Control valve

Abstract

To provide a structure capable of reducing slide resistance by a seal ring, in a control valve in which the seal ring is disposed on a slide portion of a valve element.SOLUTION: A control valve includes: a body 10 coaxially having a valve hole 30 and a guide hole 38; a valve element 40 slidably supported by the guide hole 38, and opening and closing a valve portion 2 by being kept into contact with and separated from the valve hole 30; and a seal ring 124 fitted to an annular recessed portion 122 formed on one of an outer peripheral surface of the valve element 40 and an inner peripheral surface of the guide hole 38 for restricting leakage of a refrigerant from a high pressure side to a low pressure side through a gap between the valve element 40 and the guide hole 38. A contact area of the seal ring 124 with the other of the outer peripheral surface of the valve element 40 and the inner peripheral surface of the guide hole 38, is smaller than a contact area with a low pressure-side face of the recessed portion 122.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control valve, and more particularly to a seal structure for a sliding portion. [Background technology]

[0002] Automotive air conditioners are generally configured with a compressor, a condenser, an expansion device, an evaporator, and other components arranged in a refrigeration cycle. The refrigeration cycle is provided with various control valves, such as an expansion valve as an expansion device, to control the flow of the refrigerant. With the recent spread of electric vehicles, motor-operated valves equipped with a motor as a drive unit are becoming more widely used.

[0003] The motor-operated valve includes a shaft that is coaxial with the rotor, a valve body that can be displaced integrally with the shaft, and a screw feed mechanism that converts the rotational motion of the rotor into the translational motion of the shaft. The valve body can be operated in the opening and closing directions of the valve section by the rotation of the rotor. One such motor-operated valve has a body that has a valve hole and a guide hole that are coaxial with each other, and supports the valve body so that it can slide along the guide hole. An O-ring is interposed between the valve body and the guide hole, and the flow of refrigerant through the sliding portion between the two is restricted (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-41596 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such motor-operated valves, the O-ring increases the sliding resistance of the valve body, which increases the rotational torque of the motor. For this reason, it is necessary to devise a way to maintain good sliding properties of the valve body while suppressing the rotational load of the motor. In this regard, measures such as applying a lubricating coating to the O-ring can be considered, but there is a concern that the coating will peel off with repeated use. This problem is not limited to motor-operated valves used in refrigeration cycles, but can occur in any control valve that has a seal ring interposed between the valve body and the guide hole.

[0006] An object of the present invention is to provide a structure for reducing the sliding resistance caused by a seal ring in a control valve in which a seal ring is disposed on the sliding portion of a valve body. [Means for solving the problem]

[0007] A control valve according to one embodiment of the present invention comprises a body having a valve hole and a guide hole coaxially arranged therewith, a valve element slidably supported in the guide hole and adapted to open and close a valve portion by approaching and separating from the valve hole, and a seal ring fitted into an annular recess provided in one of an outer circumferential surface of the valve element and an inner circumferential surface of the guide hole for restricting leakage of refrigerant from the high pressure side to the low pressure side through a gap between the valve element and the guide hole. The contact area of ​​the seal ring with the other of the outer circumferential surface of the valve element and the inner circumferential surface of the guide hole is smaller than the contact area with the low pressure side of the recess.

[0008] According to this aspect, when a recess is provided on the outer peripheral surface of the valve body, the contact area between the seal ring and the guide hole can be reduced, and the sliding resistance caused by the seal ring can be reduced. When a recess is provided on the inner peripheral surface of the guide hole, the contact area between the seal ring and the valve body can be reduced, and the sliding resistance caused by the seal ring can be reduced.

[0009] A control valve according to another aspect of the present invention includes a body having a valve hole and a guide hole coaxially arranged therewith, a valve element slidably supported in the guide hole and adapted to open and close a valve portion by approaching and separating from the valve hole, and a seal ring fitted into an annular recess provided on one of an outer circumferential surface of the valve element and an inner circumferential surface of the guide hole for restricting leakage of refrigerant from the high pressure side to the low pressure side through a gap between the valve element and the guide hole. The cross section of the seal ring has a shape that causes a rotational moment or a bending moment to act due to a pressure difference between the high pressure side and the low pressure side. Due to the pressure difference, the contact area of ​​the seal ring with the other of the outer circumferential surface of the valve element and the inner circumferential surface of the guide hole becomes smaller than the contact area with the low pressure side of the recess.

[0010] According to this embodiment, the cross section of the seal ring rotates or bends due to the pressure difference acting on the valve body. As a result, when a recess is provided on the outer peripheral surface of the valve body, the contact area between the seal ring and the guide hole can be reduced, and the sliding resistance caused by the seal ring can be reduced. When a recess is provided on the inner peripheral surface of the guide hole, the contact area between the seal ring and the valve body can be reduced, and the sliding resistance caused by the seal ring can be reduced. Effect of the Invention

[0011] According to the present invention, in a control valve in which a seal ring is disposed on the sliding portion of a valve body, a structure for reducing the sliding resistance caused by the seal ring can be provided. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view illustrating a motor-operated valve according to an embodiment. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Diagram 3] FIG. 4 is a diagram illustrating a configuration of an internal passage of the first valve body. [Figure 4] FIG. 4 is an enlarged view of a main portion around the first valve body. [Diagram 5] 4A to 4C are diagrams illustrating the operation process of the motor-operated valve. [Figure 6] FIG. 4 is a partially enlarged view showing a structure for reducing sliding resistance using a seal ring. [Figure 7]FIG. 4 is a diagram showing the differential pressure reducing effect achieved by the structure of the first valve. [Figure 8] FIG. 4 is a diagram showing the differential pressure reducing effect achieved by the structure of the first valve. [Figure 9] FIG. 4 is a diagram showing a change in a valve closing direction load that the first valve body receives in response to a valve opening operation. [Figure 10] 13 is a partial enlarged view showing the structure of a seal ring according to a modified example. FIG. [Figure 11] 13 is a partial enlarged view showing the structure of a seal ring according to another modified example. FIG. [Figure 12] 13 is a diagram showing the results of an analysis of the deformation of a seal ring due to a pressure difference. FIG. [Figure 13] FIG. 13 is a partial enlarged view showing a seal structure according to another modified example. [Figure 14] 13 is a partial enlarged view showing the configuration of a first valve according to another modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, for convenience, the positional relationship of each structure may be expressed based on the illustrated state. In addition, in the following embodiment and its modified examples, substantially the same components are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0014] FIG. 1 is a cross-sectional view illustrating a motor-operated valve according to an embodiment. The motor-operated valve 1 is applied to a refrigeration cycle of a vehicle air conditioner (not shown). The motor-operated valve 1 is a composite valve that has a large-diameter first valve 2 and a small-diameter second valve 4 arranged coaxially and drives these valves with a shared actuator. The first valve 2 and the second valve 4 are each proportional valves with adjustable valve opening. The first valve 2 can also function as an on-off valve that opens and closes the refrigerant circulation passage. The second valve 4 can also function as an expansion valve that throttles and expands the refrigerant from the upstream side.

[0015] The motor-operated valve 1 is constructed by assembling a valve body 6 and a motor unit 8. The valve body 6 and the motor unit 8 are fixed via a connecting member 9. The valve body 6 has a common body 10 that houses the first valve 2 and the second valve 4. The body 10 is constructed by coaxially assembling a first body 12, a second body 14 and a guide member 16. In this embodiment, all of the bodies are made of stainless steel (hereinafter referred to as "SUS").

[0016] The first body 12 is in the shape of a cylinder (block) with a bottom, with an inlet port 18 opening at the bottom of one side thereof and an outlet port 20 opening at the top of the opposite side thereof. A refrigerant passage 22 is formed in the first body 12, connecting the inlet port 18 and the outlet port 20. The refrigerant from the upstream side is introduced into the refrigerant passage 22 via the inlet port 18, passes through a valve portion, and is then discharged to the downstream side via the outlet port 20. A stepped circular mounting hole 26 is provided in the center of the upper half of the first body 12, and communicates with an intermediate portion of the refrigerant passage 22. The diameter of the mounting hole 26 increases stepwise toward the top, and the guide member 16 and the second body 14 are inserted through the mounting hole 26 in that order for assembly.

[0017] An annular valve seat forming member 28 is press-fitted into a step provided in the middle of the refrigerant passage 22. A first valve hole 30 that is coaxial with the mounting hole 26 is formed inside the valve seat forming member 28. A first valve seat 32 is formed at the downstream opening of the first valve hole 30. Rubber is baked onto the inner circumferential surface of the valve seat forming member 28 along the first valve hole 30 and the first valve seat 32 to improve sealing performance (described in detail later).

[0018] The second body 14 has a stepped cylindrical shape, and its lower half is inserted into the mounting hole 26 and assembled to the first body 12. A female thread 33 is formed on the inner peripheral surface of the mounting hole 26, and a male thread 35 is formed on the outer peripheral surface of the lower part of the second body 14. The second body 14 is fastened to the first body 12 by these threads. A seal receiving portion 34 consisting of an annular groove is formed on the outer peripheral surface of the second body 14 (slightly above the male thread 35), and a seal ring 36 (O-ring) is fitted into it. The seal ring 36 is interposed between the mounting hole 26 and the second body 14, thereby preventing refrigerant from leaking from the inside of the valve main body 6 to the outside.

[0019] The guide member 16 is obtained by applying lubricating plating to a cylindrical member made of SUS. The lower portion of the guide member 16 is slightly enlarged in diameter and press-fitted into the lower portion of the mounting hole 26. This fixes the guide member 16 to the first body 12. A guide hole 38 is formed by the inner peripheral surface of the guide member 16. The lower half of the second body 14 is inserted into the annular space formed between the inner peripheral surface of the mounting hole 26 and the outer peripheral surface of the guide member 16. A predetermined clearance is provided between the second body 14 and the guide member 16, so that the two do not come into contact with each other.

[0020] A first valve body 40 is disposed inside the guide member 16. The first valve body 40 is cylindrical with a bottom, and is slidably supported in the guide hole 38. The first valve body 40 opens and closes the first valve 2 by being attached to and detached from the first valve seat 32 from the downstream side. Meanwhile, an internal passage 42 is formed in the first valve body 40, and a second valve hole 44 is formed in the middle of the internal passage 42. A second valve seat 46 is formed at the upstream opening of the second valve hole 44.

[0021] An actuating rod 48 extending from the rotor 60 of the motor unit 8 is inserted into the inside of the body 10. The lower part of the actuating rod 48 is coaxially inserted into the first valve body 40. The actuating rod 48 is obtained by cutting a bar material made of a non-magnetic metal, and a needle-shaped second valve body 50 is integrally provided at its lower part. The second valve body 50 opens and closes the second valve 4 by being attached to and detached from the second valve seat 46 from the upstream side.

[0022] A guide member 52 is erected at the center of the upper part of the second body 14. The guide member 52 is obtained by cutting a tube made of a non-magnetic metal into a stepped cylindrical shape, and a male thread 54 is formed on the outer circumferential surface of the axial center part. The lower end part of the guide member 52 has a large diameter, and the large diameter part 56 is press-fitted into the upper center of the second body 14 and fixed coaxially. The guide member 52 supports the operating rod 48 axially slidably with its inner circumferential surface, and supports the rotating shaft 62 of the rotor 60 rotatably and slidably with its outer circumferential surface.

[0023] A spring 58 (functioning as a "biasing member") is interposed between the guide member 52 and the first valve body 40 to bias the first valve body 40 in the valve closing direction. A radially protruding locking portion 59 is provided on the operating rod 48 slightly above the second valve body 50. The locking portion 59 is made of, for example, an E-ring. By hooking the locking portion 59 on the first valve body 40, the first valve body 40 can be pulled up in the valve opening direction against the biasing force of the spring 58. A mechanism that operatively connects the first valve body 40 and the second valve body 50 via the operating rod 48 so that they can be displaced together is called an "operational connection mechanism." Details of this mechanism will be described later.

[0024] On the other hand, the motor unit 8 is configured as a stepping motor including a rotor 60 and a stator 64. The motor unit 8 has a cylindrical can 66 with a bottom, with the rotor 60 disposed inside the can 66 and the stator 64 disposed outside the can 66. The can 66 is a cylindrical member with a bottom that covers the space in which the second valve body 50 and its drive mechanism are disposed and contains the rotor 60, and defines an inner pressure space (internal space) where the pressure of the refrigerant acts and an outer non-pressurized space (external space) where the pressure of the refrigerant does not act.

[0025] The can 66 is made of a non-magnetic metal (SUS in this embodiment), and is assembled coaxially with its lower portion being fitted onto the upper end of the second body 14. The body 10 and the can 66 are fixed and sealed by applying a full circumference weld (not shown) along the boundary between the lower end of the can 66 and the second body 14. The space surrounded by the body 10 and the can 66 forms the above-mentioned pressure space.

[0026] By making the guide member 16 a separate member from the second body 14, the welded part (second body 14) and the lubricant-coated part (guide member 16) can be produced separately. This simplifies the manufacturing process because it is sufficient to immerse the entire material of the guide member 16 in a plating solution without the need to take the time to paint or deposit a plating film on the guide hole 38.

[0027] The stator 64 is constructed by assembling a bobbin 70 around which a coil 68 is wound, to a yoke 72 having a plurality of pole teeth. The stator 64 is provided integrally with a case 76 of the motor unit 8. That is, the case 76 is obtained by injection molding (also called "insert molding" or "mold molding") of a corrosion-resistant resin material. The stator 64 is covered with the molded resin obtained by the injection molding. The case 76 is made of the molded resin. Hereinafter, the molded product of the stator 64 and the case 76 will also be referred to as a "stator unit 78."

[0028] The stator unit 78 has a hollow structure, and is assembled to the body 10 while the can 66 is coaxially inserted therethrough. A seal receiving portion 80 consisting of an annular groove is formed on the outer peripheral surface of the upper portion of the second body 14, and a seal ring 82 (O-ring) is fitted into the seal receiving portion 80. The seal ring 82 is interposed between the second body 14 and the case 76, thereby preventing the outside atmosphere (water, etc.) from entering the gap between the can 66 and the stator 64.

[0029] The rotor 60 includes a cylindrical rotor core 84 attached to the rotating shaft 62, and a rotor magnet 86 provided on the outer circumferential surface of the rotor core 84. The rotor core 84 is attached to the rotating shaft 62. The rotor magnet 86 is magnetized (magnetized) into multiple poles in its circumferential direction.

[0030] The rotating shaft 62 is a cylindrical shaft with a bottom, and is fitted onto the guide member 52 with its open end facing downward. A female thread 88 is formed on the inner peripheral surface of the lower part of the rotating shaft 62, and meshes with the male thread 54 of the guide member 52. A screw feed mechanism 90 formed by these threads converts the rotational motion of the rotor 60 into axial motion of the actuation rod 48. This causes the second valve body 50 to move (rise and fall) in the axial direction, that is, in the opening and closing direction of the valve portion.

[0031] The upper part of the actuation rod 48 is reduced in diameter, and the reduced diameter portion 92 penetrates the bottom 94 of the rotary shaft 62. An annular stopper 96 is fixed to the tip of the reduced diameter portion 92. Meanwhile, a spring 98 that urges the actuation rod 48 downward (i.e., in the valve closing direction) is interposed between the base end of the reduced diameter portion 92 and the bottom 94. With this configuration, when the valve is opened, the actuation rod 48 is displaced integrally with the rotor 60 in such a manner that the stopper 96 is engaged with the bottom 94. Meanwhile, when the valve is closed, the spring 98 is compressed by the reaction force that the second valve body 50 receives from the second valve seat 46. The elastic reaction force of the spring 98 at this time can press the second valve body 50 against the second valve seat 46, thereby improving the seating performance (valve closing performance) of the second valve body 50.

[0032] The motor unit 8 has a circuit board 100 on the outside of the can 66. The circuit board 100 is fixed inside the case 76. In this embodiment, various circuits functioning as a control unit and a communication unit are mounted on the lower surface of the circuit board 100. Specifically, a drive circuit for driving the motor, a control circuit (microcomputer) for outputting a control signal to the drive circuit, a communication circuit for the control circuit to communicate with an external device, a power supply circuit for supplying power to each circuit and the motor (coil), etc. are mounted. The upper end of the case 76 is closed by a lid 77. The circuit board 100 is disposed in the space below the lid 77 of the case 76.

[0033] A terminal 102 connected to the coil 68 extends from the bobbin 70 and is connected to a circuit board 100. A power supply terminal, a ground terminal, and a communication terminal (collectively referred to as "connection terminals 104") extend from the circuit board 100 and are each drawn out to the outside through a side wall of the case 76. A connector portion 106 is integrally provided on the side of the case 76, and the connection terminal 104 is disposed inside the connector portion 106.

[0034] Fig. 2 is an enlarged view of part A in Fig. 1. Fig. 3 is a diagram showing the configuration of the internal passage of the first valve body 40. Fig. 3(A) corresponds to a cross section viewed from the arrow BB in Fig. 2, and Fig. 3(B) corresponds to a cross section viewed from the arrow C in Fig. 2. Fig. 4 is an enlarged view of the main parts around the first valve body 40. Fig. 4(A) is an enlarged view of part D in Fig. 2, and Fig. 4(B) is an enlarged view of part E in Fig. 2.

[0035] As shown in Fig. 2, the first valve body 40 is cylindrical with a bottom having a sufficient thickness. A back pressure chamber 108 is formed above the first valve body 40. The back pressure chamber 108 is a space surrounded by the guide member 52, the second body 14, the guide member 16, and the first valve body 40. A valve chamber 110 is formed inside the first valve body 40 (above the bottom). A bottomed, stepped cylindrical operating connection member 112 is coaxially inserted and fixed to the upper part of the first valve body 40. The operating connection member 112 is made of a material, such as brass, which is softer and more easily machinable than the first valve body 40.

[0036] The operating connecting member 112 has an insertion hole 114 in the center of its bottom. The operating rod 48 coaxially passes through the insertion hole 114. A plurality of communication holes 116 that communicate between the inside and the outside are provided in the side of the operating connecting member 112. The communication holes 116 communicate between the valve chamber 110 and the back pressure chamber 108. The operating connecting member 112 is fixed to the first valve body 40 by having its upper portion press-fitted into the upper end opening of the first valve body 40.

[0037] A flange portion 118 extending radially outward is provided at the upper end of the operating connection member 112. Meanwhile, an annular step 120 is provided along the outer periphery of the upper end of the first valve body 40. An annular seal accommodating portion 122 is formed at the upper portion of the first valve body 40 by the flange portion 118 and the step 120. A seal ring 124 is fitted into the seal accommodating portion 122. The seal ring 124 regulates the flow of refrigerant through the gap between the first valve body 40 and the guide member 16. The seal ring 124 and its surroundings will be described in detail later.

[0038] The bottom of the operating connection member 112 also functions as a spring bearing that supports the spring 58. That is, the spring 58 is coaxially inserted around the operating rod 48 and is interposed between the bottom of the guide member 52 and the bottom of the operating connection member 112. The biasing force of the spring 58 is transmitted to the first valve body 40 via the operating connection member 112. In addition, the valve-opening operation of the second valve body 50 causes the locking portion 59 to displace relative to the first valve body 40 and come into contact with the bottom surface of the operating connection member 112 and push it up, thereby operating the first valve body 40 in the valve-opening direction.

[0039] The surface of the guide hole 38 facing the outer circumferential surface of the first valve body 40 is provided with an expanded diameter portion 126 that is partially expanded slightly. The expanded diameter portion 126 is provided from the axial center to the lower portion of the guide hole 38, and forms a clearance between the first valve body 40 and the guide hole 38. However, as shown in the figure, the first valve body 40 abuts against the guide hole 38 at its upper and lower portions, allowing stable sliding. By providing the expanded diameter portion 126 in this manner, the sliding area between the first valve body 40 and the guide hole 38 is limited, thereby reducing the sliding resistance of the first valve body 40.

[0040] As described above, the guide hole 38 is lubricated with a plating. The material of the lubricating plating may be a known lubricating plating material such as nickel-phosphorus (Ni-P) containing polytetrafluoroethylene (hereinafter, sometimes referred to as "PTFE"). This surface treatment of the sliding surface also reduces the sliding resistance.

[0041] A plurality of (five in this embodiment) communication holes 130 (small holes) are provided through the bottom of the first valve body 40 in parallel with the axis (FIGS. 3(A) and (B)). The lower end openings of these communication holes 130 serve as inlet ports 132. The communication holes 130 communicate the upstream side of the first valve seat 32 in the first valve hole 30 with the valve chamber 110. The communication holes 130, the valve chamber 110, and the communication holes 116 constitute a "communication passage" that communicates the upstream side of the first valve seat 32 with the back pressure chamber 108. In addition, a downstream passage 134 extending perpendicular to the axis is provided at the bottom of the first valve body 40. The downstream passage 134 has an outlet port 136 that opens toward the outlet port 20.

[0042] The second valve hole 44 communicates between the valve chamber 110 and the downstream passage 134. The communication hole 130 is disposed so as not to intersect with the downstream passage 134. The flow passage cross section of the downstream passage 134 is sufficiently larger than the flow passage cross section of the communication hole 130. The multiple communication holes 130, the valve chamber 110, the second valve hole 44 and the downstream passage 134 form the internal passage 42 of the first valve body 40. The tip of the second valve body 50 passes through the second valve hole 44 and is attached to and detached from the second valve seat 46 by its tapered surface.

[0043] When the first valve 2 is closed or slightly opened as shown in the figure, the pressure on the upstream side of the first valve seat 32 (upstream pressure P1) is higher than the pressure on the downstream side of the first valve seat 32 (downstream pressure P2). Meanwhile, since the back pressure chamber 108 communicates with the upstream side of the first valve seat 32 via the valve chamber 110 and the communication hole 130, the pressure in the back pressure chamber 108 (also referred to as "back pressure") becomes approximately equal to the upstream pressure P1. As a result, the fluid pressure acting on the first valve body 40 is almost canceled.

[0044] In this embodiment, in order to improve the valve closing performance of the first valve 2, the sliding portion diameter d1 (the inner diameter of the guide hole 38) of the first valve body 40 is made slightly larger than the seal portion diameter d2 (the outer diameter of the valve seat). However, because the difference in diameter is minute, as described above, the fluid pressure acting on the first valve body 40 is almost cancelled out. This makes it possible to reduce the resistance when the first valve body 40 is pulled up in the valve opening direction, and to suppress the rotational torque (rotational driving force) of the motor unit 8 required to open the first valve 2.

[0045] Meanwhile, a pressure difference (P1-P2) between the upstream pressure P1 and the downstream pressure P2 occurs in the gap between the first valve body 40 and the guide hole 38. In this regard, in this embodiment, the seal ring 124 is provided to prevent the refrigerant from leaking from the high pressure side to the low pressure side through the gap.

[0046] 4(A), the seal accommodating portion 122 has a bottom surface 140, a high-pressure side surface 142, and a low-pressure side surface 144, and is an annular recess provided along the upper outer peripheral surface of the first valve body 40. On the other hand, the seal ring 124 is a triangular ring having a triangular cross section, and one vertex of the triangular ring abuts against the inner peripheral surface of the guide hole 38.

[0047] More specifically, the cross-sectional shape of the seal ring 124 is a right-angled triangle with a rounded apex. An inner circumferential surface 146 of the seal ring 124 is flat, and a lower surface 148 that forms a right angle with the inner circumferential surface 146 abuts against the low-pressure side surface 144 of the seal accommodating portion 122. An upper surface 150 of the seal ring 124 is an inclined surface (tapered surface), and an outer circumferential surface 152 of the seal ring 124 is formed by the apex where the upper surface 150 and the lower surface 148 are connected. The outer circumferential surface 152 of the seal ring 124 slides in the guide hole 38.

[0048] Due to this configuration, the contact area of ​​the seal ring 124 with the inner circumferential surface of the guide hole 38 is smaller than the contact area with the low-pressure side surface 144 of the seal accommodating portion 122. In other words, the sliding area between the seal ring 124 and the guide hole 38 can be made smaller than in the case of an O-ring or the like, and the sliding resistance of the first valve body 40 can be reduced.

[0049] The width of the seal accommodating portion 122 (i.e., the distance between the high pressure side surface 142 and the low pressure side surface 144) is larger than the axial width of the seal ring 124 (i.e., the axial width of the first valve body 40). When the first valve 2 is in a closed or slightly open state, a differential pressure (P1-P2) acts on the seal ring 124, so that the seal ring 124 comes into close contact with the low pressure side surface 144 as shown in the figure. A gap S is formed between the bottom surface 140 of the seal accommodating portion 122 and the inner peripheral surface 146 of the seal ring 124 (between the opposing surfaces of the bottom surface 140 and the seal ring 124). Therefore, even if the seal ring 124 is compressed and deformed in the axial direction due to the differential pressure, the inner peripheral surface 146 does not come into contact with the bottom surface 140. Therefore, the seal ring 124 is not pressed against the guide hole 38 by the reaction force from the bottom surface 140, and an increase in sliding resistance can be avoided.

[0050] As shown in FIG. 4B, the valve seat forming member 28 has rubber 162 baked along the inner circumferential surface of the main body 160 made of SUS. The upper end opening of the valve seat forming member 28 has a first tapered surface 164 that functions as the first valve seat 32 (attachment / detachment surface) and a second tapered surface 166 that forms the opening end of the first valve hole 30. The first valve hole 30 has a two-stage tapered structure including a straight portion 168 parallel to the axis of the first valve body 40 between the first tapered surface 164 and the second tapered surface 166. A right-angled step portion 170 is provided in the portion of the main body 160 corresponding to the first valve seat 32, and a thick portion of the rubber 162 is provided between the first tapered surface 164 and the first tapered surface 164. That is, the thickness of the rubber 162 is increased at the position of the first valve seat 32. This increases the durability of the first valve seat 32.

[0051] The first valve body 40 has a small diameter portion 172 that is slightly reduced in diameter at its lower end (tip portion). The outer periphery at the lower end of the small diameter portion 172 is an edge portion 174. The edge portion 174 has a cross section that is almost perpendicular, but is slightly chamfered with a radius so as not to damage the first valve seat 32. The first valve 2 has, as its opening and closing structure, an insertion / removal structure in which the small diameter portion 172 is coaxially inserted and removed from the first valve hole 30, and an attachment / detachment structure in which the edge portion 174 is attached and detached to the first tapered surface 164 with the small diameter portion 172 inserted into the first valve hole 30.

[0052] Next, the operation of the motor-operated valve 1 will be described. Figure 5 is a diagram showing the operation process of the motor-operated valve 1. Figure 5(A) shows the first valve 2 and the second valve 4 in a closed state. Figure 5(B) shows the first valve 2 in a closed state and the second valve 4 in an open state. Figure 5(C) shows the first valve 2 and the second valve 4 in an open state.

[0053] When the motor unit is driven in the valve opening direction to operate the operating rod 48 upward, the second valve body 50 separates from the second valve seat 46 (FIGS. 5(A) and 5(B)). This allows communication between the communication hole 130, the valve chamber 110, the second valve hole 44, and the downstream passage 134. The refrigerant from the upstream side flows through the internal passage 42 of the first valve body 40 and is discharged to the downstream side via the second valve 4. At this time, the second valve 4 can be adjusted to a predetermined opening degree to function as an expansion valve.

[0054] When the actuating rod 48 is further actuated in the valve opening direction, the locking portion 59 engages with the actuating connection member 112, and the actuating rod 48 and the first valve body 40 are operatively connected (FIG. 5(C)). Then, the actuating rod 48 pulls up the first valve body 40 against the biasing force of the spring 58. This causes the first valve body 40 to separate from the first valve seat 32, and the first valve 2 opens. The refrigerant flows downstream via both the first valve 2 and the second valve 4. At this time, a large flow rate of refrigerant can be passed, but the flow rate can be adjusted by the opening degree of the first valve 2.

[0055] When the motor unit is driven in the valve closing direction, the rod 48 moves downward in the opposite direction to the above. At this time, the first valve body 40 moves in the valve closing direction while maintaining the operative connection with the rod 48 due to the biasing force of the spring 58. First, the first valve body 40 is seated on the first valve seat 32, and the first valve 2 is in the closed state. When the rod 48 is further operated in the valve closing direction, the locking portion 59 is released from the operative connection member 112, and the operative connection between the rod 48 and the first valve body 40 is released. After that, the second valve body 50 is seated on the second valve seat 46, and the second valve 4 is in the closed state. Note that the load in the valve closing direction to the first valve body 40 is not applied from the motor unit but is applied by the spring 58 in a specific operating state of the motor-operated valve 1, such as when the second valve 4 is in the open state.

[0056] Next, the effects of this embodiment will be described. Fig. 6 is a partially enlarged view showing a sliding resistance reduction structure using a seal ring 124. Fig. 6(A) shows the structure of this embodiment, and Fig. 6(B) shows the structure of Comparative Example 1. Comparative Example 1 shows the case where an O-ring is used as the seal ring.

[0057] As already explained, the seal ring 124 of this embodiment has a right-angled triangular cross section, and one apex (outer peripheral surface 152) is brought into close contact with the guide hole 38 to ensure sealing (FIG. 6(A)). The seal ring 124 abuts on a flat surface of a complementary shape to the low-pressure side surface 144 of the seal accommodating portion 122, and the contact area is sufficiently large. Therefore, even when subjected to a pressure difference (P1-P2), the seal ring 124 is unlikely to deform, and maintains its shape stably. As a result, the first valve body 40 can slide stably along the guide hole 38 while suppressing sliding resistance to a small value.

[0058] In contrast, the O-ring 224 of Comparative Example 1 is a typical seal ring to be attached to a sliding portion, but its contact area with the inner circumferential surface of the guide hole 38 is larger than its contact area with the low-pressure side surface 144 of the seal accommodating portion 122. When the O-ring 224 receives the differential pressure (P1-P2), it is crushed in the axial direction and expands in the radial direction. Therefore, the sliding resistance of the first valve body 40 is larger than that of this embodiment. In other words, by employing the seal ring 124 of this embodiment, the sliding resistance can be effectively reduced.

[0059] Figures 7 and 8 are diagrams showing the differential pressure reduction effect due to the structure of the first valve 2. Figures 7(A) to (D) show the change in pressure-receiving area when the valve is open when the valve structure of this embodiment is adopted. Figures 8(A) to (D) show the change in pressure-receiving area when the valve is open when the valve structure of Comparative Example 2 is adopted. The valve structure of Comparative Example 2 does not have the insertion / removal structure of this embodiment (see Figure 4(B)).

[0060] Here, φA in the figure is the pressure-receiving diameter of the back pressure that the first valve body 40 receives, and is equal to the sliding portion diameter d1 in FIG. 2. φB in the figure is the pressure-receiving diameter of the seal portion of the first valve body 40, and is equal to the seal portion diameter d2 in FIG. 2 when the valve is closed. As already explained, in this embodiment, d1>d2. Although the pressure-receiving diameter φA is constant depending on the open / closed state of the first valve 2, the pressure-receiving diameter φB changes. In the first valve body 40, a differential pressure (P1-P2) acts in the valve closing direction on a pressure-receiving area corresponding to the pressure-receiving diameter difference (φA-φB).

[0061] In this embodiment, when the first valve 2 is in the closed state, the first valve body 40 is seated on the first valve seat 32, so that the pressure-receiving diameter φB is approximately equal to the outer diameter of the edge portion 174 (FIG. 7(A)). At this time, the differential pressure (P1-P2) is at its maximum, but due to the above-mentioned pressure cancellation structure, an appropriate force acts on the first valve body 40 in the valve closing direction, and the valve closed state can be stably maintained.

[0062] Even when the first valve body 40 starts to open, the clearance between the first valve body 40 and the tip of the first valve body 40 is affected by the upstream pressure P1 while the tip of the first valve body 40 is positioned inside the straight portion 168 of the first valve hole 30 (FIGS. 7B and 7C). For this reason, the pressure-receiving diameter φB changes very little. As a result, the pressure-receiving diameter difference (φA-φB) remains small, so the effect of the pressure difference (P1-P2), that is, the increase in the load in the valve-closing direction, is suppressed.

[0063] When the tip of the first valve body 40 leaves the straight portion 168, the pressure-receiving diameter φB gradually decreases, but the change is gradual while the tip is located inside the second tapered surface 166 (FIG. 7(D)). In addition, since the opening of the first valve 2 increases and the pressure difference (P1-P2) itself decreases, an increase in the load in the valve closing direction is suppressed.

[0064] In contrast, in Comparative Example 2, the first valve hole 230 does not have a straight portion as in this embodiment, and therefore the influence of the upstream pressure P1 is less likely to remain. That is, as the opening degree of the first valve body 40 increases immediately after the valve opening operation begins, the pressure-receiving diameter φB decreases (FIGS. 8(A) to (D)), and the pressure-receiving diameter difference (φA-φB) increases. As a result, the load in the valve closing direction increases without waiting for the pressure difference (P1-P2) to decrease. This increases the load on the motor when the first valve 202 is open.

[0065] FIG. 9 is a diagram showing changes in the load in the valve closing direction that the first valve body 40 receives in response to a valve opening operation. The horizontal axis of the figure indicates the stroke of the first valve body 40 in the valve opening direction, and the vertical axis indicates the load that the first valve body 40 receives in the valve closing direction. The "load" here refers to the load acting on the first valve body 40 due to the pressure difference (P1-P2), and this figure shows the results of analyzing that load. In the figure, the solid line indicates the analysis results of this embodiment, and the dashed dotted line indicates the analysis results of Comparative Example 2.

[0066] From this analysis result, it is found that according to this embodiment, the increase in the load when the first valve starts to open can be suppressed and the peak of the load can be reduced compared to Comparative Example 2. This is considered to be due to the above-mentioned differential pressure reduction effect. It is also found that when the valve leaves the partially open state, the differential pressure (P1-P2) itself becomes smaller, so the load becomes smaller.

[0067] As described above, in this embodiment, the cross-sectional shape of the seal ring 124 is a right-angled triangle, one apex of which is in close contact with the guide hole 38, while the flat surfaces of the seal ring 124 and the low-pressure side surface 144 of the seal accommodating portion 122 are in contact with each other. This makes the contact area between the seal ring 124 and the guide hole 38 smaller than the contact area between the low-pressure side surface 144 of the seal accommodating portion 122 and the seal ring 124. With this configuration, the sliding resistance can be reduced while ensuring the sealing between the first valve body 40 and the guide hole 38. As a result, the rotational torque of the motor unit 8 can be reduced. In addition, the deformation of the seal ring 124 can be suppressed, and the first valve body 40 can be stably slid along the guide hole 38.

[0068] In addition, in this embodiment, the opening and closing structure of the first valve 2 includes an insertion / removal structure in which the tip of the first valve body 40 is inserted and removed from the first valve hole 30, and an attachment / detachment structure in which the edge of the first valve body 40 is attached and detached to the tapered surface of the first valve seat 32. That is, by providing a straight portion 168 in the first valve hole 30 near the first valve seat 32, a minute clearance is formed between the tip of the first valve body 40 and the first valve hole 30 when the first valve 2 is in the closed and slightly open states. This makes it possible to suppress the change in the pressure-receiving diameter of the first valve body 40 when the valve is opened, and to reduce the load acting on the first valve body 40 in the closing direction. As a result, the load on the motor can be suppressed. In this embodiment, the load in the closing direction is the largest when the valve is opened, but since this can be suppressed, it is also possible to reduce the size of the motor unit 8.

[0069] Furthermore, in this embodiment, for the large-diameter first valve 2, the rubber 162 is baked so as to include the position of the first valve seat 32. Therefore, when the first valve 2 is closed, the rubber is appropriately deformed, thereby improving the sealing performance of the valve portion. In other words, the required valve closing performance can be obtained without particularly increasing the load of the motor unit 8. As a result, the load on the motor unit 8 can be reduced. Also, by increasing the thickness of the rubber 162 at the position of the first valve seat 32, the durability of the first valve seat 32 can be improved.

[0070] Although a preferred embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to that specific embodiment, and various modifications are possible within the scope of the technical concept of the present invention.

[0071] [Variations] 10A to 10C are partial enlarged views showing the structure of a seal ring according to modified examples, in which Fig. 10A shows modified example 1, Fig. 10B shows modified example 2, and Fig. 10C shows modified example 3. The seal rings according to these modifications all have a polygonal cross section. In all modifications, the contact area between the seal ring and the guide hole is smaller than the contact area between the seal ring and the low pressure side surface of the seal receiving portion.

[0072] Seal ring 310 of modification 1 has a stepped rectangular cross section, with the outer diameter of the upper part being smaller than that of the lower part (FIG. 10(A)). That is, seal ring 310 has small diameter part 312 (upper part) and large diameter part 314 (lower part), and large diameter part 314 slides in guide hole 38. By leaving small diameter part 312, the rigidity of seal ring 310 is ensured, while by limiting the sliding part to large diameter part 314, sliding resistance can be kept small.

[0073] Seal ring 320 of modification 2 corresponds to large diameter portion 314 of modification 1, and has a rectangular cross section with a small height (FIG. 10(B)). Even with this configuration, the sliding area with guide hole 38 is small, so that sliding resistance can be kept small.

[0074] Seal ring 330 of modification 3 has a generally diamond-shaped cross section with the outer and inner circumferential portions projecting slightly in the radial direction. An annular groove having a shape complementary to the lower surface of seal ring 330 is formed on low-pressure side surface 334 of seal accommodating portion 322. By making it diamond-shaped, it has a cross-sectional area similar to that of modification 1, and rigidity can be ensured. In addition, by making the lower surface of seal ring 330 and low-pressure side surface 334 have complementary shapes, seal ring 330 can be stably held and good sealing performance can be ensured.

[0075] Figure 11 is a partially enlarged view showing the structure of a seal ring according to another modified example. Figure 11(A) shows modified example 4, and Figure 11(B) shows modified example 5. In each figure, the upper part shows a state in which no differential pressure acts on the seal ring, and the lower part shows a schematic diagram of the behavior when a differential pressure acts on the seal ring.

[0076] The seal ring 340 of the fourth modification has a cross section of an equilateral triangle with a rounded apex (upper part of FIG. 11(A)). The upper surface 342 and the lower surface 344 of the seal ring 340 are inclined surfaces (tapered surfaces). When a differential pressure (P1-P2) acts on the seal ring 340, the axial component of the differential pressure acts downward (lower part of FIG. 11(A)). Therefore, a rotational moment or a bending moment acts on the cross section of the seal ring 340 (see the two-dot chain line arrow). As a result, the cross section of the seal ring 340 is deformed. The contact area between the seal ring 340 and the guide hole 38 is smaller than the contact area between the low pressure side surface 144 of the seal accommodating portion 122 and the seal ring 340. This allows the first valve body 40 to slide stably along the guide hole 38 while suppressing the sliding resistance thereof to be small.

[0077] The seal ring 350 of the fifth modification is obtained by turning the seal ring 124 of the above embodiment upside down, and has a right-angled triangular cross section (upper part of FIG. 11(B)). When a pressure difference (P1-P2) acts on the seal ring 350, the axial component of the pressure difference acts downward (lower part of FIG. 11(B)). Therefore, as in the fourth modification, a rotational moment or bending moment acts on the cross section of the seal ring 350 (see the two-dot chain line arrow). As a result, the contact area between the seal ring 350 and the guide hole 38 is smaller than the contact area between the low pressure side surface 144 of the seal accommodating portion 122 and the seal ring 350. This allows the first valve body 40 to slide stably along the guide hole 38 while keeping the sliding resistance small.

[0078] Fig. 12 shows the results of an analysis of the deformation of the seal ring due to a pressure difference. Fig. 12(A) shows the analysis results of Modification 4, and Fig. 12(B) shows the analysis results of Modification 5. In each figure, the pressure difference (P1-P2) increases from the top to the bottom.

[0079] This analysis shows that in Modification 4, the pressure difference causes deformation of seal ring 340, and the contact area of ​​seal ring 340 with guide hole 38 becomes smaller than the contact area with low pressure side 144. The sliding surface pressure (sliding resistance) after deformation of seal ring 340 is also kept low (FIG. 12(A)). Similarly, in Modification 5, the pressure difference causes deformation of seal ring 350, and the contact area of ​​seal ring 350 with guide hole 38 becomes smaller than the contact area with low pressure side 144. The sliding surface pressure (sliding resistance) after deformation of seal ring 350 is also kept low (FIG. 12(B)).

[0080] Fig. 13 is a partial enlarged view showing a seal structure according to another modified example, in which Fig. 13(A) is a partial enlarged cross-sectional view showing the configuration of a seal ring and its surroundings, and Fig. 13(B) is an enlarged view of part D in Fig. 13(A).

[0081] 13(A), in this modification, seal accommodating portion 422 is provided on the inner circumferential surface of guide hole 438 rather than on the outer circumferential surface of first valve body 440, and seal ring 424 is fitted into it. As also shown in FIG 13(B), seal accommodating portion 422 is an annular recess having a bottom surface 441, a high pressure side surface 442, and a low pressure side surface 444.

[0082] On the other hand, the seal ring 424 has a cross section of a right-angled triangle with a rounded apex. The outer peripheral surface 446 of the seal ring 424 is flat, and a lower surface 448 that is perpendicular to the outer peripheral surface 446 abuts against the low-pressure side surface 444 of the seal accommodating portion 422. The upper surface 450 of the seal ring 424 is inclined (tapered), and an inner peripheral surface 452 of the seal ring 424 is formed by a top portion where the upper surface 450 and the lower surface 448 are connected. When the first valve body 440 slides along the guide hole 438, the outer peripheral surface of the first valve body 440 slides closely against the inner peripheral surface 452 of the seal ring 424, thereby ensuring sealing performance. A gap S is formed between the bottom surface 441 of the seal accommodating portion 422 and the outer peripheral surface 446 of the seal ring 424 (between the opposing surfaces of the bottom surface 441 and the seal ring 424).

[0083] Even in such a configuration, the contact area of ​​seal ring 424 with the outer circumferential surface of first valve body 440 is smaller than the contact area with low pressure side surface 444 of seal accommodating portion 422. That is, compared to the case of an O-ring or the like, the sliding area between seal ring 424 and first valve body 440 can be made smaller, and the sliding resistance of first valve body 440 can be reduced.

[0084] Figure 14 is a partial enlarged view showing the configuration of a first valve according to another modified example, Figure 14(A) is a partial enlarged cross-sectional view showing the configuration of the first valve and its surroundings, and Figure 14(B) is an enlarged view of part F in Figure 14(A).

[0085] As shown in Fig. 14(A), in this modification, the attachment / detachment structure between the first valve body 540 and the valve seat forming member 528 in the first valve 502 is different from that of the above embodiment. As also shown in Fig. 14(B), the upper end opening of the valve seat forming member 28 forms an edge portion 574, which constitutes the first valve seat 532. Meanwhile, the tip portion of the first valve body 540 has a tapered surface 564 and a straight portion 568. The straight portion 568 is parallel to the axis of the first valve body 540.

[0086] That is, the first valve 502 has, as its opening / closing structure, an insertion / removal structure in which the straight portion 568 is coaxially inserted into and removed from the first valve hole 530, and a detachment structure in which the tapered surface 564 is attached to and detached from the edge portion 574 in a state in which the straight portion 568 is inserted into the first valve hole 530. As a result, a minute clearance is formed between the tip portion of the first valve body 540 and the first valve hole 530 when the first valve 502 is in the closed and slightly open states.

[0087] Therefore, similarly to the above embodiment, it is possible to suppress a decrease in the pressure-receiving surface area immediately after the first valve body 540 opens. As a result, it is possible to reduce the load acting on the first valve body 540 in the valve closing direction, and to suppress the load on the motor.

[0088] Although not shown in the present modified example, at least the tapered surface 564 of the first valve body 540 may be subjected to rubber baking. Also, at least the edge portion 574 of the valve seat forming member 528 and its vicinity may be subjected to rubber baking. This can increase the durability of the first valve seat 532 and improve the sealing performance of the first valve 502.

[0089] [Other variations] In the above embodiment and modified example, the cross-sectional shape of the seal ring is exemplified, but a cross-sectional polygonal shape other than the above may be adopted. However, the seal ring is fitted into an annular recess provided on one of the outer peripheral surface of the valve body and the inner peripheral surface of the guide hole, so that the contact area between the other of the outer peripheral surface of the valve body and the inner peripheral surface of the guide hole is smaller than the contact area with the low pressure side of the seal accommodating portion (recess). The contact area between the other of the outer peripheral surface of the valve body and the inner peripheral surface of the guide hole may be smaller than the contact area with the low pressure side of the recess due to the pressure difference.

[0090] In the above embodiment, a two-stage tapered structure is exemplified for the first valve hole 30, but a structure having a single taper and a straight portion may also be used. Specifically, a structure having the first tapered surface 164 shown in FIG. 4(B) but not the second tapered surface 166 may be adopted.

[0091] In the above embodiment, a composite valve having multiple valves (first valve and second valve) arranged coaxially has been exemplified. In a modified example, a motor-operated valve having a single valve may be used. In this case, too, the seal ring is fitted into an annular recess provided on one of the outer circumferential surface of the valve body and the inner circumferential surface of the guide hole, so that the contact area between the outer circumferential surface of the valve body and the inner circumferential surface of the guide hole, and the other, is made smaller than the contact area with the low-pressure side of the seal accommodating portion (recess).

[0092] In the above embodiment, the spring 58 is exemplified as the biasing member that biases the first valve body 40 in the valve closing direction, but rubber or other elastic bodies may also be used.

[0093] In the above embodiment, the stator includes a yoke having pole teeth. In a modified example, the stator may include a laminated core.

[0094] In the above embodiment, the motor-operated valve is configured as an expansion valve, but any control valve such as an on-off valve or a solenoid valve that does not have an expansion function may be used. Also, in the above embodiment, a motor is exemplified as an actuator, but a solenoid or other actuator may be used.

[0095] The motor-operated valve of the above embodiment is preferably applied to a refrigeration cycle that uses a refrigerant such as an alternative fluorocarbon (HFC-134a) as a refrigerant, but can also be applied to a refrigeration cycle that uses a refrigerant with a high operating pressure such as carbon dioxide. In that case, an external heat exchanger such as a gas cooler is disposed in the refrigeration cycle instead of the condenser.

[0096] In the above embodiment, the motor-operated valve is applied to the refrigeration cycle of an air conditioner for an automobile, but the motor-operated valve may be applied to any air conditioner equipped with an electric expansion valve, not limited to vehicles. The motor-operated valve may also be configured as a motor-operated valve for controlling the flow of a fluid other than a refrigerant, such as in a hot water supply device or a hydraulic control device.

[0097] The present invention is not limited to the above-mentioned embodiment and modified examples, and the components can be modified without departing from the gist of the present invention. Various inventions can be formed by appropriately combining multiple components disclosed in the above-mentioned embodiment and modified examples. In addition, some components can be deleted from all the components shown in the above-mentioned embodiment and modified examples. [Explanation of symbols]

[0098] 1 motor-operated valve, 2 first valve, 4 second valve, 6 valve body, 8 motor unit, 10 body, 16 guide member, 18 inlet port, 20 outlet port, 28 valve seat forming member, 30 first valve hole, 32 first valve seat, 38 guide hole, 40 first valve body, 42 internal passage, 44 second valve hole, 46 second valve seat, 48 operating rod, 50 second valve body, 60 rotor, 62 rotating shaft, 64 stator, 90 screw feed mechanism, 108 back pressure chamber, 110 valve chamber, 112 operating connecting member, 122 seal accommodating portion, 124 seal ring, 126 enlarged diameter portion, 130 communication hole, 132 inlet port, 134 downstream passage, 136 outlet port, 140 bottom surface, 142 high pressure side, 144 low pressure side, 146 Inner peripheral surface, 152 Outer peripheral surface, 162 Rubber, 164 First tapered surface, 166 Second tapered surface, 168 Straight portion, 170 Step portion, 172 Small diameter portion, 174 Edge portion, 202 First valve, 224 O-ring, 230 First valve hole, 310 Seal ring, 312 Small diameter portion, 314 Large diameter portion, 320 Seal ring, 322 Seal accommodating portion, 330 Seal ring, 334 Low pressure side, 340 Seal ring, 350 Seal ring, 422 Seal accommodating portion, 424 Seal ring, 438 Guide hole, 440 First valve body, 442 High pressure side, 444 Low pressure side, 446 Outer peripheral surface, 452 Inner peripheral surface, 502 First valve, 528 Valve seat forming member, 530 First valve hole, 532 First valve seat, 540 First valve body, 564 tapered surface, 568 straight portion, 574 edge portion, S gap.

Claims

1. a body having a valve hole and a guide hole coaxially therewith; a valve body that is slidably supported in the guide hole and moves toward and away from the valve hole to open and close the valve portion; a seal ring that is fitted into an annular recess that is provided on one of an outer circumferential surface of the valve body and an inner circumferential surface of the guide hole, and that prevents leakage of the refrigerant from the high pressure side to the low pressure side through a gap between the valve body and the guide hole; Equipped with a contact area between the seal ring and the other of an outer circumferential surface of the valve body and an inner circumferential surface of the guide hole is smaller than a contact area between the seal ring and the low-pressure side of the recess when a pressure difference between the high-pressure side and the low-pressure side is applied; A control valve, comprising: a gap formed between a bottom surface of the recess and an opposing surface of the seal ring.

2. 2. The control valve according to claim 1, wherein the seal ring has an opposing surface having a shape complementary to the low pressure side surface of the recess.

3. 3. The control valve according to claim 1, wherein the seal ring has a polygonal cross section.

4. 4. The control valve according to claim 3, wherein the seal ring has a triangular cross section, one vertex of which abuts against the other of the outer circumferential surface of the valve body and the inner circumferential surface of the guide hole.

5. 5. A control valve according to claim 1, wherein the width of the recess is made larger than the axial width of the seal ring, and the pressure difference causes the seal ring to adhere to the low-pressure side of the recess.

6. A back pressure chamber is formed on the valve body on the opposite side to the valve hole.

6. The control valve according to claim 1, wherein a communication passage is provided that communicates between the upstream side of the valve hole and the back pressure chamber, so that at least a portion of the fluid pressure acting on the valve body is canceled.

7. a body having a valve hole and a guide hole coaxially therewith; a valve body that is slidably supported in the guide hole and moves toward and away from the valve hole to open and close the valve portion; a seal ring that is fitted into an annular recess that is provided on one of an outer circumferential surface of the valve body and an inner circumferential surface of the guide hole, and that prevents leakage of the refrigerant from the high pressure side to the low pressure side through a gap between the valve body and the guide hole; Equipped with The cross section of the seal ring has a shape in which a rotational moment or a bending moment acts due to a pressure difference between a high pressure side and a low pressure side, a pressure difference between the high pressure side and the low pressure side of the seal ring and a contact area between the seal ring and the other of the outer peripheral surface of the valve body and the inner peripheral surface of the guide hole, the contact area being smaller than the contact area with the low pressure side of the recess.

Images