WO2007020467A1

WO2007020467A1 - Trailer for a vehicle

Info

Publication number: WO2007020467A1
Application number: PCT/GB2006/003112
Authority: WO
Inventors: Jonathan Peter Frost
Original assignee: Jonathan Peter Frost
Priority date: 2005-08-18
Filing date: 2006-08-18
Publication date: 2007-02-22
Also published as: GB2443142B; GB2443142A; GB0516991D0; GB0803486D0

Abstract

The present invention relates to a trailer for a vehicle and a combination of a vehicle and trailer. In particular, vehicles that are small cars with a short wheelbase and a restricted amount of luggage space in the boot. Conventional trailers are difficult to manoeuvre and significantly increase the length of a car. The invention provides a vehicle (1) and trailer (2) combination wherein the vehicle has a pair of rear wheels (5) rotatable about a first horizontal axis and the trailer (2) has a pair of wheels (6) rotatable about a second horizontal axis, the trailer being coupled to the vehicle in such a way that relative pivoting movement about a vertical axis is prevented.

Description

TRAILER FOR A VEHICLE

This invention relates to a trailer for a vehicle and to the combination of a vehicle and trailer. The invention relates particularly, but not exclusively, to the case where the vehicle is a car.

It has become relatively common to design small cars with their rear wheels close to the rear extremity of the vehicle. Such cars often have very limited luggage space. Trailers have been available for a wide variety of vehicles including small cars. A trailer for a small car typically has one pair of wheels and the front end of the trailer is spaced from the rear of the car to allow pivoting of the trailer relative to the car about a vertical axis. Such trailers have certain disadvantages; those include the fact that the overall length of the vehicle and trailer combination is significantly increased making the combination harder to manoeuvre, and the fact that reversing the vehicle and trailer combination is relatively difficult.

According to the invention there is provided a vehicle and trailer combination wherein the vehicle has a pair of rear wheels rotatable about a first horizontal axis and the trailer has a pair of wheels rotatable about a second horizontal axis, the trailer being coupled to the vehicle in such a way that relative pivoting movement about a vertical axis is prevented.

By providing a trailer in which pivoting movement about a vertical axis of the trailer relative to the vehicle is prevented, it becomes possible to provide a vehicle and trailer combination that is much easier to manoeuvre .

The wheels of the trailer are preferably close to the rear wheels of the vehicle and the spacing of the first and second horizontal axes is therefore preferably less than 2m and more preferably less than 1.5m. A small spacing of the first and second horizontal axes both leads to a reduced overall length of the vehicle and trailer combination, and makes it more practical to have a connection between the vehicle and the trailer that does not allow pivoting movement about a vertical axis. The trailer is preferably itself relatively short so that the overall length of the vehicle and the trailer is not very much greater than the overall length of the vehicle. The trailer is especially suited to use with a small car and in such a case the overall length of car and trailer may be no more than the overall length of a medium sized car. More particularly, the invention is particularly well-suited to small cars which have rear wheels close to the rear extremity of the car. Where reference is made to relative pivoting movement about a vertical axis being "prevented", it will be appreciated that it is not an essential feature of the invention that there is absolutely no pivoting movement. Clearly there may be a small amount of such movement, for example as a result of tolerances in the coupling.

Typically, whereas a conventional coupling might allow pivoting movement of ninety degrees or more, the coupling of the present invention will typically prevent pivoting movement of more than ten degrees, and preferably more than five degrees in each direction; in embodiments of the invention described below the pivoting movement is restricted to less than one degree in each direction. Preferably the trailer has only a single pair of wheels . In most cases, the vehicle will have, in addition to the pair of rear wheels, a pair of front steerable wheels. In this case, the spacing of the rear wheels of the vehicle from the front wheels is preferably at least 2 times the spacing of the second horizontal axis from the first horizontal axis. With such an arrangement, the increase to wear of tyres and any tendency of the trailer to judder is significantly reduced. Preferably the spacing of the first and second horizontal axes is in the range of 2m to 0.5m. Preferably the spacing of the trailer wheels from one another is in the range of from 2.2m to 1.2m. Preferably the trailer is coupled to the vehicle in such a way that relative vertical movement of the first and second axes is allowed. Such relative movement may be provided by coupling the trailer to the vehicle in such a way that relative pivoting movement about a horizontal axis transverse to the first and second horizontal axes is permitted; preferably, however, the trailer is coupled to the vehicle in such a way that relative pivoting movement about a horizontal axis generally parallel to the first and second horizontal axes is not permitted, or is restricted to an angle of less than ten degrees, but relative vertical movement of the first and second axes is allowed. By allowing such relative vertical movement, the vehicle and trailer combination is much better able to accommodate changes in relative heights of the surfaces engaged by the wheels of the vehicle and trailer combination.

Preferably, the trailer is connected to the vehicle via a connecting arm. Preferably the connecting arm is connected to the rear of the vehicle at a position offset laterally from the position at which the connecting arm is connected to the trailer. The lateral offset is preferably less than 500mm and more preferably less than 200mm. A lateral offset of this kind enables an especially advantageous method of accommodating relative vertical movement of the vehicle and trailer to be provided. The connecting arm may be connected to the rear of the vehicle at a position offset from the centre of the rear of the vehicle and may be connected to the trailer at a position in the centre, widthwise, of the trailer.

Preferably the connecting arm is resilient. Preferably the connecting arm is resilient in a horizontal direction transverse to the first and second horizontal axes for accommodating relative horizontal movement of the trailer towards and away from the vehicle. Such resilience may be useful in limiting the loads transferred through the coupling, for example, during breaking. The connecting arm may also be resilient in other directions, for example a vertical direction.

The connecting arm may take various forms . For example it may be straight or it may include at least one curved section. In one embodiment described below the arm is in the shape of a coil of about one and a half turns. The coil may be in the shape of a helix in the sense that one end of the coil is displaced along the axis of the coil from the other end, and/or it may be in the shape of a spiral in the sense that the radius of curvature of the arm gradually increases from one end of the coil to the other. The amount of trailer movement relative to the vehicle due to the resilience of the connecting arm should be limited. Preferably the amount of said movement is less than 100mm and preferably less than 30mm.

Preferably the total relative vertical movement allowable between the trailer and the vehicle is less than 500mm (corresponding to 250mm in each direction) . The amount of movement is preferably sufficient to allow kerbs or standard road calming measures such as sleeping policemen, to be easily traversed. The wheels of the trailer may also have their own vertical suspension arrangements. In some trailers wheels are rotatable (swivelable) about vertical axes for steering purposes, but it is preferred that the wheel of each trailer is not rotatable about a vertical axis. Preferably each wheel of the trailer rotates about a fixed axis, which is preferably a common axis for all the trailer wheels.

Preferably the coupling between the vehicle and the trailer restricts to some degree relative rotation of the trailer and vehicle at least to prevent the trailer turning over.

It is possible for there to be two or more laterally spaced couplings between the vehicle and the trailer, but O

preferably there is only one coupling between the vehicle and the trailer.

In order to maintain the overall style of the vehicle it is advantageous that the style of the rear of the trailer matches the style of the rear of the vehicle. Preferably the shape of a rear portion, preferably the whole of the rear end, of the trailer approximately corresponds to the shape of a rear portion , or the whole of the rear end, of the vehicle. Whilst the invention as described above is directed to the combination of a vehicle and trailer when connected together, the invention is also directed to such a combination when they are not connected together. Thus the invention provides a vehicle and trailer which are connectable to form a vehicle and trailer combination as defined above.

The present invention also provides a trailer suitable for use in a vehicle and trailer combination as defined above. The trailer may incorporate any of the features of the trailer of the combination defined above.

By way of example, an embodiment of the invention will now be described with references to the accompanying schematic drawings, of which:

Fig. 1 is an underneath plan view of a vehicle and trailer combination;

Fig. 2 is a side view of the combination; Fig. 3 is a side view of the invention illustrating a feature of the coupling between the vehicle and the trailer; Fig. 4 is a rear-end view of the trailer of the combination;

Fig. 5 is a series of side views of the combination showing relative vertical movement of the vehicle and trailer; Fig 6 is a series of end views of the combination showing relative rotation of the vehicle and trailer;

Fig. 7 is a plan view showing one particular form of connecting arm between the vehicle and trailer;

Fig. 8 is an end view of another particular form of connecting arm; and

Fig 9 is an end view of yet another particular form of connecting arm.

Referring first to first Figs. 1 and 2, there is shown a vehicle 1 and a trailer 2 connected together by a towing bar T. The vehicle has a pair of steerable front wheels 4 and a pair of rear wheels 5. The trailer has a single pair of wheels 6.

The vehicle 1 is not shown in any particular style but is typically a small car of the kind which has its rear wheels close to the rear extremity of the vehicle. An example of such a car is a Ford Ka (RTM) or a BMW MINI (RTM) .

The coupling of the trailer 2 to the rear of the vehicle 1 allows vertical movement of the trailer 2 relative to the vehicle 1 as indicated in Fig. 3 by arrow A5. By allowing that vertical movement the ability of the vehicle and trailer combination to accommodate, for example, varying gradients along a road is enhanced as shown in figure 5. The coupling of the trailer 2 to the vehicle 1 may take a variety of forms. As shown schematically in Fig. 3, the coupling may allow pivoting movement of the trailer 2 about a horizontal axis parallel to the axes of the wheels 5 and 6. In that case vertical movement of the trailer 2 relative to the vehicle 1 can be accommodated by the pivoting movement just referred to. Such pivoting movement is in certain applications undesirable since it may cause contact between the trailer

2 and the rear of the vehicle 1. Fig. 4 illustrates another form of coupling employing a connecting arm 7. The connecting arm is connected to the trailer at a pivot point

3 centred widthwise on the trailer but is connected to the rear of the vehicle at a pivot point 8 offset laterally from the centre. At the connections coupling allows pivoting movement about horizontal axes Xl and X2 which are perpendicular to the axes of the wheels 5 and 6, as indicated by arrows A2 and A4 in Fig. 4. By allowing those pivoting movements the trailer is able to move vertically relative to the vehicle, and also to tilt sideways relative to the vehicle, for example, to accommodate different sideways gradients experienced at any moment by the vehicle and the trailer as shown in figure 6. Also each of the trailer wheels 6 has its own suspension system allowing vertical movement of each wheel as indicated by arrows A3 I Fig. 4.

The coupling of the connecting arm 7 to the trailer 2 is, in accordance with the invention, such that pivoting movement of the trailer 2 relative to the vehicle 1 about a vertical axis is prevented. This special feature allows the front of the trailer 2 to be very close to the rear of the vehicle, even at the lateral extremities of the trailer 2, as can be seen for example in Fig. 1. Also the axes of the wheels 5 and 6 can be brought very close together which in turn makes it practical to have a coupling between the vehicle and the trailer that does not allow relative pivoting movement about a vertical axis.

The trailer 2 is shown in the drawings as extending upwardly to a height below the rear window of the vehicle 1, that being the preferred arrangement, but it will be understood that other arrangements are possible.

Figure 7 shows another possible form of connecting arm, whereby the connecting arm 7 is of an "S" shape as shown. Distance F represents the horizontal offset between the car connecting point and the trailer connecting point. The connecting arm 7 is resilient in the direction shown by the arrow G and is pivotally connected at pivot points 3 and 8.

Figures 8 and 9 show other possible forms of the connecting arm 7 attached to the pivot points 3 and 8. In figure 8 the bar is curved as shown and resilient in the same direction as indicated on figure 7. Figure 9 shows the connecting arm 7 in the shape of a coil spring, resilient in the same direction as in the other figures. In this case it may also be desirable for the arm to be resilient in the coiling/uncoiling direction: in that case it may even be possible for the connection of the arm 7 to the vehicle 2 to be a fixed connection not allowing any pivotal movement .

In one particular example of the invention, certain dimensions are as follows:

Spacing A of the outer faces of the trailer wheels 6 from one another: 1.7m.

Spacing B of the axis of the trailer wheels β from the axis of the vehicle rear wheels 5: 0.5m.

Spacing C of the axis of the vehicle rear wheels 5 from the axis of the vehicle front wheels 4: 2.5m.

Claims

1. A vehicle and trailer combination wherein the vehicle has a pair of rear wheels rotatable about a first horizontal axis and the trailer has a pair of wheels rotatable about a second horizontal axis, the trailer being coupled to the vehicle in such a way that relative pivoting movement about a vertical axis is prevented.

2. A vehicle combination according to claim 1, in which the spacing of the first and second horizontal axes is less than 2m.

3. A vehicle combination according to claims 1 and 2, in which the vehicle has a pair of front steerable wheels and the spacing of the rear wheels of the vehicle from the front wheels is at least 2 times the spacing of the second horizontal axis from the first horizontal axis.

4. A vehicle combination according to any preceding claim, in which the spacing of the first and second horizontal axes is in the range of 2m to 0.5m.

5. A vehicle combination according to any preceding claim, in which the spacing of the trailer wheels from one other is in the range of from 2.2m to 1.2m.

6. A vehicle combination according to any preceding claim, in which the trailer is coupled to the vehicle in such a way that relative pivoting movement about a horizontal axis transverse to the first and second horizontal axes is permitted.

7. A vehicle combination according to any preceding claim, in which the trailer is coupled to the vehicle in such a way that relative pivoting movement about a horizontal axis generally parallel to the first and second horizontal axis is not permitted.

8. A vehicle combination according to any preceding claim, in which the trailer is coupled to the vehicle in such a way that relative vertical movement between the trailer and vehicle is permitted.

9. A vehicle combination according to any preceding claim, in which the trailer is connected to the vehicle via a connecting arm.

10. A vehicle combination according to claim 9, in which the connecting arm is connected to the rear of the vehicle at a position offset from the centre of the rear of the vehicle.

11. A vehicle combination according to claim 9 or 10, in which the connecting arm is connected to the trailer at a position in the centre widthwise of the trailer.

12. A vehicle combination according to any of claims 10 to 11, in which the connecting arm is resilient.

13. A vehicle combination according to claim 12, in which the connecting arm is resilient in a horizontal direction transverse to the first and second axes for accommodating relative horizontal movement of the trailer and the vehicle.

14. A vehicle combination according to claim 12 or 13, in which the connecting arm includes at least one curved section.

15. A vehicle combination according to claim 12 or 13, in which the connecting arm is in the shape of a helical and/or spiral coil having at least one turn.

16. A vehicle combination according to any of claims 12 to 15, in which the amount of trailer movement in use due to the resilience of the connecting arm is less than 100mm.

17. A vehicle combination according to any of claims 12 to 15, in which the amount of trailer movement in use due to the resilience of the connecting arm is less than 30mm.

18. A vehicle combination according to any of claims 10 to 17, in which the connecting arm is connected to the rear of the vehicle at a position offset laterally from the position at which the connecting arm is connected to the trailer.

19. A vehicle combination according to claim 18, in which the lateral offset is less than 500mm.

20. A vehicle combination according to claim 19, in which the lateral offset is less than 200mm.

21. A vehicle combination according to claim 8, wherein the relative vertical movement allowable between the trailer and the vehicle is less than 250mm.

22. A vehicle combination according to any preceding claim, wherein the wheels of the trailer have their own vertical suspension arrangements.

23. A vehicle combination according to any preceding claim, in which there is only one coupling between the vehicle and the trailer.

24. A vehicle combination according to any preceding claim, in which the style of the rear of the trailer matches the style of the rear of the vehicle.

25. A vehicle and trailer combination substantially as herein described with reference to and as illustrated by the accompanying drawings .

26. A vehicle and trailer which are connectable to form a vehicle and trailer combination as defined above.

27. A trailer suitable for use in a vehicle and trailer combination according to any of claims 1 to 25.