Pressure overshooting prevention system for electronic hydraulic pump in hydraulic system

Abstract

The present disclosure relates to a pressure overshooting prevention system for an electronic hydraulic pump in a hydraulic system, in which a flow rate command is added (+), a discharge flow rate is subtracted (−), a displacement flow rate (Delta Q) is calculated, a first pressure command corresponding to the displacement flow rate (Delta Q) is generated, a working fluid pressure value corresponding to the discharge flow rate is generated, a limit pressure command is generated to limit an increasing gradient of the working fluid pressure value, a stall is determined based on a first rate of change of the flow rate command, and a second rate of change of the discharge flow rate, and the limit pressure command is set to a second pressure command when the stall is determined, and a small value of the first pressure command and the second pressure command is selected as a final pressure command so as to control an electronic proportional control valve, thereby reducing overshooting of the electronic hydraulic pump.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This Application is a Section 371 National Stage Application of International Application No. PCT / KR2012 / 011352, filed Dec. 24, 2012 and published, not in English, as WO 2013 / 100509 on Jul. 4, 2013.FIELD OF THE DISCLOSURE[0002]The present disclosure relates to a pressure overshooting prevention system for an electronic hydraulic pump in a hydraulic system, and more particularly, to a pressure overshooting prevention system for an electronic hydraulic pump in a hydraulic system, capable of preventing pressure overshooting by controlling a pressure command to an electronic hydraulic pump in a hydraulic system in a state in which an actuator cannot be operated any more.BACKGROUND OF THE DISCLOSURE[0003]In general, in a hydraulic system, a working fluid is discharged from an electronic hydraulic pump, and the working fluid is on standby at an inlet of a main control valve. A plurality of spools is provided in the main control valve, and a plur...

AI Technical Summary

Benefits of technology

The present disclosure provides a pressure overshooting prevention system for an electronic hydraulic pump in a hydraulic system. The system quickly reduces the discharge flow rate of the pump when a stall occurs, thus stabilizing the hydraulic system. It achieves this by more quickly changing the pressure command to control the pump, which results in a quicker movement of the swash plate angle. This in turn, reduces the overshooting working fluid flow rate and improves the durability of the hydraulic system.

Problems solved by technology

The piston rod may reach an end point at which the piston rod cannot be extended any more, or the piston rod cannot be extended or retracted any more due to large external loads.

In this situation, because a required flow rate is constantly required, the electronic hydraulic pump constantly discharges the working fluid to provide the working fluid to the actuator, and as a result, there is a risk that hydraulic pressure in the hydraulic system may be raised to a dangerous level.

However, in the aforementioned situation in which the actuator stalls, the working fluid is constantly discharged from the electronic hydraulic pump even in a case in which the hydraulic pressure is being stabilized while being decreased to safe pressure by opening the variable relief valve or adjusting the swash plate angle to a minimum level, and in this case, a pressure peak instantaneously occurs due to the flow rate of the discharged working fluid.

There is a problem in that the pressure peak weakens durability of the hydraulic system.

Accordingly, there is a problem in that the overshot working fluid degrades durability of the hydraulic system.

Images