Hydraulic circuit for construction machinery having floating function and method for controlling floating function

Patent metadata

Field	Value
Publication number	US-10094092-B2
Application number	US-201314900495-A
Country	US
Kind code	B2
Filing date	Oct 31, 2013
Priority date	Jun 28, 2013
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A hydraulic circuit for construction machinery having a floating function, according to the present invention, is provided with: two or more hydraulic pumps; a hydraulic cylinder connected to the hydraulic pumps; a boom driving control valve provided on the flow path between the hydraulic pump on one side and the hydraulic cylinder; a boom confluence control valve provided on the flow path between the hydraulic pump on the other side and the hydraulic cylinder; an operating lever; a first sensor for measuring the hydraulic fluid pressure of a large chamber of the hydraulic cylinder; a second sensor for measuring the boom lowering pilot pressure applied to one end of the boom driving control valve; a control valve provided on the flow path between the operating lever and the other ends of the boom driving control valve and the boom confluence control valve.

First claim

The invention claimed is:

1. A hydraulic circuit for a construction machine having a floating function, comprising:
at least two hydraulic pumps;
a hydraulic cylinder driven by hydraulic fluids supplied from the hydraulic pumps;
a boom driving control valve installed in a flow path between any one of the hydraulic pumps and the hydraulic cylinder and configured to be shifted to control a start, a stop, and a direction change of the hydraulic cylinder;
a boom confluence control valve installed in a flow path between another of the hydraulic pumps and the hydraulic cylinder and configured to be shifted to allow the hydraulic fluids discharged from the hydraulic pumps to join together so as to be supplied to a large chamber of the hydraulic cylinder or to allow hydraulic fluids of the large chamber and a small chamber of the hydraulic cylinder to join together so as to be supplied to a hydraulic tank;
a manipulation lever (RCV) configured to output a manipulation signal corresponding to a manipulation amount;
a first pressure sensor configured to measure a pressure of the hydraulic fluid on the large chamber of the hydraulic cylinder;
a second pressure sensor configured to measure a boom-down pilot pressure that is applied to an end of the boom driving control valve; and
a control valve installed in a flow path between the manipulation lever and the boom driving control valve, and installed in another flow path between the manipulation lever and the boom confluence control valve, and configured to be shifted in response to the application of electrical signals that correspond to the pressure and the boom-down pilot pressure detected by the first and second pressure sensors to shift the boom confluence control valve to a floating state through application of the boom-down pilot pressure to the boom confluence control valve, or to supply the hydraulic fluid of the one of the hydraulic pumps to the small chamber of the hydraulic cylinder by the shift of the boom driving control valve through application of the boom-down pilot pressure to the boom driving control valve.

2. The hydraulic circuit according to claim 1 , wherein the control valve is a solenoid valve configured to be shifted to an initial state where the hydraulic fluid of the one of the hydraulic pumps is supplied to the small chamber of the hydraulic cylinder through the application of the boom-down pilot pressure to the boom driving control valve, or to an on state where the boom confluence control valve is shifted to the floating state through the application of the boom-down pilot pressure to the boom confluence control valve.

3. The hydraulic circuit according to claim 1 , wherein the control valve is shifted to an off state if the boom-down pilot pressure is higher than or equal to a predetermined pressure based on a detection signal of the second pressure sensor, and the hydraulic fluid pressure of the large chamber of the hydraulic cylinder is lower than or equal to another predetermined pressure based on a detection signal of the first pressure sensor.

4. A method for controlling a floating function for a construction machine including at least two hydraulic pumps, a hydraulic cylinder driven by hydraulic fluids supplied from the hydraulic pumps, a boom driving control valve installed in a flow path between any one of the hydraulic pumps and the hydraulic cylinder, a boom confluence control valve installed in a flow path between another of the hydraulic pumps and the hydraulic cylinder, a manipulation lever (RCV), a first pressure sensor configured to measure a pressure of the hydraulic fluid on a large chamber of the hydraulic cylinder, a second pressure sensor configured to measure a boom-down pilot pressure that is applied to an end of the boom driving control valve, and a control valve installed in a flow path between the manipulation lever and the boom driving control valve, and installed in another flow path between the manipulation lever the boom confluence control valve, the method comprising:
a step of determining whether a boom floating function switch is operated to be turned on;
a step of, if the boom floating function switch is operated to be turned on, shifting the control valve to an on state in response to the application of an electrical signal to the control valve to cause the boom confluence control valve to be shifted to a floating state through application of the boom-down pilot pressure to the boom confluence control valve;
a step of measuring the hydraulic fluid pressure of the large chamber of the hydraulic cylinder through the first pressure sensor, and measuring the boom-down pilot pressure that is applied to the end of the boom driving control valve through the second pressure sensor; and
a step of shifting the control valve to an off state if the boom-down pilot pressure is higher than or equal to a predetermined pressure based on a detection signal of the second pressure sensor, and the hydraulic fluid pressure of the large chamber of the hydraulic cylinder is lower than or equal to another predetermined pressure based on a detection signal of the first pressure sensor.

5. A hydraulic circuit for a construction machine having a floating function, comprising:
at least two hydraulic pumps;
a hydraulic cylinder driven by hydraulic fluids supplied from the hydraulic pumps;
a boom driving control valve installed in a flow path between any one of the hydraulic pumps and the hydraulic cylinder and configured to be shifted to control a start, a stop, and a direction change of the hydraulic cylinder;
a boom confluence control valve installed in a flow path between another of the hydraulic pumps and the hydraulic cylinder and configured to be shifted to allow the hydraulic fluids discharged from the hydraulic pumps to join together so as to be supplied to a large chamber of the hydraulic cylinder or to allow hydraulic fluids of the large chamber and a small chamber of the hydraulic cylinder to join together so as to be supplied to a hydraulic tank;
a manipulation lever (RCV) configured to output a manipulation signal corresponding to a manipulation amount;
a first pressure sensor configured to measure a pressure of the hydraulic fluid on the large chamber of the hydraulic cylinder;
a second pressure sensor configured to measure a boom-down pilot pressure that is applied to an end of the boom driving control valve;
a first electronic proportional control valve installed in a flow path between the manipulation lever and the boom confluence control valve and configured to shift the boom confluence control valve to a floating mode by generating the boom-down pilot pressure in proportion to an electrical signal applied thereto and applying the generated boom-down pilot pressure to the boom confluence control valve;
a second electronic proportional control valve installed in a flow path between the manipulation lever and the boom driving control valve and configured to supply the hydraulic fluid of the one of the hydraulic pumps to the small chamber of the hydraulic cylinder by generating the boom-down pilot pressure in proportion to the electrical signal applied thereto and applying the generated boom-down pilot pressure to the boom driving control valve; and
a controller configured to receive an input of the pressure values detected by the first and second pressure sensors, calculate the electrical signal corresponding to the pressure value detected by the second pressure sensor, and apply the calculated electrical signal to the first and second electronic proportional control valves.

6. A method for controlling a floating function for a construction machine including at least two hydraulic pumps, a hydraulic cylinder driven by hydraulic fluids supplied from the hydraulic pumps, a boom driving control valve i

Assignees

• Volvo Constr Equip Ab

Inventors

• Joung Hea-Gyoon
• Kim Sung-Gon

Classifications

• F15B2211/31582

  having multiple pressure sources and a single output member · CPC title

• F15B2211/665

  Methods of control using electronic components · CPC title

• F15B11/17

  using two or more pumps · CPC title

• F15B2211/20576

  with multiple pumps · CPC title

• F15B11/10

  in which the servomotor position is a function of the pressure {also pressure regulators as operating means for such systems, the device itself may be a position indicating system} · CPC title