GB2353980A - Levelling device - Google Patents

Abstract

A levelling device fitted to a vehicle, such as a caravan, utilises the axle and suspension system and modified front support (jockey) wheel to rotationally alter the roll and pitch angles of the chassis relative to the ground. Axle mechanisms are linked so that as one wheel moves upwardly the other moves downwardly, giving a rotating action to the chassis and avoiding the necessity of lifting and lowering the whole mass of the vehicle. An analogue or digitally based control system with integral tilt sensors is utilised to operate the system, and additionally can subsequently operate motorised corner steadies with ground contact sensors.

Description

LEVELLING DEVICE This invention relates to a levelling device for vehicles

when stationary, such as caravans, mobile food trailers, portable stages, and other types of vehicle, both towed and motorised.

In order to use caravans and other towed vehicles correctly, they must be levelled, normally with the use of a manual system involving some trial and error. Existing levelling designs using an automatic control system utilise a series of hydraulic or pneumatic jacks which lift the chassis at it's comers in varying degrees, resulting in a level chassis.

These systems have several disadvantages:

Structural enhancement of the chassis/bodywork is normally necessary in order to take the large resultant forces at the comers of the vehicle.

The system must be of sufficient power to lift the full weight of the vehicle.

Hydraulic and pneumatic systems are potentially expensive and complicated to implement.

Hydraulic systems can leak and be oily.

Pneumatic systems can leak and are more hazardous.

This invention provides a levelling system of a type which does not suffer from any of the disadvantages stated above, instead utilising a linked mechanical system which provides levelling via an unusual rotational approach.

Accordingly, this invention provides a levelling system for a vehicle, having first and second wheels supported by respective suspension units on the vehicle, the system comprising a drive unit mechanically linked and acting on the suspension units, such that, in use, the drive unit causes the first wheel to move upwardly, and the second wheel to move correspondingly downwardly, resulting in an angular rotation of the chassis in the side to side plane (roll), whilst avoiding lift of the mass of the vehicle. A modified motorised front support wheel provides raising and lowering of the front of the chassis, resulting in an angular rotation of the chassis in the front to back plane (pitch), whilst avoiding lift of the mass of the vehicle. An electronic device provides automatic control of the complete system. The electronic control system can also operate motorised comer steadies initiated either manually or automatically after the levelling process has been completed.

Many suspension systems can be used with this invention, such as the trailing arm design, the strut type design, the wishbone design, etc. The specific mechanism of the drive system will differ for different suspension types. For example, in suspension systems requiring lateral movement (such as the wishbone and strut designs), a rack and pinion type mechanism can be utilised. In systems requiring rotation movement (such as the trailing arm design), a rotational gearing system can be utilised.

Two embodiments of the invention will now be described by way of example (using a trailing arm suspension in this case) with reference to the accompanying drawings in which:

Figure I is a view of a typical towed chassis (without any superfluous bodywork shown), incorporating the additional systems for the invention; Figure 2 is a view of one suitable mechanical system (using rubber torsional shear springs/dampers) for suspension adjustment in the axle; Figure 3 is a view of a second suitable mechanical system (using torsion bars and gas dampers - gas dampers not shown); Figure 4 is a detailed view of the system of Figure 2; Figure 5 is an external view of the motorised front support wheel; Figure 6 is a cross-section of the motorised front support wheel; Figure 7 is a front view of the chassis and system, when activated on a slope:

Figure 8 is a side view of the chassis and system, when activated on a slope; Figure 9 is a simplified block diagram of a suitable analogue control system used to automatically operate the device; and Figure 10 is a simplified block diagram of a suitable digital control system used to automatically operate the device, including comer steady circuitry.

Referring now more particularly to the drawings in which like reference numerals denote like or equivalent parts, particularly in Figures 2 and 3, the system comprises a conventional chassis [I] with modified axle [2] (or double axle), modified front support wheel [3], and wheels [4,5].

The geared motor [6] is attached to the outer casing of the gearbox [22], lid (not shown) and/or axle casing [21] (attachments not shown). The said geared motor and centrally mounted one in - two out gearbox [7] provide anticlockwise rotation of one output shaft [8] and clockwise rotation of the other [9], resulting in an anticlockwise rotation of one suspension arm/hub [ 10] and clockwise rotation of the other [ 11], resulting in a raising of one wheel [4] and a simultaneous lowering of the other [5]. The net resultant vertical movement in the side to side plane of the vehicle is zero, instead exhibiting a clockwise or anticlockwise rotational movement. Bearings [12,13,14,15] are incorporated to support and align the system and vehicle. Also shown in Figures 2 and 3 are the suspension units; the specific embodiments use a rubber system [ 16,17] (Figure 2), and a torsion bar system [ 18,19] (Figure 3).

The central components of the axle system (Figure 4) incorporate the said bearings [ 13,14], supported by fixings [20] and the outer casing [21]. The centre gearbox is constructed with an outer casing [22] and lid (not shown) and inner supports [23]. The gearbox lid or casing, and axle outer casing may optionally be permanently fixed together by way of either a single piece construction or with weld seams. Crown wheels [24,25] are driven via a central bevel gear pinion [26] mounted on a shaft [27] which is supported by bearings [28,3 0] and bearing fixings [29,3 1]. Rotation of the crown wheels results in rotation of the output shafts [8,9] and suspension units [ 16,17] as previously described.

Optionally, brakes (not shown) acting on the output shafts [8,9] or the outer casing [2 1] may be mounted on the inner gearbox supports [23], output shafts, and/or outer casing to hold the shafts when the levelling system is not in use and the vehicle is in motion, in order to relieve the crown wheels, pinion and pinion shaft of potential road shocks and vibration. The brakes may be of any suitable type, examples of which are disk brakes, externally contracting brakes (both acting on the output shafts), internally expanding brakes (acting on the outer casing) etc.

Front to back levelling is provided with the automatic raising and lowering of the modified front support wheel [3], a detailed view of which is given in Figures 5 and 6. The support wheel main cylindrical body [39] contains two inner cylindrical bodies [40,41] which are free to slide through each other, restricted at extremes via stops. Each cylindrical body has a corresponding inner threaded bar [42,43,44] which run inside each other and form a telescopic bar, driven by the motor [47] and gearbox [46]. The telescopic bar formed from the three threaded bars is supported by bearings at the top [3 8] and the bottom [451.

The telescopic bar can also be operated manually, via the handle [32]. In normal motorised use, the handle is in the position shown in the Figures, with the handle shaft [34] in its lower position, placing locking pin [35] in the locking shell [36], preventing the motor from driving the handle. To operate manually, the handle is flipped over, raising the shaft [34] due to the position of the handle pin [33], thereby raising the locking pin [35] free from the locking shell [36]. The lower end of the handle shaft [34] comprises a spline shaft [37] which slides vertically in the top of the outer thread [42]. The telescopic bar is then free to extend/contract by rotation of the handle. The gearing of the gearbox [46] provides a substantially greater turning friction than the thread contacts, ensuring the system functions correctly.

The chassis and levelling system is shown in operation from the front in Figure 7 and from the side in Figure 8.

The motors used in the system are operated by an automatic control system. The control system may be analogue based, a simplified block diagram of a suitable system being shown in Figure 9, or digitally based, as shown in Figure 10. The said examples are based on a symmetrical power supply, but can equally be designed for use with single rail supplies. The controller can also automatically operate motorised comer steadies (with sensors to detect ground contact) after the system has levelled the chassis. Comer steady circuitry is included as an example in the block diagram in Figure 10. The comer steady sensors in Figure 10 are motor current devices. Equally, contact sensors can be used.

Also shown in Figures 9 and 10 are manual switches for control of the front support wheel, in order to aid hitching and unhitching of the towing vehicle.

Additionally, the levelling system may include a separate locatable strut, which may be used in conjunction with the levelling system in order to aid in wheel changing. The electronic control system can incorporate additional manual controls for the axle motor in a similar fashion to the hitching/unhitching controls operating on the front support wheel motor, allowing the user the opportunity to raise one wheel from the ground.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

S

Claims (11)

1. A levelling system for a vehicle having first and second wheels supported by respective suspension units on the vehicle, the system comprising a drive unit mechanically linked and acting on the suspension units, such that, in use, the drive unit causes the first wheel to move upwardly, and the second wheel to move correspondingly downwardly, resulting in an angular rotation of the chassis in the side to side plane (roll).

2. A levelling system as claimed in Claim 1, wherein a modified motorised front support wheel provides raising and lowering of the front of the chassis, resulting in an angular rotation in the front to back plane (pitch).

3. A levelling system as claimed in Claim 1 or Claim 2, wherein an electronic device provides automatic control of the complete system.

4. A levelling system as claimed in Claim I and any preceding Claim, wherein the electronic control system also operates motorised comer steadies initiated either manually or automatically after the levelling process has been completed.

5. A levelling system as claimed in any preceding Claim, wherein two axles are used, and are mechanically or electronically linked to provide identical rotational levelling.

6. A levelling system as claimed in any preceding Claim, wherein front to back levelling is additionally or alternatively provided with the use of a second axle and suspension system, mechanically or electronically linked to the first suspension system, and acting in a similar manner to the side to side levelling system.

7. A levelling system as claimed in any preceding Claim, wherein the front to back system acts via manual control, providing raising and lowering of the tow hitch, in order to ease and assist in the task of hitching and unhitching the towed vehicle to a towing vehicle.

8. A levelling system, wherein front to back rotational levelling acts via manual control, providing raising and lowering of the tow hitch, in order to ease and assist in the task of hitching and unhitching the towed vehicle to a towing vehicle.

9. A levelling system as claimed in any preceding Claim, wherein the side to side system acts via manual control, such that, with the use of a locatable support strut, the system lifts one wheel from the ground in order to assist in wheel changing.

10. A levelling system as claimed in any preceding Claim, wherein the mechanically linked levelling system in the axle is utilised in a similar manner in motorised vehicles such as motor homes, and provides side to side levelling on each axle.

11. A levelling system for towed vehicles substantially as described herein with reference to Figures I -10 of the accompanying drawings.