GB2564422A - Steering linkage - Google Patents

Abstract

A steering system 1 for a vehicle rotationally coupling the steering wheel 2 to the steering box 3. The steering linkage 4 has a first shaft 9 coupled to the steering wheel, a second shaft 14 adapted to be coupled to the steering box, and a flexible transmission loop 18 that rotationally couples the first shaft to the second shaft. Rotation from the steering wheel may be transmitted to the steering linkage via a wheel shaft 10, and from the linkage to the steering box via connecting shafts 15, 16. Preferably, connections are made with universal joints 11. The flexible loop may be a toothed or friction belt, or a chain. Therefore the first and second shafts could include pulleys 13, 17 or sprockets (23, 24, Fig.4), respectively. A biased tensioner 20 may be present, as well as an idler 19. The steering wheel could be disposed closer to the vehicle front end than the front wheels, and the loop may be arranged around a chassis member.

Description

Steering Linkage

Field of the Invention

The present invention relates to a steering linkage for coupling a steering wheel to a steering box, and to a vehicle comprising a steering linkage.

Background

Road vehicles typically have a steering column that couples the steering wheel to the steering box, which in turns actuates movement of the front wheels to direct the vehicle during use. A steering box usually includes a steering gear and other linkages for moving the wheels in response to rotational input, and may be power assisted by hydraulic or electric actuators. Typically the steering column includes a number of rotating shafts linked together by universal joints so that the shafts transmit rotation of the steering wheel to the steering box for steering the wheels.

Summary of the Invention

In accordance with some embodiments, there is provided a steering linkage for coupling a steering wheel to a steering box, the steering linkage comprising: a first shaft adapted to be coupled to said steering wheel, a second shaft adapted to be coupled to said steering box, and a flexible transmission loop that rotationally couples the first shaft to the second shaft so that rotation of said steering wheel is transmitted to said steering box.

In some examples, the flexible transmission loop comprises a belt. The belt may comprise a toothed belt. Alternatively, the belt may comprise a friction belt.

The first shaft may comprise a pulley and the second shaft may comprise a pulley. At least one of the pulleys comprises a flange. Alternatively, the pulley may include a guides or a runner arranged to prevent the belt from coming off the pulley.

In alternative examples, the first shaft comprises a sprocket and the second shaft comprises a sprocket, and the flexible transmission loop comprises a roller chain.

The steering linkage may further comprise a tensioner arranged to tension the flexible transmission loop. The tensioner may comprise a biasing member arranged to maintain tension in the flexible transmission loop.

In an alternative example, the pulley of the first shaft and/or the pulley of the second shaft may comprise a tensioning mechanism arranged to maintain tension in the belt.

In addition, the steering linkage may further comprise an idler arranged such that the flexible transmission loop passes over the idler.

The steering linkage may further comprise a coupling shaft that couples the first shaft to said steering wheel. The steering linkage may further comprise a universal joint or a constant velocity joint that couples the first shaft to the coupling shaft. In addition, the steering linkage may further comprise at least one coupling shaft that couples the second shaft to said steering box, and the steering linkage may further comprise a universal joint or a constant velocity joint that couples the second shaft to the at least one coupling shaft.

In some examples, the first shaft is parallel to the second shaft.

According to other embodiments of the invention, there is also provided a vehicle comprising a steering wheel, a steering box, and the steering linkage described above.

The vehicle may comprise a chassis having a front end and a rear end, front wheels disposed proximate the front end, and rear wheels disposed proximate the rear end, and the steering box maybe adapted to steer the front wheels. The steering wheel may be disposed closer to the front end than the front wheels.

The flexible transmission loop maybe arranged to loop around a chassis member.

The chassis may also have a cross direction that is perpendicular to a direction between the front end and the rear end of the chassis, and the steering box may be offset relative to the steering wheel in the cross-direction.

In some examples, the vehicle is a road vehicle. In some examples, the vehicle is a commercial vehicle, for example a goods vehicle such as a heavy goods vehicle. In other examples, the vehicle is a car, van, truck, or bus. The vehicle maybe a hybrid, range-extended, and/or electric vehicle.

Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. l shows a steering system for a vehicle, including a steering linkage; FIG. 2 shows a perspective view of the steering system of FIG. l; FIG. 3 shows a perspective view of the steering linkage of FIG. l and FIG. 2; and, FIG. 4 shows an alternative steering linkage, including a roller chain.

Detailed Description

As illustrated in FIG. l, the steering system l includes a steering wheel 2 and a steering box 3. The steering wheel 2 is located in the front of the vehicle, where the driver is located, and the steering box 3 is located in the undercarriage of the vehicle. The steering linkage 4 transmits rotational movement of the steering wheel 2 to the steering box 3. The steering box 6 actuates steering movement of the wheels 6 by pushing and/or pulling on a part of the wheel 6 or wheel carrier (not shown) to pivot the wheels.

The steering box 3 maybe of any type, for example the steering box may have a ‘rack and pinion’ arrangement that translates rotational input into sideways movement of a steering rack to move the wheels 6. Alternatively, the steering box 3 may a ‘worm and sector’ type, or a ‘screw and nut’ type. Each of these types of steering box 3 are known by the skilled person, and so detailed description is omitted. In addition, the steering box 3 maybe power assisted. That is, the steering system 1 may include a hydraulic or electric system (not shown) that applies a force to assist movement of the steered wheels 6. A vehicle typically has a chassis with front wheels and rear wheels, and the front wheels are usually actuated by the steering system 1 to determine the direction of the vehicle. The steering system 1 may act to move the front wheels 6 of the vehicle. However, the steering linkage 4 described herein could alternatively be used to move the rear wheels, or other wheels of a vehicle, and can be used for two-wheel or four-wheel steering. In some vehicles, particularly large goods vehicles, more than one wheel on each side of the vehicle is steered. In this case, the steering system 1 described herein can act to steer multiple wheels on each side of the vehicle.

In addition, the steering system 1 described herein, particularly the steering linkage 4, may be used in any vehicle, for example a car, van, bus, truck, lorry, or other vehicle. For reasons explained further hereinafter, the steering linkage 4 disclosed herein may be particularly advantageous when used in a goods vehicle, for example a truck or a heavy goods vehicle. The vehicle may have any kind of drive train. For example, the vehicle may have a conventional internal combustion engine, an electric range extender, an electric motor, or any combination of these.

For convenience, in the described examples the steering box 3 is a ‘rack and pinion’ steering box 3 that is adapted to move the steering arms 5 sideways in response to rotational input, as illustrated in FIG. 2. The steering arms 5 are coupled to the wheels 6 or wheel carriers (not illustrated), so that the wheels 6 pivot in response to the sideways movement of the steering arms 5.

As illustrated in FIGS. 1 to 3, the steering linkage 4 comprises a first shaft assembly 7 to which the steering wheel 2 is mounted. The first shaft assembly includes at least a first shaft 9. In the illustrated example, the first shaft assembly 7 also includes a steering wheel shaft to, to which the steering wheel 2 is mounted, and a universal joint 11 that couples the first shaft 9 to the steering wheel shaft 10.

The first shaft 9 includes at least one bearing seat 12, and in the illustrated example the first shaft 9 includes two bearing seats 12. The bearing seats 12 are where the first shaft 9 is rotationally mounted to the chassis of the vehicle. The steering wheel 2 and/or the steering wheel shaft 10 are also rotationally mounted to the chassis of the vehicle to hold them in place. The first shaft assembly 7 is typically housed in the dashboard of the vehicle.

In this example, the first shaft 9 includes a pulley 13. The pulley 13 is mounted to the first shaft 9 at an end of the first shaft assembly 7 distal from the steering wheel 2. In this way, rotation of the steering wheel 2 is transmitted via the steering wheel shaft 10, universal joint 11, and first shaft 9, to the pulley 13.

The steering linkage 4 also includes a second shaft assembly 8 that is coupled to the steering box 3. The second shaft assembly 8 includes at least a second shaft 14. In the illustrated example, the second shaft assembly 8 also includes first and second connecting shafts 15,16 that join the second shaft 14 to the steering box 3. The second shaft 14, first connecting shaft 15 and second connecting shaft 16 are joined together by universal joints 11.

The second shaft 14 includes at least one bearing seat 12 where the second shaft 14 is rotationally mounted to the chassis of the vehicle. In this example, the first connecting shaft 15 is also rotationally mounted to the chassis of the vehicle at bearing seats 12 to hold the first connecting shaft 15 in place. In other examples, the second connecting shaft 16 may additionally or alternatively be rotationally mounted to the chassis of the vehicle. The second shaft assembly 8 is typically disposed in the undercarriage of the vehicle.

In this example, the second shaft 14 also includes a pulley 17. The pulley 17 is mounted to the second shaft 14 at an end of the second shaft assembly 8 distal from the steering box 3. In this way, rotation of the pulley causes rotation of the second shaft 14, which is transmitted via the first and second connecting shafts 15,16, and the universal joints 11, to the steering box 3.

It will be appreciated that a constant velocity (CV) joint maybe used instead of a universal joint in the first shaft assembly 7 and/or in the second shaft assembly 8. A belt 18 couples the first shaft 9 to the second shaft 14 via the pulleys 13,17. In this way, rotation of the steering wheel 2 is transmitted to the steering box 3 via the first shaft assembly 7, the belt 18, and the second shaft assembly 8.

In the illustrated example the first shaft assembly 7 includes a steering wheel shaft 10 disposed between the first shaft 9 and the steering wheel 2. The steering wheel shaft 10 has the advantage of providing a more convenient angle of mounting for the steering wheel 2. However, it will be appreciated that the steering wheel 2 may alternatively be coupled directly to the first shaft 9.

Furthermore, in the illustrated example the second shaft assembly 8 includes first and second connecting shafts 15,16 disposed between the second shaft 14 and the steering box 3. This arrangement has the advantage of permitting imprecise alignment between the second shaft 14 and the steering box 3, and also allows the steering linkage 4 to be routed along a non-linear path through the undercarriage. However, in alternative examples the second shaft 14 maybe directly connected to the steering box 3, or only a single connecting shaft may be disposed between the second shaft 14 and the steering box 3.

As illustrated most clearly in FIGS. 2 and 3 the steering linkage 14 also includes an idler pulley 19. The idler pulley 19 is rotationally mounted the chassis and the belt 18 passes over the idler pulley 19 between the pulley 13 of the first shaft assembly 7 and the pulley 17 of the second shaft assembly 8.

Moreover, as illustrated in FIGS. 2 and 3 the steering linkage 4 also includes a tensioner 20. The tensioner 20 includes a roller 21 that acts on the outside of the belt 18 to deflect the belt 18 inwards, thereby placing the belt 18 under tension. The tensioner 20 ensures adequate tension in the belt 18 during operation. The tensioner 20 may be moveably mounted to the chassis of the vehicle, such that the tensioner 20 can be moved to increase or decrease the tension in the belt 18. Alternatively, the tensioner 20 may be biased towards the belt 18 by a biasing member, for example a spring. In this way, the biasing action of the biasing member ensures that the belt 18 remains under tension, even if the belt were to stretch.

Alternatively, one or both of pulley 13 and pulley 17 may include a tensioner mechanism. For example, one pulley 13,17 maybe slidably mounted and a biasing member arranged to urge the pulley 13,17 away from the other pulley 17,13, so as to maintain tension in the belt 18. Such an arrangement may be lighter and simpler than the tensioner 20 described above.

In a preferred example, the belt 18 is a toothed belt and the pulleys 13,17, including the idler pulley 19, are toothed pulleys. This reduces or eliminates slippage between the belt 18 and pulleys 13,17, providing for accurate steering. However, a V-belt, flat belt, or other type of belt may alternatively be used in the steering linkage 4.

Moreover, in a preferred example the pulleys 13,17, including the idler pulley 19, and the tensioner 20, may include flanges. The flanges may help to retain the belt 18 on the pulleys 13,17,19. However, in other examples the pulleys 13,17,19 may not include flanges. The belt 18 and pulleys 13,17 may also be adapted to have zero backlash. This would ensure accurate steering in both directions, and eliminate slack in the steering wheel 2 when changing direction.

In the alternative example illustrated in FIG. 4, the steering linkage 4 may comprise a roller chain 22 and sprockets 23, 24 in place of the belt 18 and pulleys 13,17 of the examples of FIGS. 1 to 3. As illustrated in FIG. 4, this alternative example has a similar arrangement to the examples of FIGS. 1 to 3. In particular, the steering linkage 4 comprises a first shaft assembly 7 that couples to a steering wheel (2, not shown), and a second shaft assembly 8 that couples to a steering box (3, not shown). The first and second shaft assemblies 7, 8 may include the connecting shafts and bearing seats, as described previously in relation to the examples of FIGS. 1 to 3.

As illustrated in FIG. 4, in this example the first shaft assembly 7 includes a sprocket 23, the second shaft assembly 8 includes a sprocket 24, and a roller chain 22 rotationally couples the two sprockets 23,24 to each other. In this way, rotation of the steering wheel (2, not shown) and first shaft 9 causes rotation to the sprockets 23, 24 and second shaft 14 and second shaft assembly 8, which provides the rotation to the steering box (3, not shown) for steering.

Furthermore, as illustrated, in this example the steering linkage 4 may additionally include an idler sprocket 25 rotationally mounted to the chassis of the vehicle. The roller chain 22 passes over the idler sprocket 25 between the pulleys 23, 24. In addition, the steering linkage 4 of FIG. 4 may additionally include a tensioner sprocket 26. The tensioner sprocket 26 ensures adequate tension in the roller chain 22 during operation. The tensioner sprocket 26 may be moveably mounted to the chassis of the vehicle, such that the tensioner sprocket 26 can be moved to increase or decrease the tension in the roller chain 22. Alternatively, the tensioner sprocket 26 may be biased towards the roller chain 22 by a biasing member, for example a spring. In this way, the biasing force of the biasing member ensures that the roller chain 22 remains in tension.

In the examples described above the first shaft 9 and the second shaft 14 are rotationally coupled via a flexible transmission loop, specifically either a belt 18 or a roller chain 22. However, it will be appreciated that the first shaft 9 and the second shaft 14 can be rotationally coupled via other flexible transmission loops, for example a cable or rope.

As illustrated in FIG. 1, the steering box 3 is located beneath, and rearward of, the steering wheel 2. This is a common arrangement in goods vehicles, such as trucks, and the steering linkage 4 described herein is particular advantageous when the steering box 3 and steering wheel 2 are in such an arrangement because the steering linkage 4 can include ninety degree bends (i.e. between the first shaft 9 and belt 18 or roller chain 22, and between the second shaft 14 and belt 18 or roller chain 22), which allows the steering linkage 4 to be compact. Furthermore, the size of the steering linkage 4 in the forward direction, i.e. towards the front of the vehicle, is minimised, allowing for the driver to be sat relatively closer to the front of the vehicle.

Moreover, the belt 18 or chain 22 arrangement is also advantageous in vehicles in which the steering wheel 2 is located high relative to the steering box 3, because the belt 18 or chain 22 can easily be arrange to extend across a large vertical distance.

The steering linkage 4 described herein is preferable to a typical arrangement of only shafts that transmit the rotation from the steering wheel 2 to the steering box 3 because the belt 18 or roller chain 22 is lighter, more compact, and can be more easily routed around other parts of the vehicle. For example, a belt 18 or roller chain 22 can be looped around other parts of the vehicle (e.g. chassis member). The belt 18 or chain 22 can also easily be angled across the vehicle chassis, meaning that the steering box 3 does not have to be in alignment with the steering wheel 2.

Furthermore, if the vehicle were in a crash the belt 18 or roller chain 22 would detach from the pulleys 13,17 or sprockets 23, 25 and prevent any displacement of the steering box 3 causing displacement of the steering wheel 2. In one particular example, in the case of a frontal collision, the lack of a steering column means there is less chance of the steering wheel 2 being displaced towards the driver. The arrangement of the steering linkage 4 described means that the belt 18 or roller chain 22 is coincident with the driver’s legs, reducing the risk or a rigid member causing injury during a frontal impact.

Moreover, the steering linkage 4 described herein eliminates the need for bevel gears, which are often used in steering columns. Bevel gears need regular maintenance, can wear quickly, and inevitably result in some slack in the steering, and so the steering linkage 4 described herein is advantageous in comparison to such an arrangement.

Furthermore, if the steering linkage includes a belt 18, as per the examples of FIGS. 1 to 3, the belt will act to absorb and dampen vibrations in the steering box 3, and thereby reduce their transmission back to the steering wheel 2.

Another advantage of the steering linkage 4 described herein is that the steering ratio can easily and quickly be altered by selecting the sizes of the pulleys 13,17 or sprockets 23, 25. In comparison, a conventional arrangement of shafts can only provide 1:1 transmission of the rotation of the steering wheel to the steering box, and so additional gearing is often needed in the steering box.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) maybe practiced and provide for a superior steering linkage. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications maybe made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

Claims (22)

Claims

1. A steering linkage for coupling a steering wheel to a steering box, the steering linkage comprising: a first shaft adapted to be coupled to said steering wheel, a second shaft adapted to be coupled to said steering box, and a flexible transmission loop that rotationally couples the first shaft to the second shaft so that rotation of said steering wheel is transmitted to said steering box.

2. The steering linkage of claim 1, wherein the flexible transmission loop comprises a belt.

3. The steering linkage of claim 2, wherein the belt comprises a toothed belt.

4. The steering linkage of claim 2, wherein the belt comprises a friction belt.

5. The steering linkage of any of claims 2 to 4, wherein the first shaft comprises a pulley and the second shaft comprises a pulley.

6. The steering linkage of claim 5, wherein the at least one of the pulleys comprises a flange.

7. The steering linkage of claim 1, wherein the first shaft comprises a sprocket and the second shaft comprises a sprocket, and wherein the flexible transmission loop comprises a roller chain.

8. The steering linkage of any preceding claim, further comprising a tensioner arranged to tension the flexible transmission loop.

9. The steering linkage of claim 8, wherein the tensioner comprises a biasing member arranged to maintain tension in the flexible transmission loop.

10. The steering linkage of any preceding claim, further comprising an idler arranged such that the flexible transmission loop passes over the idler.

11. The steering linkage of any preceding claim, further comprising a coupling shaft that couples the first shaft to said steering wheel.

12. The steering linkage of claim 11, further comprising a universal joint or constant velocity joint that couples the first shaft to the coupling shaft.

13. The steering linkage of any preceding claim, further comprising at least one coupling shaft that couples the second shaft to said steering box.

14. The steering linkage of claim 13, further comprising a universal joint or constant velocity joint that couples the second shaft to the at least one coupling shaft.

15. A vehicle comprising a steering wheel, a steering box, and the steering linkage of any preceding claim.

16. The vehicle of claim 15, further comprising a chassis having a front end and a rear end, front wheels disposed proximate the front end, and rear wheels disposed proximate the rear end, and wherein the steering box is adapted to steer the front wheels.

17. The vehicle of claim 16, wherein the steering wheel is disposed closer to the front end than the front wheels.

18. The vehicle of any of claims 16 to 17, wherein the flexible transmission loop is arranged to loop around a chassis member.

19. The vehicle of any of claims 16 to 18, wherein the chassis has a cross direction that is perpendicular to a direction between the front end and the rear end of the chassis, and the steering box may be offset relative to the steering wheel in the crossdirection.

20. The vehicle of any of claims 15 to 19, wherein the vehicle is a road vehicle.

21. The vehicle of any of claims 15 to 20, wherein the vehicle is a commercial vehicle, for example a goods vehicle such as a heavy goods vehicle.

22. The vehicle of any of claims 15 to 21, wherein the vehicle is a hybrid, range-extended, and/or electric vehicle.