JPH08177086A - Hydraulic circuit of hydraulic motor for gyration - Google Patents

Abstract

PURPOSE: To increase the holding torque of a hydraulic motor for a gyratory motion during excavation. CONSTITUTION: A relief valve 29 regulating the maximum pressure of a hydraulic motor 23 for a gyratory motion is a two-stage relief valve which is set for a high pressure when the hydraulic oil is supplied to a pressure-receiving chamber 33 and set for a low pressure when it is not supplied. The pressure of the excavation side chamber of the cylinder for a construction machine is supplied to the pressure-receiving chamber 33 and the relief valve 29 is set at a high pressure during excavation to enlarge the holding torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for driving a turning hydraulic motor of a hydraulic excavator.

[0002]

2. Description of the Related Art As a hydraulic excavator, an upper vehicle body is rotatably attached to a lower vehicle body having a traveling body by a hydraulic motor for turning, and an excavating work machine including a boom, an arm, a bucket, etc. is attached to the upper vehicle body by a boom cylinder, It is known that the arm cylinder and the bucket cylinder are attached so as to be vertically rotatable.

As a hydraulic circuit for driving the turning hydraulic motor, first and second main circuits in which the discharge pressure oil of the hydraulic pump is connected to the first and second ports of the turning hydraulic motor by a turning directional control valve. It is known that one of the first and second main circuits is connected to the tank and a relief valve is provided in the first and second main circuits to regulate the maximum pressure.

With such a hydraulic circuit, when the turning hydraulic motor stops turning, the high-pressure oil in one of the first and second main circuits is relieved by the relief valve when it is reversely driven by the inertial force of the upper body and acts as a pump. As a result, the shock when turning is stopped can be reduced.

For this reason, in the above-mentioned hydraulic circuit, the set pressure of the relief valve is set within a range in which the shock at the time of turning stop can be tolerated, and the holding torque for holding the turning hydraulic motor so as not to turn by an external force. Determined by the set pressure of the relief valve.

[0006]

A hydraulic excavator equipped with an offset excavation work is known. When the offset amount of this excavator is increased, the rotational torque acting on the upper vehicle body during excavation increases. If the rotational torque becomes larger than the holding torque commensurate with the set pressure of the relief valve, the upper vehicle body may turn during excavation.

In order to solve this problem, conventionally, a braking hydraulic motor is provided with a brake device, and when the vehicle is stopped, the braking device is used as a brake to increase the holding torque so that the upper vehicle body does not rotate during excavation. Without providing a device, the upper main body has swung due to the torque lost during excavation.

However, the use of the brake device is not only costly but also requires a switching means for switching between braking and non-braking, which complicates the control system.

Therefore, it is an object of the present invention to provide a hydraulic circuit for a hydraulic motor for turning which can solve the above-mentioned problems.

[0010]

SUMMARY OF THE INVENTION A first aspect of the present invention relates to the first and second hydraulic motors 23 for turning the pressure oil discharged from the hydraulic pump 11.
A turning directional control valve 14 for supplying to the ports 24 and 25,
The first and second ports 24, 2 of the turning hydraulic motor 23
In the hydraulic circuit of the turning hydraulic motor provided with the relief valve 29 for determining the maximum pressure of No. 5, the relief valve 29
Is a two-stage relief valve whose set pressure becomes high when pressure oil is supplied to the pressure receiving chamber 33 and becomes low when pressure oil is not supplied to the pressure receiving chamber 33, and the excavation side chamber of the working machine cylinder is It is a hydraulic circuit of a turning hydraulic motor connected to a pressure receiving chamber 33 of a relief valve 29. A second aspect of the invention is that the discharge pressure oil of the hydraulic pump 11 is supplied to the first hydraulic motor 23 for turning.
.Slewing directional control valve 1 supplied to the second ports 24 and 25
4 and the first and second ports 2 of the turning hydraulic motor 23
In the hydraulic circuit of the hydraulic motor for turning equipped with the relief valve 29 that determines the maximum pressure of 4, 25, when the pressure oil is supplied to the pressure receiving chamber 33 of the relief valve 29, the set pressure becomes low, and the pressure receiving chamber 33 A reverse two-stage relief valve whose set pressure becomes high if pressure oil is not supplied to the load pressure detection port 35 of the turning directional control valve 14 communicates with the tank when the turning directional control valve 14 is in the neutral position. In the supply position, the load pressure detection port 35 is connected to the actuator port, and the load pressure detection port 35 is connected to the pressure receiving chamber 33 of the relief valve 29.

[0011]

[Operation] According to the first invention, when pressure oil is supplied to the excavation side chamber of the working machine cylinder to perform excavation work, the pressure oil in the excavation side chamber is supplied to the pressure receiving chamber 33 and the relief valve 29 is set to a high pressure. Therefore, the holding torque at the time of excavation work is increased and the holding force of the upper vehicle body can be improved. Second
According to the invention described above, when the turning directional control valve 14 is set to the neutral position, the pressure oil is not supplied to the pressure receiving chamber 33 of the relief valve 29, and the pressure is set to a high pressure, and the holding torque when excavating in this state becomes large. The holding power of the upper vehicle body can be improved.

[0012]

[Example] As shown in FIG. 1, an upper vehicle body 3 is rotatably provided on a lower vehicle body 2 equipped with a traveling body 1 by a hydraulic motor for turning, and a boom 4 is mounted on the upper vehicle body 3 by a boom cylinder 5. The boom 6 is rotatably provided up and down, and the boom 6 is provided with an arm 6 rotatably up and down by an arm cylinder 7. The boom 6 is provided with a bucket 8 and a bucket cylinder 9.
The digging work machine 10 is configured so as to be rotatable up and down.

FIG. 2 is a hydraulic circuit diagram showing the hydraulic pump 11.
A work machine directional control valve 13 and a turning directional control valve 14 are provided in parallel in the discharge path 12 of each of the above, and a pressure compensating valve 15 is provided at the inlet side of each directional control valve. It is a conventionally well-known device including a check valve portion 16 and a pressure reducing valve portion 17, and a higher load pressure is detected in the load pressure detection path 18.

The first and second actuator ports 19 and 20 of the turning directional control valve 14 are connected to the first and second main circuits 21 and 2, respectively.
2 through the first and second ports 2 of the hydraulic motor 23 for turning.
4, 25, the first and second main circuits 21, 22 are short-circuited by a short circuit 28 having first and second checks 26, 27, and a relief valve 29 is provided in the short circuit 28. The drain circuit 30 is connected to the first and second main circuits 21 and 22 by the first and second suction valves 31 and 32.

Because of this, the turning directional control valve 1
When 4 is the first supply position A, pressure oil is supplied from the first actuator port 19 to the first main circuit 21, and the second main circuit 22 communicates with the tank from the second actuator port 20. Then, pressure oil is supplied from the second actuator port 20 to the second main circuit 22, and the first main circuit 21 flows out from the first actuator port 19 into the tank. At the neutral position N, the first and second actuator ports are supplied. 19 and 20 are cut off, and the first and second main circuits 2
1, 22 are dead ends.

The relief valve 29 is a two-stage relief valve in which the set pressure is high when the pressure oil is supplied to the pressure receiving chamber 33, and the set pressure is low when the pressure oil is not supplied. It is connected to the bottom side chamber 7a (excavation side chamber) of the working cylinder, for example, the arm cylinder 7.

Next, the operation will be described. Directional control valve 1 for turning
4 is in the neutral position N and the working machine directional control valve 13 is in the second position B.
When pressure oil is supplied to the bottom side chamber 7a of the arm cylinder 7 for excavation work, the pressure in the bottom side chamber 7a of the arm cylinder 7 is supplied to the pressure receiving chamber 33 and the set pressure of the relief valve 29 becomes high. Therefore, the holding torque of the turning hydraulic motor 23 becomes large, and the turning holding force of the upper vehicle body 3 is improved at the time of excavation, so that turning can be prevented.

The relief valve 29, as shown in FIG.
A valve 43 that connects and disconnects the inlet port 41 and the outlet port 42 with the valve body 40, a spring 44 that pushes the valve 43 in the closing direction, and a movable piston 4 that serves as a spring receiver of the spring 44.
5 and the pressure receiving chamber 46 of the movable piston 45 (pressure receiving chamber 3
3) is provided, if the pressure oil is not supplied to the pressure receiving chamber 46, the mounting load of the spring 44 is small and the set pressure becomes low. When the pressure oil is supplied to the pressure receiving chamber 46 and the movable piston 45 is pushed, the spring 44 is The mounting load is large and the set pressure becomes high.

FIG. 4 shows a second embodiment of the relief valve 29.
Is a reverse two-stage relief valve in which the relief pressure is high when the pressure oil is not supplied to the pressure receiving chamber 33 and becomes low when the pressure oil is supplied to the pressure receiving chamber 33.
Is connected to the load pressure detection port 35 of the turning direction control valve 14 by a circuit 34.

The circuit 34 includes a check valve 37 and a throttle 3
6 is provided with a slow return valve 38, and the pressure receiving chamber 3
The pressure oil in 3 is made to flow out slowly.

Next, the operation will be described. Directional control valve 1 for turning
When 4 is in the neutral position N, the load pressure detection port 35 communicates with the tank, and the pressure oil in the pressure receiving chamber 33 of the relief valve 29 flows out to the tank. Therefore, the set pressure of the relief valve 29 becomes high, and during the excavation work, Holding torque increases.

The turning direction control valve 14 is connected to the first supply position A,
When the turning hydraulic motor 23 is driven as the second supply position B, the load pressure detection port 35 communicates with the first actuator port 19 or the second actuator port 20 to introduce the load pressure, and the load pressure is introduced into the pressure receiving chamber 33. When supplied, the set pressure of the relief valve 29 becomes low.

From the above-mentioned state, the load pressure detection port 35 for setting the turning direction control valve 14 to the neutral position N communicates with the tank, but the pressure oil in the pressure receiving chamber 33 of the relief valve 29 is restricted by the throttle 36 of the slow return valve 38. After that, the set pressure of the relief valve 29 becomes a high pressure with a time lag, so that the shock when the turning is stopped can be reduced.

The relief valve 29 is constructed as shown in FIG. That is, the valve seat 51 is slidably inserted into the valve main body 50 formed of a sleeve, and the pressure chamber 52 (the pressure receiving chamber 3 is provided between the valve seat 51 and the valve main body 50).
3) is formed, and the inlet port 53 communicates with the outlet port 55 through the hole 54 of the valve seat 51.

A valve 56 is slidably inserted in the valve main body 50 from side to side, and the valve 56 is formed by a spring 57 into a valve seat 51.
The inlet port 53 and the outlet port 55 are closed by being pressed against and the circuit 34 is connected to the pressure chamber 52.

Thus, when pressure oil flows from the circuit 34 into the pressure chamber 52, the valve seat 51 slides to the right and reaches the position shown in FIG. 5, whereby the valve 56 also moves to the right. Since the mounting load of the spring 57 is small, the relief pressure is low.

When the circuit 34 communicates with the tank, the pressure chamber 52
The pressure oil inside flows out and one end surface 51a of the valve spool 51
The valve spool 51 slides to the left due to the inlet pressure acting on the valve 57, which causes the valve 56 to move in the direction of compressing the spring 57, increasing the mounting load of the spring 57 and increasing the relief pressure.

[0028]

According to the first aspect of the present invention, when the pressure oil is supplied to the excavation side chamber of the working machine cylinder for excavation work, the pressure oil in the excavation side chamber is supplied to the pressure receiving chamber 33 and the relief valve 29 becomes high pressure. As a set, the holding torque at the time of excavation work is increased, the turning holding force of the upper vehicle body is improved, and turning can be prevented.

According to the second aspect of the invention, the turning directional control valve 14 is provided.
When is set to the neutral position, pressure oil is not supplied to the pressure receiving chamber 33 of the relief valve 29 and a high pressure is set, and the holding torque during excavation work in that state is increased, the turning holding force of the upper vehicle body is improved, and turning is performed. Can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a hydraulic excavator.

FIG. 2 is a hydraulic circuit diagram showing a first embodiment of the present invention.

FIG. 3 is a sectional view of a relief valve.

FIG. 4 is a hydraulic circuit diagram showing a second embodiment of the present invention.

FIG. 5 is a sectional view of a relief valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Traveling body 2 ... Lower body 3 ... Upper body 4 ... Boom 5 ... Boom cylinder 6 ... Arm 7 ... Arm cylinder 8 ... Bucket 9 ... Bucket cylinder 11 ... Hydraulic pump 13 ... Working machine directional control valve 14 ... Swing directional control valve 15 ... Pressure compensation valve 23 ... Swing hydraulic motor 24 ... First port 25 ... Second port 29 ... Relief valve 33 ... Pressure receiving chamber 35 ... Load pressure detection port 36 ... Throttle 37 ... Check valve 38 ... Slow Return valve 40 ... Valve body 41 ... Inlet port 42 ... Outlet port 43 ... Valve 44 ... Spring 46 ... Pressure receiving chamber 50 ... Valve body 51 ... Valve seat 52 ... Pressure chamber 53 ... Inlet port 55 ... Outlet port 56 ... Valve 57 ... Spring .

Claims (2)

[Claims] 1. A turning directional control valve 14 for supplying pressure oil discharged from a hydraulic pump 11 to first and second ports 24, 25 of a turning hydraulic motor 23, and first and second turning hydraulic motor 23. In the hydraulic circuit of the turning hydraulic motor provided with the relief valve 29 that determines the maximum pressure of the two ports 24 and 25, when the pressure oil is supplied to the pressure receiving chamber 33, the set pressure of the relief valve 29 becomes high, A two-stage relief valve whose set pressure becomes low unless pressure oil is supplied to the chamber 33, and the excavation side chamber of the working machine cylinder is connected to the pressure receiving chamber 33 of the relief valve 29. Hydraulic circuit. 2. A turning directional control valve 14 for supplying pressure oil discharged from the hydraulic pump 11 to the first and second ports 24, 25 of the turning hydraulic motor 23, and the first and second turning hydraulic motor 23. In the hydraulic circuit of the swing hydraulic motor provided with the relief valve 29 that determines the maximum pressure of the two ports 24, 25, when the pressure oil is supplied to the pressure receiving chamber 33, the set pressure of the relief valve 29 becomes low, If the pressure oil is not supplied to the chamber 33, a reverse two-stage relief valve whose set pressure becomes high, and the load pressure detection port 35 of the turning direction control valve 14 is
The turning direction control valve 14 communicates with the tank when it is in the neutral position, and communicates with the actuator port when it is in the supply position, and its load pressure detection port 35 is connected to the pressure receiving chamber 33 of the relief valve 29. The hydraulic circuit for the turning hydraulic motor.