GB2558300A

GB2558300A - Range extender electric vehicle with ancillary device

Info

Publication number: GB2558300A
Application number: GB1622349.7A
Authority: GB
Inventors: Jardine Ben
Original assignee: Arrival Ltd
Current assignee: Arrival UK Ltd
Priority date: 2016-12-29
Filing date: 2016-12-29
Publication date: 2018-07-11
Anticipated expiration: 2036-12-29
Also published as: GB2558300B; GB201622349D0

Abstract

A range-extender electric vehicle (REEV) 10, which may be a fire engine, includes a battery 22, an auxiliary power unit 28, which may be an internal combustion engine (ICE), and a generator 36 driven by the auxiliary power unit to charge the battery. An inverter 37 may be used between the generator and battery. An ancillary device 32, which may be a water pump, is mechanically driven by the auxiliary power unit and a coupling 34, such as a clutch, selectively engages and disengages the mechanical drive to the ancillary device. Gearbox 30 may be omitted from the system to drive the coupling and pump without gearing. If water inlet port 44 is connected to an external hydrant the difference in water pressure from the hydrant to a tank 38 may drive an impeller 46 to drive second generator 48 to provide additional charging of the battery.

Description

(54) Title of the Invention: Range extender electric vehicle with ancillary device

Abstract Title: A range extender electric vehicle with mechanically driven ancillary device (57) A range-extender electric vehicle (REEV) 10, which may be a fire engine, includes a battery 22, an auxiliary power unit 28, which may be an internal combustion engine (ICE), and a generator 36 driven by the auxiliary power unit to charge the battery. An inverter 37 may be used between the generator and battery. An ancillary device 32, which may be a water pump, is mechanically driven by the auxiliary power unit and a coupling 34, such as a clutch, selectively engages and disengages the mechanical drive to the ancillary device. Gearbox 30 may be omitted from the system to drive the coupling and pump without gearing. If water inlet port 44 is connected to an external hydrant the difference in water pressure from the hydrant to a tank 38 may drive an impeller 46 to drive second generator 48 to provide additional charging of the battery.

FIG. 1

12

2/2

110

- 1 Range Extender Electric Vehicle with Ancillary Device

Technical Field

The present invention relates to a range extender electric vehicle and, in particular, to a 5 range extender electric vehicle with an ancillary device which can be driven by the range extender motor.

Background

The drive for more fuel efficient and environmentally friendly transport solutions is seeing an increasing level of development in the field of electric vehicles. Such vehicles include not only passenger vehicles for personal transport, but also commercial and industrial vehicles such as buses and trucks. Such electric vehicles (EVs) include pure battery electric vehicles (BEVs) powered by batteries alone, and range extender electric vehicles (REEVs) which also include a range extender power unit, such as a small internal combustion engine (ICE), to generate electricity to supplement the battery power source.

Many commercial and industrial vehicles exist which include ancillary devices, for example pumps in a fire engine, winches in rescue vehicles, or rams in refuse trucks, tipper tricks, diggers, etc. However, such ancillary devices all require power and if driven from a battery, can quickly drain the battery of power, limiting the operational time period of the ancillary device.

Summary

In accordance with embodiments of the invention, there is provided a range-extender electric vehicle, comprising a battery, an auxiliary power unit, a generator configured to be driven by the auxiliary power unit to generate electricity to charge the battery, an ancillary device configured to be mechanically driven by the auxiliary power unit, and a coupling between the auxiliary power unit and the ancillary device configured to selectively engage and disengage the mechanical drive to the ancillary device.

The range-extender electric vehicle may further comprise at least one electric motor configured to be powered by the battery and to propel the range-extender electric vehicle. The at least one electric motor may be mechanically coupled to at least one wheel of the range-extender electric vehicle, and may be coupled via a drive gearbox to at least one wheel of the range-extender electric vehicle.

The coupling between the auxiliary power unit and the ancillary device may comprise a clutch.

The range-extender electric vehicle may further comprise a gearbox driven by the auxiliary power unit, and the ancillary device may be driven from a first output drive of the gearbox via the coupling. The generator may be driven from a second output drive of the gearbox.

A rotational input of the generator may be directly mechanically driven by a rotational output of the auxiliary power unit. The rotational input of the generator may be directly mechanically driven by a rotational output of the auxiliary power unit without change of rotational gear ratio.

The generator may include a rotational rotor shaft which is connected to and provides mechanical drive to the coupling. The generator may include a rotational rotor shaft which is connected to and provides mechanical drive to the coupling without change of rotational gear ratio.

A rotational output of the auxiliary power unit may be connected to the coupling via a rotor shaft of the generator without gearing to change the rotational drive ratio.

The generator may comprise a first generator, and the vehicle further comprises a second generator, and an impeller configured to drive the second generator to generate electricity to charge the battery.

The impeller may be fluidly connected to a water inlet port provided on the vehicle for connection to an external supply of pressurised water.

The range-extender electric vehicle may further comprise a water tank, and the impeller may be fluidly connected to the water tank to store water supplied to the vehicle via the water inlet port.

-3The ancillary device may comprise a water pump. The vehicle may comprise a fire engine.

The range-extender electric vehicle may further comprise a control apparatus configured to control operation of the vehicle.

The control apparatus may be configured to control actuation of the coupling to selectively engage and/or disengage the drive to the ancillary device.

The control apparatus may be configured to control operation of the ancillary device.

The control apparatus may be configured to control operation of a generator inverter that is connected between the generator which is driven by the auxiliary power unit, and the battery.

The control apparatus maybe configured to control operation of a second generator inverter that connected between the second generator and the battery.

The control apparatus may be configured to control operation of ancillary device and the generator inverter of the generator that is driven by the auxiliary power unit, such that the total power drawn by the ancillary device and provided to the generator is maintained at or within a predetermined margin of a predetermined value.

The predetermined power value may comprise a value equal to a power output of the auxiliary power unit when running at or within predetermined margin of its optimum efficiency.

The vehicle may be configured to be able to simultaneously mechanically drive the ancillary device and generate electricity to charge the battery by the generator.

The auxiliary power unit may comprise an internal combustion engine.

The present invention also provides a method of operating a range-extender electric vehicle, the vehicle comprising a battery, an auxiliary power unit, a generator configured to be driven by the auxiliary power unit to generate electricity to charge the battery, an ancillary device configured to be mechanically driven by the auxiliary power

-4unit, and a coupling between the auxiliary power unit and the ancillary device, the method comprising mechanically coupling the auxiliary power unit to the ancillary device via the coupling, and mechanically driving the ancillary device by the auxiliary power unit.

The method may comprise operating a clutch as the coupling between the auxiliary power unit and the ancillary device.

The method may comprise driving a gearbox by the auxiliary power unit, and driving the ancillary device from a first output drive of the gearbox via the coupling.

The method may comprise driving the generator from a second output drive of the gearbox.

The method may comprise directly mechanically driving a rotational input of the generator by a rotational output of the auxiliary power unit, and may comprise mechanically driving a rotational input of the generator by a rotational output of the auxiliary power unit without change of rotational gear ratio.

The method may comprise providing mechanical drive to the coupling by a rotational rotor shaft of the generator which is connected to the coupling and may comprise providing mechanical drive to the coupling by a rotational rotor shaft of the generator which is connected to the coupling without change of rotational gear ratio.

The method may comprise providing rotational drive from a rotational output of the auxiliary power unit which is connected to the coupling via a rotor shaft of the generator, without gearing to change the rotational drive ratio.

The generator may comprise a first generator, and the vehicle may further comprise a second generator, and an impeller configured to drive the second generator, and the method may comprise the impeller driving the second generator to generate electricity to charge the battery.

The method may comprise driving the impeller by passing pressurised water over the impeller from a water inlet port provided on the vehicle and fluidly connected to the

-5impeller.

The method may comprise controlling operation of the ancillary device and the generator inverter of the generator that is driven by the auxiliary power unit, such that the total power drawn by the ancillary device and provided to the generator is maintained at or within a predetermined margin of a predetermined value.

The method may comprise simultaneously mechanically driving the ancillary device and generating electricity to charge the battery by the generator.

Brief Description of the Drawings

Embodiments of the present invention will now be described, byway of example only, with reference to the accompanying drawings, in which:

Fig. l shows a schematic view of a vehicle including an ancillary device of a first embodiment of the invention; and

Fig. 2 shows a schematic view of a vehicle including an ancillary device of a second embodiment of the invention.

Detailed Description

Fig. l shows a schematic view of a range extender electric vehicle of a first embodiment of the invention. In the exemplary embodiment shown in Fig. l, the vehicle comprises a range extender electric fire engine or fire truck io, and the ancillary device comprises a water pump on the fire truck, although, as explained later, the invention is not intended to be limited to such a vehicle.

The vehicle io comprises a chassis or body 12 and four wheels 14. A motor 16 drives two of the wheels via a drive gearbox 18 and two drive shafts 20. The other two wheels may similarly be driven by another similar motor and gearbox arrangement (not shown), or the vehicle 10 may only comprise two drive wheels. A battery 22 powers the motor 16 via a Power Distribution Unit (PDU) 24 which comprises a traction inverter.

-6The PDU 24 is controlled by a control apparatus 26 which comprises a Drive Control Unit (DCU).

An auxiliary power unit or “range extender” (hereafter “RE unit”) 28 is connected to an auxiliary gearbox 30. The RE unit 28 may comprise an internal combustion engine, although other power units are intended within the scope of the invention. An output shaft of the RE unit 28 is mechanically connected to the auxiliary gearbox 30 to provide rotational drive to the gearbox. A pump 32 is mechanically driven by the RE unit 28 via the auxiliary gearbox 30, from a first output from the auxiliary gearbox 30. The pump 32 is connected to the auxiliary gearbox 30 via a clutch unit 34. The clutch unit 34 enables drive from the RE unit 28/ auxiliary gearbox 30 to selectively be engaged or disengaged from the pump 32. The clutch unit 34 may comprise, for example, a clutch comprising engagable clutch plates (not shown), and an actuator (not shown) operable to engage and disengage the clutch.

The RE unit 28 also drives a first or “RE” generator 36 via a second output from the auxiliary gearbox 30. The RE generator 36 is electrically connected to the battery 22 via a first or “RE” generator inverter 37 and is configured to charge the battery 22 when driven by the RE unit 28.

The vehicle 10 further comprises a water tank 38 with a tank outlet 40 fluidly connected to the pump 32. A tank inlet 42 is fluidly connected to a vehicle water inlet port (hereafter “inlet port”) 44. An impeller 46 is provided in the fluid duct between the inlet port 44 and the tank inlet 42. The impeller 46 is mechanically connected to a second generator 48 and is configured such that rotational drive from the impeller 46 drives the second generator 48. The second generator 48 is electrically connected to the battery 22 via a second generator inverter 49 and is configured to charge the battery 22 when driven by the impeller 46. An outlet of the pump 32 is fluidly connected to a vehicle water outlet port (hereafter “outlet port”) 50.

The DCU or control apparatus 26 is connected to, and configured to control operation of, the RE unit 28, pump 32, clutch unit 34, the RE generator inverter 37 and second generator inverter 49. As described herein, the control apparatus 26 may comprise one or more controllers, provided together or distributed around vehicle, and may, for example, comprise a pump controller, a clutch unit controller, an RE unit controller, an RE generator inverter controller and a second generator inverter controller.

-ΊOperation of the fire truck io of the first exemplary embodiment of the invention will now be described. In normal driving circumstances, or when driving to a location where the vehicle io service is required, the vehicle may operate in full electric vehicle mode, in which the motor 16 is powered by the battery 22, and the RE unit 28 is not operating. This may particularly be advantageous if the travelled route includes low emission zone areas. If during driving the battery 22 charge level becomes too low, or the route is longer than the battery alone may be able to power the vehicle, the RE unit 28 may be controlled to operate as necessary to maintain the charge in the battery 22 by electricity generation via the auxiliary gearbox 30, RE generator 36 and RE generator inverter 37.

When the vehicle 10 arrives at the location of the fire, the control apparatus 26 can control the RE unit 28 to operate and the clutch unit 34 to engage to drive the pump 32 to pump water from the water tank 38 out of the outlet port 50 to tackle the fire.

During this operation, the battery charge 22 is not being depleted as the vehicle 10 is not moving and the battery power is not being used to operate the pump 32. It will be appreciated however, that a small amount of power maybe required from the battery for vehicle electrical systems such as lights, communication systems, heating, etc., although the power requirements of such systems are significantly less than that required to propel the vehicle 10 by means of the motor 16.

The RE unit will be a power generating unit which will have an optimum operating speed for maximum efficiency. For example, the RE unit may comprise an internal combustion engine with an operating condition of maximum efficiency generating lfiokW. This power output may be more than is required to drive the pump 32. An option would therefore be to run the RE unit at a lower speed or lower power output to match the pump 32 power demand. However, this would be an inefficient condition in which to operate the RE unit 28. Therefore, as an alternative, the control apparatus 26 can control the RE unit 28 to continually run at a constant speed of maximum efficiency (or within a predetermined margin of the maximum efficiency for example within 10%), and control the RE generator 36 and RE generator inverter 37 such that the RE generator 36 runs simultaneously with the pump 32 so that the excess power produced by the RE unit 28 is converted by the RE generator 36 and RE generator inverter 37 into electrical energy to charge the battery 22. The control apparatus 26 may continue to balance the power generated by the RE generator 36 and converted by

-8the RE generator inverter 37 with the power demanded by the pump 32, to maintain the sum power drawn by the pump 32 and RE generator 36 to be equal to the power output of the RE unit 28 running in its most efficient operating condition, for example, a total output of isokW in the example given above. The control apparatus 26 may actively manage the power generated by the RE generator 36 by control of the RE generator inverter 37 to vary depending on the varying power demands of the pump 32. For example, if fire fighters operating the fire truck 10 initially want a maximum water flow rate by the pump 32, the control apparatus 26 will operate the RE generator 36 and RE generator inverter 37 to generate power equal to the difference between the RE unit 28 power output running in its most efficient operating condition and the power demanded by the pump 32. Then, once a fire is getting under control, the water flow rate demanded may drop, in which case the pump 32 will operate at a lower rate, demanding less power, and the control apparatus 26 will consequently control the RE generator 36 and RE generator inverter 37 to generate more electrical power to charge the battery 22 such that the sum of the power demanded by the pump 32 and the power generated by the RE generator 36/RE generator inverter 37 remains equal to the power output of the RE unit 28 running in its most efficient operating condition.

A further advantage of a fire truck 10 of the first exemplary embodiment of the invention lies in the provision of the second generator 48 driven by the impeller 46. In a conventional fire engine, a water tank is provided which can be filled from a fire hydrant. The water supply in the hydrant is under high pressure, and this water pressure is lost as the water is fed into the fire engine’s water tank, as the fire engine water tank is not pressurised. In the fire truck 10 of the first embodiment of the invention however, when the water tank 38 is to be filled from a fire hydrant, a hose is connected from the fire hydrant to the inlet port 44, and water under high pressure is fed into the inlet port 44, past the impeller 46 and into the water tank 38 through the tank inlet 42. As the high pressure water flows over the impeller 46, the impeller 46 is forced to rotate and drives the second generator 48 which in turn generates electricity which, via the second generator inverter 49, is used to charge the battery 22. The control apparatus 26 controls operation of the second generator inverter 49 in charging the battery 22. The fire truck 10 can therefore harvest energy in the high pressure water flowing into the vehicle and convert a proportion of the energy into electrical energy and store this electrical energy. This can be performed whenever the water tank 38 is being filled with water, independently of whether the pump 32 is being operated or the RE unit 28 is running.

-9Fig. 2 shows a schematic view of a range extender electric vehicle no of a second embodiment of the invention, which is similar to the vehicle io of the first embodiment, and in which like features retain the same reference numerals and description thereof will not be repeated again.

A difference with the vehicle no of the second embodiment is that the RE unit 28 directly drives the RE generator 36, and the auxiliary gearbox 30 is omitted. A drive shaft 31 extends directly from the RE unit 28, through the RE generator 36, and comprises the rotor shaft of the RE generator 36. The drive shaft 31 is connected directly to the clutch unit 34 such that mechanical drive is communicated directly from the RE unit 28 to the clutch unit 34 via the RE generator 36. The drive shaft 31 may comprise separate sections connected together, for ease of manufacture and assembly, so may or may not be a single unitary component extending from the RE unit 28, through the RE generator 36 and to the clutch unit 34. In embodiments, the rotational drive is coupled from the RE unit 28, to the RE generator 36, and to the clutch unit 34 without gearing reduction or increase. As with the first embodiment shown in Fig. 1, the RE generator 36 is electrically connected to the battery 22 via a first or “RE” generator inverter 37 and is configured to charge the battery 22 when the RE generator 36 is driven by the RE unit 28.

A pump 132 is provided which includes a gearbox (not shown) with a gearing ratio to reduce or increase, as necessary, the rotational drive speed from the drive shaft 31 driven by the RE unit 28, to a rotational speed appropriate for operation of the pump 132. The gearbox (not shown) maybe connected directly to the pump 132, or maybe formed integrally with the pump 132 as a combined pump/gearbox unit.

An advantage of the arrangement of the second embodiment of the invention is that there is no need for the auxiliary gearbox 30, so reducing weight, reducing mechanical losses, and reducing cost, and resulting in a simpler construction. The gearing being provided by a gear box (not shown) within the pump 132 or a gear box (not shown) coupled to the pump 132, may allow for a smaller and simpler, thereby lighter and less costly gearing system. It is intended that the pump 132 may alternatively be replaced with a pump 32 of the first embodiment, without a gearbox, such that the pump 32 is driven directly by, and at the same rotational speed as, the output drive of the RE unit 28. Yet further, it is intended within the scope of the invention, that the pump 132 may

- 10 be replaced with a pump 32 of the first embodiment, and a gearbox (not shown) may be provided as a separate entity disposed between the clutch unit 34 and the pump 32.

Operation of the vehicle 110 of the second exemplary embodiment is the same as described previously with respect to the vehicle 10 of the first exemplary embodiment.

It will be appreciated from the above description that vehicles of the present invention provide a number of advantages over known configurations of such vehicles having ancillary devices which draw power. Previously, vehicles with ancillary devices requiring power need an internal combustion engine running to power them, that being either the main vehicle engine or separate power generator unit. With battery powered electric vehicles, running ancillary devices from the main vehicle battery could rapidly drain the battery and thereby limit the usable time vehicle could operate, for example how long a fire engine could pump water to a fire. This would make pure electric vehicle fire engines, for example, unfeasible, due to current battery architecture. However, adding a separate power unit solely to power the ancillary devices to avoid draining the vehicle main battery would add weight and cost, particularly disadvantageous factors in the context of electric vehicles. The solution provided by the present invention utilises RE unit already present in REEVs to enable ancillary devices to operate for long periods of time, without draining the battery, or requiring an additional separate generator. This thereby renders range-extender electric vehicles feasible for use as service vehicles such as fire engines. Additionally, embodiments of the invention in the context of fire trucks may harvest conventionally wasted energy in pressurised water supply. These numerous benefits all help towards providing a more efficient, greener, and more environmentally friendly vehicle.

Although the exemplary embodiment of the invention is described above as a fire truck, the invention is not intended to be limited to fire trucks, and may include other forms of range extender electric vehicles which comprise ancillary devices which draw power and may require operation independently of the motive power of the vehicle. For example, the invention may comprise a range extender trash collection vehicle, which may include a trash compactor which may be mechanically driven via an engagable mechanical coupling with the RE unit and optionally via a gearbox. The invention may alternatively comprise a range-extender rescue vehicle which may include a rescue winch which may be mechanically driven via an engagable mechanical coupling with the RE unit, again optionally via a gearbox. Yet further, the invention may comprise

- 11 any number of range extender construction or excavation vehicles, such as a tipper truck or digger. In such vehicles, the tipping load carrier or other moveable tool may be which may be mechanically driven via an engagable mechanical coupling with the RE unit, optionally via a gearbox. Such vehicles may include ram-powered tools, such as an excavator arm or tipping load carrier, and the hydraulic or pneumatic pressure for ram operation may be provided by a fluid pump which may be mechanically driven via a engagable mechanical coupling with the RE unit. In any exemplary vehicle of the invention, the vehicle may be provided with cutting or other equipment, particularly in the context of a fire truck. Such cutting equipment may be mechanically powered via an engagable mechanical coupling with the RE unit, optionally via a gearbox.

Herein, embodiments of the invention are described as having an ancillary device which is driven by an auxiliary power source such as an RE unit. This should be interpreted as meaning such ancillary devices may be directly driven by such auxiliary power unit, or driven via one or more intermediate power-transmission mechanisms, such as a gearbox, reduction gear, transmission, or other suitable mechanism.

The embodiments of the invention shown in the drawings and described above are exemplary⁷ embodiments only and are not intended to limit the scope of the invention, which is defined by the claims hereafter. It is intended that any combination of nonmutually exclusive features described herein are within the scope of the present invention.

Claims

1. A range-extender electric vehicle, comprising:

a battery;

an auxiliary power unit;

a generator configured to be driven by the auxiliary power unit to generate electricity to charge the battery;

an ancillary device configured to be mechanically driven by the auxiliary power unit; and a coupling between the auxiliary power unit and the ancillary device configured to selectively engage and disengage the mechanical drive to the ancillary device.

2. A range-extender electric vehicle according to claim l, wherein the coupling between the auxiliary power unit and the ancillary device comprises a clutch.

3. A range-extender electric vehicle according to claim l or claim 2 further comprising a gearbox driven by the auxiliary power unit, and wherein the ancillary device is driven from a first output drive of the gearbox via the coupling.

4. A range-extender electric vehicle according to claim 3 wherein the generator is driven from a second output drive of the gearbox.

5. A range-extender electric vehicle according to claim 1 or claim 2 wherein a rotational input of the generator is directly mechanically driven by a rotational output of the auxiliary power unit.

6. A range-extender electric vehicle according to claim 1 or claim 2 wherein the generator includes a rotational rotor shaft which is connected to and provides mechanical drive to the coupling.

7. A range-extender electric vehicle according to any of claims 1, 2,5 or 6, wherein a rotational output of the auxiliary power unit is connected to the coupling via a rotor shaft of the generator without gearing to change the rotational drive ratio.

-138. A range-extender electric vehicle according to any of claims l to 7 wherein the generator comprises a first generator, and the vehicle further comprises a second generator, and an impeller configured to drive the second generator to generate electricity to charge the battery.

9. A range-extender electric vehicle according to claim 8 wherein the impeller is fluidly connected to a water inlet port provided on the vehicle for connection to an external supply of pressurised water.

10. A range-extender electric vehicle according to claim 9 further comprising a water tank, and wherein the impeller is fluidly connected to the water tank to store water supplied to the vehicle via the water inlet port.

11. A range-extender electric vehicle according to any of claims 1 to 10 wherein the ancillary device comprises a water pump.

12. A range-extender electric vehicle according to claim 11 wherein the vehicle comprises a fire engine.

13. A range-extender electric vehicle according to any preceding claim, further comprising a control apparatus configured to control operation of the vehicle.

14. A range-extender electric vehicle according to claim 13 wherein the control apparatus is configured to control actuation of the coupling to selectively engage and/or disengage the drive to the ancillary device.

15. A range-extender electric vehicle according to claim 13 or claim 14 wherein the control apparatus is configured to control operation of the ancillary device.

16. A range-extender electric vehicle according to any of claims 13 to 15, wherein the control apparatus is configured to control operation of a generator inverter that is connected between the generator which is driven by the auxiliary power unit, and the battery.

17. A range-extender electric vehicle according to any of claims 13 to 16, wherein the control apparatus is configured to control operation of a second generator

-14inverter that connected between the second generator and the battery.

18. A range-extender electric vehicle according to any of claims 13 to 17, wherein the control apparatus is configured to control operation of ancillary device and the generator inverter of the generator that is driven by the auxiliary power unit, such that the total power drawn by the ancillary device and provided to the generator is maintained at or within a predetermined margin of a predetermined value.

19. A range-extender electric vehicle according to claim 18 wherein the predetermined power value comprises a value equal to a power output of the auxiliary power unit when running at or within predetermined margin of its optimum efficiency.

20. A range-extender electric vehicle according to any preceding claim wherein the vehicle is configured to be able to simultaneously mechanically drive the ancillary device and generate electricity to charge the battery by the generator.

21. A range-extender electric vehicle according to any preceding claim wherein the auxiliary power unit comprises an internal combustion engine.

22. A method of operating a range-extender electric vehicle, the vehicle comprising a battery, an auxiliary power unit, a generator configured to be driven by the auxiliary power unit to generate electricity to charge the battery, an ancillary device configured to be mechanically driven by the auxiliary power unit, and a coupling between the auxiliary power unit and the ancillary device, the method comprising mechanically coupling the auxiliary power unit to the ancillary device via the coupling, and mechanically driving the ancillary device by the auxiliary power unit.

23. A method according to claim 22 comprising operating a clutch as the coupling between the auxiliary power unit and the ancillary device.

24. A method according to claim 22 or claim 23 comprising driving a gearbox by the auxiliary power unit, and comprising driving the ancillary device from a first

-15output drive of the gearbox via the coupling.

25. A method according to claim 24, comprising driving the generator from a second output drive of the gearbox.

26. A method according to claim 22 or claim 23 comprising directly mechanically driving a rotational input of the generator by a rotational output of the auxiliary power unit.

27. A method according to claim 22 or claim 23 comprising providing mechanical drive to the coupling by a rotational rotor shaft of the generator which is connected to the coupling.

28. A method according to any of claims 22, 23, 26 or 27, comprising providing rotational drive from a rotational output of the auxiliary power unit which is connected to the coupling via a rotor shaft of the generator, without gearing to change the rotational drive ratio.

29. A method according to any of claims 22 to 28, wherein the generator comprises a first generator, and the vehicle further comprises a second generator, and an impeller configured to drive the second generator, the method comprising the impeller driving the second generator to generate electricity to charge the battery.

30. A method according to claim 29, comprising driving the impeller by passing pressurised water over the impeller from a water inlet port provided on the vehicle and fluidly connected to the impeller.

31. A method according to any of claims 22 to 30 comprising controlling operation of the ancillary device and the generator inverter of the generator that is driven by the auxiliary power unit, such that the total power drawn by the ancillary device and provided to the generator is maintained at or within a predetermined margin of a predetermined value.

32. A method according to claim 31 wherein the predetermined power value comprises a value equal to a power output of the auxiliary power unit when

-ι6running at or within predetermined margin of its optimum efficiency.

33. A method according to any of claims 22 to 32 comprising simultaneously mechanically driving the ancillary device and generating electricity to charge the

5 battery by the generator.

Intellectual

Property

Office

Application No: GB1622349.7 Examiner: Mr Tony Walbeoff