WO2018064724A1

WO2018064724A1 - Steering system

Info

Publication number: WO2018064724A1
Application number: PCT/AU2017/051086
Authority: WO
Inventors: Wayne John Brown
Original assignee: Waybro Pty Ltd
Priority date: 2016-10-05
Filing date: 2017-10-05
Publication date: 2018-04-12

Abstract

A steering system for a vehicle, preferably a crop harvesting vehicle such as a sugar cane harvester, including a frame mounted to, or integral with, the vehicle and two wheel assemblies, each wheel assembly comprising a wheel rotatably mounted to a linkage, and a wheel actuator configured to turn the wheel relative to the linkage. The wheel assemblies are mounted to the frame via the linkage and at least one linkage actuator is configured to manoeuvre the linkages such that a distance between the wheels is varied.

Description

STEERING SYSTEM

FIELD OF THE INVENTION

[0001 ] The invention relates to a steering system for a vehicle. In particular, the invention relates, but is not limited, to a steering system for a harvester, or the like, that has two individually steerable wheels that are able to be moved apart and rotated on parallel axes.

BACKGROUND TO THE INVENTION

[0002] Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge.

[0003] Many land vehicles have steering systems that enable the vehicle to change course. A common consideration for vehicular steering systems is the turning radius, also known as a turning circle. The turning radius is often related to the angle at which the steering wheels can rotate relative to centreline of the vehicle. This angle is usually limited by physical restrictions, such as the space available adjacent the wheel and the mechanics required to be able to move the wheel as desired. Some vehicles have width limitations due to their intended use and in the case of very narrow vehicles this can further limit the available space for angular movement of the wheel during steering.

[0004] In some vehicular applications, such as harvesters, the angle of the steering wheels can be highly restricted, having a lock to lock rotation of approximately only 15°.

[0005] Some vehicles that are capable of turning in location effectively have a zero or near zero turning radius. Such vehicles include tracked vehicles such as excavators or tanks and vehicles where the steered wheels can be arranged on separate radial axes. However, such vehicles require very specific drive arrangements that are not suitable for many applications.

[0006] Articulated steering allows vehicles to have a tighter turning radius, but suffer from other problems such as, for example, tipping over on hilly terrain during oscillation of the front portion of the vehicle opposing the back portion of the vehicle trying to turn.

OBJECT OF THE INVENTION

[0007] It is an aim of this invention to provide a steering system which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides a useful commercial alternative.

[0008] Other preferred objects of the present invention will become apparent from the following description.

SUMMARY OF INVENTION

[0009] In one form, although it need not be the only or indeed the broadest form, there is provided a steering system for a vehicle, the steering system comprising:

a frame mounted to, or integral with, the vehicle; and

two wheel assemblies, each wheel assembly comprising a wheel rotatably mounted to a linkage, and a wheel actuator configured to turn the wheel relative to the linkage;

wherein the wheel assemblies are mounted to the frame via the linkage and at least one linkage actuator is configured to manoeuvre the linkages such that a distance between the wheels is varied. [0010] Preferably the linkages are rotatably mounted to the frame. Preferably rotation of the linkages relative to the frame varies the distance between the wheels. Preferably the linkages comprise elongate members. Preferably the linkages comprise a first end mounted to the frame. Preferably the linkages comprise a second end mounted to the wheel. Preferably the second ends of the linkages move away or towards each other during actuation of the at least one linkage actuator.

[001 1 ] Preferably the angle of the linkages relative to the frame is varied relative to the frame by the at least one linkage actuator. Preferably each linkage as an associated linkage actuator. Preferably the linkage actuators are arranged in an opposed configuration. Preferably the linkages move between a first position that corresponds to a drive position and a second position that corresponds to a turning position.

[0012] Preferably one or more of the wheel actuators and the at least one linkage actuator comprise linear actuators. Preferably the actuators comprise a movable portion that extends and retracts relative to non-movable portion. Preferably the actuators are cylinder actuators that are actuated by a fluid. Preferably the actuators are hydraulic cylinders actuated by a hydraulic fluid.

[0013] Preferably there are two hydraulic wheel cylinders and two hydraulic actuator cylinders. Preferably the wheel cylinders are configured such that when the wheels are straight and parallel to a longitudinal axis of the vehicle that they are at an approximately 50% stroke. Preferably the linkage cylinders have a displacement that is approximately 50% of the displacement of the actuator cylinders. Preferably steering cylinders are out of phase such that as one steering cylinder increases in stroke the other steering cylinder decreases in stroke.

[0014] Preferably the cylinders are configured such that hydraulic fluid displaced from the steering cylinders activates the linkage cylinders. Preferably the linkage cylinders are in phase such that both linkage cylinders increase and decrease in stroke together. Preferably steering cylinders and linkage cylinders are configured such that as one steering cylinder actuates from approximately 50% stroke to approximately 0% stroke the other steering cylinder actuates from approximately 50% stroke to approximately 100% stroke and the linkage actuators actuate from approximately 0% stroke to approximately 100% stroke.

[0015] Preferably a proximity switch is configured to activate a circuit selector that changes the flow of hydraulic fluid from the steering cylinders to the linkage cylinders depending on the desired wheel angle. Preferably the proximity switch is configured to actuate as the steering cylinders pass approximately 50% stroke.

[0016] Preferably each wheel assembly comprises a wheel axle and a steering axle. Preferably each wheel comprises a wheel hub assembly comprising the wheel axle. Preferably the steering axle is transverse to the wheel axle. Preferably the steering axle is perpendicular to the wheel axle. Preferably the wheel axle allows rotation of the wheel relative to the linkage.

[0017] Preferably the steering axle comprises a stator and a rotor with one of the stator and rotor being affixed to the linkage and the other of the stator and rotor bring affixed to the wheel hub assembly of the wheel. Preferably the steering axle is connected to the wheel actuator such that actuation of the steering actuator angles the wheel relative to the linkage.

[0018] Preferably the steering axle comprises a pivot member. Preferably the wheel actuator is mounted to the pivot member. Preferably the steering actuators and wheel actuators are configured to be able to rotate the wheels by at least 30°, preferably by at least 45°, more preferably by more than 50°, and even more preferably by around 60° lock to lock rotation.

[0019] In another form, there is provided a vehicle comprising a steering system as hereinbefore described. Preferably the vehicle is an agricultural vehicle, and even more preferably the vehicle is a harvester. Preferably the steering system is located at a rear end of the vehicle. Preferably a drive assembly including drive wheels is located at a front end of the vehicle. Preferably the vehicle is less than 2m wide, more preferably less than 1 .8m wide, and even more preferably about 1 .6m wide. Preferably the wheel base of the vehicle is less than 1 .6m, more preferably less than 1 .4m, and even more preferably about 1 .3m.

[0020] Further features and advantages of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021 ] By way of example only, preferred embodiments of the invention will be described more fully hereinafter with reference to the accompanying figures, wherein:

[0022] Figure 1 illustrates a side elevation view of a harvester vehicle; [0023] Figure 2 illustrates a fear elevation view of the harvester vehicle in figure 1 ;

[0024] Figure 3 illustrates a perspective view of a steering system in a straight position;

[0025] Figure 4 illustrates a top plan view of the steering system of figure 1 in the straight position;

[0026] Figure 5 illustrates a top plan view of the steering system of figure 1 in a partially turned position;

[0027] Figure 6 illustrates a top plan view of the steering system of figure 1 in a fully turned position;

[0028] Figure 7 illustrates a top plan view of a harvester vehicle with the steering system in the straight position; and

[0029] Figure 8 illustrates a top plan view of the harvester vehicle of figure 7 with the steering system in a fully turned position.

DETAILED DESCRIPTION OF THE DRAWINGS

[0030] Figures 1 and 2 illustrate a vehicle, in the form of a harvester 10, having a chassis 12, a rear wheel steering system 100, a front drive wheel system 14, a topper system 16, a crop lifter system 18, a cabin 20, an extraction system 22, and a conveyor system 24. As seen more clearly in figure 2, the wheel steering system 100 comprises two wheels 122 on either side of the harvester 10.

[0031 ] The harvester 10 is considered to be particularly well suited for harvesting 1 metre to 1 .2 metre row cane crops. Hence, it is fairly narrow as shown in figure 2, having a width of only about 1 .6m and a wheel base of only about 1 .3m, to prevent damage to adjacent rows of crop.

[0032] The steering system 100 is shown in greater detail in figures 3 to 6. The steering system 100 has a frame 1 10 which is mounted to the chassis 12 of the harvester 10. Alternatively, the frame 1 10 could be integral with the chassis 12 of the harvester 10. The steering system 100 comprises two wheel assemblies 120, arranged on opposed sides of the frame 1 10.

[0033] Each wheel assembly 120 comprises a wheel 122 rotatably mounted to a linkage 124 via a wheel hub assembly 126, and a wheel actuator 128 configured to turn the wheel at an angle relative to the linkage 124. Each linkage also has a linkage actuator 130 connected between the frame 1 10 and a respective linkage 124. The linkage actuators 130 are configured to manoeuvre the linkages 124 such that a distance between the wheels 122 is varied as shown in figures 4 to 6.

[0034] In further detail, each linkage 124 comprises a first arm 124a and a second arm 124b hingedly connected to the frame 1 10. The first arm 124a is hingedly connected at its other end to a mount 132 of the wheel hub assembly 126 and the second arm 124b is hingedly connected at its other end to a proximal end of a stator portion of a steering axle 134. The steering axle 134 extends upwardly from the wheel hub assembly 126 and a rotor portion of the steering axle 134 (located inside the stator portion) is fixedly connected to the wheel hub assembly 126 at the proximal end of the steering axle 134. The steering axle 134 is arranged substantially perpendicularly to a wheel axle 138 of the wheel hub assembly 126. [0035] At a distal end of the steering axle 134 is a spacing member 136 which extends transverse to, and preferably substantially perpendicular to, an axial axis of the steering axle 134. The spacing member 136 is mounted to the stator portion of the steering axle 134 and provides a spaced apart mount for one end of the steering actuator 128 to be mounted. The other end of the steering actuator 128 is operatively engaged with a pivot member 138 which is in turn affixed to the rotor of the steering axle 134. The spacing member 136, steering actuator 128, and pivot member 138 are configured such that extension and of the steering actuator 128 causes the wheel 122 to turn the wheel at an angle relative to the linkage 124 and such that varying the extension of the steering actuator 128 correspondingly varies the angle of the wheel 122.

[0036] The two wheel assemblies 120 are arranged on opposite sides of the frame 1 10. The two steering actuatorsl 28 are arranged in the same direction and the two steering linkage actuators 130 are arranged in opposed directions (as seen most clearly in figure 6). The linkages 124 are substantially parallel to each other and the frame 1 10 in a straight wheel 122 position (as illustrated in figure 4), and separate from each other at an increasing angle apart as the wheels 122 are angled further away from the straight position to a left or right lock position (as illustrated in figure 6).

[0037] The steering actuators 128 and linkage actuators 130 are hydraulically connected to actuate simultaneously. Specifically, the steering actuators 128 are hydraulically connected to displace hydraulic fluid into the linkage actuators 130. In the forward position, the steering actuators 128 are at 50% stroke (as illustrated in figure 4) and the linkage actuators 130 are at 0% stroke. The displacement of the steering actuators 128 is approximately double that of the linkage actuators 130, such that hydraulic fluid from a 50% stroke movement of the steering actuators 128 is displaced into the linkage actuators 130 to result in a 100% stroke of the linkage actuators.

[0038] Figure 7 illustrates a harvester 10 with a steering system 100 in a straight position where the wheels 122 are aligned with a longitudinal axis of the harvester 10 and figure 8 illustrates the harvester 10 with the steering system 100 turned to steer the harvester 10 to the left by angling the wheels 122 to the longitudinal axis of the harvester 10 and simultaneously spacing the wheels 122 apart which in turn allows the wheels 122 to turn at a much greater angle than would be possible with a fixed distance between the wheels 122.

[0039] In use, the harvester 10 is operated from the cabin 20 by a driver. As with typical vehicle operation, the harvester 10 is steered using a steering wheel inside the cabin 20. When travelling in a straight direction, such as when harvesting a crop in a straight row, the steered wheels 122 are aligned with the longitudinal axis of the harvester as illustrated in figures 1 , 2, 3, 4, and 7.

[0040] As the steering wheel is turned by the operator in the cabin 20, the steering system 100 actuates to angle the wheels 122. Referring specifically to figures 4 to 6, as the steering wheel is turned from the straight position as illustrated in figure 4 to the full lock position illustrated in figure 6, the steering actuators 128 are activated and extend, causing the pivot member 138 to turn the rotor of the steering axle 134 which turns the wheel 122 as shown in figure 5. [0041 ] As the steering actuators 128 are activated, hydraulic fluid is displaced from the steering actuators 128 into the linkage actuators 130, causing the linkage actuators 130 to simultaneously extend. This causes the linkages 124 to push the wheels 122 outward apart from each other, as also shown in figure 5. The more the steering wheel is turned the further the steering actuators 128 turn the wheels 122 and the further apart the linkage actuators 130 separate the wheels 122, until full lock is reached as shown in figure 6. In a preferred embodiment the full angle lock to lock is around 60°. As shown in figures 4 to 5, at all stages during the turning process the wheels 122 remain substantially parallel to each other.

[0042] To turn from one direction (e.g. left or right turning) to the other direction (e.g. right or left turning, respectively) the steering actuators 128 have to come back to 50% displacement which simultaneously brings the linkage actuators 130 back to a fully retracted or 'closed' position. This occurs when the wheels 122 are in the straight position as illustrated in figure 4. In order to continue turning the wheels past the straight position a proximity switch is activated which in turn activates a circuit selector to change the flow of hydraulic fluid to the linkage actuators 130 so that the steering actuators 128 can continue the turning cycle and continue to displace into the linkage actuators 130 to push the linkages 124 outwards again, thereby allowing the wheels 122 to complete the turn from lock to lock.

[0043] Advantageously, the steering assembly 100, and a vehicle such as a harvester 10 having such a steering assembly 100, is able to have both a narrow wheel base and a large steering lock angle. The large steering lock angle provides many manoeuvrability advantages, particularly for vehicles operating in confined spaces. This is considered to be particularly advantageous for harvester vehicles to operate on small farm plots, for end of row crop recovery, and in hill headland fields.

[0044] The hydraulic circuit elegantly allows both the angle of the wheels 122 and the distance between the wheels 122 to be varied simultaneously using the same hydraulic fluid. The proximity sensor and circuit selector allow a seamless transition of hydraulic fluid flow from the steering actuators 128 to the linkage actuators 130 as the wheels go from one turn direction through the straight wheel position to another turn direction.

[0045] The harvester 10 is particularly well suited to harvesting a single row of stick-type sugar cane, where the cane stalks are harvested whole, or substantially whole, and where any leaf or other waste material is stripped from the stalks. The compact nature of the harvester 10 allows easy transportation (e.g. on a trailer) and results in a low-pressure footprint to ensure minimal damage to the field being harvested.

[0046] The invention primarily relates to a steering system 100, and while a harvester 10 as illustrated in figures 1 , 2, 7 and 8 is a preferred application for the steering system 100, it should be appreciated that the steering system 100 could be applied to other harvester types and, indeed, other vehicle types. The steering system 100 is considered to be particularly well suited to the harvester 10 as illustrated but, where the context permits, no limitation is meant thereby.

[0047] In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.

[0048] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

[0049] In this specification, the terms 'comprises', 'comprising', 'includes', 'including', or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

Claims

CLAIMS:

1 . A steering system for a vehicle, the steering system comprising: a frame mounted to, or integral with, the vehicle; and

wherein the wheel assemblies are mounted to the frame via the linkage and at least one linkage actuator is configured to manoeuvre the linkages such that a distance between the wheels is varied.

2. The steering system of claim 1 wherein the linkages are rotatably mounted to the frame such that rotation of the linkages relative to the frame varies the distance between the wheels.

3. The steering system of claim 1 or 2, wherein the linkages comprise elongate members having a first end mounted to the frame and a second end mounted to the wheel, wherein the second ends of the linkages move away or towards each other during actuation of the at least one linkage actuator.

4. The steering system of any one of the preceding claims, wherein the angle of the linkages relative to the frame is varied relative to the frame by the at least one linkage actuator.

5. The steering system of any one of the preceding claims, wherein each linkage as an associated linkage actuator and the linkage actuators are arranged in an opposed configuration.

6. The steering system of any one of the preceding claims, wherein the linkages move between a first position that corresponds to a drive position and a second position that corresponds to a turning position.

7. The steering system of any one of the preceding claims, wherein the one or more of the wheel actuators and the at least one linkage actuator comprise linear actuators.

8. The steering system of claim 7, wherein there are two hydraulic wheel cylinders and two hydraulic linkage cylinders.

9. The steering system of claim 8, wherein the two hydraulic wheel cylinders and two hydraulic linkage cylinders are configured such that when the wheels are straight and parallel to a longitudinal axis of the vehicle that they are at an approximately 50% stroke.

10. The steering system of claim 8 or 9, wherein the linkage cylinders have a displacement that is approximately 50% of the displacement of the actuator cylinders.

1 1 . The steering system of any one of claims 8 to 10, wherein the steering cylinders are out of phase such that as one steering cylinder increases in stroke the other steering cylinder decreases in stroke.

12. The steering system of any one of claims 8 to 1 1 , wherein the cylinders are configured such that hydraulic fluid displaced from the steering cylinders activates the linkage cylinders.

13. The steering system of any one of claims 8 to 12, wherein the linkage cylinders are in phase such that both linkage cylinders increase and decrease in stroke together.

14. The steering system of any one of claims 8 to 13, wherein the steering cylinders and linkage cylinders are configured such that as one steering cylinder actuates from approximately 50% stroke to approximately 0% stroke the other steering cylinder actuates from approximately 50% stroke to approximately 100% stroke and the linkage actuators actuate from approximately 0% stroke to approximately 100% stroke.

15. The steering system of any one of claims 8 to 14, wherein a proximity switch is configured to activate a circuit selector that changes the flow of hydraulic fluid from the steering cylinders to the linkage cylinders depending on the desired wheel angle.

16. The steering system of any one of the preceding claims, wherein each wheel assembly comprises a wheel axle and a steering axle.

17. The steering system of claim 16, wherein each wheel comprises a wheel hub assembly comprising the wheel axle.

18. The steering system of claim 16 or 17, wherein the steering axle is transverse to the wheel axle and wherein the wheel axle allows rotation of the wheel relative to the linkage.

19. The steering system of any one of claims 16 to 18, wherein the steering axle comprises a stator and a rotor with one of the stator and rotor being affixed to the linkage and the other of the stator and rotor bring affixed to the wheel hub assembly of the wheel.

20. The steering system of any one of claims 1 6 to 19, wherein the steering axle is connected to the wheel actuator such that actuation of the steering actuator angles the wheel relative to the linkage.

21 . The steering system of any one of claims 16 to 20, wherein the steering axle comprises a pivot member with the wheel actuator mounted thereon.

22. A vehicle comprising a steering system as claimed in any one of claims 1 to 21 .

23. The vehicle of claim 22, wherein the steering system is located at a rear end of the vehicle.