WO2005053990A1

WO2005053990A1 - Tubular drive shaft, in particular a cardan shaft for a motor vehicle

Info

Publication number: WO2005053990A1
Application number: PCT/EP2004/013703
Authority: WO
Inventors: Christine Kienhöfer; Eckhard Morlock
Original assignee: Rotaform Gmbh
Priority date: 2003-12-03
Filing date: 2004-12-02
Publication date: 2005-06-16

Abstract

The invention relates to a tubular drive shaft, in particular a cardan shaft for a motor vehicle. Said shaft comprises a first section (1) with a first diameter D, a second section (2) with a second diameter d, the measurement d being smaller than the measurement D and receives a linear guide tube (6) comprising a first tubular section (8), which extends along the first section (1) of the drive shaft (11), and a second tubular section (7), which protrudes into the second section (2) of the drive shaft (11). According to the invention, the clearance of the drive shaft (11) in the vicinity of the first tubular section (8) is reduced, at least at one point (12), to approximately the external diameter of the guide tube (6).

Description

RF02E002WO / wh04s05 / TW / wh / 23.11.2004

ROTAFORM GmbH, Dieselstrasse 2, 75203 Koenigsbach-Stein

Tubular drive shaft, in particular cardan shaft for a motor vehicle

Description:

The invention relates to a drive shaft with the features specified in the preamble of claim 1.

From DE 41 13 709 C2 a cardan shaft is known which has a first section with a first diameter and a second section with a second diameter, the second diameter being smaller than the first diameter. There is a transition section between the first section and the second section, in which the diameter decreases from the larger first diameter to the smaller second diameter. The purpose of this design is that when a motor vehicle collides with an obstacle, the cardan shaft can be pushed together with as little energy consumption as possible by deforming the transition section of the pushes the first section of the cardan shaft with the larger diameter over the second section of the cardan shaft with the smaller diameter. There is a risk that the cardan shaft will buckle. This is undesirable because the buckling results in an uncontrolled deformation behavior. DE 41 13709 C2 therefore discloses providing a guide tube in the cardan shaft which, with a section of smaller diameter, is firmly inserted in the second, thinner section of the cardan shaft. From there, the guide tube extends into the first, thicker section of the cardan shaft and there has a section with a diameter which approximates the inside diameter of the first section of the cardan shaft. So that the guide tube with its larger diameter end does not get caught on the inside of the first, larger diameter section of the drive shaft in the event of a collision of the vehicle, seizes up and therefore can no longer fulfill its guiding task, it is known to attach the guide tube to rejuvenate its end. If, in the event of an impact, the two sections of the cardan shaft slide into one another, the guide tube effects a guide which prevents the cardan shaft from buckling, so that the cardan shaft only absorbs deformation energy until its second section breaks away from its first section.

It is also known to further develop a cardan shaft of the type described in DE 41 13709 C2 in such a way that there is an annular bead in the outside of the transition section between the first section of larger diameter and the second section of smaller diameter of the cardan shaft , which is arranged coaxially to the longitudinal axis of the propeller shaft. This bead is intended to determine the point at which the transition section begins to fold in the event of an impact and later tears. It is known to produce such a cardan shaft with a bead in the transition section by starting from a tube which has the diameter that the cardan shaft should have in its first section. The bead is rolled or turned into this tube at the point where the transition section is later to be located, for which purpose the tube is acted on in a radial direction. The second section of the cardan shaft with the smaller diameter and the transition section are then formed by kneading, pressing or pulling the tube. The prefabricated guide tube is then inserted through the first section of the cardan shaft and pressed into the second section, that is the section with the smaller diameter.

In the known drive shaft, the manufacture of the guide tube starting from a straight cylindrical tube is complex.

The present invention has for its object to show a way how a generic drive shaft, in which there is a guide tube, can be manufactured with less effort.

This object is achieved by a drive shaft with the features specified in claim 1. Advantageous developments of the invention are the subject of the dependent claims.

With the drive shaft according to the invention, a departure from the state of the art is made in that, instead of a guide tube with a diameter that changes greatly over its length, it receives a guide tube with a diameter that changes less or even with a substantially constant diameter. The adjustment of the diameter of the guide tube and the diameter of the tubular drive shaft to one another, which is necessary for the purpose of the guide tube, is obtained by extending the first tube section of the guide tube into a region of the drive shaft where the clear width of the drive shaft at least at least one point is almost reduced to the outer diameter of the guide tube. By the fact that the clear width of the drive shaft is at least almost reduced to the outside diameter of the guide tube, it is meant that the distance between the guide tube and the inside of the drive shaft is so small, that in the event of a collision of the vehicle with an obstacle, the kink protection desired for the drive shaft is achieved and that the first tube section of the guide tube extending in the first section of the drive shaft can move therein, while the drive shaft with its thinner second section moves into its thicker one first section pushes.

The kink protection assumes that there is a guide between the outer tube of the drive shaft and the guide tube at at least one point. The location of this point is to be selected so that it does not prevent the first and second sections of the drive shaft from being pushed together until they tear off and, furthermore, does not prevent the vehicle manufacturer from responding in the event of a crash. The location at which the clear width of the drive shaft is reduced in its first section is therefore preferably at the end of the path specified for the crash, via which the thinner second section of the drive shaft should be able to slide into its thicker first section. The position of the drive shaft with a reduced clear width covers an end section of the guide tube. In the event of an impact, the entire remaining length of the first tube section of the guide tube is available for pushing the drive shaft together.

If several locations are provided at which the clear width of the drive shaft is reduced, these locations are expediently close to one another. However, preferably only one such location is provided.

In order to implement the invention, the diameter jump between the first and the second tube section of the guide tube can be reduced compared to the state of the art and, for compensation, the diameter of the first section of the tubular drive shaft can be reduced at a point from the value D to a value which is greater than d. This simplifies the manufacture of the guide tube and leads overall to greater stability of the tubular drive shaft. The invention is preferably implemented in such a way that the guide tube has a constant or approximately constant outer diameter over its entire length, so that no or practically no reshaping of the guide tube is required. The adaptation of the guide tube to the surrounding tubular drive shaft, which is intended to provide guidance in the event of a crash, can then either be carried out by constructive measures in the first section of the drive shaft with the larger diameter D or in a third section of the drive shaft with a smaller diameter adjoining the first section ; this third section adjoins the side of the first section facing away from the second section of the drive shaft.

There are different possibilities in the first section of the drive shaft to reduce its clear width. A first possibility is to reduce the diameter of the drive shaft itself at at least one point, for example by rolling in a bead or by kneading the first section of the drive shaft over part of its length, which is short against the length of the first section of the Drive shaft should be. Such a local reduction in the diameter of the drive shaft does not unduly reduce its stability.

Another possibility is to provide a support ring between the guide tube and the first section of the drive shaft at the at least one point. This support ring is to be secured against sliding either on the guide tube or on the inside of the drive shaft.

Such a support ring is particularly advantageous if it has a vibration-damping structure, because it not only offers the desired guidance and the resulting anti-kink protection, but also dampens vibrations of the drive shaft and its guide tube, which reduces the noise and a possible Allow the drive shaft to run out of round. For example, absorbers, which are, are suitable as support rings vibration-damping composite rings made of rubber and metal, in particular rubber and lead. A vibration-damping support ring is preferably attached to the inside of the drive shaft; the support ring is preferably pressed into the drive shaft. If vibration damping is not important, it is preferred to attach the support ring to the guide tube. Fastening the support ring on the guide tube is also particularly advantageous because it allows a shorter support tube than if the support ring is attached to the inside of the drive shaft, namely the guide tube can be shorter by the length by which the drive shaft is in the event of a crash can be pushed together. The further consequence is a weight saving that is most welcome in the automotive industry.

A section with a smaller diameter d preferably adjoins on both sides of the first section of the drive shaft, which has the larger diameter D. In this case, the guide tube, which is firmly in one of these sections of the drive shaft with the smaller diameter d, can be extended into the other section with the diameter d. In this case, no additional measures to reduce the diameter are required on the outer tube of the drive shaft and, apart from its extension, no special measures are required on the guide tube either, except that care must be taken to ensure that it is in one section of the drive shaft with the smaller diameter d is stuck, but is movable in the other section with the smaller diameter d.

In order to be able to fix the guide tube with its second tube section in the second portion of the drive shaft, the guide tube preferably has longitudinally extending or helically extending ribs on its outside, longitudinal ribs being particularly preferred. With these ribs, which do not have to extend over the entire length of the guide tube, but can be limited to the second tube section, and for which only a small height is required, the guide tube can be in the second section of the Drive shaft are pressed in if the guide tube has a small oversize compared to the inner diameter of the second section of the drive shaft, taking into account the ribs.

Since finned tubes are commercially available, the use of such tubes in a drive shaft according to the invention is particularly cost-effective. Ribs that are only part of the length of the guide tube can be formed by pressing a ribbed mandrel into the guide tube.

The fastening of the guide tube in the second section of the drive shaft can, however, also take place as is known in the prior art, namely in that the second tube section of the guide tube is slightly corrugated or is provided in another way with bulges, the height of which is dimensioned in this way is that the desired press fit of the guide tube can be achieved in the second section of the drive shaft.

Another possibility for the positive and / or non-positive fixing of the guide tube in the second section of the drive shaft is to provide the second section of the drive shaft with indentations which act on the guide tube before or after the guide tube is inserted.

The invention has significant advantages:

♦ Instead of an elaborately shaped guide tube with a diameter that changes greatly over its length, the invention in principle manages with a straight guide tube that has a constant diameter over its length, with any local bulges for the purpose of non-positive and / or positive fixing of the Guide tube is disregarded in the drive shaft. ♦ The additional effort by reducing the clear width of the first section of the drive shaft or by extending the Guide tube is far overcompensated by the savings that the use of a guide tube with a constant or approximately constant diameter entails. ♦ If a support ring is used, vibration damping can take place at the same time.

Three embodiments of the invention are shown in the accompanying drawings, in which the same or corresponding parts are designated by the same reference numerals.

FIG. 1 shows a drive shaft according to the invention with an inserted guide tube in a longitudinal section,

FIG. 2 shows detail Y from FIG. 1 enlarged five times,

FIG. 3 shows a second exemplary embodiment of a drive shaft according to the invention in a representation as in FIG. 1,

FIG. 4 shows the cross section A-A according to FIG. 3,

FIG. 5 shows detail Y from FIG. 4, enlarged twice,

FIG. 6 shows a third exemplary embodiment of a drive shaft according to the invention in a representation corresponding to FIG. 1,

Figure 7 shows a fourth embodiment of a drive shaft according to the invention in a representation corresponding to Figure 1, and

FIG. 8 shows a fifth exemplary embodiment of a drive shaft according to the invention in a representation corresponding to FIG. 1. The drive shaft 11 shown in Figure 1 is formed from a cylindrical tube with the outer diameter D. This tube is first formed over part of its length, in particular by drawing or kneading. As a result, a first section 1 of the tube remains at its original diameter D and a second section 2 with a second, smaller outside diameter d is created. So that in the event of an impact, section 1 can slide over section 2 or section 2 can slide into the section

I can push in, the outer diameter d is at least the wall thickness of the first section 1 smaller than the inner diameter of the section 1. Between the sections 1 and 2 of the drive shaft there is a transition section 3 with an S-shaped course in the longitudinal section, the greatest slope relative to the longitudinal axis 4 of the drive shaft is preferably 45 ° C to 80 ° C. In the outside and / or the inside of the transition section 3 there is preferably an annular bead which is intended to ensure that the drive shaft pushes together at a predetermined point in the event of an impact and finally breaks off.

A guide tube 6 is inserted in the drive shaft 11. The guide tube 6 is a rectilinear tube which has a substantially constant diameter over its entire length, both the inside diameter and the outside diameter. The restriction "essentially" is made because the second pipe section 7, which is in the second section 2 of the drive shaft

I stuck, is wavy; one of the shafts 15 is shown enlarged as detail Y in FIG. The shafts 15 only increase the diameter of the guide tube 6 by a fraction of a millimeter, sufficient to be able to press the second tube section 7 into the second section 2 of the drive shaft 1, so that it is non-positively fixed therein.

The first section 1 of the drive shaft 11 with the diameter D connects its second section 2 to a third section 10. The second section 2 and the third section 10 generally correspond in diameter d, which is less than D. The majority of the first section 1 of the drive shaft 11 has been broken away for reasons of clarity.

Only at a narrow point 12, up to which the guide tube 6 extends with its first tube section 8 in the thicker first section 1 of the drive shaft 11, in this first section 1 is the inside diameter of the drive shaft 11 reduced to the outside diameter of the guide tube 6, whereby there is still a slight play between the two, which ensures that the guide tube 6 is guided in the reduced diameter section 13 of the first section 1 of the drive shaft 11. This section 13 requires only a small length for its management task. Good results are already achieved with a length of 1 to 2 cm; In addition, there are the two transitions 17 and 18 to the adjacent partial sections of section 1 with the larger diameter D.

In the normal position, the front end of the guide tube 6 lies at the end of the section 13 of the drive shaft 11, as shown in FIG. 1, or protrudes slightly beyond it. A taper can be dispensed with at this end of the guide tube 6, because if the second section 2 of the drive shaft 11 slides into the first section 1 of the vehicle in the event of an impact, then the front end of the guide tube 6 moves into the adjoining free space of the first section 1 of the drive shaft 11 with the larger diameter D, the wall of which it does not touch as long as the drive shaft 11 does not buckle. But this is prevented by the guide tube 6.

The exemplary embodiment shown in FIGS. 3 to 5 differs from the exemplary embodiment shown in FIGS. 1 and 2 in that a tube is used as the guide tube 6, which is not corrugated, but has three longitudinal ribs 16, which have a circumferential angle of 120 ° are separated from each other. The position of the ribs 16 is shown in Figure 4, the shape of the ribs 16 in Figure 5. They increase the outside diameter of the Guide tube 6 locally by a fraction of a millimeter, sufficient to be able to press the second tube section 7 of the guide tube 6 firmly into the second section 2 of the drive shaft 11. More than three ribs could also be provided on the circumference of the guide tube 6.

The exemplary embodiment shown in FIGS. 3 to 5 also differs from the exemplary embodiment shown in FIGS. 1 and 2 in that the two transitions 17 and 18 are flatter than the transition section 3, so that the drive shaft 11 does not also attach itself in the event of an impact turns and pushes the transitions 17 and 18, but only on the steeper transition section 3.

The embodiment shown in FIG. 6 differs from the embodiment shown in FIGS. 1 and 2 in that the first section 1 of the drive shaft 11 does not have a section 13 with a reduced diameter. Instead, a support ring 14 is pressed into the drive shaft 11 at a corresponding point 12, specifically before the second section 2 or the third section 10 of the drive shaft 11 with the smaller diameter d has been formed. In this support ring 14, the front end of the guide tube 6 is guided longitudinally with little play.

Instead of pressing the support ring 14 into the drive shaft 11, one could also glue it in or fix it in a form-fitting manner, for example by indentations in the wall of the drive shaft 11. The support ring 14 could also be pressed onto the guide tube 6 so that it fits together with it in the section 1 of the drive shaft 11 moves.

The exemplary embodiment shown in FIG. 7 differs from the example shown in FIGS. 3 to 5 in that the diameter jump from the diameter D in the first section 1 of the drive shaft 11 to the reduced diameter in the section 13 was reduced. To compensate for that a guide tube 6 is used, the first tube section 8 of which has been correspondingly enlarged compared to the second tube section 7, so that the desired guidance occurs at the constriction 12. The guide tube 6 is inserted before the third section 10 of the drive shaft 11, which is smaller in diameter, is formed. The transitions 17 and 18 are flatter than the transition section 3, which ensures that, in the event of an impact, the drive shaft 11 pushes together starting from the transition section 3 and finally breaks off.

The exemplary embodiment shown in FIG. 8 differs from the exemplary embodiment shown in FIGS. 3 to 5 in that there is no constriction at all in the first section 1 of the drive shaft 11. Rather, the guide tube 6, which is fixed with its second tube section 7 in the second section 2 of the drive shaft 11, is extended with its first tube section 7 into the third section 10 of the drive shaft 11 and fulfills its guiding task in cooperation with this third section 10. This Embodiment is characterized by particularly low manufacturing costs.

LIST OF REFERENCE NUMBERS:

1. first section of 11

2. second section of 11

3rd transition section 4th longitudinal axis

5. Beading

6. Guide tube

7. second pipe section

8. first pipe section 9.

10. third section of 11

11. Drive shaft

12th constriction

13. Section with reduced diameter 14. Support ring

15th wave

16th rib

17th transition

18th transition

Claims

Expectations:

1. A tubular drive shaft, in particular a propeller shaft for a motor vehicle, which has a first section (1) with a first diameter D and a second section (2) with a second diameter d, where d is smaller than D, and which has a straight guide tube ( 6) which has a first pipe section (8) which extends in the first section (1) of the drive shaft (11) and a second pipe section (7) which is in the second section (2) of the drive shaft (11), characterized in that in the region of the first tube section (8) the clear width of the drive shaft (11) is at least at least almost reduced to the outside diameter of the guide tube (6) at at least one point (12).

2. Drive shaft according to claim 1, characterized in that the two tube sections (7, 8) of the guide tube (6) in the outside diameter i.w. do not differentiate.

3. Drive shaft according to claim 1 or 2, characterized in that its clear width at the end of the guide tube (6), covering an end portion of the guide tube (6), is at least almost reduced to the outer diameter of the guide tube (6).

4. Drive shaft according to claim 1, 2 or 3, characterized in that its clear width along the first tube section (8) of the guide tube (6) is reduced only at one such point (12).

5. Drive shaft according to one of the preceding claims, characterized in that the diameter of the drive shaft (11) is reduced at the at least one point (12).

6. Drive shaft according to claim 5, characterized in that the point (12) at which the diameter of the drive shaft (11) is reduced is a constriction in the first section (1).

7. Drive shaft according to claim 5, characterized in that the point (12) at which the diameter of the drive shaft (11) is reduced, adjoins the first section (1) of the drive shaft (11), specifically on the second section (2) the side facing away from the drive shaft (11).

8. Drive shaft according to one of claims 1 to 6, characterized in that a support ring (14) between the guide tube (6) and the first section (1) of the drive shaft (11) is provided at the at least one point (12).

9. Drive shaft according to claim 8, characterized in that the support ring (14) on the guide tube (6) is attached.

10. Drive shaft according to claim 8, characterized in that the support ring (14) has a vibration-damping structure.

11. Drive shaft according to claim 10, characterized in that the support ring (14) on the inside of the first section (1) of the drive shaft (11) is attached.

12. Drive shaft according to one of the preceding claims, characterized in that the guide tube (6) on its outside has longitudinal or helical ribs (16).

13. Drive shaft according to claim 12, characterized in that the ribs (16) are only on the second tube section (7) of the guide tube (6).

14. Drive shaft according to one of claims 1 to 11, characterized in that the guide tube (6) in its second tube section (7) has one or more bulges (15).

15. Drive shaft according to claim 14, characterized in that the guide tube (6) is corrugated in its second tube section (2).

16. Drive shaft according to one of the preceding claims, characterized in that it has one or more indentations in its second section (2).

17. Drive shaft according to claim 5 or 6, characterized in that the constriction (12) has transitions (17, 18) to the first section (1) with the diameter D, which are flatter than the transition section (3).