METHOD FOR MOUNTING A SHAFT, BEARING ARRANGEMENT FOR A

SHAFT AND WINDSCREEN WIPER DRIVE

PRIOR ART

The invention relates to a method for mounting a shaft according to the introductory clause of Claim 1. The invention further relates to a bearing arrangement for a shaft and a windscreen wiper drive with a bearing arrangement .

A method for mounting a shaft according to the introductory clause of Claim 1 is known from DE 10 2005 019 501 Al of the applicant. In the method described there, in a windscreen wiper system an eccentric bush is used which, in a state in which it is only inserted with a partial length into a receiving bore of a housing, is rotated in its angular position for adapting a distance between a toothing of the worm shaft and a toothing of a toothed wheel meshing therewith. As soon as the desired angular position of the eccentric bush or respectively the desired distance is reached, the eccentric bush is inserted completely by application of an axial force into the receiving bore, wherein between the outer periphery of the eccentric bush and the receiving bore of the housing a press fit is formed, which anchors the eccentric bush in a torque-proof manner in its angular position in the housing.

It has been found in practice that under particular geometrical conditions, in spite of the press fit a rotation of the eccentric bush can still occur, with a change to the above-mentioned distance, related thereto, during the operation of the windscreen wiper system. Attempts could indeed be made, through a corresponding configuration of the external diameter of the eccentric bush or respectively the dimensioning of the internal diameter of the receiving bore in the housing, to increase the holding force in the press connection, but thereby at the same time the necessary axial force for pressing the eccentric bush into the receiving opening is increased in an undesirable manner.

Furthermore, from DE 198 21 079 Al an electric drive unit is known in which an eccentric bush is fastened in a housing via a detent connection. This detent connection is formed as soon as the eccentric bush has reached its correct angular position to the housing and the eccentric bush is pressed in axial direction into the receiving bore, wherein the detent connection is formed. However, a press connection between the eccentric bush and the receiving bore in the housing is not provided.

DISCLOSURE OF THE INVENTION

Proceeding from the presented prior art, the invention is based on the problem of further developing a method for mounting a shaft according to the introductory clause of Claim 1, such that in the axial final position of the eccentric bush in the bearing housing, a secure or respectively torsion-proof arrangement of the eccentric bush is achieved, wherein the necessary axial forces for pressing the eccentric bush into the receiving opening of the bearing housing are to be relatively small. This problem is solved in a method for bearing a shaft with the features of Claim 1. The invention is based here on the idea, through an additional torque-proof connection between the bearing housing and the eccentric bush, which is formed only in the final position of the eccentric bush, of forming a torque-proof arrangement in the bearing housing in the final position of the eccentric bush, which additionally intensifies or respectively assists the press connection between the eccentric bush and the bearing housing . Advantageous further developments of the method for mounting a shaft according to the invention are indicated in the subclaims. All combinations of at least two of features disclosed in the claims, the description and/or the figures fall within the scope of the invention.

Preferably, provision is made that a form- or force-fitting connection is formed as additional connection between the eccentric bush and the bearing housing. Thereby, it is possible in particular to dispense with the use of additional mounting tools, so that a windscreen wiper drive produced by the method according to the invention is able to be produced at a particularly favourable cost.

The invention also comprises a bearing arrangement for a shaft with the features of the independent claim. Provision is made here that between the eccentric bush and the bearing housing in the axial final position of the eccentric bush an additional torque-proof connection is formed in addition to the press fit.

In a preferred structural implementation of the invention, it is proposed that the connection comprises a toothing profile. Through such a toothing profile, with relatively small pressing-in depths relatively great holding forces can be achieved, which prevent a torsion of the eccentric bush in the bearing housing.

The distribution profile can be formed for example as a knurling profile or as a polyhedron. Such toothing profiles can be produced relatively simply and at a favourable cost and allow a secure fastening of the eccentric bush in the bearing housing by application of a corresponding force for the formation of the connection.

It is furthermore preferred if the toothing profile is formed on an external circumference of the eccentric bush. Through the arrangement on the external circumference of the eccentric bush, the torque which is to be transferred or respectively applied, which is necessary for overcoming the torque-proof connection, is maximized here.

Further advantages, features and details of the invention will be apparent from the following description of preferred example embodiments and with the aid of the drawings, which show in:

Fig. 1 an exploded illustration of the components of a windscreen wiper drive, a side view of an eccentric bush having a knurling profile, a top view onto the eccentric bush according to Fig. 2, a side view of an eccentric bush, modified with respect to Fig. 2, using a polyhedron, a longitudinal section through a mounted windscreen wiper drive during the setting position of the eccentric bush, a detail of Fig. 5 on an enlarged scale, likewise in longitudinal section, and Fig. 7 the detail according to Fig. 6 in the axial final position of the eccentric bush. Identical components or respectively components having the same function are given the same reference numbers in the figures .

In Fig. 1 the individual components of a windscreen wiper drive 10 are illustrated. The windscreen wiper drive 10 serves for driving at least one windscreen wiper, not illustrated in the figures, in a motor vehicle.

The windscreen wiper drive 10 comprises a motor casing 11, in which an armature 12 is arranged, which together with other components which are not illustrated forms a drive motor of the windscreen wiper drive 10. The armature 12 has a drive shaft 13 which has a toothing in the form of a drive worm 14. The motor casing 11 is fastened at the one, open side of a gear housing 15 in a known manner, e.g. by screw connections. Here, the drive shaft 13 projects with the drive worm 14 into the gear housing 15, wherein the end 16 of the drive shaft 13, facing the gear housing 15, is preferably additionally mounted in the gear housing 15.

In the gear housing 15 in addition an output shaft 18 is mounted, the one end of which in the mounted state projects out from the gear housing 15 and has a drive toothing 19, which cooperates seamlessly with a counter-element, which is not illustrated, in particular a windscreen wiper mechanism, so that a torque which is introduced via the output shaft 18 and the drive toothing 19 can be used for moving the windscreen wiper.

The output shaft 18 is connected in a torque-proof manner with a toothed wheel 20 having a relatively large diameter, on the external periphery of which a toothing 21 is formed, which cooperates with the toothing of the drive worm 14 of the drive shaft 13. In order to set the axial distance a between the output shaft 18 and the drive shaft 13, so that the toothing 21 cooperates or respectively meshes in the desired region with the drive worm 14, an eccentric bush 25 is provided, in which the drive shaft 18 is rotatably mounted (Fig. 5) . The eccentric bush 25 is inserted here into a receiving opening 26 of a dome-like extension 27 of the gear housing 15.

On the side facing the toothed wheel 20, the eccentric bush 25 has a first region 28 with a relatively small external diameter, adjoining which on the side facing away from the toothed wheel 20 there is a second region 29 with an enlarged external diameter compared with the first region 28. The two regions 28, 29 of the eccentric bush 25 cooperate with sections 31, 32 of different diameter in the receiving opening 26, wherein a through-bore 33 in the eccentric bush 25, which serves for receiving or respectively mounting the output shaft 18, is arranged slightly eccentrically with respect to the external periphery of the two regions 28, 29. In addition, through a corresponding geometric dimensioning of the external diameter of the two regions 28, 29 or respectively of the internal diameters of the sections 31, 32 between the eccentric bush 25 and the receiving opening 26 a press fit is formed. The press fit brings about a fixed arrangement of the eccentric bush 25 in the receiving opening 26 such that an axial inserting or respectively pressing in of the eccentric bush 25 in the direction of the arrow 35 and a twisting of the eccentric bush 25 in its longitudinal axis in accordance with the arrow 36 is only made possible by application of a correspondingly great axial force or respectively of a correspondingly great torque.

As can be seen by viewing Fig. 2 and 3 together, the eccentric bush 25 has a collar 38, which in the example embodiment has attachment eyes 39, 40 for the application of an adjusting tool. By means of the adjusting tool, which is not illustrated, the eccentric bush 25 can be twisted in its angular position here in accordance with the direction of the arrow 36.

According to the invention, provision is made that the eccentric bush 25 has an additional connection 41 in the form of a form- or force-fitting connection 41. In the illustrated example embodiment according to Fig. 2, the connection 41 has a toothing profile 42. The toothing profile 42 is formed directly beneath the collar 38 on the external periphery of the second region 29 of the eccentric bush 25, wherein the external diameter of the toothing profile 42 projects over the external diameter of the second region 29. The toothing profile 42 is constructed as a knurling profile and has a plurality of elevations 43 arranged in longitudinal direction of the eccentric bush 25. In the modified eccentric bush 25a, illustrated in Fig. 4, the toothing profile 42a is constructed in the form of a polyhedron 44.

The toothing profile 42, 42a cooperates with a stepped bore section 45, illustrated in Fig. 6 and 7, in the receiving opening 26. The dimensioning of the diameter of the stepped bore section 45 here is such that on pressing the eccentric bush 25, 25a into the receiving opening 26 or respectively the stepped bore section 45, the toothing profile 42, 42a plastically deforms the material of the gear housing 15 or respectively of the stepped bore section 45, or respectively the toothing 43 (or respectively the polyhedron 44) buries itself into the material of the gear housing 15 or respectively of the stepped bore section 45, so that the additional torque-proof connection 41 is formed between the eccentric bush 25, 25a and the gear housing 15, which intensifies the press fit between the eccentric bush 25, 25a and the receiving opening 26 in the area of the regions 28, 29. The mounting of the eccentric bush 25, 25a in the gear housing 15 is now explained in further detail with the aid of Fig. 5 to 7: In the setting position of the eccentric bush 25, 25a illustrated in Fig. 5 and 6, the eccentric bush 25, 25a is only pressed into the receiving opening 26 with a partial length, i.e. not completely up to the collar 38. In this position, the press connection or respectively press fit is already formed between the eccentric bush 25, 25a and the receiving opening 26, so that by means of the already mentioned adjusting tool, by application of a torque onto the eccentric bush 25, 25a, the angular position can be adjusted in order to influence the distance a in the desired manner. As soon as the angular position of the eccentric bush 25, 25a has reached its desired position, by application of an additional axial force in the direction of the arrow 35 the eccentric bush 25, 25a is pressed into its axial final position into the receiving opening 26. Here, the toothing profile 42, 42a of the eccentric bush 25, 25a arrives in the desired manner into operative connection with the stepped bore section 45, so that in the desired manner the torque which is to be applied for twisting the eccentric bush 25, 25a is increased such that such a torque can be ruled out during the operation of the windscreen wiper drive 10. The windscreen wiper drive 10 described so far, or respectively its components, can be altered or respectively modified in a variety of ways, without departing from the idea of the invention. The latter consists, in addition to the press connection known from the prior art or respectively the known press fit between the eccentric bush 25, 25a and the receiving opening 26 in the gear housing 15, of forming an additional torque-proof connection 41 in the form of a form- or respectively force-fitting connection 41, in particular by means of a toothing 43. Thus it is conceivable, for example, to form the toothing 43 in the receiving opening 26, or in another section of the eccentric bush 25, 25a or respectively the receiving opening 26.

LIST OF REFERENCE NUMBERS

10 windscreen wiper drive

11 motor casing

12 armature

13 drive shaft

14 drive worm

15 gear housing

16 end

18 output shaft

19 drive toothing

20 toothed wheel

21 toothing

25, 25a eccentric bush

26 receiving opening

27 extension

28 first region

29 second region

31 section

32 section

33 through-bore

35, 35a arrow

36 arrow

38 collar

39 attachment eye

40 attachment eye

41 additional connection

42, 42a toothing profile

43 elevation

44 polyhedron

45 stepped bore section