Method for controlling a hydraulic cylinder in a work machine and control system for a work machine

Patent metadata

Field	Value
Publication number	US-9670944-B2
Application number	US-9791607-A
Country	US
Kind code	B2
Filing date	Jan 16, 2007
Priority date	Jan 16, 2006
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A method is provided for controlling a hydraulic cylinder in a work machine, which hydraulic cylinder is arranged to move an implement that is subjected to a load, with the hydraulic cylinder being controlled by a hydraulic machine. The method includes detecting that a lifting movement of the implement is to be initiated, and attaining a basic speed of the hydraulic machine before lifting takes place.

First claim

The invention claimed is:

1. A control system for a work machine comprising
a hydraulic machine and at least one hydraulic cylinder, wherein a first port of the hydraulic machine is connected to the hydraulic cylinder via a first line,
a line that connects the first port of the hydraulic machine and a tank,
an electric machine arranged to drive the hydraulic machine,
control means arranged in the line to drain the first port of the hydraulic machine, and
a control unit programmed to detect that a lifting movement of the implement is to be initiated and, after detecting that a lifting movement of the implement is to be initiated, before the lifting movement takes place by supplying fluid to the hydraulic cylinder, control the control means to provide a leakage flow from the hydraulic machine so that a basic speed of the hydraulic machine is attained,
wherein the hydraulic machine is connected to a piston side of the hydraulic cylinder via the first line and a piston-rod side of the hydraulic cylinder via a second line, the hydraulic machine has a second port which is connected to the piston-rod side of the hydraulic cylinder via the second line, and the hydraulic machine is arranged to be driven in two different directions, with one direction being associated with a flow out from the first port and the second direction being associated with a flow out from the second port.

2. The control system as claimed in claim 1 , wherein the control means comprises an electrically controlled valve.

3. The control system as claimed in claim 1 , wherein the control means comprises a continuously variable valve.

4. The control system as claimed in claim 1 , wherein the control system comprises a lifting lever for detection that a lifting movement of the implement is to be initiated.

5. The control system as claimed in claim 1 , wherein the system comprises a sensor for sensing pressure on the piston side of the hydraulic cylinder.

6. The control system as claimed in claim 1 , wherein the hydraulic cylinder is adapted to move an implement in order to perform a work function.

7. The control system as claimed in claim 6 , wherein the hydraulic cylinder comprises a lifting cylinder for moving a load arm which is pivotably connected to a vehicle frame, the implement being arranged on the load arm.

8. The control system as claimed in claim 6 , wherein the hydraulic cylinder comprises a tilting cylinder for moving the implement, which is pivotably connected to a load arm, which is in turn pivotably connected to a vehicle frame.

Assignees

• Vigholm Bo
• Palo Markku
• Volvo Constr Equip Ab

Inventors

• Vigholm Bo
• Palo Markku

Classifications

• F03C1/00

  Reciprocating-piston liquid engines · CPC title

• E02F9/2095

  Control of electric, electro-mechanical or mechanical equipment not otherwise provided for, e.g. ventilators, electro-driven fans (control of hydraulic driven equipment E02F9/22) · CPC title

• F15B11/0406

  during starting or stopping (F15B11/048 takes precedence) · CPC title

• F04B17/03

  driven by electric motors · CPC title

• F15B21/14 Primary

  Energy-recuperation means · CPC title