JP3344283B2 - Counter balance valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterbalance valve for controlling the operation speed of an actuator,
The present invention relates to a device suitable for use in controlling a traveling motor of a construction machine.

[0002]

2. Description of the Related Art When a construction machine or the like travels downhill, a counterbalance valve of this type is provided with a supply / discharge passage connected to a tank and an actuator in accordance with a decrease in pressure of a supply / discharge passage connected to a pump. By narrowing the space between the building and the passage, the construction machine or the like is prevented from running on its own. As such a conventional counterbalance valve, there is Japanese Utility Model 2-21659.
There is one described in Japanese Patent Publication No. Referring to FIG. 5, when the construction machine is stopped, when the main valve 4 provided between the counter balance valve 1 and the pump 2 and the tank 3 is switched to a neutral position, The spool 5 of the balance valve 1 also moves to the neutral position for a short time to shut off the connection between the supply / discharge passage (the discharge-side passage at that time) and the actuator passage. At this time, since the inertia force is acting on the construction machine and the like, the traveling motor 6 tries to keep rotating by the inertia force.
The traveling motor 6 sends out the hydraulic oil in the same manner as the pump, and it is necessary to suck in an amount corresponding to the sent out hydraulic oil. In this case, the sucked hydraulic oil is sucked by opening one of the check valves 7a and 7b of the counterbalance valve 1 according to the rotation direction of the traveling motor 6, but has the following problem.

That is, when one of the check valves 7a and 7b (in this case, 7a) is opened to suck the operating oil, the valve body 8a of the check valve 7a is connected to the outlet passage 9 of the check valve 7a.
a of the opening to the valve chamber 10a, the inner edge opposite to the valve seat 11a;
After that, the hydraulic oil in the portion opposite to the valve seat 11a of the valve chamber 10a, which is roughly divided by the head of the valve body 8a, is sealed, and the pressure in the sealed portion is reduced. Since the pressure is higher than the pressure on the valve seat 11a side, the valve element 8a cannot move beyond the inner edge of the opening of the outlet passage 9a to the valve chamber 10a on the opposite side to the valve seat 11a. Therefore, a sufficient passage area cannot be ensured, and a pressure loss occurs due to the check valve 7a. As a result, cavitation occurs between the check valve 7a and the travel motor 6, which adversely affects the travel motor (actuator) 6. There is a problem. In order to prevent this, it is conceivable to increase the passage area of the outlet passages 9a and 9b formed in the spool 5, but if the passage area is increased, the strength of the spool 5 is reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent cavitation when a construction machine or the like is stopped.

[0005]

According to the present invention, there is provided a main body having a spool hole, a spool slidably inserted into the spool hole, and a power supply formed in the main body and connected to a pump or a tank. An actuator passage connected to a discharge passage and an actuator; and a check valve provided in the spool and having a forward direction from the supply / discharge passage toward the actuator passage, wherein the check valve is provided inside the spool. A valve chamber, an inlet passage communicating the valve chamber with the supply / discharge passage, a valve seat formed at an opening of the inlet passage to the valve chamber, and seatable on the valve seat. In a counterbalance valve having a valve body and an outlet passage communicating between the valve chamber and the actuator passage and having an opening facing a side surface of the valve body, the valve seat having an opening to the valve chamber of the outlet passage is Characterized in that in contralateral provided communication means for communicating with said valve chamber and said actuator passage (claim 1).

In this means, since the communicating means for connecting the actuator passage and the valve chamber is formed on the opposite side of the valve seat of the opening of the outlet passage to the valve chamber, the valve element is opened to the valve chamber of the outlet passage. Even when the valve body moves to the lower side, the valve body can move beyond the opening of the outlet passage because the pressure on the side opposite to the valve seat is low due to the communication means, and the opening amount of the check valve, that is, the passage area becomes large. The pressure loss is reduced, and the occurrence of cavitation at the time of sucking the hydraulic oil can be prevented.

In the above means, it is preferable that the communication means is a notch extending from an opening edge of the outlet passage to the valve chamber toward a side opposite to the valve seat. ). In this configuration, the communication means is formed as a notch extending from the edge of the opening of the outlet passage to the valve chamber toward the end opposite to the valve seat. Can be increased.

[0008] In the above means, it is preferable that the notch is a groove formed in the valve chamber (claim 3). In this configuration, since the notch is a groove formed on the inner surface of the valve chamber, a decrease in the strength of the spool can be suppressed.

In the above means, it is preferable that the communication means is a through hole provided on an opposite side of the opening of the outlet passage to the valve chamber from the valve seat.
In this configuration, since the communicating means is a through hole provided on the side opposite to the valve seat of the opening to the valve chamber of the outlet passage, the communicating means can be provided by easy processing, and the valve opening amount of the valve body can be reduced. Can be bigger.

[0010] In the above means, it is preferable that the opening area of the through hole is smaller than the opening area of the outlet passage to the valve chamber. In this configuration, since the opening area of the through hole is made smaller than the opening area of the outlet passage to the valve chamber, a decrease in the strength of the spool can be suppressed.

In the above means, it is preferable that the communication means is a passage provided on an outer peripheral side of a portion of the valve body which is seated on the valve seat (claim 6). In this configuration, by forming the communicating means on the outer peripheral portion of the valve body, the valve opening amount can be increased without changing the structure of the spool, and the strength of the spool does not decrease.

In the above means, the valve body has an enlarged head on which a seat portion for sitting on the valve seat is formed, and the outer diameter of the enlarged head on the side opposite to the seat portion is enlarged. It is preferable to adopt a configuration in which the diameter is smaller than the maximum outer diameter. In this configuration, the opposite side to the seating portion of the enlarged head of the valve body is smaller in diameter than the maximum diameter of the enlarged head, so the valve body moves until the small diameter portion overlaps beyond the opening of the outlet passage. It is possible to further increase the opening amount of the check valve.

[0013]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. The counterbalance valve 20 includes a main body 21, a spool 22, and check valves 23 and 24 provided in the spool, and is applied to a hydraulic circuit of an actuator 31 for traveling of a construction machine.

The main body 21 has a spool hole 25 in which supply / discharge passages 29 and 30 connected to a pump 26 or a tank 27 and an actuator 31 are provided.
Are formed so that the spool hole 25 is partially enlarged.

The spool 22 is slidably inserted into the spool hole 25. Pressure chambers 34 and 35 also serving as spring chambers are provided at both ends of the spool 22 to accommodate coil springs 36 and 37 and supply / discharge passages 29 and
Branch passages 38 and 39 branching off from 30 are connected to each other via the districts 40 and 41. Coil spring 3
6 and 37 hold the spool 22 at the neutral position in a state where pressure is not supplied to any of the pressure chambers 34 and 35, and when pressure oil is supplied to one of them, the spool 22 overcomes the spring force and
2 to move the actuator passage 32 and the supply / discharge passage 2
9 or the communication between the actuator passage 33 and the supply / discharge passage 30.

The spool 22 has a similar check valve 2 inside.
3 and 24 are provided. To explain one of them,
The check valve 23 is connected between the supply / discharge passage 29 and the actuator passage 3.
2, a valve chamber 42, an inlet passage 43 which communicates the valve chamber 42 with the supply / discharge passage 29, and is provided so as to close the valve with a valve closing spring having a small acting force. A valve seat 44 formed at the opening of the valve 43 to the valve chamber 42;
It has a valve body 45 provided in the valve chamber 42 so as to be able to be seated on the valve seat 44, and an outlet passage 46 communicating the inside of the valve chamber 42 with the actuator passage 32 and having an opening facing the side surface of the valve body 45. The valve body 45 is a poppet valve having an enlarged head 70 at one end of a small diameter portion 68. The other check valve 24 is also in the supply / discharge passage 3
0 and the actuator passage 33,
It has a valve chamber 47, an inlet passage 48, a valve seat 49, a valve body 50, and an outlet passage 51, and the valve body 50 has a small diameter portion 69 and an enlarged head 71.

The outlet passages 4 of the check valves 23, 24
Communication means 52, 53 are provided in connection with 6, 51. As shown in FIGS. 1A and 1B, the communication means 52 connects the actuator passage 32 and the valve chamber 42 on the side opposite to the valve seat 44 of the opening of the outlet passage 46 to the valve chamber 42. Is a notch 54 provided in the first position. That is, the outlet passage 46 is a circular hole in the radial direction of the spool, and the notch 54 is on the opposite side to the valve seat 44 from the edge of the circular hole, that is, the valve body 4.
5 extends in the retreating direction when opened. Similarly, the communication means 53 is connected to the actuator passage 33 on the opposite side of the valve seat 49 of the opening of the outlet passage 51 to the valve chamber 47.
And a notch 55 provided so as to communicate the valve chamber 47 with the valve chamber 47.

The other details are substantially the same as those of the conventional counterbalance valve and have little relation to the main part of the present invention, so that the description is omitted. In use, as shown in FIG. 1A, a main valve (direction switching valve) for controlling rotation and stop of the actuator 31 and a rotation direction is provided between the supply / discharge passages 29 and 30 and the pump 26 and the tank 27. )
56 and a relief valve 57 are provided.

In the counterbalance valve configured as described above, the main valve 56 is switched from, for example, the neutral position to the right in the drawing, and the pump 26 is connected to the supply / discharge passage 30 and the tank 27 is connected to the supply / discharge circuit 29. When the connection is established, the pressure oil supplied to the supply / discharge passage 30 pushes and opens the check valve 24 and the actuator passage 3
3 and is supplied to the actuator 31. At this time, since the pressure oil is also supplied to the pressure chamber 35 via the check valve of the restrictor 41 in the branch passage 39, the spool 22 moves to the right in the drawing, and the spool 22 moves to the right in FIG. Are connected by an annular recess of the spool. Accordingly, the actuator 31 rotates in a predetermined direction, for example, in a direction in which the construction machine moves forward.

To stop the actuator 31 while it is rotating in the forward direction, the main valve 56 is operated to the neutral position. Thereby, the supply / discharge circuit 30 and the pressure chamber 35
Of the counter balance valve 20
2 also moves to the neutral position. At this time, since the inertia force is acting on the construction machine, the actuator 31 tries to keep rotating. The rotation of the actuator 31 sucks the hydraulic oil from the actuator passage 33 and discharges it to the actuator passage 32. The spool 22 causes the hydraulic oil in the pressure chamber 35 to be supplied to the restrictor 41 by the return action of the coil spring 36.
And then gradually return to the neutral position,
The distance between the actuator passage 32 and the supply / discharge circuit 29 is gradually reduced and cut off. That is, the impact at the time of stopping is reduced. While the spool 22 returns to the neutral position, the check valve 2
The valve 4 is largely opened by suction of the actuator 31. That is, when the valve body 50 moves in the valve opening direction, even if the back surface of the enlarged head 71 reaches near the edge of the circular hole of the outlet passage 51 on the side opposite to the valve seat 49, the notch of the communication means 53 is notched. 5
Because of the presence of 5, the hydraulic oil is not confined in the valve chamber 47 on the back side of the enlarged head 71, and moves further in the valve opening direction to fully open the valve. As a result, the working oil sufficiently flows into the actuator passage 33 side, so that the pressure loss is small and the occurrence of cavitation is prevented. Also,
When the spool 22 returns to the neutral position from the opposite direction,
Check valve 23 operates in a similar manner to prevent cavitation.

FIG. 2 shows a second embodiment of the present invention.
The difference from the first embodiment is that the communication means 52, 53
Are grooves 58 and 59 formed in the valve chambers 42 and 47 with respect to the outlet passages 46 and 51. That is, the groove 58 will be described.
In the valve chamber 42, it extends from the edge opposite to the side 4 in the direction opposite to the valve seat 44, that is, in the direction in which the valve body 45 retracts when it opens. The groove 59 also extends in the valve chamber 47 toward the side opposite to the valve seat 49. The other points are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and the description thereof is omitted.

In this embodiment, when the actuator passage 33 is sucked when the spool 22 returns to the neutral position, the valve body 50 of the check valve 24 moves in the valve opening direction, and the rear surface of the enlarged head 71 is closed. Even when reaching the vicinity of the edge of the circular hole of the outlet passage 51 on the side opposite to the valve seat 49, the hydraulic oil is not sealed in the valve chamber 47 on the back side of the enlarged head 71 because the groove 59 exists. Further, the valve body 50 moves in the valve opening direction to fully open the valve. This prevents cavitation as in the first embodiment. Also, the spool 22
Also returns to the neutral position from the opposite direction, the check valve 23 operates in the same manner to prevent cavitation. In addition, the beveled slopes 66 and 67 are provided so as to straddle the outer peripheral surface and the back surface of the enlarged heads 70 and 71 of the valve bodies 45 and 50. , 71 having a smaller outer diameter than the maximum diameter portion on the side opposite to the seating portion seated on the valve seat 49 has an effect of promoting the communication action of the communication means 52, 53 for preventing containment of hydraulic oil. The use of the communication means 52, 53 as the grooves 58, 59 formed on the inner surfaces of the valve chambers 42, 47 can prevent the strength of the spool 22 from being reduced.

FIG. 3 shows a third embodiment of the present invention.
The difference from the first embodiment is that the communication means 52, 53
Correspond to the holes of the outlet passages 46 and 51, respectively.
9 is the through holes 60 and 61 provided on the opposite side. These through holes 60 and 61 are circular holes smaller than the circular holes of the outlet passages 46 and 51.

In this embodiment, when the actuator passage 33 is sucked when the spool 22 returns to the neutral position, the check valve body 50 moves in the valve opening direction, and the back of the enlarged head 71 is connected to the outlet passage 51. Since the through-hole 61 exists even when reaching the vicinity of the edge opposite to the valve seat 49 of the circular hole of the enlarged head 71,
The hydraulic oil is not confined in the valve chamber 47 on the back side of the valve body 50, and the valve body 50 further moves in the valve opening direction to fully open the valve. This prevents cavitation as in the first embodiment. Also, when the spool 22 returns to the neutral position from the opposite direction, the check valve 23 operates in the same manner to prevent cavitation. Communication means 5
Since the through holes 60 and 61 are used as the through holes 60 and 61, the communicating means can be provided by an easy process, and the through holes are smaller than the circular holes of the outlet passages 46 and 51. Can be.

FIG. 4 shows a fourth embodiment of the present invention.
The difference from the first embodiment is that the communication means 52, 53
However, the point is that a passage is formed by grooves 62 and 63 in the axial direction on the outer peripheral side of the portions of the valve bodies 45 and 50 that are seated on the valve seats 44 and 49. In this embodiment, the spool 22
When the actuator passage 33 side is sucked when the valve returns to the neutral position, the check valve body 50 moves in the valve opening direction, and the back surface of the enlarged head 71 is opposite to the valve seat 49 of the circular hole of the outlet passage 51. Even when reaching the vicinity of the edge, since the groove 62 is present, the hydraulic oil is not confined in the valve chamber 47 on the back side of the enlarged head 71, and the valve body 50 is further moved in the valve opening direction and is sufficiently moved. To open. This prevents cavitation as in the first embodiment. Also, when the spool 22 returns to the neutral position from the opposite direction, the check valve 23 operates in the same manner to prevent cavitation. The communicating means 52, 53 are connected to the grooves 62, 63 on the outer peripheral portions of the valve bodies 45, 50.
The valve opening can be increased without changing the structure of the spool 22, and the strength of the spool does not decrease.

[0026]

According to the first aspect of the present invention, since the communicating means is formed, it is possible to prevent the occurrence of cavitation due to the suction of the hydraulic oil by the inertial force when the actuator stops. According to the second aspect of the present invention, since the communication means is formed as a notch, an increase in the size of the opening of the outlet passage is suppressed, so that a decrease in the strength of the spool can be almost eliminated. The third aspect of the invention has an effect of suppressing a decrease in the strength of the spool. According to the fourth aspect of the present invention, since the communication means can be easily processed by the through hole, there is an effect that the manufacturing cost is advantageous. The invention described in claim 5 has an effect of suppressing a decrease in the strength of the spool. The invention according to claim 6 has an effect that the strength of the spool does not decrease at all because the communication means is provided in the valve body. The invention according to claim 7 is
The small diameter portion acts as a communication means by itself, but the use of the other communication means together with the other communication means promotes the communication action of the other communication means, thereby ensuring that the check valve is sufficiently opened. Play.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a longitudinal sectional front view, and FIG. 1B is a partially developed view of an outer peripheral surface of a spool near one check valve outlet passage.

FIG. 2 is a vertical sectional front view of a main part showing a second embodiment of the present invention.

FIG. 3 is a vertical sectional front view of a main part of a spool showing a third embodiment of the present invention.

FIGS. 4A and 4B show a fourth embodiment of the present invention, wherein FIG. 4A is a longitudinal sectional front view of a main part, and FIG. 4B is an end view of a valve body of one check valve viewed from a head side. .

FIG. 5 shows an example of a conventional counterbalance valve,
(A) is a longitudinal sectional view, (b) is a transverse sectional view.

[Explanation of symbols]

 REFERENCE SIGNS LIST 20 counter balance valve 21 main body 22 spool 23 check valve 24 check valve 25 spool hole 26 pump 27 tank 29 supply / discharge passage 30 supply / discharge passage 31 actuator 32 actuator passage 33 actuator passage 34 pressure chamber 35 pressure chamber 42 pressure chamber 42 inlet Passageway 44 Valve seat 45 Valve element 46 Outlet path 47 Valve chamber 48 Inlet path 49 Valve seat 50 Valve element 51 Outlet path 52 Communication means 53 Communication means 54 Notch 55 Notch 56 Main valve 58 Groove 59 Groove 60 Through hole 61 Through hole 62 Notch (passage) 63 Notch (passage) 66 Slope 67 Slope 68 Small diameter part 69 Small diameter part 70 Enlarged head 71 Enlarged head

Continuation of the front page (56) References JP-A-7-229569 (JP, A) JP-A-3-20181 (JP, A) JP-A 4-86909 (JP, U) JP-A 57-119171 (JP) , U) Fully open sho 56-146169 (JP, U) Fully open flat 4-25075 (JP, U) Fully open flat 1-154373 (JP, U) Fully open 1979-71822 (JP, U) 6-67970 (JP, U) JP-A 63-196875 (JP, U) JP 2-21659 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16K 17/04 F16K 3/24 F16K 47/02

Claims (7)

(57) [Claims] 1. A main body having a spool hole, a spool slidably inserted into the spool hole, a supply / discharge passage formed in the main body and connected to a pump or a tank, and an actuator passage connected to an actuator. And a check valve provided in the spool and having a forward direction from the supply / discharge passage toward the actuator passage,
The check valve, a valve chamber formed inside the spool,
An inlet passage communicating the valve chamber with the supply / discharge passage, a valve seat formed at an opening of the inlet passage to the valve chamber, a valve body seatable on the valve seat, and the valve chamber. In a counterbalance valve having an outlet passage communicating with an actuator passage and having an opening facing a side surface of the valve body, the actuator passage and the actuator passage are provided on an opposite side of the valve seat of an opening of the outlet passage to the valve chamber. A counterbalance valve having communication means for communicating with a valve chamber. 2. The counterbalance valve according to claim 1, wherein said communicating means is a notch extending from an opening edge of said outlet passage to said valve chamber toward a side opposite to said valve seat. 3. The counterbalance valve according to claim 2, wherein the notch is a groove formed on the inner surface of the valve chamber. 4. The counterbalance valve according to claim 1, wherein the communicating means is a through hole provided on an opposite side of the opening of the outlet passage to the valve chamber from the valve seat. 5. The counterbalance valve according to claim 4, wherein an opening area of the through hole is smaller than an opening area of the outlet passage to the valve chamber. 6. The communication device according to claim 1, wherein the communication means is a passage provided on an outer peripheral side of a portion of the valve body seated on the valve seat.
The counterbalance valve as described. 7. The valve body has an enlarged head on which a seating portion for sitting on the valve seat is formed, and the outer diameter of the enlarged head on the opposite side to the seating portion is the maximum diameter of the enlarged head. 6. The counterbalance valve according to claim 1, wherein the diameter is smaller than the outer diameter.