FLUID-WORKING MACHINE AND METHOD OF OPERATING A FLUID-WORKING MACHINE

• US 20120059523A1
• Filed: 02/23/2011
• Published: 03/08/2012
• Est. Priority Date: 02/23/2010
• Status: Active Grant

• Current Assignee: Artemis Intelligent Power Ltd. (Danfoss A/S)
• Original Assignee: Artemis Intelligent Power Ltd. (Danfoss A/S)
• Inventors: Salter, Stephen Hugh, Rampen, William Hugh Salvin, Fielding, Michael Richard, Caldwell, Niall James, Laird, Stephen Michael, Joly, Pierre Robert
• Granted Patent: US 9,739,266 B2
• Time in Patent Office: Days
• US Class Current: 700/281
• CPC Class Codes: F03B 15/02 by varying liquid flow
• CPC Class Codes: F03D 9/25 the apparatus being an electrical generator F03D9/22 takes precedence
• CPC Class Codes: F05B 2260/406 through hydraulic systems
• CPC Class Codes: Y02E 10/20 Hydro energy
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

The present invention relates to a method of operating a fluid-working machine wherein the volume of working fluid displaced each cycle is selectable and wherein the volume of working fluid displaced by a first working chamber takes into account the suitability of the working chamber to displace fluid. The invention extends in further aspects to power absorbing structures such as renewable energy devices comprising such fluid working machines. The invention allows the operation of fluid working machines and power absorbing structures which are more long lived.

Claims

1. A method of operating a fluid-working machine comprising a plurality of working chambers of cyclically varying volume, each said working chamber operable to displace a volume of working fluid which is selectable for each cycle of working chamber volume, the method comprising selecting the volume of working fluid displaced by one or more said working chambers during each cycle of working chamber volume to carry out a working function responsive to a received demand signal, characterised by selecting the volume of working fluid displaced by a first working chamber during a cycle of working chamber volume taking into account the suitability of said first working chamber to displace fluid to carry out the working function.

2. A method of operating a fluid-working machine according to claim 1, the fluid-working machine comprising a controller, and at least one valve associated with each working chamber operable to regulate the connection of the respective working chamber to a low pressure manifold and a high pressure manifold, at least one valve associated with each working chamber being electronically controllable under the active control of the controller to select the volume of working fluid displaced during a cycle of working chamber volume, wherein the controller receives the demand signal and actively controls the said electronically controllable valves, in phased relationship to cycles of working chamber volume, to select the displacement of fluid by one or more of the working chambers on each cycle of working chamber volume, responsive to the received demand signal.

3. A method of operating a fluid-working machine according to claim 1 wherein the amount of fluid displaced by the first working chamber during an individual cycle of working chamber volume is greater when it is suitable than when it is unsuitable.

4. A method of operating a fluid-working machine according to claim 1 comprising also taking into account the relative suitability of at least one second working chamber to displace fluid to carry out the working function.

5. A method of operating a fluid-working machine according to claim 4, wherein the amount of fluid displaced by the first working chamber during an individual cycle of working chamber volume is greater than would be the case if a second said working chamber was relatively more suitable than the first working chamber.

6. A method of operating a fluid-working machine according to claim 4, wherein each working chamber is operable on each cycle of working chamber volume to carry out an active cycle in which the chamber makes a net displacement of working fluid or an idle cycle in which the chamber makes substantially no net displacement of working fluid, wherein, on at least some occasions, the first working chamber carries out an active cycle instead of an idle cycle as a result of the unsuitability of the second working chamber

7. A method of operating a fluid-working machine according to claim 4, wherein each working chamber is operable on each cycle of working chamber volume to carry out an active cycle in which the chamber makes a net displacement of working fluid or an idle cycle in which the chamber makes substantially no net displacement of working fluid, wherein, on at least some occasions, the first working chamber carries out an active cycle instead of an idle cycle as a result of having greater suitability than the second working chamber.

8. A method of operating a fluid-working machine according to claim 4, wherein the volume of working fluid displaced by said at least one second working chambers is selected to carry out the working function responsive to the received demand signal, taking into account the selected volume of working fluid displaced by said first working chamber.

9. A method of operating a fluid-working machine according to claim 4, wherein volume cycles of the first working chamber are phased earlier or later than volume cycles of the second working chamber.

10. A method of operating a fluid-working machine according to claim 1, wherein suitability is determined by the historical amount of use of the one or more working chambers.

11. A method of operating a fluid-working machine according to claim 1, wherein suitability is determined by measurement or prediction of the net force applied to a rotatable shaft of said fluid working machine by fluid-pressurised working chambers.

12. A method of operating a fluid-working machine according to claim 1, comprising measuring or predicting the motion of a mechanical component, said motion being influenced by said fluid working machine, and determining the suitability of each working chamber responsive thereto.

13. A method of operating a fluid-working machine according to claim 1 wherein, when the demand indicated by the received demand signal is sufficiently low, the selected volume of fluid displaced by at least one of the working chambers which are available to carry out the working function is substantially zero for at least some cycles of working chamber volume.

16. Computer program code which, when executed on a fluid working machine controller, operates the fluid working machine according to claim 1.

14. A method of operating a fluid-working machine for a plurality of cycles, the fluid-working machine comprising a plurality of working chambers of cyclically variable volume, each said working chamber being operable to displace a selectable volume of working fluid during each cycle, and the method comprising:

controlling the plurality of working chambers in aggregate so as to cause the total volume of working fluid displaced during each cycle to conform to a global demand function; and

controlling the plurality of working chambers individually in accordance with a suitability function that determines the suitability of each working chamber.

15. A fluid-working machine comprising a controller and a plurality of working chambers of cyclically varying volume, each said working chamber operable to displace a volume of working fluid which is selectable by the controller on each cycle of working chamber volume, the controller operable to select the volume of working fluid displaced by one or more said working chambers on each cycle of working chamber volume to carry out a working function responsive to a received demand signal, characterised by the controller being operable to select the volume of working fluid displaced by a first working chamber on a cycle of working chamber volume taking into account the suitability of said first working chamber to displace fluid to carry out the working function.

17. A power absorbing structure comprising at least one mechanical component and further comprising a fluid working machine itself comprising a plurality of working chambers of cyclically varying volume, each said working chamber operable to displace a volume of working fluid which is selectable for each cycle of working chamber volume, the method comprising selecting the volume of working fluid displaced by one or more said working chambers during each cycle of working chamber volume to carry out a working function responsive to a received demand signal, the method further including measuring or predicting the motion of the mechanical component and selecting the volume of working fluid displaced by a first working chamber during a cycle of working chamber volume taking into account the measured or predicted motion of the mechanical component under influence of the working function.