GB2403769A

GB2403769A - Offset bearing window stay

Info

Publication number: GB2403769A
Application number: GB0415408A
Authority: GB
Inventors: Ronald Percival Davis
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-07-11
Filing date: 2004-07-09
Publication date: 2005-01-12
Anticipated expiration: 2024-07-09
Also published as: GB0415408D0; NZ526960A; GB2403769B

Abstract

In a friction window stay for mounting a window sash in a window frame, the pivot joint 5 between the long arm 2 and the frame mounting member 3 is offset to one side of a longitudinal centreline of the frame mounting member. When the stay is fully closed, such that the sash mounting member 6 and frame mounting member 3 are substantially aligned, the long arm 2 extends at an angle relative to the longitudinal centre line of the frame mounting member, that is, from the long arm-sash mounting member pivot joint 8 to the offset long arm-frame mounting member pivot joint 5 The short arm-frame mounting member pivot joint 4 is also offset to the opposite side of said longitudinal centre line of the frame mounting member 3.

Description

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AN OFFSET BEARING WINDOW STAY

FIELD OF INVENTION

The present invention relates to window stays, and in particular a window stay which will typically be a friction stay suitable for supporting a window sash in either a casement or awning application.

BACKGROUND

A variety of forms of friction stays for windows are known. The four bar window stay the subject of New Zealand patent no. 144922/146130/146886, for example, has for over three decades proved particularly successful in its basic and subsequently refined forms, in many countries. The success of this four bar friction stay has derived from its simplicity of construction, because the stay does not have the externally exposed sliding pivot and track arrangement of pantograph type stays. Such externally exposed moving parts are prone with time to clogging with dirt causing sticking of the mechanism, increased wear and tear and so forth. Also, the geometry and operation of the four bay stay in use lifts the window sash out of the window aperture, enabling the provision of a peripheral sealing flange about the entire sash while still facilitating access for cleaning.

With conventional four bar friction stays, even when the window sash is closed, the stay itself is still a few degrees open. It is believed necessary that even when the window sash is closed, the friction stay not be fully closed to ensure correct operation of the stay when the window is again opened. With the four bar geometry, designers have ensured that the stay is slightly open even when the window is closed because of the danger that otherwise the stay might not operate correctly and that the head of the window could begin to move outwardly before the bottom of the window sash, which would result in jamming of the stay.

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Àe À: :.: New Zealand patent specification 238318/240289 discloses a four bar window stay in which the short arm-frame plate pivot joint is offset to one side of a longitudinal centre line ofthe frame plate.

Windows produced from uPVC instead of aluminium or wood have become popular, particularly in the replacement window market. The uPVC material is produced by extrusion and is then cut and the window sash(es) and frame(s) are constructed. A common standard uPVC extrusion profile has a cavity comprising a narrow groove to accommodate the stay between the sash and frame to suit pantograph type stays, and which will not accommodate a conventional four bar stay. Although the four bar friction stay is superior, it has not been possible to employ a four bar stay.

Also, because the four bar friction stay has not been allowed to close fully, for various reasons this has inhibited the use of some form of integral head locking mechanism with the four bay stay. Some form of head locking mechanism is desirable because of another disadvantage of the four bar stay, which is that the head can be forced open from outside the window frame, by levering between the peripheral sealing flange at the head of the window and the window frame with a crowbar for example. A separate locking device can be added between the window sash and frame on the inside of the window to counter this danger, but this is not as desirable as use of an integral mechanism.

SlnUAlAJRY OFIN\]ENTIO N It is an object of my present invention to provide an improved or at least alternative form of friction window stay which possesses advantages over the conventional four bar stay as will be described.

TO broad terms the invention comprises a friction window stay for mounting a window sash in a window frame, the stay including: a frame mounting member for securement of the stay to the frame of a window, a sash mounting member for securement of the stay to the sash of a window, a short arm having a pivot joint between a sash end of the short arm and the sash mounting member and a pivot joint between a frame end of the short arm and the frame mounting member, and a long arm having a pivot joint between a sash end of the long arm and the sash mounting member and a pivot joint between a frame end of the long arm and the frame mounting member which is offset to one side of a longitudinal centreline of the frame mounting member such that when the stay is fully closed, so that the sash mounting member and frame mounting member are substantially aligned, the long arm extends at an angle relative to the longitudinal centre line of the frame mounting member, from the long arm-sash mounting member pivot joint to the offset long arm-frame mounting member pivot joint.

Preferably the short arm-frame mounting member pivot joint is also offset, to the opposite side of said longitudinal centre line of the frame mounting member than said offset long arm-frame mounting member pivot joint, such that when the stay is fully closed the short arm extends at an angle relative to the longitudinal centre line of the frame mounting member, from the short arm-sash mounting member pivot joint to the short arm-frame mounting member pivot joint.

Preferably the stay of the invention also incorporates integral means to lock the head of the window against forced opening, comprising an engagement means on the short arm end of the sash mounting member which engages co-operable engaging means on the frame mounting member as the stay is closed, with the distance between the short arm- sash mounting member pivot joint and said engagement means on the end of the sash mounting member being less than two thirds, and most preferably less than one half, of the length of short arm between pivot joint centres.

In a preferred form the engagement means comprises a protrusion from the end of the sash mounting member and the co-operable engaging means comprises a recess into which the protrusion engages as the stay reaches its fully closed position.

Preferably the length of the short arm between pivot joint centres is between one third and three quarters of the length of the long arm between pivot joint centres.

e C c e c e c e e C e e c e Any suitable form of friction pivot joint may be used with the window stay of the invention. A suitable form of friction pivot joint is for example described in my cognate New Zealand patent specification 212599/213772 which is incorporated herein by reference for description of this friction pivot joint. This pivot joint has a hollow centre which allows screws for fixing the stay to a window frame (or sash) to be screwed through the pivot joint, so that loads are taken directly at the ends of the stay arms.

The stay is suitable for use in both awning and casement applications. With the stay of the invention when the window is closed the stay is also fully closed ie the sash and frame mounting members and long arm are fully aligned. This allows the stay to be used with common standard uPVC window profiles. Also, in initial opening the head of the window has a slight downward and then an outward movement (the stile of the sash moves sideways then outward in the case of a casement window). This enables the stay to employ an integral head locking mechanism, if desired. The sash mounting points of the stay may be properly spaced apart giving good sash stability when the sash is open and the stay possesses a high degree of inherent strength.

BRIEF DESCRIPTION OF TIIE DRAWINGS

A preferred form of the friction stay of the invention is illustrated, by way of example, in the accompanying drawings, wherein: Figure 1 is a view of a preferred form window stay of the invention from one side in its fully extended or open position, Figure 2 is a view of the stay of Figure 1 in its closed position, and Figure 3 is an end view of the preferred form stay in the direction of arrow A in Figure 2.

DESCRIPTION OF PREFERRED FORM

Referring to Figures 1 to 3 the preferred form stay illustrated in the drawings comprises a short arm 1 and a long arm 2. The arms are preferably formed from stainless steel or c.e ie: e. :: ::À.

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could alternatively be formed of aluminium, for example. The frame ends of the short and long arms 1 and 2 are pivotally connected to a frame plate 3 for securing to the frame of a window, by way of suitable friction pivot joints 4 and 5 as will be further described.

The sash ends of the short arm 1 and long arm 2 are pivotally connected to a sash plate 6 for securing to the sash of the window, by way of similar pivot joints 7 and 8 which are preferably also friction pivot joints. The sash plate and frame plate 3 may be formed from stainless steel or aluminium for example but could alternatively be by injection moulding from a plastics material such as acetyl or other self lubricating and wear resistant synthetic material.

The short arm-frame plate pivot joint 4 is offset from the longitudinal centreline of the frame plate 3 in one direction and the long arm-frame plate pivot joint 5 is offset in the other direction. When the stay is closed as shown in Figure 2, the frame-plate 3 and sash plate 6 are aligned. The short arm 1 extends at an angle from the short arm-sash plate pivot joint 7 to the offset pivot joint 4 as shown. The long arm extends at an angle from the long arm-sash plate pivot joint to the offset pivot joint 5. In terms of dimensions, in typical sizes of stays in common use, the short arm-frame plate pivot joint is preferably offset from the centre use of the frame plate by between 2 and 20 mm and most preferably between 5 and 10 mm, and the long arm-frame plate pivot joint is offset by between 2 and 20 mm and most preferably between 5 and 10 mm. The angles between the short arm and the frame mounting member and the long arm and the frame mounting member when the stay is closed are preferably between 5 and 10 degrees and most preferably about 7 degrees.

It is preferred that the long arm is connected to the frame mounting member eccentrically of the end of the long arm as shown, and that the short arm is also connected to the frame mounting member eccentrically of the end of the short arm as shown.

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The offsetting of at least the long arm-frame plate joint 5 and preferably also both the short arm-frame plate pivot joint 4 and long arm- frame plate pivot joint 5 enables the stay to be fully closed so that the frame plate 3 and sash plate 6 are substantially aligned when the stay is in its closed position, in comparison to conventional four bar stays where, even when the window sash and stay are in their closed positions, the geometry of the stay is not fully closed is the long arm and sash mounting member are not aligned as shown in Figure 2 (with the stay of the invention) but are still a few degrees away from this position. Another advantage of the stay of the invention is that when the stay is within about 10 degrees of its closed position, the window sash will tend naturally to spring shut. This is in contrast to the conventional four bar stay geometry, wherein when the window is closed but not latched shut, the stay and sash tend to spring to a slightly open natural position of rest.

Each of the frame and sash plates 3 and 6 may be provided with suitable mounting holes whereby the stay may be mounted to a window frame and sash in use. When the pivot joints employed are of the preferred form type described herein the frame and sash plates 3 and 6 can additionally or alternatively be secured to the frame and sash by screws or like fasteners passing through the hollow centres of the pivot joints themselves. This is advantageous, particularly in casement window applications, as the frame plate is secured to the frame at the same point that loads are applied so that deformation ofthe frame plate is minimised.

In use the stay can be moved from its fully extended or open position shown in Figure 1 wherein the sash plate 6 and a sash mounted thereto (sash not shown) extend at an angle to the window aperture, to or towards its closed position (or vice versa) by pulling (or pushing) on handles suitably mounted to the window sash. The stay of Figure 1 is shown in its closed position in Figure 2, and the movement of the sash plate/short arm, sash plate/long arm pivot joints is as indicated by arrows Y and Z in Figure 1. During the last part of the closing movement of the stay the good "pull in" is provided.

The preferred form of stay shown in the drawings also incorporates a preferred form of head locking mechanism. The top end of the sash plate 6 is formed with an engagement e e : :: : À means in the form of a protrusion 12 (see Figure 1). A recess 13 is formed in an integral enlarged head 14 of the frame plate 3. When the window stay is closed, the sash plate 6 will move such that the protrusion 12 engages into the recess 13 as shown in Figure 2. When the stay is fully closed and the protrusion 12 is fully engaged into the recess 13, the head of the window is locked and cannot be opened by force or prising open between the top of the window sash and the window frame.

Other forms of interlocking engagement means on the sash plate and cooperable engaging means on the frame plate are possible. For example, the respective positions ofthe protrusion and recess could be reversed. The distance between the short arm-sash plate pivot joint 7 and the protrusion 12 on the end of the sash plate is less than two thirds, and very preferably less than one half, of the length of the short arm, between centres of the pivot joints 4 and 7, to ensure propa operation of the head locking mechanism.

The foregoing describes my invention including a preferred form of friction pivot joint, and various alterations and alternatives. Other alterations and modifications as will be apparent to those skilled in the art are intended to be incorporated within the scope hereof as defined in the following claims.

Claims

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1. A friction window stay for mounting a window sash in a window frame, the stay including: a frame mounting member for securement of the stay to the frame of a window, a sash mounting member for securement of the stay to the sash of a window, a short arm having a pivot joint between a sash end of the short arm and the sash mounting member and a pivot joint between a frame end of the short arm and the frame mounting member, and a long arm having a pivot joint between a sash end of the long arm and the sash mounting member and a pivot joint between a frame end of the long arm and the frame mounting member which is offset to one side of a longitudinal centreline of the frame mounting member such that when the stay is fully closed, so that the sash mounting member and frame mounting member are substantially aligned, the long arm extends at an angle relative to the longitudinal centre line of the frame mounting member, from the long arm-sash mounting member pivot joint to the offset long armframe mounting member pivot joint.

2. A friction window stay according to claim 1 wherein the short armframe mounting member pivot joint is offset to the opposite side of said longitudinal centre line of the frame mounting member than said offset long arm-frame mounting member pivot joint, such that when the stay is fully closed the short arm extends at an angle relative to the longitudinal centre line of the frame mounting member, from the short armsash mounting member pivot joint to the short arm-frame mounting member pivot joint.

3. A window stay according to either of claims 1 and 2 wherein the frame mounting member has a substantially constant width over its length.

4. A window stay according to claim 3 wherein the frame mounting member is formed of strip material.

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5. A window stay according to any one of claims 1 to 4 wherein the long arm is connected to frame mounting member eccentrically ofthe end ofthe long arm.

6. A window stay according to any one of claims 1 to 5 wherein the short arm is connected to frame mounting member eccentrically of the end of the short arm.

7. A window stay as claimed in any one of claims 1 to 6, comprising an engagement means on a short arm end of the sash mounting member which interlocks with a co- operable engaging means on the frame mounting member to lock the head of a window mounted by the stay against forced opening when the stay is fully closed.

8. A window stay as claimed in claim 7, wherein the engagement means on the end of the sash mounting member comprises a protrusion from said end of the sash mounting member and the co-operable engaging means on the end of the frame mounting member comprises a recess to receive said protrusion, the protrusion being arranged to engage into the recess as the stay reaches its fully closed position.

9. A window stay according to claim 7 or claim 8 wherein the distance between the short arm-sash mounting member pivot joint and said engagement means on the end of the sash mounting member is less than two thirds of the length of the short arm between pivot joint centres.

10. A window stay according to claim 7 or claim 8 wherein the distance between the short arm-sash mounting member pivot joint and said engagement means on the end of the sash mounting member is less than one half of the length of the short arm between pivot joint centres.

11. A window stay as claimed in any one of claims 1 to 10, wherein the angle between the short arm and the centreline of the frame mounting member when the stay is closed is between 5 and 10 degrees. À

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12. A window stay as claimed in any one of claims 1 to 10, wherein the angle between the short arm and the centreline of the frame mounting member when the stay is closed is substantially 7 degrees.

13. A window stay as claimed in any one of claims 1 to 12, wherein the angle between the long arm and the centreline of the frame mounting member when the stay is closed is between 5 and 10 degrees.

14. A window stay as claimed in any one of claims 1 to 12, wherein said angle between the long arm and the centreline of the frame mounting member when the stay is closed is substantially 7 degrees.

15. A window stay as claimed in any one of claims 1 to 14, wherein the short arm- frame mounting member pivot joint is offset from said centreline of the frame mounting member by between 3 and 20 mm, measured between said centreline and the centre of the offset pivot joint.

16. A window stay as claimed in any one of claims 1 to 14, wherein the short arm- frame mounting member pivot joint is offset from the centreline of the frame mounting member by between 5 and 20 mm, measured between said centreline and the centre of the offset pivot joint.

17. A window stay as claimed in any one of claims 1 to 16, wherein the long arm- frame mounting member pivot joint is offset from said centreline of the frame mounting member by between 3 and 20 mm, measured between said centreline and the centre of the offset pivot joint.

18. A window stay as claimed in any one of claims 1 to 16, wherein the long arm- frame mounting member pivot joint is offset from said centreline by between 5 and 30 mm, measured between said centreline and the centre of the offset pivot joint.

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19. A window stay as claimed in any one of claims 1 to 18, wherein the frame mounting member, sash mounting member, short arm and long arm are all formed from stainless steel.

20. A window stay according to any one of claims 1 to 19 wherein the pivot joints between the frame mounting member and each of the arms of the stay have a hollow centre to allow screws for fixing the stay to a window frame and window sash to be screwed through the pivot joints.

21. A window stay substantially as herein described with reference to the accompanying drawings.