Control device for working machine

Abstract

A control device for a working machine according to the present invention comprises a capacity variable pump for supplying working oil, a controller for controlling the discharge amount of the pump, a control valve for controlling the working oil discharged from the pump, a hydraulic actuator operated by the working oil from the control valve, an operating lever for operating the hydraulic actuator, and a relief valve to be operated when the pressure of the working oil is a relief pressure or more. The controller has a dynamic emulation model of a hydraulic driving device, and is constituted to estimate the pressure oil flow rate passing through the relief valve from the emulation model according to the operation amount of the operating lever, and to control the pump flow rate of the pump so that the relief flow rate estimation value gets close to zero. According to this, relief loss can be precisely reduced without generating a response delay or pressure loss, and the power can be saved.

Description

technical field [0001] The invention relates to an oil pressure control circuit of an oil pressure working machine. Background technique [0002] In the hydraulic circuit of the working machine, when a large load is applied to the hydraulic cylinder and other actuators, the pressure in the hydraulic circuit will increase. In order to protect the hydraulic device in the circuit, a relief valve is installed. Once the circuit pressure exceeds the relief pressure, the working oil will be released to the oil tank through the relief valve. Therefore, the pressure will not be too large, and damage to the hydraulic device can be prevented. [0003] However, much of the working oil supplied by the pump is directly released to the oil tank through the relief valve without being supplied to the actuator. Therefore, there is a problem that a large amount of pumping power is wasted as a relief valve loss, resulting in a decrease in energy efficiency. [0004] Therefore, cut-off contro...

AI Technical Summary

Problems solved by technology

[0006] However, the former has a problem in that since a throttle valve is provided downstream of the relief valve, a pressure loss occurs due to the throttle valve, and the energy efficiency of the system cannot be sufficiently improved.

[0007] The problem with the latter is that since there is a time lag from the generation of the overflow flow to the temperature rise of the relief valve, there is a time lag from the moment the overflow flow is generated to the time when the pump flow is cut off and controlled, so that a sufficient reduction in the overflow cannot be obtained. loss effect

In addition, after the overflow flow rate becomes 0, the pump flow rate is still controlled by cut-off due to residual heat detection, and the necessary driving force cannot be obtained immediately

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