Flow path switching valve

Abstract

To provide a passage switching valve which can secure stable driving of a valve body regardless of a valve opening.SOLUTION: A passage switching valve includes: a valve body; a valve shaft housed in the valve body so as to be movable in an axial direction of the valve body; a first valve body unit attached to the valve shaft and including a first valve body which may contact with a first valve seat; and a second valve body unit attached to the valve shaft and including a second valve body which may contact with the second valve seat. In the valve body, a first pressure equalization chamber is formed at the opposite side of a valve chamber across the first valve body unit and a second pressure equalization chamber is formed at the opposite side of the valve chamber across the second valve body unit. The first valve body unit is formed with a first communication opening which allows communication between the first pressure equalization chamber and the valve chamber. The second valve body unit is formed with a second communication opening which allows communication between the second pressure equalization chamber and the valve chamber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a flow path switching valve.

Background Art

[0002] As an example of a flow path switching valve, Patent Document 1 discloses a flow path switching valve capable of reducing the load acting on a valve body during flow path switching, reducing the driving torque of the valve body, and achieving miniaturization, increased capacity, power saving, etc.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the flow path switching valve of Patent Document 1, an equalizing passage is formed that communicates a back pressure chamber defined above an upper valve body and a lower space formed below a lower valve body by a through hole penetrating the connecting shaft in the axial direction. By means of such an equalizing passage, the internal pressure of the back pressure chamber and the internal pressure of the lower space can be made equal, whereby the force applied to the upper valve body according to the internal pressure of the back pressure chamber and the force applied to the lower valve body according to the internal pressure of the lower space can be balanced.

[0005] However, in the configuration of Patent Document 1, when the valve opening degree is large, a phenomenon occurs in which valve body driving becomes unstable. In response to this, as a result of intensive research by the present inventors, due to the flow of fluid from the inlet of the flow path switching valve toward the first outlet or the second outlet, a pressure difference occurs between the vicinity of the upper valve body and the vicinity of the lower valve body in the valve chamber, and the axial force applied to the upper valve body and the lower valve body changes due to the pressure difference, and it has been found that the balance of the axial forces applied to the upper valve body and the lower valve body is lost.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a flow path switching valve capable of ensuring stable valve body drive regardless of the valve opening degree.

Means for Solving the Problems

[0007] The flow path switching valve of the present invention includes a valve body including a first flow path communicating with a valve chamber, a second flow path and a third flow path communicating with the valve chamber, a first valve seat formed between the valve chamber and the second flow path, and a second valve seat formed between the valve chamber and the third flow path, a valve shaft movably accommodated in the valve body in the axial direction of the valve body, a first valve body unit attached to the valve shaft and having a first valve body capable of contacting the first valve seat, a second valve body unit attached to the valve shaft and having a second valve body capable of contacting the second valve seat, a first pressure equalizing chamber is formed on the opposite side of the valve chamber with respect to the first valve body unit across the first valve body unit, and a second pressure equalizing chamber is formed on the opposite side of the valve chamber with respect to the second valve body unit across the second valve body unit, a first communication opening communicating the first pressure equalizing chamber and the valve chamber is formed in the first valve body unit, a second communication opening communicating the second pressure equalizing chamber and the valve chamber is formed in the second valve body unit 、 It has a hollow cylindrical first closing member attached to one end of the valve body in the axial direction, and a hollow cylindrical second closing member attached to the other end of the valve body in the axial direction. The first pressure equalizing chamber is formed inside the first closing member, and the second pressure equalizing chamber is formed inside the second closing member. The first valve body unit has a first sealing portion that abuts against and seals the inner circumference of the first closing member. The second valve body unit has a second sealing portion that abuts against and seals the inner circumference of the second closing member. When the first valve body is separated from the first valve seat, the inner diameter of the position where the first sealing portion abuts against the first closing member is larger than the inner diameter of the position where the first sealing portion abuts against the first closing member when the first valve body is seated on the first valve seat. When the second valve body is separated from the second valve seat, the inner diameter of the position where the second sealing portion abuts against the second closing member is larger than the inner diameter of the position where the second sealing portion abuts against the second closing member when the second valve body is seated on the second valve seat. It is characterized by the above. The flow path switching valve of the present invention A valve body including a first flow path communicating with the valve chamber, a second flow path and a third flow path communicating with the valve chamber, a first valve seat formed between the valve chamber and the second flow path, and a second valve seat formed between the valve chamber and the third flow path. A valve shaft movably accommodated in the valve body in the axial direction of the valve body. A first valve body unit attached to the valve shaft and including a first valve body capable of abutting against the first valve seat. A second valve body unit attached to the valve shaft and including a second valve body capable of abutting against the second valve seat. A first pressure equalizing chamber is formed in the valve body on the side opposite to the valve chamber with the first valve body unit interposed therebetween, and a second pressure equalizing chamber is formed on the side opposite to the valve chamber with the second valve body unit interposed therebetween. A first communication opening communicating the first pressure equalizing chamber and the valve chamber is formed in the first valve body unit. A second communication opening communicating the second pressure equalizing chamber and the valve chamber is formed in the second valve body unit. It has a hollow cylindrical first closing member attached to one end of the valve body in the axial direction, and a hollow cylindrical second closing member attached to the other end of the valve body in the axial direction. The first pressure equalizing chamber is formed inside the first closing member, and the second pressure equalizing chamber is formed inside the second closing member. The first valve body unit has a first sealing portion that abuts against and seals the inner circumference of the first closing member. The second valve body unit has a second seal portion that abuts against the inner circumference of the second closing member to seal. The first seal portion has a communication hole corresponding to the first communication opening, and the second seal portion has a communication hole corresponding to the second communication opening, which is characterized by this.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a flow path switching valve capable of ensuring stable valve body driving regardless of the valve opening degree.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0010] Hereinafter, a flow path switching valve according to an embodiment of the present invention will be described with reference to the drawings. In this specification, the drive device side is taken as the upper side, and the opposite side is taken as the lower side.

[0011] (First Embodiment) FIG. 1 is a longitudinal sectional view of a flow path switching valve 1 according to the first embodiment, showing a state in which an inlet flow path (first flow path) and a first outlet flow path (second flow path) communicate, and FIG. 2 is a longitudinal sectional view of the flow path switching valve 1 according to the first embodiment, showing a state in which the inlet flow path and a second outlet flow path (third flow path) communicate. Let the axis of the flow path switching valve 1 be L. In this embodiment, the fluid flowing in from the first flow path is switched by the flow path switching valve 1 and discharged from the second flow path or the third flow path. However, in the reverse flow, either the fluid flowing in from the second flow path or the third flow path may be discharged from the first flow path by switching the flow path switching valve 1.

[0012] As shown in the figure, the flow path switching valve 1 of this embodiment is a three-way switching valve, and includes a valve body 10, a valve shaft 20, a first valve body unit 30, a second valve body unit 40, and a drive device 50.

[0013] The valve body 10 includes a valve housing 11, a first closing member 12, a second closing member 13, and a lid member 14.

[0014] The valve housing 11 is formed by connecting a main body 11a, an inlet tubular portion 11b, a first outlet tubular portion 11c, and a second outlet tubular portion 11d, each of which is cylindrical.

[0015] The main body 11a is formed by connecting an upper cylindrical portion 11e with an open upper end, a lower cylindrical portion 11f with an open lower end, and an intermediate cylindrical portion 11g having a smaller diameter than the upper cylindrical portion 11e and the lower cylindrical portion 11f and coaxially connecting them.

[0016] At the joint between the intermediate cylindrical portion 11g and the upper cylindrical portion 11e, an upper short circular tube portion 11h is formed such that the inner edge of the intermediate cylindrical portion 11g protrudes toward the upper cylindrical portion 11e side. The tip of the upper short circular tube portion 11h constitutes the first valve seat 11i. The inside of the intermediate cylindrical portion 11g constitutes the valve chamber VC. The first valve seat 11i is formed between the valve chamber VC and the first outlet flow path.

[0017] At the joint between the intermediate cylindrical portion 11g and the lower cylindrical portion 11f, a lower short circular tube portion 11j is formed such that the inner edge of the intermediate cylindrical portion 11g protrudes toward the lower cylindrical portion 11f side. The tip of the lower short circular tube portion 11j constitutes the second valve seat 11k. The second valve seat 11k is formed between the valve chamber VC and the second outlet flow path.

[0018] The inlet tubular portion 11b extends in a direction perpendicular to the axis L from the intermediate cylindrical portion 11g, and the inlet flow path formed therein communicates with the valve chamber VC.

[0019] The first outlet tubular portion 11c extends in a direction perpendicular to the axis L on the opposite side of the axis L from the inlet tubular portion 11b across the axis L of the valve body 10 from the upper cylindrical portion 11e, and the first outlet flow path formed therein communicates with the valve chamber VC.

[0020] The second outlet tubular portion 11d extends in a direction perpendicular to the axis L on the opposite side of the axis L from the inlet tubular portion 11b across the axis L of the valve body 10 from the lower cylindrical portion 11f, and the second outlet flow path formed therein communicates with the valve chamber VC. It is preferable that the distance between the axis of the inlet tubular portion 11b and the axis of the first outlet tubular portion 11c is equal to the distance between the axis of the inlet tubular portion 11b and the axis of the second outlet tubular portion 11d.

[0021] The solid cylindrical valve shaft 20 is coaxially formed by connecting an upper shaft 21, an intermediate shaft 22, and a lower shaft 23 in series. The valve shaft 20 has a first valve body unit 30 and a second valve body unit 40 attached to both ends thereof, and these are integrally movable in the axial direction.

[0022] The hollow cylindrical first closing member 12 is formed by connecting a diameter-expanded portion 12a, an intermediate portion 12b having a smaller diameter than the diameter-expanded portion 12a, and an annular portion 12c protruding downward from the lower end of the intermediate portion 12b. In the present embodiment, the inner diameters (inner circumferences of the cylinder) of the diameter-expanded portion 12a, the intermediate portion 12b, and the upper half of the annular portion 12c, with which the sealing body 32a of the first seal portion 32 to be described later always abuts, are equal.

[0023] On the other hand, the inner diameter of the lower half of the annular portion 12c is tapered so as to expand downward. The first closing member 12 is inserted into the upper cylindrical portion 11e of the valve housing 11 from above, and is attached to the upper end of the valve housing 11 by fitting while abutting the step portion between the diameter-expanded portion 12a and the intermediate portion 12b against the step of the upper end opening of the upper cylindrical portion 11e of the valve housing 11.

[0024] FIG. 3A is a cross-sectional view showing an enlarged periphery of the first valve body unit 30, and shows a state of being seated on the first valve seat 11i. The first valve body unit 30 includes a cylindrical first main body 31, a first seal portion 32, a first seal retainer 33, a first valve body 34, and a first seat 35.

[0025] The first main body 31 has a small-diameter portion 31a that fits inside the inner circumference of the first closing member 12 and is slidable in the axial direction, a large-diameter portion 31b that has a larger diameter than the small-diameter portion 31a and is connected to the lower end of the small-diameter portion 31a, and a thin-walled cylindrical caulking portion 31c that is connected to the lower end of the large-diameter portion 31b.

[0026] The annular first valve body 34, together with the first seat 35 that is annular and has a smaller diameter than the first valve body 34, is inserted into the caulking portion 31c that is cylindrical before caulking from below. Thereafter, by plastically deforming the lower end of the caulking portion 31c to expand the diameter by caulking, the first valve body 34 is fixed to the first main body 31 via the first seat 35. At this time, the outer side in the radial direction of the first valve body 34 is exposed from the first seat 35, and its lower surface faces the first valve seat 11i of the valve housing 11.

[0027] The small-diameter portion 31a and the large-diameter portion 31b coaxially have a large-diameter opening 31d with an inner diameter equal to the minimum inner diameter of the caulking portion 31c, and a small-diameter opening 31e communicating with the large-diameter opening 31d. Further, a first pressure equalizing hole 31f extending from the upper end of the large-diameter opening 31d toward the upper end of the first main body 31 is formed in parallel with the small-diameter opening 31e.

[0028] The first seal portion 32 installed at the upper end of the first main body 31 has a seal body 32a made of resin and having flexibility, and a metallic leaf spring 32b. The seal body 32a and the leaf spring 32b have central holes 32c, 32d corresponding to the small-diameter opening 31e, and communication holes 32e, 32f corresponding to the first pressure equalizing hole 31f.

[0029] The annular first seal retainer 33 having a smaller diameter than the first main body 31 has a central hole 33a corresponding to the small-diameter opening 31e and a communication hole 33b corresponding to the first pressure equalizing hole 31f.

[0030] The first seal portion 32 is installed at the upper end of the first main body 31, and the first seal retainer 33 is installed so as to abut on the upper surface of the first seal portion 32.

[0031] The intermediate shaft 22 of the valve shaft 20 is inserted into the large-diameter opening 31d of the first main body 31, and its upper end abuts on the step portion between the small-diameter opening 31e and the large-diameter opening 31d. Further, the upper shaft 21 penetrates the small-diameter opening 31e, the central holes 32c, 32d of the seal body 32a and the leaf spring 32b, and the central hole 33a of the first seal retainer 33, and protrudes above the first valve body unit 30. A first buffer chamber BF1 is formed between the large-diameter opening 31d and the intermediate shaft 22.

[0032] A thin-walled cylindrical caulking portion 21a is formed at the protruding upper end of the upper shaft 21. By plastically deforming the upper end of the caulking portion 21a to expand its diameter by caulking, the first seal portion 32 is fixed to the first main body 31 via the first seal retainer 33. In addition, in order to make it relatively easy to insert when assembling the first seal portion 32 to the first closing member 12, the lower half of the annular portion 12c is tapered.

[0033] As shown in FIG. 3A, when the first valve body unit 30 is attached to the first closing member 12, the outer edge of the seal body 32a is bent upward and abuts against the inner circumference of the first closing member 12 over the entire circumference to suppress fluid leakage. Further, the radially outer end portion bent upward of the leaf spring 32b abuts against the radially inner side of the bent outer edge of the seal body 32a and acts to urge the seal body 32a toward the inner circumference of the first closing member 12. In the present embodiment, within the range where the seal body 32a of the first seal portion 32 that moves together with the first valve body unit 30 can abut, the inner diameter of the first closing member 12 is equal. Note that, as the first seal portion 32, for example, those disclosed in Japanese Patent Application Laid-Open No. 2017-223293 can be used, and thus detailed description thereof is omitted.

[0034] The space inside the first closing member 12 sealed by the first seal portion 32 is referred to as the first equal pressure chamber EC1. The upper part of the first equal pressure chamber EC1 formed on the side opposite to the valve chamber VC with the first valve body unit 30 interposed therebetween is shielded by a drive device 50 described later. The first equal pressure chamber EC1 communicates with the valve chamber VC via a first equal pressure hole 31f, communication holes 32e and 32f, and a communication hole 33b. The first equal pressure hole 31f, the communication holes 32e and 32f, and the communication hole 33b are referred to as a first communication opening.

[0035] Here, let the inner diameter of the first closing member 12 be A, and the inner diameter of the first valve port, which is the inner circumference of the upper short cylindrical portion 11h, be C. The inner diameter A of the first closing member 12 is equal to the inner diameter C of the first valve port. Therefore, the cross-sectional area in the direction orthogonal to the axis of the first equal pressure chamber EC1 is equal to the cross-sectional area in the direction orthogonal to the axis of the first valve port. Further, when the first valve body 34 seats on the first valve seat 11i, let the axial distance from the first valve seat 11i to the upper end of the large-diameter opening 31d be B. That is, the first communication opening and the first valve seat 11i are separated from each other by a distance B with the first buffer chamber BF1 interposed therebetween.

[0036] In FIG. 1, the hollow cylindrical second closing member 13 is inserted into the lower cylindrical portion 11f of the valve housing 11 from below, and its upper end is abutted against an inner peripheral step 11m formed at an intermediate position of the lower cylindrical portion 11f, and it is attached to the lower end of the valve housing 11. The second closing member 13 coaxially has an annular groove 13a on its lower surface, and in a state of being attached to the lower cylindrical portion 11f, the lower end of the second closing member 13 and the lower end of the lower cylindrical portion 11f are in the same axial position.

[0037] The lid member 14 has an annular plate portion 14a, a bottomed cylindrical portion 14b connected to the inner edge of the annular plate portion 14a, and a thin cylindrical portion 14c coaxially formed on the upper surface of the annular plate portion 14a.

[0038] FIG. 3B is a cross-sectional view showing an enlarged periphery of the second valve body unit 40, and shows a state of being separated from the second valve seat 11k. The second valve body unit 40 has a cylindrical second main body 41, a second seal portion 42, a second seal retainer 43, a second valve body 44, and a second seat 45, and has substantially the same configuration except that it has an upside-down relationship with the first valve body unit 30 in the vertical direction, so redundant description is omitted.

[0039] The difference between the second valve body unit 40 and the first valve body unit 30 is that a caulking cylindrical portion 41g is continuously provided at the center of the lower end of the second main body 41. After attaching the second seal portion 42 and the second seal retainer 43 to the second main body 41 so that the caulking cylindrical portion 41g penetrates therethrough, the lower end of the caulking cylindrical portion 41g is plastically deformed by caulking to expand its diameter, whereby the second seal portion 42 is fixed to the second main body 41 via the second seal retainer 43. The lower shaft 23 of the valve shaft 20 is inserted into the second valve body unit 40. A second buffer chamber BF2 is formed between the large-diameter opening 41d of the second main body 41 and the intermediate shaft 22.

[0040] In the assembled state, the second seal portion 42 seals between the inner circumference of the second closing member 13. In the range where the seal body of the second seal portion 42 that moves together with the second valve body unit 40 can abut, the inner diameter of the second closing member 13 is equal. The second main body 41 is slidably fitted in the axial direction to the inner circumference of the second closing member 13. While fitting the thin-walled cylindrical portion 14c into the annular groove 13a, the lid member 14 is attached to the lower end of the second closing member 13. At this time, the coil spring 15 is disposed between the lid member 14 and the second seal retainer 43 of the second valve body unit 40, and biases the second valve body unit 40 upward with respect to the lid member 14.

[0041] The space surrounded by the second valve body unit 40, the hollow cylindrical second closing member 13, and the lid member 14 is called the second pressure equalizing chamber EC2. The second pressure equalizing chamber EC2 formed on the opposite side of the valve chamber VC with the second valve body unit 40 interposed therebetween communicates with the valve chamber VC through the second pressure equalizing hole 41f of the second main body 41, the communication hole of the second seal portion 42, and the communication hole 43b of the second seal retainer 43. The second pressure equalizing hole 41f, the communication hole of the second seal portion 42, and the communication hole 43b are called the second communication opening.

[0042] The radially outer side of the second valve body 44 of the second valve body unit 40 is exposed from the second seat 45, and its upper surface is in a state facing the second valve seat 11k of the valve housing 11. The inner diameter of the second closing member 13 is equal to the inner diameter of the second valve port which is the inner circumference of the second valve seat 11k. That is, the cross-sectional area in the direction orthogonal to the axis of the second pressure equalizing chamber EC2 is equal to the cross-sectional area in the direction orthogonal to the axis of the second valve port. In the whole of the second closing member 13 including the range where the seal portion of the second seal portion 42 always abuts, its inner diameter is equal.

[0043] The drive device (drive portion) 50 is an electromagnetic actuator, is disposed above the valve main body 10, and closes the upper end of the first pressure equalizing chamber EC1. The drive device 50 has a can 51 (a cylindrical member with a bottom), an armature 52, a plunger 53, a coil 54, a compression coil spring 55, and a resin case 56 that houses these. Note that the drive device 50 may drive the valve shaft 20 in the direction of the axis L using an electric motor or a solenoid.

[0044] The lower end of the can 51 formed in a toped cylindrical shape is attached near the upper end of the attractor 52. The attractor 52 having a lower opening 52a is attached to the upper end of the first closing member 12.

[0045] The plunger 53 slidably disposed within the can 51 has an upper opening 53a. A drive shaft 57, the upper end of which is fitted and fixed to the upper opening 53a, is disposed so as to penetrate the lower opening 52a and is configured to move integrally with the plunger 53. The lower end of the drive shaft 57 has an enlarged diameter and protrudes downward from the attractor 52 so as to be able to contact the upper surface of the first seal retainer 33 of the first valve body unit 30.

[0046] A compression coil spring 55 is disposed between the attractor 52 and the plunger 53. The compression coil spring 55 applies a biasing force in the separating direction to the attractor 52 and the plunger 53. The coil 54 is disposed with the can 51 inserted therein.

[0047] (Operation of the flow path switching valve) Next, the operation of the flow path switching valve 1 will be described. In a state where the coil 54 of the drive device 50 is not energized, the plunger 53 and the drive shaft 57 are raised by the biasing force of the compression coil spring 55. For this reason, due to the biasing force of the coil spring 15, as shown in FIG. 1, the first valve body unit 30, the valve shaft 20, and the second valve body unit 40 are integrally raised.

[0048] When the first valve body unit 30 rises, the first valve body 34 separates from the first valve seat 11i. As a result, the fluid that has entered the valve chamber VC through the inlet flow path in the inlet tubular portion 11b passes through the gap between the first valve body 34 and the first valve seat 11i and is discharged through the first outlet flow path in the first outlet tubular portion 11c through the inside of the upper cylindrical portion 11e.

[0049] On the one hand, as the second valve body unit 40 rises, the second valve body 44 seats on the second valve seat 11k. Therefore, the fluid that has entered the valve chamber VC is not discharged through the second port flow path in the second outlet tubular portion 11d. Thus, the fluid flows from the inlet flow path to only the first outlet flow path through the flow path switching valve 1.

[0050] On the other hand, when the coil 54 of the drive device 50 is energized, the plunger 53 and the drive shaft 57 descend against the biasing force of the compression coil spring 55 due to the generated magnetic force. For this reason, against the biasing force of the coil spring 15, as shown in FIG. 2, the first valve body unit 30, the valve shaft 20, and the second valve body unit 40 descend integrally.

[0051] Due to the descent of the second valve body unit 40, the second valve body 44 separates from the second valve seat 11k. As a result, the fluid that has entered the valve chamber VC through the inlet flow path in the inlet tubular portion 11b passes through the gap between the second valve body 44 and the second valve seat 11k, passes through the inside of the lower cylindrical portion 11f, and is discharged through the second outlet flow path in the second outlet tubular portion 11d.

[0052] On the one hand, since the first valve body 34 of the first valve body unit 30 seats on the first valve seat 11i, the fluid that has entered the valve chamber VC is not discharged through the first port flow path in the first outlet tubular portion 11c. Thus, the fluid flows from the inlet flow path to only the second outlet flow path through the flow path switching valve 1.

[0053] (Comparison with the comparative example) Here, as in the configuration shown in Patent Document 1, for example, a comparative example is taken in which the first valve body unit 30 does not have a first communication opening, the second valve body unit 40 does not have a second communication opening, and the valve shaft 20 has an opening that communicates with the first pressure equalizing chamber EC1 and the second pressure equalizing chamber EC2. In this comparative example, for example, when the second valve body 44 seats on the second valve seat 11k, the first pressure equalizing chamber EC1 and the second pressure equalizing chamber EC2 have the same fluid pressure.

[0054] Also in the comparative example, when the second valve element 44 is seated on the second valve seat 11k, similarly to the present embodiment, the fluid flows from the inlet flow path only to the first outlet flow path through the flow path switching valve 1. For this reason, near the lower end of the first valve element unit 30, the fluid pressure becomes low due to the fluid flowing toward the first outlet flow path, while near the upper end of the second valve element unit 40 (inside the second valve port) in the valve chamber VC, the fluid flow stagnates and the fluid pressure becomes high.

[0055] As described above, in the comparative example, when the second valve element 44 is seated on the second valve seat 11k, the first pressure equalizing chamber EC1 and the second pressure equalizing chamber EC2 have the same fluid pressure. However, when the fluid pressure inside the second valve port becomes high due to the stagnation of the flow, the fluid pressure in the second pressure equalizing chamber EC2 becomes relatively low across the second valve element unit 40. As a result, the pressure balance is disrupted, which may affect the driving of the valve shaft 20 by the driving device 50. A similar problem may also occur when the first valve element 34 is seated on the first valve seat 11i.

[0056] On the other hand, according to the present embodiment, the first valve element unit 30 has the first communication opening, and the cross-sectional area of the first pressure equalizing chamber EC1 in the direction orthogonal to the axis is equal to the cross-sectional area of the first valve port in the direction orthogonal to the axis. Also, the second valve element unit 40 has the second communication opening, and the cross-sectional area of the second pressure equalizing chamber EC2 in the direction orthogonal to the axis is equal to the cross-sectional area of the second valve port in the direction orthogonal to the axis.

[0057] For this reason, even if the second valve element 44 is seated on the second valve seat 11k, the internal pressure of the second pressure equalizing chamber EC2 becomes equal to the internal pressure of the second valve port across the second valve element unit 40. Also, even if the first valve element 34 is seated on the first valve seat 11i, the internal pressure of the first pressure equalizing chamber EC1 becomes equal to the internal pressure of the first valve port across the first valve element unit 30. For this reason, regardless of the axial position of the valve shaft 20, by canceling the pressure difference across the second valve element unit 40, the driving device 50 can stably drive the valve shaft 20. Similarly, when the first valve element 34 is seated on the first valve seat 11i, the internal pressure of the first pressure equalizing chamber EC1 becomes equal to the internal pressure of the first valve port, so the pressure difference across the first valve element unit 30 can be canceled.

[0058] FIG. 4 is a diagram showing the experimental results obtained by the inventors. The vertical axis represents the axial load received by one valve body unit, and the horizontal axis represents the axial position (valve lift amount) of the valve shaft. The graph X of the present embodiment is compared with the graph Y of the above-described comparative example and shown. Here, it is assumed that when the valve lift amount is 0 mm, the first valve body 34 seats on the first valve seat 11i, and when the valve lift amount is 5 mm, the second valve body 44 seats on the second valve seat 11k. Also, the first valve body unit 30 and the second valve body unit 40 receive loads in opposite directions according to the valve lift amount.

[0059] As shown in FIG. 4, in the graph Y of the comparative example, the load received by the valve body unit varies greatly across the valve lift amount of 2.5 mm (intermediate position). In contrast, in the graph X of the present embodiment, the load received by the valve body unit is lower across the entire range of the valve lift amount compared to the graph Y of the comparative example, and the load fluctuation is also small. Specifically, in the states of the valve lift amounts of 5 mm and 0 mm, in the graph Y of the comparative example, the valve body unit receives the maximum load, whereas the load received by the valve body unit of the graph X of the present embodiment is reduced to 1 / 20 or less of the maximum load of the comparative example. Thus, it is clear that the effect of the present embodiment is effective. Also, since the maximum load received by the valve body unit is reduced, the force required to drive the valve shaft 20 is also less, enabling miniaturization and power saving of the drive device 50, and also improving the degree of freedom in its selection.

[0060] Furthermore, according to the present embodiment, the first communication opening of the first valve body unit 30 and the first valve seat 11i are separated from each other by a distance B in the axial direction, and a buffer chamber BF1 exists between them. Therefore, even when pressure fluctuations occur when the first valve body 34 separates from the first valve seat 11i and fluid passes through, the pressure fluctuations are averaged by the first buffer chamber BF1 and transmitted to the first pressure equalizing chamber EC1 through the first communication opening, so that the influence of the pressure fluctuations can be suppressed as much as possible. The second buffer chamber BF2 of the second valve body unit 40 also has a similar function. Note that the value of the distance B is preferably, for example, 1 / 3 or more and 2 / 3 or less of the axial length of the first valve body unit 30.

[0061] (Modification example) FIG. 3C is a cross-sectional view showing an enlarged periphery of the first valve body unit 30' according to a modified example, and shows a state of being seated on the first valve seat 11i. FIG. 3D is a cross-sectional view showing an enlarged periphery of the second valve body unit 40', and shows a state of being separated from the second valve seat 11k. For the components common to the above-described embodiment, the same reference numerals are given and redundant description is omitted.

[0062] In this modified example, the first communication opening and the second communication opening are provided in the valve shaft 20' without forming communication openings in the first valve body unit 30' and the second valve body unit 40'. Specifically, as shown in FIG. 3C, the first valve body unit 30' does not have a first communication opening, and the valve shaft 20' has a first vertical hole 25 extending along the axis L of the valve body 10 from the upper end, and a first horizontal hole 26 intersecting the first vertical hole 25 and opening in the first buffer chamber BF1. The first communication opening is constituted by the first vertical hole 25 and the first horizontal hole 26.

[0063] Further, as shown in FIG. 3D, the second valve body unit 40' does not have a second communication opening, and the valve shaft 20' has a second vertical hole 27 extending along the axis L of the valve body 10 from the lower end, and a second horizontal hole 28 intersecting the second vertical hole 27 and opening in the second buffer chamber BF2. The second communication opening is constituted by the second vertical hole 27 and the second horizontal hole 28. Note that a communication opening may be provided in one of the first valve body unit 30' and the second valve body unit 40', and a communication opening may be provided in the corresponding valve shaft 20' of the other.

[0064] (Second Embodiment) FIG. 5 is a longitudinal sectional view of the flow path switching valve 1A according to the second embodiment, showing a state in which the inlet flow path and the first outlet flow path are in communication, and FIG. 6 is a longitudinal sectional view of the flow path switching valve 1A according to the second embodiment, showing a state in which the inlet flow path and the second outlet flow path are in communication.

[0065] The flow path switching valve 1A of the present embodiment is different from the above-described embodiment in that the first closing member 12A and the second closing member 13A are different. Since the other configurations are the same as those of the above-described embodiment, the same reference numerals are given and redundant description is omitted.

[0066] FIG. 7(a) is a cross-sectional view showing an enlarged periphery of the first valve body unit 30 of the present embodiment, showing a state where the first valve body 34 is separated from the first valve seat 11i, and FIG. 7(b) is a cross-sectional view showing an enlarged periphery of the first valve body unit 30 of the present embodiment, showing a state where the first valve body 34 is seated on the first valve seat 11i.

[0067] The first closing member 12A has a tapered portion 12Ad that expands in diameter upwardly connected to a cylindrical portion 12Ae at the center on the inner periphery of the upper end side. As shown in FIG. 7(a), in a state where the first valve body 34 is separated from the first valve seat 11i, the sealing body 32a of the first seal portion 32 moves from the cylindrical portion 12Ae to the more-diameter tapered portion 12Ad. For this reason, since the sliding resistance of the first seal portion 32 with respect to the first closing member 12A is reduced, the driving force of the driving device 50 can be further reduced. Also, in a state where the first valve body 34 is separated from the first valve seat 11i, since the fluid pressure near the lower end of the first main body 31 becomes low, there is no particular need to consider fluid leakage from within the first pressure equalizing chamber EC.

[0068] On the other hand, as shown in FIG. 7(b), when the first valve body 34 is seated on the first valve seat 11i, the sealing body 32a of the first seal portion 32 moves from the tapered portion 12Ad to the smaller-diameter cylindrical portion 12Ae. For this reason, by increasing the adhesion force of the first seal portion 32 with respect to the first closing member 12A, fluid leakage from within the first pressure equalizing chamber EC can be suppressed, and the fluid pressure near the lower end of the first main body 31 and the internal pressure of the first pressure equalizing chamber EC can be made uniform through the first communication opening.

[0069] In other words, when the first valve body 34 is separated from the first valve seat 11i, the inner diameter of the position where the sealing body 32a of the first seal portion 32 abuts against the first closing member 12A is larger than the inner diameter of the position where the sealing body 32a of the first seal portion 32 abuts against the first closing member 12A when the first valve body 34 is seated on the first valve seat 11i.

[0070] Similarly, as shown in FIGS. 5 and 6, the second closing member 13 also has a tapered portion 13Ad that expands in diameter downward on the inner circumference of the lower end side and is connected to a cylindrical portion 13Ae at the center. Therefore, when the second valve body 44 is separated from the second valve seat 11k, the inner diameter of the position where the sealing body of the second seal portion 42 abuts against the second closing member 13 is larger than the inner diameter of the position where the sealing body of the second seal portion 42 abuts against the second closing member 13 when the second valve body 44 is seated on the second valve seat 11k. For this reason, the sliding resistance of the second seal portion 42 with respect to the second closing member 13A can be reduced.

[0071] The present invention is not limited to solenoid valves and is applicable to all flow path switching valves that drive a valve body by supplying power to an electromagnetic coil.

Explanation of Reference Numerals

[0072] 1, 1A Flow path switching valve 10 Valve body 11b Inlet tubular portion 11c First outlet tubular portion 11d Second outlet tubular portion 11i First valve seat 11k Second valve seat 12 First closing member 13 Second closing member 20, 20’ Valve shaft 25 First vertical hole 26 First horizontal hole 27 Second vertical hole 28 Second horizontal hole 30, 30’ First valve body unit 31 First body 31f First pressure equalizing hole 32 First seal portion 32e, 32f Communication hole 33 First seal retainer 33b Communication hole 34 First valve body 40, 40’ Second valve body unit 41 Second body 41f Second pressure equalizing hole 42 Second seal portion 43 Second seal retainer 44 Second valve body 50 Driving device BF1 First buffer chamber BF2 Second buffer chamber EC1 First pressure equalizing chamber EC2 Second pressure equalizing chamber VC Valve chamber

Claims

1. A valve body including a first flow path communicating with a valve chamber, a second flow path and a third flow path communicating with the valve chamber, a first valve seat formed between the valve chamber and the second flow path, and a second valve seat formed between the valve chamber and the third flow path; A valve shaft movably accommodated in the valve body in the axial direction of the valve body; A first valve body unit attached to the valve shaft and including a first valve body capable of contacting the first valve seat; A second valve body unit attached to the valve shaft and including a second valve body capable of contacting the second valve seat; A first pressure equalizing chamber is formed in the valve body on the side opposite to the valve chamber with the first valve body unit interposed therebetween, and a second pressure equalizing chamber is formed in the valve body on the side opposite to the valve chamber with the second valve body unit interposed therebetween; A first communication opening communicating the first pressure equalizing chamber and the valve chamber is formed in the first valve body unit; A second communication opening communicating the second pressure equalizing chamber and the valve chamber is formed in the second valve body unit; A hollow cylindrical first closing member attached to one end in the axial direction of the valve body and a hollow cylindrical second closing member attached to the other end in the axial direction of the valve body, wherein the first pressure equalizing chamber is formed inside the first closing member and the second pressure equalizing chamber is formed inside the second closing member; The first valve body unit has a first sealing portion that contacts and seals the inner periphery of the first closing member; The second valve body unit has a second sealing portion that contacts and seals the inner periphery of the second closing member; When the first valve body is separated from the first valve seat, the inner diameter of the position where the first sealing portion contacts the first closing member is larger than the inner diameter of the position where the first sealing portion contacts the first closing member when the first valve body is seated on the first valve seat; When the second valve body is separated from the second valve seat, the inner diameter of the position where the second sealing portion contacts the second closing member is larger than the inner diameter of the position where the second sealing portion contacts the second closing member when the second valve body is seated on the second valve seat; A flow path switching valve characterized by the above.

2. A valve body including a first flow path communicating with a valve chamber, a second flow path and a third flow path communicating with the valve chamber, a first valve seat formed between the valve chamber and the second flow path, and a second valve seat formed between the valve chamber and the third flow path; A valve shaft movably accommodated in the valve body in the axial direction of the valve body; A first valve body unit including a first valve body attached to the valve shaft and capable of contacting the first valve seat; A second valve body unit including a second valve body attached to the valve shaft and capable of contacting the second valve seat, and having; In the valve body, a first pressure equalizing chamber is formed on the side opposite to the valve chamber with the first valve body unit interposed therebetween, and a second pressure equalizing chamber is formed on the side opposite to the valve chamber with the second valve body unit interposed therebetween; In the first valve body unit, a first communication opening for communicating the first pressure equalizing chamber and the valve chamber is formed; In the second valve body unit, a second communication opening for communicating the second pressure equalizing chamber and the valve chamber is formed; A hollow cylindrical first closing member attached to one end of the valve body in the axial direction, and a hollow cylindrical second closing member attached to the other end of the valve body in the axial direction, wherein the first pressure equalizing chamber is formed inside the first closing member, and the second pressure equalizing chamber is formed inside the second closing member; The first valve body unit has a first sealing portion that contacts and seals the inner circumference of the first closing member; The second valve body unit has a second sealing portion that contacts and seals the inner circumference of the second closing member; The first sealing portion has a communication hole corresponding to the first communication opening, and the second sealing portion has a communication hole corresponding to the second communication opening; A flow path switching valve characterized by the above.

3. Having a driving portion for driving the valve shaft in the axial direction; The flow path switching valve according to claim 1 or 2, characterized by the above.

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