Hydraulic system and method for controlling an implement of a working machine

Patent metadata

Field	Value
Publication number	US-10280948-B2
Application number	US-201415129837-A
Country	US
Kind code	B2
Filing date	Apr 4, 2014
Priority date	Apr 4, 2014
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A hydraulic system is provided for a working machine that includes a hydraulic cylinder for raising and lowering an implement. The hydraulic system includes a sensor for measuring a pressure in the hydraulic cylinder; and a control unit for controlling the movement of the hydraulic cylinder; wherein the control unit is configured to compare a pressure value measured by the sensor with a preset target pressure level range and to control the pressure in the hydraulic cylinder to be within the preset target pressure level range by adding or draining hydraulic fluid to/from a pressure side of the hydraulic cylinder for maintaining a substantially constant ground contact force between the implement and the ground.

First claim

The invention claimed is:

1. A hydraulic system for a working machine comprising a hydraulic cylinder for raising and lowering an implement, the hydraulic system comprising
a sensor for measuring a pressure in the hydraulic cylinder;
a control unit for controlling the movement of the hydraulic cylinder; and
a hydraulic accumulator unit arranged in fluid communication with a pressure side of the hydraulic cylinder and the sensor;
wherein the control unit is configured to compare a pressure value measured by the sensor with a preset target pressure level range and to control the pressure in the hydraulic cylinder to be within the preset target pressure level range by adding or draining hydraulic fluid to/from the pressure side of the hydraulic cylinder solely by receiving hydraulic fluid from the hydraulic accumulator unit or by, providing hydraulic fluid to the hydraulic accumulator unit for maintaining a substantially constant ground contact force between the implement and the ground.

2. The hydraulic system according to claim 1 , wherein the sensor is in fluid communication with the pressure side of the hydraulic cylinder and electrically connected to the control unit.

3. The hydraulic system according to claim 1 , wherein the pressure side of the hydraulic cylinder is a piston side of the hydraulic cylinder, wherein hydraulic fluid is added or drained to/from the piston side of the hydraulic cylinder for maintaining the substantial constant ground contact force between the implement and the ground.

4. The hydraulic system according to claim 3 , wherein the control unit is configured to control a control valve such that hydraulic fluid is drained from the piston side of the hydraulic cylinder if the measured pressure value is above the preset pressure level range.

5. The hydraulic system according to claim 3 , wherein a piston side sensor valve is arranged In fluid communication with the piston side of the hydraulic cylinder and the sensor.

6. The hydraulic system according to claim 5 , wherein the control unit, is configured to position the piston side sensor valve and a piston rod side drain valve in an open state when adding or draining hydraulic fluid to/from the piston side of the hydraulic cylinder, and wherein the piston rod side drain valve is arranged in fluid communication with the piston rod side of the hydraulic cylinder and a drain tank.

7. The hydraulic system according to claim 3 , wherein a piston rod side drain valve is arranged in fluid communication with the piston rod side of the hydraulic cylinder and a drain tank.

8. The hydraulic system according to claim 3 , wherein a piston rod side sensor valve is arranged in fluid communication with the piston rod side of the hydraulic cylinder and the sensor.

9. The hydraulic system according to claim 8 , wherein the control unit is configured to position the piston rod side sensor valve and a piston side drain valve in an open state when adding or draining hydraulic fluid to/from the piston rod side of the hydraulic cylinder, and wherein the piston side drain valve is arranged in fluid communication with the piston side of the hydraulic cylinder and a drain tank.

10. The hydraulic system according to claim 3 , wherein a piston side drain valve is arranged in fluid communication with the piston side of the hydraulic cylinder and a drain tank.

11. A hydraulic system for a working machine comprising a hydraulic cylinder for raising and lowering an implement, the hydraulic system comprising
a sensor for measuring a pressure in the hydraulic cylinder;
a control unit for controlling the movement of the hydraulic cylinder; and
a hydraulic accumulator unit arranged in fluid communication with a pressure side of the hydraulic cylinder and the sensor;
wherein the control unit is configured to compare a pressure value measured by the sensor with a preset target pressure level range and to control the pressure in the hydraulic cylinder to be within the preset target pressure level range by adding or draining hydraulic fluid to/from the pressure side of the hydraulic cylinder by receiving hydraulic fluid from the hydraulic accumulator unit or by providing hydraulic fluid to the hydraulic accumulator unit for maintaining a substantially constant ground contact force between the implement and the ground, wherein the pressure side of the hydraulic cylinder is a piston side of the hydraulic cylinder, wherein hydraulic fluid is added or drained to/from the piston side of the hydraulic cylinder for maintaining the substantial constant ground contact force between the implement and the ground, and wherein the control unit is configured to control a control valve such that a pump unit adds hydraulic fluid to the piston side of the hydraulic cylinder if the measured pressure value is below the preset pressure level range.

12. A hydraulic system for a working machine comprising a hydraulic cylinder for raising and lowering an implement, the hydraulic system comprising
a sensor for measuring a pressure in the hydraulic cylinder;
a control unit for controlling the movement of the hydraulic cylinder; and
a hydraulic accumulator unit arranged in fluid communication with a pressure side of the hydraulic cylinder and the sensor;
wherein the control unit is configured to compare a pressure value measured by the sensor with a preset target pressure level range and to control the pressure in the hydraulic cylinder to be within the preset target pressure level range by adding or draining hydraulic fluid to/from the pressure side of the hydraulic cylinder by receiving hydraulic fluid from the hydraulic accumulator unit or by providing hydraulic fluid to the hydraulic accumulator wilt for maintaining a substantially constant ground contact force between the implement and the ground, wherein the pressure side of the hydraulic cylinder is a piston rod side of the hydraulic cylinder, wherein hydraulic fluid is added or drained to/from the piston rod side of the hydraulic cylinder for maintaining the substantial constant ground contact force between the implement and the ground.

13. The hydraulic system according to claim 12 , wherein the control unit is configured to control a control valve such that a pump unit adds hydraulic fluid to the piston rod side of the hydraulic cylinder if the measured pressure value is below the preset pressure level range.

14. The hydraulic system according to claim 12 , wherein the control unit is configured to control a control valve such that hydraulic fluid is drained from the piston rod side of the hydraulic cylinder if the measured pressure value is above the preset pressure level range.

15. A control unit for controlling an implement of a working machine comprising a hydraulic cylinder for raising and lowering the implement, a sensor for measuring a pressure in the hydraulic cylinder, and a hydraulic accumulator unit arranged in fluid communication with a pressure side of the hydraulic cylinder and the sensor, wherein the control unit is configured to compare a pressure value measured by the sensor with a preset target pressure level range and to control the pressure in the hydraulic cylinder to be within the preset target pressure level range by adding or draining hydraulic fluid to/from a pressure side of the hydraulic cylinder solely by receiving hydraulic fluid from the hydraulic accumulator unit or by providing hydraulic fluid to the hydraulic accumulator unit for maintaining a substantially constant ground contact force between the implement and the pound.

16. A method for controlling an implement of a working machine comprising a hydr

Assignees

• Volvo Constr Equip Ab

Inventors

• Vigholm Bo
• Ekvall Andreas
• ÅBERG Linda

Classifications

• F15B2211/7128

  the chambers being connected in parallel · CPC title

• F15B2211/6658

  Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode · CPC title

• F15B2211/6313

  the pressure being a load pressure · CPC title

• F15B2211/625

  Accumulators · CPC title

• F15B2211/526

  electrically or electronically · CPC title