GB2550555A

GB2550555A - System for a drive line of a vehicle

Info

Publication number: GB2550555A
Application number: GB1608577.1A
Authority: GB
Inventors: Desmond Alexander
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2016-05-16
Filing date: 2016-05-16
Publication date: 2017-11-29
Anticipated expiration: 2036-05-16
Also published as: GB2550555B; GB201608577D0

Abstract

A system 200 for a drive line of a vehicle (Fig.1, 100), comprises: mechanical drive line means 201 enabling a first vehicle wheel 101, on a first side 103 of the vehicle 100, to be mechanically driven by a combustion engine 105; and electrical drive line means 203 enabling a second different vehicle wheel 107, on a second different side 109 of the vehicle 100, to be electrically driven using electrical energy generated from the mechanical drive line means 201. The first and second wheels may be located at left and right sides of the vehicle, at the front. The electrical driveline means may be operated simultaneously to the mechanical driveline means. The mechanical drive line may drive all of the wheels apart from the second wheel. The electrical driveline means may comprise two electric motors, coupled to each other, and at least one motor coupled to the mechanical driveline. A method of electronically providing a differential and a method of boosting vehicle torque is also claimed.

Description

SYSTEM FOR A DRIVE LINE OF A VEHICLE

TECHNICAL FIELD

The present disclosure relates to a system for a drive line of a vehicle. In particular, but not exclusively, it relates to a system for enabling a drive line to fit within a vehicle, unobstructed by other vehicle components.

Aspects of the invention relate to a system, a vehicle, a method and a controller. BACKGROUND A drive line of a vehicle supplies torque from the powertrain, typically an internal combustion engine to the vehicle wheels. Rotating interconnected mechanical components in the drive line cause rotational energy of the internal combustion engine to drive the vehicle wheels.

Part of the drive line may need to pass under the powertrain or around an obstruction prohibiting a direct path to reach a vehicle wheel. Typically a transverse intermediate drive shaft is a rotatable mechanical component which enables the drive line to pass under the internal combustion engine. The transverse intermediate drive shaft is mechanically coupled to an axle at each end. Therefore the transverse intermediate drive shaft completes an axle arrangement enabling both left and right vehicle wheels to be driven.

The powertrain or any obstruction may be large or may be mounted within the vehicle in an obstructive way. In such circumstances it may be difficult to package the transverse intermediate drive shaft within the vehicle.

The powertrain may need to be downsized or re-positioned to allow the transverse intermediate drive shaft to pass underneath. Re-positioning the powertrain to allow the transverse intermediate drive shaft to pass underneath may raise the centre of gravity of the vehicle significantly, impairing the handling characteristics of the vehicle.

It is an aim of the present invention to address such disadvantages.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a system, a vehicle, a method and a controller as claimed in the appended claims.

According to a first aspect of the invention there is provided a system for a drive line of a vehicle, the system comprising: mechanical drive line means enabling a first vehicle wheel, on a first side of the vehicle, to be mechanically driven by a combustion engine; and electrical drive line means enabling a second different vehicle wheel, on a second different side of the vehicle, to be electrically driven using electrical energy generated from the mechanical drive line means. An advantage is that there is no need for a transverse intermediate drive shaft, enabling greater flexibility over the sizing and positioning of the internal combustion engine.

Mechanical driving comprises driving by an internal combustion engine or an external combustion engine. In a hybrid electric vehicle, an electric motor may additionally be provided for driving the mechanical drive line means. A drive line relates to any means for supplying torque from a combustion engine to the vehicle wheels. The electrical drive line means may be an electrical drive line. The mechanical drive line means may be a mechanical drive line which in some examples may comprise the combustion engine.

The system may be configured to enable the second vehicle wheel to be electrically driven using electrical energy generated from the mechanical drive line means at the same time as the first vehicle wheel is mechanically driven by the combustion engine. An advantage is that the system enables torque to be sent to both sides, helping the vehicle to drive in a straight line when required.

The electrical drive line means may comprise at least an electrical cable electrically coupling a first electric machine to a second electric machine, wherein the first electric machine is electrically coupled to the mechanical drive line means. The first electric machine, second electric machine, and electrical cable together provide the function of a mechanical transverse intermediate drive shaft, advantageously not requiring such a drive shaft.

The first electric machine may be positioned, within the system, to be located on the first side of the vehicle, and the second electric machine may be positioned, within the system, to be located on the second side of the vehicle. A second vehicle wheel axle for driving the second vehicle wheel, and the second electric machine, may be on the second side of the vehicle. A first vehicle wheel axle for driving the first vehicle wheel, and the first electric machine, may be on the first side of the vehicle.

An axis of rotation of the second vehicle wheel and/or an axis of rotation of a second vehicle wheel axle for driving the second vehicle wheel may pass through the second electric machine. An axis of rotation of a first vehicle wheel axle for driving the first vehicle wheel and/or an axis of rotation of the first vehicle wheel may pass through the first electric machine. The electrical drive line means may therefore be aligned to the vehicle wheels.

The electrical drive line means may divert around a region for receiving at least part of the combustion engine. Electrical drive line means are easier to fit within the vehicle than their mechanical equivalents. No rigid rotating shafts and complex linkages are required, as flexible electrical cables may be used. This enables the combustion engine to be large and/or at a low position within the vehicle.

According to some, but not necessarily all examples, the region is for receiving any vehicle component or large structure and is not limited to a combustion engine. For example the obstruction could be formed by part of a vehicle transmission.

The system may comprise one or more switched reluctance machines. An advantage of switched reluctance machines includes enabling the exact rotor position to be known, as switched reluctance machines do not slip like induction motors. Another advantage is there is no need for a high-maintenance mechanical commutator, as a simple electronic position sensor and solid state electronics can instead be used. Switched reluctance machines also allow the dynamic control of pulse timing and shaping.

The system may comprise a wheel hub electric machine. An advantage is that no second vehicle wheel axle would be required for the second vehicle wheel, reducing the number of moving and interconnected parts and reducing weight.

The system may comprise a second vehicle wheel axle for driving the second vehicle wheel, wherein the second vehicle wheel axle may be mechanically decoupled from the mechanical drive line means. The second electric machine may drive the second vehicle wheel axle. An advantage is that the second electric machine can be separated from the wheel hub of the second vehicle wheel, reducing exposure of the second electric machine to an external environment. A portion of the mechanical drive line means and/or a rotatable rigid component or shaft arranged to rotate the second vehicle wheel may comprise magnetic poles projecting radially outwardly from its axis of rotation in a rotor formation. A portion of the mechanical drive line means may easily be converted to a rotor for a switched reluctance machine. There is no need for the rotor to have coils.

The mechanical drive line means and/or the electrical drive line means may comprise differential means configured to enable torque vectoring for the first vehicle wheel and second vehicle wheel. An advantage is improved vehicle handling.

The mechanical drive line means may comprise a mechanical differential for positioning on the first side of the vehicle. The mechanical differential may have an input for receiving energy from the combustion engine, a first output enabling mechanical driving of the first vehicle wheel, and a second different output enabling electrical energy to be generated from the mechanical drive line means for electrical driving of the second vehicle wheel.

The first electric machine may be for positioning on the first side of the vehicle and may be positioned proximal to the second different output of the mechanical differential. The second electric machine may be for positioning on the second side of the vehicle and for electrical connection in series to the first electric machine, enabling electrical energy to pass between the first electric machine and the second electric machine.

The electrical drive line means may comprise an electrical energy storage device. The electrical energy storage device may comprise a capacitor or a battery. An advantage is that the electrical energy storage device may be configured to provide the functionality of the differential means, therefore avoiding the need for a mechanical differential, potentially saving weight and reducing drive line losses. Another advantage is the electrical energy storage device can be configured to store electrical energy and use the energy to accelerate the vehicle.

The electrical drive line means may comprise selectable bypass means to enable electrical bypassing of the electrical energy storage device. An advantage is enabling torque to reach the vehicle wheels without unwanted modification of torque characteristics by the electrical energy storage device.

The first vehicle wheel and the second vehicle wheel may be front wheels of the vehicle. The combustion engine may be positioned within an engine bay at the front of the vehicle. The combustion engine may comprise any number of internal combustion cylinders, in some examples more than four internal combustion cylinders. The internal combustion cylinders may be arranged in one or more parallel rows. The row or rows may extend parallel (longitudinally) or transverse to a forward direction of motion of the vehicle. The combustion engine may be longitudinally mounted within the front of the vehicle and may comprise more than four in-line cylinders. An advantage of the system is enabling a small and confined engine bay to accommodate a large combustion engine.

The vehicle may comprise any number of wheels, in some examples four wheels. The mechanical drive line means may be configured to enable mechanical driving of all of the vehicle wheels of the vehicle apart from the second vehicle wheel. If the vehicle comprises four wheels, this may provide an unusual four-wheel drive layout in which three wheels are mechanically driven and one wheel is electrically driven. An advantage of the system is that it is possible to utilize various four-wheel drive or all-wheel drive configurations for a vehicle despite difficult access to at least one vehicle wheel, for example due to obstruction by a combustion engine.

According to another aspect of the invention there is provided a vehicle comprising the system as described herein.

According to a further aspect of the present invention there is provided a method of electronically providing a differential for a vehicle, wherein a first vehicle wheel on a first side of the vehicle is arranged to be mechanically driven by mechanical drive line means mechanically connected to a combustion engine, wherein a second different vehicle wheel on a second different side of the vehicle is arranged to be simultaneously electrically driven by electrical drive line means using electrical energy generated from the mechanical drive line means, the method comprising: determining that the second vehicle wheel is slipping; and in response to the determination, enabling an electrical energy storage device comprised in the electrical drive line means to store electrical energy within the electrical energy storage device. An advantage is that the electrical energy storage device may be configured to provide the functionality of the differential means, therefore avoiding the need for mechanical differential means, potentially saving weight and reducing drive line losses. The energy storage device may comprise a capacitor or a battery.

According to a further aspect of the present invention there is provided a method of boosting torque of a vehicle, wherein while a first vehicle wheel on a first side of the vehicle is mechanically driven by mechanical drive line means mechanically connected to a combustion engine, the method comprises: discharging an electrical energy storage device comprised in electrical drive line means to electrically drive a second different vehicle wheel on a second different side of the vehicle. An advantage is that vehicle acceleration may be increased temporarily. This is because two propulsion methods are adopted simultaneously for driving, namely the combustion engine and the electrical energy storage device.

According to a further aspect of the present invention there is provided a controller comprising means configured to perform the operations of any one or combination of the methods described herein.

According to some, but not necessarily all examples, there is provided a system comprising: means for mechanically driving a first lateral vehicle wheel; and means for electrically driving a second lateral vehicle wheel at least at the same time.

According to a further aspect of the present invention there is provided a system for a drive train of a vehicle, the system comprising: a first torque transfer component, having a first axis of rotation, configured to transfer torque supplied by a combustion engine to a first vehicle wheel; a second torque transfer component, having a second axis of rotation, configured to transfer torque to a second vehicle wheel; a generator configured to convert torque supplied by the combustion engine into electrical energy; a motor configured to convert electrical energy supplied by the generator into torque of the second torque transfer component, and configured to operate at the same time as the generator; and an electrical transmission arrangement configured to provide the electrical energy from the generator to the motor, and configured to divert around a structure positioned between the first torque transfer component and the second torque transfer component. The first torque transfer component may be a first vehicle wheel axle. The second torque transfer component may be a second vehicle wheel axle or hub. The electrical transmission arrangement may be an electrical cable.

The system may be a system for enabling a portion of a drive line to fit within a vehicle.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG 1 illustrates an example of a vehicle. FIG 2 illustrates an example of a system. FIG 3 illustrates another example of a system. FIG 4 illustrates another example of a system. FIG 5 illustrates an example of a vehicle and an internal combustion engine. FIG 6 illustrates an example of a switched reluctance machine.

DETAILED DESCRIPTION

Examples in the present disclosure relate to a system for enabling a portion of a drive line to fit within a vehicle, unobstructed by other vehicle components.

It will be helpful when initially describing an example of the system 200 for a drive line of a vehicle 100 to refer to features of FIG 1. FIG 1 illustrates a vehicle 100 in front elevation. The vehicle 100 comprises an engine bay 111, a first vehicle wheel 101 on a first side 103 of the vehicle 100 and a second different vehicle wheel 107 on a second different side 109 of the vehicle 100. In some examples the engine bay 111 is at the front end of the vehicle 100, as illustrated in FIG 1. In other examples the engine bay 111 is at the rear end of the vehicle 100.

The terms ‘first side 103’ and ‘second different side 109’ are understood to refer to sides relative to a longitudinal axis 102. The longitudinal axis 102 is equally separated from the first vehicle wheel 101 and from the second vehicle wheel 107, and extends in a direction corresponding to a forwards and reverse driving direction of the vehicle 100. The first side 103 is one side of the longitudinal axis 102. The second different side 109 is the other side of the longitudinal axis 102. The first side 103 and second side 109 are transverse sides of the vehicle. References to ‘longitudinal’ refer to a position along the longitudinal axis 102. References to ‘transverse’ refer to a horizontal direction orthogonal to the longitudinal axis 102. FIGS 2 to 4 are simplified schematic diagrams illustrating examples of a system 200 for a drive line of a vehicle 100, the system comprising: mechanical drive line means 201 enabling a first vehicle wheel 101, on a first side 103 of the vehicle 100, to be mechanically driven by a combustion engine 105; and electrical drive line means 203 enabling a second different vehicle wheel 107, on a second different side 109 of the vehicle 100, to be electrically driven using electrical energy generated from the mechanical drive line means 201.

The term mechanical drive line means 201 would be understood to include any rotatable rigid mechanical components such as drive shafts, axles, joints and rotating parts of differentials, interconnected to form a continuous mechanical chain for transmitting mechanical energy, from an output of a powertrain to one or more vehicle wheels. Mechanical energy comprises mechanical kinetic energy, mechanical potential energy, or the sum thereof. The mechanical drive line means transmits mechanical energy by means of rotation of the mechanical components.

The mechanical drive line means 201 enables the first vehicle wheel 101 on the first side 103 to be mechanically driven in at least a forward direction of travel by the combustion engine 105. In some, but not necessarily all examples, the mechanical drive line means 201 is configured as part of a four-wheel drive system or all-wheel drive system to enable mechanical driving of all of the vehicle wheels of the vehicle apart from the second vehicle wheel 107.

The electrical drive line means 203 enables the second vehicle wheel 107 on the second side 109 to be electrically driven in at least the forward direction of travel. The term electrical drive line means 203 would be understood to include any electrical components such as components of electric machines, electrical energy storage devices, electrical cables and other electric circuit components which are capable of transmitting electrical energy, not mechanical energy, to provide the functionality of one or more mechanical components of the mechanical drive line means 201. Electrical energy includes electric potential energy.

The system 200 may be used in various types of vehicles 100. Before describing the system 200 in further detail it would be useful to provide an example of a vehicle 100 which may be used in conjunction with the system 200.

In an example vehicle 100, the first vehicle wheel 101 and the second vehicle wheel 107 are front steerable wheels of the vehicle 100. The vehicle 100 is a front-engined vehicle. The engine bay 111 is at the front of the vehicle 100 between the first vehicle wheel 101 and second vehicle wheel 107.

In some, but not necessarily all examples, the combustion engine is an internal combustion engine 105. The internal combustion engine 105 is longitudinally mounted within the engine bay 111 and may comprise more than four in-line combustion cylinders (not shown). The internal combustion engine 105 may comprise six or more in-line combustion cylinders. Longitudinal mounting refers to the in-line combustion cylinders being arranged substantially parallel to the longitudinal axis 102.

In some, but not necessarily all examples, the example vehicle 100 is a passenger car. The example vehicle 100 may have a coupe body. The vehicle 100 may be a sports car having a maximum roof height of, for example, 1.2 to 1.5 metres above the ground. The vehicle 100 may have restricted space in the engine bay 111. For example the engine bay 111 may have a restricted height.

In some, but not necessarily all examples, at least part of the system 200 is arranged to be fitted within the engine bay 111 of the vehicle 100 and adjacent the internal combustion engine 105.

Several examples of the system 200 for the example vehicle 100 or any other suitable vehicle 100 will now be described, with reference to FIGS 2 to 6. FIG 2 is an example of the system 200. FIG 2 comprises blocks representing certain vehicle and/or system 200 components. FIG 2 also shows arrows connecting the blocks. The arrows represent the path of electrical and mechanical (torque) energy through the system 200 when the vehicle is being driven. The energy is produced by the internal combustion engine 105.

The mechanical drive line means 201 begins at a portion receiving torque from the internal combustion engine 105. In the example of FIG 2, but not necessarily all examples, the torque follows a path through the mechanical drive line means 201, first through a transfer case 216 and then through a rigid front drive shaft 218 rotatable about its length axis, substantially aligned with the longitudinal axis 102. The torque path then enters differential means 219.

The differential means 219 is for controlling the distribution of torque between the first vehicle wheel 101 and the second vehicle wheel 107. The differential means 219 may enable torque vectoring so that torque can be unevenly distributed to the vehicle wheels.

In the example of FIG 2 the differential means 219 comprises mechanical differential means 219 which is part of the mechanical drive line means 201.

The mechanical differential means 219 in FIG 2 is positioned, within the system 200, to be located on the first side 103, i.e. left or right side, of the vehicle 100. As the mechanical differential means 219 and first vehicle wheel 101 are on the same side 101 of the vehicle 100 without obstruction by the internal combustion engine 105, the first vehicle wheel axle 215 is directly mechanically coupled to a first output of the differential means 219. The first vehicle wheel axle 215 is rigid and rotatable about its length axis.

In the example of FIG 2, but not necessarily all examples, the torque path also continues from a second output of the differential means 219 opposite the first output, towards the second vehicle wheel 107, by means of any suitable rigid mechanical component rotatable about its length axis. However, the internal combustion engine 105 forms an obstruction making it impossible for the rotatable rigid mechanical component to act as a transverse intermediate drive shaft passing under or around the internal combustion engine 105 to the second side 109 of the vehicle 100, opposite the first side 103. Therefore, the mechanical component of the mechanical drive line means 201 terminates adjacent the internal combustion engine 105.

The system 200 comprises electrical drive line means 203 to transmit torque to the second vehicle wheel 107 on the second side 109 of the vehicle 100. The electrical drive line means 203 enables the second vehicle wheel 107 to be driven despite the absence of a mechanical linkage between the second vehicle wheel 107 and the internal combustion engine 105.

The consequence is that the first vehicle wheel 101 is mechanically driven, i.e. directly mechanically connected to the output of the internal combustion engine 105, and the second vehicle wheel 107 is exclusively electrically driven, i.e. driven by, for example, an electric motor.

In the example of FIG 2, the system 200 comprises two separated electric machines 207, 209. The electric machines 207, 209 may have identical structure. The electric machines 207, 209 are electrically coupled by, for example, an electrical cable 211 of the electrical drive line means 203, which may be flexible.

The electric machines 207, 209 comprise a first electric machine 207 and a second electric machine 209. The first electric machine 207 acts as an interface between the mechanical drive line means 201 and the electrical drive line means 203. The second electric machine 209 acts as an interface between the electrical drive line means 203 and the second vehicle wheel 107, optionally via a second vehicle wheel axle 217.

In a first operating scenario the first electric machine 207 is arranged to generate electrical energy from rotation of a portion 205 of the mechanical drive line means 201 and acts as an electric generator, and the second electric machine 209 is electrically coupled to the first electric machine 207 and acts as an electric motor. The electrical cable 211 provides the electrical energy to the second electric machine 209. The second electric machine 209 drives the second vehicle wheel 107 using the electrical energy. The first operating scenario relates to a scenario in which positive torque generated by the internal combustion engine 105 exceeds subtractive torque generated by the second vehicle wheel 107.

It would be appreciated that a second operating scenario is possible in which the first electric machine 207 acts as an electric motor and the second electric machine 209 acts as an electric generator. The second operating scenario relates to a scenario in which subtractive torque generated by the second vehicle wheel 107 exceeds positive torque generated by the internal combustion engine 105, for example during hill descent.

In the example of FIG 2, the electric coupling between the first electric machine 207 and the second electric machine 209 is provided by at least the electrical cable 211. The electrical cable 211 may comprise insulation wrapped around at least one conductive core. The electrical cable 211 may be flexible along at least part of its length. The electrical cable 211 may have an outside diameter determined by the power required by the electric machine, for example less than 3 cm.

The first electric machine 207 is arranged to generate electricity from rotation of a portion 205 of the mechanical drive line means 201 mechanically coupled to the second output of the mechanical differential means 219. The second electric machine 209 is arranged to electrically drive the second vehicle wheel 107 using electricity generated by the first electric machine 207. Therefore, it would be appreciated that the system 200 is configured to enable the second vehicle wheel 107 to be electrically driven using electrical energy generated from the mechanical drive line means 201 at the same time as the first vehicle wheel 101 is mechanically driven by the internal combustion engine 105.

In FIG 2, the arrows between the first electric machine 207 and second electric machine 209 represent a flow of electrical energy through the electrical cable 211, and also represent an example physical path taken by the electrical cable 211.

In the figures the directions of the arrows suggest a flow of energy in a particular direction. This relates to the first operating scenario. It would be appreciated that energy may flow in the opposite direction in the second operating scenario.

The electrical drive line means 203 is positioned, within the system 200, to avoid obstruction by the internal combustion engine 105.

The first electric machine 207 is positioned, within the system 200, to be located on the first side 103 of the vehicle 100, and the second electric machine 209 is positioned, within the system 200, to be located on the second side 109 of the vehicle 100. The internal combustion engine 105 is situated between the first electric machine 207 and second electric machine 209.

The first electric machine 207 may be positioned at any suitable location on the mechanical drive line means 201, for example at a location where rotation of the mechanical drive line means 201 driven by torque output from the internal combustion engine 105 can be converted to electrical energy by the first electric machine 207.

In some, but not necessarily all examples, the first electric machine 207 is positioned, within the system 200, such that an axis of rotation 213A of a first vehicle wheel 101 passes through the first electric machine 207, and/or an axis of rotation 213A’ of a first vehicle wheel axle 215 for driving the first vehicle wheel 101 passes through the first electric machine 207.

In some, but not necessarily all examples, the second electric machine 209 is positioned, within the system 200, such that an axis of rotation 213B of the second vehicle wheel 107 passes through the second electric machine 209, and/or an axis of rotation 213B’ of a second vehicle wheel axle 217 for driving the second vehicle wheel 107 passes through the second electric machine 209.

In some, but not necessarily all examples, the first electric machine 207 and second electric machine 209 are positioned, within the system 200, to be at a same longitudinal position within the vehicle 100.

The first electric machine 207 and second electric machine 209 may be separated by a transverse distance, for example, 75 cm. In other examples the separation may be within the range 50 cm to 100 cm. The electrical cable 211 has sufficient span to reach between the first electric machine 207 and second electric machine 209. A region 214 is provided within the system 200. The region 214 is for receiving at least part of the internal combustion engine 105. The region 214 is an empty space within the system 200 able to accommodate a whole or a substantial part of the internal combustion engine 105.

The region 214 is located such that one or more of the following axes passes through the region 214: the axis of rotation 213A of the first vehicle wheel 101; the axis of rotation 213B of the second vehicle wheel 107; the axis of rotation 213A’ of the first vehicle wheel axle 215; the axis of rotation 213B’ of the second vehicle wheel axle 217.

In some, but not necessarily all examples, the electrical drive line means 203 diverts around the region 214. The first electric machine 207 and second electric machine 209 are positioned outside the region 214. The electrical cable 211 extends along at least part of the periphery of the region 214. The electrical cable 211 may define at least part of the boundary of the region 214. The electrical cable 211 extends at least partially along and offset from one or more of the above-mentioned axes 213A, 213A’, 213B, 213B’.

An example of the path of the electrical cable 211 is illustrated in FIG 2. In this example, but not necessarily all examples, the electrical cable 211 extends in a first longitudinal direction towards the front of the vehicle and away from the internal combustion engine 105, then in a transverse direction in front of the internal combustion engine 105, and then in a second longitudinal direction opposite the first longitudinal direction. In other examples the electrical cable 211 may extend behind, under or over the internal combustion engine 105.

The system 200, in particular the electrical drive line means 203 is therefore arranged to avoid the obstruction without the need for a transverse intermediate drive shaft passing under the internal combustion engine 105.

The electrical cable 211 is arranged to supply electrical energy to cause the second electric machine 209 to electrically drive the second vehicle wheel 107.

In some, but not necessarily all examples, the second electric machine 209 rotates the second vehicle wheel axle 217, which in turn rotates the second vehicle wheel 107. The second vehicle wheel axle 217 differs from the first vehicle wheel axle 215 in that the second vehicle wheel axle 217 is mechanically decoupled from the mechanical drive line means 201. The second vehicle wheel axle 217 is therefore not part of the mechanical drive line means 201. The second vehicle wheel axle 217 is driven exclusively by the second electric machine 209.

The second vehicle wheel axle 217 would not be required if the second electric machine 209 is a wheel hub electric machine for mounting within the hub of the second vehicle wheel 107. The lack of separation between the wheel hub electric machine and the second vehicle wheel 107 obviates the need for a conventional axle 217.

Referring now to the first electric machine 207 and second electric machine 209 in more detail, the first electric machine 207 and/or second electric machine 209 may be a switched reluctance electric machine. FIG 6 shows an example switched reluctance machine, labelled as the first electric machine 207; however the second electric machine 209 may have identical structure to the first electric machine 207. The example structure of FIG 6 may be used in some or all of the examples described in this application.

According to the example in FIG 6, the switched reluctance machine comprises a solid salient-pole rotor 601 having projecting magnetic poles 603. The rotor 601 may comprise soft magnetic material. The rotor 601 material may comprise laminated steel. The switched reluctance electric machine also comprises stator poles 605 comprising electrical windings.

Any suitable portion 205 of a rotatable shaft of the mechanical drive line means 201 may comprise the rotor 601 for the first electric machine 207. In some, but not necessarily all examples, the portion 205 is a section of the first vehicle wheel axle 215. In other examples the portion 205 may be a section of the front drive shaft 218. The rotor 601 comprises the magnetic poles 603 projecting radially outwardly from the axis of rotation of the portion 205.

Regarding the second electric machine 209, a rotatable rigid component or shaft, arranged to rotate the second vehicle wheel 107, may comprise a rotor 601. In some, but not necessarily all examples, the second vehicle wheel axle 217 comprises the rotor 601.

With reference to FIG 6, when power is applied to windings on the stator poles 605, the rotor’s 601 magnetic reluctance creates a force that attempts to align each rotor pole 603 with the nearest stator pole 605. In order to maintain rotation, an electronic control system 607 switches on the windings of successive stator poles in sequence so that the magnetic field of the stator ‘leads’ the rotor pole, pulling it forward. An electronic position sensor 609 determines the angle of the rotor shaft.

The first electric machine 207 acts as an interface between the mechanical drive line means 201 and the electrical drive line means 203. This is because the first electric machine 207 of FIG 6 comprises components of the mechanical drive line means 201 and components of the electrical drive line means 203. For example the mechanical drive line means 201 comprises at least the portion 205 of the rotatable shaft, as well as the rotor 601, and the electrical drive line means 203 comprises the stator poles 605 because they generate electrical energy from rotation of the rotor 601.

For similar reasons, the second electric machine 209 acts as an interface between the electrical drive line means 203 and the second vehicle wheel 107. The electrical drive line means 203 comprises stator poles 605 which carry electrical energy, but not the second vehicle wheel 207 or the second vehicle wheel axle 217 because the latter rotate to transmit mechanical energy.

The above-described system 200 may be operable at any time whilst torque is to be transmitted to the first vehicle wheel 101 and to the second vehicle wheel 107. In some, but not necessarily all examples, the vehicle 100 has an all-wheel drive mode enabling torque to be transmitted to the first vehicle wheel 101 and to the second vehicle wheels 107 when the all-wheel drive mode is active. The system 200 is non-operational when the all-wheel drive mode is inactive.

The vehicle 100 may comprise means 106, such as a controller 106, for disengaging drive of the first vehicle wheel 101 and second vehicle wheel 107, for instance causing disengagement of the all-wheel drive mode described above. Such disengagement would cause the system 200 to become non-operational. In some, but not necessarily all examples, disengagement may occur in the event of a detected failure of the electrical drive line means 203. The means 106 may be electronic or mechanical and the disengagement is performed automatically if a failure condition is detected. In some examples the disengagement is performed by a clutch in the transfer case 216 or a clutch in the front drive shaft 218. The vehicle would continue to be driven by other vehicle wheels different from the first vehicle wheel 101 and the second vehicle wheel 107. In other examples the front vehicle wheels may also be disengaged to reduce frictional losses in the drivelive when all wheel drive traction is not required. All wheel drive traction may only be required for safety and stability of the vehicle 100.

In some, but not necessarily all examples, the all-wheel drive mode enables the majority of torque to be transmitted to the rear wheels, the remaining torque being transmitted to the front wheels comprising the first vehicle wheel 101 and second vehicle wheel 107. An example torque split is 80% to the rear, 20% to the front. The differential means 219 may send 10% torque for mechanical driving of the first vehicle wheel 101, and 10% torque for electrical driving of the second vehicle wheel 107. In some circumstances the split may be unequal. When the all-wheel drive mode is inactive, the torque split may be 100% to the rear, 0% to the front. FIG 3 illustrates another example of the system 200. Several aspects of the system 200 of FIG 3 are similar to the system 200 of FIG 2. For instance the first vehicle wheel axle 215, first electric machine 207, second electric machine 209, transfer case 216, front drive shaft 218, engine bay 111, means 106 for disengagement, second vehicle wheel axle 217, axes of rotation 213A, 213A’, 213B, 213B’ and region 214 for receiving the internal combustion engine 105 are as described in relation to the system 200 of FIG 2, and are labelled in FIG 3.

The system 200 in FIG 3 does not comprise mechanical differential means 219. The front drive shaft 218 connects to the first vehicle wheel axle 215 via a simple non-differential bevel gearbox 220.

The system 200 in FIG 3 comprises a different differential means 219 from the differential means of the system 200 of FIG 2. In FIG 3 the differential means 219 comprises electrical differential means 219 in which the functionality of a mechanical differential is provided by electrical components of the electrical drive line means 203 carrying electrical energy, rather than rotating components of the mechanical drive line means 201 carrying mechanical energy. This is described in more detail below.

In other examples both electrical differential means 219 and mechanical differential means 219 are included which together provide the differential means 219.

The system 200 of FIG 3 comprises an electrical energy storage device 301 comprised as part of the electrical drive line means 203. The electrical energy storage device 301 is selectably electrically coupled to the first electric machine 207 and to the second electric machine 209. The electrical energy storage device 301 is electrically coupled to the electrical cable 211. In the example of FIG 3, the electrical energy storage device 301 comprises at least one capacitor 301 and/or other suitable electrical energy storage device 301, e.g. battery.

In the example of FIG 3, but not necessarily all examples, the system 200 comprises selectable bypass means 303 external to the electrical energy storage device 301 to enable electrical bypassing of the electrical energy storage device 301. In the example of FIG 3, the selectable bypass means 303 comprises an electrical switch having a first switching state in which electric current flows indirectly between the first electric machine 207 and second electric machine 209, via at least the electrical energy storage device 301, and a second switching state in which electric current flows between the first electric machine 207 and second electric machine 209, following a bypass path bypassing the electrical energy storage device 301. In some examples one or more electrical components, such as power electronics for controlling bi-directional power flow, is provided in the bypass path.

In the example of FIG 3, the electrical energy storage device 301 and selectable bypass means 303 are controllable by a controller 307 to provide electrical differential means 219.

The controller 307 is programmed, for example, to perform a method of electronically providing a differential for a vehicle 100, wherein the first vehicle wheel 101 on the first side 103 of the vehicle 100 is arranged to be mechanically driven by the mechanical drive line means 201 mechanically connected to the internal combustion engine 105, wherein the second different vehicle wheel 107 on the second different side 109 of the vehicle 100 is arranged to be simultaneously electrically driven by the electrical drive line means 203 using electrical energy generated from the mechanical drive line means 201, the method comprising: determining that at least the second vehicle wheel 107 is slipping; and in response to the determination, enabling the electrical energy storage device 301 comprised in the electrical drive line means 203 to store electrical energy within the electrical energy storage device 301.

The determination that at least the second vehicle wheel 107 is slipping is made by the controller 307 in dependence on analyzing inputs from one or more sensors 305. The sensors 305 may be vehicle wheel speed sensors 305. Vehicle wheel speed sensors 305 are arranged to measure the speeds of at least the first vehicle wheel 101 and the second vehicle wheel 107. Other sensor inputs may be analyzed to produce the determination, such as torque information from one or more torque sensors, drive shaft rotation information from one or more drive shaft sensors, or engine rotation information.

Enabling the electrical energy storage device 301 to store electrical energy may comprise disabling electrical bypassing, or enabling electrical connection, of the electrical energy storage device 301, so that the electrical energy storage device 301 is closed circuit with the first electric machine 207 and second electric machine 209. The electrical energy storage device 301 is then able to electrically charge such that a greater proportion of torque produced by the combustion engine 105 is used to charge the electrical energy storage device 301, therefore reducing the torque available for driving at least the slipping second vehicle wheel 107. When vehicle wheel slip is not detected, electrical bypassing of the electrical energy storage device 301 may be enabled by the controller 307.

The controller 307 may be further programmed to determine that the first vehicle wheel 101 is slipping; and in response to the determination, enable an electrical energy storage device 301 electrically connected to the electrical drive line means 203 to store or release electrical energy within the electrical energy storage device 301. In some examples a greater proportion of torque produced by the internal combustion engine 105 charges the electrical energy storage device 301, therefore reducing the torque available for driving at least the slipping first vehicle wheel 101.

In the example of FIG 3, charging and discharging the electrical energy storage device 301 provides a form of torque vectoring. It would be undesirable to provide torque to drive a slipping one of the first vehicle wheel 101 and the second vehicle wheel 107, so torque is converted to electrical energy stored by the electrical energy storage device 301 at least temporarily.

The ability of the electrical energy storage device 301 to hold charge provides a further opportunity for vehicle control. The electrical energy storage device 301 and selectable bypass means 303 may be controllable by the controller 307 to provide the functionality of a temporary torque boosting means to boost acceleration of the vehicle 100.

The controller 307 may be programmed, for example, to perform a method of boosting torque of the vehicle 100, wherein while the first vehicle wheel 101 on the first side 103 of the vehicle 100 is mechanically driven by the mechanical drive line means 201 mechanically connected to the internal combustion engine 105, the method comprises: discharging the electrical energy storage device 301 comprised in the electrical drive line means 203 to electrically drive the second different vehicle wheel 107 on the second different side 109 of the vehicle 100.

The torque boost means that while the internal combustion engine 105 provides torque for mechanically driving at least the first vehicle wheel 101, the electrical energy storage device 301 is able to supply torque for electrically driving the second vehicle wheel 107. The combination of two sources of energy operating together raises the maximum torque which the vehicle 100 can produce.

The torque boost may last for as long as the electrical energy storage device 301 has charge. The charge may have been supplied via operation of the electrical differential means 219 described above in relation to FIG 3 or via operation of other electrical generators on the vehicle. In some examples, one or more electrical components such as inverters may be supplied to the electrical energy storage device 301 to allow for ac / dc switching. Further power electronics might be incorporated to increase functionality such as enabling the charge to be supplied by external electric power sources in the manner of a hybrid or electric vehicle, or by regenerative braking.

The above described electrical differential means 219 obviates the need for mechanical differential means 219 as described in FIG 2. In FIG 3 the first electric machine 207 is positioned to be on the first vehicle wheel axle 215 itself, rather than FIG 2 in which the mechanical differential means 219 comprises separate first and second outputs for the first vehicle wheel axle 215 and the first electric machine 207. Therefore torque for both vehicle wheels is provided by the front drive shaft 218 to the first vehicle wheel axle 215. The first vehicle wheel axle 215 may be sized to accommodate torque for both vehicle wheels. The first vehicle wheel axle 215 may have a greater thickness than a second vehicle wheel axle 217, and/or may comprise a stronger material. FIG 4 Illustrates another example of the system 200. Several aspects of the system 200 of FIG 3 are similar to the system 200 of FIG 2 and FIG 3. For instance the first vehicle wheel axle 215, first electric machine 207, second electric machine 209, controller 307, transfer case 216, front drive shaft 218, engine bay 111, means 106 for disengagement, second vehicle wheel axle 217, axes of rotation 213A, 213A’, 213B, 213B’ and region 214 for receiving the internal combustion engine 105 are as described in relation to the systems 200 of FIG 2 and FIG 3 and are labelled in FIG 4. FIG 4 illustrates a hybrid electric vehicle 100 in which the second vehicle wheel 107 is exclusively electrically driven by an electrical energy storage device 401 in the form of a battery 401. The battery 401 is electrically coupled to the first electric machine 207 and second electric machine 209. In the example of FIG 4, the battery 401 is electrically coupled to the electrical cable 211. One or more electrical inverters 403A, 403B may be electrically coupled to the battery 401 and electrical cable 211.

In some, but not necessarily all examples, the controller 307 of the battery 401 provides at least some of the functionality of the controller 307 as described in relation to FIG 3. In some, but not necessarily all examples, the electrical energy storage device 401 comprise selectable bypass means (not shown) internal to the device 401 which may operate in a similar manner to the selectable bypass means 303 described in relation to FIG 3.

The electrical differential means 219 may be provided by the electrical energy storage device 401 controlled by the controller 307. In other examples the differential means 219 is a mechanical differential means 219 as described in relation to FIG 2. In other examples both electrical differential means 219 and mechanical differential means 219 are included which together provide the differential means 219.

For purposes of this disclosure, it is to be understood that the controller(s) 307 described herein can each comprise a control unit or computational device having one or more electronic processors. A vehicle 100 and/or a system 200 thereof may comprise a single control unit or electronic controller or alternatively different functions of the controller(s) may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s)). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processor(s). For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computer-readable storage medium (e.g., a non-transitory storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

It has been described above that the system 200 enables the internal combustion engine 105 to sit lower in the vehicle. FIG 5 illustrates an example vehicle 100 comprising the internal combustion engine 105. FIG 5 also shows the axis of rotation 213A of the first vehicle wheel 101, the axis of rotation 213B of the second vehicle wheel 107, the axis of rotation 213A’ of the first vehicle wheel axle 215 and the axis of rotation 213B’ of the second vehicle wheel axle 217. The lowest point of the internal combustion engine 105 may be below one or more of these axes of rotation. A centre of gravity 501 of the powertrain, in some examples the internal combustion engine 105, may be below one or more of these axes of rotation, or above in other examples.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A system for a drive line of a vehicle, the system comprising: mechanical drive line means enabling a first vehicle wheel, on a first side of the vehicle, to be mechanically driven by a combustion engine; and electrical drive line means enabling a second different vehicle wheel, on a second different side of the vehicle, to be electrically driven using electrical energy generated from the mechanical drive line means.

2. A system as claimed in claim 1, wherein the system is arranged to enable the second vehicle wheel to be electrically driven using electrical energy generated from the mechanical drive line means at the same time as the first vehicle wheel is mechanically driven by the combustion engine.

3. A system as claimed in any preceding claim, wherein the electrical drive line means comprises at least an electrical cable electrically coupling a first electric machine to a second electric machine, wherein the first electric machine is electrically coupled to a portion of the mechanical drive line means.

4. A system as claimed in claim 3, wherein the first electric machine is positioned, within the system, to be located on the first side of the vehicle, and wherein the second electric machine is positioned, within the system, to be located on the second side of the vehicle.

5. A system as claimed in claim 3 or 4, wherein an axis of rotation of the second vehicle wheel and/or an axis of rotation of a second vehicle wheel axle for driving the second vehicle wheel passes through the second electric machine.

6. A system as claimed in claim 3, 4 or 5, wherein an axis of rotation of a first vehicle wheel axle for driving the first vehicle wheel and/or an axis of rotation of the first vehicle wheel passes through the first electric machine.

7. A system as claimed in any preceding claim, wherein the electrical drive line means diverts around a region for receiving at least part of the combustion engine.

8. A system as claimed in any preceding claim, comprising one or more switched reluctance machines.

9. A system as claimed in any preceding claim, comprising a wheel hub electric machine.

10. A system as claimed in any one of claims 1 to 8, comprising a second vehicle wheel axle for driving the second vehicle wheel, wherein the second vehicle wheel axle is mechanically decoupled from the mechanical drive line means.

11. A system as claimed in any preceding claim, wherein a portion of the mechanical drive line means and/or a rotatable rigid component or shaft arranged to rotate the second vehicle wheel comprises magnetic poles projecting radially outwardly from an axis of rotation in a rotor formation.

12. A system as claimed in any preceding claim, wherein the mechanical drive line means and/or the electrical drive line means comprises differential means configured to enable torque vectoring for the first vehicle wheel and second vehicle wheel.

13. A system as claimed in any preceding claim, wherein the electrical drive line means comprises an electrical energy storage device.

14. A system as claimed in claim 13, wherein the electrical drive line means comprises selectable bypass means to enable electrical bypassing of the electrical energy storage device.

15. A system as claimed in claim 13 or 14, wherein the electrical energy storage device comprises a capacitor or a battery.

16. A system as claimed in any preceding claim, wherein the first vehicle wheel and the second vehicle wheel are front wheels of the vehicle.

17. A system as claimed in any preceding claim, wherein the mechanical drive line means is configured to enable mechanical driving of all of the vehicle wheels of the vehicle apart from the second vehicle wheel.

18. A system as claimed in any preceding claim, wherein the combustion engine comprises more than four internal combustion cylinders arranged in a line parallel to a forward direction of motion of the vehicle.

19. A vehicle comprising the system as claimed in any preceding claim.

20. A method of electronically providing a differential for a vehicle, wherein a first vehicle wheel on a first side of the vehicle is arranged to be mechanically driven by mechanical drive line means mechanically connected to a combustion engine, wherein a second different vehicle wheel on a second different side of the vehicle is arranged to be simultaneously electrically driven by electrical drive line means using electrical energy generated from the mechanical drive line means, the method comprising: determining that at least the second vehicle wheel is slipping; and in response to the determination, enabling an electrical energy storage device comprised in the electrical drive line means to store electrical energy within the electrical energy storage device.

21. A method of boosting torque of a vehicle, wherein while a first vehicle wheel on a first side of the vehicle is mechanically driven by mechanical drive line means mechanically connected to a combustion engine, the method comprises: discharging an electrical energy storage device comprised in electrical drive line means to electrically drive a second different vehicle wheel on a second different side of the vehicle.

22. A method as claimed in claim 20 or 21, wherein the energy storage device comprises a capacitor or a battery.

23. A controller comprising means configured to perform the operations of the method of any one or combination of claims 20 to 22.

24. A system, a method, a vehicle or controller as hereinbefore described with reference to the accompanying drawings.