JPH02204688A - Hydraulic control circuit device - Google Patents

Abstract

PURPOSE:To supply pressure oil forcedly in use of return back pressure as well as to make improvements in suction capacity for a supply portion by installing a pipeline guiding the pressure oil to a second inlet port of a hydraulic pump from a spot short of a back pressure valve giving the back pressure to a return pipeline for a tank. CONSTITUTION:When a hydraulic pump 4 is driven, a hydraulic fluid out of a tank 1 is sucked out of a first inlet port 5 via a strainer 2 and a suction pipeline 3, and pressure oil is discharged via a discharge pipeline 7, driving an actuator. Return pressure oil out of the actuator and a relief valve 8 returns to the tank 1 as being given back pressure by a return pipeline 9 at a check valve 10, while a part of it is sucked in a second inlet port 6 of the hydraulic pump 4 via a branch pipeline 11 and a throttle valve 12, and forcedly supplied. Thus, at time of low temperature or high speed rotation, the pressure oil is forcedly supplied in use of back pressure, so that improvement in suction capacity for a supply quantity portion is promotable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic control circuit device that improves the suction performance of a hydraulic pump at low temperatures or at high speeds.

(Prior art) In conventional general hydraulic control circuit devices, the pump suction port is connected to a tank, and negative pressure is created at the pump suction port.At low temperatures or high speed rotation, the negative pressure value becomes large, resulting in poor suction and manual vibration. Due to the occurrence of turbulence, the noise increased and the pump discharge rate was poor, resulting in poor workability.

(Problems to be Solved by the Invention) In conventional hydraulic control circuit devices, in order to improve the suction performance of the hydraulic pump at low temperatures or high speed rotation, the tank is placed above the hydraulic pump, or the tank is of a sealed structure. The generation of negative pressure at the hydraulic pump intake was suppressed by pressurizing the pump. However, when doing so, there are problems such as system design limitations, a complicated tank structure, and the need for a pressurizing device.

An object of the present invention is to provide a hydraulic control circuit device that is capable of improving the suction performance of a hydraulic pump by using its own tank return back pressure without being subject to any restrictions such as tank arrangement or pressurizing device. There is a particular thing.

(Means for Solving the Problems) Therefore, the present invention has solved the problems of the conventional products described above by providing a hydraulic control circuit device according to the claims.

(Embodiment) Next, a hydraulic control circuit device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram showing another embodiment of the present invention. In the present invention, when one hydraulic pump 4 having two suction ports is driven by an electric motor or an engine, the tank 1
An actuator and a control valve (not shown) are configured to suck hydraulic oil from the first suction port 5 through the strainer 2 and the suction pipe line 3, and discharge pressure oil to the discharge pipe line 7 to drive the actuator. Return pressure oil from the relief valve 8 (only relief valve 8 is shown) is led to return line 9. In the present invention, the pressure oil is returned to the tank 1 through a back pressure valve 0, for example, a check valve 10, which applies back pressure to the return pipe 9, and a part of the return pipe 9 is branched to form a pipe 11 and a throttle valve. 12 to the second suction port 6 of the hydraulic pump 4.

Due to this connection, a back pressure of, for example, about 1.5 to 3 kgf/cd is generated in the pipeline 11 by the check valve lO, and a part of the pressure oil returns via the throttle valve 12 to the second suction port 6 of the hydraulic pump 4. The suction performance of the hydraulic pump improved.

FIG. 2 shows a hydraulic control circuit provided with a throttle valve 13 as a back pressure valve for generating back pressure in the return line. The operation at this time is similar to that of the check valve 10 shown in FIG. 1, so the explanation will be omitted. Note that the throttle valve 12 in FIGS. 1 and 2 is the second
If the flow rate to the suction port 6 becomes a large portion of the pump discharge amount, the exchange of the hydraulic oil in the pipe becomes insufficient, causing an increase in the oil temperature in the pipe.
This is to limit the amount of replenishment to the second suction port 6 because the deterioration of the hydraulic oil progresses.

(Effects of the Invention) According to the present invention, in addition to suction from the first suction port of a single hydraulic pump having two suction ports, it is forced to return to the second suction port using back pressure. By replenishing pressurized oil, the suction performance improves by the amount of replenishment, and the problem of suction failure at low temperatures or high speeds that previously occurred can be resolved without being restricted by tank placement or pressurizing equipment. It provided a control circuit.

[Brief explanation of the drawing]

1 and 2 respectively show hydraulic circuit diagrams showing different embodiments of the hydraulic control circuit device of the present invention. DESCRIPTION OF SYMBOLS 1... Tank, 4... Hydraulic pump, 5... First suction port, 6... Second suction port, 9... Return pipe line, l
O... Check valve (back pressure valve), 13... Throttle valve (back pressure valve) whistle 1 Oral representative Patent attorney Kawauchi Jun procedure procedure book (spontaneous) March 29, 1999

Claims (2)

[Claims] (1) The first of one hydraulic pump with two suction ports
The suction port of the hydraulic pump is connected to a tank, and a back pressure valve that provides back pressure is provided in a return line in which the pressure oil discharged from the hydraulic pump returns to the tank, and connected to the tank. A hydraulic control circuit device comprising a conduit leading to a second suction port of a pump. (2) The hydraulic control circuit device according to claim 1, wherein the back pressure valve is a check valve or a throttle valve.