GB2334749A

GB2334749A - Adjustable friction slider

Info

Publication number: GB2334749A
Application number: GB9904494A
Authority: GB
Inventors: Terence James Dolman
Original assignee: Trojan Hardware and Design Ltd
Current assignee: Trojan Hardware and Design Ltd
Priority date: 1998-02-27
Filing date: 1999-03-01
Publication date: 1999-09-01
Anticipated expiration: 2019-03-01
Also published as: GB2334749B; GB9804096D0; GB9904494D0

Abstract

In a variable-friction slider 29 for slidably and pivotally coupling two members, e.g. a link 10 and a track 12 of a window stay, comprising a plastics moulding 29 located in the track so as to engage its flanges 16,18 and a clamping member 28 forming an insert in the moulding and receiving clamping means 54 to apply adjustable clamping pressure to the upper side of the track the clamping member 28 is rotatable relative to the moulding 29 and the latter is formed with a reinforcing plate 44 extending through the moulding to distribute clamping forces from the clamping member.

Description

ADJUSTABLE FRICTION SLIDER This invention relates to improvements in variable friction sliding couplings, and in particular to couplings for use in windowmechanisms.

There is described in GB-A-2 304 148 a scissors-type window hinge comprising a crossed pair of pivotally interconnected links which extend between a supporting rail secured to a window sash and a channel-form rail secured to the window frame. One link is connected at one end to the sash rail by means of a fixed pivot, and at its other end to the channel by means of a normally fixed locating block, The other link is connected to the channel by means of a sliding block and to the sash rail by a pivot which is slidable along a slot in the rail.

For best positioning of the window (when open) it is desirable with such a mechanism that the sliding block be free to move along the channel as near to an adjacent corner of the window frame (i.e. as near to the adjacent end of the channel) as possible. This ordinarily means that it is desirable that the sliding block be free to move over the heads of fixing screws which have been inserted through a bottom wall of the channel into the frame, without any risk of engagement between the block and the screw heads. To that end, the sliding block should be arranged to slide in the channel with good clearance between the block and the bottom wall of the channel.

As well as securing and guiding the end of the associated hinge link, the sliding block serves a further purpose of introducing a variable degree of stiffness into the hinge. To that end, the block comprises an adjusting screw which enables the amount of friction between the block and the channel to be varied.

Other forms of window hinge also employ such sliding friction blocks but may not require the block to travel over securing screws at the channel end. In that case an adjusting mechanism of the block can be arranged to bear down on the bottom wall of the channel, whereby the mechanism acts between the bottom wall and undersides of edge flanges overlying the channel void.

In the case of the scissors-type hinge mechanism described in GB-A-2 304 148 an adjusting mechanism is employed which acts between upper sides and undersides of such edge flanges, the flanges thereby being pinched for frictional effect and there being no engagement with the bottom wall of the channel. The manner in which this is done is for an end portion of the associated hinge link to be located non-rotationally on a moulded slide bearing which lies across upper surfaces of the channel (comprising upper sides of edge flanges of the channel). A clamping bush extends up between the channel edge flanges, from the channel void, and through an aperture in the slide bearing, the bush being non-rotatably located in the slide bearing; the link, the slide bearing and the bush are so locked together rotationally. A head at the bottom end of the bush is wider than the spacing between the edge flanges, and a friction pad is trapped between the head and the undersides of the edge flanges. The edge flanges are so trapped between the friction pad and the slide bearing and variable pressure can be applied by means of a clamping screw which is introduced downwardly through an aperture in the hinge link to engage in a tapped bore in the bush, a head portion of the screw overlying and bearing against upper surfaces of the hinge link as the screw is tightened to draw the friction pad and the slide bearing towards one another.

Difficulties have been encountered with the engagement between the bush head and the friction pad, there being a tendency for the bush to rock in its location in the friction pad. The rocking of the bush relative to the pad results in damage to the pad, and ultimately the'bush head can wear a hole in the pad.

It is an object of the present invention to provide an improved construction of adjustable friction slider suitable for use in a hinge mechanism such as is described in GB-A-2 304 148.

The invention provides, in one of its aspects, a variable-friction sliding coupling comprising a first member, a second member comprising spaced opposed flanges, and means coupling the first and second members together and permitting relative movements there between both longitudinally of the flanges and pivotally about an axis extending transversely of the flanges, the coupling means comprising a slider which extends laterally beneath the flanges, and adjustable clamping means which is engaged with the slider and which bears down on said first member above the flanges, whereby a variable clamping pressure can be applied to the flanges between the clamping means and the slider, the slider comprising a clamping member which is operatively engaged by the clamping means and which is incorporated as a rotatable insert in a plastics moulding which forms friction pads positioned beneath the flanges, the slider comprising also a load-distributing reinforcing arm which extends from the rotatable clamping member through the moulding to distribute forces which are in use transmitted from the clamping member to the moulding in clamping the flanges.

It is to be understood that directional references used in the last preceding paragraph (and elsewhere herein) are relative and not absolute and are employed for convenience of description and do not presuppose any particular orientation of such an assembly in use.

The first member may comprise on its underside a separately formed bearing member which bears slidingly against upper surfaces of the second member to ease relative longitudinal movements between the first and second members.

The rotatable clamping member of the slider may be screwthreaded for operative engagement by screw-threaded clamping means.

The clamping member may comprise a bottom-end circular flange extending about its periphery, whereby it is rotatably secured within the moulding (being rotatable relative to both the moulding and the reinforcing arm); the flange is preferably of sufficient diameter to extend beneath the flanges of the second member. The reinforcing arm may comprise a thin plate which may lie over the flange of the clamping member, the plate and at least upper surfaces of the flange being enveloped by the moulding. The clamping member and the plate may each be of metal, the former being preferably of brass and the latter being preferably of stainless steel.

The invention provides, in another of its aspects, coupling means suitable for use in an assembly according to the last preceding paragraph but three, the coupling means comprising a slider and clamping means operatively engageable therewith and the slider comprising a plastics moulding which forms laterally spaced friction pads for engagement with undersurfaces of the flanges of the second member, a rotatable clamping member which is incorporated into the moulding between the friction pads for operative engagement by the clamping means, and a reinforcing arm which extends from the clamping member through the moulding to distribute forces which are in use transmitted from the clamping member to the moulding in clamping the flanges.

There now follows a description, to be read with reference to the accompanying drawings, of a sliding coupling assembly which illustrates the invention by way of example.

In the accompanying drawings: Figure 1 is a view in transverse cross-section through the assembly; Figure 2 is a view in plan of a friction pad moulding which incorporates a guide member; and Figure 3 is a view in longitudinal cross-section through the moulding.

There is shown in Figure 1 a cross-sectional view of a variablefriction sliding coupling assembly wherein a stay 10 of a window hinge mechanism is movably secured to a member forming a rail 12. The hinge mechanism is of the kind described in GB-A-2 304 148. The rail 12 would ordinarily be secured to a window frame, the hinge mechanism extending between the frame and a window sash.

In the orientation of the assembly displayed in Figure 1, the stay is coupled to the rail in a manner permitting it to move both horizontally (longitudinally of the rail) and pivotally about a vertical axis (extending perpendicularly to the rail).

The rail 12 forms a shallow channel 14, laterally spaced co-planar edge flanges 16, 18 of the rail opposing one another at the mouth of the channel and forming therebetween a guide slot 20.

The stay 10 comprises a metal arm 22 and a moulded plastics slide bearing 24, an end portion of the arm being located in a recess in the slide bearing. The slide bearing rests on flat upper surfaces 26 of the rail 12 which includes upper surfaces of the edge flanges 16, 18.

Coupling means connecting together the stay 10 and the rail 12 comprises a slider which includes a clamping member 28 which is located slidably and rotatably within the guide slot 20 between the edge flanges 16,18. The clamping member is incorporated as an insert in a reinforced plastics friction pad moulding 29 which is accommodated within the channel 14 to leave a clearance between the underside of the moulding and the bottom of the channel. The slider moulding is shown separately in Figures 2 and 3.

The clamping member is formed of brass and comprises a hexagonal head 30, a cylindrical body 32, and a circular flange 34 extending about its periphery at its bottom end. A frusto-conical portion 36 joins the cylindrical body 32 to a short cylindrical boss 38 immediately above the flange 34. The member is of least diameter at the cylindrical body 32, a projecting annular shoulder 40 being formed between the body and an outwardly-flared bottom end portion 42 of the head.

A thin stainless steel reinforcing plate 44 is located on the boss 38 of the clamping member, the plate resting on the flange 34. The clamping member is free to rotate relative to the plate. The plate is broader than the clamping member and extends for some distance radially from the clamping member (as seen in Figure 3).

The reinforcing plate is encapsulated in the plastics body 29, the plastics body also surrounding the clamping member between the shoulder 40 on the underside of the head and bottom-most surfaces of the clamping member below the flange 34. The clamping member is free to rotate relative to the moulded body, but is retained axially in the body by virtue of the body material positioned between the head shoulder 40 and the flange 34.

As seen in Figures 1 and 2, the moulded body 29 comprises a central generally-rectangular portion 48 of similar width to the maximum diameter of the brass clamping member 28 other than at the flange 34, and is of similar width to the rail slot 20 in which it fits slidingly. Flanks 50, 52 of the moulding are of lesser thickness and extend along the longer sides of the central portion 46 to form friction pads which lie beneath the edge flanges 16, 18 of the rail. The width of the reinforcing plate 44 is such as to extend almost to the outer edges of the pads, and the flange 34 of the clamping member also extends into the pads.

The clamping member is internally screw-threaded to receive clamping means comprising a headed screw 54. The hexagonal head 30 of the clamping member is accommodated within matching hexagonal openings in the slide bearing 24 and the stay arm 22 and the head of the clamping screw bears down on upper surfaces of the stay arm around the opening. By tightening the screw into the clamping member the assembly of the stay arm 22, the slide bearing 24 and the rail 12 becomes clamped to an adjustable degree between the underside of the screw head and upper surfaces of the friction pads 50, 52 engaging undersurfaces of the rail edge flanges 16, 18. The degree of friction between the friction pads and the edge flanges can so be set by means of the clamping screw.

It is to be noted that the assembly of the stay arrfl 22, the slide bearing 24, the brass clamping member 28 and the clamping screw 54 is free to rotate together relative to the rail 12 and the friction pad moulding 29, rotation occurring about the axis of the clamping member which extends perpendicularly to the slot 20 and the edge flanges 16, 18.

Pivoting movements of the stay arm about that axis in use of the mechanism have no effect, therefore, on the clamping action of the screw and clamping member.

The friction pad moulding is of glass-filled nylon, for strength and good wear resistance. The reinforcing plate 44 within the friction pad moulding 29 serves to stiffen the moulding, acting as a load-distributing arm to distribute forces which become applied to the moulding by the flange 34 of the clamping member during use. The plate also provides wear surfaces adjacent to the flange 34, preventing the flange from wearing into the moulded material, particularly due to any tendencies for the axis of the member to rock.

Claims

CLAIMS 1. A variable-friction sliding coupling comprising a first member, a second member comprising spaced opposed flanges, and means coupling the first and second members together and permitting relative movements therebetween both longitudinally of the flanges and pivotally about an axis extending transversely of the flanges, the coupling means comprising a slider which is engaged laterally beneath the flanges, and adjustable clamping means which is engaged with the slider and which bears down on said first member above the flanges, whereby a variable clamping pressure can be applied to the flanges between the clamping means and the slider comprising a clamping member which is operatively engaged by the clamping means and which is incorporated as a rotatable insert in a plastics moulding which forms friction pads positioned beneath the flanges, the slider comprising also a load-distributing reinforcing arm which extends from the rotatable clamping member through the moulding to distribute forces which are in use transmitted from the clamping member to the moulding in clamping the flanges.
2. A variable-friction sliding coupling according to claim 1 in which the first member comprises on its underside a separately formed bearing member which bears slidingly against upper surfaces of the second member to ease relative longitudinal movements between the first and second members.
3. A variable-friction sliding coupling according to claim 1 or claim 2 in which the rotatable clamping member of the slider is screw-threaded for operative engagement by screw-threaded clamping means.
4. A variable-friction sliding coupling according to any preceding claim in which the clamping member comprises a bottom-end circular flange extending about its periphery, whereby it is rotatably secured within the moulding relative to both the moulding and the reinforcing arm.
5. A variable-friction sliding coupling according to any preceding claim in which the flange is of sufficient diameter to extend beneath the flanges of the second member.
6. A variable-friction sliding coupling according to any preceding claim in which the reinforcing arm comprises a thin plate which lies over the flange of the clamping member, the plate and at least upper surfaces of the flange being enveloped by the moulding.
7. A variable-friction sliding coupling according to any preceding claim in which the clamping member and the plate are each of metal.
8. A variable friction sliding coupling substantially as described herein with reference to the accompanying drawings.
9. A coupling means suitable for use in any assembly according to any one of claims 1 to 7, the coupling means comprising a slider and clamping means operatively engageable therewith and the slider comprising a plastics moulding which forms laterally spaced friction pads for engagement with undersurfaces of the flanges of the second member, a rotatable clamping member which is incorporated into the moulding between the friction pads for operative engagement by the clamping means, and a reinforcing arm which extends from the clamping member through the moulding to distribute forces which are in use transmitted from the clamping member to the moulding in clamping the flanges.
10. A coupling means substantially as described herein with reference to the accompanying drawings.