A power transfer system for a vehicle that comprises a an internal combustion engine, one or more drive wheels, and power transfer apparatus transfers power from the prime mover to the wheels for propelling the vehicle. The system further comprises an auxiliary hydraulic pump that has a drive shaft that coupled to a power take-off unit driven by engine, and to an auxiliary hydraulic motor powered by hydraulic fluid supplied from a hydraulic energy storage device such as an accumulator. As a result, the auxiliary hydraulic pump can be powered by hydraulic fluid from the accumulator when the prime mover is not operating, or by the prime mover when operating. A tandem arrangement of one way clutches can be employed to avoid the need to disconnect the auxiliary hydraulic pump from the prime mover during operation of the auxiliary hydraulic motor, and vice versa.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic illustration of an exemplary vehicle drive system including a power drive unit according to the invention.
Claims
1. A vehicle comprising a prime mover, one or more drive wheels, and a power transfer apparatus for transferring power from the prime mover to the wheels for propelling the vehicle, the power transfer apparatus including a power input shaft connected to the prime mover, a primary hydraulic pump, a hydraulic drive motor, a pump coupling for coupling the primary hydraulic pump to the power input shaft, a motor coupling for coupling the hydraulic drive motor to an output drive shaft for driving the one or more drive wheels, an energy storage device in which energy can be stored, primary hydraulic pump power circuitry for supplying pressurized hydraulic fluid from the primary hydraulic pump to the energy storage device, and hydraulic motor power circuitry for transferring pressurized hydraulic fluid from the energy storage device to the hydraulic drive motor; an auxiliary hydraulic pump for supplying hydraulic fluid to an auxiliary hydraulic system of the vehicle other than one that effects vehicle propulsion; a power take-off device driven by the power input shaft and drivingly connected to a drive shaft of the auxiliary hydraulic pump; and an auxiliary hydraulic motor powered by pressurized hydraulic fluid from the energy storage device and drivingly connected to the drive shaft of the auxiliary hydraulic pump for driving the drive shaft of the auxiliary hydraulic pump when not driven by the power take-off device.
2. A vehicle as set forth in claim 1, wherein the hydraulic drive motor is reversely operable as a hydraulic pump when driven by the output drive shaft for braking of the vehicle and to effect energy recovery, and the hydraulic drive motor power circuitry is operable to transfer pressurized hydraulic fluid from the hydraulic drive motor/pump to the energy storage device when the hydraulic drive motor/pump is reversely driven during braking,
3. A vehicle as set forth in claim 2, wherein the power take-off device is coupled to the drive shaft of the auxiliary hydraulic pump by a one way clutch.
4. A vehicle as set forth in claim 3, wherein the auxiliary hydraulic motor is coupled to the drive shaft of the auxiliary hydraulic pump by a one way clutch such that the auxiliary hydraulic pump will be driven by the power take off device or the auxiliary hydraulic motor that is being driven faster.
5. A vehicle as set forth in claim 1, wherein the transmission includes an output drive shaft connected to one or more wheels of the vehicle for transfer of power to the one or more wheels.
6. A vehicle as set forth in claim 1, wherein the energy storage device includes at least one hydropneumatic accumulator.
7. A vehicle as set forth in claim 6, the primary hydraulic pump power circuitry and hydraulic motor power circuitry includes hydraulic circuits respectively connecting the primary hydraulic pump and hydraulic motor to the at least one hydropneumatic accumulator.
8. A vehicle as set forth in claim 1, wherein the transmission assembly includes a clutch for selectively drivingly connecting the primary hydraulic pump to the power input shaft.
9. A vehicle as set forth in claim 8, wherein the transmission assembly includes a clutch for selectively drivingly connecting the output drive shaft to the power input shaft.
10. A vehicle as set forth in claim 1, wherein the prime mover is an internal combustion engine.
11. A power transfer system for a vehicle, comprising a power transfer apparatus for transferring power from a prime mover to the wheels of a vehicle for propelling the vehicle, the power transfer apparatus including a power input shaft connected to the prime mover, a primary hydraulic pump, a hydraulic motor/pump, a transmission assembly including a pump coupling for coupling the primary hydraulic pump to the power input shaft, a motor coupling for coupling the hydraulic motor to the output drive shaft, an energy storage device in which energy can be stored, primary hydraulic pump power circuitry for supplying pressurized hydraulic fluid from the primary hydraulic pump to the energy storage device, and hydraulic motor power circuitry for transferring pressurized hydraulic fluid from the energy storage device to the hydraulic motor; and an auxiliary hydraulic pump for supplying hydraulic fluid to an auxiliary hydraulic system of the vehicle other than one that effects vehicle propulsion; a power take-off device driven by the power input shaft and drivingly connected to a drive shaft of the auxiliary hydraulic pump; and an auxiliary hydraulic motor powered by pressurized hydraulic fluid from the energy storage device and drivingly connected to the drive shaft of the auxiliary hydraulic pump for driving the drive shaft of the auxiliary hydraulic pump when not driven by the power take-off device.
12. A power transfer system as set forth in claim 11, wherein the hydraulic drive motor is reversely operable as a hydraulic pump when driven by the output drive shaft for braking of the vehicle and to effect energy recovery, and the hydraulic drive motor power circuitry is operable to transfer pressurized hydraulic fluid from the hydraulic drive motor/pump to the energy storage device when the hydraulic drive motor/pump is reversely driven during braking,
13. A power transfer system as set forth in claim 12, wherein the power take-off device is coupled to the drive shaft of the auxiliary hydraulic pump by a one way clutch.
14. A power transfer system as set forth in claim 13, wherein the auxiliary hydraulic motor is coupled to the drive shaft of the auxiliary hydraulic pump by a one way clutch such that the auxiliary hydraulic pump will be driven by the power take off device or the auxiliary hydraulic motor that is being driven faster.
15. A power transfer system as set forth in claim 11, wherein the transmission includes an output drive shaft for driving one or more wheels of the vehicle for transfer of power to the one or more wheels.
16. A power transfer system as set forth in claim 11, wherein the energy storage device includes at least one hydropneumatic accumulator.
17. A power transfer system as set forth in claim 16, the primary hydraulic pump power circuitry and hydraulic motor power circuitry includes hydraulic circuits respectively connecting the primary hydraulic pump and hydraulic motor to the at least one hydropneumatic accumulator.
18. A power transfer system as set forth in claim 11, wherein the transmission assembly includes a clutch for selectively drivingly connecting the primary hydraulic pump to the power input shaft.
19. A power transfer system as set forth in claim 18, wherein the transmission assembly includes a clutch for selectively drivingly connecting the output drive shaft to the power input shaft.
Patent Application
20070227801
