Independent displacement opposing pump/motors and method of operation

• US 20060021813A1
• Filed: 09/22/2005
• Published: 02/02/2006
• Est. Priority Date: 01/10/2000
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The United States Environmental Protection Agency
• Original Assignee: GOV of The USA As REP By The ADMN of The US Environmental Protection Agency
• Inventors: Gray, Charles L. Jr.
• Granted Patent: US 8,177,009 B2
• Time in Patent Office: Days
• US Class Current: 180/165
• CPC Class Codes: B60K 17/10 of fluid gearing of fluid clutches B60K17/02
• CPC Class Codes: B60K 26/02 of initiating means or elements
• CPC Class Codes: B60K 6/12 by means of a chargeable fluidic accumulator
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: F03C 1/0642 inclined on main shaft axis
• CPC Class Codes: F04B 1/24 inclined to the main shaft axis
• CPC Class Codes: F04B 1/328 by changing the inclination of the axis of the cylinder barrel relative to the swash plate
• CPC Class Codes: F04B 23/06 the pumps being all of reciprocating positive-displacement type
• CPC Class Codes: F16H 2200/0034 the gear ratios comprising two forward speeds
• CPC Class Codes: F16H 61/42 involving adjustment of a pump or motor with adjustable output or capacity F16H61/46 takes precedence
• CPC Class Codes: F16H 61/423 Motor capacity control by fluid pressure control means
• CPC Class Codes: F16H 61/44 with more than one pump or motor in operation
• CPC Class Codes: F16H 61/448 Control circuits for tandem pumps or motors
• CPC Class Codes: F16H 61/452 Selectively controlling multiple pumps or motors, e.g. switching between series or parallel
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A hydraulic machine includes first and second opposing motors. Displacement of the first and second motors is controlled such that while the sum of the displacements of the first and second motors is below a threshold, the displacement of the first motor is substantially equal to the sum, and the displacement of the second motor is substantially equal to zero. While the sum of the displacements is above the threshold, the displacement of the first motor may be substantially equal to the displacement of the second motor, either as a displacement percentage or as a displacement volume. The first motor may be equal in capacity, or smaller than the second motor.

Claims

1. A hydraulic machine comprising:

a first variable displacement hydraulic motor having a first displacement capacity and a first output to which the first motor is configured to apply a varying degree of torque according to a degree of displacement of the first motor;

a second variable displacement hydraulic motor having a second displacement capacity, and a second output to which the second motor is configured to apply a varying degree of torque according to a degree of displacement of the second motor;

an output shaft to which the outputs of the first and second motors are rigidly coupled at respective ends thereof such that the first and second outputs rotate at a common rate; and

a displacement control unit configured to control displacement of the first and second motors such that while the sum of the displacements of the first and second motors is below a first value, the displacement of the first motor is substantially equal to the sum, and the displacement of the second motor is substantially equal to zero.

2. The machine of claim 1 wherein the control unit is further configured to control displacement of the first and second motors such that while the sum of the displacements of the first and second motors is above the first value, a displacement percentage of the first motor is substantially equal to a displacement percentage of the second motor.

3. The machine of claim 1 wherein the first value is equal to about 50% of a sum of the displacement capacities of the first and second motors.

4. The machine of claim 1 wherein the first value is equal to about 38% of a sum of the displacement capacities of the first and second motors.

5. The machine of claim 1 wherein the first value falls in a range between about 20% and 60% of a sum of the displacement capacities of the first and second motors.

6. The machine of claim 1 wherein the control unit is further configured to control displacement of the first and second motors such that if the sum of the displacements increases to beyond a second value, greater than the first value, a displacement percentage of the first motor is substantially equal to a displacement percentage of the second motor while the sum of the displacements of the first and second motors remains above the first value, and if the sum of the displacements decreases to below the first value, the displacement of the first motor is substantially equal to the sum, and the displacement of the second motor is substantially equal to zero while the sum of the displacements remains below the second value.

7. The machine of claim 1 wherein the control unit is further configured to control displacement of the first and second motors such that if the sum of the displacements increases to beyond the first value, a displacement percentage of the first motor is substantially equal to a displacement percentage of the second motor for at least a selected time period, regardless of subsequent changes of the sum of the displacements.

8. The machine of claim 1 wherein the first displacement capacity is substantially equal to the second displacement capacity.

9. The machine of claim 1 wherein the first displacement capacity is less than the second displacement capacity.

10. The machine of claim 9 wherein the first displacement capacity is equal to approximately 60% of the second displacement capacity.

11. The machine of claim 1 wherein the first displacement capacity is approximately equal to half the second displacement capacity.

12. The machine of claim 1, further comprising a drive gear positioned on the output shaft.

13. The machine of claim 1, further comprising bearing means for receiving unequal axial loads on the output shaft from the first motor and second motors.

14. The machine of claim 1 wherein the control unit is further configured to control displacement of the first and second motors such that while the sum of the displacements is greater than the first value and less than a second value, the displacement of the second motor is substantially equal to the sum, and the displacement of the first motor is substantially equal to zero.

15. The machine of claim 14 wherein the control unit is further configured to control displacement of the first and second motors such that while the sum of the displacements is greater than the second value a displacement percentage of the first motor is substantially equal to a displacement percentage of the second motor.

16. A hybrid vehicle system comprising:

a drive machine having first and second opposing and rotationally coupled motors; and

controlling means for independently controlling output torque of the first and second motors according to an operating range in which a total output torque of the machine falls.

17. The system of claim 16 wherein the controlling means comprises means for controlling the output torque of the first motor to be equal to the total output torque of the machine while the total lies in a first range of operation.

18. The system of claim 17 wherein the controlling means comprises means for controlling the output torque of the first motor to be equal to the output torque of the second motor while the total output torque lies in a second range of operation.

19. The system of claim 17 wherein the controlling means comprises means for controlling an output torque percentage of the first motor to be equal to an output torque percentage of the second motor while the total output torque lies in a second range of operation.

20. The system of claim 16, further comprising a vehicle drive train coupled to an output shaft of the drive machine.

21. The system of claim 16 wherein the first motor has an output torque capacity that is less than an output torque capacity of the second machine.

22. The system of claim 16 wherein the first motor has an output torque capacity of approximately 60% an output torque capacity of the second machine.

23. The system of claim 16 wherein the first motor has an output torque capacity approximately equal to an output torque capacity of the second machine.

24. The system of claim 16 wherein the first and second motors are hydraulic motors.

25. The system of claim 16 wherein the first and second motors are electric motors.

26. A method comprising:

varying an output torque of a first motor of a machine within a first range of a total output torque of the machine; and

maintaining a second motor of the machine, opposing the first motor, at an output torque of zero while varying the output torque of the first motor within the first range.

27. The method of claim 26, further comprising varying the output torques of the first and second hydraulic motors equally within a second range of total output torque.

28. The method of claim 27 wherein the varying the output torques of the first and second hydraulic motors equally comprises varying output torque percentages of the first and second hydraulic motors equally.

29. The method of claim 28 wherein an output torque capacity of the first motor is less than an output torque capacity of the second motor.

30. The method of claim 26, further comprising stroking the first and second motors to equal values when the total output torque of the machine increases to beyond a first selected threshold, and stroking the second motor to an output torque of zero while varying the output torque of the first motor when the total output torque decreases to below a second threshold, lower than the first threshold.