GB2454142A

GB2454142A - Driveshaft

Info

Publication number: GB2454142A
Application number: GB0902844A
Authority: GB
Inventors: Christoph F Rueegg
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-08-28
Filing date: 2007-08-21
Publication date: 2009-04-29
Anticipated expiration: 2027-08-21
Also published as: GB2454142B; GB0902844D0; WO2008025177A1; DE112007001768A5; DE112007001768B4

Abstract

A driveshaft, which absorbs collision energy, for motor vehicles is composed of a cylindrical hollow shaft (10) composed of fiber-reinforced plastic and a force introduction connection (20) composed of metal, which force introduction connection comprises a connection flange (22) and a cylindrical tube (21) whose free end is provided with an axially parallel peripheral toothing (13) and is pressed into that end of the hollow shaft (10) which is provided with an outer support (11). The peripheral toothing cuts into the inner wall of the hollow shaft and thereby connects the tube and the hollow shaft to one another in a rotationally fixed manner. The tube (21) projects out of the hollow shaft (10) by a length (S) and, in the event of a collision of the motor vehicle, is pushed axially into the hollow shaft by up to said length so as to partially absorb the collision energy. An additional reinforcement (30) is arranged on the hollow shaft (10) axially adjacent to the support (10), which additional reinforcement (30) extends in the axial direction substantially over a length which corresponds to the maximum movement travel of the tube (21) into the hollow shaft. By means of suitable dimensioning and distribution of the strength of said additional reinforcement (30), it is obtained that the resistance force which counteracts the movement of the tube does not fall below the desired value, for example 60 kN, over the entire movement travel. The driveshaft is characterized by a high energy absorption capacity and is at the same time relatively very simple and cost-effective to produce.

Description

Drive shaft [0001]The invention relates to a collision-energy-absorbing drive shaft for motor vehicles according to the preamble of the independent claim 1.

[0002] Drive shafts made of fibre-reinforced plastics material are being used more and more frequently in automotive engineering above all because of their significantly lower weight compared to conventional constructions made of metal.

On the other hand, it is more and more frequently demanded that the drive shafts also be included in safety considerations. In other words, in the event of a collision of the vehicle, the drive shaft should also be in a position to absorb part of the collision energy.

[0003] Energy-absorbing drive shafts are already known in different variants.

Typical representatives of such drive shafts are, for example, described in the documents EP 0 683 328 BI and WO 2004/097233. The energy is absorbed here by axial compression of the drive shaft with at least partial destruction of the fibre-reinforced plastics material shaft. These known drive shafts are all constructed in a relatively complicated manner and can accordingly only be produced with difficulty or at least with a relatively large outlay.

[0004]A collision-absorbing drive shaft of the generic type is described in the document DE 30 07 896 Al. This known drive shaft is structurally simple and can be produced without great outlay but its energy absorption properties are unsatisfactory in practice. In the event of a collision, at least one of the two force introduction connections is pushed axially into the fibre-reinforced plastics material shaft. In this case, a high resistance force is initially produced but this already practically disappears after a very short compression path because of the explosion of the fibre-reinforced shaft which then follows. The energy absorbing capacity of this drive shaft is therefore relatively low and unsatisfactory in practice.

[0005]Proceeding from this prior art, a drive shaft of the generic type is to be improved with regard to its energy absorption capacity by the present invention, with the drive shaft having to remain structurally simple at the same time, however, and be producible without great outlay.

[0006] The solution to this object on which the invention is based emerges from the features described in the characterising part of the independent claim 1. Particularly advantageous configurations and developments are the subject of the dependent claims [0007]The invention will be described in more detail below with the aid of the drawings, in which: [0008]Fig. 1 shows a partially axial section of an embodiment of the drive shaft according to the invention, [0009] Fig. 2 shows an axial section similar to Fig. 1 but in the compressed state, [O010]Fig. 3 to 4 each show an axial section through two further embodiments, [001 1]Fig. 5 shows a graph of the axial forces occurring during a compression of the drive shaft, for example caused by a collision and [0012]Fig. 6 to 8 each show an axial section through three further embodiments of the drive shaft according to the invention.

[0013]The drive shaft according to the invention shown comprises, as a central component, a hollow shaft 10 made of fibre-reinforced plastics material and two force introduction connections 20 made of metal, which are connected in a rotational])' fixed manner to the two ends of the hollow shaft 10 and are used for coupling or uncoupling the torque. Only one of the two force introduction connections is shown in the drawings.

[0014] The force introduction connection 20 consists of a cylindrical portion 21 in the form of a tube or spigot and a connection flange 22. The cylindrical portion 21 configured as a tube here is provided at its free end with an axially parallel peripheral toothing 23, the external diameter of which is slightly larger than the internal diameter of the hollow shaft 10. The cylindrical portion 21 is axially pressed in with the end having the peripheral toothing 23 in the end of the hollow shaft 10, the peripheral toothing 23 cutting slightly into the inner wall of the hollow shaft 10 and thereby producing a rotationally fixed connection between the cylindrical portion 21 and the hollow shaft 10. A sleeve-shaped support 11, which prevents the end of the hollow shaft 10 widening and the rotationally fixed connection thereby being lost is fitted on the outside of the hollow shaft 10 in the region of the peripheral toothing 23 of the portion 21.

[001 5]The cylindrical portion 21 projects by a length S from the hollow shaft 10. The length S corresponds to the spacing between the hollow shaft 10 and the connection flange 22.

[001 6]So far, the drive shaft according to the invention shown corresponds to the drive shafts known, for example from the document DE 30 07 896 Al. In this document and, for example, in the two other documents listed at the outset, all relevant details with regard to materials, production methods, dimensions etc. can be found, so the person skilled in the art does not need any further explanations in this regard. It is obvious that optionally also only one force introduction connection of the type described may be provided [0017]If the vehicle, in which the drive shaft is installed, suffers a collision, the forces occurring in this case may in some circumstances also act on the drive shaft The drive shaft according to the invention can be compressed in the axial direction and can thus absorb some of the collision energy. If an axial force caused by a collision acts on the force introduction connection 20 and exceeds a certain threshold, the cylindrical portion 21 is pressed into the hollow shaft 10 until, in an extreme case, the connection flange 22 is applied to the hollow shaft 10. This axial displacement of the cylindrical portion 21 or the entire force introduction connection 20 is counteracted by a resistance force F, which is produced substantially from the friction of the cylindrical portion 21 on the inner wall of the hollow shaft 10. The peripheral toothing 23 of the portion 21 to a certain extent ploughs, in the process, through the inner wall of the hollow shaft 10. The integral of the resistance force F over the displacement path s corresponds to the absorbed collision energy (Fig. 5).

[0018] The absorbed collision energy in the drive shaft known from the document DE 30 07 896 Al is relatively small. Although at the outset a relatively high resistance force is produced, this already sharply decreases after a short displacement path because the hollow shaft is then exploded. This is where the invention comes into play.

[0019]According to a main aspect of the invention, the length S of the part of the cylindrical portion 21 projecting from the hollow shaft 10 and therefore the maximum displacement path of the force introduction connection 20 is selected to be at least 50 to 150 mm, preferably around 80 to 100 mm. Furthermore, an additional reinforcement 30 is provided axially adjacent to the support 11 on the outside of the hollow shaft 10 and extends over a length which is approximately the same size as the length S of the part of the cylindrical portion 21 projectrng from the hollow shaft 10. The axial extent of the additional reinforcement 30 thus corresponds approximately to the maximum displacement path of the cylindrical portion 21 or the entire force introduction connection 20. The course of the resistance force F occurring over the displacement path s can be influenced by means of this additional (radial) reinforcement 30 for the hollow shaft 10 in such a way that the absorbed collision energy is drastically increased, it is advantageous, in particular, if the resistance force F over the entire displacement path s of at least 50 to 150 mm does not drop below a certain minimum threshold of, for example 40 to 60 kN, as is illustrated in the graph of Fig. 5. The curve 40 shows a typical course of the resistance force.

[0020]It will be understood that the resistance force F and its course over the displacement path s can be influenced by suitable configuration, dimensioning and axial distribution of the strength properties of the additional reinforcement 30 within broad limits. The optimal configuration for the respective application can be determined empirically by a few tests and the person skilled in the art does not need any more detailed explanations in this regard.

[0021]It is expedient if the additional reinforcement 30 has slightly lower radial rigidity than the support 11 at the end of the hollow shaft 10. The additional reinforcement 30 may consist of fibre-reinforced plastics material. If the reinforcement 30 is applied to the hollow shaft in a working cycle that is separate from the production of the hollow shaft 10, it is possible to use economical material sold by the metre for the hollow shaft 10.

[0022] The initial resistance force F should not be too high. Practical values are about to 120 kN. This is achieved by suitable dimensioning of the hollow shaft 10 and its support 11.

[0023] Instead of the tubular configuration of the additional reinforcement 30 shown in Figs. 1 and 2, this may also consist of individual rings 31 made of fibre-reinforced plastics material or optionally also of metal (Fig. 3). Alternatively, wire rings 32 may also be used, for example, as shown in Fig 4. The wires may in this case consist of metal or, for example, also a fibre-reinforced plastics material (for example a fibre bundle bound by a thermoplastic).

[0024] Prefabricated parts, which are assembled on the finished hollow shaft 10 by adhesion, pressing on or shrinking on, can also be used for the additional reinforcement 30 or 31 or 32.

[0025] As Fig. 6 shows, it is also possible to implement the functions of the support 11 and the additional reinforcement by a one-piece component, which is designated 33 in Fig. 6. This component may also be graduated with respect to its thickness, as Fig. 7 illustrates. The component is designated 34 there. By suitable dimensioning this allows adjustment to desirable energy absorption values over the displacement path of the portion 21.

[0026] It is furthermore also possible to arrange the additional reinforcement 33 not on the outside, but in the interior of the hollow shaft 10. This variant embodiment is shown in Fig. 8. In practice the hollow shaft 10 is in this case wound over the reinforcement 33 or glued to it in a separate production process. The reinforcement 33 also simultaneously takes on the function of the support 11 here.

[0027]Finally it is also possible to likewise produce the force introduction connection completely or partially from fibre-reinforced plastics material, in particular.

[0028]The drive shalt according to the invention is distinguished by a high energy absorption capacity and is simultaneously relatively very easy and economical to produce.

Claims

S

Claims 1. Collision-energy-absorbing drive shaft for motor vehicles with a cylindrical hollow shaft (10) made of fibre-reinforced plastics material and a force introduction connection (20) with a connection flange (22) and a cylindrical portion (21), the free end of which is provided with an axially parallel peripheral toothing (23) and is pressed into the end of the hollow shaft (10) provided with a sleeve-shaped support (11), wherein the peripheral toothing cuts into the inner wall of the hollow shaft and thereby connects the cylindrical portion and the hollow shaft to one another in a rotationally fixed manner, and wherein the cylindrical portion (21) projects by a length (S) from the hollow shaft (10) and in the event of a collision, with partial absorption of the collision energy, can be displaced against a resistance force (F) by this length axially into the hollow shaft, characterised in that an additional reinforcement (30; 31; 32; 33; 34) is arranged on the hollow shaft (10) axially adjacent to the support (11) said reinforcement extending in the axial direction substantially over a length corresponding to the length (S) by which the cylindrical portion (21) projects from the hollow shaft (10).
2. Drive shaft according to claim 1, characterised in that the length (S) by which the cylindrical portion (21) of the force introduction connection (20) projects from the fibre-reinforced hollow shaft (10) is at least about 50 to 150 mm, preferably about 80 to 100 mm.
3. Drive shaft according to any one of the preceding claims, characterised in that the rigidity of the additional reinforcement (30; 31; 32; 33; 34) is equal to or less than the rigidity of the support (11) in the region of the peripheral toothing (21).
4. Drive shaft according to any one of the preceding claims characterised in that the additional reinforcement (30; 31; 32) consists of a material which is comparatively elastic in relation to the support (11) in the region of the peripheral toothing (23).
5. Drive shaft according to any one of the preceding claims, characterised in that the additional reinforcement (30; 31; 32; 33; 34) consists of fibre-reinforced plastics material.
6. Drive shaft according to any one of the preceding claims, characterised in that the additional reinforcement consists of individual rings (31; 32).
7. Drive shaft according to claim 6, characterised in that the rings (32) are formed from metal-reinforced or fibre-reinforced plastics material wires.
8. Drive shaft according to any one of the preceding claims, characterised in that the additional reinforcement (30; 31; 32; 33; 34) is dimensioned such that the axial resistance force (F) does not drop below 40 to 60 kN over the entire displacement path (s) of the cylindrical portion (21).
9. Drive shaft according to any one of the preceding claims, characterised in that the hollow shaft (10) with its support (11) and the additional reinforcement (30; 31; 32; 33; 34) are dimensioned such that the axial resistance force (F) does not increase above 100 to 120 kN.