WO1998016413A1

WO1998016413A1 - Windscreen wiper bearing

Info

Publication number: WO1998016413A1
Application number: PCT/DE1997/001809
Authority: WO
Inventors: Kurt Muehlpforte; Claus Fleischer
Original assignee: Robert Bosch Gmbh
Priority date: 1996-10-12
Filing date: 1997-08-22
Publication date: 1998-04-23
Also published as: DE19642184A1

Abstract

The invention concerns a windscreen wiper bearing (10) for holding the wiper shaft of a windscreen wiper device for motor vehicle windscreens, with a bearing housing (12) which has a through-opening (16) for the shaft, and a bearing bush (14) which is disposed in the through-opening (16) and holds the shaft. According to the invention, the bearing bush (14) is a part made of plastics injected into the through-opening (16) in the bearing housing (12).

Description

Seisibenwiseherlager

The invention relates to a windshield wiper bearing for receiving a wiper shaft of a windshield wiper device for windshields of motor vehicles, with the features mentioned in the preamble of claim 1.

State of the art

Windshield wiper bearings, hereinafter called bearings, of the generic type are known. For example, windshield wiper devices for windshields of motor vehicles have a holder for the windshield wiper device, which is referred to as a holding plate and has a bearing for a wiper shaft arranged on at least one end. The bearing is formed by a bearing housing which is non-positively connected to the holding plate. As is known, the bearing housings are made of die-cast, for example aluminum or zinc die-cast. The bearing housings have a fastener for the holding plate and on the other hand a fastening means for fastening the entire windshield wiper device to a body part of the motor vehicle. In addition, the bearing housing has a through opening through which the wiper shaft is guided. At least one bearing bush is arranged within the through opening, which serves to guide the wiper shaft. The bearing bushes are usually designed as sintered bushes, which are pressed into the through openings of the bearing housing. In the known bearings it is disadvantageous that both the through opening of the bearing housing and the bearing bush have to be manufactured with high accuracy in order to ensure a defined pressing of the bearing bushes and thus a secure hold.

Advantages of the invention

The bearing according to the invention with the features mentioned in claim 1 offers the advantage that it is simple in construction and can be produced with simple process steps. Due to the fact that the bearing bush is a plastic part injected into the bearing housing, no high-precision tolerance requirements need to be imposed on the manufacture of the bearing housing, in particular on the formation of the through opening of the bearing housing, since any existing manufacturing tolerances are compensated for by the injected plastic part. The injection of the plastic part into the bearing housing is simple by means of known techniques to be mastered in a manner suitable for mass production. The process of pressing in the bearing bush is thus completely eliminated. In addition, very precise manufacturing of the bearing bush is possible by means of the spraying technique, so that a subsequent calibration of the bearing bush is also eliminated.

In an advantageous embodiment of the invention it is provided that the through opening of the bearing housing, which is advantageously made as a die-cast part, has at least one axially extending groove which is filled by the plastic of the bearing bush. In this way, a rotation lock for the bearing bush is very advantageously achieved. Since the groove is filled with plastic during the injection molding process in the manufacture of the plastic bearing bush, there are also no high tolerance requirements for the manufacture of the groove. In particular, it is advantageous that the groove can be designed as a dovetail groove, so that, in addition to the anti-rotation device, the bearing bush is also prevented from shrinking. Since the injection of the plastic is known to take place in the plasticized state, that is to say in the heated state, the dovetail groove achieves a radial undercut of the bearing bush, which essentially precludes radial shrinkage of the plastic during cooling. As a result, the running surface of the bearing bush for the shaft can be manufactured with high accuracy. It is also advantageous if the bearing surface of the bearing bush has at least one essentially axially extending groove. This makes it very advantageously possible to use this at least one groove as a lubricant groove, so that there is a lubricant reservoir for the shaft guided in the bearing bush.

Further advantageous embodiments of the invention result from the other features mentioned in the subclaims.

drawings

The invention is explained in more detail below in exemplary embodiments with reference to the associated drawings. Show it:

1 shows a longitudinal section through the bearing according to the invention;

Figure 2 is a sectional view of the bearing;

FIG. 3 shows a partial view of a first end collar;

Figure 4 is a partial view of a second frontal collar

Figures sectional views of the 5 to 6 bearing according to the invention in further embodiments. Description of the execution examples

FIG. 1 shows a bearing 10. The bearing 10 comprises a bearing housing 12 and a bearing bush 14 arranged inside the bearing housing 12. The bearing housing 12 has a through opening 16 for receiving the bearing bush 14. Bearings 10 of the type shown here can be used, for example, in windshield wiper devices for wiping windows on motor vehicles. In this case, the bearing 10 has fastening means (not shown in the figures) for fastening to a holding plate (also not shown) and fastening means for fastening the wiper device to body parts of motor vehicles. In the context of the present description, however, only the actual storage area of the bearing 10 is to be explained in more detail.

The bearing housing 12 consists of a cast part, for example an aluminum or zinc die-cast part, which can be produced by means of known process steps. The bearing housing 12 is - as seen in the axial direction of the bearing housing - so long that a shaft, not shown here, can be securely received and held.

In the further description of the bearing 10, reference is also made to the enlarged representations in FIGS. 2, 3 and 4, wherein FIG. 2 shows a cross section through the bearing 10 and FIGS. 3 and 4 each show an enlarged section of bundles yet to be explained. The passage opening 16 of the bearing housing 12 is essentially circular. Grooves 20 extending radially outward are introduced into a lateral surface 18 of the through opening 16. The bearing housing 12 has at least one groove 20. In the exemplary embodiment shown, a total of five grooves 20 are provided, which are arranged over the circumference of the lateral surface 18. The grooves 20 are designed as dovetail grooves 22, so that there is a radial undercut 24. The grooves 20 are produced with the production of the bearing housing 12 in terms of production technology, by using appropriately designed molds during die casting of the bearing housing 12. The depth of the grooves 20 is selected so that on the one hand the strength of the entire bearing housing 12 is ensured and on the other hand webs 26 remaining between the grooves 20 have sufficient strength.

The bearing bush 14 is injected into the bearing housing 12 as a plastic injection-molded part. For this purpose, an appropriately designed core of an injection molding tool can be introduced into the through opening 16 of the bearing housing 12 such that an annular gap remains between the core and the bearing housing 12. This annular gap is sprayed with plasticized plastic, which results in the bearing bush 14 after cooling. By injecting the bearing bush 14 into the bearing housing 12, relatively low tolerance requirements are imposed on the manufacture of the bearing housing 12, in particular on the dimensional accuracy of the through opening 16 and the grooves 20 set, since any manufacturing inaccuracies during the injection of the bearing bush 14 are compensated. A tread 28, which serves to receive a shaft, for example a wiper shaft, is predetermined by the shape or the outer surface of the core of the injection mold and can thus be produced with high precision.

The dovetail grooves 22 ensure, on the one hand, that the bearing bush 14 is secure against twisting and, on the other hand, prevent shrinkage when the injected plasticized plastic cools. This ensures the dimensional accuracy of the tread 28 with high accuracy, since subsequent shrinkage processes can have practically no influence on the geometry of the tread 28. The shrinkage hindrance further facilitates removal of the core of the injection mold after the plastic has cooled.

The running surface 28 of the bearing bush 14 has essentially axially extending grooves 30 over its circumference, preferably distributed symmetrically. These grooves 30 form lubricant grooves and serve to receive lubricants, which reduces the frictional resistance of a shaft guided through the bearing 10 on the running surface 28 of the bearing bush 14.

Due to the design of the dovetail grooves 22, there are quasi webs 32 of the bearing bush 14 which engage in a form-fitting manner in the dovetail grooves 22. The dovetail grooves 22 extend not over the entire axial length of the bearing housing 12, so that the webs 32 of the bearing bush 14 engaging in the dovetail grooves 22 prevent an axial displacement of the bearing bush 14 within the bearing housing 12 in addition to an anti-rotation device.

When the bearing bush 14 is injected, a collar 38 or 40 of the bearing bush 14 is injection molded onto an axial end face 34 shown in FIG. 1 above and an axial end face 36 shown below in FIG. 1. The structure of the end faces 34 and 36 or the bundles 38 and 40 is explained in more detail with reference to FIGS. 3 and 4. 3 shows the end face 34 with the collar 38 and in FIG. 4 the end face 36 with the collar 40.

It is clear from FIG. 3 that an annular bead 42 arises from the end face 34 of the bearing housing 12. The bearing housing 12 merges into an annular shoulder 44 in the annular bead 42. The annular bead 42 is arranged at a distance from an outer surface 46 of the bearing housing 12. The transitions from the passage opening 16 to the ring step 44 and from this to the ring bead 42 are each rounded off. Axial boundary surfaces 48 and 50 of the annular bead 42 are tapered, so that the annular bead 42 is quasi tapered. At their apex 52, the boundary surfaces 48 and 50 merge into one another over a radius. The configuration of the axial end face 34 described here ensures that the molded collar 38 of the bearing bush 14 engages behind the bead 42 in a hook-like manner. This on the one hand ensures radial fixing of the bearing bush 14 in the bearing housing 12. On the other hand, by reaching behind the annular bead 42 through the collar 38, the bushing 14 is prevented from shrinking during its cooling, both in the axial and in the radial direction, so that, on the one hand, the dimensional accuracy of the running surface 28 of the bearing bush 14 is ensured at its axial end. On the other hand, an axial contact surface 54 with high dimensional accuracy can thus be achieved by the collar 38. The axial contact surface 54 can very advantageously serve to support, that is, to absorb axial forces from parts held by means of the shaft guided through the bearing 10, for example wiper arms of a wiper device for motor vehicles.

The collar 38 forms at the same time an installation space designed as an annular space 56 for a sealant. The annular space 56 is delimited by a radially running surface 58 which arises from the running surface 28 and the collar 38. A sealing ring, for example, can be inserted into the resulting annular space 56, which prevents the ingress of contaminants into the bearing 10, in particular between the shaft and the bearing bush 14.

As FIG. 4 shows, the axial end face 36 likewise has an annular bead 60, the limitation of which surfaces 62 and 64 also run conically and merge into one another over a radius at the apex 66 of the annular bead 60. The passage opening 16 of the bearing housing 12 merges into the end face 36 via an annular surface 68 which widens conically outwards. The annular bead 60 is arranged such that the collar 40 engages behind it in a hook-like manner. The collar 40 forms an axial contact surface 70 against which a drive means, for example a crank linkage of a wiper drive, can rest.

The design of the annular beads 42 and 60 or the collars 38 and 40, in particular the conical surfaces or roundings, ensures that the bushing 14 is prevented from shrinking on the one hand and that axial forces acting on the contact surfaces 54 and 70 on the other hand te can be derived particularly well into the bearing housing 12.

FIGS. 5 to 6 show further variants of the bearing 10. The same parts as in the previous figures are provided with the same reference numerals and are not explained again. Differences with regard to the structure exist above all in the design of the end faces 34 and 36 or the bundles 38 and 40. According to the exemplary embodiment shown in FIG. 5, it is provided that the end faces 34 and 36 each have an annular bead 42 or 60, seen in cross section . This will make manufacturing the mold for the bearing housing 12 simplified. Such embodiments can be used if the axial forces introduced via the axial contact surfaces 54 and 70 are relatively small.

According to the exemplary embodiment shown in FIG. 6, the formation of the annular beads 42 or 60 was completely dispensed with, so that the collar 38 or collar 40 lies smoothly on the axial end faces 34 or 36 of the bearing housing 12. As a result, an even more simplified production of a shape for the bearing housing 12 is achieved.

If the bearing bush is designed with an axial collar, the axial shrinkage hindrance on the opposite side can, if necessary, also be realized by means of appropriately designed undercuts, steps or the like or on the ends of the webs 26.

The presented and stressed wiper bearings can also be used for other purposes. The main advantages such as simple, inexpensive production or the high dimensional accuracy of the bearings are also taken over.

Claims

claims

1. Windshield wiper bearing for receiving a wiper shaft of a windshield wiper device for windshields of motor vehicles, with a bearing housing which has a through opening for the shaft and a bearing bush arranged in the through opening and receiving the shaft, characterized in that the bearing bush (14) is a in the through opening

(16) of the bearing housing (12) is injected plastic part.

2. Windshield wiper bearing according to claim 1, characterized in that the through opening (16) of the bearing housing (12) has at least one groove (20) extending in the axial direction of the bearing housing (20) of at least one web (26) of the bearing bush (14). is filled out.

3. Wiper bearing according to one of the preceding claims, characterized in that the groove (20) is designed as a dovetail groove (22).

4. Windscreen wiper bearing according to one of the preceding claims, characterized in that the bearing bush (14) has at least one, essentially axially extending groove (30) on its running surface (28).

5. Windscreen wiper bearing according to one of the preceding claims, characterized in that the bearing bush (14) overlaps the bearing housing (12) on at least one axial end face (34, 36) with a collar (38, 40).

6. Windscreen wiper bearing according to one of the preceding claims, characterized in that the collar (38, 40) forms an axial contact surface (54, 70) for a part mounted by means of the shaft.

7. Windscreen wiper bearing according to one of the preceding claims, characterized in that the bearing housing (12) on its axial end face (34, 36) has an annular bead (42, 60) which is encompassed by the bearing bush (14).

8. Windscreen wiper bearing according to one of the preceding claims, characterized in that the annular bead

(42, 60) has rounded edges.

9. Windscreen wiper bearing according to one of the preceding claims, characterized in that the axial boundary surfaces (48, 50, 62, 64) of the annular beads

(42, 60) taper.

10. Windscreen wiper bearing according to one of the preceding claims, characterized in that the end face (36) merges into the through opening (16) via a conically extending annular surface (68).

11. Windshield wiper bearing according to one of the preceding claims, characterized in that the end face (34) merges into the through opening (16) via an annular step (44).

12. Windscreen wiper bearing according to one of the preceding claims, characterized in that at least one collar (38, 40) of the bearing bush (14) forms an installation space (56) for a sealant.