EP2524138A1

EP2524138A1 - Compressor having suction throttle valve

Info

Publication number: EP2524138A1
Application number: EP11703049A
Authority: EP
Inventors: Hiroyuki Ishida; Norio Suzuki; Nobuhiro Hayasaka
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: WO2011086908A1; JP2011144688A; JP5584476B2

Abstract

Refrigerant compressor has a suction throttle valve (60) provided in the midway of the suction passage (36) for guiding the refrigerant suctioned from the suction inlet (35) to the suction chamber (33). The suction throttle valve (60) adjusts the passage area of the refrigerant passing through the suction passage (36) by moving in a direction substantially perpendicular to the suction passage (36). High pressure oil separated in an oil separator provided in the discharge area is guided to one side (62a) of the suction throttle valve (60). Refrigerant from the suction area is guided to the other end side (62b) of the suction throttle valve (60). Furthermore, a spring (63) biases the suction throttle valve towards the one end side (62a), thereby reducing the passage area of the suction passage (36).

Description

[Title established by the ISA under Rule 37.2] COMPRESSOR HAVING SUCTION THROTTLE VALVE

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 variable capacity swash plate 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. The present invention relates also to an air conditioner system using the same.

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. In this way, the generation of self-induced vibration in the suction valve is prevented.
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. This leads to 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, in the conventional technology, countermeasures as discussed in the below-described Patent Literature 1 and Patent Literature 2 are adopted.
Of the two literatures, the configuration discussed in Patent Literature 1 is such 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, whereby 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.

Further, the configuration discussed in Patent Literature 2 is such that the suction passage is provided with an opening control valve for adjusting the opening degree of the suction passage based on the differential pressure between the suction pressure and the crank chamber pressure, and the crank chamber pressure changing according to a discharge capacity is utilized, whereby the opening degree of the opening control valve is easily made maximum by weakening the influence of the biasing force caused by the spring in a maximum capacity state, and the opening degree of the opening control valve is easily made minimum by strengthening the influence of the biasing force caused by the spring in a small capacity state.

Japanese Unexamined Patent Publication No. 2000-136776 Japanese Unexamined Patent Publication No. 2005-337232

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.

Further, generally, the variable capacity compressor is so structured that an inclination angle of a swash plate is changed based on a difference between a pressure in a cylinder bore exerting on each piston and a crank chamber pressure. The pressure in the cylinder bore is approximately equal to the pressure of the suction chamber when the piston is at a bottom dead center, and gradually rises when the refrigerant gas is compressed by the piston. Then, when the pressure in the cylinder bore exceeds the pressure of the discharge chamber, the valve is opened by a difference in pressure before and after the discharge valve, and the refrigerant gas is discharged to the discharge chamber. That is, the pressure in the cylinder bore changes from a suction pressure to a discharge pressure (strictly speaking, the pressure rises to a slightly higher level due to the delay in opening or the resistance of the discharge valve) while the swash plate makes one rotation, and the pressure always exerts on the piston.

Since the pressure in the cylinder bore exerting on the piston exerts in a direction to increase the inclination angle of the swash plate, even if the difference in pressure between the suction chamber and the crank chamber is the same, the swash plate is so controlled that the inclination angle of the swash plate relatively increases (the discharge capacity is large) under a higher discharge pressure.

Consequently, the opening control valve discussed in Patent Literature 2 is for adjusting the opening degree based on the differential pressure between the suction chamber pressure and the crank chamber pressure irrespective of the discharge pressure, and therefore, when the opening control valve is set to constrict the suction passage when the difference in pressure between the crank chamber and the suction chamber exceeds 0.1 MPa, for example, the following may occur: the opening control valve is not operated until the inclination angle of the swash plate arrives at 30% or less when the pressure of the discharge chamber is low (for example, 0.8 MPa); and the opening control valve starts to constrict the suction passage from point that the inclination angle of the swash plate reaches 70% or less when the pressure of the discharge chamber is high. This means that the suction passage is constricted so that the performance is deteriorated in the high load state where the low pressure pulsation is not generated and thus there is no need of constricting the suction passage, and as a result, even in the opening control valve discussed in Patent Literature 2, it is not possible to achieve both securing of the cooling capability in correspondence with each load condition and the reduction of pulsation.

In either opening control valve, since the opening control valve is provided in an orientation facing the direction of the gas flowing through 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 direction is changed in the right angle direction, thereby blocking the smooth flow of the suction refrigerant.

Further, in the opening control valve discussed in Patent Literature 2, since the pressure guided to one end side of the opening control valve is gas in the crank chamber, there is a drawback that the gas is leaked to a low pressure area side through a clearance between a valve body of the opening control valve and a valve hole into which the valve body is inserted, thereby decreasing the efficiency.
There is a need of setting the clearance between the valve body of the opening control valve and the valve hole into which the valve body is inserted to be smaller in order to suppress the leakage, but contaminants that enter the opening control valve may be trapped in this small clearance and hinder operations of the valve body.

The present invention has been achieved in view of the above circumstance, and a primary object of the present invention is to provide, in a compressor provided with a suction throttle valve capable of decreasing a low pressure pulsation by constricting a suction passage, in an operating range in which the low pressure pulsation easily occurs, a suction throttle valve that prevents the performance from being deteriorated due to the constriction of the suction passage in an operating range in which the low pressure pulsation does not occur.
Another object of the present invention is to suppress a performance deterioration caused due to an internal leakage of pressure guided to the suction throttle valve.
Still another object of the present invention is to prevent an operation of the valve body from being hindered as a result of contaminants being trapped in a clearance between a valve body of a suction throttle valve and a valve hole into which the valve body is inserted.

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 of a plurality of cylinder bores through which the plurality of pistons slide and configuring a compression mechanism together with the pistons; a suction chamber provided at an end of the cylinder block, working fluid being suctioned to the compression mechanism via each suction hole being opened and closed by suction valves provided to correspond to the respective cylinder bores, the working fluid being flowing from a suction inlet; a discharge area into which 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, further comprising: a suction passage that guides refrigerant suctioned from the suction inlet to 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 value, 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 high pressure working fluid exerting on 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 low pressure working fluid and a spring force of the spring exerting at the other end side of the suction throttle valve.

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. Thus, under medium to high load conditions where no suction pulsation is generated and the suction passage needs not to be constricted, the performance is not deteriorated due to the presence of the suction throttle valve.

Further, the passage area of the suction passage is adjusted based on the difference in pressure between the high pressure area and the suction area. As a result, the adjustment eliminates a drawback that the performance is deteriorated as a result of the suction passage being constricted in the high load state where no low pressure pulsation is generated and thus the suction passage does not need to be constricted, thereby achieving both securing of the cooling capability in correspondence with each load condition and the reduction of the pulsation.

A configuration example of the above-described suction throttle valve is such that it is provided in the cylinder head assembled via a valve plate at the end of the cylinder block. A useful configuration of the suction throttle valve is such that the suction throttle valve includes a valve body having a small diameter portion which is slidably housed in a 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 a large hole portion crossing the suction passage, a stopper portion which is provided at an end on the small diameter portion side of the large diameter portion and prevents 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 oil is supplied to a distal end of the small diameter portion, and the working fluid flowing into the suction chamber is supplied to a rear face of the large diameter portion.

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 penetrates, 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 the generation of a suction resistance.

Further, it may be possible that the oil separator for separating the oil from the working fluid compressed by the compression mechanism is provided in the discharge area, and the high pressure oil separated by the oil separator is guided to one end of the suction throttle valve. In such a configuration, the clearance between the valve body of the suction throttle valve and the hole into which the valve body is inserted will be sealed by the oil, and thus it is possible to prevent the gas from being leaked from the one end side of the valve body to the low pressure area side.

Moreover, it may be possible that a filter for guiding the oil separated by the oil separator toward the one end side of the suction throttle valve is provided on the passage. With such a configuration, it is possible to prevent the contaminants that hinder the operation of the valve body from penetrating from the discharge area.

Advantageous Effect of Invention

As described above, according to the present invention, since the suction throttle valve is provided perpendicular to the suction passage, the suction passage will not be constricted resulting from the spring force. Moreover, the flow direction of the suction gas will not be changed due to collision with a suction closing valve. Thus, under medium to high load conditions where no suction pulsation is generated and the suction passage needs not to be constricted, the performance will not be deteriorated due to the presence of the suction throttle valve.
Further, the passage area of the suction passage is adjusted based on the difference in pressure between the high pressure area and the suction area, it is possible to achieve both securing the cooling capability in correspondence with each load condition and the reduction of the pulsation.
Moreover, since the high pressure oil separated by the oil separator is guided to one end of the suction throttle valve, the clearance between the valve body of the suction throttle valve and the hole into which the valve body is inserted will be sealed by the oil. This enables the prevention of the gas from being leaked from the one end side of the valve body toward the low pressure area side.
Moreover, since the filter is provided on the passage for guiding the oil 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 inconvenience that the valve can not be moved as a result of the contaminants being trapped between the suction throttle valve and the 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 a cross-sectional view and Fig. 1(b) being a view as seen from a line A-A of Fig. 1(a). Fig. 2(a) and Fig. 2(b) are diagrams each showing a vicinity where an oil separator of the compressor according to the present invention is provided, Fig. 2(a) being a cross-sectional view obtained by cutting along a B-B line of Fig. 1(b) and Fig. 2(b) being a view as seen from a C-C line of Fig. 2(a). Fig. 3(a) and Fig. 3(b) are cross-sectional views each obtained by cutting along a D-D line of Fig. 1(b), 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 is a diagram showing components configuring a suction throttle valve. Fig. 5 is a graph showing characteristic lines of pressure pulsations, obtained by comparing a compressor without a suction throttle valve, a compressor having a conventional suction throttle valve, and a compressor according to the present invention.

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 clutchless-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 held 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 vertical to 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 discharged 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.
At a rear side end of the cylinder head 3, an oil separator 43 for separating the oil mixed in the working fluid discharged to the discharge chamber 34 is provided, as shown in Fig. 2. The oil separator 43 is configured by stacking a first plate 44, a second plate 45, and a cover member 46 on an upper end surface on the rear side of the cylinder head 3, and so configured that a cylindrical separation space 47 is provided on the second plate 45, one end side of the separation pipe 48 is press-fixed to the first plate 44 in a manner to protrude to the separation space 47, and the other end side of the separation pipe 48 is substantially coaxial to the separation space 47.
The discharge chamber 34 communicates with the separation space 47 through a guide passage 51 formed by a through hole 49 formed in the cylinder head 3 and a through hole 50 formed on the first plate 44 and a passage groove 52 looking on the guide passage 51 and being formed on a front-side end surface of the second plate 45.
The passage groove 52 is formed to be oriented toward a tangent direction of the separation space 47, and the refrigerant gas introduced to the separation space 47 through the passage groove 52 circulates around the separation pipe 48 by the refrigerant gas's own force. The refrigerant gas from which the oil is separated by the centrifugal action is guided through the separation pipe 48 disposed at the center of the separation space 47 to a sub chamber 53 provided in the cylinder head 3.
Then, the gas guided to the sub chamber 53 passes through the discharge passage 54 to be guided to the front side of the cylinder head 3, guided vie a through hole of the valve plate 2 to a muffler chamber provided at the upper portion of the cylinder block 1, and discharged to an external refrigerant circuit from a discharge outlet (not shown). Therefore, by an oil separator capability realized by the oil separator 43, the circulation of the oil through the refrigerant circuit, which hinders a heat exchange, is suppressed.
The oil separated in the separation space 47 passes through a groove 55 provided on the rear-side end surface of the second plate 45 to be guided to an oil retaining chamber 56 defined by the rear-side end surface of the cylinder head 3, the first plate 44, and the second plate 45. At a lower portion of the oil retaining chamber 56, a discharge hole 57 is provided, and the discharge hole 57 communicates with the suction chamber 33. At an entry of the discharge hole 57, an orifice 58 is provided, and the high pressure oil retained in the oil retaining chamber 56 is depressurized by the orifice 58 and returned to the suction chamber 33.
In such a compressor, downstream of the suction inlet 35, i.e., in the midway of the suction passage 36 communicating 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. 3.
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 set to a position to abut a cap 64), the relief portion 61d is placed on the suction passage 26, 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.
When the fitting length is short, a high-pressure seal length exerting on one end of the small diameter portion 61a is shortened, when the valve body 61 is set to the maximum opening position, however, the small diameter portion 61a is fitted only slightly into the small hole portion 62a in the first place, and thus, the valve body 61 does not contribute to the sealing between the high pressure and the low pressure. When the valve is set to the minimum opening position, the pressure exerting on one end of the valve body 61 is relatively low, and thus, the leakage is further minimized. Thus, the provision of the relief portion 61d serves to reduce the passage resistance of the suction passage 26 and enhance a contaminant discharging ability in the fitting portion of the small diameter portion while no or little influence is applied on the leakage of the small diameter portion 61a.
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 the cap 64.
Between the cap 64 and the large hole portion 62b, a space 65 having a hole diameter slightly larger than that of the large hole portion 62b is provided. The suction chamber 33 and the space 65 are connected by a small hole 66, and because of this, the suction chamber pressure is promptly guided to the large diameter portion 61b which is the other end side of the valve body 61.
An O-ring 67 is provided between the outer periphery of the cap 64 and the cylinder head 3, the end surface of a counter-spring side is sealed with a snap ring 68, and the components associated with the suction throttle valve are built inside the cylinder head 3.
At a lower portion of the oil retaining chamber 56, an oil guide hole 70 for guiding high-pressure oil to one end of the suction throttle valve 60 is provided. In the figure, the position of the oil guide hole 70 is shown on the same section view of the discharge hole 57 for the sake of convenience. However, the oil guide hole 70 is provided at a slightly lower position, and thus, even if almost all the oil of the oil retaining chamber 56 is discharged to the suction chamber 33 from the discharge hole 57, the oil is always secured because the oil guide hole 70 is at a lower position.
Further, at the entry of the oil guide hole 70, a filter 71 is provided so that the contaminants are removed from the oil guided to the suction throttle valve 60.
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.
As described above, the discharge pressure (high pressure oil separated by the oil separator 43) is exerted on the small diameter portion 61a which is one end side of the suction throttle valve 60 and the suction chamber pressure is exerted on the large diameter portion 61b which is the other end side thereof while the suction pressure is also exerted on a surface opposite to the other end side of the large diameter portion 61b (i.e., the suction passage side). As a result, the force generated by the pressure exerted on the suction throttle valve 60 is expressed by:
(area of small diameter portion)*(discharge pressure - suction pressure).
Consequently, 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 operation.
According to the results obtained by the studies carried out by the present inventors, it was learned that when the variable capacity compressor was operated under various heat load conditions, if the difference in pressure between the discharge pressure and the suction chamber was 0.6 MPa or less, the suction pulsation was detected, and if the difference in pressure was 1.0 MPa or more, the suction pulsation was not generated.
Based on these findings, the variable capacity compressor was placed under the following conditions: the suction throttle valve was set to the fully opened position during Pd-Ps>1.0 MPa (the area of suction passage: 184 mm², which was, as described above, obtained by subtracting the projection area of the relief portion of the suction throttle valve from the area of the suction passage diameter); in a zone of Pd-Ps=0.6 to 1.0 MPa, the passage area was gradually decreased along with the decrease in the difference in pressure; and during Pd-Ps<=0.6 MPa, the valve was set to the minimum opening position. The comparison results of the suction pulsation obtained thereby are shown in Fig. 5. As can be seen from the results, when the suction throttle valve 60 according to the present invention was used, the effective pulsation reduction was possible even in a low rotation area (low load area) in which the low pressure pulsation was easily generated, and the cooling capability was secured corresponding to each load condition and the pulsation was reduced at the same time.
In the above-described configuration, the high pressure oil guided from the oil retaining chamber 56 is exerted on the end surface of the small diameter portion 61a which is one end side of the suction throttle valve 60, however, the diameter of the small diameter portion 61a is sufficiently small relative to the suction passage 36, and the circumferential length of the small diameter portion 61a is short and the area in which the leakage between the high pressure and low pressure may occur is small. Since the oil, rather than the gas, is guided to one end side of the suction throttle valve 60, the seal effect by the oil film is obtained, and thus, even when there is a variance in the clearance between the small diameter portion 61a and the small hole portion 62a, it is still possible to remarkably decrease the leakage.
It should be noted that in the above-described embodiment, the oil separated by the oil separator 43 is returned via the orifice 58 to the suction chamber 33, but instead of this configuration, the oil may be guided to a discharge pressure guide hole of the pressure control valve 40. According to this structure, since the separated oil is guided via the pressure control valve 40 to the crank chamber 4, it is possible to supply a plenty of amount of oil at a sliding position of the compressor. As a result, unlike the above-described embodiment, the supply of gas to the low pressure area (the crank chamber and the suction chamber) from the high pressure area is limited to one system, and thus, it is possible to decrease an amount of refrigerant (not contributing to the refrigerating capability) to be circulated in the compressor.
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, a so-called inlet/outlet control type in which the opening degree of both the air supply passage and the opening degree of air bleeding passage are controlled by the pressure control valve may be employed.
Moreover, the above-described embodiment shows the configuration example in which the oil separated by the oil separator 43 is guided to one end side of the suction throttle valve 60. However, even when the working fluid in the discharge area (gas mixed with the oil) is directly guided to the one end side of the suction throttle valve 60 while the oil separator 43 is not provided, 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
43 oil separator
60 suction throttle valve
61a small diameter portion
61b large diameter portion
61c stopper portion
61d relief portion
62a small hole portion
62b large hole portion
63 spring
70 oil guide hole
71 filter

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 of a plurality of cylinder bores along which the plurality of pistons slide and configuring a compression mechanism together with the pistons;
a suction chamber provided at an end of the cylinder block, working fluid being suctioned to the compression mechanism via each suction hole being opened and closed by suction valves provided to correspond to the respective cylinder bores,
the working fluid being flowing from a suction inlet;
a discharge area into which 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, 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 value, 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 on 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 and a spring force of the spring exerting on the other end side of the suction throttle valve.
The compressor according to claim 1, wherein
the suction throttle valve is provided in the cylinder head assembled via a valve plate at the end of the cylinder block,
the suction throttle valve includes a valve body having a small diameter portion which is slidably housed in a 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 a large hole portion crossing the suction passage, a stopper portion which is provided at an end on the small diameter portion side of the large diameter portion and prevents 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 of the small diameter portion, and the working fluid flowing into the suction chamber is supplied to a rear face of the large diameter portion.
The compressor according to claim 1 or 2 comprising an oil separator for separating oil from working fluid compressed by the compressor, the oil separator being arranged in the discharge area, wherein
the working fluid guided to one end side of the suction throttle valve is the oil separated by the oil separator.
The compressor according to claim 3, wherein
a filter is provided on a passage for guiding the oil separated by the oil separator to one end side of the suction throttle valve.