WO2023068927A1

WO2023068927A1 - Device for steering steerable wheels of a trailer, and trailer comprising such a steering device

Info

Publication number: WO2023068927A1
Application number: PCT/NL2022/050592
Authority: WO
Inventors: Gerrit KOOIJ
Original assignee: Koninklijke Nooteboom Group B.V.
Priority date: 2021-10-19
Filing date: 2022-10-19
Publication date: 2023-04-27
Also published as: EP4419412A1; NL2029467B1

Abstract

The invention relates to a device for steering a number of steerable wheels of a trailer which are placed on different, mutually parallel axle lines. The steering device comprises a transmission member which extends in longitudinal direction of the trailer and to which each of the steerable wheels is connectable by a steering rod. This transmission member is pivotable in a plane parallel to the axle lines. The invention also relates to a trailer, provided with a number of mutually parallel axle lines with steerable wheels and such a steering device.

Description

DEVICE FOR STEERING STEERABLE WHEELS OF A TRAILER, AND TRAILER COMPRISING SUCH A STEERING DEVICE

The invention relates to a device for steering a number of steerable wheels of a trailer which are placed on different, mutually parallel axle lines, comprising at least one transmission member which extends in longitudinal direction of the trailer and to which each of the steerable wheels is connectable by a steering rod. Such a steering device is known in different variants.

A conventional steering device has a transmission member which extends in longitudinal direction of the trailer. At each axle line, this transmission member is connected to a leg of a steering bracket, which is mounted pivotally in the trailer. The other leg of the steering bracket is connected to two steering rods which each extend toward a side of the trailer and which are each connected to a steering arm of one of the steerable wheels. The transmission member is mounted in the trailer for movement in longitudinal direction and is connected at an end to an actuator, which moves the transmission member forward or rearward. The actuator receives a steering signal on the basis of a steering movement of a pulling vehicle connected to the trailer.

The known steering device has the drawback that it has a relatively large number of pivot bearings, whereby the construction of the steering device is relatively complex and costly, and requires regular maintenance.

The invention has for its object to provide a steering device of the above described type, which has a simpler construction. This is achieved according to the invention in that the at least one transmission member is pivotable in a plane substantially parallel to the axle lines. Giving the transmission member a pivotable form enables the steering rods of the steerable wheels to be connected directly to the transmission member and makes it possible to dispense with the use of steering brackets at each axle line, whereby considerably fewer pivot bearings are required.

In an embodiment of the steering device the at least one transmission member can be configured to be mounted pivotally in a chassis of the trailer at or close to an outer end. By having the pivoting movement take place around one of its outer ends the transmission member has a different movement at each axle line.

The at least one transmission member can further be configured to be mounted slidably in the chassis at a distance from the pivotable bearing. By mounting the transmission member at a different point as well the pivot bearing is less heavily loaded and can be constructed in simple manner and at lower cost. Bending of the transmission member is additionally reduced in this way.

In a further embodiment the steering device can be provided with means for pivotally driving the at least one transmission member The wheels can thus be actively steered. The drive means can here thus engage on the at least one transmission member at a distance from the pivotable bearing. A great moment arm is thus created, whereby the drive means need generate relatively low steering forces.

In an embodiment of the steering device the drive means can comprise actuators to be connected to the chassis and arranged on either side of the transmission member. Controlling the transmission member from two sides achieves a stable and reliable steering.

The drive means can be configured here to receive a steering signal on the basis of a steering movement of a pulling vehicle connected to the trailer. The steering movement of the steerable wheels of the trailer is thus brought into line with that of the pulling vehicle so as to be able to thus realize the Ackermann principle and reduce tyre wear. When the actuators comprise hydraulic piston/cylinder combinations, these can for instance be directly hydraulically connected to hydraulic piston/cylinder combinations at the position of the coupling of the trailer to the pulling vehicle, which are controlled when the pulling vehicle negotiates a bend.

In an embodiment of the steering device the transmission member can extend along a central axis of the trailer and the steering rods of each axle line can have the same length. In this way the movement of the transmission member directly determines the steering deflection of the steerable wheels of each axle line. The steering angles of the steerable wheels of the different axle lines then relate to each other as the distances of the different axle lines to the pivot point of the transmission member.

The steering device can further be provided with means for bounding a pivoting movement of the transmission member. These bounding means can for instance take the form of stops mounted in the chassis, but can also be incorporated in the actuators. When hydraulic piston/cylinder combinations are used as actuators, the pivoting movement can be bounded in simple manner by the maximum inward or outward stroke.

In an embodiment of the steering device the at least one transmission member can be stiffer in the plane of its pivoting movement than in a direction transversely of that plane. This prevents the steering movements of the steerable wheels from being influenced by possible deformation of the transmission member during the pivoting movement.

This can be achieved in relatively simple manner when the at least one transmission member has a flat cross-section. A flat cross-section has in a main direction a considerably greater stiffness than in a direction transversely thereto.

The invention also relates to a trailer which is provided with a number of mutually parallel axle lines with steerable wheels and with a steering device as described above.

In an embodiment the trailer can further be provided with a chassis on which components of the steering device are mounted. In another embodiment the transmission member of the steering device can be pivotally mounted in the chassis in front of a front axle line, as seen in the direction of travel. When it is mounted in front of the front axle line, the wheels of the front axle line can also be steered when the transmission member performs a pivoting movement. In this setup all wheels will be steered in the same direction. On the other hand, it is possible to envisage that the pivotable mounting of the transmission member in the chassis lies between two axle lines. In that case the wheels of the axle lines in front of and behind the rotation point of the transmission member will be steered in opposite directions. If the rotation point were to coincide with one of the axle lines, the wheels of this axle line would have no steering deflection in the event of a pivoting movement of the transmission member about its rotation point.

When in a trailer of the above described type the steerable wheels on either side of the trailer are in each case connected by an axle body, the transmission member of the steering device can be pivotable in a space between the axle bodies and the chassis. A compact steering device is obtained hereby.

In an embodiment of the trailer the transmission member of the steering device can be slidably mounted in the chassis close to a rear axle line, as seen in the direction of travel. As stated, such an additional mounting results in a reduction of loads on the pivot bearing and decreased bending of the transmission member.

Finally, a trailer as described above can be provided with means for pivotally driving the at least one transmission member, which drive means can comprise actuators connected to the chassis and placed close to a rear axle line, as seen in the direction of travel, on either side of the transmission member.

The invention is now elucidated on the basis of an embodiment, wherein reference is made to the accompanying drawing, in which:

Fig. 1 is a perspective bottom view of a rear part of a trailer which is provided with a steering device according to the invention, wherein the wheels are shown in a straight position;

Fig. 2 is a perspective top view of the trailer part with the steering device of Fig. 1, wherein the chassis and the loading surface have been omitted for the sake of clarity;

Fig. 3 is a bottom view of the trailer part with a steering device of Fig. 1, wherein the wheels are shown in a steered position; and

Fig. 4 is a perspective bottom view on enlarged scale of the circled detail IV in Fig. 3, but with the wheels once again in the straight position.

A trailer 1 is provided with a chassis 2, which in the shown embodiment is formed by a central beam 3 and a number of trusses 4. Only a rear part of trailer 1 is otherwise shown here, this extending further forward - as seen in the direction of travel D - and there having for instance a gooseneck for coupling to a pulling vehicle (not shown). Wheel carriers 5, to each of which an end of a leaf spring 6 is attached, protrude here from the underside of the chassis. The other end of each leaf spring 6 is attached to a pneumatic spring unit 7, which is likewise mounted on the underside of chassis 2. The wheel carriers 5 here take the form of tubes manufactured from a similar material as the rest of chassis 2.

Each pair of leaf springs 6 on either side of trailer 1 in each case supports an axle body 8 which is further connected via two shock absorbers 9 to chassis 2. Each axle body 8 defines an axle line A, in the shown embodiment a total of four axle lines A1-A4, which are mutually parallel and in the shown embodiment all have the same intermediate distance. Situated at each end of the axle body 8 is a swivel pin 10 on which a swivel axle 11 is pivotally mounted. Each swivel axle 11 carries a wheel 12, this taking a double form in the shown embodiment. The wheels 12 are each rotatable around the axle line A. Each swivel axle 11 further has a steering arm 13 which is connected to a steering device 14 to be discussed below. In the shown embodiment the steering arms 13 extend forward, as seen in the direction of travel D of trailer 1.

In the shown embodiment the steering device 14 according to the invention comprises a transmission member 15 which extends in the longitudinal direction L of trailer 1. At an end 16 the transmission member 15 is pivotally mounted in chassis 2 at a position lying in front of the front axle line Al, as seen in the direction of travel D. In the shown embodiment the transmission member 15 has a bush 17 which is mounted round a shaft stub 18 protruding from chassis 2, although other bearings can also be envisaged. In this embodiment the transmission member 15 extends to a position just before the rear axle line A4. Transmission member 15 is also slidably mounted close to a rear end 19. For this purpose a bearing plate 20 is mounted between the pneumatic spring units 7 of the rearmost-but-one axle line A3 of chassis 2. A thinned segment 21 of transmission member 15 rests on this bearing plate 20 and slides thereover when transmission member 15 performs a pivoting movement.

Transmission member 15 is provided at each axle line A with mounting points 22 for mounting inner ends 23 of two steering rods 24. The steering rods 24 are each connected with their outer ends 25 to the steering arm 13 of the corresponding steerable wheel 12. In the shown embodiment the mounting points 22 are situated on the underside of transmission member 15, and here comprise vertically directed ears.

In the shown embodiment the steering rods 24 extend substantially transversely of the longitudinal axis L of trailer 1. Steering rods 24 can all have the same length, whereby the steering deflection of the steerable wheels 12 of each axle line A is proportional to the movement of the transmission member 15, as shown here. This makes it possible to realize a first approximation of the Ackermann principle in simple manner. On the other hand, it is also possible to envisage opting for different lengths of steering rods 24 of the successive axle lines A, such that the Ackermann principle is approximated as closely as possible over a wide range of steering angles. Finally, for an optimal approximation steering rods 24 which are length-adjustable during travel, as described in the earlier patent application NL 2028833, could be opted for.

The steering device 14 further comprises drive means 26 for the purpose of having transmission member 15 perform a pivoting movement. In the shown embodiment the drive means are formed by two actuators 27 which act on transmission member 15 on both sides. Each actuator 27 has an inner end 28 which is connected to transmission member 15 and an outer end 29 which is connected to chassis 2. In the shown embodiment the actuators 27 are hydraulic piston/cylinder combinations, but other types of drive means, such as for instance electromechanical drives, can also be envisaged. In the shown embodiment actuators 27 engage on a part of transmission member 15 which is removed relatively far from the pivotally mounted end 16 and is situated close to the rear end 19. A relatively large moment around the pivot axis can thus be generated with relatively small actuators.

The drive means 26 can be controlled on the basis of a steering signal. This steering signal can be derived from a steering movement of a pulling vehicle to which trailer 1 is coupled. In the case of hydraulic actuators the steering signal can be generated in simple manner by incorporating the actuators 27 in a hydraulic circuit (not shown) in which one or more hydraulic signal generators are also incorporated. A piston/cylinder combination, an end of which is connected to the pulling vehicle and the other end to the trailer, can function as hydraulic signal generator. In such a setup a steering movement of the pulling vehicle results relative to the trailer in an inward or outward stroke of the hydraulic signal generator, whereby hydraulic liquid is pressed through the circuit and the hydraulic actuators 27 also perform an inward or outward stroke, which is converted into a pivoting movement of transmission member 15.

In order to minimize the deformation the transmission member 15 is in the shown embodiment stiffer in the plane of its pivoting movement than in a direction transversely of that plane. As is visible, this is achieved in that transmission member 15 takes the form of a beam with a flat cross-section, the width of which is greater than the height. The cross-section is otherwise not constant over the whole length of transmission member 15. There is for instance a narrowed segment 30 at the position of the pneumatic spring units 7 of the second axle line A2, while several weight reduction holes 31 are additionally formed distributed over the length of transmission member 15. Transmission member 15 is further provided at the position of each of the front three axle lines A1-A3 with a recess 32 to create space for the associated axle body 8, while, as stated, a segment 21 is thinned close to rear end 19 at the position of the bearing plate 20. Owing to the flat cross-section, transmission member 15 otherwise fits well into a space between the upper side of axle bodies 8 and the underside of chassis 2.

In order to prevent transmission member 15 from inadvertently coming into contact with surrounding parts of trailer 1, steering device 14 is also provided with means for bounding the pivoting movement of transmission member 15. In the shown embodiment these bounding means are formed by co-acting end surfaces in the piston/cylinder combinations 27 which bound the inward or outward stroke of these actuators. It is however also possible to envisage use being made of stops which are attached to chassis 2 and with which transmission member 15 can make contact. The steering device shown and described here enables the steerable wheels of a number of axle lines to be controlled centrally without a steering bracket being necessary at each axle line. It is possible here to suffice with a relatively simple construction which can be manufactured at lower cost, is more robust and requires less maintenance than conventional steering devices for axial pivot steering. Although the invention has been elucidated above on the basis of a number of examples, it will be apparent that it can be varied in many ways within the scope of the following claims.

Claims

7 Claims

1. Device for steering a number of steerable wheels of a trailer which are placed on different, mutually parallel axle lines, comprising at least one transmission member which extends in longitudinal direction of the trailer and to which each of the steerable wheels is connectable by a steering rod, wherein the at least one transmission member is pivotable in a plane substantially parallel to the axle lines.

2. Steering device according to claim 1, wherein the at least one transmission member is configured to be mounted pivotally in a chassis of the trailer at or close to an outer end.

3. Steering device according to claim 2, wherein the at least one transmission member is configured to be mounted slidably in the chassis at a distance from the pivotable bearing.

4. Steering device according to any one of the foregoing claims, further provided with means for pivotally driving the at least one transmission member.

5. Steering device according to claim 2 or 3 and claim 4, wherein the drive means engage on the at least one transmission member at a distance from the pivotable bearing.

6. Steering device according to claim 4 or 5, wherein the drive means comprise actuators to be connected to the chassis and arranged on either side of the transmission member.

7. Steering device according to any one of the claims 4-6, wherein the drive means are configured to receive a steering signal on the basis of a steering movement of a pulling vehicle connected to the trailer.

8. Steering device according to any one of the foregoing claims, wherein the transmission member extends along a central axis of the trailer and the steering rods of each axle line have the same length.

9. Steering device according to any one of the foregoing claims, further provided with means for bounding a pivoting movement of the transmission member. 8

10. Steering device according to any one of the foregoing claims, wherein the at least one transmission member is stiffer in the plane of its pivoting movement than in a direction transversely of that plane.

11. Steering device according to claim 10, wherein the at least one transmission member has a flat cross-section.

12. Trailer, provided with a number of mutually parallel axle lines with steerable wheels and a steering device according to any one of the foregoing claims.

13. Trailer according to claim 12, further provided with a chassis on which components of the steering device are mounted.

14. Trailer according to claim 13, wherein the transmission member of the steering device is pivotally mounted in the chassis in front of a front axle line, as seen in the direction of travel.

15. Trailer according to any one of the claims 12-14, wherein the steerable wheels on either side of the trailer are in each case connected by an axle body, and the transmission member of the steering device is pivotable in a space between the axle bodies and the chassis.

16. Trailer according to claim 14 or 15, wherein the transmission member of the steering device is slidably mounted in the chassis close to a rear axle line, as seen in the direction of travel.

17. Trailer according to any one of the claims 12-16, wherein means for pivotally driving the at least one transmission member comprise actuators connected to the chassis and placed close to a rear axle line, as seen in the direction of travel, on either side of the transmission member.