GB2575011A

GB2575011A - Suspension system

Info

Publication number: GB2575011A
Application number: GB201807989A
Authority: GB
Inventors: Edward Byers Sealy Mark; Wright Christopher
Original assignee: Tata Motors European Technical Centre PLC; Tata Motors Ltd
Current assignee: Tata Motors European Technical Centre PLC; Tata Motors Ltd
Priority date: 2018-03-15
Filing date: 2018-05-17
Publication date: 2020-01-01
Anticipated expiration: 2038-05-17
Also published as: GB201807989D0; GB2575011B

Abstract

Embodiments of the present invention provide a suspension system 200 for a vehicle (500 in Figure 4). The suspension system 200 comprises a wheel hub knuckle 206, a suspension strut 202, a lower control arm 204 and a steering assembly 226. The wheel hub knuckle 206 is rotatably coupled to the strut 202 utilising a first coupling 207 that provides a single degree of rotational freedom of the wheel hub knuckle 206 relative to the strut 202 at a first location; and is coupled to the lower control arm 204 utilising a second coupling comprising a ball type joint 218 at a second location. The wheel hub knuckle 206 is coupled to the steering assembly 226 at a third location. The steering assembly 226 is operable to rotate the wheel hub knuckle 206 about a steering axis 222 passing through the first location and the second location. Advantageously, the suspension system 200 allows the steering axis 222 to be positioned independently of the connection between the suspension strut 202 and the vehicle body.

Description

SUSPENSION SYSTEM

TECHNICAL FIELD

The present invention relates to a suspension system, particularly, but not exclusively, to a suspension system for steerable wheels of a vehicle, for example front wheels of a vehicle. Aspects of the invention relate to a suspension system, to a wheel hub knuckle, to a method of making a wheel hub knuckle, and to a vehicle.

BACKGROUND

Suspension systems are provided in vehicles to reduce noise, vibration and harshness by isolating the passengers from road shocks. Suspension systems also regulate the stability of the vehicle by enabling contact between the wheels and the road to maintain proper wheel geometry. Suspension systems coupled to steerable wheels need to accommodate pivoting of the wheels to steer in addition to allowing the wheels to move relative to the vehicle in response to road shocks.

There are two main categories of suspension systems; dependent and independent. Dependent, or ‘rigid axle’ systems have the two front or back wheels connected on the same axle. This system is mechanically straightforward, and therefore generally robust. However, as the wheels react to road shocks in conjunction, the efficacy of the handling is reduced, particularly when compared to independent suspension systems. Independent systems, as the name suggests, are configured so that the individual wheels can move independently from one another, reacting individually to road disturbances. Consequently, the configuration of independent suspension systems can be rather complex, but does allow for better vehicle handling, and can enhance the stability of the vehicle.

As independent suspension systems afford characteristics that are advantageous for modern on-road cars, it is these that are typically used. By using an independent system, the individual wheel geometries can be controlled. The positioning of the wheel includes the steered direction, and the camber, caster and toe angle alignments.

The MacPherson type is a common front suspension system which comprises a strut having a telescopic damper and coil pivoted at the top end to the vehicle body, which is employed as the upper steering pivot. The strut is typically rigidly connected to a steering knuckle, and a lower steering pivot is typically provided at a pivotable connection between the steering knuckle and a lower control arm. Consequently, the MacPherson type is both a light and compact suspension system, which is particularly useful for front suspensions where packaging volume is an issue.

Another known suspension system that has been employed on high-performance frontwheel drive vehicles comprises a suspension strut having a telescopic damper and coaxial spring that is rigidly connected at its lower end to a bracket that defines three mounting points for ball joints. A first and a second of the mounting points are arranged to be connected to a wheel hub knuckle, such that a steering axis passing through the first and second mounting points is defined. A third mounting point on the bracket is connectable to a lower control arm. In this way, the functions of steering and absorbing road shocks are effectively separated, as steering inputs cause rotation of the wheel hub knuckle about the axis passing through the first and second mounting points, and road shocks cause vertical movement of the bracket and connected wheel hub knuckle and rotation of the wheel-hub knuckle and connected bracket about an axis passing through the third mounting point. However, the introduction of an additional bracket and an additional joint increase the cost and weight of the system, relative to the conventional MacPherson system described above. Furthermore, provision of a bracket that defines first, second and third mounting points may cause difficulty in packaging the system in the available space, as it is necessary for the bracket to be positioned such that it does not interfere with the constant velocity joint that connects the drive shaft to the wheel.

Modern vehicle manufacturers will often produce several different vehicle lines based on a common platform, which is a set of components that are shared between different vehicles. Such a platform typically defines several features of the vehicles that are to be built using the platform, including the type of suspension. If a conventional MacPherson-type suspension system is to be used then the upper steering pivot is generally defined by the platform, but the position of the lower steering pivot may move depending on various factors including the geometry of the wheels that are fitted to a particular vehicle. Accordingly, the orientation of the steering axis (which passes through the upper and lower steering pivots) may be sub-optimal for some of the vehicles made using a platform, or it may be impossible to obtain an acceptable steering axis with some types of wheel. A sub-optimal orientation of the steering axis may degrade the steering feel or the self-centring behaviour of the steering system.

It is an object of certain embodiments of the invention to at least mitigate one or more of the problems of the prior art.

SUMMARY OF THE INVENTION

Aspects of the invention relate to a suspension system, to a wheel hub knuckle, to a method of making a wheel hub knuckle, and to a vehicle as claimed in the appended claims.

According to an aspect of the invention for which protection is sought there is provided a suspension system for a vehicle comprising:

a wheel hub knuckle, a suspension strut, a lower control arm and a steering assembly; the wheel hub knuckle rotatably coupled to the strut utilising a first coupling at a first location and coupled to the lower control arm utilising a second coupling comprising a ball-type joint at a second location, the wheel hub knuckle being coupled to the steering assembly at a third location, wherein the first coupling provides a single degree of rotational freedom of the wheel hub knuckle relative to the strut, and the steering assembly is operable to rotate the wheel hub knuckle about a steering axis passing through the first location and the second location. Advantageously, such a suspension system allows the steering axis to be positioned independently of the connection between the suspension strut and the vehicle body. This improves flexibility, as it allows both of the locations that define the steering axis to be positioned independently for each vehicle that is produced using a given platform.

Although it is a common term to a person skilled in the art, herein a knuckle should be understood to be a rigid component which is coupled to, and structurally supports, at least one other vehicle component. For example, a typical wheel hub knuckle, which may also be referred to as a steering knuckle or a spindle, is a rigid component which carries a wheel hub and is coupled to suspension control arms.

As used herein, the term “suspension strut” is to be taken to mean a strut that forms part of a suspension system and that is operable to absorb road shocks, at least so some extent. Accordingly, the term “suspension strut” is not limited to rigid, inextensible struts. In some embodiments, the suspension strut may comprise a MacPherson-type strut. Within the present specification, the term “MacPherson-type strut” is to be understood to mean a strut that is pivotably connected to the vehicle body at an upper end thereof and that has an integral telescopic damper and a coil spring disposed around the strut.

In an embodiment, the first coupling comprises a spindle-type coupling (alternatively referred to herein as a spindle-type joint). In an alternative embodiment, the first coupling comprises two ball-type joints.

In an embodiment, the suspension system comprises an anti-roll bar coupled to the strut, wherein the anti-roll bar is arranged to limit axial rotation of the strut relative to the vehicle body. Advantageously, this helps to prevent the steering system from rotating about an axis passing through the second location and the location at which the strut is connected to the vehicle body.

Optionally, the strut comprises an integral damper. Such a damper may allow the suspension strut to absorb energy from road shocks. The strut may further comprise a spring, which may be disposed around the strut. The spring may be connected at an end thereof to the vehicle body. Alternatively, an end of the spring may abut the vehicle body. Positioning of the spring on the strut may provide good packaging efficiency. The strut may be a MacPherson-type strut.

In an embodiment, the lower control arm is rotatably couplable to the vehicle body at a fourth location remote from the second location.

In an embodiment, the system further comprises a wheel hub coupled to the wheel hub knuckle.

Optionally, the steering axis is near vertical. The steering axis may have a caster angle of less than 20 degrees. Optionally the caster angle may be between 3 and 12 degrees. Further optionally, the caster angle may be approximately 7 degrees. The steering axis may have a kingpin angle of less than 20 degrees. Optionally, the kingpin angle may be between 1 and 10 degrees. Further optionally, the kingpin angle may be approximately 5 degrees.

According to another aspect of the invention for which protection is sought there is provided a wheel hub knuckle comprising a first mounting point connectable to a suspension strut and a second mounting point connectable to a lower control arm, wherein the first mounting point defines a part of a spindle-type joint and the second mounting point defines a part of a ball joint, wherein the spindle-type joint is operable to provide a single degree of rotational freedom of the wheel hub knuckle relative to the strut, the single degree of rotational freedom comprising rotation about an axis passing through a centre of rotation of the ball joint. Such a wheel hub knuckle may form part of a suspension system as described above.

In an embodiment, the wheel hub knuckle further comprises a third mounting point, the third mounting point being connectable to a steering assembly.

According to another aspect of the invention for which protection is sought there is provided a method of making a wheel hub knuckle as described above, wherein the first mounting point and the second mounting point are produced by a single machining operation. Advantageously, machining the first and second mounting points in a single operation ensures that a centre of rotation of a ball joint connected to the second mounting point is located on an axis of rotation of a spindle-type joint connected to the first mounting point. This allows a steering axis to be defined between the spindle-type joint and the ball joint, and prevents excessive wear from occurring as a result of misalignment of the spindle-type joint and the ball joint.

According to another aspect of the invention for which protection is sought there is provided a vehicle comprising a suspension system or a wheel hub knuckle as described above. The vehicle may have at least one wheel that is both steerable and driven. The vehicle may be a front-wheel drive vehicle or an all-wheel drive vehicle, for example a four-wheel drive 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

Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which:

Figure 1 shows a cross section through a conventional suspension system using a MacPherson strut (Prior Art);

Figure 2 shows a suspension system having a modified inner knuckle in an embodiment of the present invention;

Figure 3 shows another view of the suspension system shown in figure 2; and

Figure 4 shows a vehicle in an embodiment of the present invention.

DETAILED DESCRIPTION

Figure 1 shows a cross section through a suspension assembly 100 for a steerable wheel of a vehicle. The suspension assembly comprises a MacPherson-type strut 102, a wheel hub knuckle 106 and a lower control arm 104. The MacPherson-type strut 102 comprises a telescopic damper 108 having a coil spring 110 therearound, thereby allowing the strut 102 to absorb energy from road shocks. The strut 102 is rigidly coupled to the wheel hub knuckle 106 and connected to a location on the vehicle body via a ball joint 112.

The wheel hub knuckle 106 is connected to a wheel hub 114 that is rotatably coupled to a wheel 116, thereby allowing the wheel 116 to rotate relative to the suspension assembly and the vehicle body. The wheel 116 may be a driven wheel, and as such may be provided with torque via a drive shaft 124. The wheel hub knuckle 106 is also connected to the lower control arm 104 via a ball joint 118. The lower control arm 104 is connected to the vehicle body via spindle-type joint 120 that allows the lower control arm to rotate relative to the vehicle body about an axis that is substantially parallel with the direction of travel of the vehicle (i.e. out of the page as shown in figure 1).

The wheel hub knuckle 106 is also coupled to a steering assembly (not shown), that is operable to rotate the wheel hub knuckle 106 and the associated wheel 116 so as to steer the vehicle. When the steering assembly is actuated to steer the vehicle the wheel hub knuckle 106 and the MacPherson-type strut 112 rotate together about axis 122, which passes through the ball joint 118 connecting the wheel hub knuckle to the lower control arm and the ball joint 112 connecting the MacPherson-type strut to the vehicle body.

An anti-roll bar (not shown) may be provided to limit relative movement of the wheel 116 relative to the other wheel on the same axis.

The suspension assembly shown in figure 1 is simple in its construction and is suitable for wheels that are both steered and driven (e.g. the front wheels of conventional front-wheel drive vehicles). Accordingly, suspension systems similar to that shown in figure 1 are widely used.

The present inventors have recognised that when conventional suspension systems such as that shown in figure 1 are implemented on vehicle platforms that are common to several different vehicle lines the orientation of the steering axis 122 may be sub-optimal for some of the vehicle lines. This is because the position of the ball joint 112 that connects the MacPherson-type strut 102 to the vehicle body is generally fixed by the platform geometry, but the position of the ball joint 118 that connects the lower control arm 104 to the wheel hub knuckle may vary between vehicle lines, depending on various features of the particular vehicle line. In particular, the geometry of the wheels fitted to a particular vehicle may significantly affect the positioning of the ball joint 118. This may make it impossible to provide an acceptable steering axis for certain combinations of platform and wheel geometry.

Figures 2 and 3 show a suspension system 200 according to an embodiment of the present invention. Suspension system 200 comprises a suspension strut 202 having a coil spring 210 disposed therearound and an integral telescopic damper 208 disposed coaxially with the coil spring 210. An upper end of the suspension strut (not shown) is connected to the vehicle body via a ball joint. It will be understood that the suspension strut 202 may be referred to as a MacPherson-type strut.

The lower end of suspension strut 202 is connected to a wheel hub knuckle 206 via a spindle-type joint 207. It will be understood that the spindle-type joint 207 provides only a single degree of freedom between the strut 202 and the wheel hub knuckle 206. The single degree of freedom comprises rotation about axis 222. The suspension strut 202 is also coupled at a lower end thereof to an anti-roll bar 228.

The wheel hub knuckle 206 carries a wheel hub 214 that is operable to be rotatably coupled to a road-engaging wheel of the vehicle. The wheel hub knuckle 206 is also connected to a lower control arm 204 via a ball joint 218. The lower control arm 204 is also connected to the vehicle body by a spindle-type joint 220 at an end remote from the ball joint 218. The spindle-type joint 220 connecting the lower control arm 204 to the vehicle body is operable to allow rotation about an axis substantially parallel to the forward direction of travel of the vehicle (i.e. approximately out of the page as shown in figure 2). In some embodiments the lower control arm 204 may be connected to the vehicle body by two or more spindle-type joints having coaxial axes of rotation.

The wheel hub knuckle 206 is also coupled to a steering rod 226 via ball-type joint 227. A drive shaft 224 is operable to deliver torque from a prime mover such as an engine or an electric machine (not shown) to a wheel carried on the wheel hub 214. It will be understood that the drive shaft 224 is connected to the wheel hub 214 by a conventional constant velocity joint, which is contained within boot 230. Such a joint allows a connection between the drive shaft 224 and the wheel carried on the hub 214 to be maintained during changes in orientation of the wheel as a result of steering inputs and/or road shocks.

In use, the suspension system 200 is operable to absorb road shocks and to allow the wheel connected to the wheel hub 214 to be steered, thereby effecting steering of the vehicle.

It will be understood that it is important that the spindle-type joint 207 provides only a single degree of freedom, as otherwise it would be possible for the wheel hub knuckle 206 to rotate to a significant degree about either or both of a longitudinal or transverse axis passing through ball joint 218, without the strut 202 rotating in a similar manner. This would cause an undesirable change in the orientation of the wheel connected to the wheel hub 214, potentially causing an unacceptably large articulation of the constant velocity joint contained in boot 230 and uncontrollable steering of the vehicle. Provision of a spindle-type joint that is able to resist rotation of the wheel hub knuckle 206 relative to the strut 202 about all axes other than the steering axis 222 prevents such undesirable behaviour during road shocks. Accordingly, the spindle-type joint 207 obviates the need for a bracket connecting the strut 202 to the wheel hub knuckle 206 at a lower end of the wheel hub knuckle 206. This reduces the cost and weight of the suspension system 200, and improves the packaging requirements of the system, because it is not necessary to provide a bracket that must pass around the drive shaft 224 and the constant velocity joint housed in boot 230.

Because the spindle-type joint 207 only allows rotation of the wheel hub knuckle 206 relative to the strut 202 about a single axis, it is important that the centre of the ball joint 218 is precisely located on the axis 222 about which the spindle-type joint 207 is operable to rotate. Placement of the centre of the ball joint 218 away from the axis 222 may cause rapid wear of the ball joint 218 and/or the spindle-type joint 207, or may prevent steering of the wheel hub knuckle 206 if the misalignment between the axis along which the spindle-type joint 207 is operable to rotate and the centre of the ball joint 218 is severe. Alignment of the centre of the ball joint 218 and the axis of the spindle-type joint 207 may be achieved by various means. In the present embodiment, the features on the wheel hub knuckle 206 that defined the positions of the spindle-type joint 207 and the ball joint 218 are created in a single machining operation, thereby ensuring that no misalignment is introduced during manufacture of the wheel hub knuckle 206. Alternatively, the features on the wheel hub knuckle 206 that define the positions of the spindle-type joint 207 and the ball joint 218 may be created in multiple machining operations, for example using computer numerical control (CNC) machinery programmed to ensure coaxial alignment of the features that define the positions of the spindle-type joint 207 and the ball joint 218.

Although the embodiment shown in figures 2 and 3 illustrates a spindle-type joint 207 connecting the strut 202 to the wheel hub knuckle 206, it will be understood that in other embodiments a different type of joint that provides only a single degree of rotational freedom of the strut 202 relative to the wheel hub knuckle 206 could be provided. For example, two or more ball joints positioned on axis 222 and each connecting the wheel hub knuckle 206 to the strut 202 could replace the spindle-type joint 207.

When a wheel connected to the wheel hub 214 encounters a road shock the wheel hub knuckle 206 is operable to move vertically relative to the vehicle body by compressing the telescopic damper 208 of the suspension strut 202 and causing the lower control arm 204 to rotate about the spindle-type joint 220. It will be understood that the stiffness of the coil spring 210 and the damping rate of the telescopic damper 208 can be varied to vary the “feel” of the suspension on different vehicle lines.

Steering of the wheel connected to the wheel hub 214 can be effected by movement of the steering rod 226, which is connected to a steering rack (not shown) that is controllable by a driver of the vehicle or an autonomous vehicle system via a steering wheel or other input means (not shown). Movement of the steering rod 226 causes the wheel hub knuckle 206 and the connected wheel hub 214 to rotate about steering axis 222, which passes through the spindle-type joint 207 which connects the wheel hub knuckle 206 to the suspension strut 202 and the ball joint 218 which connects the wheel hub knuckle 206 to the lower control arm 204.

As can be seen in figure 2 and figure 3, the anti-roll bar 228 is connected to the suspension strut 202 and acts to prevent the wheel hub knuckle 206 and the suspension strut 202 from rotating as a rigid body about an axis passing through the ball joint 218 connecting the lower control arm 204 to the wheel hub knuckle 206 and the ball joint connecting the upper end of the suspension strut 202 to the vehicle body (not shown).

The anti-roll bar 228 is connected to the lower end of the suspension strut 202 by a ball-type joint 232. The ball-type joint 232 may be provided with a compliant cylindrical bushing, for example a cylindrical rubber bushing, that resists rotation of the anti-roll bar 228 relative to the strut 202 about all axes apart from a longitudinal axis of the bushing. The ball-type joint 232 causes the end of the anti-roll bar 228 to move vertically with the end of the strut 202. Rotation of the wheel hub knuckle 206 and the suspension strut 202 as a rigid body (about an axis passing through ball joint 218 and the top of the strut 202) is substantially prevented, because the ball joint 232 is not aligned with the axis passing through the ball joint 218 and the upper end of the strut 202. Although bending of the anti-roll bar would allow some rotation of the wheel hub knuckle 206 and the suspension strut 202 as a rigid body, it will be understood that when a force is applied to the wheel hub knuckle 206 by the steering rod 226, the resistance to rotation about axis 222 is significantly lower than the resistance to rotation about the axis defined between the upper end of the suspension strut 202 and the ball joint 218. Accordingly, substantially all of the rotation caused by a steering force applied by the steering rod 226 causes rotation of the wheel hub knuckle 206 about axis 222.

In addition to its function of limiting steer about the axis between the upper end of the strut and the ball joint 218, the anti-roll bar 228 also limits vertical movement of the lower end of the strut 202, and therefore the associated wheel. The anti-roll bar 228 has a conventional ‘U-shaped’ profile with the opposite end to the one shown in figure 2 connected in a similar way to a lower end of a suspension strut connected to a wheel on the opposite side of the vehicle. In this way, vertical movement of a wheel on one side of the vehicle relative to a wheel on the other side causes torsion of the cross piece connecting 228C that connects the arms 228A of the anti-roll bar 228. Accordingly, the torsional stiffness of the cross piece 228C determines the resistance to relative vertical movement of the wheels on opposite sides of the vehicle. As will be well understood by those skilled in the art, limiting relative movement of wheels on opposite sides of a vehicle via an anti-roll bar may reduce the tendency of the vehicle to roll as it travels round corners.

A particular advantage of the steering system shown in figures 2 and 3 is that both of the joints 207, 218 that define the steering axis 222 are provided on the wheel hub knuckle 206. Accordingly, a vehicle line that is produced using a given platform may be provided with a steering axis that is substantially independent of the platform geometry by designing a new wheel hub knuckle 206 according to the present invention. Embodiments of the present invention therefore allow vehicles produced on a common platform to be provided with tailored steering axes, without the need to substantially redesign platform components.

A further advantage of embodiments of the present invention is that, because it is not necessary for the steering axis to pass through the joint connecting the upper end of the strut 202 to the vehicle body, it is possible to provide a steering axis having lower kingpin and caster angles than would typically be the case for prior art vehicles employing MacPherson-type struts to provide suspension on steered wheels. Although it will be understood that the present invention provides a large degree of design freedom in selecting the precise geometry of the wheel hub knuckle 206 to provide an appropriate steering axis, the present inventors have recognised that it may be advantageous to provide a steering axis having a kingpin and caster angle that are close to zero degrees; that is a steering axis that is near vertical. In some embodiments, the steering axis may have a caster angle that is less than 20 degrees and a kingpin angle that is less than 20 degrees. In the embodiment illustrated in figures 2 and 3 the kingpin angle is approximately 5 degrees and the caster angle is approximately 7 degrees. Provision of such low caster and kingpin angles may provide an improved turning circle or increase the size of tyre that can be packaged in a given space. This is because low caster and kingpin angles reduce the tendency of the wheel to lean as it is steered, thereby allowing a wheel of a given size to be steered through a larger angle before the lean becomes unacceptable or causes a collision between part of the wheel and a component located in the wheel arch.

The advantages of certain embodiments of the present invention are achieved without a significant increase in weight or cost, as compared to a conventional MacPherson-type suspension system. This is because it is only necessary to introduce one additional articulating joint, and the anti-roll bar (an existing component of a MacPherson-type suspension system) is modified to ensure that steering inputs from the steering rod 226 do not cause significant rotation about an axis passing through the ball joint connecting the upper end of the strut 202 to the vehicle body and the ball joint 218 connecting the wheel hub knuckle 206 to the lower control arm 204.

It will be understood that suspension systems according to certain embodiments of the present invention may be employed to allow the wheels 502, 504 of a vehicle 500 to move vertically relative to the body of the vehicle 500, as shown in figure 4. In particular, the suspension systems of the present invention may be advantageously applied to wheels that are steered (for example wheels 502, as shown in figure 4). Suspension systems according to embodiments of the present invention may be usefully applied at wheels 502 that are both steerable and drivable, for example the front wheels on a conventional front-wheel drive or four-wheel drive vehicle 500. If a suspension system according to an embodiment of the present invention is employed at a wheel that is steerable and drivable then it is relatively straightforward to provide the packaging space around the suspension system required to connect a constant velocity (CV) joint to the wheel 502 to allow it to be driven by a prime mover of the vehicle 500, which may be an engine, an electric machine, or a combination thereof.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

1. A suspension system for a vehicle comprising:

a wheel hub knuckle, a suspension strut, a lower control arm and a steering assembly; the wheel hub knuckle rotatably coupled to the strut utilising a first coupling at a first location and coupled to the lower control arm utilising a second coupling comprising a ball-type joint at a second location, the wheel hub knuckle being coupled to the steering assembly at a third location, wherein the first coupling provides a single degree of rotational freedom of the wheel hub knuckle relative to the strut, and the steering assembly is operable to rotate the wheel hub knuckle about a steering axis passing through the first location and the second location.

2. A suspension system as claimed in claim 1, wherein the first coupling comprises a spindle-type coupling.

3. A suspension system as claimed in claim 1, wherein the first coupling comprises two ball-type joints.

4. A suspension system as claimed in any preceding claim, and further comprising an anti-roll bar coupled to the strut, wherein the anti-roll bar is arranged to limit axial rotation of the strut relative to the vehicle body.

5. A suspension system as claimed in any preceding claim, wherein the strut comprises an integral damper.

6. A suspension system as claimed in claim 5, wherein the strut further comprises a spring.

7. A suspension system as claimed in any preceding claim, wherein the lower control arm is rotatably couplable to the vehicle body at a fourth location remote from the second location.

8. A suspension system as claimed in any preceding claim and further comprising a wheel hub coupled to the wheel hub knuckle.

9. A suspension system as claimed in any preceding claim, wherein the steering axis is near vertical.

10. A suspension system as claimed in claim 9, wherein the steering axis has a caster angle of less than 20 degrees.

11. A suspension system as claimed in claim 9 or claim 10, wherein the steering axis has a kingpin angle of less than 20 degrees.

12. A suspension system as claimed in any one of claims 9-11, wherein the steering axis has a caster of approximately 7 degrees.

13. A suspension system as claimed in claims 9-12, wherein the steering axis has a kingpin angle of approximately 5 degrees.

14. A wheel hub knuckle comprising a first mounting point connectable to a suspension strut and a second mounting point connectable to a lower control arm, wherein the first mounting point defines a part of a spindle-type joint and the second mounting point defines a part of a ball joint, wherein the spindle-type joint is operable to provide a single degree of rotational freedom of the wheel hub knuckle relative to the strut, the single degree of rotational freedom comprising rotation about an axis passing through a centre of rotation of the ball joint.

15. A wheel hub knuckle as claimed in claim 14, wherein the wheel hub knuckle further comprises a third mounting point, the third mounting point being connectable to a steering assembly.

16. A method of making a wheel hub knuckle 206 as claimed in claim 14 or claim 15, wherein the first mounting point and the second mounting point are produced by a single machining operation.

17. A vehicle comprising a suspension system as claimed in any one of claims 1-13 or a knuckle as claimed in any one of claims 14-16.

18. A vehicle as claimed in claim 17, wherein the vehicle has at least one wheel that is both steerable and driven.

19. A vehicle (500) as claimed in claim 18, wherein the vehicle is a front-wheel drive or four-wheel drive vehicle.

29 05 19

19. A vehicle as claimed in claim 18, wherein the vehicle is a front-wheel drive or fourwheel drive vehicle.

29 05 19

Amendments to the claims have been filed as follows

1. A suspension system (200) for a vehicle comprising:

a wheel hub knuckle (206), a suspension strut (202), a lower control arm (204) and a steering 5 assembly;

the wheel hub knuckle rotatably coupled to the strut utilising a first coupling at a first location and coupled to the lower control arm utilising a second coupling comprising a ball-type joint (218) at a second location, the wheel hub knuckle being coupled to the steering assembly at a third location,

10 wherein the first coupling provides a single degree of rotational freedom of the wheel hub knuckle relative to the strut, and the steering assembly is operable to rotate the wheel hub knuckle about a steering axis (222) passing through the first location and the second location.

2. A suspension system as claimed in claim 1, wherein the first coupling comprises a 15 spindle-type coupling (207).

20 4. A suspension system as claimed in any preceding claim, and further comprising an anti-roll bar (228) coupled to the strut, wherein the anti-roll bar is arranged to limit axial rotation of the strut relative to the vehicle body.

5. A suspension system as claimed in any preceding claim, wherein the strut comprises 25 an integral damper (208).

6. A suspension system as claimed in claim 5, wherein the strut further comprises a spring (210).

30 7. A suspension system as claimed in any preceding claim, wherein the lower control arm is rotatably couplable to the vehicle body at a fourth location remote from the second location.

8. A suspension system as claimed in any preceding claim and further comprising a wheel hub (214) coupled to the wheel hub knuckle (206).

14. A wheel hub knuckle (206) comprising a first mounting point connectable to a suspension strut (202) and a second mounting point connectable to a lower control arm (204), wherein the first mounting point defines a part of a spindle-type joint (207) and the second mounting point defines a part of a ball joint (218), wherein the spindle-type joint (207) is operable to provide a single degree of rotational freedom of the wheel hub knuckle (206) relative to the strut (202), the single degree of rotational freedom comprising rotation about an axis passing through a centre of rotation of the ball joint (218), and wherein the wheel hub knuckle (206) further comprises a third mounting point, the third mounting point being connectable to a steering assembly.

15. A method of making a wheel hub knuckle (206) as claimed in claim 14, wherein the first mounting point and the second mounting point are produced by a single machining operation.

16. A method of making a wheel hub knuckle (206) as claimed in claim 14, wherein the first mounting point and the second mounting point are produced by multiple machining operations.

17. A vehicle (500) comprising a suspension system as claimed in any one of claims 1-13 or a knuckle as claimed in any one of claims 14-16.

18. A vehicle (500) as claimed in claim 17, wherein the vehicle has at least one wheel that is both steerable and driven.