GB2217272A - Oscillating axle- or oscillating two-part-chassis vehicle - Google Patents

Abstract

A vehicle comprising a first pair of ground engageable wheels carried on a first oscillating member such as an axle which is pivotable about a generally horizontal axis relative to a second oscillating member such as the chassis which carries a second pair of ground engageable wheels and a stabilising system, the stabilising system comprising a fluid operated actuator means, connected between the oscillating members to control oscillation therebetween about said generally horizontal axis, passage means to enable fluid to flow to and from another chamber of the actuator in response to oscillation of the members and valve means to control the flow of fluid along the passage means in a direction to control oscillation between said members. in the preferred embodiment there is provided an oscillating axle 30 attached to the chassis by a pivot 34, 35, control being effected by a pair of hydraulic rams 38, 39 interconnected via suitable circuitry as shown in fig. 3. Valves 42, 43 control the direction of flow and check valves 47, 48 provide resistance to flow and thus oscillation of the axle. <IMAGE>

Description

Title: "\/vehicle" Description of Invention This Invention relctes to a vehicle having a first pair of ground engageable wheels carried on a first oscillating member which is pivotable about a generally horizontal axis e.g. horizontal or inclined to the horizontal 0 up to about 15 relative to a second oscillating member which carries a second pair of ground engageable wheels. The generally horizontal axis permits the pairs of wheels to twist relative to each other when driving over uneven ground so that the pairs of wheels can conform to the shape of the ground.

Such vehicles are known which have at least one of the first and second oscillating members provided by an "oscillating axle". That is, an axle which is connected to the respective chassis part by means of a connection which permits the axle to oscillate relative to the chassis part about a generally horizontal axis e.a. horizontal or inclined to the horizontal up to about 150 to enable the vehicle to travel over rough terrain, the chassis parts being rigid about a generally horizontal axis. Alternatively, the chassis parts themselves mav be connected for pivotal movement about a generally horizontal axis with the wheels being carried by the respective chassis parts without provision for pivotal movement about a generally horizontal axis.

More particularly, but not exclusively, the invention relates to a vehicle comprising a front chassis part and a rear chassis part which are articulated for steering about a generally upright e.g. vertical or inclined to the vertical 0 up to about 100 axis. Such a vehic!e will hereinafter be referred to as "an articulated vehicle".

Particularly when such an articulated vehicle is provided with a loaded work implement which projects forwardly or rearwardly of the chassis parts, stabilisation of the vehicle, especially when cornering by artIculating the front and rear chassis parts relative to one another, is a design consideration.

However, the very nature of such an oscillsttng axle or oscillating chassis parts can contribute to instability of an articulated vehicle, especially on cornering since, particularly when the vehicle has a loaded work implement projecting from the chassis, a moment is Droduced tending to overturn the vehicle.

An object of the invention is to provide a new and improved vehicle.

According to the present invention, we provide a vehicle comprising a first pair of ground engageable wheels carried on a first oscillating member which is pivotable about a generally horizontal axis relative to a second oscillating member which carries a second pair of ground engogeable wheels and a stabilising system, the stabilising system comprising a fluid operated actuator means, connected between the oscillating members to control oscillation therebetween about said generally horizontal axis, passage means to enable fluid to flow to and from a chamber of the actuator in response to oscillation of the members and valve means to control the flow of fluid along the passage means in a direction to control oscillation between said members.

Preferably the actuator means comprises a pair of chambers between which fluid is transferred on oscillation between said members.

The invention is particularly, but not exclusively, for use where the vehicle is an articulated vehicle.

In this case the flow of fluid is controlled so as to at least resist relative pivotal movement between the oscillating members to counteract rising of one oscillating member relative to the other on the same side as the direction in which the one oscillating member has been articulated for steering.

The oscillating members may comprise, in a preferred embodiment, an oscillating axle and an associated chassis part but may comprise two oscillating chassis parts.

!here the oscillating member is an oscillating axle, and the vehicle is an articulated vehicle, the oscillating axle may be provided either on the front or rear chassis part, or both the front and rear axles may be oscillating axles, in which case both the front and rear axles may have a stabilising system if reauired.

The valve means may permit flow of fluid from the actuator chamber against a resistance to fluid flow to control said oscillation.

Alternatively, the valve means may prevent flow of fluid from the actuator chamber to control said oscillation.

Alternatively, the valve means may feed fluid under pressure into the actuator chamber to control said oscillation.

The vehicle may have means to receive a load in which case the resistance produced by the valve means to the free flow of fluid along the passage means, may be adjustable to an extent depending on the load.

It will be appreciated that as the vehicle moves over the ground, particularly when the vehicle is cornering, the load affects stability of the vehicle. Hence by "load" we mean the effect of the load on the stability of the vehicle.

The vehicle may have a boom carrying a loading implement such as forks or a bucket, which boom and loading implement may be operated by a power svstem, such as a fluid operated system, to enable the loading implement to be loaded. However, the invention may be applied to any other type of vehicle which has an oscillating member.

In one arrangement, a single acting fluid operated actuator is provided on each side of the axis of oscillation of the members, and the passage means connects the actuator chambers together so that fluid ejected from one actuator chamber is transferred towards the other actuator chamber and vice-versa.

In an alternative version, a double acting fluid operated actuator may be Drovided on one side only of the axis of oscillation of the member, the passage means connecting the chambers on opposite sides of the actuator together so that fluid ejected from the chamber on one side of the actuator is transferred towards the chamber on the opposite side of the actuatorand vice-versa.

In each case, means may be provided to signal the valve means of the stabilising system to adjust the extent of resistance to the free flow of fluid along the passage means to an extent depending upon the load.

where the vehicle has a fluid operated sYstem to load a loading implement thereof, the signal to the valve means may be derived from the fluid operating system although preferably there is no exchange of fluid between the fluid operated system of the loading implement and the stabilising system. However, alternatively, the signal could be electrical in nature and the valve means of the stabilising system may be responsive to the electrical signal which is itse!f dependent upon the load sensed.

Drefersb!v however, the signal is derived from a fluid operated svstem operable to lift and lower the boom, where provided, to the remainder of the vehicle body.

The valve means may for example comprise a sequencing valve which opens to allow flow in response to a threshold fluid pressure in a part of the passage means between the sequencing valve and an associated chamber to allow controlled flow of fluid along the passage means. The threshold pressure may be fixed by the characteristic of the sequencing valve, but preferably, where the resistance to fluid flow is adjustable by a signal depending on the load, the threshold pressure is changeable to an extent depending on the load. Thus the signal may comprise a pilot signal received from the fluid operating svstem of the load carrying means.

A pair of such sequencing valves may be provided, one associated with each single actuator or each side of the double acting actuator, each valve being responsive to the pilot signal. The valves could of course be contained in a single valve block.

Each valve preferably permits fluid flow in one direction only through the valve, from the respective single actuator or side of the double actuator, there being a by-pass with d check valve associated with each sequenceing valve to permit the free flow of fluid past the valve in an opposite direction to that in which fluid flow is permitted through the respective valve.

The fluid operated system for the boom of the vehicle may comprise at least one actuator, and the pilot signal may be derived directly from a fluid feed line to the actuator.

The invention will now be described with the aid of the accompanying drawings in which: FIGURE I is an illustrative side view of a vehicle which may embody the invention.

FIGURE 2 is a front view of the front axle of the vehicle of Figure 1 showing part of a stabiliser system according to the invention, FIGURE 3 is a diagrammatic illustration of the stabilising system for use with the vehicle shown in Figures I and 2, and FIGURE 4 is a view looking forwards at the rear of a modified front axle.

Referring first to Figure 1, a vehicle 10 of the articulated type has a vehicle body II comprising a front chassis part 12 and a rear chassis part I 3, and a pair of loading arms 14 which together comprise a loading boom, carried on the front chassis part 12.

The vehicle 10 is driven and the loading arms 14 are controlled from within an operator's cab IS which is mounted on the rear chassis part.

The body Il carries two pairs of ground engaging wheels 17,18, wheels 17 being termed hereinafter "the front wheels" being carried on an axle 30 on the front chassis part 12, and the wheels 18, being termed hereinafter "the rear wheels" being mounted on an axle carried by the rear chassis part 13.

An engine to provide power to drive the vehicle 10 and a hydraulic operating system of the vehicle 10, is mounted beneath a bonnet 19.

The loading arms 14 are pivotally mounted at one end at 20 to the front chassis part 12, and carry at an opposite end a loading implement comprising in this example a loading bucket 22. The loading arms 14 can be moved about a pivot 20 by a pair of hydraulic actuators 23 connected in a loader lift arm circuit, although only one of these can be seen in figure 1 of the drawings.

The bucket 22 can be pivoted relative to the loading arm 14 for movement about a generally horizontal axis 25, by a further pair of hydraulic actuctors 26 (only one of which can be seen) mounted between the loading arms 1 4 and the bucket 22.

Thus the vehicle 10 can be loaded and unloaded bv manipulating the arms 14 and bucket 22, as is well known in the art. If desired, any other means for manipulating the arms and the bucket may be provided.

The vehicle 10 can be steered by articulating the front chassis part 12 relative to the rear chassis part 13, about a generally vertical axis 27, by means of linear hydraulic actuctors which are provided to effect this articulation, although alternatively any other hydraulically powered or other slewing means could be provided.

Referring now to Figure 2, there is shown an axle 30, which in use carries the front wheels 17, although the wheels !7 themselves are omitted.

The wheels 17 are mounted on hubs 31 at each end of the axle 30 and the hubs 31 are driven via half shafts within the axle 30 from a crown wheel and pinion gear mounted in a housing 32 of the axle, drive being transmitted thereto from a gearbox G via drive shafts .

The axle 30 is of the oscillating type and is mounted relative to the front chassis part 12 by trunnions 34 received by bushed openings of the chassis front part 12 so that the axle 30 may oscillate about a generally horizontal pivotal axis 35. There is a tendency for this oscillation to permit of overturning of the vehicle in certain circumstances. For example, when the loading bucket 22 is transDorting a load and the chassis parts have been articulated about the axls 27 for steering, the reaction with the ground preventing overturning occurs at the contacting point of the inside rear wheel 18 and the pivot axis 35 at the centre of the axle 30. The load being offset, in the direction of steering, from a projection of a line joining these points, creates a turning moment.

To stabilise this oscillation, a pair of single acting hydraulic actuators 38,3?, are mounted between the axle 30 and the front chassis part 12, one actuator 38 being provided to one side of the axis 35 and the other actuator 39 being provided on the other side of the axis 35. The connections between the actuctors 38,39 and the axle 30 and between the actuctors 38,3a and the front chassis part 12, permit of pivoting movement as the axle 30 oscillates.

Referring now to Figure 3, the actuators 38,39, are each part of an axle stabilising system 40 of the vehicle 10, the actuctors 38,39, being connected by a passage means 41 which permits hydraulic fluid of the system to move from one actuator 38,3?, towards the other 39,38, as the axle oscillates.

However, the free flow of fluid along the passage means 41 is resisted by a resPective sequencing valve 42,43, (e.g. OIL CONTROL LTO. cartridge Model Kilo. VSP-SD-150) one of which is associated with each of the actuctors 38,39.

The valves 42,43, are of the type which open when a threshold pressure is present in a part 41a,41b of the passage means 41 between the respective valves 42,43 and its respective actuator 38,39 sufficient to overcome the force of a spring S. The springs S are in cavities of the valves to which a pilot signal may be fed to assist the springs S and increase the threshold pressure. In this example, the pilot signal is fed to the valves 42,3, from a pilot passage 44 which connects with a feed line 50 which actuates the loader rams 23 to lift the loader arms 14, although the valves 42,43 are constructed so that there is no exchange of fluid between passage 44 and the stsbilising system 40.

Each valve 42,43, has an associated bi-pass circuit 45,46, respectiveiy, with a respective check valve 47,48.

The valves 42,43, only permit fluid flow through the valves in one direction indicated by the arrows, cs hereinafter explained, whereas the check valves 47,48 permit free flow of fluid in a direction opposite the direction of fluid flow permitted through the associated valves 42,43.

Fluid to the stabilising system 40 is provided from a feed line 51 through a pressure reducing valve 60 from a hydraulic pump of the vehicie, when the fluid pressure in the stabiliser system 40 falls below a predetermined limit.

Operation of the stabiliser system 4Q will now be described.

As the vehicle travels, the axle 30 will oscillate and fluid may for example be expelled from actuator 38 as the associated side of the axle rises.

If sufficient pressure is generated in part 41a of the passage means 41, the valve 42 will be opened and so fluid may thus pass from actuator 38 towards actuator 39 by passing first through valve 42, along passage means 41 and through the check valve 48 associated with the valve 43, towards the actuator 39. However even when the valve 42 is open, free flow of fluid is controlled i.e. resisted by the valve 42 to an extent depending on the character of the valve 42. When the axle 30 oscillates so as to retract the piston of the actuator 39 fluid will be expelled from actuator 39 and again if sufficient pressure is generated in the associated part 41 b of the passage means, valve 43 will open and allow restricted flow of fluid towards valve 42, through check valve 47 and towards actuator 38.

However in both cases, the free flow of fluid is controlled by the respective valves 42, 43.

As the vehicle 10 corners, by pivoting the front chassis part 12 relative to the rear chassis part 13, the axle 30 will thus be prevented from freely oscillating about axis 35 relative to the front chassis part 12 due to the resistance to fluid flow due to the threshold pressure required in passage part 41a or 41b to open the respective valve 42,43, and secondly because of the controlled fluid flow along passageway 41 permitted by the respective valve 42, 43, so that the stability of the vehicle 10 compared with a similar vehicle not provided with the stabilising system 40 is considerably improved.As a result, the react on is now taken by the points of contact with the ground of the front and rear wheels 17, 18 and so, depending upon the extent of projection of the loading bucket in front of the front chassis part the above mentioned moment is reduced or acts on the other side of a projection of a line joining these points.

It will be appreciated that as the vehicle is loaded, for example as dirt is loaded into the bucket 22, the pressure in feed lines 50 feeding hydraulic fluid to the actuctors 23 to lift the loading arm 14 will increase. This increase in pressure is transmitted to the pilot feed passage 44 of the stabiliser system 40 and the threshold pressure needed to open the valves 42,43 will thus be increased by an amount depending upon the magnitude of the load.

Thus the rigidity of the oscillating axle 30 relative to the front chassis part 12 will change depending upon the magnitude of the load. The greater the load, the more pressure is required in passage parts 41a,4lb of the passage means to open the valves 42 and 43 and so the more rigid become the actuators 38 and 39 against movement of the oscillating axle 30 relative to the vehicle body 11.

'various modifications may be made without departing from the scope of the invention.

It will be appreciated that although the stabilising system 40 is described in relation to an articulated loading vehicle, the invention may be applied to any other load carrying vehicle, and many other different types of articulated and non-articulated vehicle as required which may have an oscillating axle. In each case, a load sensing means is preferably provided, such as described by virtue of the connections 44,45, to the valves 42,43, or alternatively a pressure sensor for example may be provided to control the opening of valves 42,b3, of the stabilising system 40 and when open, to control the flow of fluid through a passage means which carries fluid ejected f ram one actuator towards another.

As described, the vehicle 10 only has a stabilising system associated with the axle 30 carrying the front ground wheels 17, which is an oscillating axle. The axle carrying the rear ground wheels 18 is rigid. However, in another type of vehicle, both the axles carrying the front wheels 17 and the rear wheels 18 may be of the oscillating type and may each have a stabilising system associated therewith.

Alternatively, if the rear axle were of the oscillating type and the front axle risid, only the rear axle would require a stabilising system.

The stabilising system 40 of the front axle may be responsive to the load carried on the front axle, whereas any stabilising system of the rear axle may be made dependent upon the load carried by the rear axle. Alternatively, the stabilising system of the front and/or rear axles may be dependent upon the load carried by the front or rear axle only, or both of the axles.

It will be appreciated that the axle shown in Figure 2 is diagrammatic only. Whereas preferably in a vehicle such as a vehicle shown at 10 in figure I, the axles carrying both the front and rear wheels 17,18, are driven so that the vehicle is four wheel drive, it will be appreciated, that the stabilising system may be applied to a vehicle in which drive is transmitted through only two wheels so that the hubs 31 may not be driven.

Where the invention is applied to a vehicle which is not of the articulated type, but has an oscillating axle, the hubs 31 of the front wheels or hubs of the rear wheels may be movable to effect steering of the vehicle.

Although as described, sequencing valves 42,43, have been provided in the stabilising system 40, if desired, other types of valve may be provided which can vary the resistance to fluid flow in the passage means 41 by an amount depending upon the magnitude of the load. For example, electrically assisted valves may be provided, and a sensing means such as a load sensor or strain gauge, may be provided which provides an electrical signal in response to the load, which signal is transmitted to the valves which thus vary the resistance to the flow through the passage means 41 of the stabilising system.

With alternative types of valve 42,43, the check valves 47,48 and bipass circuits 45,'6, may not be required.

Instead of a pair of single acting actuctors, one either side of the oscillating axis, a double acting actuator could be provided on one side of the axis only, zn which case, the passage means may connect the opposite sides of the double acting actuator so that the stabilising system could operate substantially as described above but with suitable arrangements provided to compensate for the different volumes of the two chambers due to the presence of a piston rod in one chamber. For example, a valve means may be associated with each side of the double acting actuator rather than with each of a pair of single acting actuators.

Although the actuctors 38 and 3? have been described as being single acting, in another application, a pair of double acting actuctors may be provided which enable the position of the pistons relative to the cylinders of the axles to be set rigid for example when the vehicle is stationary and the loading arms 14 or excavating arm of the vehicle is in use.

If desired the axle configuration shown in Figure a may be used instead of the axle shown in Figure 2.

In the embodiment described, the stabilising system is applied to an oscillating member comprising an axle. Where rigid axles are provided on an articulated vehicle, the stabilising system mav be provided between the oscillating chassis parts in which case the oscillating member would be one of the chassis parts, and the actuator or actuators would be connected between the chassis parts. If desired each of the first and second pairs of wheels may be carried on an oscillating member which can pivot relative to an associated chassis part and the chassis parts mav themselves be pivotally interconnected about a generally horizontal axis in which case an appropriate number of stabilising systems may be provided for each pair of oscillating parts.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (28)

CLAIMS:

1. A vehicle comprising a first pair of ground engageable wheels carried on a first oscillating member which is pivotable about a generally horizontal axis relative to a second oscillating member which carries a second pair of ground engageable wheels and a stabilising system, the stabilising system comprising a fluid operated actuator means, connected between the oscillating members to cdntrol oscillation therebetween about said generally horizontal axs, passage means to enable fluid to flow to and from a chamber of the actjator in response to oscillation of the members and valve means to control the flow of fluid along the passage means in a direction to control oscillation between said members.

2. A vehicle according to Claim I wherein the fluid operated actuator means comprises a pair of chambers between which fluid is transferred on oscillation between said members.

3. A vehicle according to Claim I or Claim 2 wherein the vehicle is an articulated vehicle.

4. A vehicle according to Claim 3 wherein the flow of fluid is controlled so as to at least resist relative pivotal movement between the oscillating members to counteract rising of one oscillating member relative to the other on the same side as the direction in which the one oscillating member has been articulated for steering.

5. A vehicle according to any one of the preceding claims wherein the oscillating members comprise an oscillating axle and an associated chassis part.

6. A vehicle according to any one of Claims I to 5 wherein the oscillating members comprise two oscillating chassis parts.

7. A vehicle according to Claim 5 when dependent on Claim 3 or Claim 4 wherein the oscillating axle is provided either on the front or rear chassis part.

8. A vehicle according to Claim 5 when dependent on Claim 3 or Claim 4 wherein both the front and rear axles are oscillating axles and both the front and rear axles have a stabilising system.

9. A vehicle according to any one of the preceding claims wherein the valve means permit flow of fluid from the actuator chamber against a resistance to fluid flow to control said oscillation.

10. A vehicle according to anv one of Claims I to 8 wherein the valve means prevent flow of fluid from the actuator chamber to control said oscillation.

1. A vehicle according to any one of the preceding claims wherein the vehicle has means to receive a load and the resistance produced by the valve means to the free flow of fluid along the passage means, is adjustable to an extent depending on the load.

12. A vehicle according to any one of the preceding claims wherein the vehicle has a boom carrying a loading implement such as forks or a bucket, which boom and loading implement may be operated by a power system, such as a fluid operated system, to enable the loading implement to be loaded.

13. A vehicle according to any one of the preceding claims wherein a single acting fluid operated actuator is provided on each side of the axis of oscillation of the members, and the passage means connects the actuator chambers together so that fluid ejected from one actuator chamber is transferred towards the other actuator chamber and vice-versa.

14. A vehicle according to any one of Claims I to 12 wherein a double acting fluid operated actuator is provided on one side onlv of the axis of oscillation of the member, the passage means connecting the chambers on opposite sides of the actuator together so that fluid ejected from the chamber on one side of the actuator is transferred towards the chamber on the opposite side of the actuatorand vice-versa.

15. A vehicle according to Claim 13 or Claim 14 wherein means are provided to signal the valve means of the stabilising system to adjust the extent of resistance to the free flow of fluid along the passage means to an extent depending upon the load.

16. A vehicle according to Claim 15 wherein the vehicle has a fluid operated system to load a loading implement thereof, and the signal to the valve means is derived from the fluid operating system.

17. A vehicle according to Claim i6 wherein there is no exchange of fluid between the fluid operated system of the loading implement and the stabilising system.

18. A vehicle according to Claim ló wherein the signal is electrical and the valve means of the stabilising system are responsive to the electrical signal which is itself dependent upon the load sensed.

19. A vehicle according to Claim 16 or Claim 17 wherein the signal is derived from a fluid operated system operable to lift and lower the boom, relative to the remainder of the vehicle body.

20. A vehicle according to any one of Claims 2 to 19 wherein the valve means comprises a sequencing valve which opens to allow flow in response to a threshold fluid pressure in a part of the passage means between the sequencing valve and an associated chamber to allow controlled flow of fluid along the passage means.

21. A vehicle according to Claim 20 wherein the threshold pressure is fixed by the characteristic of the sequencing valve.

22. A vehicle according to Claim 20 wherein the resistance to fluid flow is adjustable by a signal depending on the load, and the threshold pressure is changeable to an extent depending on the load.

23. A vehicle according to Claim 22 wherein the signal comprises a pilot signal received from the fluid operating system of the load carrying means.

24. A vehicle according to Claim 23 when dependent on Claim 19 wherein the fluid operated system for the boom of the vehicle comprises at least one actuator and the pilot signal is derived directly from a fluid feed line to the actuator.

25. A vehicle according to any one of Claims 20 to 24 wherein a pair of sequencing valves is provided, one associated with each single actuator or each side of the double acting actuator.

26. A vehicle according to any one of Claims 20 to 24 wherein each valve permits fluid flow in one direction only through the valve, from the respective single actuator or side of the double actuctor, there being a by pass with a check valve associated with each sequencing valve to permit the free flow of fluid past the valve in an opposite direction to that in which fluid flow is permitted through the respective valve.

27. A vehicle substant.ally as hereinbefore described with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

28. Any nove! feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.