Hydraulic system and a method for controlling a hydraulic system

Patent metadata

Field	Value
Publication number	US-9863449-B2
Application number	US-201114123122-A
Country	US
Kind code	B2
Filing date	May 31, 2011
Priority date	May 31, 2011
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A hydraulic system for a working machine includes a hydraulic actuator and a first hydraulic machine for supplying fluid to the hydraulic actuator. The hydraulic system further includes a hydraulic transformer for supplying fluid to the hydraulic actuator in parallel with the first hydraulic machine, and an accumulator for fluid. The hydraulic transformer includes a first port and a second port and the transformer is adapted to transform a first pressure and a first flow at the first port to a second pressure and a second flow at the second port. The second port of the hydraulic transformer is in fluid communication with the hydraulic actuator and the first port is in communication with the accumulator.

First claim

The invention claimed is:

1. A hydraulic system for a working machine, the hydraulic system comprising
a hydraulic actuator and a first hydraulic machine for supplying fluid to the hydraulic actuator,
a hydraulic transformer for supplying fluid to the hydraulic actuator in parallel with the first hydraulic machine, and an accumulator for fluid, the hydraulic transformer comprising a first port, a second port, and a third port and being adapted to transform a first pressure and a first flow at the first port to a second pressure and a second flow at the second port, the third port being in fluid communication with a tank, the second port of the hydraulic transformer being in fluid communication with the hydraulic actuator and the first port being in communication with the accumulator, and
a hydraulic actuator controller being adapted to determine a required hydraulic power for the hydraulic actuator, wherein the hydraulic actuator controller further is adapted to request a first power portion of the required hydraulic power from the hydraulic transformer and a second power portion of the required hydraulic power from the first hydraulic machine,
wherein the hydraulic system comprises a first conduit assembly, the first conduit assembly comprising one or more conduits and a main control valve connected to the actuator, and the first hydraulic machine is adapted to supply fluid to the hydraulic actuator via the first conduit assembly, the second port of the hydraulic transformer being in parallel with the first hydraulic machine in the first conduit assembly on a side of the main control valve opposite the actuator.

2. The hydraulic system according to claim 1 , wherein the system comprises a time delayer adapted to delay a response of the first hydraulic machine.

3. The hydraulic system according to claim 1 , wherein the system comprises a torque determiner, the torque determiner being adapted to determine a required torque signal for the first hydraulic machine in response to the required hydraulic power, the required torque signal including only frequencies which are below a cut-of frequency which is in the range of 1-10 Hz.

4. The hydraulic system according to claim 1 , wherein the system further comprises an accumulator pressure sensor adapted to determine a pressure in the accumulator, the hydraulic actuator controller being adapted to increase the pressure in the accumulator, by operating the first hydraulic machine, when the pressure in the accumulator is below a predetermined pressure value.

5. A work machine comprising a hydraulic system claim 1 .

6. The work machine according to claim 5 , wherein the work machine comprises an engine which is adapted to drive the first hydraulic machine.

7. A hydraulic system for a working machine, the hydraulic system comprising
a hydraulic actuator and a first hydraulic machine for supplying fluid to the hydraulic actuator,
a hydraulic transformer for supplying fluid to the hydraulic actuator in parallel with the first hydraulic machine, and an accumulator for fluid, the hydraulic transformer comprising a first port a second port, and a third port and being adapted to transform a first pressure and a first flow at the first port to a second pressure and a second flow at the second port, the third port being in fluid communication with a tank, the second port of the hydraulic transformer being in fluid communication with the hydraulic actuator and the first port being in communication with the accumulator, and
a hydraulic actuator controller being adapted to determine a required hydraulic power for the hydraulic actuator, wherein the hydraulic actuator controller further is adapted to request a first power portion of the required hydraulic power from the hydraulic transformer and a second power portion of the required hydraulic power from the first hydraulic machine,
wherein the hydraulic actuator controller is adapted to determine a required hydraulic power signal and to convert the required hydraulic power signal into a high frequency power signal and a low frequency power signal.

8. The hydraulic system according to claim 7 , wherein the hydraulic actuator controller comprises a hydraulic signal filter.

9. The hydraulic system according to claim 7 , wherein the hydraulic actuator controller is adapted to determine a required hydraulic power electronic signal, the hydraulic actuator controller further comprises an electronic filter.

10. The hydraulic system according to claim 7 , wherein the high frequency power signal includes a portion of the required hydraulic power signal which contains frequencies of the required hydraulic power signal which are equal to or above a cut-of frequency which is in the range of 1-10 Hz, and the low frequency power signal includes a portion of the required hydraulic power signal which includes frequencies of the required hydraulic power signal which are below the cut-of frequency.

11. A method for controlling a hydraulic system, the hydraulic system comprising a hydraulic actuator and a first hydraulic machine for supplying hydraulic fluid to the hydraulic actuator, and a hydraulic transformer for supplying fluid to the hydraulic actuator in parallel with the first hydraulic machine, and an accumulator for fluid, the hydraulic transformer comprising a first port, a second port, and a third port and being adapted to transform a first pressure and a first flow at the first port to a second pressure and a second flow at the second port, the third port being in fluid communication with a tank, the second port of the hydraulic transformer being in fluid communication with the hydraulic actuator and the first port being in fluid communication with the accumulator, and a hydraulic actuator controller for determining a required hydraulic power for the hydraulic actuator, the hydraulic system comprising a first conduit assembly, the first conduit assembly comprising one or more conduits and a main control valve connected to the actuator, and the first hydraulic machine being adapted to supply fluid to the hydraulic actuator via the first conduit assembly, the second port of the hydraulic transformer being in parallel with the first hydraulic machine in the first conduit assembly on a side of the main control valve opposite the actuator, the method comprising:
determining a required hydraulic power for the hydraulic actuator using the hydraulic actuator controller,
requesting a first power portion of the required hydraulic power from the hydraulic transformer,
requesting a second power portion of the required hydraulic power from the first hydraulic machine, and
supplying fluid to the hydraulic actuator via the hydraulic transformer, the first hydraulic machine, and the first conduit assembly.

12. The method according to claim 11 , wherein the method comprises:
delaying the request of the second power portion for a predetermined delay time.

13. The method according to claim 11 , wherein the first hydraulic machine is adapted to be driven by an engine, the engine being adapted to impart a torque on the first hydraulic machine, the method comprising:
determining a requested torque from the engine, and
issuing a signal to the engine such that the requested torque is obtained.

14. The method according to claim 11 , wherein the method further comprising:
determining a pressure in the accumulator;
if the pressure in the accumulator is below a predetermined pressure value, operating the first hydraulic machine such that the pressure in the accumulator increases.

15. A method for controlling a hydraulic system, the hydraulic system comprising a hydraul

Assignees

• Heybroek Kim
• Wiktor Roland
• Volvo Constr Equip Ab

Inventors

• Heybroek Kim
• Wiktor Roland

Classifications

• E02F9/2242

  including an electronic controller · CPC title

• F15B2211/625

  Accumulators · CPC title

• E02F9/2235

  including an electronic controller · CPC title

• F15B2211/26

  Power control functions · CPC title

• F15B2211/6313

  the pressure being a load pressure · CPC title