JP7108774B1 - spool valve - Google Patents

Abstract

An object of the present invention is to stabilize the operation of a spool valve. A spool (20) of a spool valve (100) is partially connected to a tank passage (15A) in a neutral position where communication of a rod side passage (12) and a bottom side passage (13) with tank passages (15A, 15B) and a bridge passage (14) is cut off. Having a first land portion 21 and a second land portion 22 facing the tank passage 15A in the neutral position, the first land portion 21 and the second land portion 22 facing the tank passage 15A have a predetermined first clearance R1 with respect to the housing hole 11. A sliding first large diameter portion 21A and a second large diameter portion 22A, and a second clearance that at least partially faces the tank passage 15A in the neutral position and is larger than the first large diameter portion 21A and the second large diameter portion 22A. It has a first small diameter portion 21B and a second small diameter portion 22B that move within the accommodation hole 11 by means of R2. [Selection drawing] Fig. 2

Description

The present invention relates to spool valves.

Patent Document 1 discloses a valve housing provided with a spool sliding hole and a plurality of oil passages communicating with the spool sliding hole, and a plurality of oil passages that are inserted into the spool sliding hole of the valve housing and communicate with each other. A spool valve is disclosed that includes a shut-off spool. In this spool valve, oil grooves forming the oil passage on the tank side, the oil passage on the pump side, and the oil passage on the actuator side are formed in the valve housing so as to communicate with the spool sliding holes. A land is formed on the outer peripheral side of the spool for connecting and disconnecting the oil passages.

JP 2008-002663 A

In the spool valve disclosed in Patent Document 1, in the neutral position, the actuator-side oil passage is blocked by the land of the spool from both the tank-side oil passage and the pump-side oil passage. . Therefore, in the neutral position, part of the land of the spool faces the oil passage on the tank side.

Here, in a fluid pressure control device that drives a plurality of actuators, a spool valve that controls working fluid that is supplied to and discharged from the actuators may be provided for each actuator. In this case, a tank that stores the working fluid discharged from each actuator is generally used in common. As such, the tank passageway that directs the hydraulic fluid discharged to the tank may be configured to pass through each of the spool valves included in the hydraulic control device. That is, the working fluid discharged from one actuator may pass through the tank passage of the spool valve that controls the operation of another actuator and be discharged to the tank.

Further, for example, the temperature of the working fluid discharged to the tank through the tank passage may rise due to the actuation of the actuator. Therefore, in the spool valve in the neutral position among the plurality of spool valves of the fluid pressure control device, the land provided on the spool is exposed to the flow of the working fluid with increased temperature discharged through the tank passage. As a result, the land of the spool thermally expands and is caught in the spool sliding hole, preventing the spool from sliding in the spool sliding hole, possibly causing malfunction of the spool valve.

SUMMARY OF THE INVENTION An object of the present invention is to improve the operational stability of a spool valve.

The present invention is a spool valve comprising: a spool movably inserted into a housing hole formed in a housing; a tank passage that opens into the housing hole and communicates with a tank that stores working fluid; a pump passage that guides the working fluid discharged from the pump; and an actuator passage that opens to the accommodation hole and guides the working fluid that is supplied to and discharged from the fluid pressure actuator. and an annular groove formed between adjacent land portions, and some of the land portions have a predetermined sliding clearance with respect to the receiving hole. and a facing portion at least partially facing the tank passage at a neutral position where communication of the actuator passage with the tank passage and the pump passage is cut off, respectively , and between the receiving hole and the facing portion. is larger than the sliding clearance between the receiving hole and the sliding portion and smaller than the clearance between the receiving hole and the annular groove.

In this invention, in the land portion facing the tank passage, the clearance of the facing portion facing the tank passage in the neutral position is larger than the sliding clearance of the sliding portion. That is, the facing portion exposed to the working fluid flowing through the tank passage in the neutral position has a relatively large clearance. Therefore, even if the temperature of the facing portion rises and expands due to the working fluid flowing through the tank passage, the spool is prevented from being caught on the inner periphery of the accommodation hole. As a result, the occurrence of malfunction in which the spool cannot slide with respect to the accommodation hole is suppressed.

Further, according to the present invention, the receiving hole opens to the end face of the housing, and the spool faces the tank passage. The sliding portion of the end land portion is provided closer to the end face side of the housing in the direction of movement of the spool than the facing portion of the end land portion, and extends from the housing hole to the outside through the opening of the housing hole. The length of the sliding portion of the end land portion in the direction of movement of the spool is set so that a part of the sliding portion of the end land portion always slides into the receiving hole regardless of the movement of the spool. characterized by

In this invention, even if the spool moves, the end land portion does not come into sliding contact with the receiving hole only by the facing portion, and even the sliding portion with relatively small sliding clearance makes sliding contact with the receiving hole. Leakage of hydraulic oil through the outer circumference of the land can be suppressed.

Moreover, the present invention is characterized in that the size of the clearance between the accommodation hole and the facing portion is set to less than 100 μm.
Further, the present invention is characterized in that the portion of the spool facing the tank passage in the neutral position is formed as a facing portion.

According to the present invention, the operational stability of the spool valve is improved.

FIG. 4 is a cross-sectional view of a spool valve according to an embodiment of the invention, showing the spool valve in a neutral position; FIG. 4 is an enlarged cross-sectional view showing the vicinity of the first land portion and the second land portion of the spool valve according to the embodiment of the present invention, showing a state in which the spool valve is in a neutral position; FIG. 3 is an enlarged cross-sectional view showing a first modification of the spool valve according to the embodiment of the present invention, and is a view corresponding to FIG. 2;

A spool valve 100 according to an embodiment of the present invention will be described below with reference to the accompanying drawings. The spool valve 100 switches supply and discharge of working fluid to and from the fluid pressure actuator to control the operation of the fluid pressure actuator. A spool valve 100 that controls the flow of working oil as working fluid supplied to and discharged from a hydraulic cylinder 1 as a fluid pressure actuator will be described below.

As shown in FIG. 1, the hydraulic cylinder 1 is a double-acting type having a piston 4 that divides the inside of the cylinder tube 2 into a rod-side chamber 5 as a first fluid pressure chamber and a bottom-side chamber 6 as a second fluid pressure chamber. is a cylinder. A piston rod 3 is connected to the piston 4 . A load (not shown) to be driven is connected to the tip of the piston rod 3 .

Hydraulic oil is supplied to and discharged from the rod-side chamber 5 of the hydraulic cylinder 1 through a first supply/discharge passage 7 . Hydraulic oil is supplied to and discharged from the bottom side chamber 6 of the hydraulic cylinder 1 through a second supply/discharge passage 8 .

Hydraulic cylinder 1 is extended by supplying hydraulic fluid to bottom side chamber 6 and discharging hydraulic fluid from rod side chamber 5 . Conversely, hydraulic oil is supplied to the rod-side chamber 5 and discharged from the bottom-side chamber 6, whereby the hydraulic cylinder 1 is contracted.

The spool valve 100 includes a housing 10, a spool 20 movably inserted into an accommodation hole 11 formed in the housing 10, first and second caps 30 and 40 attached to the housing 10, and the first cap 30. and a centering spring 50 as a biasing member provided inside and biasing the spool 20 in the axial direction.

The accommodation hole 11 is a through hole that opens to both side surfaces (end surfaces) 10A and 10B of the housing 10 . The accommodation hole 11 is a hole whose inner diameter is substantially constant along the axial direction. The first and second caps 30, 40 are attached to both side surfaces 10A, 10B of the housing 10 so as to seal the openings 11A, 11B of the receiving hole 11, respectively.

The housing 10 is formed with a rod-side passage 12 and a bottom-side passage 13 as actuator passages, a bridge passage 14 as a pump passage, and a pair of tank passages 15A and 15B, each of which opens into the housing hole 11 .

The rod-side passage 12 communicates with the rod-side chamber 5 of the hydraulic cylinder 1 and guides hydraulic fluid supplied to and discharged from the rod-side chamber 5 . The bottom-side passage 13 communicates with the bottom-side chamber 6 of the hydraulic cylinder 1 and guides hydraulic oil supplied to and discharged from the bottom-side chamber 6 .

The bridge passage 14 is formed so that both ends of the bridge passage 14 are open to the receiving holes 11 . Hydraulic oil discharged from the pump P is introduced to the bridge passage 14 through a pump port 16 . A load check valve 55 is provided between the pump port 16 and the bridge passage 14 to allow hydraulic oil to flow only from the pump port 16 toward the bridge passage 14 .

The tank passages 15A and 15B communicate with a tank T that stores hydraulic oil.

The spool 20 has a first land portion 21 , a second land portion 22 , a third land portion 23 , a fourth land portion 24 , and a fifth land portion 25 as a plurality of lands that slide with respect to the accommodation hole 11 . , the first annular groove 26A formed between the adjacent first land portion 21 and the second land portion 22, and the second land portion 26A formed between the adjacent second land portion 22 and the third land portion 23. A third annular groove 28A formed between the annular groove 27A and the adjacent third land portion 23 and fourth land portion 24 and between the adjacent fourth land portion 24 and fifth land portion 25 and a fourth annular groove 29A.

A first annular groove 26A, a second annular groove 27A, a third annular groove 28A, and a fourth annular groove 29A are formed on the outer peripheral surface of the spool 20, respectively. The plurality of annular grooves are for communicating the ports and passages opening in the accommodation hole 11 as the spool 20 moves. By forming the first annular groove 26A, the second annular groove 27A, the third annular groove 28A, and the fourth annular groove 29A, the first land portion 21 and the second land portion 22 are connected to the spool 20. A first connection portion 26 having an outer diameter smaller than that of the first land portion 21 and the second land portion 22 is connected to the second land portion 22 and the third land portion 23 to connect the second land portion 22 and the third land portion. A second connection portion 27 having an outer diameter smaller than that of the third land portion 23 and a third connection portion connecting the third land portion 23 and the fourth land portion 24 and having an outer diameter smaller than that of the third land portion 23 and the fourth land portion 24 . and a fourth connection portion 29 that connects the fourth land portion 24 and the fifth land portion 25 and has an outer diameter smaller than that of the fourth land portion 24 and the fifth land portion 25 . In the spool 20, the first land portion 21, the first connection portion 26 (the first annular groove 26A), the second land portion 22, the second connection portion 27 (the second annular groove 27A), the third land portion 23, the third One end side (Fig. 1) toward the other end side (right side in FIG. 1).

In this embodiment, the first annular groove 26A, the second annular groove 27A, the third annular groove 28A, and the fourth annular groove 29A have the same depth from the outer peripheral surface of the spool 20. As shown in FIG. In other words, the outer diameters of the first connecting portion 26, the second connecting portion 27, the third connecting portion 28, and the fourth connecting portion 29 are the same.

The first cap 30 has a first large diameter hole 31 into which the first land portion 21, which is one end of the spool 20, can enter, and communicates with the first large diameter hole 31 and has an inner diameter smaller than that of the first large diameter hole 31. A first small-diameter hole 32, a first pilot port 33 communicating with the first small-diameter hole 32, and an annular first step surface 34 provided between the first large-diameter hole 31 and the first small-diameter hole 32. have. A first pilot pressure chamber 35 is formed by the first large-diameter hole 31 and the first small-diameter hole 32 . A pilot pressure is introduced to the first pilot pressure chamber 35 through the first pilot port 33 .

The second cap 40 has a second large-diameter hole 41 into which the fifth land portion 25, which is the other end of the spool 20, can enter, and a second large-diameter hole 41 that communicates with the second large-diameter hole 41 and has an inner diameter larger than that of the second large-diameter hole 41. a small second small-diameter hole 42, a second pilot port 43 communicating with the second small-diameter hole 42, an annular second step surface 44 provided between the second large-diameter hole 41 and the second small-diameter hole 42, have A second pilot pressure chamber 45 is formed by the second large-diameter hole 41 and the second small-diameter hole 42 . A pilot pressure is introduced to the second pilot pressure chamber 45 through the second pilot port 43 .

As the spool 20 moves, the first land portion 21 of the spool 20 protrudes from the housing hole 11 through one opening 11A of the housing hole 11 and enters the first cap 30 . As the spool 20 moves, the fifth land portion 25 of the spool 20 protrudes from the accommodation hole 11 through the other opening 11B of the accommodation hole 11 with respect to the housing 10 and enters the second cap 40 .

A support member 60 that is coaxial with the spool 20 is provided on the first land portion 21 that is one end of the spool 20 . The support member 60 has a shaft portion 61 fixed to the first land portion 21 of the spool 20 and a head portion 62 having an outer diameter larger than that of the shaft portion 61 .

The centering spring 50 is provided on the outer periphery of the shaft portion 61 of the support member 60 between the end surface of the spool 20 (first land portion 21 ) and the head portion 62 of the support member 60 . Both ends of the centering spring 50 are connected to the end surface 10A of the housing 10 and the first cap 30 via spring seats 65 and 66, respectively, when the spool valve 100 is in a neutral position (state shown in FIG. 1), which will be described later. The user sits on the step surface 34 .

The spool valve 100 switches the communication state of the rod side passage 12 and the bottom side passage 13 with the tank passages 15A, 15B and the bridge passage 14 according to the position of the spool 20, and controls the supply and discharge of hydraulic oil to the hydraulic cylinder 1. .

Specifically, the spool valve 100 communicates the bridge passage 14 and the bottom side passage 13 with the neutral position (see FIG. 1) that blocks the supply and discharge of hydraulic oil to and from the hydraulic cylinder 1, and one of the tank passages 15A. and the rod side passage 12, and a retracted position in which the bridge passage 14 and the rod side passage 12 are communicated and the other tank passage 15B and the bottom side passage 13 are communicated.

When the pilot pressure is not introduced into both the first pilot pressure chamber 35 and the second pilot pressure chamber 45, the spool 20 is held in the neutral position by the biasing force of the centering spring 50 as shown in FIG. be. When the spool valve 100 is in the neutral position, the rod-side passage 12 and the bottom-side passage 13 are disconnected from the tank passages 15A and 15B and the bridge passage 14, respectively. More specifically, the rod-side passage 12 is blocked from communicating with the tank passage 15A by the second land portion 22 of the spool 20, and is blocked from communicating with the bridge passage 14 by the third land portion 23. The bottom side passage 13 is blocked from communication with the tank passage 15B by the fourth land portion 24 of the spool 20, and is blocked from communication with the bridge passage 14 by the third land portion 23.

As a result, the supply and discharge of hydraulic oil to and from the hydraulic cylinder 1 is cut off, and the hydraulic cylinder 1 enters a load holding state. At the neutral position, hydraulic fluid discharged from the pump P is led to the tank T through a neutral passage (not shown) formed in the housing 10 .

When the pilot pressure is introduced to the second pilot pressure chamber 45 , the spool 20 moves rightward in the drawing against the biasing force of the centering spring 50 . More specifically, the spool 20 moves rightward in the drawing until the head portion 62 contacts the bottom surface 32a of the first small-diameter hole 32 in the first cap 30 through which the first pilot port 33 opens. This switches the spool valve 100 to the extended position.

By switching the spool valve 100 to the extended position, the bottom side passage 13 communicates with the bridge passage 14 through the third annular groove 28A. Also, the rod-side passage 12 communicates with the tank passage 15A through the second annular groove 27A. As a result, hydraulic oil discharged from the pump P is guided to the bottom side chamber 6 through the bridge passage 14 , the third annular groove 28A, and the bottom side passage 13 . Hydraulic oil in the rod-side chamber 5 is discharged to the tank T through the rod-side passage 12, the second annular groove 27A, and the tank passage 15A. Therefore, the hydraulic cylinder 1 is extended.

When the pilot pressure is introduced to the first pilot pressure chamber 35 , the spool 20 moves leftward in the drawing against the biasing force of the centering spring 50 . More specifically, the spool 20 is rotated until the end portion (fifth land portion 25) of the spool 20 abuts against the bottom surface 42a of the second small-diameter hole 42 in which the second pilot port 43 opens in the second cap 40. , moves to the left in the figure. This switches the spool valve 100 to the retracted position.

By switching the spool valve 100 to the retracted position, the rod side passage 12 communicates with the bridge passage 14 through the second annular groove 27A. Also, the bottom-side passage 13 communicates with the other tank passage 15B through the third annular groove 28A. As a result, hydraulic fluid discharged from the pump P is guided to the rod side chamber 5 through the bridge passage 14 , the second annular groove 27</b>A, and the rod side passage 12 . Hydraulic oil in the bottom side chamber 6 is discharged to the tank T through the bottom side passage 13, the third annular groove 28A, and the tank passage 15B. Therefore, the hydraulic cylinder 1 is contracted.

It should be noted that the neutral path is blocked by the spool 20 in the extended and retracted positions. As a result, in the extended position and the retracted position, the hydraulic fluid discharged from the pump P is guided to the rod side chamber 5 or the bottom side chamber 6 through the bridge passage 14 without being guided to the tank T through the neutral passage.

Next, the configuration of the spool 20 will be described in detail with reference to FIGS. 1 and 2. FIG. In this embodiment, the first land portion 21, the second land portion 22, and the first annular groove 26A are provided facing one of the tank passages 15A in the neutral position. A fourth land portion 24, a fifth land portion 25, and a fourth annular groove 29A are provided facing the other tank passage 15B in the neutral position. In this way, the four lands, which are a part of the plurality of (five) lands formed on the spool 20, are configured to face the tank passages 15A and 15B in the neutral position. be.

In this embodiment, the first land portion 21 and the fifth land portion 25 have functions corresponding to each other so that their functions are switched according to the operating direction of the hydraulic cylinder 1 (the direction in which the spool valve 100 is switched). have. Similarly, the second land portion 22 and the fourth land portion 24 have functions corresponding to each other, and the second annular groove 27A and the fourth annular groove 29A have functions corresponding to each other. Therefore, in the following, the configurations related to the first land portion 21, the second land portion 22, and the first annular groove 26A will be mainly described, and the configurations related to the fifth land portion 25, the fourth land portion 24, and the fourth annular groove 29A will be mainly described. Description of the configuration is omitted as appropriate.

As shown in FIG. 2, the first land portion 21 includes a first large diameter portion 21A that slides with respect to the housing hole 11 with a predetermined sliding clearance (hereinafter referred to as "first clearance R1"); and a first small-diameter portion 21B that moves within the accommodation hole 11 with a clearance larger than that of the first large-diameter portion 21A (hereinafter referred to as “second clearance R2”). The first small-diameter portion 21B of the first land portion 21 has an outer diameter smaller than that of the first large-diameter portion 21A, and is provided so as to partially face the tank passage 15A in the neutral position. Since the first small-diameter portion 21B has an outer diameter smaller than that of the first large-diameter portion 21A, the first small-diameter portion 21B does not normally come into sliding contact with the inner peripheral surface of the receiving hole 11 . In the neutral position, the first large-diameter portion 21A does not face the tank passage 15A but faces the inner peripheral surface of the accommodation hole 11 .

Further, the clearance between the inner peripheral surface of the receiving hole 11 and the bottom of each annular groove (the outer peripheral surface of the connecting portion) is defined as a third clearance R3. The second clearance R2 is larger than the first clearance R1 and smaller than the third clearance R3 (R1>R2>R3).

Note that FIG. 2 shows the first clearance R1 and the second clearance R2 enlarged for convenience of explanation, and the ratio to the spool 20, the accommodation hole 11, the third clearance R3, etc. is not exact. For example, the first clearance R1 and the second clearance R2 are actually considerably smaller than the third clearance R3 of an annular groove such as the first annular groove 26A. As an example, the first clearance R1 has a size of about several μm, and the second clearance R2 is preferably larger than the first clearance R1 and set to less than 100 [μm]. In other words, the second clearance R2 does not positively communicate the ports or passages. If the clearance between the spool 20 and the housing hole 11 is 100 [μm] or more, the leakage flow rate of hydraulic oil through the clearance increases, which may cause the hydraulic cylinder 1 to malfunction. On the other hand, since the second clearance R2 is set to be less than 100 [μm], it is possible to reduce the flow rate of leakage of hydraulic oil through the second clearance R2 and reduce the risk of malfunction of the hydraulic cylinder 1. can.

The first large-diameter portion 21A of the first land portion 21 protrudes outside the accommodation hole 11 through the opening 11A of the accommodation hole 11 when moved from the neutral position to the extended position. In other words, the first large-diameter portion 21A is closer to the opening of the accommodation hole 11 through which the first large-diameter portion 21A passes than the first small-diameter portion 21B of the first land portion 21 in the moving direction (axial direction) of the spool 20. It is provided so as to be located on the side of the end face 10A where 11A is formed. Thus, the first land portion 21 corresponds to an “end land portion” that protrudes outside from the housing hole 11 through the opening 11A of the housing hole 11 . Further, the first large diameter portion 21A corresponds to the "sliding portion", and the first small diameter portion 21B corresponds to the "facing portion".

A portion of the first large diameter portion 21A is always in sliding contact with the inner peripheral surface of the accommodation hole 11 even when the spool valve 100 is in the extended position, in other words, regardless of the movement of the spool 20 . Specifically, the axial dimension L1 of the first large-diameter portion 21A that is in sliding contact with the receiving hole 11 in the neutral position is larger than the maximum stroke amount of the spool 20 when the spool valve 100 switches from the neutral position to the extended position. set to be large.

In addition, the dimension L1 of the first large diameter portion 21A that slides in contact with the receiving hole 11 in the neutral position means the first large diameter portion 21A and the first small diameter portion in the axial direction of the spool 20 when the spool valve 100 is in the neutral position. 21B to the end surface 10A of the housing 10 where the opening 11A of the accommodation hole 11 through which the first large diameter portion 21A passes is provided. Further, the maximum stroke amount of the spool 20 when the spool valve 100 is switched from the neutral position to the extended position is the head portion 62 of the support member 60 and the bottom surface 32a of the first small diameter hole 32 of the first cap 30 at the neutral position. corresponds to the dimension L3 (see FIG. 1) between That is, the dimension L1 of the first large diameter portion 21A is larger than the dimension L3 between the head portion 62 and the bottom surface 32a of the first small diameter hole 32 (L1>L3).

As a result, even when the spool valve 100 is switched to the extended position, the entire first large diameter portion 21A does not protrude from the housing hole 11, and only the first small diameter portion 21B of the first land portion 21 is extended to the housing hole 11. It is not in a state facing the inner peripheral surface of Since the second clearance R2 of the first small diameter portion 21B is relatively larger than the first clearance R1 of the first large diameter portion 21A (R2>R1), when compared with the first clearance R1 of the first large diameter portion 21A, Hydraulic oil is easily guided. When only the first small-diameter portion 21B of the first land portion 21 faces the inner peripheral surface of the housing hole 11, hydraulic fluid is likely to flow through the second clearance R2. On the other hand, even when the position is switched to the extended position, only the first small-diameter portion 21B faces the inner peripheral surface of the accommodation hole 11, and the first large-diameter portion 21A is configured to slide against the accommodation hole 11. , leakage of hydraulic oil between the first pilot pressure chamber 35 and the tank passage 15</b>A passing between the first land portion 21 and the accommodation hole 11 can be suppressed.

The second land portion 22 has a second large-diameter portion 22A that slides with a first clearance R1, which is a predetermined sliding clearance, with respect to the housing hole 11, and is larger than the first clearance R1 of the second large-diameter portion 22A. and a second small-diameter portion 22B that moves within the accommodation hole 11 with a large second clearance R2.

The first large diameter portion 21A of the first land portion 21 and the second large diameter portion 22A of the second land portion 22 have substantially the same outer diameter. Further, the first small diameter portion 21B of the first land portion 21 and the second small diameter portion 22B of the second land portion 22 are formed to have substantially the same outer diameter. The second small-diameter portion 22B of the second land portion 22 has an outer diameter smaller than that of the second large-diameter portion 22A, and is provided so as to partly face the tank passage 15A in the neutral position. The second large diameter portion 22A corresponds to the "sliding portion", and the second small diameter portion 22B corresponds to the "facing portion".

The second small diameter portion 22B of the second land portion 22 is provided so that a part thereof faces the tank passage 15A in the neutral position. The second large-diameter portion 22A does not face the tank passage 15A in the neutral position, and at least a portion of the second large-diameter portion 22A is located between the inner peripheral surface of the accommodation hole 11, more specifically, between the rod-side passage 12 and the tank passage 15A. slidably contact the inner peripheral surface of the accommodation hole 11 of the . That is, in the neutral position, communication between the rod side chamber 5 and the tank passage 15A through the clearance between the outer periphery of the spool 20 and the housing hole 11 is not limited to the second clearance R2 of the outer periphery of the second small diameter portion 22B. Configured. Specifically, the axial dimension L2 of the second small diameter portion 22B is within a range that allows leakage from the rod side passage 12 to the tank passage 15A through the clearance between the outer circumference of the spool 20 and the housing hole 11. , it is desirable to maximize the length.

Here, in general, in a fluid pressure control device that drives a plurality of actuators, a spool valve that controls working fluid that is supplied to and discharged from the actuators is provided for each actuator. In this case, it is common to use a common tank for storing the working fluid discharged from each fluid pressure actuator. As such, the tank passageway that directs the hydraulic fluid discharged to the tank may be configured to pass through each of the spool valves included in the hydraulic control device. In other words, working fluid discharged from one actuator may pass through the tank passage through the spool valve that controls the operation of another actuator and be discharged to the tank. Therefore, in the spool valve, even when the spool valve is in the neutral position, the working fluid guided to the tank passage may pass through the accommodation hole.

Further, for example, when the actuator is operated, or when the flow of hydraulic fluid that is led from the pump to the actuator through the spool valve is relieved to the tank by the relief valve, the temperature of the hydraulic fluid discharged to the tank through the tank passage rises. be. Therefore, in the spool valve in the neutral position among the plurality of spool valves of the fluid pressure control device, the land provided on the spool is exposed to the flow of the working fluid with increased temperature discharged through the tank passage. As a result, the land portion of the spool thermally expands and is caught in the accommodation hole, preventing the spool from sliding in the accommodation hole, which may cause malfunction of the spool valve.

In contrast, in the present embodiment, the first small diameter portion 21B of the first land portion 21 and the second small diameter portion 22B of the second land portion 22 face the tank passage 15A in the neutral position. The first small-diameter portion 21B and the second small-diameter portion 22B have a second clearance R2 larger than the first large-diameter portion 21A of the first land portion 21 and the second large-diameter portion 22A of the second land portion 22, respectively. Since it moves inside, it is less likely to get caught in the accommodation hole 11 even if it thermally expands. Therefore, the occurrence of malfunction of the spool valve 100 in which the spool 20 cannot slide in the accommodation hole 11 is suppressed. In other words, the second clearance R2 between the first small-diameter portion 21B and the second small-diameter portion 22B is set to a size that does not catch on the accommodation hole 11 even when thermally expanded.

Although detailed illustration and description are omitted, the fifth land portion 25 has, like the first land portion 21, a fifth large diameter portion as a sliding portion and a fifth small diameter portion as a facing portion. The fifth land portion 25 corresponds to an “end land portion” that protrudes to the outside of the accommodation hole 11 through the opening on the other side of the accommodation hole 11 .

Further, the fourth land portion 24 has a fourth large diameter portion as a sliding portion and a fourth small diameter portion as a facing portion, similarly to the second land portion 22 .

Therefore, the spool 20 is prevented from being caught in the accommodation hole 11 at the fourth land portion 24 and the fifth land portion 25 as well.

Further, as described above, even when the spool valve 100 is in the neutral position, the hydraulic fluid in the tank passages 15A and 15B may pass through the accommodation hole 11 and be guided. Therefore, by forming the first annular groove 26A and the fourth annular groove 29A facing the tank passages 15A and 15B in the neutral position in the spool 20, it is possible to ensure the flow path area of the hydraulic oil. As a result, the flow of hydraulic fluid passing through the accommodation hole 11 in the tank passages 15A and 15B is not hindered, and the hydraulic fluid can be guided smoothly.

According to the above embodiment, the following effects are obtained.

In this embodiment, in the neutral position, the first small diameter portion 21B of the first land portion 21 and the second small diameter portion 22B of the second land portion 22 face the tank passage 15A on one side, and the tank passage 15B faces the other tank passage 15B. faces the fourth small diameter portion of the fourth land portion 24 and the fifth small diameter portion of the fifth land portion 25 . The first small-diameter portion 21B, the second small-diameter portion 22B, the fourth small-diameter portion, and the fifth small-diameter portion are less likely to get caught in the accommodation hole 11 even when thermally expanded. Therefore, the occurrence of malfunction of the spool valve 100 in which the spool 20 cannot slide in the accommodation hole 11 is suppressed.

Further, in this embodiment, regardless of the movement of the spool 20, a part of the first large diameter portion 21A of the first land portion 21 is always in sliding contact with the inner peripheral surface of the accommodation hole 11, and the fifth land portion 25 is in contact with the inner peripheral surface of the housing hole 11. A portion of the large diameter portion 5 is always in sliding contact with the inner peripheral surface of the receiving hole 11 . As a result, even if the spool valve 100 is switched between the extended position and the retracted position, the entire first large diameter portion 21A or the entire fifth outer diameter portion slides in the accommodation hole 11 with the relatively small first clearance R1. does not protrude from the accommodation hole 11 to the outside. Therefore, the communication between the tank passage 15A and the first pilot pressure chamber 35 and the communication between the tank passage 15B and the second pilot pressure chamber 45 through the outer circumference of the spool 20 are achieved by the relatively small first clearance R1. 11 is interrupted by the first large diameter portion 21A and the fifth large diameter portion 21A. As a result, leakage of hydraulic oil through between the first land portion 21 and the accommodation hole 11 and between the fifth land portion 25 and the accommodation hole 11 can be suppressed.

Next, a modified example of this embodiment will be described.

<First modification>
In the above-described embodiment, the spool 20 has the first annular groove in order to secure the flow passage area for the flow of hydraulic oil in the tank passages 15A and 15B passing through the accommodation hole 11 when the spool valve 100 is in the neutral position. 26A and a fourth annular groove 29A are formed. Therefore, in the neutral position, in addition to the first annular groove 26A, the first land portion 21 and the second land portion 22 separated by the first annular groove 26A also face one of the tank passages 15A. Similarly, in the neutral position, in addition to the fourth annular groove 29A, the fourth land portion 24 and the fifth land portion 25 separated by the fourth annular groove 29A also face the other tank passage 15B. That is, in the above embodiment, two lands face each of the tank passages 15A and 15B in the neutral position. On the other hand, the first annular groove 26A or the fourth annular groove 29A is not an essential configuration, and may not be formed in the spool 20.

An example in which the first annular groove 26A is not formed will be described below. As shown in FIG. 3, in the first modification, when the spool valve 100 is in the neutral position, only one land portion (hereinafter referred to as "tank land portion 121") faces one tank passage 15A. be provided. The tank land portion 121 is partitioned into the spool 20 by forming a second annular groove 27A for communicating the rod side passage 12 with the tank passage 15A or the bridge passage 14 . The tank land portion 121 is an end land portion that protrudes to the outside of the accommodation hole 11 from one opening 11A of the accommodation hole 11 by switching to the extended position.

The tank land portion 121 has a pair of large diameter portions 121A and 121C as sliding portions and a small diameter portion 121B as a facing portion. The pair of large diameter portions 121A and 121C are provided at both ends of the small diameter portion 121B in the axial direction. The small diameter portion 121B is provided so as to axially cover the opening of the tank passage 15A with respect to the accommodation hole 11 in the neutral position. That is, in the neutral position, the opening of the tank passage 15A with respect to the accommodation hole 11 is provided so as to face the small diameter portion 121B as a whole.

The axial length L1 of the large-diameter portion 121A on the side of the end surface 10A of the housing 10 (the side opposite to the second annular groove 27A) from the small-diameter portion 121B is, like the first large-diameter portion 21A of the above embodiment, A portion of the large-diameter portion 121A is formed so as to be in sliding contact with the inner peripheral surface of the receiving hole 11 even in the extended position. That is, the dimension L1 along the axial direction of the large diameter portion 121A, more specifically, from the end surface 10A of the housing 10 when the spool valve 100 is in the neutral position to the boundary portion between the large diameter portion 121A and the small diameter portion 121B. is set to be larger than the maximum stroke amount L3 (see FIG. 1) of the spool 20 that switches from the neutral position to the extended position.

Even in this first modification, as in the above-described embodiment, the small diameter portion 121B of the tank land portion 121 faces the tank passage 15A in the neutral position, so the spool 20 is suppressed from being caught in the accommodation hole 11. .

Other modifications will be described below.

In the above embodiment, the inner diameter of the accommodation hole 11 is constant along the axial direction. Also, the first large diameter portion 21A and the first small diameter portion 21B of the first land portion 21, the second large diameter portion 22A and the second small diameter portion 22B of the second land portion 22, the fourth large diameter portion of the fourth land portion 24 The outer diameters of the portion and the fourth small-diameter portion, and the fifth large-diameter portion and the fifth small-diameter portion of the fifth land portion 25 are also constant along the axial direction, and the outer peripheral surfaces thereof are cylindrical surfaces. Therefore, the size of the first clearance R1 of each large diameter portion is constant, and the size of the second clearance R2 of each small diameter portion is constant. On the other hand, the second clearance R2 of the small diameter portion need not be constant in the axial direction as long as it is not smaller than the first clearance R1 of the large diameter portion.

For example, although not shown, the small-diameter portion may be formed to have a conical (tapered) outer peripheral surface whose outer diameter increases as it approaches the large-diameter portion in the axial direction. Even in this case, the same effect as that of the above embodiment can be obtained. Further, by adjusting the taper angle, the number of design parameters increases, making it easier to achieve both leakage of hydraulic oil through the second clearance R2 of the small diameter portion and prevention of catching due to thermal expansion.

In the above embodiment, the clearances of the first annular groove 26A, the second annular groove 27A, the third annular groove 28A, and the fourth annular groove 29A with respect to the accommodation hole 11 are the same as the third clearance R3. The first small diameter portion 21B of the first land portion 21, the second small diameter portion 22B of the second land portion 22, the fourth small diameter portion of the fourth land portion 24, and the fifth small diameter portion of the fifth land portion 25 are also accommodated. The clearance with respect to the hole 11 is the same at the second clearance R2. The second clearance R2 is smaller than the third clearance R3. On the other hand, when the third clearances R3 of the plurality of annular grooves with respect to the accommodation hole 11 are not the same, the second clearance R2 may be configured to be smaller than the smallest third clearance R3.

In the above embodiment, the first small diameter portion 21B of the first land portion 21 and the second small diameter portion 22B of the second land portion 22 partially face the tank passage 15A in the neutral position. The portion faces the inner peripheral surface of the receiving hole 11 where the tank passage 15A does not open. In order to prevent the spool 20 from being caught in the accommodation hole 11, it is desirable to secure a large axial dimension of the first small diameter portion 21B and the second small diameter portion 22B, but this is not the only option. At least in the neutral position, the first small-diameter portion 21B and the second small-diameter portion 22B are positioned in the axial range (inside the opening in the radial direction) where the tank passage 15A opens to the accommodation hole 11, It is sufficient that the opening of the tank passage 15A with respect to the accommodation hole 11 does not face the first large diameter portion 21A and the second large diameter portion 22A. The same applies to the second land portion 22, the fourth land portion 24, and the fifth land portion 25 as well.

Configurations, functions, and effects of embodiments of the present invention will be collectively described below.

The spool valve 100 includes a housing 10, a spool 20 movably inserted into a housing hole 11 formed in the housing 10, a tank passage 15A that opens into the housing hole 11 and communicates with a tank T that stores hydraulic oil. 15B, a bridge passage 14 that opens to the accommodation hole 11 and guides the hydraulic oil discharged from the pump P, and an actuator passage (rod side passage) that opens to the accommodation hole 11 and guides the hydraulic oil supplied to and discharged from the hydraulic cylinder 1 12, bottom side passage 13), and the spool 20 includes a plurality of land portions (first land portion 21, second land portion 22, third land portion 23, fourth land portion 23) that slide against the accommodation hole 11. land portion 24, fifth land portion 25), and annular grooves (first annular groove 26A, second annular groove 27A, third annular groove 28A, fourth annular groove 29A) formed between adjacent land portions; , and has a plurality of land portions (the land portions (second 1 land portion 21, a second land portion 22, a fourth land portion 24, and a fifth land portion 25). Sliding portions (first large diameter portion 21A, second large diameter portion 22A, fourth large diameter portion, fifth large diameter portion) that slide with a first clearance R1, and at least a portion of the tank passage in the neutral position facing portions 15A and 15B (a first small diameter portion 21B, a second small diameter portion 22B, a fourth small diameter portion, and a fifth small diameter portion), and a second clearance R2 between the housing hole 11 and the facing portions is larger than the first clearance R1 between the receiving hole 11 and the sliding portion and smaller than the third clearance R3 between the receiving hole 11 and the annular groove.

In this configuration, in the land portion facing the tank passages 15A and 15B, the second clearance R2 of the facing portion facing the tank passages 15A and 15B in the neutral position is larger than the first clearance R1 of the sliding portion. That is, the facing portion exposed to the hydraulic oil flowing through the tank passages 15A and 15B in the neutral position has a relatively large clearance. Therefore, even if the temperature of the facing portion rises and expands due to the hydraulic oil flowing through the tank passages 15A and 15B, the spool 20 is prevented from being caught on the inner circumference of the receiving hole 11. As shown in FIG. As a result, the occurrence of malfunction in which the spool 20 cannot slide with respect to the accommodation hole 11 is suppressed. Therefore, the operational stability of the spool valve 100 is improved.

Further, in the spool valve 100, the accommodation hole 11 opens to the end faces 10A and 10B of the housing 10, and the spool 20 serves as a land facing the tank passages 15A and 15B. 11, and has end land portions (first land portion 21, fifth land portion 25) that protrude outside from the housing hole 11 through the opening of the end land portion. Provided on the side of the end faces 10A, 10B of the housing 10 in the movement direction of the spool 20, protrudes from the accommodation hole 11 through the openings 11A, 11B of the accommodation hole 11, and slides of the end land parts in the movement direction of the spool 20. The length of is set so that a portion of the sliding portion of the end land always slides into the housing hole 11 regardless of the movement of the spool 20 .

With this configuration, even if the spool 20 moves, the end land portion does not face the inner peripheral surface of the accommodation hole 11 only by the facing portion, and the sliding portion with a relatively small sliding clearance faces the accommodation hole 11. Because of the sliding contact, hydraulic oil can be prevented from leaking through the outer periphery of the end land portion.

Further, in the spool valve 100, the size of the second clearance R2 between the accommodation hole 11 and the facing portion is set to less than 100 [μm].

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have.

DESCRIPTION OF SYMBOLS 100... Spool valve 1... Hydraulic cylinder (fluid pressure actuator) 10... Housing 10A, 10B... End surface 11... Accommodating hole 11A, 11B... Opening 12... Rod side passage (actuator passage) 13... Bottom side Passage (actuator passage) 14 Bridge passage (pump passage) 15A, 5B Tank passage 20 Spool 21 First land (end land) 21A First large diameter portion (sliding portion ), 21B... First small diameter portion (facing portion), 22... Second land portion, 22A... Second large diameter portion (sliding portion), 22B... Second small diameter portion (facing portion), 23... Third land portion , 24... fourth land portion 25... fifth land portion (end land portion) 26A... first annular groove 27A... second annular groove 28A... third annular groove 29A... fourth annular groove 121... Tank land portion (land portion, end land portion), 121A...large diameter portion (sliding portion), 121B...small diameter portion (facing portion), 121C...large diameter portion (sliding portion)

Claims (4)

a housing;
a spool movably inserted into an accommodation hole formed in the housing;
a tank passage that opens to the accommodation hole and communicates with a tank that stores the working fluid;
a pump passage that opens to the accommodation hole and guides the working fluid discharged from the pump;
an actuator passage that opens to the accommodation hole and guides working fluid supplied to and discharged from the fluid pressure actuator;
The spool has a plurality of lands that slide with respect to the accommodation holes, and an annular groove formed between the adjacent lands,
Some of the land portions among the plurality of land portions are
a sliding portion that slides with a predetermined sliding clearance with respect to the housing hole;
a facing portion at least partially facing the tank passage at a neutral position where communication of the actuator passage with the tank passage and the pump passage is cut off, respectively ;
The clearance between the accommodation hole and the facing portion is larger than the sliding clearance between the accommodation hole and the sliding portion and smaller than the clearance between the accommodation hole and the annular groove. A spool valve characterized by: A spool valve according to claim 1, wherein
The receiving hole opens to an end surface of the housing,
The spool has, as the land portion having the sliding portion and the facing portion, an end land portion that partially protrudes from the accommodation hole through the opening of the accommodation hole as the spool moves. ,
The sliding portion of the end land portion is provided closer to the end surface side of the housing in the moving direction of the spool than the facing portion of the end land portion, and the sliding portion is provided to slide from the housing hole through the opening of the housing hole. protrude outside,
The length of the sliding portion of the end land portion in the movement direction of the spool is such that a part of the sliding portion of the end land portion always slides into the accommodation hole regardless of the movement of the spool. A spool valve characterized in that it is set to A spool valve according to claim 1 or 2,
A spool valve, wherein a size of a clearance between the accommodation hole and the facing portion is set to be less than 100 μm. A spool valve according to any one of claims 1 to 3,
A spool valve, wherein a portion of the spool facing the tank passage in the neutral position is formed as the facing portion.

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