DIGITAL HYDRAULIC PUMP/MOTOR TORQUE MODULATION SYSTEM AND APPARATUS

• US 20090317266A1
• Filed: 07/27/2007
• Published: 12/24/2009
• Est. Priority Date: 07/27/2006
• Status: Active Grant

• Current Assignee: Artemis Intelligent Power Ltd. (Danfoss A/S)
• Original Assignee: Artemis Intelligent Power Ltd. (Danfoss A/S)
• Inventors: Stein, Uwe Bernhard Pascal, Fielding, Michael Richard, Rampen, William Hugh Salvin, Caldwell, Niall James
• Granted Patent: US 8,348,627 B2
• Time in Patent Office: Days
• US Class Current: 417/53
• CPC Class Codes: F03C 1/0447 Controlling
• CPC Class Codes: F04B 1/06 Control
• CPC Class Codes: F04B 2201/1202 Torque on the axis
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 49/243 by keeping open the inlet valve
• CPC Class Codes: F04B 7/0076 the members being actuated by electro-magnetic means

Abstract

The present invention provides a hydraulic pump for use in driving a load with a control modulation system which modulates a primary control signal in order to accommodate variations in secondary changeable parameters which require control at a higher frequency or have a lower latency.

Claims

1. A method of controlling a fluid working machine having:

one or more working chambers of cyclically varying volume;

one or more inlet valves;

one or more outlet valves;

a rotating shaft driven by or driving a load; and

a controller for receiving data on a first changeable parameter and controlling the operating and closing sequence of said valves to selectively enable said working chamber separately on each of the expansion and contraction strokes of said chamber, so as to supply or accept fluid in accordance with said first change able parameter,

the method comprising the steps of;

monitoring a second changeable parameter requiring control at a higher frequency or having a lower latency than said first changeable parameter; and

modifying the valve actuation to supply or accept fluid demand in accordance with a combination of said first and said second changeable parameter.

2. A met hod as claimed in claim 1 wherein said first changeable parameter is controlled on a stroke-by-stroke basis.

3. A method as claimed in claim 1 wherein said second changeable parameter is controlled at a speed greater than a stroke-by-stroke basis.

4. A method as claimed in claim 1 in which said control according to said second changeable parameter is effected so as to adjust the torque applied to an output from said fluid working machine 10.

5. A method as claimed in claim 1 in which said control according to said second changeable parameter is effected so as to adjust the flow rate of fluid intake or output of said fluid working machine.

6. A method as claimed in claim 1 in which the response to the second changeable parameters is altering the opening or closing of said inlet or outlet valves over a sequence determined as being necessary to control the first changeable parameters so as to lengthen, shorten or segment the time the working chamber is connected to said LP manifold.

7. A method as claimed in claim 1 in which the response to the second changeable parameters is altering the opening or closing of said inlet or outlet valves over a sequence determined as being necessary to control the first changeable parameters so as to lengthen, shorten or segment the time the working chamber is connected to said HP manifold.

8. A method as claimed in claim 6 where the sequence alteration is effected by altering a signal given to the valves 12, 24 in one or more of the following ways:

delaying in time a signal to close the HPV so as to close the HPV later but still before BDC and thereby intake a larger volume of fluid from the high pressure manifold;

delaying in time a signal to close the HPV so as to close the HPV shortly after BDC so as to prevent decompression of the working chamber so as to prevent opening of the LPV so as to cause the inducted fluid from the high pressure manifold to be returned to said manifold;

advancing in time a signal to close the HPV so that the HPV closes after the beginning fluid intake from the high pressure manifold but before it was intended to close by the sequence-generating controller and thereby intake a smaller volume of fluid from the high pressure manifold;

deleting a signal to open the HPV so that no fluid is inducted from the high pressure manifold;

adding a signal to close the LPV where such a signal was not already commanded so as to insert an additional pumping cycle into the sequence and pump fluid to the high pressure manifold;

deleting a signal to close the LPV so as to remove a pumping cycle or motoring cycle from the sequence;

advancing in time a signal to close the LPV so as to pump a larger fraction of the working chamber volume to the high pressure manifold;

delaying in time a signal to close the LPV so as to pump a smaller fraction of the working chamber volume to the high pressure manifold; and

delaying in time a signal to close the HPV so as to cause a quantity of fluid from the HP manifold to be returned to the working chamber.

9. A method as claimed in claim 1 and including the step of communicating the sequence alteration or the effect of the sequence alteration on hydraulic flow or shaft torque to an external device.

10. A method as claimed in claim 9 and including the step of modifying the operation of said external device in accordance with the communicated sequence alteration.

11. A method as claimed in claim 1 including the step of predicting the demand to be supplied by said fluid working machine and initiating modulation in advance of a predicted need for said modulation.

12. A method as claimed in claim 1 including the step of monitoring a second changeable parameter associated with control of wheel or track slippage of a vehicle or controlling the intended trajectory associated with a vehicle.

13. A method as claimed in claim 12 wherein said second changeable parameter is one or more of:

steering wheel angle;

yaw rate;

acceleration;

wheel velocity;

wheel angular acceleration;

wheel slip;

vehicle lateral acceleration;

vehicle velocity and brake line pressure.

14. A method as claimed in claim 12 wherein said second changeable parameter includes one or more of:

vehicle roll rate and acceleration;

vehicle pitch rate and acceleration;

braking force applied at each wheel;

tyre air pressure;

vehicle acceleration and deceleration;

payload mass and distribution thereof.

15. A method as claimed in claim 1 including the step of monitoring a second changeable parameter associated with a generator drive system.

16. A method as claimed in claim 15 including the step of monitoring a changeable parameter comprising one or more of:

power factor, frequency, current or voltage harmonic frequency content.

17. A method as claimed in claim 1 including the step of monitoring a second changeable parameter associated with vibration of the load.

18. A method as claimed in claim 17 wherein said energy recovery apparatus comprises a fluid turbine and said second changeable parameter is selected from one or more of:

position, velocity or acceleration of a point on the turbine;

shaft torque;

blade pitch;

blade velocity; and

fluid velocity.

19. A fluid working machine having:

one or more working chambers of cyclically varying volume;

one or more inlet valves;

one or more outlet valves;

a rotating shaft driven by or driving a load;

a controller, for receiving data on a first changeable parameter and controlling the opening and closing sequence of said valves able to selectively enable said individual working chambers separately on each of the expansion and contraction strokes of said chambers, so as to supply or accept fluid in accordance with said first changeable parameter, a monitor, for monitoring a second changeable parameter requiring control at a higher frequency or having a lower latency than said first changeable parameter;

wherein said controller monitors said second changeable parameter and modifies the valve actuation to supply or accept fluid demand in accordance with a combination of said first and said second changeable parameter.

20. A fluid working machine as claimed in claim 20 and including a summing device 96 for combining said first and second changeable parameters by arithmetic summing thereof and for creating a demand signal associated with said combined demand.

21. A fluid working machine as claimed in claim 20 and including a selection device 96 for combining said first and second changeable parameters by selecting one or other to become a complete demand.

22. A fluid working machine as claimed in claim 20 and including one or more monitors 90 for monitoring one or more second changeable parameters, a modulation planner 92 for planning a demand based on the received data on one or more of said one or more second controllable parameters and a sequence modulator 96 for sequencing the demand to said pump 10 in accordance with a combination of demand associated with said first and second controllable parameters.

23. A fluid working machine as claimed in claim 20 and further including multiple fluid working machines 10, each being linked to the other and the supply of pressurised fluid 60 such as to allow fluid pumped from one machine to be passed to the supply of another machine.

24. A fluid working machine as claimed in claim 20 in which said controller 32 comprises an individual controller 120 for monitoring both of said first and said second controllable parameters.

25. A fluid working machine as claimed in claim 20 wherein said source of pressurised fluid 60 comprises a further fluid working machine 10.

26. A fluid working machine as claimed in claim 20 and including a predictor 70 for predicting the sequence alteration in advance of actual demand therefore and for causing the actuation of said valves to commence fluid supply control in advance of actual demand.

27. A Fluid working machine as claimed in claim 20 and including one or more sensors for sensing one or more secondary parameters.

28. A fluid working machine as claimed in claim 28 wherein said secondary sensors are sensors for monitoring one or more secondary parameters associated with the control of wheel or track slippage of a vehicle or vehicle trajectory.

30. A fluid working machine as claimed in claim 28 wherein said secondary sensors are sensors for detecting one or more of:

vehicle roll rate and acceleration;

vehicle pitch rate and acceleration;

braking force applied at each wheel;

tyre air pressure;

vehicle acceleration and deceleration;

payload mass and distribution thereof.

31. A fluid working machine as claimed in claim 28 wherein said secondary sensors are sensors for detecting one or more of:

power factor current and voltage harmonic content frequency.

32. A fluid working machine as claimed in claim 28 wherein said secondary sensors are sensors for detecting vibration of a load.

29. A fluid working machine as claimed in claim 29 in which said sensors comprise sensors for detecting one or more of:

steering wheel angle;

yaw rate;

acceleration;

wheel velocity;

wheel angular acceleration;

wheel slip;

vehicle lateral acceleration;

vehicle velocity and brake line pressure.

33. A method as claimed in claim 33 wherein said load comprises a fluid turbine and said secondary sensors are sensors for detecting one or more of:

position, velocity or acceleration of a point on the turbine;

shaft torque;

blade pitch;

blade velocity; and

fluid velocity.