JPH03163202A - Hydraulic circuit - Google Patents

Abstract

PURPOSE:To prevent, when a plurality of control valves are simultaneously operated and one of them is switched for deceleration, acceleration of actuators connected to other operational valves by opening a bleed-off valve for a period and by an opening corresponding to a differentiated value of an operation stroke. CONSTITUTION:A bleed-off valve 2 and a plurality of control valves 3 are parallelly connected to discharge passage 1a of a pump, 1 while a discharge rate of the pump 1, opening of the bleed-off valve 2, and opening of the operational valves 3 are controlled by means of a controller 5 based on operation stroke signals of connection levers 4. When the levers 4 are operated for deceleration, the bleed-off valve 2 is opened for a period and by an opening corresponding to the differentiated value of the operational stroke. The excessive flow amount caused by response delay for the change of pump discharge rate is flowed to the side of a tank by means of the bleed-off valve 2 to prevent acceleration of actuators 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic circuit that supplies pump discharge pressure oil to a plurality of actuators.

[Conventional technology]

As shown in FIG. 2, a bleed-off valve 2 and a plurality of operating valves 3 are connected in parallel to the discharge path 1a of the pump 1, and an operating lever 4
input the operation signal to the controller 5 as an electric signal,
A hydraulic circuit is known in which the bleed-off valve 2, the operation valve 3, and the pump discharge amount are switched as shown in FIGS. 3 and 4 in response to the operation signal to supply pump discharge pressure oil to the actuator 6. There is.

[Problem to be solved by the invention]

With such a hydraulic circuit, when the operation valve 3 is in the neutral position, the pump discharge amount is reduced and the opening degree of the bleed-off valve 2 is increased to allow the discharge pressure oil to flow out to the tank side, so that the drive horsepower of the pump 1 is reduced. However, there are the following issues.

The bleed-off valve 2 corresponds to the operating stroke of the operating lever 4.
Since the opening degree of the control valve 3, the opening degree of the operating valve 3, and the discharge amount of the pump 1 are set in a fixed relationship, the plurality of operating valves 3 are operated simultaneously to supply discharge pressure oil to the plurality of actuators 6. In this state, when one operation lever 4 is operated to the neutral position or toward the neutral position, the response speed of the discharge amount change of the pump 1 is slow compared to the response speed of the operation valve 3 and the bleed-off valve 2, and the flow rate is transient. The excess may flow into other actuators 6 and accelerate them.

Therefore, an object of the present invention is to provide a hydraulic circuit that can solve the above-mentioned problems.

[Means and actions for solving the problem] When the imaging lever is operated to the deceleration side, the bleed-off valve is opened for a time and opening degree corresponding to the differential value of the operation stroke, thereby changing the pump discharge amount. This allows surplus flow due to response delay to flow out from the bleed-off valve to the tank side.

〔Example〕

The controllers shown in FIG. 2 are equipped with a differential calculation function to calculate the operating stroke of the operating lever 4, the opening degree C1 of the bleed-off valve 2, and the opening time D of the bleed-off valve 2 using the following formula.
Output to.

kl+k2 is a constant.

However, the opening degree C1 and opening time D of the bleed-off valve 2 are calculated and output when the operating lever 4 is operated at the neutral position or toward the neutral position, that is, when it is operated toward the deceleration side.

As a result, an opening signal is manually applied to the bleed-off valve 2 for a time corresponding to the differential value, the opening is opened by the opening degree for a time corresponding to the differential value, and the excess flow due to the delay in response to changes in pump discharge amount is removed from the bleed-off valve. 2 to the tank side, thereby preventing other actuators 6 from accelerating.

If the above operation is represented graphically, it will look like Figure 1, and Figure 2.
When the operation lever is decelerated (a), the bleed-off valve 2 opens at the opening degree C and time D, and the surplus flow rate (b) is shown by diagonal lines.
) drains into the tank.

〔Effect of the invention〕

When the operation lever 4 is operated to the deceleration side, the bleed-off valve 2 is opened for the time and opening degree corresponding to the differential value of the operation stroke, so the excess flow due to the response delay of the pump discharge amount change is released from the bleed-off valve 2. Since it can flow out to the tank side, when a plurality of operating valves are operated simultaneously and one operating valve is switched to the deceleration side, actuators connected to other operating valves can be prevented from being accelerated.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the opening/closing control of the bleed-off valve according to the present invention, Figure 2 is a hydraulic circuit diagram, and Figures 3 and 4 are changes in the bleed-off valve opening, pump discharge amount, and operation valve opening. This is a chart showing the following. 1 is a pump, 2 is a bleed-off valve, 3 is an operating valve, 4 is an operating lever, and 5 is a controller.

Claims (1)

[Claims] A bleed-off valve 2 and a plurality of operation valves 3 are connected in parallel to the discharge path 1a of the pump 1, and a controller 5 controls the pump discharge amount and the opening of the bleed-off valve 2 according to the operation stroke signal of the connection lever 4. In a hydraulic circuit that controls the opening degree of the operation valve 3, when the operation lever 4 is operated to the deceleration side, the bleed-off valve 2 is opened by the opening degree for a time corresponding to the differential value of the operation stroke. A hydraulic circuit characterized by: