GB1580385A

GB1580385A - Pivotal joints

Info

Publication number: GB1580385A
Application number: GB2143277A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1976-05-20
Filing date: 1977-05-20
Publication date: 1980-12-03
Also published as: DE2622437A1; FR2351826A1; IT1074517B; DE2622437C3; SE7705802L; FR2351826B1; DE2622437B2

Description

(54) IMPROVEMENTS IN OR RELATING TO PIVOTAL JOINTS (71) We, ROBERT BOSCH GMBH, a German Company, of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to pivotal joints and in particular, a pivotal joint for a wiper device for a screen of a motor vehicle.

A known type of wiper device for windscreens or headlamp covers has a driven wiper arm, on which is fixed one pivotal part of a pivotal joint whose pivoting axis is substantially perpendicular to the wiper plane, and a wiper blade resting on the windscreen held on another pivotal part of the joint, the one pivotal part engaging, by means of a journal pin, defining a pivoting axis, into a bearing bush of the other pivoting part.

Wiper devices constructed in this manner have the effect of increasing the wiper field because the wiper blade is swivelled when it runs against a stop lying preferably at the edge of the screen to be wiped. As the wiper blade returns, it swivels back owing to spring-loading into its starting position in which it lies parallel to the screen edge.

In a known wiper device of this type, the two pivotal parts are connected to one another by a screw disposed along the pivoting axis which passes through a bore in one pivotal part and which is held in a threaded bore in the other pivotal part. This method of securing the pivotal parts on one another is expensive in terms of manufacture and also takes a relatively long time to assemble, because the through bore and the threaded bore must be made and a fixing screw prepared. Moreover, a locking washer is also required to prevent the screw from working loose while the device is in operation.

According to the present invention there is provided a pivotal joint for a wiper device for a screen of a motor vehicle which joint comprises a first pivotal part adapted to receive a wiper blade and having a pivotal journal pin of circular cross section which is a snap-fit connection in a corresponding pivotal bearing bush formed in a second pivotal part, the snap-fit connection being provided by a cooperating annular projection and annular recess, the projection being formed on one pivotal part and the recess being formed in the other pivotal part, each pivotal part having a substantially axially extending swivel stop for limiting the pivotal displacement of the joint.

An advantage of the present invention is that it improves the known wiper device in such a manner that few parts are required to construct the pivotal joint thereby simplifying its assembly.

The snap-fit connection of the joint is enhanced when either the journal pin and its annular projection or the bearing bush or both are made from a resiliently deformable synthetic material. The two pivotal parts have only to be pushed together in the direction of the pivoting axis and are assembled by means of applied pressure sufficient to achieve the snap-fit.

Advantageously, one of the swivel stops may be in the form of a lug which projects from the face of one pivotal part facing the other pivotal part and which engages in an associated recessed portion in the other pivotal part. Preferably the recessed portion extends parallel to the pivoting axis.

The recessed portion may be an arc of a circle about the pivoting axis terminating in end walls arranged to limit the motion of the lug in the two pivotal directions.

The pivotal part having the recessed portion may have a second similar recessed portion formed on the opposite side of the said pivotal part for receiving the lug when the joint is assembled with the pivotal part having the lug turned through 1800.

In order to hold the joint, and thus also the wiper blade in a deposit position, within a defined position, one end of a torsion spring may be fixed on each of the two pivoting parts, said spring being prestressed and encircling the pivoting axis. In the return position of the wiper blade, one wiper blade end engages a stop so that the wiper blade is pivoted against the spring force in the joint so that it lies parallel to the screen edge in the return position of the wiper blade.

The invention will be further described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan of a wiper device according to the invention being used to wipe a headlamp cover plate; Fig. 2 is a partial section of the pivotal part connectible to the wiper arm; Fig. 3 is a section along the line III--III through the pivotal part ofFig. 2, Fig. 4 is the other pivotal part, partially in section; Fig. 5 is a section along the line V-V through the pivotal part of Fig. 4; and Fig. 6 is a section through the joint formed by the two pivotal parts.

A wiper device 10 shown in Fig. 1 is used to wipe a headlamp cover plate 11 of a motor vehicle and has a wiper arm 13 which is driven about a pendulum axis 12 in a pendulumlike manner. A pivotal joint 14 is arranged on the free end of the wiper arm 10 and is the means whereby a wiper blade 15 is connected to the wiper arm 13. In the illustrated deposit position, the wiper blade 15 lies parallel to and close to the edge of the head lamp cover plate 11 to be wiped.

The pivotal joint 14 has two pivotal parts which are shown in Figs. 2 to 6 and of which a first pivotal part 16 is connected to the wiper arm 13 (Fig. 6). A second pivotal part 17 is used to fix the wiper blade 15 and has for this purpose a slot-shaped holder 18 and a resiliently deflectable stop fork 19 which co-operates with corresponding opposite locking means of the wiper blade. The two pivotal parts 16 and 17 are made from a resilient synthetic material.

The first pivotal part 16 (Fig. 2) has formed in its body 20 a pivotal bearing bush 21 with which a pivotal journal pin 22 of the second pivotal part 17 is a snap-fit connection. So that the two pivotal parts 16 and 17 in their assembled state (Fig. 6) are snap-fitted to one another, the journal pin 22 has an annular collar 23 which, in the assembled state (Fig. 6), is located in an annular groove 24 in the bearing bush 21.

To assemble the joint 14, the journal pin 22 of the second pivotal part 17 is urged into the bearing bush 21 of the first pivotal part 16.

In so doing, the annular collar 23 of the journal pin 22 and the bearing bush 21 are slightly deformed so that the annular collar 23 can lock into the annular groove 24 (Fig.

6) with the result that the two pivotal parts 16 and 17 are snap-fitted connected to one another. To improve the deformability of the annular collar 23 or of the journal pin 22, the latter may alternatively be provided with a central bore (not shown).

The face 25 of the first pivotal part 16 abutting the second pivotal part 17 has a lug 26 which projects from this face 25 and engages in a corresponding recessed portion 27 in the second pivotal part 17. The recessed portion 27 in the second pivotal part 17 extends coaxially with the journal pin 22.

The side surfaces 28 of the lug 26 form swivel stops which co-operate with the two end edges 29 of the recessed portion 27 lying in a swivel direction. The arc length of the recessed portion 27 is chosen, allowing for the width of the lug 26, so that the swivel angle required between the two pivoting parts 16 and 17 is attained. The pivotal joint also has a torsion spring 30 which, in the assembled state (Fig. 6), surrounds the journal pin 22 with initial stress, one end 31 of the spring being fixed in the first pivotal part 16 and the other end 32 in the second pivotal part 17. The torsion spring 30 lies in a chamber 33 formed by a stepped section 34 in the first pivotal part 16 and by a circular groove 35 in the second pivotal part 17. Extending from the stepped section 34 of the first pivotal part 16 is a short groove 36 which is used to hold one end 31 of the torsion spring. The other end 32 of the torsion spring is bent into a claw shape and is fixed in an axially extending bore 37 disposed in the base of the circular groove 35 (Fig. 5) of the second pivotal part 17.

Depending upon the winding direction and the initial stress of the torsion spring 30, one face 28 of the lug 26 lies adjacent to one of the two end edges 29 of the recessed portion 27.

In one such position, the wiper blade 15 forms an angle a with the free end of the wiper arm 13 (Fig. 1) and it extends parallel to the screen edge which extends in the region of the wiper blade return position.

When the wiper blade 15 moves back from the reversing point shown by broken lines in Fig. 1 into its deposit position, at first the angle a remains until one end of the wiper blade 15 hits against a stop 38 with the result that the wiper blade 15 is swivelled by the pivoting joint 14 in such a manner that in the deposit position it extends parallel to the free end of the wiper arm 13 and therefore parallel to the other screen edge.

So that the first pivotal part 16 may be easily connected to the wiper arm 13, the body 20 of the first pivotal part 16 has a lateral extension 39 having an insertion channel 40 (Fig. 6) into which a springloaded tongue 41 of the channel wall projects.

When the wiper arm 13 is inserted in the direction of the arrow 42 into the channel 40, the tongue 41 is deflected resiliently downwards until it can spring back into an opening 43 in the wiper arm end thereby securing the first pivotal part 16 to the wiper arm 13.

In order to offset the swivel range of the second pivotal part 17 selectively relative to the first pivotal part 16, the second pivotal part 17 has a second recessed portion 44 which is disposed in a mirror-image fashion relative to the first recessed portion 27 and whose end edges 45 may likewise co-operate with the side surfaces of the lug 26 when the two pivotal parts 16 and 17 are correspondingly assembled i.e. when part 16 has been turned through 1800. In this case, naturally, a torsion spring wound in the opposite direction to the above-described embodiment must be used, one end 31 of which then being fixed in a second groove 46 disposed in a mirror-image fashion relative to the groove 36 (Fig. 2).

WHAT WE CLAIM IS: 1. A pivotal joint for a wiper device for a screen of a motor vehicle which joint comprises a first pivotal part adapted to receive a wiper blade and having a pivotal journal pin of circular cross section which is a snap-fit connection in a corresponding pivotal bearing bush formed in a second pivotal part, the snap-fit connection being provided by a cooperating annular projection and annular recess, the projection being formed on one pivotal part and the recess being formed in the other pivotal part, each pivotal part having a substantially axially extending swivel stop for limiting the pivotal displacement of the joint.

2. A pivotal joint as claimed in claim 1, in which the annular projection is formed on the journal pin and the annular recess is formed in the bearing bush.

3. A pivotal joint as claimed in claim 2 in which the journal pin and the annular projection are made of resiliently deformable synthetic material.

4. A pivotal joint as claimed in claim 2 in which the bearing bush is made of resiliently deformable synthetic material.

5. A pivotal joint as claimed in any of the preceding claims, in which one of the swivel stops is a lug which is received in a recessed portion in the other pivotal part.

6. A pivotal joint as claimed in claim 5 in which the recessed portion extends parallel to the pivoting axis of the joint.

7. A pivotal joint as claimed in claim 5 or claim 6 in which the recessed portion is substantially an arc of a circle about the pivoting axis, and terminates in end walls arranged to limit the motion of the lug in the two pivotal directions.

8. A pivotal joint as claimed in any of claims 5 to 7 in which the pivotal part having the recessed portion has a similar second recessed portion formed on the opposite side of the said pivotal part for receiving the lug when the joint is assembled with the pivotal part having the lug turned through 1800.

9. A pivotal joint as claimed in any preceding claim, in which a prestressed torsion spring encircles the pivoting axis, one end of the spring being fixed to one pivotal part and the other end of the spring being fixed to the other pivotal part.

10. A pivotal joint constructed and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. second pivotal part 17 selectively relative to the first pivotal part 16, the second pivotal part 17 has a second recessed portion 44 which is disposed in a mirror-image fashion relative to the first recessed portion 27 and whose end edges 45 may likewise co-operate with the side surfaces of the lug 26 when the two pivotal parts 16 and 17 are correspondingly assembled i.e. when part 16 has been turned through 1800. In this case, naturally, a torsion spring wound in the opposite direction to the above-described embodiment must be used, one end 31 of which then being fixed in a second groove 46 disposed in a mirror-image fashion relative to the groove 36 (Fig. 2). WHAT WE CLAIM IS:

1. A pivotal joint for a wiper device for a screen of a motor vehicle which joint comprises a first pivotal part adapted to receive a wiper blade and having a pivotal journal pin of circular cross section which is a snap-fit connection in a corresponding pivotal bearing bush formed in a second pivotal part, the snap-fit connection being provided by a cooperating annular projection and annular recess, the projection being formed on one pivotal part and the recess being formed in the other pivotal part, each pivotal part having a substantially axially extending swivel stop for limiting the pivotal displacement of the joint.