Flow rate control device for variable displacement type hydraulic pump for construction equipment

Abstract

The present invention pertains to a hydraulic pressure control device of a variable displacement type hydraulic pump for construction equipment, wherein operable sections of operation systems are formed in a wide manner while the hydraulic pump discharges a relatively small flow rate compared with the operation amount of the respective operation systems in the case of complex operations, so as to improve the pressure loss and the fuel ratio of the hydraulic pump. The device includes a flow rate controller, which is preferably connected to an operation amount detecting means and a swash plate control device, and receives operation signals from the operation system of a control device that are detected by the operation amount detecting means so as to control the discharge flow rate of the hydraulic pump. In the case of the complex operations, the flow rate controller pre-determines the required flow rate of an actuator for the respective operation systems via the operation signals of the operation systems and subsequently operates the square root of the sum of the squares of the respective required flow rates so as to determine the discharge flow rate of the hydraulic pump, thereby controlling the swash plate control device.

1 . A flow rate control apparatus of a variable displacement hydraulic pump for a construction machine comprising:
 an engine;   at least one variable displacement hydraulic pump having a swash plate control device for controlling an opening area thereof and configured to be pumped by the engine to provide hydraulic pressure;   a plurality of actuators for work apparatuses including a boom actuator or an arm actuator, a bucket actuator, and a swing motor;   a work apparatus control valve connected and installed between the hydraulic pump and the actuators for work apparatuses, and configured to control the hydraulic pressure discharged from the hydraulic pump to perform a start, a stop, and a swing operation of the actuators for the work apparatuses and the swing motor during the spool shift;   a manipulation amount detection means configured to detect a manipulation amount of a manipulation device to drive the actuators for work apparatuses; and   a flow rate controller connected to the manipulation amount detection means and the swash plate control device, and configured to receive a work apparatus manipulation signal of the manipulation device, which is detected by the manipulation amount detection means and to control a discharge flow rate of the hydraulic pump,   wherein the flow rate controller pre-determines the required flow rates of the respective actuators for work apparatuses through the work apparatus manipulation signal during a combined operation, and then controls the swash plate control device by calculating the square root of the sum of squares of the respective required flow rates to determine the discharge flow rate of the hydraulic pump.   
     
     
         2 . The flow rate control apparatus of a variable displacement hydraulic pump according to  claim 1 , wherein the manipulation amount detection means is constructed as a pilot pressure detection sensor. 
     
     
         3 . The flow rate control apparatus of a variable displacement hydraulic pump according to  claim 1 , wherein the swash plate control device is constructed as an electro proportional pressure reducing valve.