WO2010086269A1 - Telescopic steering shaft - Google Patents

Abstract

The invention relates to a telescopic steering shaft 1 comprising an outer pipe 2, in which an inner pipe 3 can be moved axially in a guided manner. A seal 5 seals an intermediate space 14 between the inner pipe 3 and the outer pipe 2 at the end of the outer pipe 2. A retaining cap 4 comprising an interior space 9 for accommodating the seal 5 is provided. The retaining cap 4 has an inner diameter that is matched to the outer diameter of the end of the outer pipe 2 in such a way that the retaining cap 4 can be slipped onto the end of the outer pipe 2 in an at least approximately flush manner. The retaining cap 4 comprises a circumferential wall 10 having at least one locking element 11. The retaining cap 4 further comprises a front ring area 12, which extends radially inward starting from the circumferential wall 10 and surrounds the inner pipe 3 at a distance. The seal 5 lies against the inside of the ring area 12. At least one receptacle 13 is further provided on the outer circumference of the outer pipe 2 for the at least one locking element 11. The receptacle 13 and the at least one locking element 11 are arranged relative to each other in such a way that after the locking element 11 is locked into the receptacle 13, the intermediate space 14 between the inner pipe 3 and the outer pipe 2 is sealed.

Description

 Telescopic steering shaft

The invention relates to a telescopic steering shaft with an outer tube, in which an inner tube guided axially displaceable, according to the preamble of claim 1.

From the general state of the art telescopic steering shafts (which are also referred to as steering columns) are known, which usually consist of an outer tube in which an inner tube for telescoping, either via a sliding seat or bearings is mounted axially displaceable. For sealing against environmental influences, such as dirt, dust, water and the like, the gap between the inner tube and the outer tube is closed by a sealing system at the end of the outer tube.

Such steering shafts are normally used in passenger vehicles to change the positioning of the steering wheel in a driver-friendly manner.

For fixing or for holding the sealing system and the most here in this area with built-bearing bush, it is known to roll the outer tube. For this purpose, the end of the outer tube is bent inwards in such a way that the seal, after it has optionally been inserted together with the bearing bush in the intermediate space between the outer tube and the inner tube, can no longer escape.

This type of attachment or fixation of the sealing system and optionally the bearing bush has the disadvantage that after the actual assembly of the steering shaft, a costly forming process must be performed. The forming process also has the disadvantage that a surface protection in the form of a paint can be applied only after completion of the forming process, since the Rollierlippe, ie the bent portion of the outer tube after forming is blank. In a previously galvanized pipe surface, the resistance, for example, against salt, thereby significantly reduced. In terms of manufacturing technology, it is advantageous to apply the coating or the surface protection before assembly and not afterwards.

The present invention has for its object to provide a telescopic steering shaft (or steering column), in which the gap between the inner tube and the outer tube is reliably protected from environmental influences, the steering shaft should be simple and inexpensive to produce.

Due to the holding cap according to the invention and its interaction with at least one receptacle on the outer circumference of the outer tube, a gap between the outer tube and the inner tube is reliably protected from environmental influences. The closing of the gap is carried out by attaching the retaining cap on the end of the outer tube and a subsequent latching of the locking system formed by the locking elements and the recording.

Basically, it does not depend on the fixing of the retaining cap, whether the retaining cap has locking elements in the form of locking lugs or locking tabs, and the receptacles in the outer periphery of the outer tube in the form of partially or completely circumferential grooves, notches or recesses are formed. Basically, a locking system can be designed to be complementary, d. H. the locking elements described below on the retaining cap can also be formed on the outer circumference of the outer tube and the receptacles corresponding to the retaining cap. Under the definition latching elements and recordings are intended to fall within the scope of the invention in each case both variants. However, it is advantageous to form latching elements on the retaining cap in the form that they are biased in the radial direction at least slightly movable or (preferably resilient), so that they engage in corresponding receptacles, for example in the form of depressions and the like, on the outer circumference of the outer tube can.

The inventive solution avoids a costly forming process at the end of assembly. It is therefore possible to apply a surface protection on the parts involved, in particular the outer tube before mounting. Damage to the surface protection by the assembly is no longer expected by the inventive solution. The retaining cap according to the invention can be mounted quickly and easily without a substantial device or machine effort. The steering shaft or the steering shaft is completed after placing the retaining cap as the last assembly operation, a subsequent painting or reworking is not necessary.

The outer tube is preferably formed as a steel tube, preferably with a zinc-nickel coating, and is protected against damage with a surface-mounted before mounting surface protection.

According to the invention it can be provided that the holding element is already provided with an example vulcanized sealing system or a seal. In this case, a gap between the outer tube and the inner tube can be closed directly by the application of the retaining cap. Optionally, the retaining cap can also be provided with a multi-part seal, for example, such that a part of the seal between the retaining cap and the outer periphery of the outer tube and the other part of the seal between the retaining cap and the inner tube seals.

It is advantageous if the seal is formed as a separate part of the holding cap. The seal can be inserted, for example, in the retaining cap. The seal may be arranged in a sealing manner between the outer tube and the retaining cap after the latching element has latched into the receptacle. Preferably, it can be provided that the seal between an end face of the end of the receiving tube and the retaining cap is axially biased. A design of the seal and the retaining cap as separate parts is easy and inexpensive. The retaining cap can take over simple tolerance adjustments the task of axially biasing the seal against the end face of the outer tube in order to ensure a particularly good seal on the outer tube.

It is advantageous if the annular surface of the retaining cap surrounds the inner tube such that only a narrow, annular gap remains. It can be provided that the seal has a circumferential wiper lip, which on the inner tube or the outer surface of the peripheral wall of the inner tube sealingly rests. The wiper lip can be arranged in the narrow, annular gap between the annular surface of the retaining cap and the outer tube or project into this gap. Due to the wide pulling down of the end face formed on the retaining cap annular surface, the wiper lip of the seal is best protected against external damage.

It is advantageous if the retaining cap conforms or fits snugly against the outer contour of the outer tube in the region of the tube end such that the outer diameter of the outer tube is only slightly enlarged by the retaining cap. For this purpose and to support a good sealing function, the invention provides that the inner diameter of the retaining cap is adapted to the outer diameter of the end of the receiving tube such that the retaining cap is at least approximately flush mounted on the end of the outer tube.

As a result, inter alia, a simple passage of the steering shaft through the cabin passage of a car or a commercial vehicle is made possible.

Another function of the retaining cap is that it can ensure a minimum extraction force. In case of sudden or strong pulling on the inner tube against the stop when the steering shaft is fully extended, the steering shaft must not be able to be pulled apart. This may be the case, for example, when pulling on the steering shaft for alignment of the cabin during assembly on the chassis.

The latching lugs of the preferably self-latching retaining cap can be configured as desired. Preferably, the retaining cap has two, three, four or more locking elements. The locking elements are preferably evenly distributed in a preferably radial plane around the circumference, ie along the peripheral wall. Preferably, the distance between the locking elements is in each case substantially identical. The recordings in the outer circumference of the outer tube can be designed accordingly. It is conceivable in principle that the outer tube on the outer circumference has a circumferential, preferably narrow groove into which the locking elements can engage. However, it is also possible for each locking element form a specifically positioned recording, for example in the form of a groove, a notch or a return.

Preferably, the seal may have a peripheral sealing bead, which adjoins the end face of the outer tube in the installed state.

The locking elements may be formed as locking lugs. The latching elements can also be designed as latching tabs which extend from the peripheral wall of the retaining cap against the slip-on direction, d. H. in the direction of the annular surface, extend. The free end of the locking elements may be bent in the direction of the interior of the retaining cap.

In a design of the locking elements with locking lugs an inwardly bent free end is not mandatory. It may alternatively be provided that the locking lugs bent when plugging, d. H. be bent to the outside, then snap into place when reaching the end position in corresponding recesses or otherwise formed recordings or lock. In this case, various embodiments are obvious to the person skilled in the art.

In general, it is advantageous for the design of the latching system if the latching elements are resiliently biased or radially biased in the direction of the interior of the retaining cap, so that the latching elements engage independently in the receptacles lying deeper in relation to the outer diameter of the outer tube.

It is advantageous if a bearing bush formed as a separate part is received in the interior of the retaining cap. The bearing bush can serve for the displaceable mounting of the inner tube in the outer tube. From the general state of the art bearing bushes are known in a variety of configurations. An embodiment of the bearing bush as a sliding fit or the like is advantageous. Also possible would be a bearing bush with rolling elements.

According to the invention it can be provided that first the bearing bush is inserted into a space between the inner tube and the outer tube, then the seal can be plugged onto the inner tube and from the Bearing bush and the seal formed package can be fixed by the retaining cap. However, a combination of bushing and scraper is preferable as a part. Seal and bearing bush are preferably manufactured in a tool as a two-component part.

The retaining cap may be formed of any suitable material, such as plastic or metal. Particularly suitable is an embodiment as a coated sheet metal part or stainless steel, since in addition to the high strength required for the locking lugs also an advantageous corrosion protection of the retaining cap is given.

The peripheral wall of the retaining cap may preferably have a substantially circular peripheral wall, whereby the retaining cap can be pushed in a simple manner flush with the end of an outer tube. It may be advantageous in this case if the peripheral wall slightly deviates from the circular shape in such a way that partial bulges are provided distributed around the circumferential wall. Preferably, the outer tube has an outer periphery which deviates from the circular shape by bulges. By adapting the retaining cap to the outer circumference of the outer tube, a defined positioning of the retaining cap is achieved in addition to the accurate connection.

The self-locking cap has the advantage of a simple and safe installation by the engagement of the locking elements on the circumference of the outer tube. It can be achieved in a simple manner afflicted with little tolerance axial preload of the seal. The solution according to the invention also makes it possible to ensure a minimum extraction force and is inexpensive compared to the known solutions from the prior art.

Advantageous embodiments will become apparent from the other dependent claims. An exemplary embodiment of the invention is shown in principle below with reference to the drawing.

It shows: Figure 1 is a slightly perspective side view of a steering shaft with a partial section in the region of the end of an outer tube and with a sectional view of a retaining cap, a seal and a bearing bush prior to assembly.

Fig. 1a is a detail of a one-piece bearing bush / seal with a sealing bead;

Fig. 2 is a reduced view of the steering shaft of Figure 1 after attaching the retaining cap on the end of the outer tube.

Fig. 3 is a side view of the illustration of FIG. 2;

Fig. 4 is a rear view of a retaining cap;

Fig. 5 is a sectional view along the line V-V of Fig. 4;

Fig. 6 is a sectional view taken along the line Vl-Vl of Fig. 4; and

7 is an enlarged view of the detail VII of FIG .. 6

Telescopic steering shafts whose function and field of application, in particular in passenger vehicles and commercial vehicles, are well known from the general state of the art, for which reason only the features essential to the invention will be discussed in more detail below.

Figures 1 to 3 show a section of a telescopic steering shaft 1, which is also referred to as a steering shaft. The telescopic steering shaft 1 has an outer tube 2, in which an inner tube 3 is guided axially displaceable.

As is apparent from the illustration of FIG. 1, the telescopic steering shaft 1, a retaining cap 4, a seal 5 and a bearing bush 6, which are each formed as separate parts. The seal 5 may have any suitable structure and optionally also consist of several parts. In the exemplary embodiment, the seal 5 encloses the inner tube 3 flush. The seal 5 is therefore formed substantially annular. The seal 5 has a height or an outer diameter which corresponds approximately to the outer diameter of the outer tube 2.

The seal 5 has a wiper lip 7 and an annular groove 8 arranged around it. The wiper lip 7 protrudes in the axial direction beyond the main plane of the seal 5 and adjoins the peripheral wall of the inner tube 3.

The bearing bush 6 may have a conventional structure known from the prior art. In the exemplary embodiment it is provided that the bearing bush 6 is formed as a plain bearing bush.

As can be seen from FIGS. 1 and 2, the bearing bush 6 and the seal 5 have means for holding them together at least approximately positively. The bushing 6 has at its the sealing 5 facing end side projections 20, elevations, knobs or the like. The seal 5 has recesses 19, recesses or generally receptacles, in which the projections can penetrate the at least approximately positive connection. The recesses 19 and the projections 20 are each formed complementary to each other.

Basically, the bearing bush 6 can be formed with recesses 19 and the seal 5 with projections 20. It can also be provided that the bearing bush 6 and the seal 5 respectively (preferably alternately) recesses 19 and projections 20 have. In the exemplary embodiment, the projections 20 / depressions 19 are each formed radially on the outside of the end face of the bearing bush 6 or the seal 5. The projections 20 on the bearing bush 6 and the recesses 19 in the seal 5 are arranged annularly or on a circular path.

It is advantageous to form the bearing bush 6 and the seal 5 in one piece. Preferably, the bearing bush 6 and the seal in one piece of a plastic, preferably be prepared by injection molding. It is preferably provided to inject the bearing bush 6 and the seal 5 as a part in the two-component method. The seal 5 and the bearing bushing 6 are thus formed as a part (ie integrally) and also mounted as a part. For clarity and understanding, the seal 5 and the bearing bush 6 are shown in two parts in the exemplary embodiment.

The holding cap 4 according to the invention has an interior 9 for receiving the seal 5 and the bearing bush 6. The retaining cap 4 has an inner diameter that matches the outer diameter of the end of the receiving tube

2 is adapted such that the retaining cap 4 is at least approximately flush with the end of the outer tube 2 attachable. Furthermore, the retaining cap 4 has a peripheral wall 10, which is provided in the exemplary embodiment with four locking elements 11.

The retaining cap 4 further has a front annular surface 12, which extends radially inwards starting from the circumferential wall 10 and the inner tube

Surrounds 3 at a distance. On the inside of the annular surface 12, the seal 5 is applied. The annular surface 12 of the retaining cap 4 surrounds the inner tube 3 such that an annular gap for the wiper lip 7 of the seal 5 remains. This is particularly well from Fig. 2 can be seen.

The retaining cap 4 is shown in detail in Figures 4 to 7.

As is apparent in particular from FIGS. 1 and 2, a receptacle 13 for the at least one latching element 11, in the exemplary embodiment for the four latching elements 11, is provided on the outer circumference of the outer tube 2. The receptacle 13 and the latching elements 11 are arranged to one another such that after the latching of the latching elements 11 into the receptacle 13, a gap 14 between the inner tube 3 and the outer tube 2 is closed.

The receptacle 13 is formed in the embodiment as a ring around the outer circumference of the outer tube 2 circumferential narrow groove. The seal 5 or the sealing bead 5 a is axially prestressed between an end face of the outer tube 2 and the inner side of the annular surface 12 of the retaining cap 4. The sealing takes place by axial pressing of the seal 5 or the sealing bead 5a (see FIG. 1a) against the end face of the outer tube 2.

As is apparent in particular from FIGS. 2 and 3, the circumferential groove 13 in the outer circumference of the outer tube 2 has a bevel 15 for engaging an underside of the detent element 11 and a substantially radially extending detent edge 16 on which the end face of the front end of Locking lug 11 can engage securely.

An assembly of the retaining cap 4 on the end of the outer tube 2 is carried out such that initially the bearing bush 6 with seal 5 (one-piece) is inserted into the intermediate space 14 between the outer tube 2 and the inner tube 3. Finally, the retaining cap 4 is pushed onto the inner tube 3 and attached to the outer circumference of the outer tube 2, that the locking elements 11 engage securely in the circumferential groove 13. The wiper lip 7 of the seal 5 protrudes into the annular gap between the annular surface 12 and the inner tube. 3

The seal 5 thus takes place between the end face of the outer tube 2 and the sealing bead 5 a and between the outer periphery of the inner tube 3 and the wiper lip. 7

As apparent from FIGS. 1 and 2, the bearing bush 6 has a circumferential enlargement 21 at its end facing the seal 5. The outer circumference formed by the circumferential enlargement is greater than the inner circumference of the outer tube 2, so that the bearing bush with the circumferential enlargement 21 bears against the end face of the outer tube 2. The circumferential enlargement 21 thus assumes the function of the axial fixation, so that the penetration depth of the bearing bush 6 is limited or defined in the outer tube 2.

A circumferential enlargement is also particularly suitable when the bearing bush 6 and the seal 5 are formed in one piece or in one piece. 4 shows a rear view of the holding cap 4. The peripheral wall 10 of the holding cap 4 has a substantially circular outer circumference with circumferential partial bulges 17. Overall, eight bulges 17 are provided in the embodiment. The bulges 17 can be divided into two groups, each with four identical bulges. A first group of bulges 17 'respectively surrounds the region of the latching lugs 11, while a second group of bulges 17 "is arranged in an intermediate space between two latching elements 11.

Due to the bulges 17 ', 17 ", the retaining cap 4 adapts advantageously to the outer circumference of a steering shaft 1. Steering shafts can preferably be produced with an outer circumference having bulges 17', 17". As is apparent from Fig. 2, the inside of the peripheral wall 10 of the retaining cap 4 rests against the outer periphery of the outer tube 2.

In the exemplary embodiment, the holding cap 4 has an inner diameter of 30 mm to 50 mm, preferably 38 mm.

The axial length of the peripheral wall 10 of the retaining cap 4 has in the exemplary embodiment 10 mm to 20 mm, preferably 15 mm.

The wall thickness of the retaining cap 4 may be in the embodiment 0.5 mm to 2 mm, preferably 1 mm.

As is apparent in particular from a combination of Figures 4 to 7, the locking elements 11 are formed in the embodiment as locking tabs. The locking tabs 11 extend from the peripheral wall 10 of the retaining cap 4 against the mounting direction. The free end of the locking tabs 11 is bent in the direction of the interior 9 (see in particular in Fig. 7). The retaining cap 4 has recesses 18, in each of which a locking tab 11 is formed. The recesses 18 may preferably have an extension of 8 mm to 15 mm, preferably 12 mm, in the circumferential direction of the peripheral wall 10 and 3 mm to 8 mm, preferably 5 mm, in the axial direction. The locking tab 11 has in the exemplary embodiment an extent of 4 mm to 12 mm, preferably 8 mm, in the circumferential direction and a length of 2 mm to 5 mm, preferably 3 mm, in the axial direction. With these dimensions, the locking tabs 11 protrude into the recess 18.

The annular surface 12 may preferably be designed such that the opening in the annular surface 12, through which the inner tube 3 can be inserted, has a diameter of 25 mm to 35 mm, preferably 29 mm.

As is apparent from Figures 4 to 7, the locking tabs 11 are evenly distributed around the circumference of the retaining cap 4, resulting in a particularly stable connection with the recess 13 in the outer periphery of the outer tube 2.

In the exemplary embodiment is provided to form the retaining cap 4 made of metal. Preferably, the retaining cap 4 may be formed of a coated sheet metal part or of stainless steel or another metal having a corrosion protection and a high strength.

LIST OF REFERENCE NUMBERS

1 steering shaft

2 outer tubes

3 inner tube

4 retaining cap

5 seal

5a sealing bead

6 bearing bush

7 wiper lip

8 punctures

9 interior

10 peripheral wall

11 locking element

12 ring surface

13 recording, groove

14 gap

15 slope

16 locking edge

17 bulge

18 recess

19 deepening

20 advantage

21 Circumference enlargement

Claims

claims 1. Telescopic steering shaft with an outer tube, in which an inner tube is guided axially displaceable, and with a seal which closes at the end of the outer tube, a gap between the inner tube and the outer tube, characterized by 1.1 a holding cap (4) with a) an inner space (9) for receiving the seal (5) b) an inner diameter which is adapted to the outer diameter of the end of the outer tube (2) such that the retaining cap (4) at least approximately flush c) a peripheral wall (10) having at least one latching element (11), and d) a front annular surface (12) extending radially inwardly from the peripheral wall (10) extends and encloses the inner tube (3) at a distance and on the inside of which the seal (5) rests; and 1.2 at least one receptacle (13) on the outer circumference of the outer tube (2) for the at least one latching element (11), wherein the receptacle (13) and the latching element (11) are arranged to each other such that after the latching element (11) in the receptacle (13) of the intermediate space (14) between the inner tube (2) and the outer tube (2) is closed. 2. Steering shaft according to claim 1, characterized in that the seal (5) on the retaining cap (4) is formed. 3. Steering shaft according to claim 1, characterized in that the seal (5) as of the holding cap (4) is formed separate part and the seal (5) after the engagement of the locking element (11) in the receptacle (13) sealingly between the Outer tube (2) and the retaining cap (4) is arranged. 4. Steering shaft according to claim 3, characterized in that the seal (5) between an end face of the outer tube (2) and the retaining cap (4) is axially biased. 5. Steering shaft according to one of claims 1 to 4, characterized in that two or more radially evenly distributed around the circumference of the peripheral wall locking elements (11) and adapted receptacles (13) in the outer circumference of the outer tube (2) are provided. 6. Steering shaft according to one of claims 1 to 5, characterized in that the latching elements (11) are designed as latching lugs or latching tabs extending from the peripheral wall (10) of the retaining cap against the mounting direction and the free end in the direction of the interior (9) is bent inwards. 7. Steering shaft according to claim 6, characterized in that the retaining cap (4) recesses (18), in which in each case the latching lugs (11) or locking tabs are formed. 8. Steering shaft according to one of claims 1 to 7, characterized in that the receptacle (13) on the outer circumference of the outer tube (2) is designed as a circumferential groove, as a recess or as a notch. 9. Steering shaft according to claim 8, characterized in that the groove, the recess or the notch (13) has a bevel (15) as an abutment for an underside of the latching lug (11) or latching tab and a substantially radially extending latching edge (16) , on which the front side of the front end of the latching lug (11) or the latching tab can be latched securely. 10. Steering shaft according to one of claims 1 to 9, characterized in that the seal (5) has a circumferential wiper lip (7) which bears against the inner tube (3). 11. Steering shaft according to claim 10, characterized in that the annular surface (12) of the retaining cap (4) surrounds the inner tube (3) such that a narrow annular gap for the wiper lip (7) remains. 12. Steering shaft according to one of claims 1 to 11, characterized in that the seal (5) has a peripheral sealing bead (5 a), which in the installed state adjacent to the end face of the outer tube (2). 13. Steering shaft according to one of claims 1 to 12, characterized in that in the interior (9) of the retaining cap (4) formed as a separate part bearing bush (6) is added. 14. Steering shaft according to one of claims 1 to 12, characterized in that the seal (5) is formed integrally with a bearing bush (6). 15. Steering shaft according to one of claims 1 to 14, characterized in that the peripheral wall (10) of the retaining cap (4) is formed substantially circular and circumferential, deviating from the circular shape partial bulges (17). 16. Steering shaft according to one of claims 1 to 15, characterized in that the holding cap (4) made of metal, preferably as a coated sheet metal part or stainless steel, is formed.