JPH0659604U - Load sensing hydraulic circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] In a load sensing hydraulic circuit equipped with a plurality of actuators, the differential pressure across the throttle is reduced for a specific actuator to suppress power loss. [Configuration] A pressure reducing valve 38 is provided in the load pressure detection oil passage 31 of any one of the actuators 27. A branch oil passage 40 is provided between the pressure reducing valve 38 and the shuttle valve 33, and is connected to the tank 42 via the throttle 41. The outlet side of the shuttle valve 33 is connected to the pump regulator 35.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a load-sensing hydraulic circuit for a construction machine, and more particularly to a load-sensing hydraulic circuit for a construction machine having a plurality of actuators.

[0002]

[Prior art]

 Fig. 2 shows a load sensing hydraulic circuit of a conventional construction machine. The discharge line 2 of the hydraulic pump 1 is branched, and a plurality of actuators 7 and 8 are provided via throttles 3 and 4 and pressure compensation valves 5 and 6. The load pressure detection oil passages 11 and 12 are branched from the load pressure pipe passages 9 and 10 of the respective actuators 7 and 8, and the respective load pressure detection oil passages 11 and 12 are connected to the inlet side of the shuttle valve 13. A regulator oil passage 14 is connected to the outlet side of the shuttle valve 13, and the load pressure of the actuators 7 and 8 is led to the pump regulator 15 through the regulator oil passage 14.

[0003]

[Problems to be solved by the device]

 In the load sensing hydraulic circuit, the flow rate of hydraulic oil supplied to each actuator 7, 8 is expressed by the following equation.

[0004]

[Equation 1]

Here, C, A, and ρ are constant, and ΔP is set by the pump regulator 15. Therefore, it is not possible to change the differential pressure across the throttle with a specific actuator to adjust only the flow rate to a specific actuator. That is, the actuator cannot reduce the difference between the discharge pressure and the load pressure of the hydraulic pump, and cannot suppress the power loss.

Therefore, there arises a technical problem to be solved in order to suppress the power loss by reducing the differential pressure across the throttle with respect to a specific actuator, and the present invention aims to solve this problem. To aim.

[0007]

[Means for Solving the Problems]

 The present invention has been proposed in order to achieve the above-mentioned object. It is provided with a plurality of actuators, each load pressure detecting oil passage is branched from the load pressure detecting oil passage of each actuator, and each load pressure detecting oil passage is shuttled. In the load-sensing hydraulic circuit that connects the inlet side of the valve and the outlet side of the shuttle valve to the pump regulator, install a pressure reducing valve in the load pressure detection oil passage of any actuator, and A branch oil passage is provided between the shuttle valve and the branch valve, and a throttle is provided in the branch oil passage to provide a load sensing hydraulic circuit connected to a tank.

[0008]

[Action]

 If an actuator with a pressure reducing valve in the load pressure detection oil passage is operated independently among multiple actuators, the load pressure is reduced by the set value of the pressure reducing valve, and the load reduced by the shuttle valve to the pump regulator. Pressure is derived. Therefore, the discharge pressure of the hydraulic pump becomes low, and the pressure difference between the discharge pressure of the hydraulic pump and the load pressure of the actuator becomes small.

[0009]

【Example】

 Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. The discharge line 22 of the hydraulic pump 21 is branched, and a plurality of actuators 27, 28 are provided via throttles 23, 24 and pressure compensation valves 25, 26. The load pressure detection oil passages 31 and 32 are branched from the load pressure pipes 29 and 30 of the respective actuators 27 and 28, and the respective load pressure detection oil passages 31 and 32 are connected to the inlet side of the shuttle valve 33. A regulator oil passage 34 is connected to the outlet side of the shuttle valve 33, and the load pressure of the actuators 27, 28 is led to the pump regulator 35 through the regulator oil passage 34. The regulator oil passage 34 is branched into pilot oil passages 36 and 37, which are connected to the spring-loaded ports of the pressure compensation valves 25 and 26.

Further, a pressure reducing valve 38 is provided in a specific actuator for suppressing power loss, for example, a load pressure detecting oil passage 31 of the actuator 27. The pressure on the secondary side of the pressure reducing valve 38 is reduced from the primary side by a constant value set by the spring 39 of the pressure reducing valve 38. A branch oil passage 40 is provided on the secondary side of the pressure reducing valve 38 between the pressure reducing valve 38 and the shuttle valve 33. The branch oil passage 40 is provided with a throttle 41 and is connected to the tank 42. The throttle 41 is provided in order to prevent the primary pressure of the pressure reducing valve 38 from lowering than the secondary pressure due to load fluctuations of the actuator 27, and the secondary pressure of the pressure reducing valve 38 is always set to a value higher than the primary pressure. Control only low.

When a specific actuator 27 of the plurality of actuators is operated independently, the pressure in the load pressure detection oil passage 31 decreases by a set value on the secondary side of the pressure reducing valve 38, and the shuttle valve 33 is turned on. Through the regulator oil passage 34. Then, the reduced load pressure is led to the pump regulator 35, and the discharge pressure of the hydraulic pump 21 decreases. Therefore, the differential pressure between the discharge pressure of the hydraulic pump in the discharge line 22 and the load pressure of the actuator in the load pressure line 29 is reduced by the amount reduced by the pressure reducing valve 38. In this way, it is possible to reduce the differential pressure before and after the throttle 23 with respect to the specific actuator 27 and suppress power loss.

The present invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that the invention extends to the modified version.

[0013]

[Effect of device]

 As described in detail in the above one embodiment, the present invention reduces the differential pressure before and after the throttle by providing a pressure reducing valve in the load pressure detecting circuit of any actuator. You can Therefore, the power loss of the actuator is suppressed, which can contribute to the performance improvement of the load sensing hydraulic circuit.

[Brief description of drawings]

FIG. 1 is a load sensing hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 2 is a conventional load sensing hydraulic circuit diagram.

[Explanation of symbols]

 21 Hydraulic Pump 22 Discharge Pipeline 23, 24 Throttle 27, 28 Actuator 29, 30 Load Pressure Pipeline 31, 32 Load Pressure Detection Oil Passage 33 Shuttle Valve 35 Pump Regulator 38 Pressure Reduction Valve 40 Branch Oil Passage 41 Throttle 42 Tank

Claims (1)

[Scope of utility model registration request] 1. A load pressure detection oil passage is branched from a load pressure pipe of each actuator, and each load pressure detection oil passage is connected to an inlet side of a shuttle valve.
In the load sensing hydraulic circuit where the outlet side of the shuttle valve is connected to the pump regulator, a pressure reducing valve is installed in the load pressure detecting oil passage of any arbitrary actuator, and a branch oil passage is provided between the pressure reducing valve and the shuttle valve. The load sensing hydraulic circuit is characterized in that the branch oil passage is provided with a throttle and is connected to a tank.