阅读说明：本技术 滑阀式切换阀 (Slide valve type switching valve ) 是由 宫添真司 野口和宏 于 2020-02-17 设计创作，主要内容包括：一种滑阀式切换阀,其在凸台部具备安装填料的凹槽,由该凹槽的构造的改进尽可能地抑制压缩流体流入凹槽的槽底面和填料的内周面之间。滑阀式切换阀(1)在滑阀(20)的凸台部(22)具备安装填料(13)的凹槽(50),其中,以槽底面的轴L方向长度的一半或者比其大的轴方向长度由从上游侧端(54)侧朝向下游侧端(55)侧连续性地缩径的倾斜面(52)形成凹槽的槽底面(51),使填料的内周面(14)在规定倾斜面的上游侧端侧的端部(52a)的压接点(S)相对于槽底面与应力集中相伴地压接,在将上述倾斜面与上述轴构成的角度作为α时,使槽底面中的连结上述压接点和上述上游侧端之间的连结面(53)与上述轴构成的角度θ为0°≦θ≦α的范围。(A spool valve type switching valve is provided with a recessed groove for receiving a packing in a boss portion, and the inflow of a compressed fluid between the groove bottom surface of the recessed groove and the inner peripheral surface of the packing is suppressed as much as possible by improving the structure of the recessed groove. A spool valve type switching valve (1) is provided with a recessed groove (50) for attaching a packing (13) in a boss portion (22) of a spool (20), wherein a groove bottom surface (51) of the recessed groove is formed by an inclined surface (52) continuously reducing the diameter from an upstream side end (54) side to a downstream side end (55) side by half or more of the axial length of the groove bottom surface, a pressure contact point (S) of an inner peripheral surface (14) of the packing at an end (52a) on the upstream side end side of a predetermined inclined surface is brought into pressure contact with the groove bottom surface together with stress concentration, and when the angle formed by the inclined surface and the shaft is defined as alpha, the angle theta formed by a connecting surface (53) in the groove bottom surface and the shaft, the connecting point and the upstream side end, is in the range of 0 DEG ≦ theta ≦ α.)

1. A slide valve type switching valve is characterized in that,

the switching valve includes a spool hole, a spool, and a valve driving unit, the spool hole connecting at least a pair of flow paths for flowing the compressed fluid and extending in an axial direction; the slide valve is inserted into the slide valve hole movably in the axial direction; the valve driving part makes the slide valve move in the axial direction to switch the communication state between the flow paths,

in the spool valve, a boss portion as a valve portion having an annular sliding portion on an outer periphery around an axis and a small diameter portion having an outer diameter smaller than the boss portion are formed adjacent to each other in an axial direction,

an annular groove opened in the radial direction is provided around the sliding portion of the boss portion, an annular packing made of an elastic material is accommodated in the groove,

an annular valve seat portion and an annular large diameter portion are formed on an inner surface of the spool hole so as to be adjacent to each other in an axial direction, the annular valve seat portion being a valve seat portion in which the boss portion is slidably fitted in the axial direction with the sliding portion thereof facing each other, the annular large diameter portion having an inner diameter larger than that of the valve seat portion, and the pair of flow passages being connected to both sides in the axial direction with the valve seat portion interposed therebetween,

the communication state between the pair of flow paths can be switched to a state in which: a state in which the boss portion is disposed in the large diameter portion and the small diameter portion is disposed in the valve seat portion, and the pair of flow paths communicate with each other; and a state in which the boss portion is disposed in the valve seat portion and the communication between the pair of flow paths is blocked,

the annular groove has a groove bottom surface having an upstream side end, which is disposed on a flow path side where the compressed fluid flows in the pair of flow paths in the axial direction when the pair of flow paths communicate with each other, and a downstream side end, which is disposed on a flow path side where the compressed fluid flows out from the spool hole, and a pair of side wall surfaces, which are provided upright from the upstream side end and the downstream side end of the groove bottom surface and face each other,

the groove bottom surface of the recessed groove has an inclined surface whose axial length is half or more than the axial length of the groove bottom surface, the inclined surface continuously decreases in diameter from the upstream side end side toward the downstream side end side, the inner peripheral surface of the filler is pressed against the groove bottom surface at a pressure contact point defining an end portion of the inclined surface on the upstream side end side, the pressure contact point being associated with stress concentration,

when an angle formed by the inclined surface and the shaft is defined as α, an angle θ formed by a connecting surface between the pressure contact point and the upstream end in the bottom surface of the connecting groove and the shaft is in a range of 0 ° ≦ θ ≦ α.

2. A spool valve type switching valve according to claim 1,

in the cross section of the groove, the inclined surface and the connecting surface of the groove bottom surface are respectively formed in a straight line shape.

3. A spool valve type switching valve according to claim 1,

the angle alpha formed by the inclined surface and the shaft is in the range of 10 DEG ≦ alpha.

4. A spool valve type switching valve according to claim 1,

the inner peripheral surface of the packing is in pressure contact with the pressure contact point of the groove bottom surface at a portion closer to the upstream side end than the center thereof.

5. A spool valve type switching valve according to claim 1,

the filler has a pair of side surfaces connected to both ends of the inner peripheral surface in the width direction and facing away from each other,

in the concave groove, a downstream side surface of the pair of side surfaces of the packing, which is disposed on the downstream side end side, is always in contact with a downstream side wall surface of the pair of side wall surfaces of the concave groove, which is provided upright from a downstream side end of the groove bottom surface.

6. A spool valve type switching valve according to claim 1,

in a cross section of the packing in a state of not being mounted in the groove, an inner peripheral surface of the packing is formed in a straight line shape parallel to the shaft.

7. A spool valve type switching valve according to claim 6,

the cross section of the filler in a state of not being mounted in the groove is formed to be bilaterally symmetrical with respect to a center line extending in a radial direction through the center of the inner peripheral surface thereof.

8. A spool valve type switching valve according to claim 7,

in a cross section of the filler in a state of not being fitted in the recess, a pair of side surfaces of the filler are respectively formed in a straight line shape gradually approaching the center line from the inner circumferential side to the outer circumferential side.

9. A spool valve type switching valve according to claim 1,

a pair of side wall surfaces of the groove extend in a direction orthogonal to the axis.

10. A spool valve type switching valve according to claim 1,

the packing is formed to have an outer diameter equal to or larger than an inner diameter of a seat portion of the spool hole in a state where the packing is fitted in the recessed groove.

11. A spool valve type switching valve according to claim 1,

the flow paths connected to the spool are an air supply flow path, an output flow path, and an exhaust flow path, the output flow path is connected between the air supply flow path and the exhaust flow path in the axial direction,

the pair of the flow paths are an output flow path and an exhaust flow path,

the output flow path is an upstream flow path through which the compressed fluid flows into the spool hole, and the exhaust flow path is a downstream flow path through which the compressed fluid flows out of the spool hole.

Technical Field

The present invention relates to a spool valve type switching valve in which a spool is slidably accommodated in a spool hole.

Background

The following spool-type switching valves have been widely known: having a gas supply port for connection to a source of fluid pressure; an output port for outputting the compressed fluid from the fluid pressure source to an external device such as various motion actuators; and exhaust ports for discharging exhaust gas returned from various operation actuators, and a spool valve serving as a valve body is operated in a spool hole connecting the ports to switch a communication state between the ports.

In such a spool valve type switching valve, the spool is formed by disposing annular recessed portions, which form communication passages between the boss portions as the valve portions and the ports, alternately in adjacent relation in the axial direction. Further, the inner surface of the spool hole is formed by alternately disposing, adjacent to each other in the axial direction, an annular valve seat portion (valve seat surface) which slidably fits the boss portion by the operation of the spool to block communication between the adjacent ports, and an annular groove which forms a communication passage between the ports together with the annular recess portion by placing the boss portion when the adjacent ports communicate with each other.

However, an annular recessed groove is formed in the sliding portion (sliding surface) at the outer peripheral end of the boss portion, an annular packing for sealing between the spool hole and the seat portion is attached to the recessed groove, and the inner peripheral surface of the packing is brought into contact with the groove bottom surface of the recessed groove, whereby leakage of the compressed fluid through the gap between the sliding portion and the seat portion is prevented when communication between the ports is blocked.

However, if the compressed fluid flows into the recessed groove between the groove bottom surface of the recessed groove and the inner peripheral surface of the packing, the inner peripheral surface of the packing floats from the groove bottom surface of the recessed groove, and the packing is likely to be separated from the recessed groove, which may cause various disadvantages such as an increase in sliding resistance of the packing with respect to the valve seat portion.

Therefore, for example, as shown in patent document 1, various arrangements have been proposed mainly from the viewpoint of the form of the packing with respect to the mounting structure of the packing to the recessed groove in order to suppress the inflow of the compressed fluid between the groove bottom surface of the recessed groove and the inner peripheral surface of the packing.

Prior art documents

Patent document

Patent document 1 Japanese patent application laid-open No. 6-147337

Disclosure of Invention

Problems to be solved by the invention

The technical problem of the present invention is to suppress as much as possible the inflow of compressed fluid between the groove bottom surface of a recessed groove and the inner peripheral surface of a packing by improving the structure of the recessed groove in a spool valve type switching valve in which a boss portion of a spool valve is provided with the recessed groove to which the packing is attached.

In order to solve the above problems, the present invention is a spool-type switching valve including a spool hole, a spool, and a valve driving unit, the spool hole connecting at least a pair of flow paths through which a compressed fluid flows and extending in an axial direction; the slide valve is inserted into the slide valve hole movably in the axial direction; the valve driving unit operates the spool valve in the axial direction to switch the communication state between the flow paths, and the spool valve, a boss part as a valve part having an annular sliding part on the outer periphery of a shaft and a small diameter part having an outer diameter smaller than the boss part are formed adjacent to each other in the axial direction, an annular groove opened in the radial direction is provided around the sliding portion of the boss portion, an annular packing made of an elastic material is accommodated in the groove, an annular valve seat portion and an annular large diameter portion are formed on an inner surface of the spool hole so as to be adjacent to each other in an axial direction, the annular valve seat portion is a valve seat portion in which the boss portion is slidably fitted in the axial direction with the sliding portion facing the boss portion, the annular large diameter portion has an inner diameter larger than that of the valve seat portion, and the pair of flow passages are connected to both sides of the valve seat portion in the axial direction, and the communication state between the pair of flow passages can be switched to a state in which: a state in which the boss portion is disposed in the large diameter portion and the small diameter portion is disposed in the valve seat portion, and the pair of flow paths communicate with each other; and a pair of side wall surfaces, the pair of side wall surfaces being provided upright from an upstream end and a downstream end of the groove bottom surface and facing each other, the groove bottom surface of the groove having inclined surfaces, an axial length of the inclined surfaces being half or more than an axial length of the groove bottom surface, the inclined surfaces being continuously reduced in diameter from the upstream end to the downstream end, an inner peripheral surface of the packing being positioned at a pressure contact point defining an end portion of the inclined surface on the upstream end side with respect to the groove bottom surface, the pressure contact point being a pressure contact point of an end portion of the inclined surface on the upstream end side, the pressure contact point being a stress concentration And a pressure-bonding step of, when an angle formed by the inclined surface and the shaft is defined as α, setting an angle θ formed by a connecting surface between the pressure-bonding point and the upstream end in the bottom surface of the connecting groove and the shaft to be 0 ° ≦ θ ≦ α.

In this case, it is preferable that the groove has a cross section in which the inclined surface and the connecting surface of the groove bottom surface are formed linearly, and an angle α formed between the inclined surface and the shaft is in a range of 10 ° ≦ α. Preferably, the inner peripheral surface of the packing is in pressure contact with a pressure contact point of the groove bottom surface at a portion closer to the upstream end than the center thereof.

In the spool-type switching valve according to the present invention, it is preferable that the packing has a pair of side surfaces that are connected to both ends of the inner peripheral surface in the width direction and face away from each other, and that, in the recessed groove, a downstream side surface of the pair of side surfaces of the packing, which is disposed on the downstream side end side, is always in contact with a downstream side wall surface of the pair of side walls of the recessed groove, which is provided upright from the downstream side end of the groove bottom surface.

In addition, it is preferable that an inner peripheral surface of the packing in a cross section of the packing in a state of not being fitted in the recessed groove is formed in a straight line shape parallel to the shaft. In this case, it is more preferable that the cross section of the filler in a state of not being fitted in the pocket is formed to be bilaterally symmetrical with respect to a center line extending in a radial direction through a center of an inner peripheral surface thereof, and it is further preferable that the pair of side surfaces of the filler in a state of not being fitted in the pocket are respectively formed in a straight shape gradually approaching the center line from an inner peripheral side to an outer peripheral side.

Further, in the spool-type switching valve according to the present invention, it is preferable that the pair of side wall surfaces of the recessed groove extend in a direction orthogonal to the axis. In a state where the packing is mounted in the groove, an outer diameter of the packing is formed to be equal to or larger than an inner diameter of a valve seat portion of the spool hole, the flow paths connected to the spool valve are an air supply flow path, an output flow path, and an exhaust flow path, the output flow path is connected between the air supply flow path and the exhaust flow path in the axial direction, the pair of the flow paths is the output flow path and the exhaust flow path, the output flow path is an upstream side flow path through which the compressed fluid flows into the spool hole, and the exhaust flow path is a downstream side flow path through which the compressed fluid flows out of the spool hole.

ADVANTAGEOUS EFFECTS OF INVENTION

As described above, in the present invention, the groove bottom surface of the recessed groove in which the packing is attached in the boss portion of the spool valve has the inclined surface that is formed to have an axial length that is half or greater than an axial length of the groove bottom surface and that continuously decreases in diameter from the upstream side end side toward the downstream side end side, and the inner peripheral surface of the packing is pressed against the groove bottom surface at the pressure contact point that defines the end portion of the inclined surface on the upstream side end side with concentration of stress. When an angle formed by the inclined surface and the shaft is defined as α, an angle θ formed by a connecting surface connecting the pressure contact point and the upstream end in the groove bottom surface and the shaft is set to a range of 0 ≦ θ ≦ α.

Therefore, the compressed fluid is prevented from flowing between the groove bottom surface of the recessed groove and the inner peripheral surface of the packing as much as possible, and as a result, the packing can be prevented from coming off the recessed groove due to the inner peripheral surface of the packing floating from the groove bottom surface of the recessed groove, among various disadvantages caused by the inflow of the compressed fluid. Further, it is also expected to suppress other adverse effects such as an increase in sliding resistance.

Drawings

Fig. 1 is a schematic axial cross-sectional view of a spool-type switching valve according to an embodiment of the present invention, showing a state in which a spool is displaced to a first switching position.

Fig. 2 shows a state in which the spool is displaced to the second switching position in the spool-type switching valve of fig. 1.

Fig. 3 is an enlarged view of the M1 portion showing a main portion of the valve main body portion in the state of fig. 1, and shows a state in which the first boss portion has moved to an open position where the first output flow path and the first exhaust flow path communicate with each other.

Fig. 4 is an enlarged view of the M2 portion showing a main portion of the valve main body portion in the state of fig. 2, and shows a state in which the first boss portion has moved to a closed position at which communication between the first output flow path and the first exhaust flow path is blocked.

Fig. 5 is a cross-sectional view of the packing.

Fig. 6 is an enlarged view of the N-part of fig. 3, showing an example of a structure for attaching a packing to a groove of a boss part of a spool.

Fig. 7 is a view showing a modification of the packing attachment structure shown in fig. 6.

Fig. 8 shows simulation results regarding the stress distribution of the packing using the packing mounting structure shown in fig. 6, where (a) shows a state where the boss portion is at the open position and the fluid pressure is not applied, (b) shows a state where the boss portion is at the open position and the fluid pressure is applied, and (c) shows a state where the boss portion is at the closed position and the fluid pressure is applied.

Fig. 9 shows other simulation results regarding the stress distribution of the packing using the mounting structure of the packing shown in fig. 6.

Fig. 10 shows a simulation result of a stress distribution of the packing using the mounting structure of the packing shown in fig. 7.

Fig. 11 shows other simulation results regarding the stress distribution of the packing using the packing mounting structure shown in fig. 7.

Fig. 12 shows a reference result of a simulation regarding the stress distribution of the filler.

Fig. 13 shows a reference result of a simulation of a stress distribution of a packing using a conventional packing mounting structure.

Detailed Description

A spool valve type switching valve 1 according to an embodiment of the present invention includes a spool hole 7 extending in the direction of an axis L; an air supply flow path 8/output flow paths 9 and 10 and exhaust flow paths 11 and 12 connected to the spool hole 7; a spool 20 as a main valve slidably inserted into the spool hole 7 in the direction of the axis L; and a valve driving unit 5 for operating the spool 20. By displacing the spool 20 in the spool hole 7 by the valve drive unit 5, the connection state between the output flow paths 9 and 10 and the intake flow path 8 and the exhaust flow paths 11 and 12 can be selectively switched. Here, the air supply flow path 8 is configured to supply a compressed fluid such as compressed air from a fluid pressure source (for example, a compressor), not shown, to the spool hole 7, the output flow paths 9 and 10 are configured to output the compressed fluid supplied to the spool hole 7 to various fluid pressure devices (not shown) such as a fluid pressure actuator (for example, an air pressure cylinder) driven by the compressed fluid, and the exhaust flow paths 11 and 12 are configured to exhaust an exhaust gas from the fluid pressure devices to the outside such as the atmosphere.

Specifically, as shown in fig. 1 to 4, the spool valve type switching valve 1 is an electromagnetic valve (electromagnetic pilot valve type switching valve) and is composed of a valve main body 2 including the spool hole 7, an air supply flow path 8, output flow paths 9 and 10, exhaust flow paths 11 and 12, and a spool 20; a first adapter portion 3 and a second adapter portion 4 connected to both side end surfaces of the valve main body portion 2 in the direction of the axis L; and an electromagnetic pilot valve portion as the valve drive portion 5 connected to a side end surface of the first adapter portion 3 on the opposite side of the valve main body portion 2.

The valve main body 2 has a housing 6 integrally molded in a substantially rectangular parallelepiped shape from resin or metal, and the spool hole 7 penetrates between both end surfaces of the housing 6 in a longitudinal direction thereof. An output port A, B forming the output flow paths 9 and 10 is opened in a plane (upper surface) of the housing 6, and pipes to the fluid pressure device can be connected to the output ports A, B. On the other hand, an air supply port P forming the air supply passage 8 for connecting a passage (or pipe) from the fluid pressure source is opened in a bottom surface (lower surface) opposite to the plane; and exhaust ports EA and EB forming the exhaust flow paths 11 and 12 for connecting flow paths (or pipes) for discharging the exhaust gas returned from the fluid pressure device through the output port A, B to the outside.

Here, the output port A, B is connected to the spool hole 7 via output communication passages 9a and 10a having a smaller flow path cross-sectional area than the output port A, B, and the output flow paths 9 and 10 are formed by the output port A, B and the output communication passages 9a and 10 a. The air supply port P is connected to the spool hole 7 via an air supply communication passage 8a having a smaller flow path cross-sectional area than the air supply port P, and the air supply passage 8 is formed by the air supply port P and the air supply communication passage 8 a. Further, the exhaust ports EA and EB communicate with the spool hole 7 via exhaust communication passages 11a and 12a having a smaller flow passage cross-sectional area than the exhaust ports EA and EB, and the exhaust passages 11 and 12 are formed by the exhaust ports EA and EB and the exhaust communication passages 11a and 12 a.

More specifically, the spool-type switching valve 1 includes 1 air supply port P disposed at the center of the bottom surface of the housing 6; a first exhaust port EA and a second exhaust port EB disposed adjacent to each other on both sides of the air supply port P in the longitudinal direction of the bottom surface of the housing 6; and 5 ports of a first output port A and a second output port B provided in parallel in the longitudinal direction on the plane of the housing 6. Further, by turning off or on the electromagnetic pilot valve portion (valve drive portion) 5, the spool 20 can be selectively moved to 2 switching positions, namely, a first switching position (see fig. 1) in which the first output port a communicates with the first exhaust port EA while the intake port P communicates with the second output port B, and a second switching position (see fig. 2) in which the second output port B communicates with the second exhaust port EB while the intake port P communicates with the first output port a.

The inner surface of the spool hole 7 is formed by providing a first support surface 7a, a first flow path groove 70, a first seat surface 71, a second flow path groove 72, a second seat surface 73, a third flow path groove 74, a third seat surface 75, a fourth flow path groove 76, a fourth seat surface 77, a fifth flow path groove 78, and a second support surface 7b in this order from an opening portion of one side end surface to which the first adapter portion 3 is attached to an opening portion of the other side end surface to which the second adapter portion 4 is attached in the direction of the axis L, and they are formed in a ring shape around the axis L. That is, the annular valve seat surface (valve seat portion) and the annular flow channel groove (large diameter portion) as a recessed groove are formed on the inner surface of the spool hole 7 so as to be alternately adjacent to each other along the axis L.

At this time, the inner diameters D0 of the first and second support surfaces 7a, 7b and the first to fourth valve seat surfaces 71, 73, 75, 77 are formed to be equal to each other, the inner diameters D1 of the groove bottom surfaces of the first, third, and fifth flow path grooves 70, 74, 78 are formed to be equal to each other, and the inner diameters D2 of the groove bottom surfaces of the second and fourth flow path grooves 72, 76 are formed to be equal to each other. The inner diameter D1 is formed to be slightly larger than the inner diameter D2, and the inner diameters D1 and D2 of the groove bottom surfaces are formed to be larger than the inner diameter D0 such as the valve seat surface in a range smaller than the width dimension of the housing 6. Further, as shown in fig. 3 and 4, a tapered portion T is formed in the opening edge of the first flow path groove 70 connected to the first seating surface 71, both opening edges of the third flow path groove 74 connected to the second and third seating surfaces 73, 75, and an opening edge of the fifth flow path groove 78 connected to the fourth seating surface 77, so that the groove width of these flow path grooves is widened toward the opening side (inward in the radial direction).

The first support surface 7a and the second support surface 7b, which are formed by the inner surface of the spool hole 7, support one end portion (first pressed portion 20a) and the other end portion (second pressed portion 20b) of the spool 20 in an airtight and slidable manner. Further, the communication passage 11a of the first exhaust passage 11 is connected to the groove bottom surface of the first passage groove 70, the communication passage 9a of the first discharge passage 9 is connected to the groove bottom surface of the second passage groove 72, the communication passage 8a of the supply passage 8 is connected to the groove bottom surface of the third passage groove 74, the communication passage 10a of the second discharge passage 10 is connected to the groove bottom surface of the fourth passage groove 76, and the communication passage 12a of the second exhaust passage 12 is connected to the groove bottom surface of the fifth passage groove 78. Reference numeral 79 in the figure denotes a pilot valve fluid supply hole for supplying pilot valve fluid to the first adapter portion 3 or the second adapter portion 4 through the valve driving portion 5 by a pilot valve flow path not shown, and is always communicated with the air supply flow path 8.

On the other hand, the spool valve 20 is formed by arranging a first pressed portion 20a, a first annular recess 21, a first boss portion 22, a second annular recess 23, a second boss portion 24, a third annular recess 25, a third boss portion 26, a fourth annular recess 27, a fourth boss portion 28, a fifth annular recess 29, and a second pressed portion 20b, which is airtightly slidably fitted to the second support surface 7b, in this order from one end on the first adapter portion 3 side to the other end on the second adapter portion 4 side in the direction of the axis L, and they are formed in an annular shape with the axis L as the center. That is, the annular recessed portions (small diameter portions) and the boss portions as the valve portions are alternately formed along the axis L in the spool valve 20.

In this case, the outer shape of each of the boss portions 22, 24, 26, and 28 is formed in a substantially equilateral trapezoidal shape in the radial direction Y, in which the width in the axial L direction gradually decreases from the base ends connected to the adjacent annular concave portions to the annular sliding portions (sliding surfaces) formed by the outer peripheral ends, and is bilaterally symmetrical in the axial L direction about the central axis in the radial direction. As shown in fig. 3 and 4 and fig. 6 and 7, an annular recessed groove 50 is opened in the sliding surface of each of the boss portions 22, 24, 26 and 28, the annular recessed groove 50 has a groove bottom surface 51 formed by an inclined surface 52 and opens in the radial direction Y, and the annular packing 13 shown in fig. 5 is accommodated in the recessed groove 50 of each of the boss portions 22, 24, 26 and 28. However, since the flow of the compressed fluid passing through the first and second boss portions 22, 24 and the third and fourth boss portions 26, 28 is in the opposite direction (i.e., bilaterally symmetrical), the inclination directions of the groove bottom surfaces 51 are also in the opposite directions in the concave groove 50 of the first and second boss portions 22, 24 and the concave groove 50 of the third and fourth boss portions 26, 28.

By doing so, when the boss portion is slidably fitted to the valve seat portion of the spool hole 7 (that is, disposed at the position of the valve seat surface) and the sliding portion (sliding surface) at the outer peripheral end thereof faces the valve seat surface, the gap formed between the sliding portion of the boss portion and the valve seat surface of the spool hole 7 can be sealed by the packing 13, and leakage of the compressed fluid through the gap can be suppressed or prevented as much as possible.

That is, in the present embodiment, in a state where the sealing member such as the packing 13 is not attached, the outer diameters (outer diameters of the sliding portions) D3 of the first and second pressed portions 20a and 20b and the first to fourth boss portions 22, 24, 26, and 28 are formed to be equal to each other, the outer diameters (outer diameters of the small diameter portions) D4 of the first to fifth annular recessed portions 21, 23, 25, 27, and 29 are formed to be equal to each other, and the outer diameter D3 of the boss portion is formed to be slightly smaller than the inner diameter D0 such as the valve seat surface and to be larger than the outer diameter D4 of the annular recessed portion.

The first adapter portion 3 has a first cylinder hole 30 and a first piston 31 in the axis L, the first cylinder hole 30 is formed to have a larger diameter than the spool hole 7 and is open on the valve body portion 2 side, and the first piston 31 is air-tightly fitted in the cylinder hole 30 so as to be slidable in the axis L direction. That is, the cylinder bore 30 is hermetically divided by the piston 31 into a first chamber 30a on the valve drive unit 5 side and a second chamber 30b on the valve main body 2 side with respect to the piston 31. The first piston 31 integrally includes a first pressing portion 31a disposed coaxially with the spool 20 on the valve body 2 side. The first pressing portion 31a is formed smaller in diameter than the first support surface 7a of the spool hole 7 and abuts against an end surface of the first pressed portion 20a of the spool 20. The first chamber 30a is connected to a pilot valve of the valve driving unit 5, and the second chamber 30b is always open to the atmosphere. In fig. 1, reference numeral 32 denotes a manual operation portion which is pushed in by an external manual operation to discharge the compressed fluid filled in the first chamber 30 a.

On the other hand, the second adapter portion 4 has a second cylinder hole 40 and a second piston 41 in the axis L, and the second cylinder hole 40 is formed larger in diameter than the spool hole 7 and smaller in diameter than the first cylinder hole 30, and opens on the valve body portion 2 side; the second piston 41 is air-tightly fitted in the cylinder hole 40 so as to be slidable in the direction of the axis L. That is, the cylinder bore 40 is air-tightly partitioned by the piston 41 into a first chamber 40a on the valve main body 2 side of the piston 41 and a second chamber 40b on the opposite side thereof. The diameter of the first piston 31 is formed larger than the diameter of the second piston 41, and the pressure receiving area of the first piston 31 on the first chamber 30a side is larger than the pressure receiving area of the second piston 41 on the second chamber 40b side.

The second piston 41 integrally includes a second pressing portion 41a disposed coaxially with the spool 20 on the valve body 2 side. The second pressing portion 41a is formed smaller in diameter than the second support surface 7b of the spool hole 7 and abuts against an end surface of the second pressed portion 20b of the spool 20. The first chamber 40a of the second cylinder bore 40 communicates with the second chamber 30b of the first cylinder bore 30 through a through hole 20c penetrating the center of the spool 20 in the direction of the axis L, and is always open to the atmosphere. On the other hand, the second chamber 40b is always in communication with the pilot fluid supply hole 79 and is always pressurized by the pilot fluid. Therefore, the spool 20 is always biased toward the first adapter 3 side (i.e., the first piston side) by the second piston 41 in the direction of the axis L.

Further, the support surfaces, the flow path grooves, and the valve seat surfaces of the spool hole 7, the pressed portions, the boss portions, and the annular recessed portions of the spool 20, and the cylinder holes 30 and 40 and the pistons 31 and 41 may be formed in an elliptical or annular shape in a cross section perpendicular to the axis L, in addition to a circular shape. Therefore, in the present application, for convenience, in the configuration in which the axis L is annularly surrounded, a chord that crosses the axis L at right angles is uniformly referred to as a "diameter", and a distance from the axis L to the outer periphery is uniformly referred to as a "radius".

Next, the operation of the spool-type switching valve 1 will be described with reference to fig. 1 to 4. First, as shown in fig. 1, in a state where the electromagnetic pilot valve constituting the valve driving portion 5 is off, the first chamber 30a of the first cylinder hole 30 is opened to the atmosphere. Therefore, the second piston 41 moves the first piston 31 together with the spool 20 toward the stroke end of the first chamber 30a by the pressing force thereof, and as a result, the spool 20 is switched to the first switching position. At this time, in the axial L direction, the first boss portion 22 of the spool valve 20 is disposed at the position of the first flow passage groove 70 of the spool hole 7, the second boss portion 24 is disposed at the position of the second valve seating surface 73, the third boss portion 26 is disposed at the position of the third flow passage groove 74, and the fourth boss portion 28 is disposed at the position of the fourth valve seating surface 77.

That is, in the spool hole 7, the communication between the first discharge flow path 9 and the supply flow path 8 is blocked by the second boss portion 24, and the communication between the second discharge flow path 10 and the second exhaust flow path 12 is blocked by the fourth boss portion 28. In addition, due to the positional relationship between the spool hole 7 and the spool valve 20, the first output flow path 9 and the first exhaust flow path 11 communicate with each other through the spool hole 7, and the second output flow path 10 and the supply flow path 8 communicate with each other through the spool hole 7 similarly. At this time, the second exhaust passage 12 is closed in the spool hole 7.

On the other hand, as shown in fig. 2, in a state where the electromagnetic pilot valve constituting the valve driving portion 5 is on, the pilot valve fluid is supplied to the first chamber 30a of the first cylinder bore 30 by the valve driving portion 5. Therefore, the first piston 31 moves the second piston 41 together with the spool 20 toward the stroke end of the second cylinder bore 40 on the second chamber 40b side against the pressing force of the second piston 41 by the pressing force thereof, and as a result, the spool 20 is switched to the second switching position. At this time, in the direction of the axis L, the first boss portion 22 of the spool valve 20 is disposed at the position of the first seating surface 71 of the spool hole 7, the second boss portion 24 is disposed at the position of the third flow path groove 74, the third boss portion 26 is disposed at the position of the third seating surface 75, and the fourth boss portion 28 is disposed at the position of the fifth flow path groove 78.

That is, in the spool hole 7, the communication between the first discharge flow path 9 and the first exhaust flow path 11 is blocked by the first boss portion 22, and the communication between the second discharge flow path 10 and the supply flow path 8 is blocked by the third boss portion 26. In addition, due to the positional relationship between the spool hole 7 and the spool valve 20, the first output flow path 9 and the supply flow path 8 communicate with each other through the spool hole 7, and the second output flow path 10 and the second exhaust flow path 12 also communicate with each other through the spool hole 7. At this time, the first exhaust passage 11 is closed in the spool hole 7.

Next, the structure of attaching the packing 13 to the annular recessed groove 50 in the spool-type switching valve 1 and the operational effects thereof will be specifically described with reference to fig. 3 to 13. In the present embodiment, the structure of the valve body 2 is substantially bilaterally symmetrical with respect to the center in the direction of the axis L, and the flow of the compressed fluid between the flow passages (ports) is also substantially bilaterally symmetrical. Therefore, in order to avoid redundant description, the structure of attaching the packing 13 to the recessed groove 50 and the operational effects thereof will be mainly described with respect to the flow of the compressed fluid from the first discharge flow path 9 to the first discharge flow path 11 and the flow of the compressed fluid from the supply flow path 8 to the first discharge flow path 9, which are caused by the displacement of the spool 20.

As shown in fig. 5, in the present embodiment, the annular packing 13 has an inner circumferential surface 14 around the axis L; a pair of side surfaces 15a, 15b having one end connected to both ends of the inner peripheral surface in the axial direction (width direction) and extending in the radial direction Y orthogonal to the axial direction L; and an outer peripheral surface (sealing surface) 16 connecting the other ends of the pair of side surfaces 15a and 15b to each other. The packing 13, which is not mounted in the recessed groove 50 of the boss portion, is formed in a tapered shape (wedge shape) in a cross section which is symmetrical with respect to a central axis extending in the radial direction Y through the center of the inner peripheral surface 14 and in which a width in the axis L direction gradually decreases from the inner peripheral side toward the outer peripheral side.

Specifically, the inner peripheral surface 14 is formed in a ring shape having a diameter D5 around the axis L and extends flat (i.e., linearly in cross section) along the axis L, the pair of side surfaces 15a and 15b are formed as flat (i.e., linearly in cross section) inclined surfaces inclined in a direction approaching the central axis from the inner diameter side to the outer diameter side so as to face away from each other, and the sealing surface 16 formed by the outer peripheral surface is formed as a curved surface, preferably an arc surface, convex in the radial direction Y. In addition, in the cross section, the maximum width Wp of the filler 13 is formed smaller than the height Hp thereof. The material of the filler 13 is not particularly limited as long as it is a rubber elastic material that exhibits a sealing function, and for example, nitrile rubber, fluororubber, or the like can be used.

Hereinafter, the structure for mounting the packing 13 in the spool valve type switching valve 1 of the present embodiment will be described in more detail based on an example in which the packing 13 is mounted in the conventional recessed groove 50A formed in the first boss portion 22 and an example in which the packing 13 is mounted in the recessed groove 50 of the present embodiment formed in the boss portion 22.

As described above, the first exhaust flow path 11 and the first output flow path 9 are connected to the portions (the first flow path groove 70 and the second flow path groove 72) on both sides in the axial L direction of the first seat surface 71 that is in contact with and separated from each other with the first boss portion 22 interposed therebetween in the inner surface of the spool hole 7. In addition, in a state where the spool 20 is located at the first switching position, as shown in fig. 3, the boss portion 22 is located at an "open position (a range of the flow path groove 70 in the axis L direction)" where the exhaust flow path 11 and the output flow path 9 communicate with each other, and in a state where the spool 20 is located at the second switching position, as shown in fig. 4, the boss portion 22 is located at a "closed position (a range of the seat surface 71 in the axis L direction)" where the exhaust flow path 11 and the output flow path 9 communicate with each other. That is, in the first boss portion 22, the output flow path 9 through which the compressed fluid flows into the spool hole 7 is a flow path connected to the "upstream side" of the flow of the compressed fluid in the direction of the axis L, and the exhaust flow path 11 through which the compressed fluid is discharged from the spool hole 7 is a flow path connected to the "downstream side" of the flow of the compressed fluid in the direction of the axis L.

Fig. 13 shows a state in which the packing 13 is attached to a conventional general pocket groove 50A formed in the first boss portion 22, and this conventional pocket groove 50A is formed by a groove bottom surface 51A formed in a ring shape around an axis L and extending flatly (i.e., linearly in cross section) along the axis L, and a pair of side wall surfaces 56 and 57 provided upright from both ends 54 and 55 of the groove bottom surface 51A in the axis L direction in the radial direction Y and facing each other. A sliding portion (sliding surface) 22a formed by the outer peripheral surface of the boss portion 22 and a pair of side wall surfaces 56 and 57 formed as mutually parallel planes intersect at a right angle, whereby the opening of the recessed groove 50A is formed in the outer peripheral surface of the boss portion 22. That is, the recessed groove 50A is formed in a rectangular shape having a groove width Wg in the direction of the axis L, which is symmetrical in the horizontal plane about a central axis extending in the radial direction Y through the center of the groove bottom surface 51A.

Here, in fig. 13, when the flow of the compressed fluid in the direction of the axis L is viewed, the right side in the direction of the axis L is an upstream side of a flow path (first output flow path 9) in which the compressed fluid flows into the spool hole 7, and the left side in the direction of the axis L is a downstream side of a flow path (first exhaust flow path 11) in which the compressed fluid is discharged from the spool hole 7. Therefore, in the concave groove 50A of the first boss portion 22, the end on the right side in the drawing among the both ends in the axial L direction of the groove bottom surface 51A becomes the upstream side end 54, and the end on the left side in the drawing becomes the downstream side end 55. Of the pair of side wall surfaces 56, 57, the side wall surface disposed on the right side in the figure is the upstream side wall surface 56, and the side wall surface disposed on the left side in the figure is the downstream side wall surface 57. In the packing 13, the side surface of the pair of side surfaces 15a and 15b disposed on the right side in the drawing is an upstream side surface 15a, and the side surface disposed on the left side in the drawing is a downstream side surface 15 b.

The diameter Dg of the groove bottom surface 51A of the recessed groove 50A is formed larger than the original inner diameter (diameter of the inner circumferential surface 14) D5 of the packing 13 in a state where the packing is not mounted in the recessed groove 50A. That is, the circumferential length of the inner circumferential surface 14 of the packing 13 is formed shorter than the circumferential length of the groove bottom surface 51A. Therefore, in a state where the packing 13 is fitted in the groove 50A, the packing 13 made of a rubber elastic material is expanded in the circumferential direction, and the inner peripheral surface 14 thereof is elastically pressed against the groove bottom surface 51A. In the state where the packing 13 is fitted in the recessed groove 50A, the outer diameter Dp of the packing 13 is larger than the outer diameter D3 of the sliding surface 22a of the boss portion 22, and is equal to or larger than the inner diameter D0 of the seat surface 71. Therefore, the seal surface 16 of the packing 13 protrudes in the radial direction Y from the sliding surface 22a of the boss portion 22, and slidably abuts against the valve seat surface 71 of the spool hole 7 when the boss portion 22 is located at the closed position. Further, the width Wg of the groove 50A becomes larger than the original width Wp of the filler (see fig. 5).

In fig. 13(a) to (c), the curves shown in the cross section of filler 13 are isostress lines showing the state of internal stress (internal compressive stress) of filler 13, and the region with dots (hereinafter referred to as "dot region") shows the region with the smallest internal stress (including tensile stress) in each figure, and the stress range of this dot region is common between the figures. In the non-dotted region (hereinafter referred to as "non-dotted region"), the stress widths between adjacent equal stress lines are equal. Therefore, the narrower the distance interval between adjacent equal stress lines, the greater the rate of increase in internal stress. Further, the more non-point regions surrounded by mutually adjacent equi-stress lines traverse with the point region as a starting point, the larger the internal stress.

Fig. 13(a) shows a simulation result of the mounted state of the packing 13 and the distribution of the internal stress thereof in a state where the boss portion 22 is in the open position and the fluid pressure of the compressed fluid does not act on the packing 13 (i.e., a state where the compressed fluid does not flow around the boss portion 22). The inner peripheral surface 14 is pressed against the groove bottom surface 51A substantially uniformly over the entire width direction, and the internal stress generated in the inner peripheral surface 14 portion, that is, the surface pressure acting from the groove bottom surface 51A to the inner peripheral surface 14 is dispersed substantially uniformly over the entire width direction and becomes small.

Similarly, (b) shows a simulation result of a state in which the boss portion 22 is in the above-described open position, and the compressed fluid having the pressure Ps (0.7 MPa) flows from the upstream side (the first output flow path 9 side) to the downstream side (the first exhaust flow path 11 side) of the boss portion 22, and the fluid pressure thereof acts on the packing 13. In the above (a), since the surface pressure acting on the inner peripheral surface 14 is dispersed and decreased substantially uniformly over the entire width direction, the entire inner peripheral surface 14 floats from the groove bottom surface 51A by the difference between the force acting on the packing 13 in the radial direction Y by the compressed fluid and the force acting on the packing 13 in the radial direction Y by the fluid pressure of the compressed fluid flowing between the inner peripheral surface 14 and the groove bottom surface 51A in the recessed groove 50A (force in the radial direction < force in the radial direction). As a result, the amount of protrusion of the outer peripheral portion of the packing 13 from the sliding surface 22a becomes larger than that in the state (a). Therefore, for example, in the process of displacing the boss portion 22 from the open position to the closed position in accordance with the displacement of the spool 20, when the outer peripheral portion of the packing 13 is seated on the seat surface 71, there is a risk that the packing 13 is pulled out from the pocket 50A.

Further, (c) shows a simulation result of a state in which the boss portion 22 is in the closed position, the sealing surface of the packing 13 abuts against the valve seat surface 71 (that is, the compressed fluid does not flow around the boss portion 22), and the fluid pressure Ps of the compressed fluid acts on the packing 13 from the upstream side. Here, the end of the groove bottom surface 51A on the upstream side end 54 side (i.e., the upstream side of the compressed fluid) of the inner peripheral surface 14 flows in between the groove bottom surface 51A and the compressed fluid, and floats. Further, if such floating occurs, there is a risk that the surface pressure acting between the seal surface 16 of the packing 13 and the valve seat surface 71 becomes large, and the sliding resistance of the packing 13 increases, and as a result, there is a fear that the life of the packing is shortened.

In the second boss portion 24, the supply flow path 8 through which the compressed fluid flows into the spool hole 7 is a flow path connected to the "upstream side" of the flow of the compressed fluid in the direction of the axis L, and the first discharge flow path 9 through which the compressed fluid flows out of the spool hole 7 is a flow path connected to the "downstream side" of the flow of the compressed fluid in the direction of the axis L. That is, with respect to the first boss portion 22 and the second boss portion 24, the positional relationship between the upstream side and the downstream side in the direction of the axis L, that is, the flow direction of the compressed fluid in the direction of the axis L is the same (from the right side to the left side in the drawing). Therefore, the packing 13 attached to the second boss portion 24 can obtain substantially the same result as the packing 13 of the first boss portion 22 shown in fig. 13(a) to (c), and therefore, there is a possibility that substantially the same disadvantage as the packing 13 of the first boss portion 22 described above occurs.

However, since the packing 13 of the first boss portion 22 is seated on the first valve seat surface 71 while moving from the downstream side to the upstream side (from the left to the right in fig. 13) of the compressed fluid, the direction of the fluid pressure Ps acting on the packing 13 and the direction of the collision force acting on the packing 13 at the time of seating coincide. In contrast, since the packing 13 of the second boss portion 24 is seated on the second seat surface 73 while moving from the upstream side to the downstream side of the compressed fluid (in fig. 13, in the rightward direction, in the leftward direction), the direction of the fluid pressure Ps acting on the packing 13 and the direction of the collision force acting on the packing 13 at the time of seating are in an opposite relationship. Therefore, the packing 13 of the first boss portion 22 becomes easier to pull out than the second boss portion 24.

Therefore, in the present embodiment, as shown in fig. 6 and 7, the inclined surface 52 is formed on the groove bottom surface 51 of the recessed groove 50 for the packing 13 in each boss portion, so that the surface pressure acting between the groove bottom surface 51 of the recessed groove 50 and the inner circumferential surface 14 of the packing 13 is concentrated to a specific portion (that is, the specific portion of the inner circumferential surface 14 of the packing 13 is intensively pressure-contacted with the specific portion of the groove bottom surface 51 along with the maximum value of the surface pressure), and the compressed fluid is prevented from flowing between the inner circumferential surface 14 and the groove bottom surface 51. At this time, as will be described later in detail, concentrated stress (stress concentration) occurs at the specific portion of the inner peripheral surface 14 due to pressure contact with the groove bottom surface 51.

The recessed groove 50 is formed by a groove bottom surface 51 formed annularly around the axis L and a pair of side wall surfaces 56 and 57 provided upright from both ends 54 and 55 of the groove bottom surface 51 in the axis L direction in the radial direction Y and opposed to each other. A sliding portion (sliding surface) 22a formed by the outer peripheral surface of the boss portion 22 and a pair of side wall surfaces 56 and 57 formed as mutually parallel planes intersect at a right angle, whereby the opening of the recessed groove 50 is formed in the outer peripheral surface of the boss portion 22. The original maximum width Wp of the filler 13 shown in fig. 5 is smaller than the groove width Wg of the groove 50 in the axial L direction, and is formed larger than half of the groove width Wg.

Here, in fig. 6 to 12 as well, when the flow of the compressed fluid in the direction of the axis L is viewed, the right side in the direction of the axis L is an upstream side of a flow path (first output flow path 9) through which the compressed fluid flows into the spool hole 7, and the left side in the direction of the axis L is a downstream side of a flow path (first exhaust flow path 11) through which the compressed fluid is discharged from the spool hole 7, as in the case of fig. 13. Therefore, in the concave groove 50 of the first boss portion 22, the end on the right side in the drawing among the two ends in the axial L direction of the groove bottom surface 51 becomes the upstream side end 54, and the end on the left side in the drawing becomes the downstream side end 55. Of the pair of side wall surfaces 56, 57, the side wall surface disposed on the right side in the figure is the upstream side wall surface 56, and the side wall surface disposed on the left side in the figure is the downstream side wall surface 57. The packing 13 is also configured such that the side surface of the pair of side surfaces 15a and 15b disposed on the right side in the figure is an upstream side surface 15a, and the side surface disposed on the left side in the figure is a downstream side surface 15 b.

As shown in fig. 6 and 7, the inclined surface 52 included in the groove bottom surface 51 of the recessed groove 50 is formed to have a length W1 in the axial L direction that is half or greater than a length Wg in the axial L direction of the groove bottom surface 51 (i.e., a groove width of the recessed groove 50), and is continuously (linearly in cross section in the present embodiment) reduced in diameter from the upstream side end 54 side toward the downstream side end 55 side.

The inclined surface 52 has a first end 52a on the upstream side end 54 side and a second end 52b on the downstream side end 55, and forms an acute angle α with respect to the axis. The first end 52a is defined by a pressure contact point S at which a specific portion of the inner peripheral surface 14 of the packing 13 is brought into pressure contact with the groove bottom surface 51 along with a maximum value of the surface pressure (i.e., along with concentrated stress (stress concentration)), and the second end 52b is defined by a downstream side end 55 of the groove bottom surface 51.

That is, the diameter Ds of the groove bottom surface 51 at the pressure contact point S (the first end 52a of the inclined surface 52) is formed larger than the original diameter D5 of the inner peripheral surface 14 of the packing 13 shown in fig. 5. Therefore, in a state where the packing 13 is fitted in the pocket 50, the packing 13 made of a rubber elastic material is expanded in the circumferential direction, and is elastically and intensively pressed against the pressure contact point S of the groove bottom surface 51 at a portion on the upstream side surface 15a from the center of the inner circumferential surface 14.

The groove bottom surface 51 further has a connecting surface 53 connecting the pressure contact point S and an upstream side end 54. The connecting surface 53 is formed in a linear shape having an acute angle θ with respect to the axis L in the cross section, the length in the direction of the axis L is W2, and the groove width Wg of the recessed groove 50 is equal to the sum of the axial length W1 of the inclined surface 52 and the axial length W2 of the connecting surface 53. In fig. 6, the angle θ of the coupling surface 53 with respect to the axis L is equal to the inclined surface 52 and is α, and the groove bottom surface 51 is inclined at a constant angle from the upstream side end 54 to the downstream side end 55. In fig. 7, the angle θ is 0 °. However, the angle θ of the connection surface 53 is not limited to these 2 angles, and may be in a range of 0 ° ≦ θ ≦ α. The packing 13 having the inner peripheral surface 14 pressed against the groove bottom surface 51 in this manner is mounted in the recessed groove 50 in a state where the downstream side surface 15b is always in contact with the downstream side wall surface 57 of the recessed groove 50.

Further, as in the case of fig. 13, the outer diameter Dp of the packing 13 is larger than the outer diameter D3 of the sliding surface 22a of the boss portion 22, and is the same as or larger than the inner diameter D0 of the seat surface 71. Therefore, the seal surface 16 of the packing 13 protrudes in the radial direction Y from the sliding surface 22a of the boss portion 22, and slidably abuts against the valve seat surface 71 of the spool hole 7 when the boss portion 22 is located at the closed position.

Fig. 8 to 11 are iso-stress line graphs showing simulation results of distribution of internal stress (internal compressive stress) of the packing 13 mounted in the pocket 50 of the boss portion 22 in the present embodiment, and as described above with respect to fig. 13, the "dot region" shows a region (including tensile stress) where the internal stress is minimum in each graph, and the stress range of this dot region is common between the stress line graphs including fig. 13. In the non-dot region, the stress widths of the adjacent equal stress lines are also equal to each other, and are common between the stress lines including fig. 13.

In fig. 8 to 11, (a) shows a state in which the boss portion 22 is in the open position and the fluid pressure of the compressed fluid is not applied to the packing 13 (i.e., a state in which the compressed fluid does not flow around the boss portion 22). (b) A simulation result showing a state in which the boss portion 22 is at the above-described open position, and compressed fluid having a pressure Ps (═ 0.7MPa) flows from the upstream side (the first output flow path 9 side) to the downstream side (the first exhaust flow path 11 side) of the boss portion 22, and the fluid pressure thereof acts on the packing 13 is shown. (c) This state is shown in which the boss portion 22 is in the above-described closed position, the sealing surface of the packing 13 is in contact with the valve seat surface 71 (i.e., the compressed fluid does not flow around the boss portion 22), and the fluid pressure Ps of the compressed fluid acts on the packing 13 from the upstream side.

First, fig. 8 shows an embodiment in which both the inclination angle α of the inclined surface 52 of the groove bottom surface 51 and the inclination angle θ of the connecting surface 53 are 10 °. As is clear from (a) in which the fluid pressure does not act on the packing 13, concentrated stress is generated at the inner peripheral portion of the packing 13 at the pressure contact point S of the groove bottom surface 51, and the inner peripheral surface 14 is brought into pressure contact with the pressure contact point S in accordance with the maximum value of the surface pressure. In any of (b) and (c) in which the fluid pressure acts on the packing 13, the pressure-contact state between the inner circumferential surface 14 and the groove bottom surface 51 is maintained, and the inner circumferential surface 14 does not float from the groove bottom surface 51. Instead, in (b), a greater maximum surface pressure acts than in (a). That is, it can be said that the concentrated surface pressure generated at the pressure contact point S of (a) with the maximum value prevents the compressed fluid from flowing into the space between the inner circumferential surface 14 of the packing 13 and the groove bottom surface 51.

Next, fig. 9 shows an embodiment in which both the inclination angle α of the inclined surface 52 of the groove bottom surface 51 and the inclination angle θ of the connecting surface 53 are 20 °. As is clear from (a) in which the fluid pressure does not act on the packing 13, a large concentrated stress is generated at the pressure contact point S of the groove bottom surface 51 in the inner peripheral portion of the packing 13 as compared with the case of fig. 8, and the inner peripheral surface 14 is brought into pressure contact with the pressure contact point S along with a larger maximum value of the surface pressure. Further, as in fig. 8, in any of (b) and (c) in which the fluid pressure acts on the packing 13, the pressure-contact state between the inner peripheral surface 14 and the groove bottom surface 51 is maintained, and the inner peripheral surface 14 does not float from the groove bottom surface 51. Here, in (b), a larger maximum surface pressure acts than in (a). That is, it can be said that the inflow of the compressed fluid between the inner circumferential surface 14 of the packing 13 and the groove bottom surface 51 is more strongly prevented by the larger surface pressure of the concentration of the maximum value generated at the pressure contact point S in (a). In addition, the surface pressure acting between the valve seat surfaces 71 of the packing 13 is also reduced as compared with fig. 12 (c).

Fig. 10 shows an embodiment in which the axial length W1 of the inclined surface 52 is 3/4 of the groove width Wg of the groove 50 when the inclination angle α of the inclined surface 52 of the groove bottom surface 51 is 20 ° and the inclination angle θ of the connecting surface 53 is 0 °. As is clear from (a) in which the fluid pressure does not act on the filler 13, the pressure contact point S at the refraction point on the groove bottom surface 51 generates a larger concentrated stress at the inner peripheral portion of the filler 13 than in the case of fig. 8, and the inner peripheral surface 14 is brought into pressure contact with the pressure contact point S along with a larger maximum value of the surface pressure. In any of (b) and (c) in which the fluid pressure acts on the packing 13, the pressure-bonded state between the inner peripheral surface 14 and the groove bottom surface 51 is maintained, and the inner peripheral surface 14 does not float from the groove bottom surface 51. In addition, in (b), a larger maximum surface pressure acts as compared with (a). That is, similarly to the case of fig. 9, it can be said that the inflow of the compressed fluid into between the inner peripheral surface 14 of the packing 13 and the groove bottom surface 51 is more strongly prevented by the concentrated larger surface pressure with the maximum value generated at the pressure contact point S of (a). In addition, as in fig. 9(c), the surface pressure acting between the packing 13 and the valve seat surface 71 is also reduced as compared with fig. 12 (c).

Next, fig. 11 shows an embodiment in which the axial length W1 of the inclined surface 52 is 1/2 of the groove width Wg of the concave groove 50 when the inclination angle α of the inclined surface 52 of the groove bottom surface 51 is 20 ° and the inclination angle θ of the connecting surface 53 is 0 °. As is clear from the fluid pressure not acting on the filler 13(a), the pressure contact point S at the refraction point on the groove bottom surface 51 generates a larger concentrated stress at the inner peripheral portion of the filler 13 than in the case of fig. 8, and the inner peripheral surface 14 is brought into pressure contact with this pressure contact point S along with a larger maximum value of the surface pressure. In any of (b) and (c) in which the fluid pressure acts on the packing 13, the pressure-bonded state between the inner peripheral surface 14 and the groove bottom surface 51 is maintained, and the inner peripheral surface 14 does not float from the groove bottom surface 51. Here, in (b), a larger maximum surface pressure acts than in (a). That is, similarly to the cases of fig. 9 and 10, it can be said that the inflow of the compressed fluid between the inner peripheral surface 14 of the packing 13 and the groove bottom surface 51 is more strongly prevented by the larger surface pressure resulting from the concentration of the local maximum value generated at the pressure contact point S in (a).

Fig. 12 shows a reference example in which the inclination angle α of the inclined surface 52a of the groove bottom surface 51B is 20 °, the inclination angle θ of the connecting surface 53a is 0 °, and the axial length W1 of the inclined surface 52a is 1/4 of the groove width Wg of the groove 50B in the groove 50B. In this case, as in the conventional example of fig. 13, the internal stress generated in the portion of the inner peripheral surface 14 of the packing 13, that is, the surface pressure acting on the inner peripheral surface 14 from the groove bottom surface 51B is reduced by being dispersed substantially uniformly over the entire width direction, depending on (a) of the packing 13 on which the fluid pressure does not act. Therefore, in (B) in which the fluid pressure of the compressed fluid is applied to the packing 13, the compressed fluid flows between the inner peripheral surface 14 and the groove bottom surface 51B, and the inner peripheral surface 14 floats from the groove bottom surface 51B. Therefore, as in the conventional example of fig. 13, the packing 13 may be pulled out from the concave groove 50B in a process of displacing the boss portion 22 from the open position to the closed position.

From the above simulation results, it can be said that the inclination angle α of the inclined surface 52 is preferably 10 ° or more, and more preferably 20 ° or more. The length W1 of the inclined surface 52 in the axial L direction is preferably 1/2 or more of the groove width Wg, and more preferably 3/4 or more of the groove width Wg.

While one embodiment of the spool-type switching valve of the present invention has been described above, the present invention is not limited to the above-described embodiments, and it is needless to say that various design changes can be made without departing from the scope of the claims.

In the present embodiment, the inclined surface 52 is provided on the groove bottom surface 51 of all the concave grooves 50 in the first to fourth boss portions 22, 24, 26, 28, but the inclined surface 52 may be provided only on the groove bottom surface 51 of the first and fourth boss portions 22, 28 where the removal of the packing 13 is likely to occur.

The second end 52b of the inclined surface 52 need not be defined by the downstream end 55 of the groove bottom surface 51.

Further, the packing 13 in the state of being mounted in the pocket 50 may have an outer diameter Dp slightly smaller than the diameter of the seat surface, and the seal surface 16 may be brought into contact with the seat surface by deformation due to fluid pressure.

Description of the symbols

1: slide valve type switching valve (electromagnetic valve)

2: valve body

3: first adapter part

4: second adapter part

5: valve drive part (electromagnetic pilot valve part)

6: outer casing

7: spool bore

8: air supply flow path

9: first output flow path

10: second output flow path

11: first exhaust flow path

12: second exhaust gas flow path

13: filler material

14: inner peripheral surface of the packing

15a upstream side surface

15b downstream side surface

16: sealing surface

20: slide valve

21: first annular recess (Small diameter part)

22: first boss part

23: second annular recess (Small diameter part)

24: second boss part

25: third annular recess (Small diameter part)

26: third boss part

27: fourth annular recess (Small diameter part)

28: fourth boss part

29: fifth Ring recess (Small diameter part)

30: first cylinder hole

31: first piston

40: second cylinder hole

41: second piston

50: groove for installing filler

51: bottom surface of groove

52: inclined plane

α: angle of inclined plane

53: connecting surface

θ: angle of the connecting surface

54: upstream side end

55: downstream side end

56: upstream side wall surface

57: side wall surface on downstream side

70: first flow channel groove (Large diameter part)

71: first valve seat (valve seat)

72: second flow channel groove (Large diameter part)

73: second valve seat surface (valve seat part)

74: third flow channel groove (Large diameter part)

75: third valve seat surface (valve seat)

76: fourth flow channel groove (Large diameter part)

77: fourth valve seat (valve seat)

78: fifth flow channel groove (Large diameter part)

A: first output port

B: second output port

P: gas supply port

EA: first exhaust port

EB: second exhaust port

D0: inner diameter of valve seat surface and support surface

Inner diameters of D1 and D2 flow channel grooves (large diameter portions)

D3: outer diameter of boss part

D4: outer diameter of annular recess (small diameter part)

D5: original inner diameter of the packing

And Dp: the groove に is mounted on the outer diameter of した packing

Ds: groove bottom diameter in press contact point S

S: pressure contact

And (Wp): width in cross section of packing

Wg: width in cross section of groove

W1: axial length of inclined surface in groove bottom surface

W2: axial length of connecting surface in groove bottom surface

L: shaft

Y: and (4) the radial direction.