Vehicle and Suspension Arm Assembly

A vehicle (8) comprising a vehicle body (81), a ground-engaging wheel (7), a suspension arm (1) by means of which the wheel (7) is mounted on the vehicle body (81), an electric motor/generator (2) with a mechanical driveline by means of which the motor/generator (2) is connected to the wheel (7) such that rotation of the wheel (7) about a wheel axis (B) may be driven by the motor (2) or rotation of the wheel may drive the generator (2), wherein the motor/generator (2) is mounted on the suspension arm (1).

The present invention relates to vehicle, particularly to a vehicle with an independent electric drive system suitable for low floor commercial vehicles capable of autonomous operation, and a suspension arm assembly suitable for use in such a vehicle.

BACKGROUND

It is known to drive vehicles, includings commercial light and heavy goods vehicles, using one or more electric motors. In current electric vehicles, the electric motor is mounted either on the axle beam or integrated into the wheel hub. This means the motor or motors have to be installed under the floor of the vehicle which, since vehicles have a limited height, limits the cubic capacity of goods receiving compartment of the vehicle.

The present invention may assist in improving the capacity of the goods receiving compartment of an electrically driven commercial goods vehicle.

SUMMARY

The disclosed technology allows the space surrounding the vehicle wheels to mount an electric motor on the suspension arm. This suspension arm houses a mechanical drive connecting electric motor to the vehicle axle wheel hub so that each wheel can be driven independently by an electric drive. The motor can also be used as a generator to regenerate energy. Mounting the motor on the suspension arm allows for an extremely low floor height, which can either be used to provide increased load capacity, or to reduce drag, or combination of the two.

According to a first aspect of the disclosed technology we provide a vehicle comprising a vehicle body, a ground-engaging wheel, a suspension arm by means of which the wheel is mounted on the vehicle body, an electric motor/generator with a driveline by means of which the motor/generator is connected to the wheel such that rotation of the wheel about a wheel axis may be driven by the motor or rotation of the wheel may drive the generator, wherein the motor/generator is mounted on the suspension arm.

By virtue of the invention, the wheel motor/generator installation may not significantly constrain the floor height.

In one embodiment, the suspension arm has a first portion which is pivotally connected to the vehicle body and a second portion which is connected to the vehicle body via a spring.

The spring may be an air-spring.

In one embodiment, the electric motor/generator is mounted on the suspension arm between the first portion and the second portion.

In one embodiment, the electric motor/generator is mounted on a third portion of the suspension arm which is offset relative to a line between the first portion and the second portion.

In one embodiment, the vehicle is further provided with a wheel hub assembly, by means of which the wheel is mounted on the suspension arm1, the wheel hub assembly being mounted on the same side of the suspension arm as the electric motor/generator. The electric motor/generator is advantageously located so that it is higher than the wheel axis. The electric motor/generator may be mounted above the wheel hub assembly. In one embodiment, the electric motor/generator is mounted directly above the centreline of the wheel.

The wheel hub assembly may comprise at least one epicyclic gear train.

The driveline may comprise a gear train, belt, chain, drive shaft with bevel gears or a combination of one or more of a gear train, belt, chain, drive shaft with bevel gears.

The driveline may be mounted on and or integrated with the suspension arm.

The driveline may be connected to a brake disc, a wheel hub or an adaptor plate.

In one embodiment, the vehicle comprises a pair of ground engaging wheels, and a pair of suspension arms by means of which the wheels are mounted on the vehicle body, one wheel being mounted each suspension arm, there being an electric motor/generator mounted on each suspension arm, each suspension arm being further provided with a mechanical driveline by means of which the motor/generator is connected to the wheel mounted on the suspension arm in question such that rotation of the wheel may be driven by the motor or rotation of the wheel may drive the generator. In this case, each suspension arm may have a first portion which is pivotally connected to the vehicle body and a second portion which is connected to the vehicle body via a spring, and each suspension arm being unconnected to each other so that each can pivot relative to the vehicle body independently of the other. Alternatively, the pair of suspension arms may be connected to each other by an axle beam which is longitudinally and vertically offset relative to the wheel axis of each of the wheels. By virtue of this longitudinal and vertical offset, such that it will allow axle beam to move under the extremely low floor height.

In one embodiment, the pair of suspension arms can be used as a single pair or in multiple axle configuration.

In one embodiment, the or each motor is operable to drive the vehicle.

In one embodiment, the motor/generator is operable to convert kinetic energy derived from rotation of the wheel or wheels to electrical energy. In this case, the vehicle may be provided with an electrical energy storage apparatus, such as a battery, which is connected to the motor/generator so that the electrical energy generated by the motor/generator may be stored in the electrical energy storage apparatus. The electrical energy generated by the motor/generator may be used to power on-board equipment including but not limited to Transport Refrigeration Units.

According to a second aspect of the disclosed technology we provide a vehicle comprising a tractor and a trailer or semi-trailer, the trailer/semi-trailer having all the features of the vehicle according to the first aspect of the invention, wherein the trailer/semi-trailer is connected to the tractor so that it can be towed by the tractor, and the tractor is provided with a drive apparatus which is operable to drive the tractor, the or each motor of the trailer being operable to either assist the drive apparatus of the tractor in driving the vehicle or to be operated instead of the drive apparatus to drive the vehicle without use of the drive apparatus of the tractor.

According to a third aspect of the disclosed technology we provide a vehicle suspension arm assembly comprising a suspension arm with first portion by means of which the arm can be pivotally connected to a vehicle body, a second portion on which is mounted a spring, the assembly further comprising an electric motor/generator, a wheel hub assembly having a wheel mount on which a wheel may be mounted, and a driveline which connects the motor/generator to the wheel hub assembly such that rotation of the wheel mount about a wheel axis may be driven by the motor or rotation of the wheel mount may drive the generator, wherein the motor/generator, wheel hub assembly and driveline are mounted on the suspension arm and the motor/generator and wheel hub assembly are on the same side of the suspension arm.

By virtue of mounting the motor/generator and wheel hub assembly on the same side of the suspension arm, the suspension arm can be arranged such that the suspension arm lies in a generally vertical plane with the motor/generator above the wheel hub assembly.

In one embodiment, the wheel hub assembly is mounted on an intermediate portion of the suspension arm which is between the first portion and second portion of the suspension arm. In this case the intermediate portion may be offset relative to a line connecting the first portion and second portion.

The wheel hub assembly may comprise at least one epicyclic gear train which is connected between the wheel mount and the mechanical driveline to transmit a drive torque between the mechanical driveline and the wheel mount. The epicyclic gear train may comprise a sun gear which is connected to the mechanical driveline so that the mechanical driveline drives or is driven by rotation of the sun gear. The epicyclic gear train may comprise a planet gear which meshes with the sun gear and which is supported by a carrier, the carrier being connected to the wheel mount such that rotation of the wheel mount is driven by or drives rotation of the carrier.

The motor/generator may mounted on the suspension arm between the first portion and second portion. The motor/generator may be mounted on a third portion of the suspension arm which is offset relative to a line between the first portion and second portion. The third portion may be connected to the intermediate portion by means of a driveline support portion of the suspension arm, the driveline being mounted on the driveline support portion.

DETAILED DESCRIPTION

The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, “upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader's convenience only and shall not be limiting.

Referring now toFIGS.1,2,3and4, there is shown the overall arrangement of an embodiment of suspension arm assembly suitable for use in a vehicle according to the first and second aspects of the invention. The suspension arm assembly comprises a suspension arm1, on which is mounted an electric motor/generator2. The electric motor/generator is, in this embodiment, mounted on the suspension arm1via a gearbox21. The provision of such a gear box is not essential, however. The motor/generator2is a conventional electric motor/generator and has a rotor (not shown) which rotates about a motor axis A.

The suspension arm assembly is also provided with a wheel hub assembly3, which can rotate relative to the suspension arm1about a wheel axis B, and by means of which a ground engaging wheel may be mounted on the suspension arm1. In this embodiment, the wheel axis B is generally parallel to the motor axis A. The wheel hub assembly3is described in more detail below.

The suspension arm assembly is also provided with a driveline by means of which the motor/generator2is connected to the wheel hub assembly3so that when used as a motor, operation of the motor/generator2drives rotation of the wheel hub assembly3, and therefore rotation of a wheel mounted on the wheel hub assembly, about the wheel axis B, and enables the motor/generator2to act as a generator to convert kinetic energy from the rotating wheel into electrical energy. In this embodiment, the driveline is configured such that the wheel axis B is generally parallel to motor axis A. Various configurations of mechanical driveline can be used, as will be described in more detail below.

The motor/generator2and wheel hub assembly3are mounted on the same side of the suspension arm1. Consequently, if one considers that the wheel hub assembly3is located between two parallel imaginary planes, with the suspension arm1lying in one of the these planes, the motor/generator2also extends from the suspension arm1into the space between these two imaginary planes.

The suspension arm1has a first portion1awhich is provided with a bush11by means of which the suspension arm1may be pivotally mounted on a vehicle body so that the suspension arm1is rotatable relative to vehicle body about a pivot axis C, which is generally parallel to the wheel axis B.

The suspension arm1has a second portion1bon which is mounted a spring4. The spring4is configured to be connected to the vehicle body, so that the second portion of the suspension arm1is connected to the vehicle body via the spring4, the spring4extending and compressing when the suspension arm pivots about the bush11. In one embodiment, the spring4is an air spring. It could equally be a helical compression spring, or any other suitable form of suspension spring.

In this example, the air spring has a piston41on which are mounted brackets42and43which are rigidly mounted on the second portion1bof the suspension arm1via a spring shaft43. The spring shaft43has a longitudinal axis D which is generally parallel to the pivot axis C.

In this embodiment, the spring4is mounted on the same side of the suspension arm1as the motor/generator2and the wheel hub assembly3. Consequently, the spring4is also located in the space between the imaginary planes mentioned above.

In this embodiment, the wheel hub assembly3is mounted on an intermediate portion1cof the suspension arm1which is between the first and second portions1a,1b.

The first, second and intermediate portions1a,1b,1cof the suspension arm could be linear so that the pivot axis C, the spring shaft axis D, and the wheel axis B are all arranged along a generally straight line. This is not the case in this embodiment, however, and the first portion1aof the suspension arm1is bent so that the wheel axis B is offset from a line connecting the pivot axis C and the spring shaft axis D.

Whilst the motor/generator2could be mounted on either the first or second portions1a,1bof the suspension arm1, with the driveline extending along the first or second portion1a,1bto the intermediate portion1c, in this embodiment the motor/generator2is mounted on a third portion1dof the suspension arm1cwhich lies between the first portion1aand the second portion1b, but which is offset from a line joining first portion1ato the second portion1b. The third portion1dof the suspension arm1is connected to the intermediate portion1cby a driveline support portion1e, along which the driveline extends to connect the motor/generator2to the wheel hub assembly3.

Although not essential, in this embodiment, to enhance the stability of the suspension arm1, the suspension arm1also includes a support strut1fwhich extends from the second portion1bto the third portion1d. The driveline support portion1e, support strut1fand second portion1bof the suspension arm1thus form a triangle, with the motor axis A, the wheel axis B and the spring shaft axis D at the three corners of the triangle.

Although not essential, in this embodiment, the suspension arm assembly is also provided with a damper6which has a first end which is pivotally connected to the suspension arm1, and a second end which is, in use, pivotally connected to the vehicle body. In this embodiment, the first end of the damper6is pivotally connected to the motor/generator2, although it will be appreciated that it could be connected to any other convenient point on the suspension arm1.

The damper6is configured to dampen oscillation of the suspension arm1when the vehicle is in use, as is conventional in air suspension systems, and may comprises a hydraulic piston and cylinder, or any other conventional form of suspension damper.

In use, the points of connection between the vehicle body and the first portion1aof the suspension arm1and the spring4are arranged such that the wheel hub moves generally vertically as the spring4extends or compresses. In other words, the orientation of the air spring4along with the damper6which is connected between the vehicle body and the suspension arm1is such that the spring41provides vertical control to the suspension arm1.

In this embodiment, in use, the suspension arm1is arranged as illustrated inFIG.4, such that the first portion1ais the lowest part, the intermediate and second portions1c,1bbeing displaced horizontally, and vertically with respect to the first portion1a. The wheel axis B therefore lies between the pivot axis C and the spring shaft axis D in both a vertical and horizontal direction, and the wheel axis B, and spring shaft axis D are higher than the pivot axis C.

The suspension arm1is also arranged such that the driveline support portion1eextends upwardly from the intermediate portion1c, so that the motor axis A is higher than the wheel axis B. Whilst the motor axis A could be directly above the wheel axis B, in this embodiment, the motor/generator2is slightly closer, in the horizontal direction, to the pivot axis C than the wheel axis B, but is higher than the top of a wheel7mounted on the wheel hub assembly3. It should be appreciated that the suspension arm1could be configured so that the motor/generator2is located with the motor axis A anywhere in a semi-circular arc extending from and above the wheel axis B. The suspension arm1could, for example, be configured so that the wheel axis B is closer to the pivot axis C than the motor axis A. Moreover, the suspension arm1could be configured so that the motor axis A is lower than the top of a wheel mounted on the wheel mounted on the wheel hub assembly3.

Referring now toFIG.5, this shows a side view of the wheel hub assembly3, which comprises a hub drive gear9, to which is secured a suspension arm end of a brake disc unit31by means of bolts34. A wheel end of the brake disc unit31is provided with a wheel mount which in this embodiment is an annular wheel mounting plate35from which extend a plurality of wheel mounting studs33. A wheel7may be secured to the wheel hub assembly3by means of the wheel mounting studs33, as is conventional in the art.

The hub drive gear9and brake disc unit31are mounted on an axle stub32which extends from the intermediate portion1cof the suspension arm1, and can rotate around the axle stub32. The longitudinal axis of the axle stub32extends along the wheel axis B, and the axle stub32may be integral with or secured to the intermediate portion1cof the suspension arm1, e.g. by welding. The hub drive gear9is connected to the motor/generator2by means of the driveline.

A conventional bearing assembly (not shown) may be provided to minimise wear and frictional energy losses as the hub drive gear9and brake disc unit31rotate around the axle stub32.

The brake disc unit31is provided with a brake disc36which is located between the suspension arm end and the wheel end of the unit31, and which extends radially outwardly of the wheel axis B.

As best shown inFIGS.1&3, in this embodiment, the suspension arm assembly also includes a brake cylinder5which is mounted on the bracket51which is attached to the suspension arm1. The brake cylinder5is mounted above the wheel hub assembly3, and is connected to a brake caliper54which is mounted on the suspension arm1with a linkage52. The brake cylinder5has a longitudinal axis and operates to produce a force parallel to this axis. The linkage52is pivoted at a pivot bracket53mounted on the suspension arm1. This way the force output from the remotely mounted brake cylinder is transmitted to the brake caliper54to cause the brake caliper54to clamp around the brake disc36and brake the wheel7as is conventional in the art. In this embodiment, the brake cylinder is arranged so that, in use, the brake cylinder axis is generally horizontal. It should be appreciated, however, that the brake cylinder5could equally be mounted on the suspension arm1with its axis oriented generally vertically.

In this embodiment, the brake cylinder5is mounted on the driveline portion1eof the suspension arm1.

Advantageously, the driveline is a mechanical driveline, and various embodiments of possible mechanical driveline configurations to transmit power between the motor/generator2and the wheel hub assembly3are illustrated inFIGS.6-9. In all cases, the driveline is mounted on the suspension arm1, and in this embodiment on the driveline support portion1eof the suspension arm1as described above.

In the embodiment illustrated inFIG.6, the motor/generator2is connected to the hub drive gear9of the wheel hub assembly3by a series of intermeshing gears91a,91bwhich are mounted on gear axle stubs which are arranged along the driveline support portion1eof the suspension arm1, the gears91a,91bbeing rotatable around their respective axle stub.

The rotor of the motor/generator2drives or is driven by a drive shaft97on which is mounted a motor drive gear92. The motor drive gear92meshes with a first intermediate gear91a, which in turn meshes with a second intermediate gear91b, which in turn meshes with the hub drive gear9. Thus, when the motor/generator2is operated as a motor, the rotation of the rotor rotates the motor drive gear92, the two intermediate gears91a,91b, the hub drive gear9, and hence the wheel7. Conversely, when operated as a generator, the wheel7rotates the hub drive gear9, the intermediate gears91a,91b, the motor drive gear92and the rotor of the motor/generator2.

Whilst in this embodiment, two intermediate gears91a,91bare provided it will be appreciated that there may be more or fewer than that.

In an alternative embodiment illustrated inFIG.7, a bevel gear arrangement is used. In this embodiment, the motor drive gear104and hub drive gear106are bevel gears. The rotor of the motor/generator2is connected to the motor drive bevel gear104which is driven by the hub drive bevel gear10through bevel pinions101,105and transmission shaft102as shown inFIG.7. The transmission shaft102is supported by shaft bearings103, which are mounted on the driveline portion1eof the suspension arm1.

In a further alternative embodiment illustrated inFIG.8, a belt drive arrangement is used. In this embodiment, the motor drive gear is replaced by a motor drive pulley112, and the hub drive gear by a hub drive pulley111. The rotor of the motor/generator2is connected to the motor drive pulley112which drives or is driven by hub drive pulley111through a belt113.

In a further alternative embodiment illustrated inFIG.9, a chain drive is used. In this embodiment, the motor drive gear is replaced by a motor drive sprocket122, and the hub drive gear by a hub drive sprocket. The rotor of the motor/generator2is connected to the motor drive sprocket122which drives or is driven by brake disc drive sprocket121through chain123.

In all the above embodiments, the whole driveline may be housed inside the cavity in the suspension arm1which is sealed and covered with a suspension driveline cover14.

It will be appreciated that the ratio of the torque generated by the motor/generator2and the torque applied to the wheel7can be tailored by the choice of size ratios of the various gears/drive pulleys or sprockets.

Ideally, the motor/generator2is selected which produces a relatively low torque when operated as a motor, and the size ratios of the gears/drive pulleys/sprockets are chosen so as to increase the torque applied to the wheel7. In other words, the size ratios of the gears/drive pulleys/sprockets are chosen so that the speed of rotation of the wheel7is significantly lower than the speed of rotation of the rotor of the motor/generator2.

An alternative embodiment of suspension arm assembly is illustrated inFIG.10. In this embodiment, the wheel hub assembly includes an epicyclic gear train140, so as to further increase the torque increase/speed reduction from the motor/generator2to the wheel7. The epicyclic gear train140is connected between the wheel and the driveline to transmit a drive torque between the driveline and the wheel. By virtue of this arrangement, a relatively high speed/low torque motor/generator2can be used, and sufficient torque produced at the wheel7to drive even a heavy goods vehicle.

Epicyclic gear trains (or planetary gear trains) comprise at least two gears mounted so that the two gears mesh and the centre of one gear revolves around the centre of the other. A carrier connects the centres of the two gears and rotates to carry one gear (designated the planet gear) around the other gear (named the sun gear). More than one planet gear can be provided. They also comprise an outer gear ring, which has radially inward facing teeth which mesh with the teeth of the planet gear or gears. The outer gear ring may be fixed and the sun gear driven, so that rotation of the sun gear causes the carrier to rotate. Alternatively, the carrier may be fixed and the sun gear driven to rotate the ring gear.

In the embodiment illustrated inFIG.10, the wheel hub assembly is provided with an epicyclic gear train140in which the outer ring gear141is fixed, and the carrier144is rotated as the sun gear142is driven. In this embodiment, the sun gear142is connected to the mechanical driveline so that the mechanical driveline drives or is driven by rotation of the sun gear, and the carrier144is connected to the wheel mounting plate35by carrier mounting bolts147such that rotation of a wheel mounted on the wheel mounting plate35is driven by or drives rotation of the carrier144.

In this embodiment, the driveline is similar to that illustrated inFIG.6in that the motor/generator2is connected to the hub drive gear9of the wheel hub assembly3by a series of intermeshing gears91a,91bwhich are arranged along the driveline support portion1eof the suspension arm1. The rotor of the motor/generator2drives or is driven by a motor drive shaft97on which is mounted a motor drive gear92. The motor drive gear92meshes with a first intermediate gear91a, which in turn meshes with a second intermediate gear91b.

In this embodiment, however, the second intermediate gear91bmeshes with a compound gear assembly which comprises a compound hub gear95, a hub gear shaft96and a hub pinion94. The compound hub gear95is mounted on one end of the hub gear shaft96, and the hub pinion94on the other end of the hub gear shaft96. The hub gear shaft96extends through an aperture provided in the driveline support portion1eof the suspension arm, and is supported by a bearing assembly136which allows the hub gear shaft96to rotate relative to the suspension arm1. The compound hub gear95is arranged on the same side of the suspension arm1as the intermediate gears91a,91band meshes with the second intermediate gear91b. The hub pinion94is located on the other side of the suspension arm1and meshes with the hub drive gear9.

In this embodiment, rather than being mounted on an axle stub which is secured to the suspension arm1, the hub drive gear9is mounted on one end of a wheel hub drive shaft150which extends along the interior of a tubular axle stub32so that the wheel hub drive shaft150can rotate within the axle stub32about the wheel axis B. The axle stub32is mounted on the intermediate portion1cof the suspension arm1via a hub drive gear housing98.

The sun gear142of the epicyclic gear train140is mounted on the opposite end of the wheel hub drive shaft150, and therefore rotation of the sun gear142is driven by rotation of the hub drive gear9. The sun gear142meshes with the planet gears143(in this embodiment there are five planet gears143) which are mounted on planet gear carrier144. The planet gears143mesh with outer ring gear141, which is secured to the axle stub32to prevent rotation of the ring gear141.

The planet gear carrier144is secured to the brake disc unit31via the wheel studs33and carrier mounting bolts147, and the brake disc unit31is mounted around the axle stub32via a conventional bearing assembly137which is provided to minimise wear and frictional energy losses as the brake disc unit31rotates around the axle stub32. It will be appreciated rotation of the sun gear143will drive or by driven by rotation of the planet gear carrier144, which in turn will transfer rotation to or from the wheel7about the axle stub32via the wheel studs33.

In a further alternative embodiment, illustrated inFIGS.11,12and13, the wheel hub assembly3is provided with two epicyclic gear trains—a first epicyclic gear assembly130, and a second epicyclic gear assembly140. This may increase the torque applied to the wheel7even further, and may allow a particular high speed/low torque motor/generator2to be used to drive a heavy goods vehicle.

In this embodiment, there is no compound gear assembly. Instead, there are three intermediate gears91a,91b,91c, and the third intermediate gear91cmeshes with the wheel hub drive gear9. The wheel hub drive gear9is mounted on a hub gear shaft96which extends through an aperture provided in the intermediate portion1cof the suspension arm1. The hub gear shaft96is supported by a bearing assembly136which allows the hub gear shaft96to rotate relative to the suspension arm1. The wheel hub drive gear9is mounted on one end of the hub gear shaft96and the sun gear132of the first epicyclic gear assembly130is mounted on the other end of the hub gear shaft96. Rotation of the sun gear132of the first epicyclic gear assembly130is therefore driven by rotation of the wheel hub drive gear9.

The sun gear132meshes with the planet gears133(in this embodiment there are five planet gears133) which are mounted on carrier134. The planet gears133mesh with outer ring gear131, which is secured to a hub drive gear housing98which is mounted on the intermediate portion1cof the suspension arm1, to prevent rotation of the ring gear131.

The carrier134is secured to one end of a wheel hub drive shaft150which again extends along the interior of the tubular axle stub32, so that rotation of the carrier134drives rotation of the wheel hub drive shaft150within the axle stub32about the wheel axis B. The axle stub32is mounted on the intermediate portion1cof the suspension arm1via the hub drive gear housing98.

The second epicyclic gear train140is configured in exactly the same way as the epicyclic gear train140described above in relation toFIG.10, with the sun gear142of the second epicyclic gear train140being mounted on the other end of the wheel hub drive shaft150, rotation of the wheel hub drive shaft150thus driving the rotation of the sun gear142, the planet gear carrier144and wheel mount35as described above.

Typically, a vehicle is provided with one or more pairs of ground engaging wheels which are located on opposite sides of the vehicle. Examples of such vehicles8are illustrated inFIGS.14-18. The vehicle8may, for example, be a commercial vehicle8and have a vehicle body81includes a chassis81aon which is mounted a structure81bwhich forms a compartment into which goods may be placed for transport. The suspension arm1and spring4are advantageously secured to the vehicle chassis81a.

The suspension arm1is intended to be used as a trailing arm suspension, so the first portion1aof the suspension arm1is pivotally connected to the vehicle chassis81aat a point which is further towards the front of the vehicle than the wheel axle B.

In the embodiment illustrated inFIGS.14-18, the vehicle8is a semi-trailer of an articulated heavy goods vehicle or a rigid vehicle.FIGS.14A &14Bshow a rigid body vehicle with one pair of wheels which are connected to the vehicle body81by means of a suspension arm1as described above.

The vehicle8may have more than one pair of wheels, andFIG.15shows a rigid body vehicle8with two adjacent pairs of wheels7, whilstFIG.16shows a semi-trailer with three adjacent pairs of wheels. The vehicle8could equally be a trailer, with pairs of wheels located towards its front and rear. Where the vehicle is a semi-trailer8it include an apparatus (such as a kingpin83) by means of which the trailer may be connected to a tractor so that the tractor can tow the trailer, as illustrated inFIG.16, and as is well known in the art.

Where the vehicle is provided with plurality of pairs of wheels7in tandem, as illustrated inFIGS.15&16, each wheel7of each pair may be mounted on a suspension arm1as described above, so that each wheel7can be driven by an independent motor2. This need not be the case, however, and some of the wheels may not be driven wheels.

Each wheel7of the pair of wheels7is mounted on the vehicle body using a suspension arm1as described above, by securing a wheel to the wheel hub assembly3so that the wheel rotates with the wheel hub assembly3about the wheel axis B. The suspension arms1can be unconnected and therefore used independently on each wheel7of the pair, or the two suspension arms1could be connected with an axle beam13as shown inFIGS.19A and19B. In this embodiment, the axle beam13is secured to the first portion1aof the suspension arm1, at a position adjacent to the bushing11by means of which the suspension arm is pivotally connected to the vehicle chassis. Each end of the axle beam13is therefore lower than the wheel axis B.

The arrangement of the suspension arm1and associated parts relative to the vehicle8is illustrated in more detail inFIGS.20A and20B, and these show how the suspension arm1can pivot relative to the vehicle body81about the pivot axis C to facilitate generally vertical movement of the wheel7relative to the vehicle body81.FIG.20Ashows the position of the suspension arm1when the spring4is extended and the wheel7in a lowered position relative to the vehicle body81, whilstFIG.20Bshows the position of the suspension arm1when the spring4is compressed and the wheel7is in a raised position relative to the vehicle body81.

Instead of being connected directly to the vehicle body81by means of a bushing11as described above, the first portion1aof the suspension arm1may be pivotally connected to the vehicle body81via a torque rod. In the case, the torque rod has a first end which is pivotally connected to the first portion1aof the suspension arm1and a second end which is pivotally connected to the vehicle body81. This arrangement may be applied to any of the configurations of suspension arm1described above.

Where two opposite suspension arms1are connected by means of an axle beam13as described above, the torque rods may be connected to the axle beam13as illustrated inFIGS.21and22. In this embodiment, the axle beam13joins the first portions1aof the two suspension arms1, and is connected to the vehicle body81by means of two lower torque rods16.

In this embodiment, the lower torque rods16are arranged in a V configuration, with their first ends being pivotally connected to a central portion of the axle beam13and their second ends being connected the vehicle body81at or adjacent to the two opposite sides of the vehicle body81. In this embodiment, the first ends of the torque rods16are secured to a plate17which is mounted on the axle beam13, and which lies in a generally horizontal plane when the suspension arm1is mounted on the vehicle.

The damper6could be mounted in the same position as in the embodiments illustrated inFIGS.1-20, but in the embodiments illustrated inFIGS.21and22, it is mounted on the second portion1bof the suspension arm1adjacent to the spring4.

In this embodiment, each suspension arm1is provided with an upper torque rod15, a first end of which is pivotally connected to the suspension arm1and a second end of which is pivotally connected to the vehicle body81at a point which is higher off the ground than the connection with the lower torque rod16. In this embodiment, the upper torque rods15are each pivotally connected to the support strut1fof the suspension arm1.

The pivotal connections between the torque rods15,16and the suspension arm1and vehicle body81are configured such that the torque rod15,16can pivot in a generally vertical plane. In this embodiment each of these pivotal connections is provided by means of a pin201which extends generally horizontally through a bush at the respect end of the torque rod15,16. It should be appreciated, however, that the torque rod pin could be vertical, with vertical movement of the suspension arm1accommodated by deformation of a rubber bushing between the pin and the torque rod.

The arrangement of this embodiment of suspension arm1and associated parts relative to the vehicle8is illustrated in more detail inFIGS.23A and23B, and these show how the suspension arm1can move relative to the vehicle body81to facilitate generally vertical movement of the wheel7relative to the vehicle body81.

The torque rods15,16are arranged such that when they are connected to the vehicle body81such that they extend generally horizontally when the spring4is extended, as illustrated inFIG.23A. When the spring4is compressed, they remain generally parallel to one another, but inclined so that their first end is higher than their second end, as illustrated inFIG.23B.

It will be appreciated that when the suspension arm1is pivotally connected to the vehicle body81directly as described in relation toFIGS.1-20above, the wheel hub assembly3moves along an arc of a circle, so is displaced horizontally (albeit by a relatively small amount) as well as vertically. In contrast, by virtue of the use of torque rods15,16the horizontal displacement of the wheel hub unit3can be reduced or eliminated.

The embodiment illustrated inFIGS.21to23Bis a non reactive suspension system in which breaking and acceleration loads cause pivoting of the upper and lower torque rods15,16relative to the vehicle body81, rather than vertical movement of the body81. The lower torque rods are arranged in V shape to prevent lateral displacement of the suspension arm1as a result of lateral forces along wheel axis B caused by cornering or hitting the curb.

Although not essential, in this embodiment the suspension arms1are provided with an anti-roll bar18which is secured to the axle beam13via two anti roll bar bearings20which allows the anti-roll bar18to rotate about its longitudinal axis. The anti-roll bar18extends generally parallel to the axle beam13, and each end is pivotally connected to vehicle body81by means of a drop link19.

The anti-roll bar18is of a conventional configuration and is designed to provide the axle beam with the desired roll stiffness for any given application. The drop links19allow the ends of the anti roll bar to move horizontally as the axle beam13moves vertically, whilst the anti-roll bar18prevents the axle beam from rotating relative to the longitudinal axis of the vehicle.

By arranging suspension arm1as described above, the motor/generator2does not occupy the space between the wheels7in the pair. The motor/generator2occupies space above the wheel7, and therefore can be accommodated in a wheel arch portion of the vehicle body81. This means that a floor82of the structure81bcan be lowered to be very close to the ground, in front of and behind the pair of wheels7(as illustrated inFIGS.14A,14B,15&16), and also between the wheels7(as illustrated inFIGS.17&18), there being only a relatively small area over the wheels7in which the floor82is raised to form the wheel arches82a.

By lowering the floor82of the structure81b, and minimising the space occupied the wheel arches across the width of the vehicle, it may be possible to accommodate two layers of pallets86within the structure, without increasing the overall height of the vehicle, as illustrated inFIG.18. In this embodiment, there is a generally horizontal deck87which divides the interior of the structure into an upper volume and a lower volume, a layer of pallets86two pallets wide is arranged on the floor82of the structure81bin the lower volume, and a layer of pallets86three pallets wide is arranged on the deck87in the upper volume.

Where an axle beam13is provided, the axle beam13is advantageously offset both vertically and horizontally relative to the wheel axis B to allow the axle beam13to move under the extremely low floor82as shown inFIGS.17&18.

The inventions are is not limited by the embodiments described above, and are as set out in the appended claims.