JPH04357306A - Counterbalance valve with relief function - Google Patents

Abstract

PURPOSE:To simplify a structure by composing a counterbalance valve of two divided spools so as to correspond a pair of supply/discharge passages, and moving the divided spools on the supply side of the passages so as to increase flow passage areas when the pressure in the passages gets a specified high value. CONSTITUTION:A counterbalance valve 9 arranged between a changeover valve 1 and a running actuator 12 of a crawler vehicle is prepared by fitting spools 25, 26 which are divided into two at each center in an axial direction into spool chambers 19, 19' linearly extending inside a main body 18. Blind holes 52, 53 having specified depths are formed on the inner ends of the divided spools 25, 26, into which holes rod bodies 54, 55 are fitted. Inner passages 68, 69 are formed on the divided spools 25, 26. When the actuator 12 shows pumping action and pressure on a discharge side of supply/discharge passages 15, 16 gets a specified value or higher, a moving means 70 heretofore composed moves the divided spools 25, 26 on the supply side of the passages 15, 16 so as to increase flow passage areas. This movement causes relief of high-pressure fluid.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterbalance valve with a relief function interposed between a pair of supply and discharge passages connecting a switching valve and a fluid actuator.

0002

[Prior Art] Conventionally, as a counterbalance valve,
For example, a device as described in Japanese Utility Model Application Publication No. 54-44390 is known, in which a counterbalance valve and a relief valve are provided in a casing separated from each other, and both valves are connected through a plurality of passages. connected.

0003

[Problems to be Solved by the Invention] However, in this type of device, a relief valve with a complicated structure is provided in addition to the counterbalance valve, and furthermore, these two valves are connected by a plurality of passages. Therefore, there are problems in that the overall structure becomes complicated and the manufacturing cost becomes high.

0004

OBJECTS OF THE INVENTION It is an object of the present invention to provide a counterbalance valve which has a relief function, has a simple overall structure, can be manufactured at low cost, and whose valve characteristics can be easily set.

[0005]

[Means for Solving the Problems] The present invention achieves the above object by configuring the spool of a counterbalance valve with two divided spools corresponding to each supply/discharge passage, and in which spools are formed in the axial direction within each divided spool. When the fluid actuator performs a pump action and the discharge side supply/discharge passage reaches a high pressure higher than a predetermined pressure, the supply side supply receives the high pressure. A moving means is provided for moving the divided spool of the discharge passage to a side where the flow passage area increases, and each of the rods is separated in the axial direction, and further, when the moving means is actuated, the passage is connected to the discharge side supply and discharge passage. This is achieved by a counterbalance valve with a relief function provided with a communication passage that communicates with the supply side supply and discharge passage and relieves the high pressure fluid in the discharge side supply and discharge passage to the supply side supply and discharge passage.

[0006]

[Operation] When the switching valve is switched to the flow position, high pressure fluid flows into the supply side supply and discharge passage, and the discharge side supply and discharge passage is connected to the low pressure side. At this time, the divided spool of the discharge side supply and discharge passage moves in response to the pressure in the supply side supply and discharge passage, and adjusts the flow area of the discharge side supply and discharge passage.

Next, when the fluid actuator begins to perform a pumping action, the pressure in the supply side supply and discharge passage decreases and the pressure in the discharge side supply and discharge passage increases. Then, when the pressure in the discharge side supply and discharge passage increases to a high pressure equal to or higher than a predetermined pressure, the moving means operates in response to the high pressure and moves the divided spool of the supply side supply and discharge passage to the side where the flow area increases. As a result, the discharge side supply and discharge passage and the supply side supply and discharge passage communicate with each other through the communication passage, whereby the high pressure fluid in the discharge side supply and discharge passage is relieved to the supply side supply and discharge passage through the communication passage. This prevents surge pressure from occurring in the circuit when the fluid actuator pumps. As described above, the counterbalance valve of the present invention has a simple structure and can perform both a counterbalance function and a relief function.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 to 3, a switching valve 1 and a fluid pump 2 are connected via a supply passage 3, and a switching valve 1 and a tank 4 are connected via a discharge passage 5.

The counterbalance valve 9 and the switching valve 1 are connected via a pair of first supply/discharge passages 10 and 11, and the counterbalance valve 9 and a fluid actuator 12 for driving the crawler vehicle are connected to a pair of second supply/discharge passages 10 and 11. They are connected via drainage channels 13 and 14.

[0010] The first and second supply/discharge passages 10, 13 and the first,
The second supply and discharge passages 11 and 14 as a whole are a pair of supply and discharge passages 15 and 1 that connect the switching valve 1 and the fluid actuator 12.
6, and the counterbalance valve 9 is interposed in the middle of these supply and discharge passages 15 and 16.

The counterbalance valve 9 has a block-shaped main body 18, and a spool chamber 19 extending linearly and having a circular cross section is formed within the main body 18. Caps 20 are provided at both longitudinal ends of the spool chamber 19 of the main body 18, respectively.
21 is screwed and fixed, and both ends of the spool chamber 19 are closed by caps 20 and 21. main body 18,
The caps 20 and 21 as a whole have a spool chamber 1 inside.
9 is formed in the casing 22. A spool 24 is slidably housed in the spool chamber 19 in a sealed manner, and the spool 24 is composed of two divided spools 25 and 26 that are divided into two at the center in the axial direction so as to correspond to the supply and discharge passages 15 and 16. has been done.

Steps 29 and 30 are formed in the main body 18, and the outer ends of the divided spools 25 and 26 in the axial direction (divided spool 25
There are steps 29 and 30 on the left end of the split spool 25 and the right end of the split spool 25.
Flanges 27 and 28 are formed that can be brought into contact with. When the split spools 25 and 26 move axially inward and the flanges 27 and 28 come into contact with the steps 29 and 30, the split spools 25 and 26 are restricted from moving inward in the axial direction and reach the inner end position A. (See Figure 1). The split spools 25 and 26 can each be moved axially outward from this inner end position A. In addition, the split spool 25,
26 is stopped at the inner end position A, a small gap 33 is formed between the inner end surfaces 31 and 32 facing each other.

A pair of first passages 35 and 36 are formed in the main body 18, one end of which is connected to the first supply and discharge passages 10 and 11, respectively, and the other end thereof opens into the spool chamber 19. Main body 1
A pair of second passages 37 and 38 are formed in 8, one end of which is connected to the second supply and discharge passages 13 and 14, respectively, and the other end connected to the first
It opens into the spool chamber 19 at a position axially inner than the passages 35 and 36.

When the split spools 25 and 26 are respectively located at the inner end position A (FIG. 1), there is communication between the first passage 35 and the second passage 37 and between the first passage 36 and the second passage. 38 is cut off by the split spools 25 and 26, and when the split spools 25 and 26 respectively move axially outward from the inner end position A (FIG. 3), the communication between the first passage 35 and the first passage 38 is interrupted by the split spools 25 and 26. The two passages 37 and the first passage 36 and the second passage 38 communicate with each other.

Check valve 39 in counter balance valve 9
, 40 are built in, the check valve 39 is interposed between the first passage 35 and the second passage 37, and the check valve 40 is interposed between the first passage 36 and the second passage 38. The check valve 39 only allows fluid to flow from the first supply/discharge passage 10 to the second supply/discharge passage 13, and the check valve 40 allows fluid to flow from the first supply/discharge passage 11 to the second supply/discharge passage 14. Allow only flow.

The selection passage 43 is connected at one end to the first supply/discharge passage 10 and at the other end to the first supply/discharge passage 11, and in the middle of the selection passage 43 is a shuttle that allows flow only toward the center of the selection passage 43. A valve 44 is interposed. In addition, shuttle valve 4
4 is connected to an intermediate passage 46. selection passage 43,
The shuttle valve 44 and the intermediate passage 46 collectively constitute a high pressure selection mechanism 47 that selects and takes out high pressure fluid from the supply and discharge passages 15 and 16 on the supply side.

A high pressure passage 48 is formed in the casing 22, one end of the high pressure passage 48 is connected to the intermediate passage 46, and the other end opens at the center of the spool chamber 19 in the axial direction. High pressure fluid is in high pressure passage 48
Through the spool chamber 19 between the divided spools 25 and 26 (
The fluid is guided into the gap 33) and acts on the inner end surfaces 31, 32 of the split spools 25, 26 to apply a fluid force directed outward in the axial direction to the split spools 25, 26.

Inner end surfaces 31, 3 of split spools 25, 26
Blind holes 52 and 53 of a predetermined depth are formed coaxially with the split spools 25 and 26, respectively.
, second rod bodies 54 and 55 are each slidably inserted in a sealed manner. The first and second rod bodies 54 and 55 are divided into two rod pieces 54a and 5 divided in the axial direction, respectively.
It consists of 4b, 55a, and 55b. In the illustrated embodiment, the main body portions of the small rod pieces 54a to 55b have the same diameter, and the small rod piece 54 located at the innermost part of the holes 52 and 53
The tips 54c and 55c on the rear side of b and 55b have a smaller diameter than the main body portion.

Divided spools 25 and 26 in the spool chamber 19
A spring chamber 6 is provided between the outer end surface of the cap 20 and the cap 20, 21.
The spring chambers 61, 62 and the first passages 35, 36 are always in communication via transmission passages 63, 64 formed in the split spools 25, 26. The fluid inside is guided to the outer end surfaces of the split spools 25 and 26 through transmission passages 63 and 64, respectively. Return springs 65 and 66 are housed in the spring chambers 61 and 62, respectively, and urge the divided spools 25 and 26 toward the inner end position A, respectively. Internal passages 68 and 69 are formed in the split spools 25 and 26, respectively, and one end communicates with the second passages 37 and 38, respectively, and the other end communicates with the deepest parts of the holes 52 and 53, respectively, and the supply/discharge passage 15 , 16 from check valves 39, 40 through internal passages 68, 69 to holes 52,
53 respectively, and the first and second rod bodies 5
4, 55.

A communication passage 72 is formed in the casing 22 , and the left end of the communication passage 72 opens into the spool chamber 19 axially inside the second passage 37 , and the right end opens into the spool chamber 19 axially inside the second passage 38 . There are 25 split spools,
When the split spool 25 is located at the inner end position A (FIGS. 1 and 2), the left end of the communication passage 72 cooperates with the annular recesses 25a and 26a formed on the circumferential surface of the spool 26. 37, and communicates with the second passage 37 when the split spool 25 moves axially outward from the inner end position A (FIG. 3). Similarly, the right end of the communication passage 72 is connected to the split spool 2.
When the split spool 26 is located at the inner end position A (FIG. 1), it is blocked from the second passage 38, and when the split spool 26 moves axially outward from the inner end position A (FIGS. 2 and 3). communicates with the second passage 38. In this way both split spools 25
, 26 move axially outward from the inner end position A, the supply/discharge passages 15 and 16 communicate with each other through the communication passage 72. The recesses 25a, 26a of the split spools 25, 26 and the axially intermediate portions of the holes 52, 53 form internal passages 68a, 69.
The pressure in the recesses 25a, 26a is transmitted to the intermediate portions of the holes 52, 53.

The holes 52, 53, the rod bodies 54, 55, and the internal passages 68, 69 collectively form the fluid actuator 12.
When the supply and discharge passages 15 and 16 on the discharge side become high pressure higher than a predetermined pressure due to the pump action, the divided spools 25 and 26 of the supply and discharge passages 15 and 16 on the supply side are reduced in flow path area by receiving the high pressure. It constitutes a moving means 70 that moves it to the side where the amount increases, that is, to the outside in the axial direction.

Next, the operation of this embodiment will be explained. When the switching valve 1 is in the neutral position C, each part of the counterbalance valve 9 is in the state shown in FIG. The switching valve 1 is switched from this neutral position C to a flow position, for example, a parallel flow position D, and allows the high pressure fluid discharged from the fluid pump 2 to flow into the supply and discharge passage 15 on the supply side, and also causes the high pressure fluid discharged from the fluid pump 2 to flow into the supply and discharge passage 15 on the discharge side.
6 is connected to the tank 4 (Fig. 2), the high-pressure fluid that has flowed into the supply/discharge passage 15 passes through the check valve 39 of the counterbalance valve 9, flows into the fluid actuator 12, rotates the fluid actuator 12, and then the low-pressure fluid and is discharged into the supply/discharge passage 16.

At this time, the high-pressure fluid flowing into the supply/discharge passage 15 is selected by a high-pressure selection mechanism 47 consisting of a selection passage 43, a shuttle valve 44, and an intermediate passage 46, and is passed through the high-pressure passage 48.
It flows into the small gap 33 between the split spools 25, 26, and the inner end surfaces 31, 32 of both the split spools 25, 26.
It acts on Further, the high pressure fluid in the supply/discharge passage 15 passes through the transmission passage 63 to the spool chamber 61 of the divided spool 25.
It is also guided to the left outer end face facing the. Therefore, the fluid forces acting on both end surfaces of the divided spool 25 are balanced, and the divided spool 25 of the supply side supply/discharge passage 15 continues to stop at the inner end position A.

On the other hand, the spool chamber 62 of the divided spool 26
Since the low-pressure fluid in the supply and discharge passage 16 is guided from the transmission passage 64 to the right outer end face facing the side, a difference occurs in the fluid force acting on both end faces of the split spool 26, and as a result, the discharge side supply and discharge passage 16 Only the divided spool 26 is connected to the supply side supply/discharge passage 15.
In response to internal pressure, the spring 66 is compressed and moved axially outward (rightward) to adjust the flow area of the supply/discharge passage 16.

As the divided spool 26 moves to the right, the flow area of the supply/discharge passage 16 increases, so the low pressure fluid flowing out from the fluid actuator 12 is discharged into the tank 4 through the supply/discharge passage 16 and the discharge side passage 5. . In this way, the fluid actuator 12 rotates at a predetermined speed and the crawler vehicle moves forward. At this time, the supply/discharge passage 15 is connected to the outer end surface (left end surface) of the first rod body 54 through the internal passage 68.
Since the high-pressure fluid inside is guided, the first and second rod bodies 54 and 55 are united by the fluid force of the high-pressure fluid until the tip of the small rod piece 55b abuts the innermost part of the hole 53 of the split spool 26. It is moved to the right (Figure 2).

Next, when the crawler vehicle starts traveling downhill, the fluid actuator 12 acts as a pump, that is, sucks fluid from the supply side supply and discharge passage 15 and discharges the fluid to the discharge side supply and discharge passage 16. Then, the pressure in the supply/discharge passage 15 and the high pressure passage 48 decreases, and the pressure within the supply/discharge passage 16, that is, the second supply/discharge passage 14 increases. As a result, the discharge-side divided spool 26 is urged by the return spring 66 and moves leftward toward the inner end position A. When the divided spool 26 moves in this way, the opening area of the supply/discharge passage 16 increases. The pressure gradually decreases and the pressure inside the second supply/discharge path 14 increases. This increased pressure in the second supply/discharge path 14 acts on the fluid actuator 12 as a back pressure, and applies a braking force to the fluid actuator 12. At this time, the fluid whose pressure has increased in the supply/discharge passage 16 is guided to the outer end surface 55c of the right rod small piece 55b of the second rod body 55 through the internal passage 69, so that the rods 54 and 55 are moves toward the left until it abuts the innermost part of the hole 52 of the split spool 25. When the leftward movement of the split spool 26 significantly reduces the opening area of the supply/discharge passage 16 and the pressure within the second supply/discharge passage 14 rises to a high pressure higher than a predetermined pressure, the rod 55 within the split spool 26 The acting fluid force exceeds the biasing force of the return spring 65. At this time, the moving means 70 operates in response to the high pressure, and the rods 54 and 55 move the divided spool 25 of the supply side supply/discharge passage 15 axially outward (leftward), that is, the flow path area increases. move it to the side. On the other hand, since the split spool 26 of the discharge side supply/discharge passage 16 is still moving toward the inner end position A, both the split spools 25 and 26 are displaced axially outward from the inner end position A. As a result, both ends of the communication passage 72 are connected to the second passage 3.
7 and 38, respectively (see FIG. 3).

As a result, the supply and discharge passage 16 on the discharge side and the supply and discharge passage 15 on the supply side communicate with each other through the communication passage 72, and the fluid in the supply and discharge passage 16, which has a high pressure higher than a predetermined pressure, is released through the communication passage 72. It is relieved in the supply/discharge passage 15, and the situation in which surge pressure is generated in the circuit is prevented. In this way, the counterbalance valve 9 of this embodiment can perform both the counterbalance function and the relief function although it has a simple structure.

Note that the split spool 2 on the brake pressure generation side
6 returns from the stroke end (right end) to the neutral position A, the high pressure fluid generated in the supply/discharge passage 16 passes through the internal passages 69, 69a at the initial stage and acts on both rod pieces 55a, 55b of the rod body 55, causing the rod Small piece 55a
, 55b to the opposite divided spool side. On the other hand, when the divided spool 26 returns to near the neutral position, the internal passage 69a is closed by the land portion 71 of the divided spool 26, and due to this closure, it is no longer relieved. However, the internal passage 69 always transmits the pressure oil generated at this port to the small rod piece 55b on the back side.

As described above, the rod 55 is composed of a plurality of small rod pieces 55a, 55b, and each small rod piece 55a, 5
By transmitting the pressure of the supply/discharge passage 16 to 5b according to the position of the split spool 26, low pressure relief can be provided when the brake is applied, and the crawler vehicle can be stopped without shock. In particular, rod pieces 54a and 54
b. When the small rod pieces 55a and 55b have the same diameter,
It has actually been confirmed that the shock is reduced when a crawler vehicle is suddenly switched between forward and backward motion. Further, after stopping, the land 71 sets a high relief pressure to improve the performance of maintaining the stopped state, that is, the performance of the parking brake.

Further, among the small rod pieces, small rod pieces 54a and 55 located on the inner end surfaces 31 and 32 side of the holes 52 and 53
By making b larger in diameter than the other small rod pieces 54b and 55b, the relief pressure at the time of stopping can be lowered. Conversely, the rod small piece 5 is smaller than the rod small pieces 54a and 55a.
By making 4b and 55b large in diameter, the relief pressure after stopping can be increased and the parking brake performance can be improved.

Note that the switching valve 1 is moved from the flow position to the neutral position C.
Even when the switch is switched to , the counterbalance valve 9 operates in the same manner as described above. In addition, in the above explanation, the switching valve 1 was switched from the neutral position C to the parallel flow position D, and the supply/discharge passage 15 was set as the supply side and the supply/discharge passage 16 was set as the discharge side. The counterbalance valve 9 also operates in the same manner as described above when switching to the oblique flow position E and setting the supply/discharge passage 16 on the supply side and the supply/discharge passage 15 on the discharge side.

[0032]

According to the present invention, despite having a relief function, the overall structure is simple and can be manufactured at low cost, and the valve characteristics can be easily set.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a neutral state of an embodiment of the present invention.

FIG. 2 is a sectional view showing the state of the actuator of the above embodiment when it is rotating.

FIG. 3 is a sectional view showing the state of the above embodiment during braking.

[Explanation of symbols]

1 Switching valve 9 Counterbalance valve 12 Fluid actuator 15 Supply/discharge passage 16 Supply/discharge passage 24 Spool 25 Split spool 26 Split spool 54 Rod body 55 Rod body 54a Rod small piece 54b Rod small piece 55a Rod small piece 55b Rod small piece 70 Means of transportation 72 Communication passage

Claims (1)

[Claims] [Claim 1] It is interposed in the middle of a pair of supply and discharge passages connecting the switching valve and the fluid actuator, and adjusts the flow area of the discharge side supply and discharge passage in response to the pressure in the supply side supply and discharge passage. In this counterbalance valve, the spool of the counterbalance valve is composed of two split spools corresponding to each supply/discharge passage, and a hole is formed in the axial direction in each split spool, and a slider is inserted into each of the holes. It consists of a movably inserted rod, and when the fluid actuator performs a pump action and the discharge side supply/discharge passage reaches a high pressure higher than a predetermined pressure, the divided spool of the supply side supply/discharge passage receives the high pressure and moves the divided spool of the supply side supply/discharge passage into the flow path. A moving means for moving the rods to the side where the area increases is provided, each of the rods is separated in the axial direction, and further, when the moving means is operated, the discharge side supply and discharge passage and the supply side supply and discharge passage are communicated. A counterbalance valve with a relief function, characterized in that a communication passage is provided for relieving high pressure fluid in a discharge side supply and discharge passage to a supply side supply and discharge passage.