GB2263392A

GB2263392A - A wiper blade yoke assembly

Info

Publication number: GB2263392A
Application number: GB9200827A
Authority: GB
Inventors: Cedric Sheng Kao Charng
Original assignee: CHINA WIPER SPECIAL RUBBER CO; China Wiper Special Rubber Co Ltd
Current assignee: CHINA WIPER SPECIAL RUBBER CO; China Wiper Special Rubber Co Ltd
Priority date: 1992-01-15
Filing date: 1992-01-15
Publication date: 1993-07-28
Anticipated expiration: 2012-01-15
Also published as: GB9200827D0; GB2263392B

Abstract

A wiper blade yoke assembly comprises a main yoke having spaced apart side walls (30, 31) with different sized holes (32, 33) therein and a pivot pin (21) making snap-fit connection within the said wall holes (32, 33). The pivot pin (21) has a resiliently deformable head (22) having a maximum dimension larger than that of the smaller side wall, hole (33) and preferably no larger than that of the larger side wall hole (32). <IMAGE>

Description

A wiper blade yoke assembly This invention relates to a wiper blade yoke assembly of the kind comprising a main yoke having spaced apart first and second side walls with aligned first and second holes, respectively, therein, and a plastics pivot pin making snap fit connection within the first and second holes, the pivot pin having an enlarged rear end which is too large to pass through either of said first and second holes and a resiliently deformable front end, the latter being insertable through said first hole for making snap fit connection in said second hole.

In a known wiper blade yoke assembly of the kind referred to, each of the first and second holes are of a similar size. In order to connect the first pin, which is conveniently of plastics material, between the first and second side walls during manufacture of the wiper blade yoke assembly, it is necessary to push the front end of the pivot pin through the first hole and then into snap fit connection with the second hole. The front end of the pivot pin thus needs to be resiliently deformed twice during the manufacturing process as it is pushed through both the first and second holes. This hinders and complicates the manufacturing process.

The present invention seeks to provide a design of wiper blade yoke assembly which facilitates its manufacture.

According to the present invention a wiper blade yoke assembly of the kind referred to is characterised in that said first hole is larger than said second hole.

By having the first hole larger than the second hole, connection of the pivot pin to the main yoke is facilitated, since the front end of the pin is more easily inserted through the first hole during the assembly process.

Preferably the front end of the pivot pin has a maximum transverse dimension, when not resiliently deformed, which is greater than a maximum transverse dimension of the second hole and is less than or equal to a maximum transverse dimension of the first hole.

Preferably each of said first and second holes is circular and the pivot pin has a first annular portion which seats within the first hole and a second annular portion, of smaller diameter than, and axially spaced from, said first annular portion, which seats within the second hole.

Preferably the second annular portion provides a cylindrical surface having a diameter less than or equal to the diameter of said second hole. Conveniently the first and second annular portions are joined by a cylindrical central portion having a diameter less than or equal to that of said second annular portion.

Conveniently the front end of the pivot pin comprises a head consisting of a number, e.g. two, of head parts which can be resiliently urged towards each other to reduce the size of the head. Preferably the head has a frusto-comical surface which assists resilient inward movement towards each other of the head parts as the head is pushed through the second hole during snap fit connection of the pivot pin to the main yoke.

An embodiment of the invention will now be described, by way of example only, with particular reference to the accompanying drawings, in which: Figure 1 is a sectional view through part of a main yoke of a known wiper blade yoke assembly with a pivot pin connected thereto; Figure 2 is a schematic perspective view of part of a wiper blade yoke assembly according to the invention and showing pivot pin snap-fit connected to a main yoke; Figure 3 is a sectional view through the main yoke of Figure 2; and Figure 4 is a similar sectional view to that of Figure 3 but showing the pivot pin in a position ready to be inserted through aligned holes in side walls of the main yoke for snap fit connections to the main yoke.

Figure 1 shows a pivot pin connection of a known wiper blade yoke assembly. In particular this known construction comprises spaced apart side walls 1 and 2 of a metallic main yoke having an equal size circular hole 3 and 4 formed, respectively, therein. A plastics pivot pin 5 is snap-fit connected to the main yoke and has a cylindrical front end portion 6, with a diametric groove 7 formed therein, which is received within the hole 4, a similarly sized cylindrical rear end portion 8 received within the hole 3, a reduced diameter cylindrical central portion 9 extending between the portions 6 and 8 and an enlarged rear end cap 10. The front end portion 6 has a diameter slightly larger than that of each of the holes 3 and 4 but is resiliently contractible, by virtue of the groove 7, so that it can be pushed through the holes 3 and 4 when the pivot pin is connected to the main yoke.

However it will be appreciated assembly of the known wiper blade yoke assembly is complicated by the fact that the front end portion 6 of the pivot pin 5 has to be resiliently contracted twice as it is push fitted firstly through the hole 3 and then through the hole 4 in order to make snap-fit connection with the main yoke. In the manufacture of large volumes of wiper blade assemblies, the manual process of connecting pivot pins to main yokes can constitute a significant period of time in the assembly process and any means of facilitating this part of the assembly process can result in significant savings both in manufacturing time and costs.

Figures 2 to 4 show a wiper blade yoke assembly according to the invention in which pivot pin connection to a metallic main yoke 20 is facilitated. The pivot pin, designated by the reference numeral 21, is made of plastics material and comprises an enlarged frusto-conical head 22 adjacent an annular front portion 23 having a cylindrical surface, an annual rear portion 24 also having a cylindrical surface, a cylindrical central portion 25 extending between the annular portions 23 and 24 and an enlarged rear end cap 26. A diametric slot 27 is formed in the front end of the pivot pin and extends axially through the head 22 and into the front portion 23. The provision of the slot 27 divides the head 22 into two parts 22a and 22b which can be resiliently deflected towards each other.

The head 22 in its normal, undeformed condition, has a diameter X and the front portion 23 has a diameter W. The diameter of the rear portion 24 is typically also X.

The main yoke 20 has spaced apart side walls 30 and 31 having circular first and second holes 32 and 33, respectively, formed therein. The first hole 32 has a diameter Y which is greater than the diameter Z of the second hole 33. Ideally the following conditions apply with regard to the various diameters of the holes of the main yoke and portions of the pivot pins: Y > X > Z > W During connection of the pivot pin 21 to the main yoke 20, the frusto-conical head 22 is sufficiently small to pass with little or no interference through the first hole 32.

On reaching the second hole 33, the inclined frusto-conical walls of the head parts 22a and 22b engage the walls of the hole 33. As the head is pushed into the hole-33, the head parts 22a and 22b are resiliently deflected towards each other until the head 22 is pushed fully through the hole 33 whereupon the head parts 22a and 22b spring apart into their normal undeflected condition. When the pivot pin 21 is snap-fitted into this connected position, the annular front portion 23 is seated within the second hole 33 and the annular rear portion is seated within the first hole 32.

The enlarged rear end cup 26 is too large to pass through the first hole 32 and the shoulders between the head parts 22a and 22b and the front portion 23 prevent the pivot pin 21 being withdrawn unintentionally back through the second hole 33. Assembly of the pivot pin 21 to the main yoke 20 is thus a simple manual process which can be performed both quickly and relatively cheaply.

Although it is preferred that the diameter X of the head 22 should be less than or equal to the diameter Y of the first hole 32 this is not, of course, essential. If X is only slightly greater than Y, it would still be a relatively simple process to push the head 22 through the first hole 32 compared with that of snap-fit connecting the head in the smaller diameter hole 33. It will also be realised that the diameter of the central portion 25 could be the same as, or even greater than, the diameter of the annular front portion 23, although the diameter of the central portion should not exceed the diameter of the annular rear portion 24.

Throughout this specification reference has been made to the yoke holes being circular and to the pivot pin being of circular cross-section. Although this design is preferred, it should be realised that the yoke need not be circular, in which case the cooperating parts of the pivot pin would suitably also be non-circular in section. For example the holes 32 and 33 could be square in which case the portions 23 and 24 would, similarly, also be square in section. The central portion 25 should preferably however, always be of generally circular cylindrical form.

Claims

1. A wiper blade yoke assembly comprising a main yoke having spaced apart first and second side walls with aligned first and second holes, respectively, therein, and a plastics pivot pin making snap fit connection within the first and second holes, the pivot pin having an enlarged rear end which is too large to pass through either of said first and second holes and a resiliently deformable front end, the latter being insertable through said first hole for making snap fit connection in said second hole, characterised in that said first hole is larger than said second hole.

2. A wiper blade yoke assembly according to claim 1, characterised in that the front end of the pivot pin has a maximum transverse dimension when not resiliently deformed, which is greater than a maximum transverse dimension of the second hole and is less than or equal to a maximum transverse dimension of the first hole.

3. A wiper blade yoke assembly according to claim 1 or 2, characterised in that each of said first and second holes is circular and in that the pivot pin has a first annular portion which seats within the first hole and a second annular portion of smaller diameter than, and which is axially spaced from, the first annular portion, which seats within the second hole.

4. A wiper blade yoke assembly according to claim 3, characterised in that the second annular portion provides a cylindrical surface have a diameter less than or equal to the diameter of said second hole.

5. A wiper blade assembly according to claim 3 or 4, characterised in that the first and second annular portions are joined by a cylindrical central portion having a diameter less than or equal to that of the second annular portion.

6. A wiper blade yoke assembly according to any one of the preceding claims, characterised in that the front end of the pivot pin consists of at least two head parts which can be resiliently urged towards each other to reduce the size of the head when it is pushed through the second hole.

7. A wiper blade yoke assembly according to claim 6, characterised in that the head parts have external surfaces which are inwardly inclined towards the front end of the pivot pin.

8. A wiper blade yoke assembly according to claim 7, characterised in that said external surfaces together lie on a frusto-conical surface.

9. A wiper blade assembly constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 2 to 4 of the accompanying drawings.