CONTROL VALVE OF SCROLL COMPRESSOR

Abstract

 A control valve (1) is to be applied to a scroll compressor including a suction chamber, a discharge chamber, and a back pressure chamber, to control a pressure in the back pressure chamber. The control valve (1) includes a valve section that adjusts a flow of fluid introduced from the discharge chamber into the back pressure chamber or fluid delivered from the back pressure chamber into the suction chamber. The control valve (1) has valve opening characteristics that change depending on the flow rate of the fluid flowing through the valve section.

Description

[0001] The present invention relates to a control valve of a scroll compressor and, in particular, to a structure for controlling back pressure for pressing a fixed scroll and a movable scroll of a scroll compressor against each other.

[0002] A scroll compressor including a fixed scroll and a movable scroll is known as an example of a motor compressor (refer to JP 2018-150835 A). In the compressor, fluid introduced into a suction chamber is guided into a compression chamber formed between the scrolls, and the movable scroll is then rotated. By gradually reducing the volume of the compression chamber in this manner, the fluid can be compressed. The compressed fluid is led out from the discharge chamber. A back pressure chamber is formed on a side opposite the fixed scroll with respect to the movable scroll. The pressure in the back pressure chamber (also referred to as "back pressure") presses the scrolls against each other, which ensures the compression performance. Thus, this prevents poor compression due to separation of the scrolls caused by increased pressures during compressing operation.

[0003] In order to increase the responsiveness of control on the back pressure, such a compressor typically uses the high pressure in the discharge chamber (also referred to as "discharge pressure") to increase the back pressure. If the back pressure becomes higher than necessary, however, the frictional resistance between the scrolls increases, and the power loss increases. A control valve is therefore provided between the discharge chamber and the back pressure chamber to control the back pressure depending on the discharge pressure. Thus, such control characteristics in which the discharge pressure and the back pressure are substantially proportional to each other are achieved (refer to JP 2018-536110 A).

[0004] In the control valve of JP 2018-536110 A, a valve hole communicating with the discharge chamber, a first pressure chamber communicating with the back pressure chamber, a suction pressure chamber communicating with the suction chamber, a reference pressure chamber into which air is introduced at a reference pressure, and a second pressure chamber communicating with the back pressure chamber are arranged in this order from one end side of a body. A movable member that can shift integrally with the valve element along the axis of the body is provided. The movable member is constituted by three segments (first to third segments) connected in series. The first segment slidably extends through a partition in the body, and a valve element is formed at a leading end of the first segment. The second segment and the third segment each have a rubber at its periphery and are connected with an inner face of the body at the rubbers in a fluid seal manner.

[0005] The first pressure chamber is formed between the valve hole and the partition, and the suction pressure chamber is formed between the partition and the second segment. The reference pressure chamber is formed between the second segment and the third segment, and the second pressure chamber is formed on a side opposite the reference pressure chamber with respect to the third segment. The reference pressure chamber is open to the atmosphere. Such a structure enables the second segment to sense the suction pressure in the compressor to control the back pressure. In other words, it is possible to make the back pressure closer to a required value depending on variation of the suction pressure while maintaining control characteristics indicating variation of the back pressure depending on the discharge pressure.

Related Art List

[0006] 

(1) JP 2018-150835 A

(2) JP 2018-536110 A

[0007] In order to fix the rubbers of the segments to the inner face of the body, however, a troublesome process is required. Furthermore, if refrigerant in the suction pressure chamber of the second pressure chamber leaks into the reference pressure chamber owing to a defect or the quality of the rubber, the refrigerant may be released to the atmosphere. The inventors have uniquely devised a structure of a control valve and have thus reached an idea that the aforementioned demand can be met without using the structure of JP 2018-536110 A in which the fluid seal technique is used.

[0008] The present invention has been made in view of such circumstances, and one object thereof is to improve suction-pressure dependence while maintaining control characteristics of back pressure control depending on discharge pressure in a scroll compressor.

[0009] An aspect of the present invention is a control valve to be applied to a scroll compressor including and a suction chamber, a discharge chamber, and a back pressure chamber, for controlling a pressure in the back pressure chamber. The control valve includes a valve section for adjusting a flow of fluid introduced from the discharge chamber into the back pressure chamber or fluid delivered from the back pressure chamber into the suction chamber. A change in valve opening characteristics is dependent on a flow rate of the fluid flowing through the valve section.

[0010] According to this aspect, the valve opening characteristics of the control valve change depending on the flow rate of the fluid flowing through the valve section. Thus, in back pressure control of the compressor, the valve section autonomously adjusts its opening degree, which enables the suction-pressure dependence to increase while the discharge-pressure dependence is maintained.

[0011] Another aspect of the present invention is a scroll compressor in which a fixed scroll and a movable scroll are pressed against each other by a pressure in a back pressure chamber, and fluid introduced into a suction chamber is compressed in a compression chamber formed between the scrolls and then discharged from a discharge chamber. The compressor includes a control valve for controlling the pressure in the back pressure chamber. The control valve includes a valve section that adjusts a flow of fluid introduced from the discharge chamber into the back pressure chamber or fluid delivered from the back pressure chamber into the suction chamber. The valve opening characteristics change depending on the flow rate of the fluid flowing through the valve section.

[0012] According to this aspect, the control valve for controlling the back pressure in the compressor is provided, and the control valve have valve opening characteristics that change depending on the flow rate of the fluid flowing through the valve section. Thus, in back pressure control of the compressor, the valve section of the control valve autonomously adjusts its opening degree, which enables the suction-pressure dependence to increase while the discharge-pressure dependence is maintained.

FIG. 1 schematically illustrates a refrigeration cycle including a compressor according to an embodiment.

FIG. 2 is a cross-sectional view taken along arrows A-A in FIG. 1.

FIG. 3 is a cross-sectional view of a structure of a control valve.

FIGS. 4A and 4B illustrate differences in effects depending on whether or not intermediate pressure is received.

FIG. 5 is a graph showing differences in effects depending on whether or not the intermediate pressure is received.

FIG. 6 is a cross-sectional view illustrating a structure of a control valve according to a first modification.

FIG. 7 is a partially-enlarged cross-sectional view illustrating structures of a compressor and a control valve according to a second modification.

FIG. 8 is a cross-sectional view illustrating a structure of a control valve according to a third modification.

FIG. 9 is a cross-sectional view illustrating a structure of a control valve according to a fourth modification.

FIG. 10 is a cross-sectional view illustrating a structure of a compressor according to the fourth modification.

FIG. 11 is a cross-sectional view illustrating a structure of a compressor according to a fifth modification.

FIG. 12 is a cross-sectional view illustrating a structure of a control valve according to the fifth modification.

FIG. 13 is a cross-sectional view illustrating a structure of a control valve according to a sixth modification.

[0013] An embodiment of the invention will now be described. The description is not intended to limit the scope of the present invention, but to exemplify the invention.

[0014] The embodiment of the present invention will now be described in detail with reference to the drawings. In the description below, for convenience of description, the positional relationship in each structure may be expressed with reference to how the structure is depicted in the drawings. In the following embodiment and modifications thereof, components that are substantially the same will be designated by the same reference numerals and redundant description thereof may be omitted as appropriate.

[0015] FIG. 1 schematically illustrates a refrigeration cycle including a compressor according to the embodiment. FIG. 2 is a cross-sectional view taken along arrows A-A in FIG. 1.
As illustrated in FIG. 1, a compressor 100 is a scroll compressor driven by a motor and installed in a refrigeration cycle of an automotive air conditioner. The air conditioner of the present embodiment includes a so-called supercritical refrigeration cycle in which carbon dioxide is used as refrigerant and which operates at high pressure. The air conditioner includes a compressor 100 that compresses gaseous refrigerant circulating through the refrigeration cycle, a gas cooler 102 serving as an external heat exchanger that cools the compressed high-temperature and high-pressure gaseous refrigerant, an expander 104 that adiabatically expands the cooled refrigerant to reduce the pressure thereof, an evaporator 106 evaporates the expanded refrigerant to remove the evaporative latent heat to cool the air in the vehicle interior, and a receiver 108 that separates the evaporated refrigerant into gas refrigerant and liquid refrigerant and then returns the thus separated gaseous carbon dioxide to the compressor 100.

[0016] The compressor 100 includes, inside its housing 110, a scroll unit 112, a motor 114 for driving the scroll unit 112, an inverter 116 for controlling the rotation speed of the motor 114, and a control valve 1 for controlling the back pressure of the scroll unit 112. The housing 110 is constituted by an assembly of a center housing 118, a front housing 120 connected to a front end sided of the center housing 118, and a rear housing 122 connected to a rear end side of the center housing 118.

[0017] The scroll unit 112 is located inside the center housing 118. The scroll unit 112 is constituted by a fixed scroll 124 and a movable scroll 126 that axially face each other. The fixed scroll 124 includes a stepped disc-shaped base 128, and a wrap 130 that spirally stands on a front face of the base 128. The base 128 is fixed to the housing 110 in a state in which the base is held between the center housing 118 and the rear housing 122. The base 128 generally closes a rear end of the center housing 118. A discharge chamber 132 is formed between the base 128 and the rear housing 122. A discharge passage 134 is formed to axially pass through the middle of the base 128. A relief valve 136 is provided on a rear face side of the base 128. The relief valve 136 is a one-way valve that opens and closes an open end of the discharge passage 134 on the discharge chamber 132 side.

[0018] The movable scroll 126 includes a stepped disc-shaped base 138, and a wrap 140 that spirally stands on a rear face of the base 138. The wrap 140 engages with the wrap 130 of the fixed scroll 124, and a compression chamber 142 is formed therebetween. A middle portion of a front face of the movable scroll 126 protrudes in a circular boss shape, and a bush 144 is rotatably fitted into the circular boss-shaped portion. The bush 144 is connected with a rotating shaft 146 of the motor 114.

[0019] A middle portion of a front wall 148 of the center housing 118 sticks out toward the front housing 120, and a bearing 150 is provided inside the front wall 148. An insertion hole 152 is formed at the middle of a leading end of the front wall 148, and the rotating shaft 146 extends through the insertion hole 152 and the bearing 150. An annular thrust plate 154 is arranged between the front wall 148 and the movable scroll 126. The front wall 148 receives thrust force from the movable scroll 126 via the thrust plate. A space surrounded by the front wall 148 and the movable scroll 126 serves as a back pressure chamber 156. The fixed scroll 124 and the movable scroll 126 are pressed against each other by the pressure (back pressure Pb) in the back pressure chamber 156.

[0020] A seal ring 158 is provided between the front wall 148 and the thrust plate 154, and a seal ring 160 is provided between the movable scroll 126 and the thrust plate 154. In addition, a sealing member 162 (lip seal) is provided between the insertion hole 152 and the bearing 150. Such a structure achieves good sealing performance of the back pressure chamber 156.

[0021] The front housing 120 is separated into a suction chamber 166 and a control chamber 168 by a partition 164. The motor 114 is accommodated in the suction chamber 166, and the inverter 116 is accommodated in the control chamber 168. The control chamber 168 is located at a front end part of the housing 110, and closed by a cover 170. A support 165 having a circular boss shape protrudes from a middle portion of a rear face of the partition 164, and a bearing 167 (plain bearing) is press-fitted into the support 165.

[0022] The motor 114 is a three-phase alternating-current (AC) motor, for example, and includes the rotating shaft 146, a rotor 172 provided integrally with the rotating shaft 146, and a stator 174 fixed to the front housing 120. For example, direct current supplied from an on-board battery, which is not illustrated, is converted into alternating current by the inverter 116, which is then supplied to the motor 114.

[0023] A front end side of the rotating shaft 146 is supported by the bearing 167, and a rear end side thereof is supported by the bearing 150. An eccentric connecting portion 178 having a columnar shape protrudes from a rear end of the rotating shaft 146 at an eccentric position with respect to the central axis of the rotating shaft 146. The eccentric connecting portion 178 is connected with the movable scroll 126 with the bush 144 therebetween. A balance weight 180 is integrally provided on the rear end portion of the rotating shaft 146. The balance weight 180 cancels out centrifugal force caused by revolution of the movable scroll 126.

[0024] An inlet passage 182 for introducing refrigerant into the suction chamber 166 is formed at the front housing 120. A communication passage 186 through which a suction pressure space 184 leading to an inlet of the compression chamber 142 communicates with the suction chamber 166 is formed in the center housing 118. Note that the suction pressure space 184 is a space filled with the suction pressure Ps in the compressor 100 and can therefore be regarded as part of the suction chamber 166.

[0025] The discharge chamber 132 and a mounting hole 187 are formed in the rear housing 122. The control valve 1 is mounted by being inserted into the mounting hole 187. An outlet passage 190 for delivering discharged refrigerant from the discharge chamber 132 toward the gas cooler 102 is also formed at the rear housing 122.

[0026] Furthermore, a communication passage 191 through which the discharge chamber 132 and the mounting hole 187 communicate, a communication passage 193 through which the back pressure chamber 156 and the mounting hole 187 communicate, and a communication passage 195 through which the suction pressure space 184 and the mounting hole 187 communicate are also formed in the rear housing 122. As will be described later, the control valve 1 has a discharge chamber communication port, a back pressure chamber communication port, and a suction chamber communication port. The communication passage 191 communicates with the discharge chamber communication port, the communication passage 193 communicates with the back pressure chamber communication port, and the communication passage 195 communicates with the suction chamber communication port. The communication passage 193 communicates with the back pressure chamber 156 through a communication passage 197 formed in the center housing 118. The communication passage 195 communicates with the suction pressure space 184 through a communication hole 199 formed in the base 128. In addition, a communication passage 200 through which an open end of the mounting hole 187 and the back pressure chamber communication port communicate is formed.

[0027] In the compressor 100 having the above-described structure, refrigerant at the suction pressure Ps introduced into the suction chamber 166 through the inlet passage 182 is introduced into the compression chamber 142 of the scroll unit 112. As illustrated in FIG. 2, the fixed scroll 124 and the movable scroll 126 are engaged with each other, and compression chambers 142a and 142b, which will be collectively referred to as the "compression chamber 142", are formed between the wraps 130 and 140.

[0028] With swirling movement of the movable scroll 126, the refrigerant is sucked into the suction pressure space 184 and delivered to an inlet of the compression chamber 142. As the movable scroll 126 turns, each compression chamber 142 moves from the outer circumferential side toward the center with its capacity decreasing. In this process, the refrigerant in the compression chamber 142 is gradually compressed into high-temperature and high-pressure refrigerant. When the compression chamber 142 reaches a position at which the compression chamber 142 communicates with the discharge passage 134, the refrigerant is discharged as refrigerant at the discharge pressure Pd to the discharge chamber 132. The discharged refrigerant is delivered through the outlet passage 190 toward the gas cooler 102. Part of the discharged refrigerant is introduced into the back pressure chamber 156 via the control valve 1 and used for back pressure control. Specifically, the control valve 1 functions as a control valve for so-called "inflow control" for controlling the flow rate of refrigerant introduced from the discharge chamber 132 into the back pressure chamber 156. This enables adjustment of the pressure (back pressure Pb) in the back pressure chamber 156.

[0029] FIG. 3 is a cross-sectional view of a structure of the control valve 1.
The control valve 1 has a body 5 having a stepped cylindrical shape. The body 5 has ports 10, 12, and 14 arranged in this order from an upper end thereof. The port 10 functions as the "discharge chamber communication port", which communicates with the discharge chamber 132 through the communication passage 191 described above (see FIG. 1). The port 12 functions as the "back pressure chamber communication port", which communicates with the back pressure chamber 156 through the communication passages 193 and 197 described above. The port 14 functions as the "suction chamber communication port", which communicates with the suction pressure space 184 through the communication passages 195 and 199 described above.

[0030] A partition 16 and a partition 18 are formed to axially divide an upper partial area in the body 5. Furthermore, a stopping member 19 is provided to axially divide a lower area. A discharge pressure chamber 20 is formed on an upper side of the partition 16, and a first pressure chamber 22 is formed on a lower side thereof. The first pressure chamber 22 functions as a "control pressure chamber".

[0031] A valve hole 24 is formed to axially pass through the center of the partition 16. The discharge pressure chamber 20 and the first pressure chamber 22 communicate with each other through the valve hole 24. A valve seat 26 is formed at an open end of the valve hole 24 on the side of the first pressure chamber 22. The discharge pressure chamber 20 communicates with the discharge chamber 132 through the port 10. The first pressure chamber 22 communicates with the back pressure chamber 156 through the port 12. A discharge pressure Pd introduced into the discharge pressure chamber 20 changes to a back pressure Pb as a result of passing through a valve section (valve hole 24), and then delivered from the first pressure chamber 22 toward the back pressure chamber 156.

[0032] A guiding hole 32 is formed to axially pass through the center of the partition 18. An elongated valve drive member 34 axially extends through the guiding hole 32. A lower part of the body 5 (on a lower side of the port 14) also has a function as a guiding hole 33. The valve drive member 34 has a stepped columnar shape with an upper part slidably supported in the guiding hole 32 and a lower part slidably supported in the guiding hole 33. The valve drive member 34 has a valve element 36 having a tapered shape at one end (upper end) thereof, and an enlarged-diameter part 38 at the lower part. The enlarged-diameter part 38 slides along the guiding hole 33. The valve element 36 shifts integrally with the valve drive member 34 and thus moves toward and away from the valve hole 24 to adjust the opening degree of the valve section. The stopping member 19 stops the enlarged-diameter part 38 to restrict the movement of the valve drive member 34 in the valve opening direction.

[0033] A suction pressure chamber 28 is formed between the partition 18 and the enlarged-diameter part 38. The suction pressure chamber 28 communicates with the suction chamber 166 through the port 14, and a suction pressure Ps is introduced into the suction pressure chamber 28. A spring 40 (biasing member) that biases the valve drive member 34 in the valve opening direction is provided between an internal bottom surface of the body 5 and the enlarged-diameter part 38 in the suction pressure chamber 28.

[0034] A second pressure chamber 29 is formed between the enlarged-diameter part 38 and the stopping member 19 inside the body 5, and a third pressure chamber 30 is formed on a lower side of the stopping member 19. Specifically, the enlarged-diameter part 38 is arranged in the body 5 to separate the suction pressure chamber 28 from the second pressure chamber 29. The stopping member 19 is arranged in the body 5 to separate the second pressure chamber 29 from the third pressure chamber 30. The second pressure chamber 29 functions as an "intermediate pressure chamber".

[0035] A communication hole 60 that axially passes through the middle of the stopping member 19 is formed. A lower end of the communication hole 60 is reduced in diameter to form a throttle 62 (orifice). In addition, a communication hole 64 that passes through a portion near an outer edge of the enlarged-diameter part 38 in parallel with the axis is formed. A lower end of the communication hole 64 is reduced in diameter to form a throttle 66 (orifice). The throttle 62 functions as a "first throttle" that is an inlet of the refrigerant from the third pressure chamber 30 into the second pressure chamber 29. The throttle 66 functions as a "second throttle" that is an outlet of the fluid from the second pressure chamber 29 into the suction pressure chamber 28.

[0036] A plurality of slits 31 that are open radially are formed at a lower end of the body 5. The third pressure chamber 30 communicates, through the slits 31 and the communication passage 200, with a space (a space defined by an O ring 50 and an O ring 52) to which the port 12 is open in the mounting hole 187 (see FIG. 1). The back pressure Pb is thus also introduced into the third pressure chamber 30.

[0037] In the present embodiment, a clearance between the valve drive member 34 and the guiding hole 32 is set to be narrow, which achieves a so-called clearance seal. This prevents leakage of refrigerant from the first pressure chamber 22 to the suction pressure chamber 28. In addition, a clearance between the valve drive member 34 and the guiding hole 33 is also set to be narrow, which achieves a clearance seal. This prevents leakage of refrigerant from the second pressure chamber 29 to the suction pressure chamber 28. Alternatively, in a modification, a sealing member such as an O ring may be provided at least either between valve drive member 34 and guiding hole 32 or between the valve drive member 34 and the guiding hole 33 to prevent flow of refrigerant.

[0038] The refrigerant at the back pressure Pb introduced into the third pressure chamber 30 is reduced in pressure by passing through the throttle 62, and is introduced into the second pressure chamber 29 through the communication hole 60. The refrigerant in the second pressure chamber 29 is delivered to the suction pressure chamber 28 through the communication hole 64. This refrigerant is reduced in pressure by passing through the throttle 66. As a result, the second pressure chamber 29 is filled with an intermediate pressure Pb' that is higher than the suction pressure Ps and lower than the back pressure Pb (Ps<Pb'<Pb).

[0039] The intermediate pressure Pb' is a pressure higher than the suction pressure Ps, lower than the discharge pressure Pd and different from the back pressure Pb. The enlarged-diameter part 38 separates the suction pressure chamber 28 from the second pressure chamber 29, is slidably supported in the body 5, and functions as a "pressure-receiving part" that receives a differential pressure (Pb'-Ps) between the intermediate pressure Pb' and the suction pressure Ps. The valve drive member 34 moves in response to the differential pressure (Pb'-Ps) received by the enlarged-diameter part 38.

[0040] A filter member 42 for preventing entry of foreign materials through the port 10 is fitted into an upper end opening of the body 5. Refrigerant discharged from the compressor 100 may contain foreign materials such as metal powder, and the filter member 42 prevents or reduces entry of such foreign materials into the control valve 1. The filter member 42 has a filter 44 having a bottomed cylindrical shape, and a metal plate 46 having a ring shape that reinforces the open end of the filter 44. The filter 44 is made of a metal mesh. The filter member 42 with its bottom side up is fixed in such a manner that the metal plate 46 is press-fitted into the body 5. The filter member 42 is mounted inside the body 5 as illustrated in FIG. 1, which prevents the filter member 42 from being deformed by contact with external structures.

[0041] A filter member 43 having a cylindrical shape is also mounted at the port 12. The filter member 43 includes a mesh for preventing entry of foreign materials into the body 5.

[0042] A plurality of seal rings are provided on the outer circumferential face of the control valve 1 to achieve sealing between the ports when the control valve 1 is mounted in the mounting hole 187. Specifically, on the outer circumferential face of the body 5, an O ring 50 is fitted on an upper side of the port 12, an O ring 52 is fitted between the port 12 and the port 14, and an O ring 54 is fitted on a lower side of the port 14 (see FIG. 1).

[0043] In the structure described above, the cross-sectional area C of the guiding hole 33 is sufficiently larger than the difference between the cross-sectional area B of the guiding hole 32 and the cross-sectional area A of the valve hole 24 (C>B-A). Thus, a force in the valve closing direction caused by the intermediate pressure Pb', which is greater than a force in the valve opening direction caused by the back pressure Pb, acts on the valve drive member 34. On the valve drive member 34, the intermediate pressure Pb' acts in the valve closing direction and the suction pressure Ps and the discharge pressure Pd acts in the valve opening direction. The control valve 1 controls the back pressure Pb while changing the opening degree of the valve section depending on the suction pressure Ps, the discharge pressure Pd, and the intermediate pressure Pb'.

[0044] Next, operations for controlling the compressor 100 will be explained.

[0045] When the compressor 100 is driven, the movable scroll 126 turns (revolves) about the axis of the fixed scroll 124. The revolution of the movable scroll 126 causes the compression chamber 142 between the scrolls to move from the outer side toward the center while decreasing its volume. In this process, the pressure of the refrigerant increases from the suction pressure Ps to the discharge pressure Pd. The discharged refrigerant circulates in the refrigeration cycle for air conditioning performed by an air conditioner for a vehicle.

[0046] In this process, part of the discharged refrigerant is supplied through the port 10 of the control valve 1 to control the back pressure Pb of the compressor 100. In the control valve 1, the valve element 36 is maintained at a valve lifted position at which the force in the valve opening direction caused by the discharge pressure Pd, the force in the valve opening direction caused by the suction pressure Ps, the force in the valve opening direction caused by the back pressure Pb, the force in the valve closing direction caused by the intermediate pressure Pb', and the force in the valve opening direction caused by the spring 40 are balanced.

[0047] When either of the discharge pressure Pd and the suction pressure Ps is increased in the process of control of the back pressure Pb, the force acting on the valve element 36 in the valve opening direction increases. Thus, the back pressure Pb, which is the pressure before being reduced to the intermediate pressure Pb', also increases to increase the force in the valve closing direction that balances the load on the valve element 36 in the valve opening direction. Thus, the control characteristics (also referred to as "discharge-pressure dependence") in which the back pressure Pb proportionally increases with the increase in the discharge pressure Pd and the control characteristics (also referred to as "suction-pressure dependence") in which the back pressure Pb increases with the increase in the suction pressure Ps are achieved.

[0048] FIGS. 4A, 4B, and 5 illustrate differences in effects depending on whether or not the intermediate pressure is received. FIG. 4A illustrates a structure of the present embodiment in which the intermediate pressure Pb' is received. FIG. 4B illustrates a structure of a comparative example in which the intermediate pressure Pb' is not received. The comparative example is different from the present embodiment in that the second pressure chamber 229 has a single outlet/inlet and that no throttle is formed. The back pressure Pb is introduced into the second pressure chamber 229 through a communication hole 260.

[0049] FIG. 5 shows the control characteristics (the discharge-pressure dependence and the suction-pressure dependence) in each of the present embodiment and the comparative example. The horizontal axis represents the discharge pressure Pd, and the vertical axis represents the back pressure Pb. FIG. 5 shows changes in the discharge-pressure dependence when the suction pressure Ps is changed from Ps1 to Ps3 (Ps1 < Ps2 < Ps3). Solid lines represent the control characteristics in the present embodiment, and broken lines represent the control characteristics in the comparative example.

[0050] According to the present embodiment, the valve opening characteristics of the control valve change depending on the flow rate of fluid flowing through the valve section. The intermediate pressure Pb' changes depending on the flow rate of refrigerant flowing through the throttles 62 and 66. As the discharge pressure Pd becomes higher and the flow rate increases, the back pressure Pb also becomes higher and, as a result, a pressure loss at the throttles 62 and 66 increases. Thus, the differential pressure (Pb'-Ps) between the intermediate pressure Pb' and the suction pressure Ps increases. The pressure loss and therefore the differential pressure can be adjusted by changing the diameters of the throttles 62 and 66. When the diameters of the throttles are set to increase the pressure loss, the influence of the intermediate pressure Pb' on the back pressure Pb increases. When the diameters of the throttles are set to decrease the pressure loss, the influence of the intermediate pressure Pb' on the back pressure Pb decreases. Note that the flow rate through the throttles 62 and 66 is dependent on the flow rate through the valve section. According to the present embodiment, the valve opening characteristics of the control valve 1 therefore change depending on the flow rate of refrigerant flowing through the valve section.

[0051] In other words, according to the present embodiment, because the intermediate pressure Pb', which is a parameter dependent on the flow rate, is added as a parameter affecting the back pressure Pb, fluctuation of the load in the opening/closing direction of the valve section can be additionally caused to change the valve opening characteristics. This facilitates desirable adjustment of the discharge-pressure dependence and the suction-pressure dependence. As illustrated in FIG. 5, the range of adjustment of the suction-pressure dependence can also be made larger.

[0052] As described above, in the present embodiment, the valve drive member 34 operates in response to reception of the intermediate pressure Pb', which is different from all of the suction pressure Ps, the discharge pressure Pd, and the back pressure Pb. Thus, a design value that affects the intermediate pressure Pb' in the control valve 1 is adjusted, so that the valve section of the control valve 1 autonomously adjusts its opening degree depending on the design value in the back pressure control of the compressor 100. This enables the suction-pressure dependence to increase while the discharge-pressure dependence is maintained.

[0053] The description of the present invention given above is based upon a certain embodiment. The embodiment is intended to be illustrative only and it will be obvious to those skilled in the art that various modifications could be further developed within the technical idea underlying the present invention.

[Modifications]

[0054] FIG. 6 is a cross-sectional view illustrating a structure of a control valve according to a first modification.

[0055] The control valve 201 of the present modification is different from the embodiment in that the first pressure chamber 22 functions as an "intermediate pressure chamber" and that a throttle 23 (orifice) is provided at an outlet of the first pressure chamber 22. The throttle 23 communicates with the port 12. The control valve 201 does not have an intermediate pressure chamber on a lower side of the valve drive member 235. The second pressure chamber 230 is formed on a lower side of the valve drive member 235 in the body 205, and the back pressure Pb is introduced through the slits 31.

[0056] Note that the lower end (the enlarged-diameter part 38) of the valve drive member 235 is located near the open end (lower end) of the body 5. Thus, as illustrated in FIG. 1, the open end of the body 5 can be pressed against a wall face of the fixed scroll 124 of the compressor 100, so that the wall face functions as a stopper that defines the maximum opening degree of the valve section. A shock absorbing member may be provided between the valve drive member 235 and the stopper (wall face). This prevents or reduces breakage and damage of the valve drive member 235.

[0057] The refrigerant introduced in the discharge pressure chamber 20 is reduced in pressure to the intermediate pressure Pb' as a result of passing through the valve section, and then introduced into the first pressure chamber 22. The refrigerant in the first pressure chamber 22 is reduced in pressure to the back pressure Pb as a result of passing through the throttle 23, and then delivered through the port 12 toward the back pressure chamber 156. The first pressure chamber 22 is filled with the intermediate pressure Pb', which is higher than the back pressure Pb and lower than the discharge pressure Pd (Pb<Pb'<Pd).

[0058] The intermediate pressure Pb' is a pressure higher than the suction pressure Ps, lower than the discharge pressure Pd and different from the back pressure Pb. Thus, in a manner similar to the embodiment, the addition of the intermediate pressure Pb', which is a parameter dependent on the flow rate, as a parameter affecting the back pressure Pb facilitates desirable adjustment of the discharge-pressure dependence and the suction-pressure dependence.

[0059] In the embodiment described above, an example of the structure in which the throttles 62 and 66 are provided in the control valve 1 has been presented. In a modification, at least one of the throttles 62 and 66 may be provided in an internal passage (a passage formed in the housing) of the compressor 100. For example, the throttle 62 may be provided in the housing of the compressor, so that the intermediate pressure Pb' resulting from pressure reduction through the throttle 62 is introduced into the second pressure chamber 29 (intermediate pressure chamber). A port through which the throttle and the intermediate pressure chamber communicate with each other may be formed on the body of the control valve.

[0060] FIG. 7 is a partially-enlarged cross-sectional view illustrating structures of a compressor and a control valve according to a second modification.

[0061] The present modification is different from the first modification in that the throttle 23 is provided in an internal passage (a passage formed in the housing) of the compressor 100. The control valve 202 has a structure similar to that of the control valve 201 of the first modification, but does not have the throttle 23 between the first pressure chamber 22 and the port 12. The throttle 23 is provided on the communication passage 193 in the rear housing 122, that is, outside the control valve 202. Refrigerant at the intermediate pressure Pb' is delivered through the port 12. This refrigerant is reduced in pressure to the back pressure Pb as a result of passing through the throttle 23, and is supplied into the back pressure chamber 156.

[0062] A communication passage 250 through which the second pressure chamber 230 of the control valve 202 and the communication passage 197 communicate with each other is formed in the fixed scroll 124 and the center housing 118. Refrigerant that is reduced in pressure to the back pressure Pb as a result of passing through the throttle 23 is introduced into the second pressure chamber 230 through the communication passage 250. Provision of a throttle in the internal passage of the compressor 100 in this manner also enables addition of the intermediate pressure Pb', which is a parameter dependent on the flow rate, which achieves the effects similar to those of the first modification.

[0063] FIG. 8 is a cross-sectional view illustrating a structure of a control valve according to a third modification.

[0064] The control valve 301 of the present modification is different from the embodiment in the locations of the throttles 62 and 66. Seal rings (O rings 340 and 342) are fitted to an upper part and a lower part of the valve drive member 334. The O ring 340 slides along the guiding hole 32 and the O ring 342 slides along the guiding hole 33, which achieves sealing between the inner circumferential face of the body 305 and the outer circumferential face of the valve drive member 334. The O ring 342 is fitted to the outer circumferential face of the diameter-enlarged part 338.

[0065] A lower part of the valve drive member 334 has a stepped circular hole shape that forms an internal passage 336 having a T shape. The suction pressure chamber 28 and the second pressure chamber 29 communicate with each other through the internal passage 336. A passage forming member 350 having a bottomed cylindrical shape is press-fitted in a stepped portion of the internal passage 336. A throttle 66 is provided at the bottom of the passage forming member 350. In the present modification, a lower face of the valve drive member 334 functions as a "pressure-receiving part".

[0066] An annular stopping member 319 is press-fitted into a lower end part of the body 305, and a spring support 320 is coaxially press-fitted inside the stopping member 319. The communication hole 60 axially extends through the center of spring support 320, and the lower end of the communication hole 60 is reduced in diameter to form the throttle 62. The throttles 62 and 66 are located on the axis of the valve drive member 334.

[0067] The spring 40 is provided between the body 305 and the diameter-enlarged part 338, and a spring 352 is provided between the valve drive member 334 and the stopping member 319. The springs 40 and 352 are coaxially arranged around the axis of the valve drive member 334. The spring load applied to the valve drive member 334 can be set by adjusting the amount by which the spring support 320 is press-fitted into the stopping member 319.

[0068] In the present modification as well, the intermediate pressure Pb' changes depending on the flow rate of refrigerant flowing through the throttles 62 and 66. As the flow rate of the refrigerant increases, the load acting on the valve drive member 334 in the valve opening direction increases. When the flow rate is high, the differential pressure (Pb-Pb') between the back pressure Pb and the intermediate pressure Pb' becomes large. As a result, the influence of the intermediate pressure Pb' acting in the valve closing direction becomes smaller, and the valve drive member 334 moves in the valve opening direction. The level of the influence of the intermediate pressure Pb' can be changed by the diameters of the throttles 62 and 66. The flow rate through the throttles 62 and 66 depends on the flow rate through the valve section. Thus, according to the present modification as well, the valve opening characteristics of the control valve 301 change depending on the flow rate of refrigerant through the valve section, which achieves the effects similar to those of the embodiment.

[0069] FIG. 9 is a cross-sectional view illustrating a structure of a control valve according to a fourth modification. FIG. 10 is a cross-sectional view illustrating a structure of a compressor according to the fourth modification.
As illustrated in FIG. 9, the control valve 401 of the present modification is different from the third modification in the structures of pressure chambers in the body 405. The first pressure chamber 22 and the second pressure chamber 29 communicate with each other through an internal passage 436 through the valve drive member 434. Thus, the refrigerant at the back pressure Pb as a result of passing through the valve section is delivered through the internal passage 436, is reduced in pressure to the intermediate pressure Pb' as a result of passing through the throttle 66, and is further reduced in pressure to the suction pressure Ps as a result of passing through the throttle 62. The refrigerant at the suction pressure Ps delivered to the third pressure chamber 30 is delivered to the suction chamber 166 through the slits 31 (see FIG. 10).

[0070] In the present modification, the throttle 66 functions as a "first throttle" that is an inlet of the refrigerant from the first pressure chamber 22 into second pressure chamber 29. The throttle 62 functions as a "second throttle" that is an outlet of the refrigerant from the second pressure chamber 29 to the third pressure chamber 30.

[0071] As illustrated in FIG. 10, in the present modification, a mounting hole 410 is formed in the center housing 118, and the control valve 401 is mounted therein. The discharge chamber 132 and the mounting hole 410 communicate with each other through a communication passage 412 formed in the rear housing 122 and a communication passage 414 formed in the center housing 118. A communication passage 416 through which the back pressure chamber 156 and the mounting hole 410 communicate with each other is also formed in the center housing 118.

[0072] The stopping member 319 is stopped by the open end face of the front housing 120, which prevents the control valve 401 from falling off the mounting hole 410. In the control valve 401, the port 10 communicates with the communication passage 414, and the port 12 communicates with the communication passage 416. In addition, the port 14 and the third pressure chamber 30 communicate with the suction chamber 166 through the open end of the mounting hole 410.

[0073] In the present modification as well, in a manner similar to the embodiment, the addition of the intermediate pressure Pb', which is a parameter dependent on the flow rate, facilitates desirable adjustment of the discharge-pressure dependence and the suction-pressure dependence. Furthermore, because the throttle 66 is on the upstream side of the throttle 62, the third pressure chamber 30 functions as an outlet port of the refrigerant. Specifically, because refrigerant is not introduced through the lower end opening of the body 405, a filter member for preventing entry of foreign materials need not be provide at the lower end opening. Furthermore, because both of the port 14 and the third pressure chamber 30 are filled with the suction pressure Ps, a seal ring (such as an O ring) need not be provided therebetween. The number of components of the control valve 401 can therefore be reduced, and the outer diameter of the control valve 401 can also be minimized.

[0074] FIG. 11 is a cross-sectional view illustrating a structure of a compressor according to a fifth modification. FIG. 12 is a cross-sectional view illustrating a structure of a control valve according to the fifth modification.

[0075] The control valve 501 of the present modification is different from the embodiment in functioning as a control valve for so-called "outflow control" for controlling the flow rate of refrigerant delivered from the back pressure chamber 156 to the suction pressure space 184 (a space filled with the suction pressure Ps).

[0076] As illustrated in FIG. 11, a mounting hole 510 is formed in the rear housing 122, and the control valve 501 is mounted therein. A communication passage 512 through which the discharge chamber 132 and the mounting hole 510 communicate with each other and a communication passage 514 through which the mounting hole 510 and the suction pressure space 184 communicate with each other are formed in the rear housing 122. A communication passage 516 through which the back pressure chamber 156 and the mounting hole 510 communicate with each other is formed in the center housing 118. The control valve 501 controls the flow rate of refrigerant delivered from the back pressure chamber 156 to the suction pressure space 184.

[0077] A communication passage 518 through which the discharge chamber 132 and the communication passage 197 communicate with each other is also formed in the rear housing 122, and a throttle 523 (orifice) is provided on the communication passage 518. Thus, refrigerant at the discharge pressure Pd delivered from the discharge chamber 132 is reduced in pressure as a result of passing through the throttle 523, and supplied as refrigerant at the back pressure Pb into the back pressure chamber 156.

[0078] As illustrated in FIG. 12, the control valve 501 has a body 505 having a stepped cylindrical shape. A valve drive member 534 having a stepped columnar shape is coaxially provided inside the body 505. A guiding hole 532 is formed along the axis through an upper part of the body 505, and an upper part of the valve drive member 534 is slidably supported in the guiding hole 532. A seal ring (O ring 540) is fitted to the outer circumferential face of the valve drive member 534 to prevent leakage of refrigerant through a gap between the valve drive member 534 and the guiding hole 532. A lower end part of the valve drive member 534 has an enlarged diameter to form a valve element 536. In the present modification, the valve element 536 functions as a "pressure-receiving part".

[0079] The port 14 is formed on a lateral side of the body 505, and communicates with the suction pressure chamber 28. A valve seat forming member 519 is provided to axially divide a lower area of the body 505. A valve hole 524 is formed in an upper part of the valve seat forming member 519, and a valve seat 526 having a tapered shape is formed at an open end part of the valve hole 524. A spring 542 that biases the valve element 536 in the valve closing direction is provided between the body 505 and the valve element 536. The valve element 536 touches and leaves the valve seat 526 from the side of the suction pressure chamber 28 to close and open the valve section.

[0080] The communication hole 60 is formed at the center in the lower part of the valve seat forming member 519, and the throttle 62 is formed at the lower end of the communication hole 60. The second pressure chamber 29 is formed on the upper side of the valve seat forming member 519, and the third pressure chamber 30 is formed on the lower side of the valve seat forming member 519. A effective pressure-receiving area A5 of the valve element 536 is sufficiently larger than the cross-sectional area B5 of the guiding hole 532 (A5>B5). Seal rings (O rings 550 and 552) are fitted to the outer circumferential face of the body 505 on the upper side and on the lower side of the port 14. The third pressure chamber 30 communicates with the communication passage 516, and the port 14 communicates with the communication passage 514 (see FIG. 11). The control valve 501 controls the back pressure Pb while changing the opening degree of the valve section depending on the suction pressure Ps, the discharge pressure Pd, and the intermediate pressure Pb'.

[0081] In the present modification, the intermediate pressure Pb' changes depending on the flow rate of refrigerant flowing through the throttle 62. As the flow rate of the refrigerant increases, the load acting on the valve drive member 534 in the valve closing direction increases. As the discharge pressure Pd becomes higher, the back pressure Pb introduced into the suction pressure space 184 through the throttle 523 also becomes higher and, as a result, a pressure loss at the throttle 62 increases. Thus, the differential pressure (Pb'-Ps) between the intermediate pressure Pb' and the suction pressure Ps increases. The pressure loss and therefore the differential pressure can be adjusted by changing the diameter of the throttle 62. The flow rate through the throttle 62 is dependent on the flow rate through the valve section. Thus, according to the present modification as well, the valve opening characteristics of the control valve 501 changes depending on the flow rate of refrigerant flowing through the valve section. The addition of the intermediate pressure Pb' as a parameter affecting the back pressure Pb facilitates desirable adjustment of the discharge-pressure dependence and the suction-pressure dependence.

[0082] FIG. 13 is a cross-sectional view illustrating a structure of a control valve according to a sixth modification.

[0083] The control valve 601 of the present modification is different from the fifth modification in that the suction pressure chamber 28 functions as an "intermediate pressure chamber" and that a throttle 623 (orifice) is provided at an outlet of the suction pressure chamber 28. The throttle 623 communicates with the port 14. The control valve 601 does not have a throttle at the valve seat forming member 619. Refrigerant at the back pressure Pb introduced into the second pressure chamber 29 is reduced in pressure to an intermediate pressure Ps' as a result of passing through the valve section, further reduced in pressure to the suction pressure Ps as a result of passing through the throttle 623, and then delivered through the port 14.

[0084] The intermediate pressure Ps' is a pressure higher than the suction pressure Ps, lower than the discharge pressure Pd, and different from the back pressure Pb. Thus, in the present modification as well, the addition of the intermediate pressure Ps', which is a parameter dependent on the flow rate, as a parameter affecting the back pressure Pb facilitates desirable adjustment of the discharge-pressure dependence and the suction-pressure dependence.

[Other modifications]

[0085] In the embodiment described above, an example of the control valve 1 in which the valve element is formed integrally with the valve drive member has been presented. In a modification, a valve element and a rod-like transmitting member may be connected to form a valve drive member. In other words, a valve drive member may include a plurality of members.

[0086] In the embodiment described above, an example in which the cross-sectional area B of the guiding hole 32 is larger than the cross-sectional area A of the valve hole 24 (B>A) as illustrated in FIG. 3 has been presented. In a modification, the cross-sectional area B of the guiding hole 32 may be equal to the cross-sectional area A of the valve hole 24 (B=A) to cancel the influence of the back pressure Pb on the valve drive member 34.

[0087] In the embodiment described above, an example in which the compressor is applied to a supercritical refrigeration cycle in which carbon dioxide is used as refrigerant has been presented. In a modification, the compressor may be applied to a supercritical refrigeration cycle using refrigerant other than carbon dioxide. Alternatively, the compressor may be applied to a refrigeration cycle that does not function in a supercritical range but in which the pressure of refrigerant becomes high. For example, the compressor may be applied to a refrigeration cycle in which HFC-134a or HFO-1234yf, for example, is used as refrigerant. In this case, a condenser is used as an external heat exchanger, instead of the gas cooler 102, in the refrigeration cycle.

[0088] In the embodiment described above, a compressor mounted in an automotive air conditioner has been presented as an example of a scroll compressor to which the control valve 1 is applied. In a modification, the control valve 1 may be applied to a scroll compressor to be mounted on an air conditioner for general use (household use or professional use). In addition, the control valve 1 may be applied to a scroll compressor in which working fluid other than refrigerant is used.

Claims

1. A control valve (1, 201, 202, 301, 401, 501, 601) to be applied to a scroll compressor (100) including and a suction chamber (166), a discharge chamber (132), and a back pressure chamber (156), for controlling a pressure in the back pressure chamber (156), the control valve (1, 201, 202, 301, 401, 501, 601) comprising:
a valve section for adjusting a flow of fluid introduced from the discharge chamber (132) into the back pressure chamber (156) or fluid delivered from the back pressure chamber (156) into the suction chamber (166), wherein a change in valve opening characteristics is dependent on a flow rate of the fluid flowing through the valve section.

2. The control valve (1, 201, 202, 301, 401, 501, 601) according to claim 1, further comprising:

a pressure-receiving part (38, 334, 434, 536) that receives a pressure that fluctuates depending on the flow rate of the fluid flowing through the valve section, wherein

a load received by the pressure-receiving part (38, 334, 434, 536) acts in an opening/closing direction of the valve section.

3. The control valve (1, 201, 202, 301, 401, 501, 601) according to claim 2, wherein
the fluctuating pressure is an intermediate pressure that is higher than a suction pressure in the suction chamber (166), lower than a discharge pressure in the discharge chamber (132), and different from a pressure in the back pressure chamber (156).

4. The control valve (1, 201, 202, 301, 401, 501, 601) according to claim 3, wherein
the intermediate pressure is generated as a result of provision of a throttle (23, 62, 66, 523, 623) on an internal passage of the control valve (1, 201, 301, 401, 501, 601) or an internal passage of the compressor (100).

5. The control valve (1, 201, 202, 301, 401) according to claim 3 or 4, wherein

the valve section controls the flow rate of the fluid introduced from the discharge chamber (132) into the back pressure chamber (156), and

as the flow rate of the fluid increases, a load acting on the pressure-receiving part (38, 334, 434) in a valve opening direction of the valve section increases.

6. The control valve (501, 601) according to claim 3 or 4, wherein

the valve section controls the flow rate of the fluid delivered from the back pressure chamber (156) into the suction chamber (166), and

as the flow rate of the fluid increases, a load acting on the pressure-receiving part (536) in a valve closing direction of the valve section increases.

7. The control valve (1, 201, 202, 301, 401) according to claim 3, further comprising:

a body (5, 205, 305, 405) having a discharge chamber communication port (10) that communicates with the discharge chamber (132), a back pressure chamber communication port (12) that communicates with the back pressure chamber (156), a suction chamber communication port (14) that communicates with the suction chamber (166), a valve hole (24) through which the discharge chamber communication port (10) and the back pressure chamber communication port (12) communicate with each other, and an intermediate pressure chamber (22, 29) filled with the intermediate pressure as the fluid is introduced into and delivered from the intermediate pressure chamber (22, 29);

a valve element (36) that moves toward and away from the valve hole (24) to adjust an opening degree of the valve section; and

a valve drive member (34, 235, 334, 434) that includes the valve element (36) and operates inside the body (5, 205, 305, 405), wherein

the valve drive member (34, 235, 334, 434) receives the discharge pressure, the suction pressure, a pressure in the back pressure chamber (156), and the intermediate pressure, and thus operates in an opening/closing direction of the valve section.

8. The control valve (1, 201, 301, 401) according to claim 7, wherein
the intermediate pressure chamber (22, 29) includes a throttle (23, 62, 66) at least one of a fluid inlet and a fluid outlet thereof.

9. The control valve (1, 301, 401) according to claim 7 or 8, wherein

the body (5, 305, 405) includes a discharge pressure chamber (20) that communicates with the discharge chamber communication port (10), a control pressure chamber (22) that communicates with the back pressure chamber communication port (12), and a suction pressure chamber (28) that communicates with the suction chamber communication port (14),

the valve drive member (34, 334, 434) separates the suction pressure chamber (28) from the intermediate pressure chamber (29), has the pressure-receiving part (38, 334, 434) slidably supported in the body (5, 305, 405), and operates depending on a differential pressure between the intermediate pressure and the suction pressure received by the pressure-receiving part (38, 334, 434).

10. The control valve (1, 301) according to claim 9, further comprising:

a stopping member (19, 319) that is provided in the body (5,305) to form the intermediate pressure chamber (29) between the stopping member (19, 319) and the pressure-receiving part (38, 334), and restricts operation of the valve drive member (34, 334) in a valve opening direction by stopping the pressure-receiving part (38, 334), wherein

the stopping member (19, 319) includes a first throttle (62) that is a fluid inlet of the intermediate pressure chamber (29).

11. The control valve (1, 301) according to claim 10, wherein
the pressure-receiving part (38, 334) includes a second throttle (66) that is a fluid outlet from the intermediate pressure chamber (29) into the suction pressure chamber (28).

12. The control valve (201) according to claim 7 or 8, wherein

the body (205) includes a discharge pressure chamber (20) that communicates with the discharge chamber communication port (10), and a suction pressure chamber (28) that communicates with the suction chamber communication port (14),

the intermediate pressure chamber (22) is located on a side opposite the discharge pressure chamber (20) with respect to the valve hole (24), and

a throttle (23) that communicates with the back pressure chamber communication port (12) is provided on a fluid outlet side of the intermediate pressure chamber (22).

Drawing