GB2238953A - Pivot joint for a windscreen wiper blade - Google Patents

Abstract

A pivot joint for pivotally connecting the arm (not shown) of a windscreen wiper to a blade comprises a joint body 2 including first attachment means for attaching a portion 6 of the body to one of the members to be pivoted ie the arm, second attachment means 12, 14, 16, 18, 20 for attaching another portion 4 of the body in an aperture 32 in the other of the members ie the blade 30 to be pivoted with sufficient play to allow pivotal movement between them, the second attachment means being provided with sprung retention means in the form of a detent 20 carried by a resilient tongue 18 extending from a pan of the joint body 2 intended to stay outside the aperture 32 of the blade. The detent 20 is movable between a first stable position in which it renders a dimension of the portion 4 too large to pass through the aperture 32 so as to retain the joint body 2 and a second unstable position in which it allows the portion 4 to pass through the aperture so that the joint body 2 can be assembled on and dissassembled from the blade 30. A stop 40 is associated with the resilient tongue 18 whereby flexing of the tongue 18 away from the joint body 2 is limited. The stop 40 may be attached to the detent 20 by ultrasonic welding. <IMAGE>

Description

PIVOT JOiNT This invention relates to a pivot joint which is suitable for connection of the arm of a windscreen wiper installation to the blade thereof.

In the manufacture of windscreen wipers, a number of pivot joints are used, particularly between the arm and blade thereof.

Problems exist in the manufacture of windscreen wipers due to the necessity, very often, of pivoting metal parts together. These tend to be noisy and have a tendency to suffer from wear and corrosion. Various proposals have been made for overcoming these problems, for example, by the provision of plastics members between the metal of the joints, but these have not proved entirely satisfactory from a manufacturing standpoint although they have worked satisfactorily in practice.

A proposal which has been found to be satisfactory in GBn 0215 practice was described in our prior British Patents Application No. 87/01948 (originally 86/02376).

According to this prior Application, a pivot joint comprised a joint body including first attachment means for attaching the joint body to one of the members to be pivoted, second attachment means for attaching the joint body with pivotal play to the other of the members to be pivoted, the second attachment means being provided with spring engagement means whereby the joint body can be assembled on the said other member.

In a particular application of that invention, the pivot joint was applied to the joint connecting the arm of a windscreen wiper with the wiper blade. Various proposals for attaching the arm to the pivot joint were made using both special arm terminations and a common arm termination known as a "hook" termination. in this application, the second attachment means comprised a tongue extending upwardly from from the bottom of the joint body and having an outwardly facing detent towards its free end which cooperated with an extension on the top of the joint body to engage therebetween an edge of an aperture provided in the main yoke of the windscreen wiper blade for pivotal purposes. While this arrangement was suitable for many applications, difficulties were sometimes found in the case where a windscreen wiper arm cannot be raised to any appreciable extent from the windscreen.In these circumstances, it can be difficult, if not impossible, to pivot the wiper blade relative to the wiper arm sufficiently for the two to be able to be detached.

Gss ozO7 osl041 proposal of our prior Patent: Application No.

83/17436 (originalLy 87/17532) proposed to overcome this problem, while using the same basic principles as were present in the earlier Application. To this end, the joint of the second Application comprised a joint body including first attachment means for attaching the body to one of the members to be pivoted, second attachment means for attaching a portion of the body in an aperture in the other of the members to be pivoted with sufficient play to allow pivotal movement between them, the second attachment means being provided with sprung retention means in the form of a detent carried by a resilient tongue extending from a part of the joint body intended to stay outside the aperture, which detent is movable between a first stable position in which it renders a dimension of the said portion too large to pass through the aperture in the said other member so as to retain the joint body on the said other member and a second unstable position in which it allows the said portion to pass through the aperture so that the joint body can be assembled on and dissassembled from the said other member.

This latter proposal worked very satisfactorily when fitting instructions were properly observed but problems arose where it was attempted to insert the joint body into the aperture in the blade the wrong way round. This has resulted in breaking off the detent and resilient tongue, leaving the blade in an unsafe condition. It will be understood that where the arm is permanently attached to the joint body and is located in the joint body in a position to lie above the wiper blade, incorrect assembly of the joint body to the wiper blade is prevented by engagement of the arm with the blade.

Thus the problem only arises where it is possible to assemble the joint body to the blade before attaching the arm and where the arm is attached to the joint body so as to lie parallel to and alongside the blade.

The present invention seeks to provide a pivot joint in which the above problem is substantially obviated.

According to the invention, a pivot joint comprises a joint body including first attachment means for attaching the body to one of the members to be pivoted, second attachment means for attaching a portion of the body in an aperture in the other of the members to be pivoted with sufficient play to allow pivotal movement between them, the second attachment means being provided with sprung retention means in the form of a detent carried by a resilient tongue extending from a part of the joint body intended to stay outside the aperture, which detent is movable between a first stable position in which it renders a dimension of the said portion too large to pass through the aperture in the said other member so as to retain the joint body on the said other member and a second unstable position in which it allows the said portion to pass through the aperture so that the joint body can be assembled on and dissassembled from the said other member, wherein stop means are associated with the resilient tongue whereby flexing of the tongue away from the joint body is limited.

In this way, the tongue cannot be flexed past its elastic limit and destruction thereof by incorrect fitting is substantially avoided.

Preferably the joint body is provided with a projection extending parallel to the tongue and the free end of the tongue is provided with a hook element which engages behind the projection so that the tongue cannot move outwardly of the joint body from its first position but only towards the joint body to its second position and back to its first position.

sne hook element may comprise an "L" shaped element attached or formed on the end of the tongue, the stem of the l'Lll extending in a direction opposite to the detent and the base of the "L" extending in towards the joint body so as to engage behind the said projection.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1 is a perspective view of a joint body to which the present invention can be suitably applied; Figure 2 is a sectional view taken on the line Il-Il of figure showing a joint body without the features of the present invention; Figure 3 is a sectional view showing an attempt at incorrect assembly of the joint body of figure 2 to a windscreen wiper blade; Figure 4 is a view similar to figure 2 but showing the modification introduced by the present invention, and Figure 5 is a sectional view showing an attempt at incorrect assembly of the joint body of figure 4 to a windscreen wiper blade.

Referring firstly to figures 1 and 2, a joint body 2 is shown having a first part 4 for insertion into an aperture in the wiper blade and a second part 6 for attachment of the wiper arm which is intended, in use, to lie alongside the wiper blade.

The first part 4 comprises an insertion portion 8 of substantially hollow rectangular construction which is intended to pass into the blade aperture and a head or top portion 10 which extends laterally beyond the insertion portion to form a rim 12 which is of such dimensions as to prevent the top portion 10 from entering the blade aperture. One end 14 of the insertion portion 8 has an axially extending projection 16 extending from the bottom thereof. At the other end 17 of the insertion portion 8 is a resilient tongue 18, depending from the top portion 10 parallel to the end 20 of the insertion portion 8.

The second part 6 of the joint body 2 is connected by means of a web 24 tom the top part 10 of the first part 4 and comprises a longitudinal slot 26, open at one end 28 to receive the end of a wiper arm.

For correct assembly, as has been described in greater detail in our prior Patent Application No. 88/17436, The end of the joint body carrying the tongue 18 is inserted into the blade aperture and pushed against one end of the aperture so as to flex the tongue 18 towards the insertion portion 8 and allow the other end of the joint body 2 to be pivoted into the aperture. Release of the joint body 2 will allow the tongue 18 to flex outwardly, thereby preventing the joint body 2 from being removed from the blade by engagement of the detent 20, carried by the tongue 18, with the edge of the blade aperture.

figure 3 shows the situation when an attempt is made to assembie the joint body onto the wiper blade, here indicated at 30, the wrong way round. In this case the end 14 carrying the projection 16 has first been inserted into the aperture 32 of the blade 30 and an attempt is then made to pivot the joint body 2 to insert the other end thereof into the aperture 32. If considerable pressure is used, the tongue 18 will flex outwardly as shown and will eventually break off, leaving the joint body unattached to the wiper blade. It is then possible, in certain circumstances, for the blade and arm to become accidentally detached with possibly hazardous consequences, both to the vehicle windscreen and also to passers by who could be hit by the detached blade.

Figure 4 shows the modification proposed by the present invention. Here the detent 20 is elongated somewhat and an 11L" shaped element 40 is formed thereon or attached thereto, for example, by ultrasonic welding. As can be seen, the stem 42 of the "L" extends backwards, in the opposite direction to the detent 20 and towards the insertion portion 8 of the joint body 2. The base 44 of the "L" extends upwardly from the rearmost part of the stem 42 of the "L" so as to engage behind the end 17 of the insertion portion 8.

As can be seen from figure 5, if an attempt is made to insert the joint body 2 incorrectly, excess pressure on the joint body to force the joint body into the aperture will fail to flex the tongue 18 outwardly as it is prevented from movement in this direction by engagement of the base 44 of the "L" shaped element 40 behind the end 17 of the insertion portion 8 of the joint body 2.

In this way, incorrect insertion and destruction of the tongue 18 is reliably prevented.

Wnile the invention has been described in relation to a joint body providing a connection for an arm lying alongside the blade, it could equally well be used on other joint bodies with similar means of connection. It will of course be appreciated that where the arm is permanently attached to the joint body and the arm is intended to lie above the wiper blade, the arm itself will foul the blade if incorrect assembly is attempted so that, in those circumstances, the invention is not required.

Claims (4)

1. A pivot joint for pivotally connecting two members together comprising a joint body including first attachment means for attaching the body to one of the members to be pivoted, second attachment means for attaching a portion of the body in an aperture in the other of the members to be pivoted with sufficient play to allow pivotal movement between them, the second attachment means being provided with sprung retention means in the form of a detent carried by a resilient tongue estenciing from a part of the joint body intended to stay outside the aperture, which detent is movable between a first stable position in which it renders a dimension of the said portion too large to pass through the aperture in the said other member so as to retain the joint body on the said other member and a second unstable position in which it allows the said portion to pass through the aperture so that the joint body can be assembled on and dissassembled from the said other member, wherein stop means are associated with the resi I lent t oligue whereby flexing of the tongue away from tlie joint body is limited.

2. A pIvot joint as claimed in claim 1, wherein the joint body is provided with a projection extending parallel to the tongue and the free end of the tongue is provided with a hook element which engages behind the project ion so that the tongue cannot move outwardly of the joint body from its first position but only towards the joint body to its second position and back to its first position.

3. A pivot joint as claimed in claim 2, wherein the hook element comprises an "L" shaped element attached to or formed on the end of the tongue, the stem of the "L" extending in a direction opposite to the detent and the base of the "L" extending in towards the joint body so as to engage behind the said projection.

4. A pivot joint substantially as described herein with reference to figures 4 and 5 of the drawings.