System for controlling hydraulic pump in construction machine

摘要

Disclosed is a system for controlling a hydraulic pump in a construction machine which can reduce the discharge flow of the hydraulic pump in proportion to the load pressure of the hydraulic pump to enhance operability by the driver. The present invention provides the system for controlling the hydraulic pump in the construction machine, which is characterized by detecting the discharge pressure of the hydraulic pump and the operation activity of an operation lever, and comparing the detected discharge pressure of the hydraulic pump and a predetermined pressure value, and when the detected discharge pressure exceeds the predetermined pressure value, the maximum dischargeable flow of the hydraulic pump is reduced in proportion to the difference between the detected pressure and the predetermined pressure value.

主权项

1. A hydraulic pump control system for a construction machine, comprising a variable displacement hydraulic pump, at least one hydraulic actuator connected to the hydraulic pump, a spool configured to control hydraulic fluid supplied to the actuator when the spool is shifted by a signal pressure that is supplied to the spool in proportion to a manipulation amount of a manipulation lever, a discharge pressure detection sensor installed in a discharge flow path of the hydraulic pump and configured to detect a discharge pressure of the hydraulic pump, a signal pressure detection sensor configured to detect the signal pressure based on the manipulation amount of the manipulation lever, and a control unit configured to control a discharge flow rate of the hydraulic pump in response to the discharge pressure detection sensor and a signal pressure detection signal from the detection sensors, the hydraulic pump control system comprising:
a first step of detecting the discharge pressure of the hydraulic pump and the manipulation amount of the operation lever by the discharge pressure detection sensor and the signal pressure detection sensor; a second step of calculating a flow rate required by the hydraulic pump based on the manipulation amount of the manipulation lever; a third step of comparing the sizes of the detected discharge pressure of the hydraulic pump and a preset pressure value; a fourth step of proportionally reducing, if the detected discharge pressure of the hydraulic pump is more than the preset pressure value, a maximum dischargeable flow rate of the hydraulic pump based on a difference between the detected discharge pressure and the preset pressure value, the maximum dischargeable flow rate of the hydraulic pump is reduced using a proportional control valve; a fifth step of comparing a currently required flow rate of the hydraulic pump with the maximum dischargeable flow rate of the hydraulic pump; and a sixth step of controlling the discharge flow rate of the hydraulic pump to be the maximum dischargeable flow rate if the currently required flow rate of the hydraulic pump exceeds the maximum dischargeable flow rate, while controlling the discharge flow rate of the hydraulic pump to be the flow rate required by the hydraulic pump, which is calculated based on the manipulation amount, if the currently required flow rate of the hydraulic pump is less than the maximum dischargeable flow rate; wherein if the detected discharge pressure is more than the preset pressure value even in the case where the discharge flow rate required by the hydraulic pump does not reach the maximum dischargeable flow rate in the sixth step, the discharge flow rate required by the hydraulic pump is proportionally reduced based on a difference between the detected discharge pressure and the preset pressure value in such a manner that the degree of reduction is proportionally controlled based on the size of the discharge flow rate so that the reduction rate of the discharge flow rate is controlled to be equal to, or to approximate the size of, the discharge flow rate required by the hydraulic pump.