A BEAM FOR A HEAVY VEHICLE

TECHNICAL FIELD

The invention relates to a beam for a heavy vehicle according to the preamble of claim 1.

The invention is applicable on heavy vehicles, in particular trucks. The invention is, however, not restricted to trucks, but may also be used for example in wheel loaders, articulated haulers, excavators and buses.

BACKGROUND OF THE INVENTION

In a heavy vehicle having a towing member for connection to a towed trailer, the towing member is arranged to distribute the load from a towed trailer to the frame of the heavy vehicle. It is important that the load does not result in stress concentrations in the frame so as to ensure that the chassis is able to withstand the load and to avoid crack propagation.

A towing member which is constituted by an end cross member arranged in the rear part of the towing vehicle is usually shaped as a U-beam which is attached to the longitudinal main beams of the chassis frame. In addition to the portions of the end cross member which form the U-shape, the beam has also lateral flanges which are to be connected to the longitudinal main beams by means of any suitable fastener means, such as bolts, screws, rivets or similar. It has been found out that the corners of the end cross member formed between the flanges can be weak points due to stress concentrations in despite of the fact that the flanges are bolted to the frame in one or more positions.

According to prior art it is possible to weld the lateral flanges together in order to unload the corners of the end cross member. Such welding will however result in increased manufacturing costs, and a further drawback is the difficulty to calculate and design an end cross member with welded flanges with respect to fatigue stresses.

Another possible already known solution for reinforcement of the end cross member is to use additional plates for connecting the flanges of the end cross beam. Such a multi sheet

design will however result in increased manufacturing costs, and increased weight of the component.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a beam for a heavy vehicle of the kind mentioned in the introduction herein, and particularly an end cross beam constituting a towing member of a truck, by which beam the problem of stress concentration can be reduced to a substantial extent in a cost effective way.

The object is achieved by a beam for a heavy vehicle according to claim 1.

By the provision of a beam where at least a part of the periphery portion of the first portion flange and at least a part of the periphery portion of the second portion flange are connected to each other by means of a connecting member acting on both the first portion flange and the second portion flange so as to enable load to be transferred between the first portion flange and the second portion flange via the connecting member and counteract movement of the first portion flange and the second portion flange relative to each other, a "closed" corner can be achieved, and the strength of the beam can be increased. The term "connecting member" is meant to comprise any suitable means for connecting the flanges relative to each other either by engagement of the flanges or by clamping the flanges against a further component, such as the frame, of a heavy vehicle in order to counteract movement of said flanges relative to each other. It is also possible to combine the both main aspects of the invention, i.e. engagement and clamping. The term "connecting member" is not mentioned to comprise a weld joint or any similar means making it impossible to separate the flanges without breaking the material. The definition of the connecting member is further discussed in the detailed description herein.

The invention is based on the insight that a so called closed corner gives a favourable load distribution and less stress concentrations which counteracts crack propagation in the corner. The periphery portions of the first portion flange and the second portion flange can be connected to each other and movement of the periphery portions relative to each other can be counteracted by means of one and the same connecting member. For example one single screw or bolt can be used for connecting the both flanges to each other.

According to one embodiment of the invention, the connecting member is formed by means of the shape of the first portion flange and the second portion flange, and engagement between the first portion flange and the second portion flange. The connecting member is preferably formed by a protruding portion in one of the first portion flange and the second portion flange, and a recess for receiving the protruding portion which recess is arranged in the other of the first portion flange and the second portion flange. In this embodiment the flanges are connected and substantially locked relative to each other without using any external fastener means. This embodiment of the invention results in a very reliable design without adding any weight to the beam and the vehicle. The invention also relates to a heavy vehicle provided with such a beam as described herein.

According to another embodiment of the invention, the first portion flange and the second portion flange are designed and arranged relative to each other so as to receive said locking member between the first portion flange and the second portion flange, and the connecting member is arranged to clamp both the first portion flange and the second portion flange against a further component of the heavy vehicle, and preferably the first portion flange is provided with a first recess and the second portion flange is provided with a second recess, wherein the first portion flange and the second portion flange are arranged in such a way that the first recess and second recess together constitute a through hole for receiving said connecting member therein. By clamping the periphery portions of the flanges against the further component by means of a bolt or screw any relative movement of the flanges can be counteracted, and at the same time a standard component can be used as the connecting member. The invention also relates to a heavy vehicle provided with such a beam clamped to the frame of the vehicle in the way as described herein.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

In the drawings:

Fig. 1 is a perspective view of a heavy vehicle provided with a beam according to the invention,

Fig. 2 is a perspective view of a beam according to the invention,

Fig. 3 is a lateral view of a portion of a heavy vehicle end cross member according to prior art,

Fig. 4a and 4b are schematic illustrations of the invention where the flanges are connected to each other by means of a connecting member formed in the flanges,

Figs. 5a, 5b and 5c are schematic illustrations of different embodiments of the invention where the flanges are to be clamped to a frame by means of a locking member, and

Figs. 6a and 6b are schematic illustrations of prior art and the principle of the invention, respectively.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Figure 1 is a perspective view of a heavy vehicle 1 provided with a beam 2 according to the invention. The heavy vehicle is a truck and the beam is an end cross member for towing a trailer. The end cross member which is formed as a U-beam can have apertures 3 (see also Fig. 2) and/or any other means for mounting a coupling device (not illustrated) to the end cross member. The coupling device is used for enable connection to a trailer to be towed by the truck. The end cross member is arranged between and attached to two longitudinal main beams of the frame 9 of the truck in the rear part of the truck 1.

As appears from Fig. 2, the beam 2 comprises a first portion 4 and a second portion 5 which are connected to each other and angled relative to each other so as to form a corner 6. At a first end 60 of the beam, the first portion 4 has a flange 7 extending downwardly in a geometric plane, and the second portion 5 has a flange 8 extending forwardly and arranged substantially in the same geometric plane. The first and second portion flanges are directed towards each other or in directions towards the longitudinal

centre line 70 of the beam 2, and the flanges 7, 8 are used for mounting the end cross member 2 to the chassis frame 9. In the embodiment illustrated the beam 2 also comprises a third portion 10 connected to the second portion 5. The second portion 5 and the third portion 10 are angled relative to each other. The first, second and third portions preferably form a U-beam. The third portion 10 may have a third portion flange 11 arranged substantially in the same plane as the first portion flange 7 which third portion flange 11 extends upwardly. The extension directions downwardly, forwardly and upwardly are firstly used to describe the flanges directions relative to each other, although these directions can be used for indicate how the beam and the flanges are preferably orientated when the beam is installed in the truck.

The first portion 4 is preferably a sheet and the first portion flange 7 is bended from the sheet to form an angle α between the first portion flange 7 and the remaining part 4 of the first portion. The angle α is preferably substantially 90°. The second portion 5 is preferably a sheet and the second portion flange 8 is bended from the sheet to form an angle β between the second portion flange 8 and the remaining part 5 of the second portion. The angle β is preferably substantially 90°. The first portion 4 and the second portion 5, as well as the second portion 5 and the third portion 10, form an angle θ which is preferably substantially 90°.

Furthermore, at the second end 61 of the beam 2 corresponding flanges 7b, 8b, and 11b are preferably arranged in the same way to enable also this end 61 of the end cross member 2 to be attached to the chassis frame 9.

In Fig. 3 a portion of an end cross member 50 according to prior art is illustrated in a lateral view. Although the lateral flanges 51 of the end cross member 50 are attached to the chassis of the vehicle by means of several bolts, stress concentrations can arise in the corners 52. Undesired movements in the unlocked material in the periphery portions 53 of the flanges closest to the corner due to the load transferred during towing of a trailer will cause stresses in the corner 52 of the end cross member 50.

With reference to Figs. 6a and 6b, the principle of the invention is further explained and compared to the design used in the prior art heavy vehicle beam illustrated in Fig. 3. Fig.

6a shows in a cross section view how the load is transferred between two adjacent flanges 71 which are conventionally bolted to a further component 72 (see also Fig. 3).

The load is transferred from one flange to said further component and then to the other flange. See dash dotted lines 73. This implies that any movement between the flanges is counteracted solely by said further component.

In contrary, by means of a connecting member 13b in accordance with the invention, which connecting member acts on both flanges 74, 75 as illustrated in Fig. 6b, load can also be transferred between the flanges via the connecting member, such as a bolt. This will result in an increased strength of the design. Due to the friction between the connecting member 13b and the flanges 74, 75 also the material of the connecting member, the bolt head in the illustrated example, counteracts any movement of the flanges relative to each other. See dash dotted lines 76 in Fig. 6b.

As illustrated for example in Fig. 4a, according to another aspect of the invention a periphery portion 12 of the first portion flange 7 and a periphery portion 12b of the second portion flange 8, which periphery portions 12, 12b are preferably arranged adjacent to each other and close to the corner 6, are connected to each other by means of a connecting member 13 shaped in the flanges. In this case the flanges are substantially locked against movement relative to each other by the connecting member 13 so as to improve the strength of said corner.

In the embodiments illustrated in Fig. 4a and 4b the connecting member 13 is formed by means of the shape of the first portion flange and the second portion flange. The connecting member can be formed by a protruding portion 14 in one of the first portion flange and the second portion flange (the second portion flange 8 in the illustrated example), and a corresponding portion having a recess 15 in the other of the first portion flange and the second portion flange (the first portion flange 7 in the illustrated example). The first portion flange 7 and the second portion flange 8 are connected to each other by engagement between said protruding portion 14 and the recess 15. The connecting member 13 is preferably designed as a puzzle piece-joint which implies that the flanges 7, 8 are locked to each other in all directions within the main extension plane of the flanges 7, 8. In this embodiment no external connecting member is needed. The strength of the corner can be improved by the fact that load can also be transferred directly between the flanges. In Fig. 4b each flange 7, 8 is provided with at least one of a protrusion in the shape of a square teeth and a corresponding square shaped recess, whereby the flanges

are connected to each other by engagement between the protrusion and the other flange receiving the protrusion in the recess.

In the different embodiments illustrated in Fig. 5a, 5b, and 5c the first portion flange 7 and the second portion flange 8 are arranged relative to each other so as to receive an external connecting member 13b between the first and second portion flanges, and enable the connecting member 13b to clamp the first and second portion flanges against a further component of the heavy vehicle 1. The further component is preferably the frame 9 of the heavy vehicle (See Fig. 19). The beam can be attached to the longitudinal main beams of the frame with or without intermediate spaces arranged between the cross member beam 2 and the frame 9. The first portion flange 7 and the second portion flange 8 are preferably arranged close to each other but separately from each other. In other words, the current flanges are arranged substantially in one and the same geometric plane and the flanges are not overlapping each other when looking at the lateral view of the beam 2, i.e. in a direction perpendicular to the main extension plane of the flanges 7, 8. Advantageously the flanges are arranged in the same geometric plane so as to make the installation easy and to eliminate the need of adaptations of the frame or the spacers used which otherwise are required.

In the embodiment illustrated in Fig. 5a the distance between the flanges is adapted to the connecting member 13b, a bolt, in a way such that the bolt can be arranged between the flanges and at the same time the bolt head is able to clamp both flanges against the frame of the heavy vehicle. In the embodiments illustrated in Fig. 5b and 5c, the first portion flange 7 is provided with a first recess 20 and the second portion flange 8 is provided with a second recess 21. The first portion flange 7 and the second portion flange 8 are further arranged in such a way that the first recess 20 and second recess 21 together constitute a through hole for receiving the connecting member 13b therein. This implies that the through hole can be of the same size as the other standard holes used for connection of the end cross beam and a corresponding standard screw or bolt can used as the locking means. The first recess 20 is preferably a part of a circular through hole and the second recess 21 is preferably substantially the remaining part of said circular through hole, and more preferably the first recess constitutes substantially 50% of said circular through hole.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize

that many changes and modifications may be made within the scope of the appended claims.