JPS5965602A - Hydraulic drive controller for internal body - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a rocking back phenomenon in an inertial body, by bringing down the setting pressure of a bypass relief valve to some extent by degrees in time of braking the inertial body, while reducing the braking force automatically and continuously. CONSTITUTION:A solenoid selector valve 22 and a relief valve 23 both are connected to the bent port of a bypass relief valve 21 of a brake valve 5, while the upstream side of the relief valve 23 is connected to a chamber 28 where the pressure receiving area of a differential cylinder 27 is large, then a primary side port of the bypass relief valve 21 is connected to another chamber 29 where the pressure receiving area of the differential cylinder 27 is small, and furthermore a piston 34 of the said cylinder 27 is connected to a spring 35 of the relief valve 23. With this method, in time of braking, the solenoid selector valve 22 is changed to a position B whereby the piston rod 34 goes to the left and the setting pressure of the relief valve 23 is gradually brought down to some extent, so that braking force is reduced automatically and continuously, thus a rocking back phenomenon in an inertial body can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for driving and then braking a large load (hereinafter referred to as an inertial body) such as a large excavator using hydraulic pressure.

An example of this type of conventional device will be explained with reference to FIG.
(1) is a hydraulic pressure source, (2) is a flow control valve, and (3).

(4) is a counterbalance valve, (5) is a brake valve, (6) is a hydraulic motor, and (7) is a brake valve (5).
The vent circuit is connected to the vent port of the bypass relief valve (8) built into the vent circuit, and includes an electromagnetic switching valve (9) and an IJ-F valve (10) downstream thereof. In this conventional device, the flow control valve (2) is set at position A, for example, and the hydraulic fluid from the hydraulic pressure source (1) is guided to the hydraulic motor (6) via the flow path (11). The discharged liquid is returned to the tank (131) through the flow path (121, counterbalance valve (4), and flow rate control valve (2), and the inertial body (not shown) is driven in one direction by the hydraulic motor (6). The flow control valve (2) is used to stop the drive while it is being driven.
When the hydraulic motor (6) is returned to the neutral position, the hydraulic fluid from the hydraulic pressure source (1) returns from the flow control valve (2) to the tank (131) and does not drive the hydraulic motor (6). In order to pump the tank-side hydraulic fluid sucked in from the flow path OD by the inertia of the flow path (12j),
The hydraulic pressure on the side increases. On the other hand, when the flow control valve (2) is returned to the neutral position, the pilot pressure of the counterbalance valve (4) decreases to approximately tank pressure 1, and becomes lower than the set pressure of the bypass IJ IJ-F valve (8). from the hydraulic motor (6
) and the counterbalance valve (4) reaches the set pressure of the bypass valve (8), the hydraulic fluid flows through the relief valve (8), check valve (14), and flow path ( 1
1), hydraulic motor (6), flow path (121, check valve (
15) and the relief valve (8), and the hydraulic motor (6) is braked. In this case, if the vent circuit (7) is missing, the bypass IJ IJ-F valve (
8) is closed and the hydraulic motor (6) stops, the hydraulic pressure between the hydraulic motor (6) and the counterbalance valve (4) is the set pressure of the bypass valve (8). As a result, a large pressure difference is created between the hydraulic pressure in the flow path (11) (approximately tank pressure), and the hydraulic motor (6) immediately stops and begins to reverse with an inertial body. (Swinging back phenomenon of inertial body).

In this regard, the bypass relief valve (8) is provided with a vent circuit (7) as shown in the figure, and its electromagnetic switching valve (9) switches from position B to position A when the flow control valve (2) returns to the middle position. If the setting pressure of the bypass IJ-F valve (8) during braking is given by the IJ-F valve (10), the set pressure of this IJ-F valve (10) can be directly set. Alternatively, the inertial body swing back phenomenon can be eliminated by gradually reducing it by remote control and sufficiently lowering the setting force when the inertial body stops. However, in operating this relief valve, the determination of the size of the inertial body, selection of braking time, etc. all depend on the operator's intuition. This may cause problems such as the hydraulic motor (6) reaching a dangerous speed and causing the swing mechanism to run out of control, or conversely, increasing the speed too high and causing the hydraulic motor (6) to suddenly stop and applying shock to the swing mechanism. This requires considerable skill to operate.

The present invention has been made in order to improve the above-mentioned drawbacks, and in a hydraulic drive/brake circuit that includes a brake valve in a hydraulic motor connected to an inertial body, the primary side port of the relief valve for bypassing the brake valve is connected to the brake valve. It communicates with the chamber with a small pressure receiving area of the differential cylinder, and the vent port of the bypass relief valve is connected to the chamber with a large pressure receiving area of the differential cylinder and the primary side port of another IJ leaf valve via a switching valve. At the same time, a spring that regulates the set pressure of this relief valve is connected to the piston rod of the differential cylinder, and the switching valve maintains low pressure except for communicating its secondary port with the vent port in response to a hydraulic motor stop operation signal. The vent port is connected to a circuit to block the vent port.

The present invention will be specifically described below based on embodiments shown in the drawings. In FIG. 2, (1) is a hydraulic pressure source, (2) is a flow control valve 1. (3), ' (4) are respectively counterbalance valves, (5) is a brake valve, and (6) is a hydraulic motor, which moves from the neutral position to position A or position B by operating the flow control valve (2). Switch the hydraulic fluid from the hydraulic pressure source (1) to the flow path (
11) or (12) to the hydraulic motor (6), and the discharge liquid from the hydraulic motor (6) is directed to the flow path (+21, counterbalance valve (4) or flow path (11), counterbalance valve (3). ) (5), the flow rate control valve (2), the return flow path ([6), and the structure in which the flow is returned to the tank (13) is the same as the conventional circuit shown in FIG.

In this embodiment, the solenoid switching valve (22) is connected to the vent port of the bypass relief valve (21) of the brake valve (5).
) and a vent circuit (24) with an IJ~F valve f23) interposed downstream thereof, and a solenoid switching valve (22
) and the relief valve (23) are connected to a chamber (28) with a large pressure receiving area of the differential cylinder (27) by a passage (26), and the pressure receiving area of the differential cylinder (2r) is The small chamber (29) is connected by a passage (33) interposed with a slow return check valve (321), which is composed of a check valve (30) and a variable throttle valve (31) arranged in parallel to prevent fluid flow from this chamber. The bypass relief valve (2υ communicates with the primary side port, and the differential cylinder (2η) piston rod (34) is connected to the spring (35) that regulates the set pressure of the relief valve (23), and the relief valve &3) is changed by moving the piston rod (34).

Therefore, when the flow rate control valve (2) takes position A or position B, that is, when the electromagnetic switching valve (2) takes the id position A while the hydraulic motor (6) is driving, the secondary side In addition to communicating the port with the tank (13), bypass IJ IJ-
When the vent port of the flow control valve (21) is blocked and the flow control valve (2) assumes the neutral position, the solenoid (3G) is energized by the hydraulic motor stop J-operation signal and assumes position B, and the secondary side The port is connected to the vent port, and after a predetermined period of time, it is demagnetized and returns to position A.

In addition, the ratio of the pressure receiving area of the differential cylinder (27) is selected as an appropriate value based on the magnitude of the impact pressure based on the inertial force of the inertial body and the bypass flow rate of the bypass relief valve (21) that absorbs the impact energy. .

Next, the operation of this embodiment will be explained. Now, when the flow control valve (2) is moved from the neutral position to position B, the hydraulic pressure source (1)
The hydraulic fluid flows into the hydraulic motor (6) through the flow path C (37), the flow rate control valve (2), the flow u (1'll), the check valve (1η) of the counterbalance valve (4), and The liquid discharged from the hydraulic motor goes through the flow path (I), the counterbalance valve (3), the flow control valve (2), and the return flow path (1 (Q) and returns to the tank (13J). It is driven in one direction by the motor (6), and brake fluid pressure is applied between the hydraulic motor (6) and the counterbalance valve (3).This brake fluid pressure is applied to the check valve (38J) and the slow return check valve (
The differential cylinder (27) passes through the check valve (30) of 321.
), and on the other hand, the chamber (28) communicates with the tank (13) via the electromagnetic switching valve (2 (2)) which assumes position A. Located at the end, set the set pressure of the relief valve to the maximum.When this inertial body is driven, the set pressure of the bypass IJ IJ-] valve (21) is set to the maximum because the vent port is blocked. The set pressure is sufficiently higher than the set pressure of the counterbalance valve (3) that takes the pump hydraulic pressure in the flow path (12) as the pilot pressure.Here, in order to stop driving the hydraulic motor (6), the flow rate When the control valve (2) is placed in the neutral position, the electromagnetic switching valve (22) takes position B by the switching signal (hydraulic motor stop operation signal of the flow rate control valve (2)), and the bypass relief valve (21) is switched to position B. As a result of communicating the vent port 1 with the relief valve +231 and the chamber (28) of the differential cylinder (27), the setting pressure of the bypass IJ IJ-F valve (2υ) is given by the relief valve (23), and this relief valve ( The set pressure of 23) is gradually reduced by the piston rod (34) which receives the hydraulic pressure of the flow path (12) before and after the piston (39) and moves to the left based on the difference in pressure receiving area.Therefore, the 1-bypass relief valve ( The set pressure 21) decreases as the piston rod (34) moves to the left.

On the other hand, when the flow control valve (2) assumes the neutral position, the hydraulic pressure source (
The hydraulic fluid from 1) passes through the flow control valve (2) to the tank (1).
Returning to step 3j, the hydraulic motor (6) is damaged by wt + L, but this hydraulic motor pumps by the inertial force of the inertial body.
The tank-side hydraulic fluid sucked from the flow path (12) is transferred to the flow path (11).
), the liquid pressure in the flow path (lυ) increases.In this case, the pilot pressure of the counterbalance valve (3) decreases to approximately the tank pressure, so the bypass IJ IJ-
The pressure becomes higher than the set pressure of the valve (21), and therefore the hydraulic pressure between the hydraulic motor (6) and the counter variable valve (3) becomes IJ.
When the set pressure of the IJ relief valve (21) is reached, the hydraulic fluid flows through the check valve G81, the IJ relief valve 2+1, the check valve (4 (c), the hydraulic motor (6), the check valve (38),
The relief valve (21) is moved and the pressure difference between the load pressure of the hydraulic motor (6) and the set pressure of the bypass IJ valve (2I) causes the hydraulic motor (6) to slip (9). , brakes the inertial body while preventing the impact of the device. During this braking, the set pressure of the bypass relief valve (21) gradually decreases with the left movement of the piston rod (34), that is, with the passage of time, as described above. 6
) can be arbitrarily changed by adjusting the opening of the slow return check valve (3z variable throttle valve (31)).

Therefore, by setting the variable throttle valve 01) to a predetermined opening according to the inertial force of the inertial body, an appropriate braking action can be automatically obtained, and when the inertial body stops, the IJ IJ-F valve ( The set pressure of the second stage is also sufficiently low so that the phenomenon of swinging back of the inertial body does not occur.

Another embodiment shown in FIG. 6 is an example in which a source control method is used in addition to the line control method shown in FIG. The discharge flow path (4) of the variable displacement pump (42) is blocked.
3) is connected to the return flow path (44), and the boost pump (Tsukuda) is used to supply the power source to the circuit (10).Other configurations are the same as those shown in Figure 2. , in order to distinguish them from the parts shown in Fig. 2, corresponding parts are given the same reference numerals with a ``' added to them. In this embodiment as well, when the flow control valve (41) is moved from position A or position B to the neutral position and the inertial body is braked. , hydraulic motor for pumping (
The discharged fluid from d) circulates through the circuit connecting the bypass relief valve (2'+) of the brake (not cut) and the hydraulic motor (d), and the set pressure of the bypass IJ IJ-fu valve (21) is Since the differential pressure gradually decreases as the two piston rods (3'4) move to the left, the same braking action and effect as shown in FIG. 2 can be obtained.

As explained above, in the present invention, the braking force when the inertial body moves can be automatically and continuously reduced, so it is possible to prevent the swinging back phenomenon of the inertial body, and the braking operation is easy. It becomes simple. In addition, since the braking force reduction speed can be arbitrarily selected, there is an excellent effect that smooth braking work without impact force can be obtained by braking according to the iit force of the inertial body.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of a conventional device, and FIGS. 2 and 6 are hydraulic circuit diagrams each showing an embodiment of the present invention. 21.21... Bypass relief valve, 22° ring, 32. ro 2...Slow return check Patent applicant Kawasaki Heavy Industries Co., Ltd. agent Patent attorney Kenzo Ota Figure 2

Claims (1)

[Claims] In a hydraulic drive/braking circuit that includes a brake valve in a hydraulic motor connected to an inertial body, an IJ for bypassing the brake valve is used.
The primary boat of the IJ valve is connected to the chamber with a small pressure receiving area of the differential cylinder, and the vent port of the bypass relief valve is connected to the chamber with a large pressure receiving area of the differential cylinder via a switching valve. - A spring that regulates the set pressure of the relief valve is connected to the primary side port of the relief valve, and a spring that regulates the set pressure of the relief valve is connected to the piston rod of the differential cylinder; An inertial body hydraulic drive control device, characterized in that the vent port is blocked by being connected to a low pressure circuit except when communicated with the vent port by a signal.