JP7710239B2 - Flow path switching valve - Google Patents

Description

The present invention relates to a flow path switching valve.

As an example of a flow path switching valve, Patent Document 1 discloses a flow path switching valve that can reduce the load acting on the valve body when switching the flow path, thereby reducing the drive torque of the valve body, thereby enabling miniaturization, large capacity, power saving, etc.

JP 2017-129240 A

According to the flow path switching valve of Patent Document 1, a through hole that passes through the connecting shaft in the axial direction forms a pressure equalization passage that connects the back pressure chamber defined above the upper valve body with the lower space formed below the lower valve body. This pressure equalization passage makes it possible to equalize the internal pressure of the back pressure chamber and the internal pressure of the lower space, thereby making it possible to balance 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.

However, in the configuration of Patent Document 1, when the valve opening is large, the valve body drive becomes unstable. In response to this, the inventors conducted extensive research and discovered that a pressure difference occurs between the vicinity of the upper valve body and the vicinity of the lower valve body in the valve chamber due to the flow of fluid from the inlet of the flow path switching valve toward the first outlet or the second outlet, and that this pressure difference changes the axial force applied to the upper valve body and the lower valve body, causing the balance of the axial forces applied to the upper valve body and the lower valve body to be lost.

The present invention was made in consideration of the above problems, and aims to provide a flow path switching valve that can ensure stable valve body operation regardless of the valve opening degree.

The flow path switching valve of the present invention comprises:
a valve body including: a first flow passage communicating with a valve chest, a second flow passage and a third flow passage communicating with the valve chest, a first valve seat formed between the valve chest and the second flow passage, and a second valve seat formed between the valve chest and the third flow passage;
a valve stem accommodated within the valve body so as to be movable in an axial direction of the valve body;
a first valve body unit including a first valve body attached to the valve shaft and 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 opposite side to the valve chest across the first valve body unit, and a second pressure equalizing chamber is formed on the opposite side to the valve chest across the second valve body unit,
The first valve body unit is formed with a first communication opening that communicates between the first pressure equalizing chamber and the valve chamber,
a second communication opening that communicates between 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 axial end of the valve body, and a hollow cylindrical second closing member attached to the other axial end of the valve body, the first pressure equalizing chamber being formed inside the first closing member, and the second pressure equalizing chamber being formed inside the second closing member,
The first valve body unit has a first seal portion that abuts against an inner periphery of the first closing member to form a seal,
the second valve body unit has a second seal portion that abuts against an inner periphery of the second closing member to form a seal;
an inner diameter at a position where the first seal portion abuts against the first closing member when the first valve body is separated from the first valve seat is larger than an inner diameter at a position where the first seal portion abuts against the first closing member when the first valve body is seated on the first valve seat,
The present invention is characterized in that when the second valve body is separated from the second valve seat, the inner diameter at a position where the second seal portion abuts against the second closing member is larger than the inner diameter at a position where the second seal portion abuts against the second closing member when the second valve body is seated on the second valve seat .
The flow path switching valve of the present invention comprises:
a valve body including: a first flow passage communicating with a valve chest, a second flow passage and a third flow passage communicating with the valve chest, a first valve seat formed between the valve chest and the second flow passage, and a second valve seat formed between the valve chest and the third flow passage;
a valve stem accommodated within the valve body so as to be movable in an axial direction of the valve body;
a first valve body unit including a first valve body attached to the valve shaft and 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 opposite side to the valve chest across the first valve body unit, and a second pressure equalizing chamber is formed on the opposite side to the valve chest across the second valve body unit,
The first valve body unit is formed with a first communication opening that communicates between the first pressure equalizing chamber and the valve chamber,
a second communication opening that communicates between 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 axial end of the valve body, and a hollow cylindrical second closing member attached to the other axial end of the valve body, the first pressure equalizing chamber being formed inside the first closing member, and the second pressure equalizing chamber being formed inside the second closing member,
The first valve body unit has a first seal portion that abuts against an inner periphery of the first closing member to form a seal,
the second valve body unit has a second seal portion that abuts against an inner periphery of the second closing member to form a 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.

The present invention provides a flow path switching valve that ensures stable valve body operation regardless of the valve opening degree.

FIG. 1 is a vertical cross-sectional view of a flow path switching valve according to a first embodiment. FIG. 2 is a vertical cross-sectional view of the flow path switching valve according to the first embodiment. FIG. 3A is an enlarged cross-sectional view showing the periphery of the first valve body unit. FIG. 3B is an enlarged cross-sectional view showing the periphery of the second valve body unit. FIG. 3C is an enlarged cross-sectional view showing the periphery of a first valve body unit according to a modified example. FIG. 3D is an enlarged cross-sectional view showing the periphery of a second valve body unit according to a modified example. FIG. 4 is a diagram showing the results of an experiment conducted by the present inventors. FIG. 5 is a vertical sectional view of a flow path switching valve according to the second embodiment. FIG. 6 is a vertical sectional view of a flow path switching valve according to the second embodiment. FIG. 7 is an enlarged cross-sectional view showing the periphery of the first valve body unit.

The flow path switching valve according to an embodiment of the present invention will be described below with reference to the drawings. In this specification, the drive device side is referred to as the upper side, and the opposite side is referred to as the lower side.

(First embodiment)
Fig. 1 is a longitudinal sectional view of the 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) are in communication with each other, 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 an inlet flow path and a second outlet flow path (third flow path) are in communication with each other. The axis of the flow path switching valve 1 is designated as L. In this embodiment, the fluid flowing in from the first flow path is switched by the flow path switching valve 1 to be discharged from the second flow path or the third flow path, but in the opposite 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.

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

The valve body 10 has a valve housing 11, a first closing member 12, a second closing member 13, and a cover member 14.

The valve housing 11 is made up of 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.

The main body 11a is made up of an upper cylindrical portion 11e with an open top end, a lower cylindrical portion 11f with an open bottom end, and an intermediate cylindrical portion 11g that has a smaller diameter than the upper cylindrical portion 11e and the lower cylindrical portion 11f and connects them coaxially.

At the joint between the intermediate cylindrical portion 11g and the upper cylindrical portion 11e, the inner edge of the intermediate cylindrical portion 11g protrudes toward the upper cylindrical portion 11e to form the upper short circular pipe portion 11h. The tip of the upper short circular pipe portion 11h forms the first valve seat 11i. The interior of the intermediate cylindrical portion 11g forms the valve chamber VC. The first valve seat 11i is formed between the valve chamber VC and the first outlet flow path.

At the joint between the intermediate cylindrical section 11g and the lower cylindrical section 11f, the inner edge of the intermediate cylindrical section 11g protrudes toward the lower cylindrical section 11f to form the lower short circular pipe section 11j. The tip of the lower short circular pipe section 11j forms the second valve seat 11k. The second valve seat 11k is formed between the valve chamber VC and the second outlet flow path.

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

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

The second outlet tubular portion 11d extends from the lower cylindrical portion 11f in a direction perpendicular to the axis L of the valve body 10 on the opposite side of the axis L of the valve body 10 from the inlet tubular portion 11b, and a second outlet flow passage 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.

The solid cylindrical valve shaft 20 is made up of an upper shaft 21, an intermediate shaft 22, and a lower shaft 23, all connected coaxially. The valve shaft 20 has a first valve body unit 30 and a second valve body unit 40 attached to both ends, which are integrally movable in the axial direction.

The hollow cylindrical first closing member 12 is made up of an expanded diameter section 12a, an intermediate section 12b having a smaller diameter than the expanded diameter section 12a, and an annular section 12c protruding downward from the lower end of the intermediate section 12b. In this embodiment, the inner diameters (cylindrical inner circumference) of the expanded diameter section 12a, the intermediate section 12b, and the upper half of the annular section 12c, which are constantly in contact with the sealing body 32a of the first sealing section 32 described below, are equal.

On the other hand, the inner diameter of the lower half of the annular portion 12c is tapered so that the diameter increases toward the bottom. The first closure member 12 is inserted from above into the upper cylindrical portion 11e of the valve housing 11, and is attached to the upper end of the valve housing 11 by fitting the stepped portion between the expanded diameter portion 12a and the middle portion 12b against the stepped portion at the upper end opening of the upper cylindrical portion 11e of the valve housing 11.

Figure 3A is an enlarged cross-sectional view of the first valve body unit 30 and its periphery, showing it seated on the first valve seat 11i. The first valve body unit 30 has a cylindrical first main body 31, a first seal portion 32, a first seal retainer 33, a first valve body 34, and a first spacer 35.

The first body 31 has a small diameter portion 31a that fits around the inner circumference of the first closing member 12 and is axially slidable, a large diameter portion 31b that is larger in 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 crimped portion 31c that is connected to the lower end of the large diameter portion 31b.

The annular first valve body 34, together with the smaller-diameter annular first spacer 35, is inserted from below into the crimped portion 31c, which is cylindrical before being crimped. The lower end of the crimped portion 31c is then crimped and plastically deformed to expand its diameter, thereby fixing the first valve body 34 to the first body 31 via the first spacer 35. At this time, the radial outer side of the first valve body 34 is exposed from the first spacer 35, and its lower surface faces the first valve seat 11i of the valve housing 11.

The small diameter portion 31a and the large diameter portion 31b have a large diameter opening 31d with an inner diameter equal to the minimum inner diameter of the crimped portion 31c, and a small diameter opening 31e that communicates with the large diameter opening 31d, which are coaxial with each other. In addition, a first pressure equalizing hole 31f is formed in parallel with the small diameter opening 31e, extending from the upper end of the large diameter opening 31d toward the upper end of the first body 31.

The first seal part 32 installed at the upper end of the first body 31 has a flexible resin seal body 32a and a metal leaf spring 32b. The seal body 32a and the leaf spring 32b have central holes 32c and 32d corresponding to the small diameter opening 31e, and communication holes 32e and 32f corresponding to the first pressure equalizing hole 31f.

The first annular seal holder 33, which has a smaller diameter than the first 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.

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

The intermediate shaft 22 of the valve shaft 20 is inserted into the large diameter opening 31d of the first body 31, and its upper end abuts against the step between the small diameter opening 31e and the large diameter opening 31d. The upper shaft 21 also protrudes above the first valve body unit 30, penetrating the small diameter opening 31e, the central holes 32c and 32d of the seal body 32a and the leaf spring 32b, and the central hole 33a of the first seal retainer 33. The space between the large diameter opening 31d and the intermediate shaft 22 is the first buffer chamber BF1.

A thin-walled cylindrical crimped portion 21a is formed at the protruding upper end of the upper shaft 21, and the first seal portion 32 is fixed to the first body 31 via the first seal retainer 33 by crimping the upper end of the crimped portion 21a and plastically deforming it so as to expand its diameter. The lower half of the annular portion 12c is tapered to make it relatively easier to insert the first seal portion 32 when assembling it to the first closing member 12.

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 contacts the inner circumference of the first closing member 12 over the entire circumference, suppressing fluid leakage. In addition, the radially outer end of the leaf spring 32b bent upward contacts 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 this embodiment, the inner diameter of the first closing member 12 is equal within the range where the seal body 32a of the first seal part 32 that moves with the first valve body unit 30 can contact. Note that, as the first seal part 32, for example, one disclosed in JP 2017-223293 A can be used, and detailed description thereof will be omitted.

The space within the first closing member 12 sealed by the first seal portion 32 is referred to as the first pressure equalizing chamber EC1. The upper part of the first pressure equalizing chamber EC1, which is formed on the opposite side of the first valve body unit 30 from the valve chamber VC, is shielded by the drive device 50 described below. The first pressure equalizing chamber EC1 communicates with the valve chamber VC via the first pressure equalizing hole 31f, communication holes 32e, 32f, and communication hole 33b. The first pressure equalizing hole 31f, communication holes 32e, 32f, and communication hole 33b are referred to as the first communication opening.

Here, the inner diameter of the first closing member 12 is A, and the inner diameter of the first valve port, which is the inner circumference of the upper short circular tube portion 11h, is 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 of the first pressure equalizing chamber EC1 in the direction perpendicular to the axis is equal to the cross-sectional area of the first valve port in the direction perpendicular to the axis. In addition, when the first valve body 34 is seated on the first valve seat 11i, the axial distance from the first valve seat 11i to the upper end of the large diameter opening 31d is B. In other words, the first communication opening and the first valve seat 11i are separated by a distance B across the first buffer chamber BF1.

In FIG. 1, the hollow cylindrical second closing member 13 is inserted from below into the lower cylindrical portion 11f of the valve housing 11, and its upper end is attached to the lower end of the valve housing 11 with the upper end abutting against an inner peripheral step 11m formed at the middle position of the lower cylindrical portion 11f. The second closing member 13 has an annular groove 13a coaxially on its lower surface, and when 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.

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-walled cylindrical portion 14c formed coaxially on the upper surface of the annular plate portion 14a.

Figure 3B is an enlarged cross-sectional view of the periphery of the second valve body unit 40, showing it 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 spacer 45, and has a configuration similar to that of the first valve body unit 30, except that it is in an upside-down relationship, so a duplicated description will be omitted.

The second valve body unit 40 differs from the first valve body unit 30 in that a crimped cylindrical portion 41g is connected to the center of the lower end of the second body 41. After the second seal portion 42 and the second seal presser 43 are attached to the second body 41 so that the crimped cylindrical portion 41g penetrates, the lower end of the crimped cylindrical portion 41g is crimped and plastically deformed to expand the diameter, so that the second seal portion 42 is fixed to the second body 41 via the second seal presser 43. The lower shaft 23 of the valve shaft 20 is inserted into the second valve body unit 40. The space between the large diameter opening 41d of the second body 41 and the intermediate shaft 22 is the second buffer chamber BF2.

When assembled, the second seal portion 42 seals against the inner circumference of the second closing member 13. The inner diameter of the second closing member 13 is equal within the range where the seal body of the second seal portion 42, which moves with the second valve body unit 40, can abut. The second body 41 fits axially slidably against the inner circumference of the second closing member 13. The cover member 14 is attached to the lower end of the second closing member 13 while the thin-walled cylindrical portion 14c is fitted into the annular groove 13a. At this time, the coil spring 15 is disposed between the cover member 14 and the second seal retainer 43 of the second valve body unit 40, and biases the second valve body unit 40 upward against the cover member 14.

The space surrounded by the second valve body unit 40, the hollow cylindrical second closing member 13, and the cover member 14 is called the second pressure equalizing chamber EC2. The second pressure equalizing chamber EC2, which is formed on the opposite side of the second valve body unit 40 from the valve chamber VC, is connected to the valve chamber VC via 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.

The radial outer side of the second valve body 44 of the second valve body unit 40 is exposed from the second spacer 45, and its upper surface faces 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. In other words, the cross-sectional area of the second pressure equalizing chamber EC2 in the direction perpendicular to the axis is equal to the cross-sectional area of the second valve port in the direction perpendicular to the axis. The inner diameter is equal throughout the entire second closing member 13, including the range with which the seal portion of the second seal portion 42 is constantly in contact.

The drive device (drive unit) 50 is an electromagnetic actuator, and is disposed above the valve body 10, closing 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 attractor 52, a plunger 53, a coil 54, a compression coil spring 55, and a resin case 56 that houses these. The drive device 50 may also be one that drives the valve shaft 20 in the axial direction L using an electric motor or a solenoid.

The lower end of the can 51, which is formed into a cylindrical shape with a top, is attached near the upper end of the suction element 52. The suction element 52, which has a lower opening 52a, is attached to the upper end of the first closing member 12.

The plunger 53, which is slidably arranged within the can 51, has an upper opening 53a. The drive shaft 57, whose upper end is fitted and fixed in the upper opening 53a, is arranged to pass through the lower opening 52a and is configured to move integrally with the plunger 53. The lower end of the drive shaft 57 has an expanded diameter and protrudes downward from the suction element 52 so that it can abut against the upper surface of the first seal retainer 33 of the first valve body unit 30.

A compression coil spring 55 is disposed between the attractor 52 and the plunger 53. The compression coil spring 55 exerts a biasing force on the attractor 52 and the plunger 53 in the direction separating them. The coil 54 is disposed with the can 51 inserted inside.

(Operation of flow path switching valve)
Next, the operation of the flow path switching valve 1 will be described.
When the coil 54 of the drive unit 50 is not energized, the plunger 53 and the drive shaft 57 are raised by the biasing force of the compression coil spring 55. Therefore, the first valve body unit 30, the valve shaft 20, and the second valve body unit 40 are raised together by the biasing force of the coil spring 15, as shown in FIG.

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

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

In response to this, when electricity is applied to the coil 54 of the drive unit 50, the generated magnetic force causes the plunger 53 and drive shaft 57 to descend against the biasing force of the compression coil spring 55. As a result, as shown in FIG. 2, the first valve body unit 30, the valve shaft 20, and the second valve body unit 40 descend together against the biasing force of the coil spring 15.

As the second valve body unit 40 descends, the second valve body 44 moves away from the second valve seat 11k. As a result, the fluid that 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.

On the other hand, because the first valve body 34 of the first valve body unit 30 is seated on the first valve seat 11i, the fluid that has entered the valve chamber VC is not discharged through the first outlet flow path in the first outlet tubular portion 11c. Therefore, the fluid flows only from the inlet flow path to the second outlet flow path through the flow path switching valve 1.

(Comparison with Comparative Example)
Here, a comparative example will be taken as an example 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 openings that communicate with the first and second pressure equalizing chambers EC1 and EC2, as in the configuration shown in Patent Document 1. In this comparative example, for example, when the second valve body 44 is seated on the second valve seat 11k, the first and second pressure equalizing chambers EC1 and EC2 have equal fluid pressures.

In the comparative example, as in the present embodiment, when the second valve body 44 is seated on the second valve seat 11k, the fluid flows only from the inlet flow path to the first outlet flow path via the flow path switching valve 1. Therefore, near the lower end of the first valve body unit 30, the fluid pressure is low due to the fluid flowing toward the first outlet flow path, while near the upper end of the second valve body unit 40 in the valve chamber VC (inside the second valve port), the fluid flow is stagnated, and the fluid pressure is high.

As described above, in the comparative example, when the second valve body 44 is seated on the second valve seat 11k, the first pressure equalizing chamber EC1 and the second pressure equalizing chamber EC2 have equal fluid pressures. However, if the fluid pressure in the second valve port increases due to flow stagnation, the fluid pressure in the second pressure equalizing chamber EC2 becomes relatively low across the second valve body unit 40. This causes the pressure balance to be lost, which may affect the drive of the valve shaft 20 by the drive unit 50. A similar problem may occur when the first valve body 34 is seated on the first valve seat 11i.

In contrast, according to this embodiment, the first valve body unit 30 has a first communication opening, and the cross-sectional area of the first pressure equalizing chamber EC1 in the direction perpendicular to the axis is equal to the cross-sectional area of the first valve port in the direction perpendicular to the axis, and the second valve body unit 40 has a second communication opening, and the cross-sectional area of the second pressure equalizing chamber EC2 in the direction perpendicular to the axis is equal to the cross-sectional area of the second valve port in the direction perpendicular to the axis.

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

Figure 4 shows the results of an experiment conducted by the inventors, with the vertical axis representing the axial load received by one of the valve body units and the horizontal axis representing the axial position of the valve stem (valve lift amount), and shows a comparison between graph X of this embodiment and graph Y of the comparative example described above. Here, 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. In addition, the first valve body unit 30 and the second valve body unit 40 receive loads in opposite directions depending on the valve lift amount.

As shown in FIG. 4, in graph Y of the comparative example, the load received by the valve body unit fluctuates greatly around the valve lift amount of 2.5 mm (middle position). In contrast, in graph X of the present embodiment, the load received by the valve body unit is lower across the entire range of valve lift amounts compared to graph Y of the comparative example, and the load fluctuation is also small. Specifically, in the state of valve lift amounts of 5 mm and 0 mm, the valve body unit receives the maximum load in graph Y of the comparative example, whereas the load received by the valve body unit in graph X of the present embodiment is reduced to 1/20 or less of the maximum load in the comparative example, so that the effect of the present embodiment is clearly effective. In addition, since the maximum load received by the valve body unit is also reduced, less force is required to drive the valve shaft 20, which allows the drive device 50 to be made smaller and more energy-efficient, and improves the freedom of selection.

Furthermore, according to this embodiment, the first communication opening of the first valve body unit 30 and the first valve seat 11i are separated by a distance B in the axial direction, and a buffer chamber BF1 exists between them. Therefore, even if 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 via the first communication opening, so that the effects of the pressure fluctuations can be minimized. The second buffer chamber BF2 of the second valve body unit 40 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.

(Modification)
Fig. 3C is an enlarged cross-sectional view of the first valve body unit 30' according to the modified example, seated on the first valve seat 11i. Fig. 3D is an enlarged cross-sectional view of the second valve body unit 40', spaced apart from the second valve seat 11k. The same reference numerals are used to designate components common to the above-described embodiment, and redundant description will be omitted.

In this modified example, the first and second communication openings 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 that extends from the upper end along the axis L of the valve body 10, and a first horizontal hole 26 that intersects with the first vertical hole 25 and opens into the first buffer chamber BF1. The first vertical hole 25 and the first horizontal hole 26 form the first communication opening.

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 that extends from the lower end along the axis L of the valve body 10, and a second horizontal hole 28 that intersects with the second vertical hole 27 and opens into the second buffer chamber BF2. The second vertical hole 27 and the second horizontal hole 28 form a second communication opening. 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 valve shaft 20' corresponding to the other.

Second Embodiment
FIG. 5 is a longitudinal cross-sectional view of a flow path switching valve 1A according to a second embodiment, showing a state in which the inlet flow path and the first outlet flow path are connected, and FIG. 6 is a longitudinal cross-sectional view of a 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 connected.

The flow path switching valve 1A of this embodiment differs from the above-described embodiment in the first closing member 12A and the second closing member 13A. The rest of the configuration is the same as the above-described embodiment, so the same reference numerals are used and repeated explanations are omitted.

Figure 7(a) is an enlarged cross-sectional view of the periphery of the first valve body unit 30 of this embodiment, with the first valve body 34 spaced apart from the first valve seat 11i, and Figure 7(b) is an enlarged cross-sectional view of the periphery of the first valve body unit 30 of this embodiment, with the first valve body 34 seated on the first valve seat 11i.

The first closing member 12A has a tapered portion 12Ad on the inner circumference of the upper end side, which increases in diameter as it goes upward, connected to the cylindrical portion 12Ae in the center. As shown in FIG. 7(a), when the first valve body 34 is separated from the first valve seat 11i, the seal body 32a of the first seal portion 32 moves from the cylindrical portion 12Ae to the tapered portion 12Ad, which has a larger diameter. This reduces the sliding resistance of the first seal portion 32 against the first closing member 12A, thereby further reducing the driving force of the drive unit 50. In addition, when the first valve body 34 is separated from the first valve seat 11i, the fluid pressure near the lower end of the first body 31 is low, so there is no need to take fluid leakage from the first pressure equalizing chamber EC into consideration.

In response to this, as shown in FIG. 7(b), when the first valve body 34 is seated on the first valve seat 11i, the seal body 32a of the first seal portion 32 moves from the tapered portion 12Ad to the cylindrical portion 12Ae, which has a smaller diameter. This increases the adhesion of the first seal portion 32 to the first closing member 12A, thereby suppressing fluid leakage from within the first pressure equalizing chamber EC and equalizing the fluid pressure near the lower end of the first body 31 and the internal pressure of the first pressure equalizing chamber EC via the first communication opening.

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 seal 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 seal 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.

Similarly, as shown in Figures 5 and 6, the second closing member 13 also has a tapered section 13Ad on the inner circumference of the lower end side, which increases in diameter as it goes downward, connected to the central cylindrical section 13Ae. Therefore, when the second valve body 44 is separated from the second valve seat 11k, the inner diameter at the position where the seal body of the second seal part 42 abuts against the second closing member 13 is larger than the inner diameter at the position where the seal body of the second seal part 42 abuts against the second closing member 13 when the second valve body 44 is seated on the second valve seat 11k. Therefore, the sliding resistance of the second seal part 42 against the second closing member 13A can be reduced.

The present invention is not limited to solenoid valves, but can be applied to all flow path switching valves that drive a valve body by supplying power to an electromagnetic coil.

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 holder 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 holder 44 Second valve body 50 Drive device BF1 First buffer chamber BF2 Second buffer chamber EC1 First pressure equalizing chamber EC2 Second pressure equalizing chamber VC Valve chamber

Claims (3)

a valve body including: a first flow passage communicating with a valve chest, a second flow passage and a third flow passage communicating with the valve chest, a first valve seat formed between the valve chest and the second flow passage, and a second valve seat formed between the valve chest and the third flow passage;
a valve stem accommodated within the valve body so as to be movable in an axial direction of the valve body;
a first valve body unit including a first valve body attached to the valve shaft and 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 opposite side to the valve chest across the first valve body unit, and a second pressure equalizing chamber is formed on the opposite side to the valve chest across the second valve body unit,
The first valve body unit is formed with a first communication opening that communicates between the first pressure equalizing chamber and the valve chamber,
a second communication opening that communicates between 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 axial end of the valve body, and a hollow cylindrical second closing member attached to the other axial end of the valve body, the first pressure equalizing chamber being formed inside the first closing member, and the second pressure equalizing chamber being formed inside the second closing member,
The first valve body unit has a first seal portion that abuts against an inner periphery of the first closing member to form a seal,
the second valve body unit has a second seal portion that abuts against an inner periphery of the second closing member to form a seal;
an inner diameter at a position where the first seal portion abuts against the first closing member when the first valve body is separated from the first valve seat is larger than an inner diameter at a position where the first seal portion abuts against the first closing member when the first valve body is seated on the first valve seat,
an inner diameter at a position where the second seal portion abuts against the second closing member when the second valve body is separated from the second valve seat is larger than an inner diameter at a position where the second seal portion abuts against the second closing member when the second valve body is seated on the second valve seat;
A flow path switching valve. a valve body including: a first flow passage communicating with a valve chest, a second flow passage and a third flow passage communicating with the valve chest, a first valve seat formed between the valve chest and the second flow passage, and a second valve seat formed between the valve chest and the third flow passage;
a valve stem accommodated within the valve body so as to be movable in an axial direction of the valve body;
a first valve body unit including a first valve body attached to the valve shaft and 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 opposite side to the valve chest across the first valve body unit, and a second pressure equalizing chamber is formed on the opposite side to the valve chest across the second valve body unit,
The first valve body unit is formed with a first communication opening that communicates between the first pressure equalizing chamber and the valve chamber,
a second communication opening that communicates between 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 axial end of the valve body, and a hollow cylindrical second closing member attached to the other axial end of the valve body, the first pressure equalizing chamber being formed inside the first closing member, and the second pressure equalizing chamber being formed inside the second closing member,
The first valve body unit has a first seal portion that abuts against an inner periphery of the first closing member to form a seal,
the second valve body unit has a second seal portion that abuts against an inner periphery of the second closing member to form a 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.
A flow path switching valve . A drive unit that drives the valve shaft in an axial direction.
3. The flow path switching valve according to claim 1 or 2 .