GB2227518A

GB2227518A - Biasing unit and backplate assembly

Info

Publication number: GB2227518A
Application number: GB9000622A
Authority: GB
Inventors: Malcolm John Glover; Terence Maher
Original assignee: Newman Tonks Hardware Ltd
Current assignee: Newman Tonks Hardware Ltd
Priority date: 1989-01-11
Filing date: 1990-01-11
Publication date: 1990-08-01
Anticipated expiration: 2010-01-11
Also published as: GB2227518B; GB9000622D0; GB8900570D0

Abstract

A biasing unit and backplate assembly comprises a biasing unit (10) of cartridge form, a carrier (20) for the biasing unit, a backplate (40), with a hole (42) therethrough, for securement to a face of a door, and a nylon retaining bush (33) for securing the carrier to the backplate, the biasing unit being snap-fitted to the nylon carrier by a pair of flexible arms (28, 29), the retaining bush having a number of flexible fingers at its end remote from a flange (34), the hole (42) receiving a projection (24) on the carrier, the fingers passing, on assembly, through a hole in said projection and snap-fitting into a larger diameter hole in the carrier base (22), surfaces of the fingers engaging an annular shoulder (23a) between the holes in the carrier so that the flange of the retaining bush is tightly against one side of the backplate and the carrier, with the biasing unit, against the other. <IMAGE>

Description

BIASING UNIT AND BACKPLATE ASSEMBLY This invention relates to a biasing unit and backplate assembly for mounting a handle at one side of a movable wing. Normally the handle would be a door handle and would be mounted at a door, so that the biasing unit provides a spring action which is additional to the spring action provided by the latch operated by the handle.

U.K. Patent No. 2044337B relates to a biasing unit of this form and describes and illustrates the use of the biasing unit in a conventional channel shaped backplate, where opposite sides of the biasing unit engage respective opposite sides of the backplate. However the biasing unit is used with other forms of backplate, such as a square or rectangular plate, and an alternative form of fixing must be used. At present the biasing unit is received in an aluminium carrier and welded thereto, the carrier having a rear projection which is press-fitted into a correspondingly shaped hole, formed by piercing, in the aluminium backplate.

Not only is it difficult to achieve the required tolerances, but the connection of the biasing unit to the carrier by welding has proved unreliable due to the treated surfaces involved.

An object of the present invention is to provide a biasing unit and backplate assembly which reduces or overcomes the problem mentioned above.

According to the invention a biasing unit and backplate assembly comprises a biasing unit, a carrier for the biasing unit, a backplate having an aperture therethrough and a retaining element, the biasing unit and the carrier being fitted together, in use, the carrier having a part adapted to be received in said aperture in the backplate, and said retaining element and the carrier being fitted together, in use, such engagement securing the carrier at one side of the backplate, one or both of the biasing unit and the carrier and/or one or both of the carrier and said retaining element having means for carrying out said fitting together as a snap-fit.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a top plan view of a body of a biasing device forming part of the present invention, Figure 2 is an underneath plan view of the biasing unit, Figures 3 and 4 are cross-sectional views on the lines 3-3 and 4-4 of Figure 1, Figures 5 and 6 are a top plan view and a side view respectively of a cover of the biasing unit, Figure 7 is a plan view of a stop member of the biasing unit, Figures 8 and 9 are a top plan view and an underneath plan view respectively of a carrier for the biasing unit, Figure 10 is a half-sectional view on the line 10-10 of Figure 9, Figures 11 and 12 are an end view and a sectional view on the line 12-12 of Figure 11 respectively of a retaining washer, on a smaller scale, Figure 13 is a schematic, exploded, perspective view of the fitting together of a biasing unit and backplate assembly of the invention, with a door handle also being shown, and Figures 14 and 15 are an end view and a side view respectively of a bush for engagement with the backplate when the biasing unit is not used.

The biasing unit itself comprises a generally square body 10 with bevelled corners, and a central, circularsection through bore 11. The interior of the body is substantially the same as that described for the biasing unit of U.K. Patent Specification No. 2044337, differing in two aspects only. Firstly the end surfaces of the channels terminate in angled surfaces 12, 13 respectively instead of radial surfaces. This means that the end surfaces 14, 15 respectively of the stop member 16 are likewise angled instead of being radial. Secondly, the body has four part-circular through holes 17 therein to receive four correspondingly positioned pegs 18 extending from the inner surface of the biasing unit cover part 19, when the cover part 19 engages on the body part to close it. The pegs 18 engage in the holes 17 as tight frictional fits.The body and the cover part are both made of plastics material, such as nylon, and the stop member 16 can also be of nylon. Thus only the springs in the body 10 would be of the same material as those shown and described in the Patent. The springs can have plugs in the respective ends thereof engaged by the stop member.

When assembled, the biasing unit, in the form of a cartridge, would operate in exactly the same manner as described in the Patent, being self contained, with angular movement of the stop member 16 by operation of a handle, being resisted by the spring which tend to return the stop member, and the handle, to their respective rest positions.

Figures 8 to 10 show a nylon material carrier 20 into which the biasing unit is intended to fit. The carrier 20 has the same outline shape as the biasing unit being square with bevelled corners 21. A base 22 of the carrier has a stepped, central, circular hole 23 therein, the hole extending through a projection 24 on the rear surface of the base 22, the projection having a generally star-shaped outer surface formed by two equally sized squares superimposed on one another with one square at 450 to the other. The end of the hole 23 at the end of the projection is chamfered at 25. The diameter of the part-circular portion of the aperture through the stop member 16 is smaller than that of the smaller portion of the stepped hole in the base 22.

Along the whole of one pair of parallel edges, the carrier base is formed with integral, upstanding sides 26, 27 respectively. The sides extend from the base 22 by approximately the depth of the biasing unit. At the other pair of parallel edges are formed integral upstanding arms 28, 29 respectively, each of which is centrally disposed along its associated edge and is much less wide than a side 26, 27. The arms are each reduced in width approximately half way along their length. The arms have respective inwardly extending lips 30, 31 at their free ends, outwardly facing surfaces of the lips respectively being chamfered inwardly. The arms are each of a length such that the inner surface of the lip is at the level of the free end of each side 26, 27.

In use, the biasing unit is fitted into the carrier with the parallel cavities in the body 10 parallel to the sides 26, 27. The arms 28, 29 engage the biasing unit as a snap-fit, being forced outwardly as the unit is received therebetween, the lips 30, 31 being forced outwardly, assisted by the chamfer on their outwardly facing surfaces, and then returning to snap-fit onto the outwardly facing surface of the unit, or the unit having slots 32 for the lips. The unit is then tightly held in the carrier.

Figures 11 and 12 shows a hollow nylon, one-piece retaining washer or bush 33, having an annular flange 34 at one end, a cylindrical stem 35, and four annular fingers 36 at its other end, formed by respective short cuts 37, parallel to the axis of the bush, from said other end. At their ends, the fingers are each outwardly chamfered, as shown at 38, and have an annular shoulder 39. The washer has a length dependent upon the thickness of backplate with which it is to be used. Its various radial dimensions are such that its shoulders 39, formed on the underside of the fingers, can engage on the annular shoulder 23a formed at the step of the hole 23 in the carrier 20 while the stem 35 passes through the smaller diameter portion of stepped hole 23. The outer diameter of the finger area is greater than the diameter of the smaller portion of stepped hole 23.

Figure 13 schematically shows the arrangement for fitting together the biasing unit, a carrier 20, the washer 33 and a backplate 40, as well as a lever door handle 41.

It can be seen that the square backplate, for example of aluminium, has a star-shaped pierced hole 42 through it which matches the projection 24, but is very slightly larger. The projection, and thus the carrier, can thus be fitted to the backplate in any one of eight orientations at 450 to each other. Of course the orientation chosen will affect the orientation of the handle in its rest position.

Thus on assembly, the biasing unit can be snap-fitted into its carrier 20 as described and the carrier projection engaged in the chosen orientation in the hole 42. The rear surface of the projection will lie flush with the adjacent surface of the backplate. The washer 33 is then pushed into the hole 23. This causes the fingers to be squeezed together until they clear the smaller portion of hole 23, whereupon they spring outwardly and their shoulders 39 may engage tightly on the shoulder 23a and behind the biasing unit. The length of the washer is such that the underside of the flange 34 tightly engages the surface of the backplate opposite to that engaged by the carrier. The carrier is thus tightly snap-fitted to the backplate by means of the washer, the biasing unit being tightly snap-fitted to the carrier by the arms 28, 29.These arms are only shown very schematically in Figure 13 and would actually be as shown in Figures 8 to 10.

Thereafter the backplate can be secured at one side of a door by screws passing through holes (not shown) in the backplate 40, the door having a recess to receive the carrier 20. A spindle (not shown) of the latch unit of the door would extend through the door to be received through the biasing unit and into the shank of the handle. A similar arrangement could be provided at the other side of the door. In use, the biasing unit operates when the handle is moved angularly to supplement the spring bias of the latch in returning the handle to its rest position. The two snap-fit assembly steps are relatively quick and easy to effect and the resultant construction overcomes the problems mentioned with the arrangement presently used, as tolerances are no longer critical and no welding is required. Disconnection is also of course possible in a relatively easy manner.

If it is wished to use the handle and backplate without the biasing unit (and carrier), the washer 43 of Figures 14 and 15 replaces the washer 33 and the carrier and biasing unit are removed. The washer 43 has a circular flange 44 and a stem 45 having a star-shape and sized to be received as a tight fit in the hole 42.

Instead of the flat backplate 40 shown, the backplate could of course alternatively be of any other suitable form, for example of conventional channel shape with an aperture for the reception of part of the carrier.

Claims

1. A biasing unit and backplate assembly, comprising a biasing unit, a carrier for the biasing unit, a backplate having an aperture therethrough and a retaining element, the biasing unit and the carrier being fitted together, in use, the carrier having a part adapted to be received in said aperture in the backplate, and said retaining element and the carrier being fitted together, in use, such engagement securing the carrier at one side of the backplate, one or both of the biasing unit and the carrier and/or one or both of the carrier and said retaining element having means for carrying out said fitting together as a snap-fit.

2. An assembly as claimed in Claim 1, wherein one of the retaining element and the carrier part has a number of flexible fingers which are deformable as the retaining element and the carrier are fitted together, the fingers thereafter acting to retain said fitting together.

3. An assembly as claimed in Claim 2, wherein the retaining element is a bush having a flange at one end and a number of flexible fingers at its other end, the carrier having internal shoulder means against which when the bush and carrier are fitted together respective surfaces of the fingers engage to prevent separation of the carrier and the bush, with the flange held against the backplate at its opposite side to the carrier.

4. An assembly as claimed in Claim 4, wherein the bush is formed in one-piece of plastics material, the carrier having a base with a projection on its rear surface forming said part thereof, a circular hole through the base and a co-axial smaller diameter circular hole, forming said aperture, through said projection defining an annular shoulder surface therebetween, the fingers of the bush having respective chamfered outer surfaces and respective flat inner surfaces so that the chamfered surfaces engage the outer surface of the projection and are deformed inwardly as the bush and carrier move relatively, in use, towards each other on assembly, the fingers expanding outwardly once they are clear of the hole in the projection to snap-fittingly engage the shoulder with their flat surfaces, the flange being held tight against an outer surface of the backplate, and the carrier held at an inner surface thereof.

5. An assembly as claimed in any one of the preceding claims, wherein the part of the carrier adapted to be received in said aperture and said aperture are of correspondingly polygonal shape so that the carrier part can be received in said aperture in at least two alternative selected positions, angularly spaced apart by less than 900.

6. An assembly as claimed in Claim 5, wherein the outer surface of said carrier part is generally star shaped, formed by two equally sized squares superimposed on one another with one square at 450 to the other.

7. An assembly as claimed in any one of the preceding claims, wherein the carrier has at least two, flexible arms between which the biasing unit can be fitted, the arms deforming outwards as the biasing unit is received therebetween, and thereafter returning to their undeformed state to retain the biasing unit.

8. An assembly as claimed in Claim 7, wherein the carrier has two spaced, parallel arms, each arm having a lip at its outer end, the lip having a chamfered outer surface and a flat inner surface, the chamfered surfaces of the respective lips engaging the biasing unit when it is fitted to the carrier and the arms are forced outwardly, the flat inner surfaces of the lips thereafter snap-fitting onto the biasing unit to hold it to the carrier.

9. An assembly as claimed in Claim 8, wherein the carrier has a pair of spaced, parallel sides, disposed normally to said arms thereof, which engage respective parallel sides of the biasing unit when it is fitted to the carrier by said snap-fit of the arms.

10. An assembly as claimed in any one of the preceding claims wherein the carrier is of plastics material.

11. An assembly as claimed in any one of the preceding claims, wherein the biasing unit has a body part, a stop member angularly movable in the base part and a cover, all of which are of plastics material.

12. An assembly as claimed in Claim 11, wherein the cover has a plurality of pegs received in corresponding bores in the body part as an interference fit to secure it to the body part.

13. A biasing unit and backplate assembly substantially as hereinbefore described with reference to and as shown in Figures 1 to 13 of the accompanying drawings.