JPH1122843A - Brake valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably prevent leakage of pressure oil by arranging a block valve which receives oil pressure source side pressure and actuator side pressure and communicates/cuts off the inflow side of a relief valve with/from an oil passage, on the inlet side of the relief valve, and arranging a communicating passage to introduce the oil pressure source side pressure to the block valve side from the upstream side of a check valve. SOLUTION: Pressure oil from a hydraulic pump 1 is supplied in an oil pressure source side oil passage 14A, and a check valve 37A opens. Therefore, while communicating the oil passage 14A with the branch passage 15A1 side, motor driving pressure is communicated with an actuator side oil passage 15A and a supply discharge passage 4A. A block valve 41A is held in a valve closing position (a) by receiving a part of the motor driving pressure by the pressure receiving part 42A side through an oil hole 39A of the check valve 37A, and continuously cuts off the inflow port 29A side of a relief valve 24A from an actuator side oil passage 15A. Therefore, a part of the motor driving pressure can be reliably prevented from leaking to the inflow port 29A side of the relief valve 24A by the block valve 41A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake valve suitable for use in a traveling hydraulic motor provided in a construction machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art In general, construction machines such as hydraulic shovels and hydraulic cranes are driven by a hydraulic actuator such as a hydraulic motor for traveling. A brake valve is attached to the motor, and the brake valve converts the inertial load into thermal energy of pressure oil and absorbs the thermal energy.

The brake valve includes a counterbalance valve provided between a hydraulic source and a hydraulic actuator, a pair of relief valves provided closer to the actuator than the counterbalance valve, and each of the relief valves. And a pair of check valves provided between the control valve and the counter balance valve.

[0004] In a vehicle such as a hydraulic shovel provided with a brake valve according to the prior art of this type, a relief valve is provided by a brake pressure generated by the inertial rotation of a traveling hydraulic motor when the traveling vehicle is suddenly stopped. Is opened, and the pressure oil (brake pressure) passing through the relief valve is converted into thermal energy, thereby applying a braking force while absorbing the inertial force of the vehicle.

However, when the vehicle is suddenly stopped, an impact or the like may be generated due to the opening of the relief valve, which not only gives an unpleasant feeling to the operator of the vehicle but also shortens the life of the hydraulic motor for driving the vehicle and the brake valve. May be caused.

In order to prevent such an impact,
Countermeasures such as setting the pressure of the relief valve low or adopting a relief valve with a shockless mechanism may be taken. However, in this case, there are disadvantages such as a decrease in the driving force of the traveling hydraulic motor when a load is large, such as when climbing a hill or steering, or a decrease in responsiveness due to a drive delay.

Therefore, for example, Japanese Patent Publication No. 7-122441 (WO 93/07394) discloses a brake valve (hereinafter referred to as another prior art) employing a relief valve with a shockless mechanism. In this case, by arranging the check valve and the relief valve coaxially, when the check valve is opened at the start of the hydraulic motor or the like, the check valve closes the inlet side of the relief valve. The motor drive pressure is prevented from acting on the relief valve.

[0008]

In the other prior art brake valve described above, when the check valve is opened by hydraulic oil from a hydraulic source when the hydraulic motor is started, the hydraulic oil at this time is released. As the motor drive pressure is supplied to the actuator (hydraulic motor) side, the check valve in the open state closes the inlet side of the relief valve, so that the relief valve opens with the motor drive pressure. To prevent a delay in starting the hydraulic motor or the like.

However, when an operator such as a hydraulic excavator finely operates the operating lever for traveling and gradually starts the hydraulic motor, the flow rate of the hydraulic oil supplied from the hydraulic power source is not sufficient. In some cases, the check valve does not completely open, and the check valve cannot always close the inlet side of the relief valve. Then, in this case, there is a problem that a part of the motor driving pressure leaks to the relief valve side, which causes a start delay of the hydraulic motor.

The present invention has been made in view of the above-mentioned problems of the prior art. In the present invention, even when the flow rate of the pressure oil supplied to an actuator such as a hydraulic motor is small, a part of the pressure oil at this time is used as a relief valve. Can be reliably prevented from leaking to the side,
It is an object of the present invention to provide a brake valve which can start an actuator with high responsiveness, can surely reduce an impact when a vehicle such as a hydraulic shovel is stopped, and can stop the vehicle smoothly. Aim.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-described problems, the present invention provides a casing, a pair of oil passages provided in the casing and connected between a hydraulic power source side and an actuator side, A counterbalance valve provided near the hydraulic pressure source side and provided in the middle of the pair of oil passages; a pair of relief valves provided near the actuator side and provided between the pair of oil passages; It is provided between the relief valve and the counter balance valve and is provided in the middle of the pair of oil passages, and allows the flow of the pressure oil from the hydraulic pressure source side to the actuator side, and prevents the reverse flow. Applied to a brake valve consisting of a pair of check valves.

A feature of the structure adopted by the first aspect of the invention is that it is provided on the inlet side of the relief valve and receives the pressure on the hydraulic source side and the pressure on the actuator side generated in the oil passage. A closing valve that communicates and shuts off the inflow side of the relief valve with the oil passage, and a communication path that guides the pressure on the hydraulic source side from the upstream side of the check valve to the closing valve side. I did it.

According to the above configuration, when the pressure oil from the oil pressure source is supplied toward the oil passage at the time of starting the actuator, the pressure on the oil pressure source side generated in the oil passage acts on the closing valve through the communication passage. The closing valve is kept closed by receiving the pressure on the hydraulic pressure source side, and keeps the inlet side of the relief valve shut off from the oil passage. During this time, the check valve opens at an opening corresponding to the flow rate of the pressure oil, but the closing valve can keep the inlet side of the relief valve closed regardless of the opening of the check valve.

On the other hand, when the supply of the pressure oil from the hydraulic source is stopped to stop the operation of the actuator, the pressure on the hydraulic source side is greatly reduced, and the check valve is automatically closed. In this state, a brake pressure is generated as a pressure on the actuator side in the oil passage due to an inertial rotation of the actuator and the like, and the closing valve receives the pressure on the actuator side (brake pressure), whereby the closing valve is automatically activated. It is possible to open the relief valve and connect the inflow side of the relief valve to the oil passage.

According to the second aspect of the present invention, a first pressure receiving portion for receiving the pressure on the hydraulic pressure source side through the communication passage is provided to the closing valve, and a first pressure receiving portion is provided on a side opposite to the first pressure receiving portion. And a second pressure receiving portion which is located and receives pressure on the actuator side generated in the oil passage when the check valve is closed.

With this arrangement, the closing valve is held in the closed state when pressure oil (pressure on the hydraulic pressure source side) from the hydraulic pressure source is received by the first pressure receiving portion when the actuator is started, and the closing valve is closed. To the oil passage. During this time, the check valve opens at an opening corresponding to the flow rate of the pressure oil, but the closing valve can keep the inlet side of the relief valve closed regardless of the opening of the check valve. on the other hand,
When the supply of the pressure oil from the hydraulic pressure source is stopped to stop the operation of the actuator, the pressure acting on the first pressure receiving portion is greatly reduced, and the check valve is automatically closed. Then, in this state, the brake pressure is generated in the oil passage as the pressure on the actuator side due to the inertial rotation of the actuator or the like, and when the brake pressure is received by the second pressure receiving portion, the closing valve is moved to the first and second pressure receiving portions. The pressure difference between the pressure receiving portions is pushed toward the first pressure receiving portion, and the closing valve can be opened so that the inflow side of the relief valve communicates with the oil passage.

According to the third aspect of the present invention, the closing valve and the check valve are arranged substantially coaxially with the relief valve.

Thus, the closing valve and the check valve can be arranged coaxially with the relief valve within the casing of the brake valve, and the whole can be arranged in a compact arrangement.

Further, in the invention according to claim 4, the check valve is a bottomed cylindrical poppet valve body, and the closing valve is another closed cylindrical tube that is slidably inserted into the check valve. The communication passage is constituted by an oil hole formed in the check valve.

Thus, the closing valve can be compactly accommodated in the check valve composed of the bottomed cylindrical poppet valve body, and the pressure on the hydraulic power source side is guided into the closing valve through the oil hole formed in the check valve. The closing valve can be driven in the valve closing direction.

According to the fifth aspect of the present invention, an urging means is provided between the check valve and the closing valve to normally urge the closing valve in a valve closing direction, and the urging means is provided for the check valve. Is also used as the urging means.

In this case, the closing means can be constantly urged in the valve closing direction by the urging means, and the check valve can be continuously urged in the valve closing direction.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the brake valve according to the present invention will be described below in detail with reference to the accompanying drawings.

Here, FIGS. 1 to 4 show a case where the brake valve according to the embodiment of the present invention is applied to a traveling hydraulic circuit of a hydraulic shovel.

In FIG. 1, reference numeral 1 denotes a hydraulic pump which constitutes a hydraulic pressure source together with a tank 2; 3 denotes a main relief valve disposed between the discharge side of the hydraulic pump 1 and the tank 2; The maximum discharge pressure of the hydraulic pump 1 is set with the set pressure PA (for example, about 350 kg / cm ² ), and an excess pressure higher than that is relieved to the tank 2 side.

Reference numeral 4 denotes a traveling hydraulic motor which constitutes an actuator. The hydraulic motor 4 comprises a pair of supply / discharge passages 4A, 4A.
B, and the supply / discharge passages 4A, 4B have a pair of main conduits 5A,
It is connected to the hydraulic pump 1 and the tank 2 via a control valve 5B and a control valve 6 described later. The supply / discharge passages 4A, 4B of the hydraulic motor 4 are formed integrally with a casing 12 of a brake valve 11, which will be described later, as shown in FIG.

Reference numeral 6 denotes a traveling control valve provided in the middle of the main pipelines 5A and 5B. The control valve 6 comprises a directional control valve having four ports and three positions as shown in FIG. Is operated to switch the operation lever 6A from the neutral position (a) to the switching positions (b) and (c). Then, the control valve 6 supplies the pressure oil from the hydraulic pump 1 to the supply / discharge passage 4A side of the hydraulic motor 4 via the main pipeline 5A at the switching position (b), and rotates the hydraulic motor 4 in one direction. The return oil from the supply / discharge passage 4B is discharged to the tank 2 via the main pipeline 5B and the like. When the control valve 6 is switched to the switching position (C), the supply direction of the pressure oil is reversed, and the hydraulic motor 4 is driven to rotate in the reverse direction.

Numeral 11 denotes a brake valve of the present embodiment attached to the hydraulic motor 4, and 12 denotes a casing of the brake valve 11.
The casing 12 is formed integrally with the motor casing of the hydraulic motor 4, and the casing 12 is provided with a pair of oil passages 13A and 13B that constitute a part of the main pipelines 5A and 5B.

Here, one end of the oil passages 13A and 13B is connected to the hydraulic pump 1 and the tank 2 via the control valve 6, and the other end is connected to a spool sliding hole 17 to be described later as shown in FIGS. On the other hand, one end of the oil passages 14A and 14B extending in a direction substantially perpendicular to the oil passages 14A and 14B, one end of which is located between the oil passages 14A and 14B and communicates with the spool sliding hole 17, and the other end is connected to the oil passages 14A and 14B. Extend in the opposite direction and are connected to the supply / discharge passages 4A, 4B of the hydraulic motor 4 and are connected to the actuator side oil passages 15A, 15B and the like.
A, 14B and the oil passages 15A, 15B on the actuator side are configured to be communicated and disconnected via check valves 37A, 37B described later.

The oil passages 15A, 1 on the actuator side
5B, as shown in FIGS. 2 and 3, first branch passages 15A1, 15B1 extending substantially parallel to the spool sliding hole 17 toward the later-described check valve housing holes 21A, 21B, and a relief valve described later. A second branch 1 extending substantially in parallel with the branches 15A1 and 15B1 toward the inlet side of 24A and 24B.
5A2, 15B2 and third branch passages 15A3, 15B3 extending in the opposite direction to the branch passages 15A2, 15B2 toward the outlet of the relief valves 24B, 24A that are the other one of the relief valves 24A, 24B. It is attached.

Reference numeral 16 denotes a counterbalance valve provided in the casing 12 at a position midway between the oil passages 14A and 14B on the hydraulic pressure side. The counterbalance valve 16 is integrally formed in the casing 12, as shown in FIG. And a spool 18 slidably inserted into the spool sliding hole 17. The spool 18 communicates with and blocks oil passages 14 </ b> A and 15 </ b> A. Land 18
Land 1 that communicates with and blocks A between oil passages 14B and 15B
8B.

The oil passages 14 are provided at both ends of the spool 18.
Oil chambers 19A and 19B that are always in communication with the casings 12A and 14B are provided between the casing 12 and return oil springs 20A and 20B that constantly bias the spool 18 toward the neutral position in the oil chambers 19A and 19B. It is arranged. And oilway 1
When a pressure difference is generated between the oil chambers 19A and 19B by the pressure oil from the oil pressure chambers 4A and 14B, the spool 18 is slidably displaced leftward and rightward against the return springs 20A and 20B. Are the left and right switching positions (b) from the neutral position (b) in conjunction with the control valve 6 shown in FIG.
(C).

21A and 21B are oil passages 14A,
A pair of check valve receiving holes 21A and 21B are formed in the casing 12 so as to be substantially coaxial with the check valve 14B. One end of the check valve receiving holes 21A and 21B is a branch path of oil passages 15A and 15B as shown in FIG. 15A1 and 15B1
The other end is a branch passage 15A2, 15B of the oil passage 15A, 15B.
It is configured to communicate with 2. Valve seats 22A, 22B for the check valves 37A, 37B are provided between one ends of the check valve receiving holes 21A, 21B and the oil passages 14A, 14B.
Are formed. And the check valve accommodation hole 21A,
When the check valves 37A and 37B are opened, the other ends of the branches 21A and 21B are branched as shown in FIG.
It is configured to allow entry into the inside.

23A and 23B are check valve receiving holes 21.
A pair of relief valve mounting holes 23A and 23B formed in the casing 12 so as to be coaxial with A and 21B.
A and 33B are also used as piston sliding holes.

24A and 24B are the relief valve mounting holes 23.
A shows a pair of relief valves provided in the casing 12 via A, 23B, and the relief valves 24A, 24B are valve guides 25A, 25B, which will be described later, disposed coaxially with the check valves 37A, 37B. The seat cylinders 28A and 28B, the relief valve bodies 30A and 30B, the setting springs 31A and 31B, the free pistons 33A and 33B, and the like constitute a crossover load relief valve with a so-called shockless function.

25A and 25B are relief valves 24A and 24
B is a valve guide serving as a main body of the valve guide 25A.
B shows relief valve mounting holes 23A and 23B as shown in FIG.
It is attached via lids 26A and 26B, and the front end side is disposed so as to face the branch paths 15B3 and 15A3. The oil holes 27A, 2A, which are the outlets of the relief valves 24A, 24B, are provided at the distal ends of the valve guides 25A, 25B.
7B are drilled in the radial direction, and the oil holes 27A, 27B are connected to the branch passages 15B3, 15A3 of the oil passages 15B, 15A to be mated.
Is always in communication with

28A and 28B are valve guides 25A and 25B
A valve seat cylinder as a valve seat member fitted and fixed in the relief valve mounting holes 23A and 23B in opposition to the valve seat cylinders 28A and 28B.
28B is arranged such that the base end faces branch paths 15B3 and 15A3, and the tip end faces branch paths 15A2 and 15B2. The distal ends of the valve seat cylinders 28A and 28B are opened and closed by closing valves 41A and 41B described later.
9A and 29B, and the front end surfaces of the inflow ports 29A and 29B are formed as seat surfaces for the closing valves 41A and 41B.

Reference numerals 30A and 30B denote relief valve bodies slidably provided in the valve guides 25A and 25B for detaching from and seating on the valve seat cylinders 28A and 28B.
B is a setting spring 31A, 3 for setting a relief set pressure of the relief valves 24A, 24B (hereinafter referred to as a valve opening pressure PB).
1B is normally urged in the valve closing direction. As shown in FIG. 3, throttle holes 32A and 32B are formed in the relief valve bodies 30A and 30B in the axial direction.
A, 32B is a valve seat cylinder 28 inside the valve guides 25A, 25B.
A, 28B or the other branch road 15B3, 15A3
With a small channel area.

Here, the relief valve 24 according to the present embodiment
A, 24B are valve opening pressures PB by the setting springs 31A, 31B.
Is the set pressure P of the main relief valve 3 shown in FIG.
A is set in advance to a pressure value lower by, for example, about 5 to 30%, and the brake pressure generated in the oil passages 15A and 15B on the actuator side becomes the valve opening pressure PB (for example, 245 to 3).
When the pressure rises to about 35 kg / cm ² ), the relief valve bodies 30A, 30B separate from the valve seat cylinders 28A, 28B (open) so that the brake pressure is reduced via the other branch paths 15B3, 15A3. The structure is such that the actuator is relieved toward the oil passages 15B and 15A.

33A and 33B are relief valves 24A and 24
B is a free piston constituting an accumulator for relieving B at a low pressure.
Are relief valve mounting holes 23A and 23B as shown in FIG.
The oil storage chamber 34 is slidably inserted between the oil storage chamber 34 and the valve guides 25A, 25B.
A, 34B. And the oil storage chamber 34A,
34B is a spring chamber 35A, 3 in the valve guide 25A, 25B.
5B via communication holes 36A and 36B, and the communication holes 36A and 36B are connected to the spring chamber 35 at the time of low-pressure relief described later.
The free pistons 33A and 33B are displaced in the axial direction along the valve guides 25A and 25B by drawing the pressure in the oil reservoirs A and 35B to the oil storage chambers 34A and 34B.

37A and 37B are counter balance valves 16
And a pair of check valves slidably inserted into the check valve receiving holes 21A and 21B, located between the relief valves 24A and 24B. The check valves 37A and 37B are cylindrical poppet valve bodies with a bottom. The opening end side thereof is disposed so as to be substantially coaxial with the valve seat cylinders 28A, 28B of the relief valves 24A, 24B. In the check valves 37A and 37B, weak springs 38A and 38B as urging means are disposed between the bottoms of the check valves 37A and 37B and the lids of the closing valves 41A and 41B. .

Here, the weak springs 38A and 38B have an extremely small spring load as compared with the setting springs 31A and 31B of the relief valves 24A and 24B, and the check valves 37A and 38B.
37B separates and seats the valve seats from the valve seats 22A and 22B. The check valves 37A and 37B are connected to the weak spring 3
8A and 38B, the valve is normally kept in the closed state.
The pressure oil (for example, brake pressure) on the 5A, 15B side is prevented from flowing in the opposite direction to the oil passages 14A, 14B on the hydraulic pressure source side.

On the other hand, the pressure oil (motor drive pressure) from the hydraulic pump 1 flows into the oil passage 14A on the hydraulic pressure source side as shown by an arrow A shown in FIG.
When the check valve 37A receives the motor drive pressure at this time with the pressure receiving area S1, the check valve 37A opens the valve against the weak spring 38A so that the oil passage 14A communicates with the branch passage 15A1. This motor drive pressure is allowed to flow in the direction of the arrow B to the oil passage 15A on the actuator side.

In the same manner, the check valve 37B is driven by the motor drive pressure from the oil passage 14B side.
4B so as to communicate with the branch path 15B1 side.
B is opened against B, and the motor drive pressure is allowed to flow toward the oil passage 15B on the actuator side.

39A and 39B are check valves 37A and 37
B at the bottom side of the oil holes 39A and 39B.
When the check valves 37A and 37B are closed, the oil passages 14A and 14B upstream of the check valves 37A and 37B are closed by pressure receiving portions 42A and 42 of the closing valves 41A and 41B.
It forms a communication passage communicating with the B side.

40A, 40B are check valves 37A, 37
B is a plurality of notches formed in the opening end of the opening B at intervals in the circumferential direction, and each of the notches 40A and 40B is a check valve 37.
When the valves A and 37B are opened, the open ends of the check valves 37A and 37B are connected to the inlets 29A and 29A of the relief valves 24A and 24B.
Even if the end faces of the valve seat cylinders 28A, 28B abut against the end faces of the valve seat cylinders 28A, 28B, the open ends of the check valves 37A, 37B are prevented from sticking to the end faces of the valve seat cylinders 28A, 28B.

Reference numerals 41A and 41B denote relief valves 24A and 24
B indicates a shutoff valve for communicating and shutting off the inlets 29A and 29B of B with the branch passages 15A2 and 15B2 of the oil passages 13A and 13B, and the shutoff valves 41A and 41B are check valves 37.
A and 37B, each of which is made of a covered poppet valve body having a smaller diameter than that of the inlet valve 29 of the relief valves 24A and 24B.
Check valve 37 so as to be coaxial with A, 29B
A and 37B are slidably inserted in the insides. The closing valves 41A, 41B are normally urged in the valve closing direction by weak springs 38A, 38B disposed between the check valves 37A, 37B and the bottom.

Here, the first pressure receiving portions 42A, 42 are provided between the closing valves 41A, 41B and the check valves 37A, 37B.
B is formed, and the pressure receiving portions 42A, 42B are connected to the oil passages 14A,
By receiving the motor drive pressure from 14B through the oil holes 39A and 39B, for example, when the hydraulic motor 4 is started, the inflow ports 29A and 29B of the relief valves 24A and 24B are kept closed, and the motor drive pressure is reduced. Part is a relief valve 24A,
It is configured to prevent leakage to the inlets 29A, 29B side of the 24B.

In this case, as shown in FIG.
1A is a pressure receiving area S2 corresponding to the inner diameter of the check valve 37A.
To receive the motor drive pressure, and the lid side is the valve seat cylinder 2
8A is pressed toward the end face on the side of the inflow port 29A. on the other hand,
The check valve 37A receives the motor drive pressure flowing from the oil passage 14A side in the direction of arrow A in FIG. 4 with a pressure receiving area S1. The check valve 37A opens against the weak spring 38A due to the pressure receiving area difference between the two (S1-S2).
The motor drive pressure is allowed to flow in the direction of arrow B to the oil passage 15A on the actuator side. The check valve 37B also performs a valve opening operation in the same manner.

Further, 43A and 43B are the first pressure receiving portions 4
The blocking valves 41A, 41 are located on the opposite side to the 2A, 42B.
B is a second pressure receiving portion formed on the outer peripheral side of the lid portion, and the pressure receiving portions 43A and 43B are constituted by tapered chamfered portions provided on the outer peripheral side of the lid portions of the closing valves 41A and 41B. The pressure receiving area S2 of the first pressure receiving portions 42A and 42B (FIG. 4)
See below).

When a brake pressure (pressure on the actuator side) is generated in the oil passages 15A, 15B on the actuator side, for example, during the inertial rotation of the hydraulic motor 4, the second pressure receiving portions 43A, 43B reduce this brake pressure. By receiving the pressure, the closing valves 41A and 41B are moved to the weak springs 38A and 38B.
And the brake pressure at this time is
A, relief valve 2 from inlet side 29A, 29B side of 28B
4A and 24B are allowed to act on the relief valve bodies 30A and 30B.

The traveling hydraulic circuit of the hydraulic excavator provided with the brake valve 11 according to the present embodiment has the above-described configuration. Next, the operation thereof will be described.

First, when the operator of the hydraulic excavator switches the control valve 6 shown in FIG. 1 from the neutral position (a) to the switching position (b) in order to run the vehicle, the hydraulic oil from the hydraulic pump 1 receives the main line 5A. Check valve 37 via (oil passage 13A)
A is supplied to the hydraulic pump 4 from the supply / discharge passage 4A side while the valve A is opened. At this time, the counterbalance valve 1
Reference numeral 6 denotes a differential pressure between the oil passages 13A and 13B, which switches from the neutral position (a) to the switching position (b), and returns the return oil from the supply / discharge passage 4B of the hydraulic pump 4 to the main pipe via the counter balance valve 16. It is discharged from the path 5B (oil passage 13B) to the tank 2.

During this time, the pressure oil (motor driving pressure) from the hydraulic pump 1 is supplied into the oil passage 14A on the hydraulic source side in the direction indicated by the arrow A in FIG. 4, and the check valve 37A is weakened by this motor driving pressure. By opening the valve against the spring 38A, the oil passage 14
A is connected to the branch passage 15A1 while the motor drive pressure is applied to the oil passage 15A and the supply / discharge passage 4A on the actuator side.
To the side in the direction of arrow B.

The closing valve 41A receives a part of the motor driving pressure through the oil hole 39A of the check valve 37A on the pressure receiving portion 42A side, and is held at the valve closing position (a) shown in FIG. Then, the inflow port 29A side of the relief valve 24A is kept shut off from the oil passage 15A (branch passage 15B2) on the actuator side. Therefore, the closing valve 41A can reliably prevent a part of the motor driving pressure from leaking to the inlet 29A side of the relief valve 24A.

On the other hand, when the operator returns the control valve 6 from the switching position (b) to the neutral position (a) in order to stop the running of the vehicle, the pressure on the main pipe line 5A (oil passage 13A) side becomes the tank pressure. Check valve 3
7A and 37B are both closed. Then, the counterbalance valve 16 returns to the neutral position (A) with a decrease in the pressure on the oil passage 13A side, and the oil passages 13A and 13B move the hydraulic pump 1 between the hydraulic motor 4 and the counterbalance valve 16.
And the tank 2 is shut off.

In this case, the hydraulic motor 4 often continues to rotate by inertia due to the inertial force during traveling of the vehicle. During this inertial rotation, even after the control valve 6 has returned to the neutral position (a), the hydraulic motor 4 remains in the oil passage. It performs a pump function of discharging the pressure oil sucked from the 13A side to the oil passage 13B side. The oil passage 15B of the oil passage 13B is actuated by the pump action of the hydraulic motor 4.
A high-pressure brake pressure is generated on the side, and this brake pressure acts on the pressure receiving portion 43B of the closing valve 41B via the branch passage 15B2 of the oil passage 15B, thereby opening the closing valve 41B against the weak spring 38B. Switch to valve position (b).

As a result, the brake pressure in the oil passage 15B is introduced into the valve seat cylinder 28B from the inflow port 29B side of the relief valve 24B, and flows into the spring chamber 35B through the throttle hole 32B of the relief valve body 30B. . The pressure oil that has flowed into the spring chamber 35B is guided to the oil storage chamber 34B through the communication hole 36B of the valve guide 25B, so that the free piston 33B constituting the accumulator is moved in the direction of arrow C in FIG. The volume of the oil storage chamber 34B is expanded by sliding displacement.

As a result, the relief valve 24B is connected to the spring chamber 35.
A allows the relief valve 30B to momentarily open while the pressure in A temporarily decreases and the free piston 33B slides and displaces in the direction of arrow C until the stroke end,
The brake pressure from the inflow port 29B is applied to the oil passage 15A of the other party.
(Branch 15A3) side is made low pressure relief. As a result, the relief valve 24B increases the brake pressure in the oil passage 15B,
A sudden rise due to the inertial rotation of the hydraulic motor 4 is suppressed, and a so-called shockless function is provided.

When the sliding displacement of the free piston 33B reaches the stroke end, the pressure in the spring chamber 35B increases again, and accordingly, the relief valve 30B is caused by the spring force of the set spring 31B. The valve is closed.
Then, in this state, when the brake pressure on the oil passage 15B side rises to the valve opening pressure PB of the relief valve 24B, the relief valve 30B opens against the setting spring 31B, and is discharged from the hydraulic motor 4. The pressure oil is converted into thermal energy while passing between the valve seat cylinder 28B and the relief valve body 30B, and the vehicle is gradually stopped by the brake pressure at this time.

When the traveling control valve 6 is in the neutral position (a).
Is switched to the switching position (C), the oil passage 13B
The motor drive pressure is supplied to the side, and the hydraulic motor 4 is driven to rotate in a direction opposite to the above-described case. Then, when the control valve 6 is thereafter returned from the switching position (C) to the neutral position (A), a brake pressure is generated, for example, on the oil passage 15A side of the oil passage 13A, and substantially the same as in the above-described case. The vehicle is stopped.

Thus, according to the present embodiment, the brake valve 1
The check valve receiving holes 21A, 21
B and the relief valve mounting hole 23A are substantially coaxially opposed to each other. Relief valves 24A and 24B having a shockless function are provided in the relief valve mounting hole 23A, and the check valves 21A and 21B are provided in the check valve receiving holes 21A and 21B. Check valve 37A, 3
7B is slidably provided, and the check valves 37A, 37B have inlets 29A, 29B of the relief valves 24A, 24B.
Since the closing valves 41A and 41B for communicating and blocking B with the oil passages 15A and 15B on the actuator side are slidably inserted, the following operation and effects can be obtained.

That is, the control valve 6 shown in FIG. 1 is moved from the neutral position (a) to the switching position (b) for running the vehicle.
When the pressure oil from the hydraulic pump 1 is caused to flow into the oil passage 14A on the oil pressure source side via the main pipeline 5A, the motor drive pressure at this time is applied to the check valve 37A by an arrow A in FIG. Acts in the direction. As a result, the check valve 37A separates from the valve seat 22A against the weak spring 38A, and the oil passage 14A
Is allowed to flow into the supply / discharge passage 4A of the hydraulic motor 4 via the oil passage 15A on the actuator side, and the motor drive pressure is supplied to the hydraulic motor 4.

Since a part of the motor driving pressure at this time is supplied to the pressure receiving portion 42A of the closing valve 41A through the oil hole 39A of the check valve 37A, the closing valve 41A is maintained in the closed state. As a result, the inflow port 29A side of the relief valve 24A is connected to the oil passage 15A (branch passage 15) on the actuator side.
B2) can be reliably shut off, and a part of the motor drive pressure can be prevented from leaking to the inlet 29A side of the relief valve 24A by the closing valve 41A.

As a result, when an operator such as a hydraulic excavator finely operates the operating lever 6A for running and slowly starts the hydraulic motor 4, the flow rate of the hydraulic oil supplied from the hydraulic pump 1 is sufficient. Therefore, even if the check valve 37A is not completely opened as illustrated in FIG. 4, the closing valve 41A can reliably keep the inlet 29A side of the relief valve 24A closed, and the hydraulic motor 4 can be prevented from occurring. Then, the relief valve 3 in which the motor drive pressure is the main pressure on the hydraulic pump 1 side
(See Fig. 1) can be compensated for rising to the set pressure PA,
The vehicle can be reliably started by the hydraulic motor 4 while supplying a high motor drive pressure to the hydraulic motor 4.

On the other hand, when the operator returns the control valve 6 from the switching position (b) to the neutral position (a) in order to stop traveling of the vehicle, which is an inertia body, the hydraulic motor 4 starts to rotate by inertia. The closing valve 41B is opened by the brake pressure generated in the oil passage 15A on the actuator side, and the brake pressure in the oil passage 15B is reduced to the inlet 2 of the relief valve 24B.
It can be introduced into the valve seat cylinder 28B from the 9B side.

In this case, the relief valve 24B is relieved at a low pressure via the free piston 33B or the like to prevent the brake pressure in the oil passage 15B from rapidly increasing due to the inertial rotation of the hydraulic motor 4. To provide a so-called shockless function, and thereafter, the brake pressure is adjusted by the setting spring 31B to set the opening pressure P of the relief valve 24B.
B, the relief valve 30B is opened against the setting spring 31B to reduce the brake pressure.
The oil can be smoothly relieved to the other oil passage 15A (branch passage 15A3) via each oil passage 27B on the outlet side of 4B.

Thus, the brake pressure generated during the inertial rotation of the hydraulic motor 4 can be converted into heat energy while passing through the relief valve 24B, and the vehicle can be gradually stopped while suppressing the inertial rotation of the hydraulic motor 4. it can. And
In this case, the valve opening pressure PB of the relief valves 24A and 24B is
For example, since the pressure is set to about 245 to 335 kg / cm ² , even when the vehicle is parked or stopped on a slope, both the relief valves 24A and 24B can be kept closed, and the vehicle cannot be stopped on the slope. Problems such as easy movement can be eliminated.

Therefore, according to this embodiment, the hydraulic motor 4
Even when the flow rate of the pressure oil supplied from the hydraulic pump 1 is reduced at the time of start-up or the like, a part of the pressure oil at this time can be reliably prevented from leaking to the relief valves 24A and 24B,
The hydraulic motor 4 can be started with high responsiveness,
The driving force of the vehicle can be increased at an early stage, and the operability and reliability during starting and running can be greatly improved.

When the vehicle starts moving, the relief valve 24
A and 24B can be reliably prevented from operating, so that the valve opening pressure PB of the relief valves 24A and 24B can be freely selected in order to improve the braking and stopping characteristics of the vehicle. When stopped, relief valve 24A, 2
4B can be provided with a low pressure relief to provide a shockless function, and the brake pressure generated in the brake valve 11 can be suppressed to be lower than the set pressure PA of the relief valve 3 on the hydraulic pump 1 side. Impact can be reliably reduced, and the vehicle can be stopped smoothly.

Further, the check valves 37A and 37B are disposed coaxially with the closing valves 41A and 41B so as to be coaxial with the inlets 29A and 29B of the relief valves 24A and 24B.
The relief valve 24 is provided in the casing 12 of the brake valve 11.
A, 24B, check valves 37A, 37B and closing valve 4
1A and 41B can be stored compactly, and the relief valve 24
A, 24B, the inlets 29A, 29B side are closed valves 41A,
The configuration (arrangement relationship) of opening and closing by the 41B can be realized with a simple layout, the entire brake valve 11 can be formed compactly, and the overall size and weight including the hydraulic motor 4 can be reduced.

Further, the closing valves 41A and 41B are slidably inserted into the check valves 37A and 37B, and the urging means of both are used by the weak springs 38A and 38B. It is possible to reduce the size and improve the workability at the time of assembling, and to compactly house the closing valves 41A and 41B in the check valves 37A and 37B, thereby achieving reduction in size and weight.

When the check valves 37A and 37B are driven in the valve opening direction (the direction indicated by the arrow A in FIG. 4) by the motor driving pressure when the hydraulic motor 4 is started, the weak springs 38A and 38B are thereby caused. Since the spring force can be increased by bending and deforming, the closing force by the closing valves 41A and 41B can be increased, and the inflow ports 29 of the relief valves 24A and 24B can be increased.
A and 29B sides can be effectively closed by the closing valves 41A and 41B.

In the above embodiment, the closing valves 41A, 4A
1B has been described as an example in which it is slidably provided in the check valves 37A and 37B. However, the present invention is not limited to this. For example, the oil hole 39 in the hydraulic circuit shown in FIG.
The oil passages 14A, 14B on the hydraulic pressure source side upstream of the check valves 37A, 37B are replaced with the closing valves 4 instead of the check valves 37A, 37B.
A communication path is provided for communicating with the pressure receiving sections 42A, 42B of the first and second pressure receiving sections 41A, 41B.
In this case, the closing valves 41A and 41B and the check valves 37A and 37B do not always need to be arranged to face each other in the axial direction.

In the above embodiment, the brake valve 11 is provided with the relief valves 24A and 24B having a shockless function. However, the present invention is not limited to this. For example, a normal relief valve having no accumulator or the like is provided. A valve may be employed, and various relief valves such as a two-way operation type relief valve may be used. Even in this case, the relief valve can be prevented from operating when the actuator is started, etc., and the relief set pressure of the relief valve can be freely selected in order to improve the braking characteristics and stopping characteristics of the vehicle and the like. It becomes possible.

Further, in the above-described embodiment, the case where the traveling hydraulic motor 4 is used as the actuator has been described as an example. However, the present invention is not limited to this, and for example, a swing provided with a brake valve having a counterbalance valve is provided. And a hydraulic circuit using a hydraulic motor or a rope winch as an actuator. And the present invention is not limited to hydraulic excavators, hydraulic cranes, etc.
The present invention can be widely applied to a brake valve of a construction machine having a traveling or turning hydraulic motor or the like.

[0077]

As described above in detail, according to the first aspect of the present invention, a closing valve is provided on the inlet side of the relief valve, and the closing valve is provided on the side of the hydraulic pressure source generated in the oil passage. Since the pressure is guided from the upstream side of the check valve through the communication passage, even when the flow rate of the pressure oil is small at the time of starting the actuator, etc., it is necessary to reliably close the inlet side of the relief valve by the closing valve. Thus, it is possible to prevent a part of the driving pressure from leaking to the relief valve side. Therefore, it is possible to start the actuator with high responsiveness by eliminating troubles such as the operation of the relief valve at the time of starting the actuator, and to freely set the relief pressure of the relief valve to improve the braking characteristics and the stopping characteristics of the vehicle. The impact when stopping a vehicle such as a hydraulic excavator can be reliably reduced, and the vehicle can be stopped smoothly.

According to the second aspect of the present invention, the first and second pressure receiving portions are provided in the closing valve which communicates and shuts off the inflow side of the relief valve with the oil passage, and the first pressure receiving portion is provided in the first pressure receiving portion. Is configured to receive the pressure on the hydraulic pressure source side through the communication passage and to receive the pressure on the actuator side generated in the oil passage when the check valve is closed on the second pressure receiving portion side. Even when the flow rate of the pressure oil is small, for example, at the time of start-up, the inflow side of the relief valve is reliably closed by the closing valve, and a part of the driving pressure can be prevented from leaking to the relief valve side. Further, when the brake pressure is generated in the oil passage as the pressure on the actuator side due to inertial rotation or the like when the actuator is stopped, the brake pressure is received by the second pressure receiving portion, so that the inlet side of the relief valve is closed. The closing valve can be opened so as to communicate with the oil passage, and the shock at the time of stopping can be reduced by operating the relief valve.

Further, according to the third aspect of the present invention, since the blocking valve and the check valve are arranged substantially coaxially with the relief valve, the blocking valve, the check valve and the relief valve are provided in the casing of the brake valve. Can be arranged compactly, and the size and weight of the entire brake valve can be reduced.

Further, in the invention according to claim 4, the check valve is a bottomed cylindrical poppet valve body, and the closing valve is another closed poppet valve body with a closed cylinder slidably fitted in the check valve. The check valve is formed with an oil hole serving as a communication passage, so that the check valve can be housed in the check valve in a compact manner and the oil hole in the check valve reduces the pressure on the hydraulic source side to the check valve side. The size and weight of the entire brake valve can also be reduced.

Further, according to the fifth aspect of the present invention, since the urging means is provided between the check valve and the closing valve so as to serve also as the urging means for the check valve, the urging means allows the closing valve to be used. It can be normally urged in the valve closing direction, and the check valve can also be continuously urged in the valve closing direction.For example, when the check valve is opened, the urging force of the urging means is increased, and the inlet side of the relief valve is closed. The valve can continue to close effectively.

[Brief description of the drawings]

FIG. 1 is a traveling hydraulic circuit diagram of a hydraulic shovel to which a brake valve according to an embodiment of the present invention is applied.

FIG. 2 is a longitudinal sectional view showing a brake valve in FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a check valve, a closing valve, a relief valve, and the like in FIG. 2;

FIG. 4 is an enlarged sectional view of a main part showing a state in which a check valve in FIG. 3 is opened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump (hydraulic source) 4 Hydraulic motor (actuator) 5A, 5B main pipeline 6 Control valve 11 Brake valve 12 Casing 13A, 13B Oil passage 14A, 14B Hydraulic source side oil passage 15A, 15B Actuator side oil passage 16 Counter Balance valve 21A, 21B Check valve accommodation hole 22A, 22B Valve seat 23A, 23B Relief valve mounting hole 24A, 24B Relief valve 25A, 25B Valve guide 28A, 28B Valve seat cylinder 29A, 29B Inlet 30A, 30B Relief valve body 31A, 31B Setting spring 33A, 33B Free piston (accumulator) 37A, 37B Check valve 38A, 38B Weak spring (biasing means) 39A, 39B Oil hole (communication passage) 41A, 41B Closing valve 42A, 42B First pressure receiving part 43A, 43B 2nd pressure receiving part

Claims (5)

[Claims] 1. A casing, a pair of oil passages provided in the casing and connected between a hydraulic source side and an actuator side, and provided in the middle of the pair of oil passages located on the hydraulic source side. A counterbalance valve, a pair of relief valves positioned between the pair of oil passages located closer to the actuator, and the pair of oils positioned between the respective relief valves and the counterbalance valve. A brake valve, which is provided in the middle of the passage and comprises a pair of check valves that allow pressure oil to flow from the hydraulic pressure source side toward the actuator side and prevent a reverse flow, Valve provided on the side of the oil passage, for receiving and receiving the pressure on the hydraulic pressure source side and the pressure on the actuator side generated in the oil passage to communicate and shut off the inflow side of the relief valve with the oil passage. , Brake valve, characterized in that the pressure of the hydraulic power source side from the upstream side of the check valve has a structure and a communication passage leading to the closure valve side. 2. A first pressure receiving portion for receiving the pressure on the hydraulic pressure source side through the communication passage, a closing portion of the check valve, wherein the first pressure receiving portion is located on a side opposite to the first pressure receiving portion. 2. The brake valve according to claim 1, further comprising: a second pressure receiving unit configured to receive a pressure on the actuator side generated in the oil passage when the valve is closed. 3. 3. The brake valve according to claim 1, wherein the closing valve and the check valve are disposed substantially coaxially with the relief valve. 4. The check valve includes a bottomed cylindrical poppet valve body, and the closing valve includes another closed cylindrical poppet valve body that is slidably inserted into the check valve.
4. The brake valve according to claim 1, wherein said communication passage is constituted by an oil hole formed in said check valve. 5. An urging means is provided between said check valve and said closing valve to constantly urge said closing valve in the valve closing direction, said urging means also serving as the urging means for said check valve. The brake valve according to claim 3, wherein the brake valve is configured to perform the following.