ring, for example.

It is confirmed that the above-described seal member cannot easily slide along the small hole portion as the hardness is greater and can easily slide along the small hole portion as the hardness is smaller. According to the studies made by the present inventors, it is preferable that the seal member is imparted with a hardness of about A30 to A50 because it is then possible to secure the smooth movement of the small hole portion and to reduce any particular production problem in view of the fact that when the hardness is equal to or more than A60, it is not possible to secure a smooth sliding and when the hardness is less than A30, a blur is generated on the surface when the seal member is extracted from a molding die.

In order to secure the smooth movement of the spool valve, it is desired that the sliding resistance by the seal member is as small as possible. On the other hand, the seal member should touch with sealed parts even in the case of maximum allowable dimension to prevent the leakage. The leakage of the working fluid can be prevented by the setting as "zero touch" (the seal member just touches the sealed parts without reaction force at the maximum allowable dimension) in consideration of the component tolerance. If the squeeze rate of the seal member is in the range from 0 to 13% in view of the accumulation of tolerances, it is possible to secure the smooth movement of the spool valve and to prevent the leakage.

It may be preferable that a filter is provided on a passage for guiding the working fluid discharged to the discharge area toward one end side of the suction throttle valve. With such a configuration, it is possible to prevent the contaminants that hinder the operation of the valve body from entering from the discharge area.

As described above, according to the present invention, since the suction throttle valve is configured to include a small diameter portion which is slidably housed in a small hole portion formed in the housing, and a large diameter portion and is slidably housed in a large hole portion formed consecutively with the small hole portion while crossing the suction passage, the amount of the refrigerant leaked to the suction passage from the high-pressure side through the clearance around the small diameter portion having a relatively small diameter can be reduced, and even when a seal member is provided on the outer peripheral surface of the small diameter portion in order to prevent the refrigerant leakage in this portion, the seal member will not contact the edge formed in a crossing portion between the suction passage and the large hole portion through which the large diameter portion slides, minimizing the risk that the seal member is cut.

Consequently, when the seal member is provided on the outer peripheral surface of the small diameter portion, the clearance between the small diameter portion and the small hole portion into which the small diameter portion is inserted is sealed by the seal member, and as a result, it is possible to surely prevent the working fluid from leaking from the one end side of the valve body to the suction passage, and it is also possible to decrease or prevent a performance deterioration due to the internal leakage of the pressure.
Consequently, it becomes possible to exactly adjust the passage area of the suction passage based on the difference in pressure between the high-pressure area and the suction area, thereby making it possible to realize both the securing of the cooling capability corresponding to each load condition and the reduction of the pulsation.

Herein, when the rubber hardness of the seal member corresponds to A30 to A50 and the squeeze rate of the seal member is set to 0 to 13%, it is possible to prevent the high-pressure working fluid from flowing to the low-pressure side (suction passage) through the small hole portion, and at the same time, it is possible to secure the smooth movement of the suction throttle valve because the sliding of the small diameter portion is not hindered due to the presence of the seal member.

Moreover, since a filter is provided on the passage for guiding the working fluid discharged to the discharge area toward the one end side of the suction throttle valve so that the penetration of the contaminants from the discharge area is prevented, even when the clearance of the suction throttle valve is set to be small, it is possible to prevent undesired incident that the valve cannot be moved as a result of the contaminants clogging between the suction throttle valve and a hole into which the valve is inserted.

Fig. 1(a) and Fig. 1(b) are diagrams each showing a configuration example of a compressor according to the present invention, Fig. 1(a) being the cross-sectional view and Fig. 1(b) being a view as seen from a line A-A of Fig. 1(a). Fig. 2 is a diagram showing a vicinity of where a valve sliding hole (large hole portion) through which a suction throttle valve of the present application slides and a suction passage cross. Fig. 3(a) and Fig. 3(b) are cross-sectional views each showing a portion where the suction throttle valve cut along a line D-D of Fig. 1(b) is provided, Fig. 3(a) being a view showing a state in a high load and Fig. 3(b) being a view showing a state in a low load. Fig. 4(a), Fig. 4(b), and Fig. 4(c) are diagrams each showing a component configuring the suction throttle valve, Fig. 4(a) being a diagram showing a state where the suction throttle valve is assembled, Fig. 4(b) being a diagram where the suction throttle valve is dissembled, and Fig. 4(c) being an enlarged view showing a small diameter portion of the suction throttle valve. Fig. 5(a) and Fig. 5(b) are graphs showing a characteristic line showing a relationship between a stroke amount from a position at which the suction passage is fully opened and a resistance force (N) while altering the hardness of an O-ring attached to the small diameter portion of the suction throttle valve, Fig. 5(a) being a graph showing a characteristic line showing the resistance force obtained when the piston is stroked from the position at which the suction passage is fully opened up to a 12-mm stroke position, and Fig. 5(b) being a graph showing a characteristic line obtained by enlarging a range from the position at which the suction passage is fully opened to a 1.2-mm stroke position, of the graph showing the characteristic line of Fig. 5(a). Fig. 6 is a graph showing a characteristic line indicating a change in a suction pulsation with respect to a change in difference between a pressure (Pd) of a discharge chamber and a pressure (Ps) of a suction chamber. Fig. 7 is a graph showing a characteristic line obtained by measuring a decrease rate of a cooling capacity when a load is varied, with respect to a case where the clearance between the valve body of the suction throttle valve and the inner wall of the valve sliding hole is set to 30 micron and to a case where the same is set to 15 micron. Fig. 8 is a perspective view showing a procedure in which a conventional spool valve is inserted into a valve sliding hole perpendicular to the suction passage.

Description of Embodiment

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 1(a) and Fig. 1(b) show a variable capacity compressor which is suitable for a refrigerating cycle in which refrigerant is used as working fluid. The compressor is, for example, a clutchlessin-type variable capacity swash plate compressor, and includes a cylinder block 1, a cylinder head 3 assembled on a rear side of the cylinder block 1 via a valve plate 2, and a front housing 5 being assembled to cover a front side of the cylinder block 1 and defining a crank chamber 4 on the front side of the cylinder block 1. The front housing 5, the cylinder block 1, the valve plate 2, and the cylinder head 3, which are fastened together in an axial direction by means of fastening bolts (not shown), configure a housing 6.
A drive shaft 7 placed in the crank chamber 4 is supported in a freely rotatable manner by the front housing 5 and the cylinder block 1 via bearings 8 and 9. The drive shaft 7 is connected to a running engine (not shown) via a belt and a pulley, and rotated as a result of the power of the running engine being conveyed.
The cylinder block 1 is provided with a recess 11 for housing the bearing 9, and a plurality of cylinder bores 12 which are arranged on the circumference around the recess 11 at regular intervals. A single-headed piston 13 is reciprocally slidably inserted into the respective cylinder bores 12.
A thrust flange 14 which rotates integrally with the drive shaft 7 is fixed to the drive shaft 7 in the crank chamber 4. The thrust flange 14 is supported in a freely rotatable manner on the inner wall surface of the front housing 5, which is formed substantially vertical to the drive shaft 7, via a thrust bearing 15. The thrust flange 14 is connected to a swash plate 21 via a link member 20.
The swash plate 21 is tiltably held via a hinge ball 22 disposed on the drive shaft 7, and rotates integrally with the thrust flange 14 in synchronization with the rotation of the thrust flange 14. An engaging portion 13a of the single-headed piston 13 is anchored at the circumferential edge of the swash plate 21 via a pair of shoes 23 disposed at the front and the rear.
Therefore, as the drive shaft 7 rotates, the swash plate 21 also rotates, and the rotation movement of the swash plate 21 is converted into a reciprocal linear movement of the single-headed piston 13 via the shoes 23, thereby altering the volumetric capacity of a compression chamber 25 formed between the single-headed piston 13 and the valve plate 2 in the cylinder bore 12.
In the valve plate 2, a suction hole 31 and a discharge hole 32 which respectively correspond to the cylinder bore 12 are formed. At the cylinder head 3, a suction chamber 33 for housing the working fluid supplied to the compression chamber 25, and a discharge chamber 34 for housing the working fluid discharged from the compression chamber 25 are defined. In this embodiment, the suction chamber 33 is formed at the central portion of the cylinder head 3 and the discharge chamber 34 is formed around the suction chamber 33 in an annular shape.
The suction chamber 33 communicates with a suction inlet 35, which is connected to the low-pressure side (the outlet side of an evaporator) of an external refrigerant circuit via the suction passage 36 extending in a radial direction to penetrate the annular-shaped discharge chamber 34, and the discharge chamber 34 communicates with a discharge outlet (not shown) which is connected to the high-pressure side (the inlet side of a radiator) of the external refrigerant circuit. In addition, the suction chamber 33 is communicable with the compression chamber 25 via the suction hole 31 which is opened and closed by a suction valve 37, and the discharge chamber 34 is communicable with the compression chamber 25 via the discharge hole 32 which is opened and closed by a discharge valve 38.
The discharge capacity of the compressor is determined by the stroke of the piston 13, and the stroke is determined by an inclination angle of the swash plate 21 with respect to a plane perpendicular to the longitudinal axis of the drive shaft 7. That is, the inclination of the swash plate 21 is determined by balancing the differential pressure between the pressure exerting on the front surface of the piston 13, i.e., the pressure of the compression chamber 25 (pressure in the cylinder bore), and the pressure exerting on the rear surface of the piston 13, i.e., the pressure of the crank chamber 4 (the crank chamber pressure), and the biasing force of springs 28 and 29 for biasing a hinge ball 22 in a direction for reducing the piston stroke and in a direction for increasing the piston stroke. As a result, the piston stroke is determined by the above manner, and thus the discharge capacity is determined.
In addition, the cylinder head 3 is provided with an air supply passage (not shown) which communicates with the discharge chamber 34 and the crank chamber 4, and the communication state of the air supply passage is variably controlled by a pressure control valve 40. An air bleeding passage for relieving the working fluid flowing into the crank chamber 4 to the suction chamber 33 is formed by a communication passage 41 formed in the shaft and an orifice hole 42 provided in the valve plate 2 which communicates with the communication passage 41. For this reason, the amount of the working fluid supplied to the crank chamber 4 is adjusted by the pressure control valve 40 which is provided in the midway of the air supply passage, so that the pressure of the crank chamber 4 is controlled to adjust the piston stroke, i.e., the discharge capacity.
Accordingly, as the drive shaft 7 rotates, the swash plate 21 rotates at a predetermined inclination, so that the edge of the swash plate 21 is swung at a predetermined amplitude in the axial direction of the drive shaft 7. As a result, the piston 13 held at the edge of the swash plate 21 reciprocates at a predetermined stroke in the axial direction of the drive shaft 7 to alter the volumetric capacity of the compression chamber 25 which is defined within the cylinder bore 12. At the time of the suction, the refrigerant is suctioned from the suction chamber 33 to the compression chamber 25 via the suction hole 31 which is opened and closed by the suction valve 37. At the time of the compression, the compressed refrigerant is suctioned from the compression chamber 25 to the discharge chamber 34 via the discharge hole 32 which is opened and closed by the discharge valve 38.
In such a compressor, downstream of the suction inlet 35, i.e., in the midway of the suction passage 36 communicating with the suction inlet 35 and the suction chamber 33, a suction throttle valve 60 is provided perpendicular to the suction passage 36, as shown in Fig. 2.
The suction throttle valve 60 includes, as shown in Fig. 3 and Fig. 4, a valve body 61 having a small diameter portion 61a for sensing the working pressure, a large diameter portion 61b for varying the area of the suction passage 36, a stopper portion 61c integrally provided on the small diameter portion side of the large diameter portion 61b, and a relief portion 61d connecting the small diameter portion 61a and the stopper portion 61c. The suction throttle valve 60 slidably houses the valve body 61 in the valve sliding hole 62 which is provided in the cylinder head 3. The small diameter portion 61a, the relief portion 61d, the stopper portion 61c, and the large diameter portion 61b are coaxially integrally formed with one another.
When the valve body 61 is set to the maximum opening position (when the opening end of the large diameter portion 61b shown in Fig. 3(a) is placed at a position to abut a cap 64), the relief portion 61d is placed on the suction passage 36, and thus the area of the suction passage is narrowed. However, since the relief portion 61d is formed to be much smaller than the small diameter portion 61a, it is possible to sufficiently suppress a suction resistance which is caused by narrowing the area of the passage when the valve body 61 is set to the maximum opening position. In addition, as the relief portion 61d is provided, a fitting length between the small diameter portion 61a and the small hole portion 62a can be shortened. Even when contaminants enters into the clearance between the small diameter portion 61a and the small hole portion 62a, the contaminants are made to pass through the shortened fitting length, and thus are easily discharged to the low-pressure side (the suction passage 36) (contaminant discharging ability of the fitting portion is improved).
Further, on the other end side of the suction throttle valve 60, there is provided a spring 63 to bias the valve body 61 toward the minimum opening position. One end side of the spring 63 is built inside the large diameter portion 61b, and the other end side thereof is supported by a cap 64 closing the large hole portion 62b.
The small hole portion 62a communicates with the discharge chamber 34 via a communication passage 50, and thus the working fluid (discharge chamber pressure (Pd)) discharged to the discharge chamber 34 is guided to the one end side (the distal end surface of the small diameter portion 61a) of the suction throttle valve 60. In addition, a space 65 having a diameter slightly larger than the large hole portion 62b is formed between the cap 64 and the large hole portion 62b. The space 65 is connected to the suction chamber 33 via a small hole 66, and the working fluid (suction chamber pressure (Ps)) flowing into the suction chamber 33 is quickly guided to the rear surface of the large diameter portion 61b which is the other end side of the valve body 61.
In addition, in the midway of the communication passage 50 (in this embodiment, at the end of the communication passage 50 opened toward the discharge chamber 34), there is provided a filter 55 so that the penetration of the contaminants from the discharge chamber 34 side is prevented. Furthermore, an O-ring 67 is provided between the outer periphery of the cap 64 and the cylinder head 3, and thus the outer periphery of the cap 64 and the cylinder head 3 are sealed with a high level of airtightness. A counter-spring side end surface of the cap 64 is fixed by a snap ring 68. Accordingly, these parts associated with the suction throttle valve are built inside the cylinder head 3.
In order to prevent the working fluid leaked through the clearance between the outer peripheral surface of the small diameter portion 61a of the valve body and the inner peripheral surface of the small hole portion 62a, a seal member 52 is provided on the outer peripheral surface of the small diameter portion 61a to seal between the outer peripheral surface of the small diameter portion 61a and the inner peripheral surface of the small hole portion 62a (to block the clearance between the outer peripheral surface of the small diameter portion 61a and the inner peripheral surface of the small hole portion 62a).
It is preferable that the seal member 52 completely closes the clearance and does not deteriorate the sliding characteristic of the valve body 61. At the substantially central portion along an axial direction of the outer peripheral surface of the small diameter portion 61a, an annular groove 53 is formed over the whole peripheral portion, and the seal member 52 formed by an O-ring is placed in the annular groove 53.
Fig. 5 shows a measured value of the sliding resistance (resisting force (N)) when the O-ring 52 is attached and the suction throttle valve 60 is moved from the position in a fully opened state. However, as known from the drawing, it is known that as the hardness of the O-ring is decreased, the sliding resistance (static frictional force) when the suction throttle valve 60 starts to move and the sliding resistance (dynamic frictional force) after the suction throttle valve 60 moves are decreased. For this reason, it is desired that the hardness of the O-ring is set to A50 or less.
In addition, Fig. 6 is a diagram showing an example in which the O-rings 52 where the hardness only is differed are attached. For the hardness A60, a state of the suction pulsation according to the movement of the suction throttle valve is measured by altering the differential pressure (Pd-Ps) between the discharge pressure (Pd) and the suction pressure (Ps). Hysteresis characteristics followed by variation in the differential pressure (Pd-Ps) are reduced in the case of the hardness A50 as compared with the case of the hardness A60. It shows that the valve body 61 moves smoothly. It is confirmed that the smaller the hardness, the less the hysteresis characteristics followed by the variation in the differential pressure. Therefore, it is preferable that the hardness is low as much as possible, but it is also confirmed that if the hardness is smaller than A30, then a burr occurs on the surface of the O-ring when it is extracted from a molding die, and it is not suitable for mass production.
For this reason, it is found that if the hardness of the O-ring 52 is set in the range from A30 to A50, it does not affect the productivity while good sliding characteristics are obtained.
In the above-described configuration, since the suction throttle valve 60 is provided perpendicular to the suction passage 36, it is possible to ensure the smooth flow of the suction gas without a change in the flow direction of the suction gas due to collision with the suction throttle valve 60.
In the above-described configuration, the one end side of the suction throttle valve 60 is exerted by the working fluid discharged to the discharge chamber 34. However, since the diameter of the small diameter portion 61a is sufficiently smaller than that of the large diameter portion 61b, the circumferential length of the small diameter portion 61a is short, and the area which causes the leakage due to the difference between the high pressure and the low pressure is small. In addition, since the O-ring is attached on the outer peripheral surface of the small diameter portion, the high pressure working fluid is not leaked from the one end side of the suction throttle valve 60 to the suction passage 36.
Consequently, the spring force of the spring 63 is appropriately set so as to allow the operation of the suction throttle valve 60 to balance with the force caused by the above-described pressure, thereby obtaining the desired operating characteristics.
In the above-described configuration, on the outer peripheral surface of the small diameter portion 61a, there is provided the seal member (O-ring) 52. However, as shown in Fig. 2, since the seal member (O-ring) 52 can be inserted into the small hole portion 62a without contacting the edge E which is formed at the crossing portion between the suction passage 30 and the large hole portion 62b through which the large diameter portion 61b slides, it is not probable that the seal member 52 will be cut.
Further, the above-described embodiment shows a so-called inlet control type in which only the amount of the working fluid supplied to the crank chamber 4 is controlled by the pressure control valve 40 provided in the midway of the air supply passage. However, even when a so-called inlet/outlet control type in which the opening degree of both the air supply passage and the air bleeding passage are controlled by the pressure control valve is employed, the same effect can be obtained.

Reference Sings List

1 cylinder block
2 valve plate
3 cylinder head
5 front housing
6 housing
12 cylinder bore
13 piston
31 suction hole
32 discharge hole
33 suction chamber
34 discharge chamber
35 suction inlet
36 suction passage
37 suction valve
38 discharge valve
53 seal member
55 filter
60 suction throttle valve
61 valve body
61a small diameter portion
61b large diameter portion
61c stopper portion
61d relief portion
62a small hole portion
62b large hole portion
63 spring

Claims

A compressor comprising:
a drive shaft rotatably journaled to a housing;
a plurality of pistons reciprocating in an axial direction by rotation of the drive shaft;
a cylinder block formed with a plurality of cylinder bores through which the plurality of pistons slide and configuring a compression mechanism together with the pistons; and
a cylinder head provided at an end of the cylinder block, which cylinder head includes: a suction chamber, into which working fluid suctioned into the compression mechanism via each suction hole being opened and closed by suction valves provided to correspond to the respective cylinder bores flows from a suction inlet; and a discharge area where the working fluid compressed by the compression mechanism is discharged via each discharge hole being opened and closed by discharge valves provided to correspond to the respective cylinder bores,
the compressor further comprising:
a suction passage that guides refrigerant suctioned from the suction inlet into the suction chamber;
a suction throttle valve provided in a midway of the suction passage and moving in a direction substantially perpendicular to an orientation of the refrigerant flowing through the suction passage, thereby adjusting a passage area of the refrigerant passing through the suction passage; and
a spring that biases the suction throttle valve, wherein
the working fluid discharged to the discharge area is guided toward one end side of the suction throttle valve and the working fluid flowing into the suction chamber is guided toward the other end side of the suction throttle valve,
the suction throttle valve is biased in a direction of enlarging the passage area of the suction passage by the working fluid exerting at one end side of the suction throttle valve, and the suction throttle valve is biased in a direction of reducing the passage area of the suction passage by the working fluid exerting at the other end side of the suction throttle valve and a spring force of the spring, and
the suction throttle valve includes a small diameter portion and a large diameter portion which is formed consecutively with the small diameter portion, and the small diameter portion is slidably housed in a small hole portion which is formed in the housing, and the large diameter portion is slidably housed in a large hole portion which is crossing the suction passage and has an inner diameter which is larger than that of the small hole portion.
The compressor according to claim 1, wherein a seal member is provided on an outer peripheral surface of the small diameter portion to seal between the outer peripheral surface of the small diameter portion and an inner peripheral surface of the small hole portion.
The compressor according to claim 2, wherein the seal member is an O-ring.
The compressor according to claim 2 or 3, wherein hardness of the seal member corresponds to A30 to A50.
The compressor according to claim 2 through 5, wherein a squeeze rate of the seal member is set to 0% to 13%.
The compressor according to claim 1 through 6, wherein the housing comprises: the cylinder block; and a cylinder head assembled to an end of the cylinder block via a valve plate,
wherein the suction throttle valve is provided at the cylinder head and includes a valve body having the small diameter portion which is slidably housed in the small hole portion formed in the cylinder head, the large diameter portion which is formed consecutively with the small hole portion and is slidably housed in the large hole portion crossing the suction passage, a stopper portion which is provided at an end of the large diameter portion at the small diameter portion side to prevent the suction passage from being completely closed by the large diameter portion, and a relief portion which is provided between the small diameter portion and the stopper portion and has a diameter smaller than a diameter of the small diameter portion, and
the working fluid discharged to the discharge area is supplied to a distal end surface of the small diameter portion, the working fluid flowing into the suction chamber is supplied to a rear surface of the large diameter portion, and the valve body is biased toward a side of the small diameter portion by the spring which is provided on the rear surface of the valve body.
The compressor according to claim 1 through 7, wherein a filter is provided on a passage for guiding the working fluid discharged to the discharge area toward one end side of the suction throttle valve.