KR20030051004A - hydraulic circuit for heavy equipment swing reduction - Google Patents

Abstract

PURPOSE: A hydraulic circuit for decelerating turn in heavy equipment is provided to improve working efficiency by increasing braking force and decreasing braking distance with selectively increasing pressure of a relief valve installed in the turning motor at a stop of the equipment after turning. CONSTITUTION: A hydraulic circuit for decelerating turn is composed of a switch valve installed in a cavitation restricting passage of a turning motor(7) connected to a downstream passage of a pilot relief valve to switch in applying the pilot signal pressure from a remote control valve(11) and obtain braking force by increasing pressure of the relief valve in the turning motor in braking the turning motor, and check valves(8,9) mounted in the lower part of the switching valve and the cavitation restricting passage of the turning motor to increase pressure below the relief valve in braking the turning motor. Braking distance is reduced by increasing pressure of the relief valve selectively in stopping the equipment after turning.

Description

Hydraulic circuit for heavy equipment swing reduction

The present invention relates to a swing deceleration hydraulic circuit for heavy equipment to reduce the turning braking distance by increasing the braking force when the stop after the turning operation due to the driving of the swing motor of heavy equipment such as excavators.

More particularly, the present invention relates to a pivotal deceleration hydraulic circuit for heavy equipment that selectively boosts the pressure of a relief valve installed inside the swinging motor during braking to stop after the swinging operation to secure sufficient braking force and improve workability.

As shown in FIG. 1, the hydraulic circuit for heavy equipment according to the prior art is connected to the main pump 1 and the pilot pump 2 and the main pump 1 to rotate the upper swing body in the left or right direction. Directional valves (3) and pilot pumps are provided in the flow path between the swing motor (7), the main pump (1) and the swing motor (7) to control the stop, rotation and direction change of the swing motor (7). And a remote control valve 11 provided in the flow path between 2) and the direction switching valve 3 to switch the pilot signal pressure discharged from the pilot pump 2 to the direction switching valve 3 for switching.

Reference numerals 12 and 12a denote relief valves for protecting the hydraulic circuit by draining them to the hydraulic tank 18 when the pressure of the hydraulic oil discharged from the pilot pump 2 and the main pump 1 exceeds a set value. It is a hydraulic tank.

In the case where the above-described remote control valve 11 is operated in the left direction in the drawing (in the drawing in FIG. 1, the A direction), the pilot signal pressure discharged from the pilot pump 2 is passed through the remote control valve 11. As it is applied to the left port of the direction switching valve 3 and is switched in the right direction in the drawing, the hydraulic oil discharged from the main pump 10 passes through the position switching direction valve 3 and then the flow path ( 4) is supplied to the swing motor (7), and at the same time the hydraulic oil drawn out from the swing motor (7) is returned to the hydraulic tank (18) via the flow path (10) and the direction switching valve (3) The upper swinging body can be turned.

On the other hand, in the case where the above-mentioned remote control valve 11 is returned to the neutral position by the driver in order to stop the work device at a certain point after the turning operation (the state shown in FIG. 1), the direction switching valve 3 is moved to the neutral position. As it returns, the hydraulic oil discharged from the main pump 1 is drained to the hydraulic tank 18, and the flow paths 4 and 10 between the directional valve 3 and the swing motor 7 form a closed circuit.

At this time, the upper swing body not shown is to maintain the state to be continuously rotated by the inertial force during the turning operation, the pressure inside the flow path 10 is raised to pass through the relief valve 6 and the check valve (8) As a result, the relief pressure acts as a braking force of the swing motor 7.

At this time, if the inertia force of the upper swinging body of the equipment not shown is relatively greater than the braking force of the swinging motor 7, the turning push amount increases, and the driver does not stop the work device at the desired predetermined position, and also the safety of the equipment falls. In view of this, the case of increasing the braking force by increasing the pressure of the relief valves 5 and 6 inside the swing motor 7 to reduce the turning braking distance (determined by the inertia and braking force during braking after turning operation) is reversed. Suddenly, the acceleration performance of the equipment is also increased to have a problem that the braking distance is not reduced.

Accordingly, an object of the present invention is to increase the braking force by selectively boosting the pressure of the relief valve installed inside the swing motor when the work device is stopped after the swing work to increase the braking force, thereby improving the operability of the driver and improving workability. It is to provide a pivotal deceleration hydraulic circuit for heavy equipment.

1 is a hydraulic circuit diagram according to the prior art,

Figure 2 is a swing reduction hydraulic circuit for heavy equipment according to an embodiment of the present invention.

* Explanation of symbols used in the main part of the drawing

One; Main pump

2; Pilot pump

3; Directional Valve

4,10; Euro

7; Turning motor

8,9; Check valve

11; Remote control valve

14; Shuttle Valve

15; Switching valve

16; Check valve

The object of the present invention described above is a main pump and a pilot pump, a swing motor connected to the main pump to drive the upper swing structure, and installed in a flow path between the main pump and the swing motor to rotate, stop, and change the direction of the swing motor. And a remote control valve installed in the swing motor, which is installed in the flow path between the pilot pump and the direction switching valve to apply the pilot signal pressure discharged from the pilot pump to the direction switching valve. Heavy duty turning with check valve to prevent cavitation of motor, relief valve to generate turning and braking force of turning motor, and pilot relief valve installed in discharge path of pilot pump and returning to hydraulic tank when setting pressure is exceeded Cavitation of the swinging motor connected to the downstream flow path of the pilot relief valve in the deceleration hydraulic circuit It is installed in the support flow path and is switched when the pilot signal pressure is applied from the remote control valve, and when the turning motor is braked, the switching valve and the downstream side of the switching valve and the slewing motor cavitation are secured by boosting the pressure of the relief valve in the turning motor It is achieved by providing a swing deceleration hydraulic circuit for heavy equipment, characterized in that it is provided on the downstream side of the prevention flow passage and provided with a check valve for boosting the downstream pressure of the relief valve during braking of the swing motor.

According to a preferred embodiment, there is provided a shuttle valve which is provided in a downstream flow path of the above-described remote control valve and supplies a pilot signal pressure for position switching to the selector valve.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are intended to be described in detail so that those skilled in the art to which the present invention pertains can easily carry out the present invention. It does not mean that the technical spirit and scope are limited.

As shown in FIG. 2, a main pump 1 and a pilot pump 2, a swing motor 7 connected to the main pump 1 to drive an upper swing structure of equipment not shown, and a main pump ( 1) and a direction change valve (3) which is installed in the flow path between the swing motor (7) and controls the rotation, stop and direction change of the swing motor (7), and between the pilot pump (2) and the direction change valve (3). Remote control valve (RCV) 11, which is installed in the flow path of the pilot pump 2 and discharges from the pilot pump 2, is applied to the directional control valve 3 to be switched, and is provided inside the swing motor 7 to swing. Check valves 8 and 9 to prevent cavitation of the motor 7 and relief valves 5 and 6 which generate turning and braking force of the turning motor 7, the pilot pump 2 and the main pump 1. If the pressure of the hydraulic oil discharged from the tank exceeds the set value, drain the hydraulic tank 18 to obtain relief valves 12 and 12a to protect the hydraulic circuit. It is applied to the rotating deceleration hydraulic circuit for heavy equipment, these will be applied substantially the same as shown in Figure 1, so the detailed description of their configuration and operation will be omitted, overlapping reference numerals are indicated to be the same. .

Therefore, according to a preferred embodiment of the present invention, it is provided in the cavitation prevention flow path 13 of the turning motor 7 to be connected to the downstream flow path of the pilot relief valve 12 described above, and to the remote control valve 11 Of the switching valve 15 and the switching valve 15 to secure the braking force by driving when the pilot signal pressure is applied to boost the pressure of the relief valves 5 and 6 in the swing motor 7 when the swing motor 7 is braked. Check valves 16 and 17 installed on the downstream side and downstream of the cavitation prevention flow path 13 of the swing motor 7 to boost the downstream pressure of the relief valves 5 and 6 during braking of the swing motor 7. And a shuttle valve 14 which is provided in a downstream flow path of the remote control valve 11 and supplies a pilot signal pressure for position switching to the switching valve 15.

Hereinafter, the operation of the rotary deceleration hydraulic circuit for heavy equipment according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, when the work device is braked after the turning operation, that is, when the aforementioned remote control valve 11 is returned to the neutral position, it is applied from the pilot pump 2 to the directional valve 3. The pilot signal pressure is cut off to return the directional valve 3 to the neutral position, and the switching valve 15 provided downstream of the remote control valve 11 also returns to the initial position by the elastic force of the valve spring 15a. It is switched.

At this time, the flow path between the aforementioned direction switching valve (3) and the swing motor (7) forms a closed circuit so that the hydraulic oil of the flow path (10) is a relief valve (6) and a check valve (8) installed inside the swing motor (7). Since it is transmitted to the flow path (4) via) it is possible to brake the turning motor (7).

On the other hand, the pilot signal pressure discharged from the above-described pilot pump 2 is connected to the branching points of the switching valve 15 and the check valve 16 provided downstream of the pilot relief valve 12 via the pilot relief valve 12. Since the switching valve 15 is placed in the initial position, it is connected to the flow passage 13 for preventing cavitation of the swing motor 7.

At this time, when the above-mentioned setting pressure of the check valve 16 is set to a pressure equal to or greater than a predetermined value (for example, higher than the pressure in the flow passage 13 at the time of acceleration), the flow passage 13 is turned motor ( Since it is connected to the downstream of the relief valve (6) installed in 7) has the effect of increasing the downstream pressure.

On the other hand, relief valves typically have a back pressure sensitivity, which is the rate at which the relief valve upstream pressure fluctuates with the downstream pressure fluctuations when the back pressure (refering to the downstream pressure of the relief valve) fluctuates by a certain pressure, generally It has a value of 2 to 6 (that is, when the downstream pressure fluctuates to 1 kg / cm 2, the upstream pressure fluctuates to 2 to 6 kg / cm 2).

Therefore, in the case of raising the downstream pressure of the relief valves 5 and 6, the upstream pressure has a value several times higher than that of the downstream pressure. The braking force is related to the relief pressure (refering to the difference between the upstream pressure and the downstream pressure of the relief valve), that is, assuming that the back pressure sensitivity of the relief valve is 1, the downstream pressure of the relief valves 5 and 6 is increased. Even in the case of the above, the pressure difference between the relief valve upstream and downstream is the same.

However, since the back pressure sensitivity of the relief valves 5 and 6 provided in the swinging motor 7 has a value of 2 to 6, the pressure difference between the upstream and downstream sides of the relief valves 5 and 6 is increased to increase the braking force. At this time, a check valve 17 or an orifice (not shown) may be installed downstream of the downstream flow path of the pilot relief valve 12 and the flow path 13 to increase the pressure downstream of the relief valve 6. will be.

As mentioned above, according to a preferable embodiment, it has the following advantages.

When the work device is stopped after the turning operation, the pressure of the relief valve installed inside the swinging motor is selectively increased to increase the braking force, thereby reducing the turning braking distance and improving the operability of the driver and improving workability.

Claims (2)

A main pump and a pilot pump, a swing motor connected to the main pump to drive the upper swing structure, a directional valve installed in a flow path between the main pump and the swing motor to control rotation, stop and direction change of the swing motor; Remote control valve installed in the flow path between the pilot pump and the direction switching valve to switch the pilot signal pressure discharged from the pilot pump to the direction switching valve, and a check valve installed inside the swing motor to prevent the cavitation of the swing motor And a relief valve for generating the turning and braking force of the turning motor, and a pilot relief valve installed in the discharge flow path of the pilot pump to return to the hydraulic tank when the set pressure is exceeded: It is installed in the cavitation prevention flow path of the swing motor connected to the downstream flow path of the pilot relief valve and is driven when the pilot signal pressure is applied from the remote control valve, and the pressure of the relief valve in the swing motor is braked when the swing motor is braked. A switching valve for boosting and securing a braking force; And And a check valve installed downstream of the switching valve and downstream of the cavitation preventing flow path of the swing motor to boost the downstream pressure of the relief valve during braking of the swing motor. Circuit. 2. The pivotal deceleration hydraulic circuit according to claim 1, further comprising a shuttle valve provided in a downstream flow path of the remote control valve to supply a pilot signal pressure for position switching to the switching valve.