Capacity control valve

Abstract

A capacity control valve includes a valve housing provided with a suction fluid supply chamber to which a suction fluid of suction pressure Ps is supplied, and a control fluid supply chamber to which a control fluid of control pressure Pc is supplied, a CS valve formed by a CS valve element driven in the axial direction by a solenoid, and a CS valve seat provided in a communication passage between the control fluid supply chamber and the suction fluid supply chamber, the CS valve being connectable to and separable from the CS valve seat, and a pressure drive portion arranged in the control fluid supply chamber in a sealed manner and biasing the CS valve element in the opposite direction to the driving direction by the solenoid.

Claims

1. A capacity control valve comprising: a valve housing provided with a suction fluid supply chamber to which a suction fluid of suction pressure is supplied, and a control fluid supply chamber to which a control fluid of control pressure is supplied; a CS valve formed by a CS valve element driven in an axial direction by a solenoid, and a CS valve seat provided in a communication passage between the control fluid supply chamber and the suction fluid supply chamber, the CS valve being connectable to and separable from the CS valve seat; and a pressure drive portion arranged in the control fluid supply chamber in a sealed manner and biasing the CS valve element in an opposite direction to a driving direction of the solenoid, wherein the control fluid is introduced on a first side of the pressure drive portion, and the suction fluid is introduced on a second side of the pressure drive portion, the first side and the second side being opposed to each other through the pressure drive portion in the axial direction; the capacity control valve further comprises a retaining member that retains the pressure drive portion, and the retaining member is provided with a supply port communicating with an inside of the pressure drive portion, the supply port being directed in the axial direction.

2. A capacity control valve comprising: a valve housing provided with a suction fluid supply chamber to which a suction fluid of suction pressure is supplied, and a control fluid supply chamber to which a control fluid of control pressure is supplied; a CS valve formed by a CS valve element driven in an axial direction by a solenoid, and a CS valve seat provided in a communication passage between the control fluid supply chamber and the suction fluid supply chamber, the CS valve being connectable to and separable from the CS valve seat; and a pressure drive portion arranged in the control fluid supply chamber in a sealed manner and biasing the CS valve element in an opposite direction to a driving direction of the solenoid, wherein the control fluid is introduced on a first side of the pressure drive portion, and the suction fluid is introduced on a second side of the pressure drive portion, the first side and the second side being opposed to each other through the pressure drive portion in the axial direction, the capacity control valve further comprises a return spring that is provided separately from the pressure drive portion and biases the CS valve element in the opposite direction to the driving direction of the solenoid, and the CS valve element and the pressure drive portion are out of contact upon a non-driving state of the solenoid.

3. The capacity control valve according to claim 2, wherein the pressure drive portion includes a spring that biases the CS valve element in the opposite direction to the driving direction of the solenoid, and the spring has a spring constant higher than a spring constant of the return spring.

4. The capacity control valve according to claim 2, further comprising a retaining member that retains the pressure drive portion, wherein the retaining member is provided with a supply port communicating with an inside of the pressure drive portion, the supply port being directed in the axial direction.

5. The capacity control valve according to claim 1, further comprising a return spring that is provided separately from the pressure drive portion and biases the CS valve element in the opposite direction to the driving direction of the solenoid, wherein the CS valve element and the pressure drive portion are out of contact upon a non-driving state of the solenoid.

6. The capacity control valve according to claim 5, wherein the pressure drive portion includes a spring that biases the CS valve element in the opposite direction to the driving direction of the solenoid, and the spring has a spring constant higher than a spring constant of the return spring.

7. The capacity control valve according to claim 1, wherein an effective pressure receiving area of the pressure drive portion is larger than an area of a valve opening of the CS valve seat.

8. The capacity control valve according to claim 2, wherein an effective pressure receiving area of the pressure drive portion is larger than an area of a valve opening of the CS valve seat.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a sectional view showing a structure of a capacity control valve according to a first embodiment of the present invention.

(2) FIG. 2 is a sectional view showing a state where a CS valve is opened in a non-energized state of the capacity control valve according to the first embodiment of the present invention.

(3) FIG. 3 is a sectional view showing a state where a drive rod is in contact with a pressure sensitive body in an energized state of the capacity control valve according to the first embodiment of the present invention.

(4) FIG. 4 is an illustrative view of bias force applied to the drive rod at the time of opening and closing the CS valve in the first embodiment of the present invention.

(5) FIG. 5 is an illustrative view showing a case where a pressure difference between suction pressure and control pressure is large in the capacity control valve according to the first embodiment of the present invention.

(6) FIG. 6 is an illustrative view showing a case where the pressure difference between the suction pressure and the control pressure is small in the capacity control valve according to the first embodiment of the present invention.

(7) FIG. 7A is an illustrative view showing a case where a pressure difference between suction pressure and control pressure is large in a capacity control valve according to a second embodiment of the present invention; and FIG. 7B is an illustrative view showing a case where the pressure difference between the suction pressure and the control pressure is small in the same capacity control valve.

DESCRIPTION OF EMBODIMENTS

(8) Modes for carrying out a capacity control valve according to the present invention will be described below based on embodiments.

First Embodiment

(9) A capacity control valve according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. Hereinafter, description will be given with the left and right sides seen from the front side of FIG. 1 being the left and right sides of the capacity control valve.

(10) A capacity control valve V of the present invention is assembled into a variable displacement compressor (not shown) used for an air conditioning system of an automobile, etc. By variably controlling pressure of a working fluid (hereinafter, simply referred to as the “fluid”) serving as a coolant, a discharge amount of the variable displacement compressor is controlled and the air conditioning system is adjusted to have a target cooling ability.

(11) First, the variable displacement compressor will be described. The variable displacement compressor has a casing including a discharge chamber, a suction chamber, a control chamber, and plural cylinders. A communication passage providing direct communication between the discharge chamber and the control chamber is provided in the variable displacement compressor. A fixed orifice 9 is provided in this communication passage (see FIG. 1).

(12) The variable displacement compressor also includes a rotating shaft to be driven and rotated by an engine (not shown) installed outside the casing, a swash plate coupled to the rotating shaft in an eccentric state by a hinge mechanism in the control chamber, and plural pistons coupled to the swash plate and fitted reciprocatably in the respective cylinders. With using the capacity control valve V to be driven to open and close by electromagnetic force, a tilt angle of the swash plate is continuously changed by appropriately controlling pressure in the control chamber while utilizing suction pressure Ps of the suction chamber that suctions the fluid, discharge pressure Pd of the discharge chamber that discharges the fluid pressurized by the pistons, and control pressure Pc of the control chamber that houses the swash plate. Thereby, a stroke amount of the pistons is changed to control a discharge amount of the fluid.

(13) As shown in FIG. 1, the capacity control valve V assembled into the variable displacement compressor adjusts an electric current energized in a coil 86 forming a solenoid 80 and performs open/close control of a CS valve 50 in the capacity control valve V, that is, the valve that opens and closes communication between a control port and a suction port, and by operating a pressure sensitive body 61 serving as a pressure drive portion and controlling the fluid flowing out to the suction chamber from the control chamber, the control pressure Pc in the control chamber is variably controlled. A discharge fluid of the discharge pressure Pd of the discharge chamber is always supplied to the control chamber via the fixed orifice 9, and the control pressure Pc in the control chamber can be increased by closing the CS valve 50 in the capacity control valve V.

(14) Next, a structure of the capacity control valve V will be described. As shown in FIG. 1, the capacity control valve V is mainly formed by a valve housing 10 made of a metal material or a resin material, a CS valve element 51 arranged reciprocatably in the axial direction, the pressure sensitive body 61 arranged in a control fluid supply chamber 17 which is provided in the valve housing 10, the pressure sensitive body that applies bias force to the CS valve element 51 in the axial direction, and the solenoid 80 connected to the valve housing 10, the solenoid that applies drive force to the CS valve element 51.

(15) In the valve housing 10, a Ps port 13 serving as a suction port which communicates with the suction chamber of the variable displacement compressor, a suction fluid supply chamber 16 to which a suction fluid is supplied from the Ps port 13, a Pc port 15 serving as a control port which communicates with the control chamber of the variable displacement compressor, the control fluid supply chamber 17 to which a control fluid is supplied from the Pc port 15, and a communication passage 14 providing communication between the suction fluid supply chamber 16 and the control fluid supply chamber 17 are formed.

(16) A hole portion 10c passing through in the axial direction is formed in an axially left end portion of the valve housing 10, and the hole portion 10c is closed by a lid member 11. Between this valve housing 10 and the lid member 11, the pressure sensitive body 61 is nipped and retained. That is, the lid member 11 functions as a retaining member that retains the pressure sensitive body 61. A supply port 11a passing through in the axial direction is formed in the lid member 11, and the supply port 11a communicates with the suction chamber. The pressure sensitive body 61 may be fixed to the lid member 11 or the valve housing 10 by bonding or welding.

(17) A guide hole 10b passing through in the axial direction is formed in an axially right end portion of the valve housing 10. An axially left end portion of a drive rod 83 to be described later is inserted through the guide hole, and the guide hole functions as a guide when the drive rod 83 is driven in the axial direction.

(18) The solenoid 80 is mainly formed by a casing 81 having an opening portion 81a which is open on the axially left side, a substantially cylindrical center post 82 inserted into the opening portion 81a of the casing 81 from the axially left side and fixed on the radially inner side of the casing 81, the drive rod 83 inserted through an insertion hole 82c of the center post 82 reciprocatably in the axial direction, a movable iron core 84 to which an axially right end portion 83c of the drive rod 83 is inserted and fixed, a coil spring 85 provided between the center post 82 and the movable iron core 84, the coil spring serving as a return spring that biases the movable iron core 84 to the axially right side which is the valve opening direction of the CS valve 50, and the excitation coil 86 wound on the outside of the center post 82 via a bobbin.

(19) The drive rod 83 is formed in a stepped columnar shape, and also serves as the CS valve element 51. From the axially left side, an axially left end portion 83a serving as an axial portion having a small diameter, a large diameter portion 83b having a larger diameter than the axially left end portion 83a, and the axially right end portion 83c having a smaller diameter than the large diameter portion 83b are formed. An axially left end outer diameter portion 53 of the large diameter portion 83b is connectable to and separable from a CS valve seat 10a. That is, the CS valve 50 is formed by the axially left end outer diameter portion 53 of the CS valve element 51 and the CS valve seat 10a, and by connecting and separating the CS valve element 51 to and from the CS valve seat 10a, the CS valve 50 is opened and closed. In a state where the solenoid 80 is turned off, the CS valve element 51 is biased in the valve opening direction of the CS valve 50 by the coil spring 85.

(20) The pressure sensitive body 61 is mainly formed by a film body 62 made of a flexible metal material or a flexible resin material, the film body being extendable and contractible in the axial direction, and a spring 63 arranged inside the film body 62. The film body 62 includes a pressure receiving portion 62a which is orthogonal in the axial direction, a side wall portion 62b extending on the axially left side from a peripheral edge of the pressure receiving portion 62a, and a flange portion 62c extending in the radially outward direction from an axially left end of the side wall portion 62b, and has a hat-shaped section. An O ring is arranged between the flange portion 62c and the lid member 11 and attached to the valve housing 10 in a substantially sealed manner. The supply port 11a of the lid member 11 communicates with the inside 61s serving as a space on the other side of this film body 62, and the suction fluid can flow into the inside from the supply port 11a. That is, the suction fluid exists on the inside of the film body 62, i.e., the inside 61s of the pressure sensitive body 61 and the control fluid in the control fluid supply chamber 17 exists on the outside serving as a space on one side of the film body 62. The spring 63 is a spring having a higher spring constant K63 than a spring constant K85 of the coil spring 85 (K63>K85), and biases to press the pressure receiving portion 62a of the film body 62 to the axially right side.

(21) As shown in FIG. 2, an effective pressure receiving area A of the pressure sensitive body 61 is formed to be larger than a sectional area B of the communication passage 14 serving as a valve opening of the CS valve seat 10a (A>B).

(22) Next, actions of the capacity control valve V, mainly actions of opening and closing the CS valve 50 will be described.

(23) First, a non-energized state of the capacity control valve V will be described. As shown in FIGS. 1 and 2, in the capacity control valve V, in a non-energized state, by pressing the movable iron core 84 to the axially right side by bias force of the coil spring 85, the CS valve element 51 is separated from the CS valve seat 10a, and the CS valve 50 is opened.

(24) At this time, to the CS valve element 51, the bias force F.sub.sp1 of the coil spring 85 and force F.sub.P1 by pressure of the fluid to an axially left end surface of the CS valve element 51 are applied to the axially right side, and force F.sub.P2 by pressure of the fluid to an axially right end surface of the CS valve element 51 is applied to the axially left side. That is, given that the right side is the positive side, force F.sub.rod=F.sub.sp1+F.sub.P1−F.sub.P2 is applied to the CS valve element 51. At the time of opening the CS valve 50, the force F.sub.P1 by the pressure of the fluid to the axially left end surface of the CS valve element 51 is force by pressure of the fluid in the suction fluid supply chamber 16, and the force F.sub.P2 by the pressure of the fluid to the axially right end surface of the CS valve element 51 is force by pressure of the fluid running round from the suction fluid supply chamber 16 to the back surface side of the drive rod 83 via a gap between an inner peripheral surface of the guide hole 10b of the valve housing 10 and an outer peripheral surface of the CS valve element 51. The pressure in the suction fluid supply chamber 16 is based on the control pressure Pc and the suction pressure Ps which are lower than the discharge pressure Pd. Thus, an influence of the forces F.sub.P1, F.sub.P2 by the pressure to the CS valve element 51 is small.

(25) Next, an energized state of the capacity control valve V will be described. As shown in FIGS. 1 and 3, in the capacity control valve V, in an energized state, that is, at the time of normal control, at the time of so-called duty control, when electromagnetic force F.sub.sol generated by applying an electric current to the solenoid 80 exceeds the force F.sub.rod (i.e., F.sub.sol>F.sub.rod), by pulling the movable iron core 84 to the center post 82 side, that is, to the axially left side, and moving the CS valve element 51 fixed to the movable iron core 84 to the axially left side together, the axially left end portion 83a is brought into contact with the pressure sensitive body 61.

(26) Before the axially left end portion 83a is brought into contact with the pressure sensitive body 61, to the CS valve element 51, the electromagnetic force F.sub.sol is applied on the axially left side, and the force F.sub.rod is applied on the axially right side. That is, given that the right side is the positive side, force F.sub.rod−F.sub.sol is applied to the CS valve element 51. After the axially left end portion 83a is brought into contact with the pressure sensitive body 61, force F.sub.bel is further added to the axially right side from the pressure sensitive body 61. The force F.sub.bel applied from the pressure sensitive body 61 is force obtained by subtracting the force F.sub.Pc-Ps based on a pressure difference between the control pressure Pc and the suction pressure Ps from bias force F.sub.sp2 of the spring 63, and given that the right side is the positive side, F.sub.bel=F.sub.sp2−F.sub.Pc-Ps is applied. At the time of considering bias force of the film body 62 itself, the bias force of the film body 62 itself may be added to the bias force of the spring 63 itself.

(27) With reference to FIG. 4, to the CS valve element 51, in a non-energized state of the capacity control valve V, the bias force F.sub.sp1 of the coil spring 85 is applied to the axially right side, and the drive rod 83 is pressed to the right side. Thus, a vibration suspending property of the drive rod 83 is ensured. In an energized state of the capacity control valve V, before the axially left end portion 83a of the drive rod 83 is brought into contact with the pressure sensitive body 61, it is possible to smoothly operate the drive rod 83. After the axially left end portion 83a of the drive rod 83 is brought into contact with the pressure sensitive body 61, the bias force F.sub.sp2 of the spring 63 of the pressure sensitive body 61 having a higher spring constant than the coil spring 85 is dominantly applied to the drive rod 83. Thus, control width of an electric current applied to the solenoid 80 is increased and it is possible to finely make adjustment of an opening degree of the CS valve 50.

(28) Specifically, in a state where the axially left end portion 83a of the drive rod 83 and the pressure sensitive body 61 are in contact with each other, a high spring load is applied. Thus, a stroke of the drive rod 83 per unit applied electric current is shortened, and the opening degree of the CS valve 50 is more easily finely adjusted.

(29) Next, a change in the control pressure and the suction pressure in a state where a predetermined electric current is applied to the solenoid 80, that is, in a state where predetermined electromagnetic force F.sub.sol1 is generated in the solenoid 80 will be described. Hereinafter, a mode when an operation of increasing an output of the air conditioning system is performed, an output of an expansion valve of the air conditioning system is increased, and a flow rate of the suction fluid supplied to the suction chamber of the variable displacement compressor and the suction pressure Ps are increased will be illustrated.

(30) As shown in FIG. 5, in a state where the predetermined electromagnetic force F.sub.sol1 is generated in the solenoid 80 and the CS valve 50 is closed, and in a case where an increase in the suction pressure Ps is small, the pressure difference between the suction pressure Ps in the pressure sensitive body 61 and the control pressure Pc in the control fluid supply chamber 17 is large. Therefore, the pressure sensitive body 61 is more easily contracted by the control pressure Pc in the control fluid supply chamber 17, the CS valve element 51 is seated on the CS valve seat 10a of the valve housing 10, and a closed state of the CS valve 50 is maintained. At the time of closing the CS valve 50, the force F.sub.P1 by the pressure of the fluid to the axially left end surface of the CS valve element 51 is force by the control pressure Pc of the control fluid of the Pc port 15.

(31) Meanwhile, as shown in FIG. 6, in a state where the predetermined electromagnetic force F.sub.sol1 is generated in the solenoid 80 and the CS valve 50 is closed, and in a case where the increase in the suction pressure Ps is large, the pressure difference between the suction pressure Ps in the pressure sensitive body 61 and the control pressure Pc in the control fluid supply chamber 17 is small. Therefore, the pressure sensitive body 61 is less easily contracted by the control pressure Pc in the control fluid supply chamber 17 than the state of FIG. 5, the CS valve element 51 is separated from the CS valve seat 10a of the valve housing 10, and the CS valve 50 is slightly opened.

(32) In such a way, the suction pressure Ps is applied on the inside of the pressure sensitive body 61, and the control pressure Pc is applied on the outside of the pressure sensitive body 61. Thus, even when the output of the expansion valve of the air conditioning system is increased and the suction pressure Ps of the suction fluid supplied to the suction chamber of the variable displacement compressor is radically increased, the pressure sensitive body 61 can utilize the pressure difference between the control pressure Pc of the control fluid and the suction pressure Ps of the suction fluid, and adjust the opening degree of the CS valve 50. Therefore, responsiveness is high even to a radical output change, and it is possible to promptly control the variable displacement compressor to target control pressure Pc.

(33) The effective pressure receiving area A of the pressure sensitive body 61 is formed to be larger than the sectional area B of the communication passage 14. Thus, at the time of driving the solenoid 80, the control pressure Pc is applied in the direction in which the pressure sensitive body 61 is contracted, and it is possible to reliably ease the suction pressure Ps by the control pressure Pc.

(34) The supply port 11a passing through in the axial direction is formed in the lid member 11, and the suction fluid is directed in the axial direction and supplied from the supply port 11a into the pressure sensitive body 61. Thus, it is possible to immediately transmit the suction pressure Ps of the suction fluid to the pressure receiving portion 62a of the pressure sensitive body 61.

(35) The CS valve seat 10a and the guide hole 10b are integrally formed in the valve housing 10. Thus, it is possible to enhance precision of an action of the CS valve element 51.

Second Embodiment

(36) A capacity control valve according to a second embodiment of the present invention will be described with reference to FIG. 7. Duplicated description for the same configurations as the first embodiment is omitted.

(37) As shown in FIG. 7, in the present embodiment, a CS valve 150 is formed by a projecting portion 153 projecting in the radially outward direction from the vicinity of an axially left end portion 831a of a drive rod 831, and a CS valve seat 110a formed in an inner diameter portion in an opening portion on the axially left side of a communication passage 14 of a valve housing 10. That is, the drive rod 831 also serves as a CS valve element 151, and the CS valve 150 is formed by the projecting portion 153 of the CS valve element 151 and the CS valve seat 110a. The projecting portion 153 of the CS valve element 151 is arranged in a control fluid supply chamber 17. By connecting and separating an axially right side surface of the projecting portion 153 to and from the CS valve seat 110a, the CS valve 150 is opened and closed. The drive rod 831 is moved to the axially right side by driving a solenoid. The axially left end portion 831a of the drive rod 831 is connected to a pressure sensitive body 611.

(38) Although not shown, a coil spring serving as a return spring of the present embodiment is arranged to bias the drive rod 831 to the axially left side which is the valve opening direction of the CS valve 150. That is, although the structures are different, both the capacity control valves V of the first and second embodiments are normally-opened valves. Therefore, in a non-energized state of the capacity control valve V, by pressing a movable iron core 84 to the axially left side by bias force of the coil spring, the projecting portion 153 of the CS valve element 151 is separated from the CS valve seat 110a, and the CS valve 150 is opened. At this time, regarding the drive rod 831, in a case where a pressure difference between suction pressure Ps of the pressure sensitive body 611 and control pressure Pc in the control fluid supply chamber 17 is large, bias force of the pressure sensitive body 611 is hardly applied to the drive rod 831.

(39) As shown in FIG. 7A, in an energized state of the capacity control valve V, in a case where the pressure difference between the suction pressure Ps of the pressure sensitive body 611 and the control pressure Pc in the control fluid supply chamber 17 is large, the pressure sensitive body 611 is contracted. Thus, the bias force of the pressure sensitive body 611 is applied in the direction in which the drive rod 831 is pulled to the axially left side, the projecting portion 153 of the CS valve element 151 is separated from the CS valve seat 110a, and the CS valve 150 is slightly opened.

(40) Meanwhile, as shown in FIG. 7B, in an energized state of the capacity control valve V, in a case where the pressure difference between the suction pressure Ps of the pressure sensitive body 611 and the control pressure Pc in the control fluid supply chamber 17 is small, the pressure sensitive body 611 is extended. Thus, the bias force of the pressure sensitive body 611 is applied in the direction in which the drive rod 831 is pushed out to the axially right side, the projecting portion 153 of the CS valve element 151 is seated on the CS valve seat 110a, and the CS valve 150 is closed.

(41) By forming in such a manner, the capacity control valve can be effective for a variable displacement compressor in which the higher the control pressure Pc in a control chamber is, the more a stroke amount of pistons is increased, and the lower the control pressure Pc in the control chamber is, the more the stroke amount of the pistons is decreased.

(42) The embodiments of the present invention are described above with the drawings. However, specific configurations are not limited to these embodiments but the present invention includes changes and additions within the range not departing from the scope of the present invention.

(43) For example, the above embodiments describe the mode that the CS valve element also serves as the drive rod arranged to pass through the coil 86 of the solenoid 80. However, the present invention is not limited to this but the CS valve element may be formed separately from the drive rod and formed reciprocatably in the axial direction together with the drive rod.

(44) The above embodiments describe that the CS valve seat and the guide hole are integrally formed on the inner peripheral surface of the valve housing. However, the present invention is not limited to this but a valve housing having a CS valve seat and a valve housing having a guide hole may be separately provided.

(45) A guide portion is not limited to be formed in the valve housing but may be formed in part of the insertion hole 82c of the center post 82, for example.

REFERENCE SIGNS LIST

(46) 10 Valve housing 10a CS valve seat 11 Lid member 11a Supply port 13 Ps port 14 Communication passage (valve opening) 15 Pc port 16 Suction fluid supply chamber 17 Control fluid supply chamber 50 CS valve 51 CS valve element 61 Pressure sensitive body (pressure drive portion) 61s Inside of pressure drive portion 63 Spring 80 Solenoid 83 Drive rod 85 Coil spring (return spring) 110a CS valve seat 150 CS valve 151 CS valve element 611 Pressure sensitive body 831 Drive rod Pc Control pressure Pd Discharge pressure Ps Suction pressure V Capacity control valve