GB2407124A

GB2407124A - Sash window locking means

Info

Publication number: GB2407124A
Application number: GB0324399A
Authority: GB
Inventors: Alan David Burgess
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-10-18
Filing date: 2003-10-18
Publication date: 2005-04-20
Anticipated expiration: 2023-10-18
Also published as: GB0324399D0; GB2407124B

Abstract

The present invention provides a sash window assembly with an outer frame adapted for fitting to a window opening in a building, and first and second window panels (21, 22) mounted on the outer frame. At least one panel is slidable with respect to the other and to the outer frame so that the window may be opened. In addition, a pair of spaced locking cams (11, 12) are provided on one panel and each cam is engageable with a respective keep (23) on the other panel. One cam (11) is arranged for clockwise rotation to engage with one keep (23), and the other cam (12) is arranged for counter-clockwise rotation to engage with the other keep (23).

Description

1 24071 24 Sash Window Lockina Means This invention relates to locking

means for a sash window assembly, and to sash window assemblies incorporating such locking means.

Sash windows are widely used in both domestic dwellings and offices, in view of the aesthetic appearance of a building having such windows.

Typically, a sash window assembly consists of an outer frame secured to a window opening in a building, within which frame are provided a pair of window panels, mounted for relative sliding motion such that either one or both panels may be slid so as partially or wholly to overlap the other, thereby opening the window. Most commonly, the panels are arranged for vertical sliding motion, with the lower panel mounted inwardly of the upper panel.

Sash window assemblies may be formed either with both panels slidable within the frame, or with one panel fixed to the frame.

Each slidable panel is generally provided, at either side thereof, with a balancer, arranged to transfer at least some of the weight of the panel to the frame, thereby to facilitate opening of the window and maintenance of the panel in an open or closed position. The sash window assembly typically also includes draught excluding strips or seals provided between the frame and the sliding panels, and locking means to prevent relative movement of the two panels when the window is closed. The locking means may desirably also include a lock to prevent unauthorized opening of the window.

A commonly used locking means for sash windows is the so-called cam locking assembly. This involves the provision on one panel of a cam, which is arranged to engage with a keep provided on the other panel by rotating about an upstanding pivot secured to said one panel. Most - 2 commonly, the cam has a helically-formed ramp extending partially therearound, said ramp being inclined in one direction (for example clockwise). With the panels in their closed position, the cam is rotated in the opposite direction (therefore counter-clockwise) so as to engage a protruding arm of the keep, with the ramp. Further rotation of the cam in this direction urges the keep arm towards the higher end of the ramp, thus urging the panels away from one another and into closer registration with the outer frame, thereby to ensure efficient closure of the window. Cams wherein the panels are urged together horizontally are also known, and in these a curved projection on the rotating cam, which projection locates behind the keep thus pulling it toward the cam.

Despite the widespread use of such cam locking mechanisms as described above, there are several drawbacks associated with their use.

Each of these drawbacks stem from the usual practice of providing a sash window with one or more cams, each formed with the ramp or other cam mechanism orientated in one direction only. To reduce tooling and manufacturing costs, manufacturers have previously used only one cam or if more than one was used both had had the same direction of rotation (or handedness), e.g. with the ramp inclined in a clockwise direction (referred to herein as a "right-handed" cam, since a user must turn the cam to the right in order to engage it with the keep) or an anticlockwise direction (referred to herein as a "left-handed" cam).

One drawback associated with the use of single directional cams as described above is that the action of rotating the cam pushes the panels laterally into one or other side of the frame. This can cause overcompression of the draught seal at that side of the frame, and an increased gap leading to under-compression of the draught seal at the opposite side of the frame. This is detrimental to the performance of both seals and is likely to decrease their useful lifetime.

A second drawback arising from the use of single directional cams is that they pose a potential security risk. Repeated forcing of one panel to one side can decrease the level of engagement between the cam and its keep, thus rendering the sash window vulnerable to forced entry.

The present invention seeks to address the above-identified issues by providing a sash window assembly with both a left-handed and a righthanded cam. That is to say, one cam which engages with its respective keep by rotation in a clockwise direction, and one cam which engages with its respective keep by rotation in a counter-clockwise direction.

Therefore, according to a first aspect of the present invention, there is provided a sash window assembly comprising an outer frame adapted for fitting to a window opening in a building, first and second window panels at least one of which is slidable with respect to the other and to the outer frame so that the window may be opened and a pair of spaced cams provided on one panel and each engageable with a respective keep on the other panel, one cam being arranged for clockwise rotation to engage with one of the keeps, and the other cam being arranged for counter-clockwise rotation to engage with the other of the keeps.

Preferably, the pair of cams comprises a left-handed cam and a right handed cam. That is to say, one cam engaging with the keep by rotation in a clockwise direction and the other cam engaging with its keep by anti - 4 clockwise rotation. In one specific embodiment such a pair of cams would comprise: one cam having a helically-formed ramp inclined in a counterclockwise direction, thereby to engage with its respective keep by rotation in a clockwise direction (the left-handed cam); and one cam having a helically formed ramp inclined in a clockwise direction, thereby to engage with its respective keep by rotation in a counter-clockwise direction (the right-handed cam).

Most preferably, each cam is adapted to be rotated by the application of a manual force. A thumb plate or handle extending from the main body of the cam is preferably provided for this purpose.

Each cam may also desirably be provided with a lock to maintain said cam in engagement with its respective keep. The lock acts to prevent unwanted rotation of each cam about its pivot.

In addition to the sash window assembly according to the first aspect of the present invention as hereinbefore described, it is envisaged that the left- handed and right-handed cams of the present invention may also be supplied separately for retro-fitting to existing sash window assemblies.

Therefore, according to a second aspect of the present invention, there is provided locking means to prevent relative opening movement of a pair of panels of a sash window assembly, comprising a pair of cams adapted for mounting on a first panel of a sash window assembly, and a pair of keeps adapted for mounting on a second panel of said sash window assembly, wherein one cam is arranged for clockwise rotation so as in use to engage with one of the keeps and the other cam is arranged for counter- clockwise rotation so as in use to engage with the other keep. - 5

In order that the present invention may be fully understood, a preferred embodiment thereof will now be described in detail, though only by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a pair of left-handed and right-handed cams, for use in the present invention; Figure 2 shows an exploded view of part of a sash window assembly, according to the present invention; and Figure 3 shows the sash window assembly of Figure 2, in a closed position.

10Referring first to Figure 1, there is shown a pair of cams, comprising a left-handed cam 11 and a right-handed cam 12. Each cam 11,12 has a main body portion 13 mounted on a base plate 14, which is adapted to be secured to a lower panel of a sash window assembly, as will be described in more detail subsequently with reference to Figures 2 and 3. An upstanding pivot 15 15extends from each base plate 14 through an aperture 16 in the main body 13 of each cam 11,12. A thumb plate 17 is provided on each cam 11,12, by means of which a manual force can be applied so as to cause the cam 11,12 to rotate about its respective pivot 15.

The main body 13 of each cam 11,12 is partially surrounded by an outer sleeve 18 defining a helically-formed ramp surface 19, adapted so as in use to engage with a keep (not shown) provided on an upper panel of a sash window assembly, as will be described in more detail subsequently with reference to Figures 2 and 3.

As can be seen from Figure 1, in the left-handed cam 11, the ramp surface 19 is inclined in a counter-clockwise direction, as indicated by arrow a. - 6

In use, this enables the left-handed cam 11 to engage with its respective keep (not shown) when the cam 11 is rotated in a clockwise direction, as indicated by arrow b.

Conversely, in the right-handed cam 12, the ramp surface 19 is inclined in a clockwise direction, as indicated by arrow c. In use, this enables the right-handed cam 12 to engage with its respective keep (not shown) when the cam 12 is rotated in a counter-clockwise direction, as indicated by arrow d.

Referring now to Figures 2 and 3, there is shown a sash window assembly provided with the left-handed and right-handed cams 11,12 described above with reference to Figure 1. The sash window assembly comprises a lower panel 21 and an upper panel 22, each mounted for vertical sliding motion in an outer frame (not shown) which can be secured to a window opening in a building, the lower panel 21 being disposed inwardly of the upper panel 22. For convenience, the outer frame of the sash window assembly is not shown in Figures 2 and 3, but would be of a standard generally rectangular configuration with channels in the jambs to guide the vertical sliding movement of the panels 21 22.

As can be seen best from Figure 2, the left-handed and right-handed cams 11,12 are provided on an upper part of the lower panel 21, whist a lower part of the upper panel 22 carries thereon a pair of keeps 23 in vertical alignment with the cams11, 12. Each keep 23 has an arm 24 protruding therefrom, adapted to engage with the ramp surface 19 carried on each cam.

To enhance the engagement between the cams 11, 12 and their respective keeps 23, the keep arms 24 may additionally be provided with a lip adapted to 2s be received in a groove provided behind the ramp surface of the cam.

In order to close the sash window, the panels 21,22 are first moved to their closed positions, such that each cam 11,12 is brought into horizontal, as well as vertical, alignment with its respective keep 23. The left-handed cam 11 is then rotated in a clockwise direction, as indicated by arrow b, whilst the right-handed cam 12 is rotated in a counter-clockwise direction as indicated by arrow d. In each case, the rotation can be effected by the application of a manual force to the thumb plates 17. A further advantage of the present invention is that both these actions can be done simultaneously because, with the right-handed cam on the right hand side and the left-handed cam on the other side, a person can conveniently operate both with a natural hand action.

This means that unlike the prior art the provision of two cams according to the present invention does not the increase complication or delay in closing or opening the window.

The closed position thus achieved is shown in Figure 3. The cams 11,12 have now been rotated such that the ramp surfaces 19 thereof engage with the keeps 23 (not visible in Figure 3), whilst the thumb plates 17 are now disposed outwardly of the cams 11,12. To open the window, the previously described operation is reversed: i.e. the left-handed cam 11 is rotated in a counter-clockwise direction, as indicated by arrow d, whilst the right-handed cam 12 is rotated in a clockwise direction, as indicated by arrow b. Again, both rotations are effected by the application of a manual force to the thumb plates 17. The panels can now be slid vertically such that they overlap. - 8

Claims

Claims 1. A sash window assembly comprising an outer frame adapted for

fitting to a window opening in a building, first and second window panels at least one of which is slidable with respect to the other and to the outer frame so that the window may be opened and a pair of spaced cams provided on one panel and each engageable with a respective keep on the other panel, one cam being arranged for clockwise rotation to engage with one of the keeps, and the other cam being arranged for counter-clockwise rotation to engage with the other of the keeps.
2. A sash window assembly as claimed in claim 1, wherein the pair of cams comprises a left-handed cam and a right-handed cam.
3. A sash window assembly as claimed in claim 2, wherein the left- handed cam is located on the left side of the one panel and the right- handed cam is located on the right side of the one panel.
4. A sash window assembly as claimed in claim 1, 2 or 3, wherein each cam has a helically formed ramp surface engageable with an arm on the associated keep.
5. A sash window assembly as claimed in claim 4, wherein one cam has a helically-formed ramp surface inclined in a counter-clockwise direction so as no in use to engage with the arm of its respective keep by rotation in a clockwise direction, and the other cam has a helically-formed ramp surface inclined in a clockwise direction so as in use to engage with its respective keep by rotation in a counter-clockwise direction. - 9 -
6. A sash window assembly as claimed in claim 4 or claim 5, wherein each cam has a groove formed behind the ramp surface, said groove being adapted to receive a lip on the keep arm.
7. A sash window assembly as claimed in any of the preceding claims, wherein each cam is adapted to be rotated by the application of a manual force.
8. A sash window assembly as claimed in any of the preceding claims, wherein each cam is provided with a lock to prevent unwanted rotation of the cam.
9. A sash window assembly as claimed in any of the preceding claims, wherein each cam has a base plate secured to said one panel, and a pivot upstanding from the base plate, about which the cam is rotatable.
10. A sash window assembly as claimed in claim 1 and substantially as herein described with reference to and as illustrated in the accompanying 1s drawings.
11. Locking means to prevent relative opening movement of a pair of panels of a sash window assembly, comprising a pair of cams adapted for mounting on a first panel of a sash window assembly, and a pair of keeps adapted for mounting on a second panel of said sash window assembly, wherein one cam is arranged for clockwise rotation so as in use to engage with one of the keeps and the other cam is arranged for counter-clockwise rotation so as in use to engage with the other keep.
12. Locking means as claimed in claim 11, wherein one cam is a lefthanded cam and the other cam is a right-handed cam. -
13. Locking means as claimed in claim 11 or claim 12, wherein each cam has a helically-formed ramp surface engageable with an arm on its respective keep.
14. Locking means as claimed in claim 13 wherein one cam has a helicallyformed ramp surface inclined in a counter-clockwise direction, so as in use to engage with its respective keep when rotated in a clockwise direction, and the other cam has a helically-formed ramp surface inclined in a clockwise direction so as in use to engage with its respective keep when rotated in a counter-clockwise direction.
15. Locking means as claimed in claim 13 or claim 14, wherein each cam has a groove formed behind the ramp surface, said groove being adapted to receive a lip on the keep arm.
16. Locking means as claimed in any of claims 11 to 15, wherein each cam is adapted to be rotated by the application of a manual force.
17. Locking means as claimed in any of claims 1 1 to 16, wherein each cam is provided with a lock so as in use to prevent unwanted rotation of said cam.
18. Locking means as claimed in any of claims 11 to 17, wherein each cam has a base plate adapted for securing to a panel of a sash window assembly, said base plate having an upstanding pivot, about which the cam is rotatable.
19. Locking means as claimed in claim 11 and substantially as herein described with reference to and as illustrated in the accompanying drawings.