US 2014/0174071 A1 · HYDRAULIC CONTROL SYSTEM FOR CONSTRUCTION MACHINERY

Abstract

The present invention relates to a hydraulic control system for construction machinery capable of variably adjusting a set pressure of a relief valve, which controls a set pressure of a hydraulic system, according to a value inputted by means of pressure in the hydraulic system or the manipulation of a joystick. The hydraulic control system comprises: a flow control valve installed in a passage between a hydraulic pump and a hydraulic actuator, for controlling the driving of the hydraulic actuator by being switched by a control signal according to the manipulation of the joystick; a main relief valve installed in a passage between an upstream-side discharge passage of the hydraulic pump and a hydraulic tank, for returning a working fluid to the hydraulic tank when a high load exceeding a set pressure occurs in the system; a pressure controlling means for controlling, either continuously or in stages, a set pressure of the main relief valve; a pressure sensing means for sensing a pressure at a discharge side of the hydraulic pump; and a controller for determining the value inputted by the manipulation of the joystick, and a required set pressure for the relief valve according to the system pressure sensed by the pressure sensing means, and then outputting a control signal to the pressure controlling means to enable a set pressure of the relief valve to be variably adjusted to a determined set pressure.

Claims13

Dependent claims

A pressure control system for a construction machine, comprising:

a variable displacement hydraulic pump;
a plurality of hydraulic actuators connected to the hydraulic pump;
a plurality of joysticks configured to respectively output control signals according to manipulation amounts thereof;
a flow rate control valve installed in a flow path between the hydraulic pump and the hydraulic actuators and configured to be shifted to control the drive of the hydraulic actuators in response to a control signal according to an manipulation of each of the joysticks;
a main relief valve installed in a flow path between a discharge flow path on an upstream side of the hydraulic pump and a hydraulic tank and configured to return a hydraulic fluid to the hydraulic tank when a high load that exceeds a set pressure of the main relief valve occurs in the system;
a pressure adjustment means configured to adjust the set pressure of the main relief valve in a consecutive or stepwise manner;
a pressure detection means configured to detect a pressure of the hydraulic fluid on the discharge side of the hydraulic pump;
and
a controller configured to determine the set pressure of the relief valve, which is required according to an input value by the manipulation of the joystick and a system pressure that is detected by the pressure detection means and configured to output a control signal to the pressure adjustment means so as to enable the set pressure of the relief valve to be variably adjusted to the determined set pressure.

6 more elements

A pressure control system for a construction machine, including a variable displacement hydraulic pump, a hydraulic actuator connected to the hydraulic pump, a plurality of joysticks, a flow rate control valve configured to be shifted to control the drive of the actuator, a main relief valve configured to return a hydraulic fluid to a hydraulic tank when a high load that exceeds a set pressure of the main relief valve occurs in the system, a pressure adjustment means configured to adjust the set pressure of the main relief valve in a consecutive or stepwise manner, a pressure detection means configured to detect a pressure of the hydraulic fluid on the discharge side of the hydraulic pump, and a controller configured to control the set pressure of the relief valve to be adjusted based on an input value of a control signal by the manipulation of the joystick and a system pressure, the pressure control system comprising:

a first step of detecting the input value of the control signal by the manipulation of the joystick and the system pressure by the pressure detection means;
a second step of determining the set pressure of the relief valve based on the input value of the joystick and the system pressure, respectively, or determining the set pressure of the relief valve based on both the input value of the joystick and the system pressure;
a third step of determining a final set pressure of the relief valve among the set pressures of the relief valve determined in the second step;
and
a fifth step of outputting a control signal to the pressure adjustment means to control the pressure of the relief valve to be set to the final set pressure determined in the third step S300.

2 more elements

Dependencies are inferred from the claim text.

Hydraulic control system for construction machinery

Life of this patent

Hydraulic control system for construction machinery

Life of this patent

Abstract

Claims13