NZ740480B2 - A window fastener - Google Patents

Abstract

window fastener (1) comprising: a base (2), configured for connection to the moveable sash of a window; a flap (3) pivotally connected to the base (2); wherein the base (2) and flap (3) are configured and connected so that the flap (3) can rotate between a closed position and an open position; the base (2) and flap (3) further configured and connected so that the flap (3) can pivot a substantial angle past the closed position, away from the open position. In the prior art, window fasteners or catches had the disadvantage that if the handle is not rotated sufficiently to allow the flap to rotate fully horizontal, the inner end of the flap can fail to clear the upper edge of the base of the window frame. The present invention provides an improved window fastener or spring to attend to this problem. base (2) and flap (3) further configured and connected so that the flap (3) can pivot a substantial angle past the closed position, away from the open position. In the prior art, window fasteners or catches had the disadvantage that if the handle is not rotated sufficiently to allow the flap to rotate fully horizontal, the inner end of the flap can fail to clear the upper edge of the base of the window frame. The present invention provides an improved window fastener or spring to attend to this problem.

Description

A WINDOW FASTENER FIELD The present invention generally relates to window fasteners. More particularly, but not solely, embodiments relate to a wedgeless window fastener and a spring for a window fastener.

BACKGROUND Wedgeless window fasteners (also known as wedgeless fasteners) are used in aluminium joinery for domestic and commercial windows. These fasteners are designed to be affixed to the sash of an awning or casement type window. The sash is an inner moveable section of a window assembly which has an outer stationary frame mounted in a wall aperture or similar. The sash is usually pivotably mounted near the top (or the side for a casement window) of the window frame to allow opening and closing of the window. In this type of window, the fastener or catch is usually located on the bottom or side of the sash. However, the window fastener can be located according to the requirements of the application and type of window. The fastener may be used with other types of windows or various openings. In some applications two fasteners are installed on a single sash.

These types of fasteners generally rely on a moveable flap that pivots around the lower inner edge of the window fastener between a vertical (closed) position that overlaps the inner edge of the window frame, and a horizontal position where the flap (and the body of the fastener) can pass over the top or inner edge of the bottom side of the frame. The flap is secured in the downwards or vertical position by a catch that extends across the inner side of the flap to hold it in position. Generally, the catch forms an integral part of a pivoting handle that is rotated to move the catch into and out of position. The flap is usually biased towards the open or upright or generally horizontal position by a spring or similar within the window fastener.

In these types of catches, if the handle is not rotated sufficiently to allow the flap to rotate fully horizontal, the lower, inner end of the flap can fail to clear the upper, outer edge of the bottom side of the frame as the sash is pulled closed, and can strike against the frame, potentially damaging the frame, the sash and the catch.

Prior art attempts to solve this may include providing more robust flap or attachment mechanisms, but this adds to cost and can be aesthetically detracting.

The present invention may provide an improved window fastener or spring, or may at least provide the public or industry with a useful choice.

SUMMARY According to one exemplary embodiment there is provided a window fastener according to claim 1.

According to another exemplary embodiment there is provided a window fastener according to claim 16.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings which are incorporated in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description of embodiments given below, serve to explain the principles of the invention, in which: Figure 1 is a perspective view from one side and above of a window fastener in the closed position according to an embodiment of the invention, showing a handle and a base unit with a cover; Figure 2 is an exploded view of the window fastener of Figure 1 from the same angle, showing detail of the base, a flap that is pivotally connected to the base and which is moved from an open or upright position to a closed or downwardly-extending position via rotation of the handle, a torsion spring located in the base, the base also having a receiving member or cam element with an outer surface with lobes spaced around the perimeter of the body of the member and extending along the body axially, which act to positively locate the handle into the open, closed and venting positions; Figure 3 is a front view of the window fastener in the closed position, looking directly outwards along the axis of rotation of the handle; Figure 4 is a side view of the window fastener in the closed position; Figure 5 is a front view of the window fastener in the open position; Figures 6a - 6f show the window fastener of the preceding figures, Figures 6a - c showing front views from the inside of the window looking at the window fastener in the closed, open, and open with the flap bent outwards past the closed position, and Figures 6d - 6f showing cutaway side views of the window fastener of Figures 6a - 6c respectively, showing detail of the interaction of the flap, spring and handle; Figure 7 is a perspective view from the side and above of the receiving member or cam element, showing detail of the outer surface and the rounded lobes; Figure 8 is a front view of the receiving member of Figure 7; Figure 9a is a front view of the base, showing detail of cut-outs in the base into which cylindrical extensions on the flap locate in use to hold the base and flap in a connected pivoting arrangement, and a pair of extensions onto which the wound portions of the torsion spring are located for assembly; Figure 9b is a rear view of the base of Figure 9a, showing detail of a seat into which the receiving member or cam element locates during assembly, with the receiving member rotating within the seat between a number of preferential positions as the handle is rotated; Figures 10a – 10e show the handle and receiving member rotating together between the sets of preferential positions of the seat; Figure 11 is a perspective view from the side and above of the flap of this embodiment of window fastener showing detail of the cylindrical extensions which locate in assembly and use into the cut-outs on the base; Figures 12a – 12f show the torsion spring of this embodiment of window fastener, Figures 12a - 12c showing perspective views from the side and above, and from the outside of the window looking inwards, of the spring, and Figures 12d - 12f showing side views of the spring of Figures 12a - 12c respectively, the spring formed as a pair of helically wound wire-formed central body elements, one end of the wire extending from each of the central body elements to form an unbroken loop that connects between the central body elements to hold the central body elements in a spaced-apart arrangement with a substantially common central axis, each of the central body elements locating onto the spring extensions shown in Figures 9a and 9b in use; Figures 13a – 13d are cross sections of the fastener in different states of use while mounted on the window, showing the sash and frame in corresponding positions; Figures 14a – 14d are projections of the flap; Figures 15a and 15b are enlarged projections of the cam element; Figure 16 is an exploded view of an alternative embodiment of the window fastener, showing detail of the base, a flap that is pivotally connected to the base and which is moved from an open or upright position to a closed or downwardly-extending position via rotation of the handle, a sheet spring located in a cartridge within this base, with the sheet spring biasing the flap to the open position, the cartridge also housing a receiving member or cam element with an outer surface having hollows spaced around the perimeter of the body and extending along the body axially, which act to positively locate the handle into the open, closed and venting positions; Figures 17a – 17c show front views from the inside of the window looking at the window fastener in the closed, open, and open with the flap bent outwards past the closed position, Figures 17d – 17f show the window fastener of Figures 17a - 17c showing cutaway side views of the window fastener, showing detail of the interaction of the flap, spring and handle; Figure 18a is a perspective view from the side and below of the cartridge and sheet spring, showing detail of the inserted sheet spring; Figure 18b is a perspective view from the side and below of the cartridge and sheet spring, showing detail of the removed sheet spring; Figure 19a is an exploded perspective view from one side and above of the cartridge, sheet spring, receiving member and base; Figure 19b is a perspective view from one side and above of the cartridge, sheet spring, receiving member and base; Figures 20a – 20j show the handle rotating between the set of preferential positions of the cartridge and receiving member for the alternative embodiment of the window fastener; Figures 21a and 21b are projections of the alternative embodiment of the flap; Figures 22a and 22b are enlarged projections of the alternative embodiment of the cam element; Figure 23 is a perspective back view from one side and above of the handle, washer and base; Figure 24a is a back view of a window fastener handle and button, having a venting configuration; Figure 24b is a cutaway side view of the window fastener handle and button of Figure 24a; Figure 25a and 25b are exploded and assembled views respectively of a further embodiment of a window fastener, showing detail of the base, a flap that is pivotally connected to the base and which is moved from an open or upright position to a closed or downwardly-extending position via rotation of the handle, a sheet spring located in a cartridge attached to this base, with the sheet spring biasing the flap to the open position, the cartridge also housing a receiving member or cam element with an outer surface having hollows spaced around the perimeter of the body and extending along the body axially, which act to positively locate the handle into the open, closed and venting positions; Figure 26a is a perspective view of a window fastener base according to an alternative embodiment, with a cartridge and sheet spring moulded in to form a single component; Figure 26b is an exploded view of a window fastener base according to an alternative embodiment, showing detail of the form of the cartridge and sheet spring; Figure 27a is a back view of a window fastener base according to an alternative embodiment; Figure 27b is a side view of a window fastener base according to an alternative embodiment; and Figure 27c is a front view of a window fastener base according to an alternative embodiment.

DETAILED DESCRIPTION A fastener 1 will now be described with reference to Figures 1 to 15. The fastener 1 is generally attached to the sash of an aluminium window.

The fastener 1 includes a base 2 and a handle 4 rotatable about the base 2. A flap 3 extends from the base 2, and a cover 5 is provided over the base 2. The base 2 is designed to be affixed to the sash of an awning or casement type window. A torsion spring 6 biases the flap 3, the function of which will be described in detail below.

The base 2 has a main unitary body portion that in use is connected to the window sash via a pair of screw apertures 8 on each side of the base 2. A pair of cut-outs 9 is formed in the lower front of the base 2. A central aperture 10 is formed through the body of the base 2.

The rear of the base 2 has a hollow section into which the torsion spring 6 locates. A pair of extension members 11 extend inwards from each side of the hollow section. The extension members 11 are short cylindrical extensions with a common axis that is perpendicular to the axis of the central aperture 10 (i.e. the axis of the extension members extends across the body). They can also be termed axle or spring mounts.

The flap 3 is a generally planar unitary body having roughly the same width as the base 2, with a flat outer side (i.e. the side facing out of the room). A pair of pins 12 extends from the upper edge, having a common axis aligned generally with the lower inner edge of the base 2. When the window fastener 1 is assembled, the pins 12 locate into the cut-outs 9.

The pins 12 form an axis of rotation for the flap 3 around the lower inner edge of the base 2. The inner side of the flap 3 (i.e. facing into the room) has angled side portions and a flat centre portion, so that the centre portion is thicker (inner to outer face) than the side edges of the flap 3.

The flap 3 is shown in more detail in Figures 14a – 14d. Figure 14b is an enlarged view of the region marked B in Figure 14a. In particular there is an envelope or pocket 23 provided for the free ends 16 of the torsion spring 6. This may be used to limit any wearing damage to the flap 3 or frame from the free ends 16 over time. The cover 5 slides over the base 2 and flap 3 to hold the pins 12 in position in the cut-outs 9.

The flap 3 can rotate between open, closed and abuse positions. Figures 13a to 13d show the fastener 1 in a variety of different positions. In Figure 13a the sash 136 is closed with the flap 3 engaged with the frame 100. In Figure 13b the sash 136 is open. In Figure 13c the sash 136 is in the venting position with the extension 4c engaged with the frame 100. In Figure 13d the flap 3 has been bent backwards (the abuse position) due to the sash 136 being closed while the flap 3 is in the closed position. In this position the flap 3 contacts the bottom inside corner 136’ of the sash extrusion, as can be clearly seen in Figure 13d. This prevents further pivoting of the flap 3. Further, the flap is sandwiched between the frame and that point of contact with the bottom inside corner 136’ of the sash, which acts to provide a degree of support to the flap 3, thereby helping to prevent damage. In the position of Figure 13d, contact with the window frame therefore tends to push the flap against the window sash and the base 2, which act together to support the flap and prevent damage. In some applications the flap may contact a higher point on the inside face of the sash extrusion.

The open position is also shown in Figure 5 where the flap 3 is aligned upright or generally horizontal and extends inwards from the base 2. It can be seen that in this position, the flap 3 is clear of the outer face of the base 2 - that is, no part of the flap 3 extends below the lower edge or surface of the base 2 to potentially interfere with movement of the sash relative to the frame. In the open position, the flap 3 is at a minimum angle of 90 degrees to the base 2. The maximum angle of the flap 3 to the base 2 in the open position may be approximately 105 degrees.

When the flap 3 is in the closed position, the flap 3 extends generally vertically downwards from the base 2, as shown in Figures 3 and 4, that is, beyond the lower edges or the general plane of the lower or outer face of the base 2. In the closed position, the flap 3 is typically at a zero degree angle to the base 2, i.e. parallel to the base 2. This is preferred as it gives an adequate weather tight seal and the cosmetic appearance of linear alignment between the fastener and the window sash and/or frame. If the window allows for an adequate weather tight seal to be obtained at an angle other than zero degrees, the flap 3 may be at a lesser or greater than zero degree angle to the base 2 in the closed position.

The flap pins 12 and cut-outs 9 are shaped and sized so that the flap 3 can rotate backwards from the closed position towards the underside or outer face of the base 2 a substantial distance or angle past the closed position. In preferred embodiments the flap can rotate around 15 to 45 degrees past the closed position, preferably around 20 to 30 degrees past the closed position. In preferred embodiments, motion of the flap is limited by contact with the window sash, as shown in Figure 13d.

In a typical window fastener, if an attempt is made to close the window with the flap 3 in the closed position, resulting in the abuse situation of Figure 13d, damage may occur. The typical solution to this problem is to have a robust flap 3, which uses a significant amount of material. In the present invention, the flap 3 construction and spring 6 design allows the flap to bend back past the closed position, absorbing the impact of the window frame on the flap 3. The use of plastics materials is preferred as its ability to deform also assists with shock absorption and reduces damage to the window frame or the rubber seal commonly used with aluminium windows. However even if the flap 3 were to be constructed of a material that deforms less readily, such as a metal or metal alloy, then the additional movement allowed in this shock absorbing design would assist in reducing the damage caused to the fastener 1. As such, this design allows for an increased range of suitable materials.

In the applicant’s previous New Zealand patent 554172, the content of which is herein incorporated by reference, the wedgeless window fastener does not contain a spring. Instead the rotation of the flap is limited by a shoulder on the base, preventing rotation past zero degrees into the abuse position. If an attempt was made to force the fastener into the abuse position from the closed position, then either the base or the flap may be damaged. A pair of washers drives and holds the flap in the open position, and if an attempt was made to force the flap into the closed or abuse position from the open position, these washers, the base or the flap may be damaged. The flap may be able to withstand some of these abuse cycles, but as more damage occurs, it is more likely to get into the abuse position as it will have deformed. In the present invention, if the flap is undesirably forced into the closed or abuse position, the rotation would be allowed and spring is simply further loaded, preventing damage to the flap.

When the forcible rotation is ceased, the spring would relax and the flap rotate back to the intended position. The flap and the handle are also able to move independently, reducing the likelihood of damage to the cam element, and allowing free movement of the flap into the position of Figure 13d, independent of the handle.

The force that would cause failure of the previous fastener is approximately 15N, which is the force that would cause the flap to start deforming. The present invention has a different point of failure, as the flap does not deform. This point of failure occurs when an attempt is made to pull the handle off the base after the window is completely closed. This requires over 600N of force, a much greater amount than that of the previous fastener.

It should also be noted that open and closed positions at different angles are possible. For example, the flap 3 open position at rest could be with the flap 3 angled upwards - i.e. rotated upwards past the position shown in Figure 5. The closed position could be downwards at an angle - e.g. 45 degrees - rather than vertically downwards, depending on the shape of the window frame with which the flap 3 engages in use.

A receiving member or cam element 7 locates into a hollowed-out seat 18 at the rear of the base 2, and is held in place by a screw 13 or similar passing from the rear through a central aperture in the cam element 7, and screwing into a connection extension 4a on the handle 4, which has an aperture (not shown) to receive the screw 13. The outer surface of the cam element 7 has a series of lobes 22 (Figure 8), making it roughly square when viewed end-on, with slightly outwardly curved sides, and rounded corners, the lobes 22 extending along the body in line with the axis of the central aperture. These lobes 22 may alternatively be spaced around an inner surface. It can be seen in Figures 7 and 8 that cut-out or hollow sections 14 are formed in the cam element 7 towards the lobes, allowing deformation of the cam element 7.

The hollow rear seat area 18 is generally circular, as shown in Figure 9b, with a bottom opening. The side wall of the seat area 18 includes curved indentations 19, into which the lobes 22 locate as the cam element 7 moves between positions. These indentations 19 may also be spaced around an outer surface.

In use, with the handle 4 connected, a user can manipulate the handle 4, which causes rotation of the cam element 7. The hollow rear seat area 18 of the base 2 is shaped and sized so that as the cam element 7 rotates within the hollow rear seat area 18, the lobes 22 will come into interference contact with the closer inner sides 38 of the hollow rear seat area 18, and resist further turning due to compression of the lobes 22. With the application of slightly more force the lobes 22 will move past this point so that the cam element 7 'jumps' to the next indentation 19.

It can be seen that the handle 4 (and cam element 7) will be biased towards certain positions and orientations due to this interference. These correspond to the open, as shown in Figure 10c, venting, as shown in Figure 10e, and closed, as shown in Figure 10a, positions. The handle 4 positively locates to these positions, and resists moving away from these positions until sufficient force is applied to overcome the interaction of the lobes 22 with inner sides 38 and cause it to move to the next position.

The deformation is shown in more detail in Figure 15. Figures 15a and 15b show the cam element 7 in a compressed state, at 45 degrees between the open and venting positions. Here, three of the lobes 22 are compressed. This can be seen by comparison of Figure 15a with the uncompressed state of the cam element as shown in Figures 7 and 8.

Approximately 0.5mm of compression (or interference depth) is provided in this and the other intermediate positions between the closed, open and venting positions. The bridge members, located between the lobes 22 and the central portion of the cam element 7, are approximately 1.5mm thick.

In use isolated from the torsion spring, the operator rotates the handle away from one of the neutral closed, open, or venting positions. When the handle is moved beyond an eighth of a turn or beyond the maximum feel of the contact force between the cam and cooperating hollows, the handle will tend to spring forward another eighth of a turn into the next neutral position. If the handle is rotated less than an eighth of a turn, then the handle will tend to spring back to the neutral position it came from. If the handle is rotated exactly an eighth of a turn, its momentum should carry it to the next neutral position. Preferably the handle will not rest between the neutral positions. Preferably the shapes of the cam and hollows in this embodiment are symmetrical, which means that the forces are the same in a clockwise or anti-clockwise direction.

As the fastener wears, the forces required to begin opening or closing it change. A typical range of forces may be 11N to open the fastener when it is new, to 2.5N when it is considered to be at the end of its useful life.

However different levels of force may apply depending on the requirements of the application.

The handle 4 also has extensions 4b and 4c, extending outwards radially from the axis of the connection extension 4a. As the handle 4 is moved to the 'closed' position, the extension 4b rotates downwards past the inner lower edge of the base 2, to push or rotate the flap 3 downwards and to hold it in this position.

It is possible that several types of modular handles may be compatible with this design. These may include left and right handed variants, low and high profile variants, and handles having a venting extension 4c as well as extension 4b. Combinations of these options are also possible, as well as additional modular handle types.

The handle extension 4c has a shallow pocket to receive a button 20, in the case when the window fastener has a venting extension 4c. The button 20 is the only part of the window fastener 1 which makes contact with the frame 100 when the fastener 1 is in the venting position, with the intent that the material that button 20 is made of protects the frame 100 from damage. In previous window fasteners, this button 20 has been a self-adhesive silicone button sitting in a shallow pocket. The disadvantage of this is that it may be difficult to align and adhere, and may come unstuck if it does not adhere correctly. The button 20 may be a choking hazard to humans or animals if it comes unstuck and is swallowed.

Alternatively the button 20 may be moulded and pressed into a deeper pocket as shown in Figure 24. The rigid button and deeper pocket do not allow for the button to be incorrectly aligned. The moulded button is also cheaper to make than a silicone button and is less likely to fall out and become a choking hazard. The depth of the pocket may have a minimum of 2mm and preferably be 3mm.

The torsion spring 6 is also located in the hollow at the rear of the base 2, and acts on the flap 3 to bias the flap 3 upwards or towards the open position, the extension 4b pushing the flap 3 downwards against the force of the torsion spring 6.

Referring to Figures 12a to 12f, the torsion spring 6 comprises a pair of helically wound wire-formed central body elements 15 held apart and with a common axis. The central body elements 15 are held apart by a loop 17 of the wire that forms the central body elements 15, which extends from the outer end of one of the central body elements 15 in a loop to the outer end of the other central body element 15. The sides of the unbroken loop 17 extend beyond the outer ends of the central body elements 15. The free ends 16 of the wire extend away from the loop 17 to form an inner loop, aligned substantially perpendicularly to the unbroken loop 17 as shown in Figure 12a, when the torsion spring 6 is in an unstressed or rest position.

The torsion spring 6, having the double sided coil 15, allows for more even distribution of the load on the components. As a result, each coil is subjected to half the strenuous load a single spring would be, potentially allowing it to survive more operational cycles before failure, extending the life of the fastener. The double coil design is larger than typical single coil designs, and so is easier for the person assembling the fastener to pick it up, manipulate and assemble.

The preferred materials used in the construction of the fastener of Figure 2 are as follows. The handle 4, base 2 and cover 5 are made from either die cast zinc or injection moulded plastic. The washer 21, flap 3 and cam element 7 are made from plastic. The button 20 is made from rubber, plastic or resin. The torsion spring 6 is made from stainless steel and the screw 13 may be steel or stainless steel.

During assembly, the sides of the torsion spring 6 are pinched together (the central body elements 15 are pushed towards one another generally along their common axis), and the torsion spring 6 is located into the hollow area 18 at the rear of the base 2, the central body elements 15 slotting onto or sliding outwards onto the extension members 11. The torsion spring 6 is held in place by the force provided by the loop 17, which pushes the central body elements 15 outwards away from one another along their common central axis. This holds the central body elements 15 on the extension members 11, to hold the torsion spring 6 in place. The cam element 7 locates into the hollow area 18 so that the loop 17 of the torsion spring 6 is sandwiched between the base 2 and the cam element 7. It can be seen that the loop 17 is held in position when the fully assembled fastener 1 is in use, and that the free ends 16 of the wire that form the spring 6 will extend inwards along the rear face of the flap 3 to push the flap 3 inwards and upwards.

The window fastener 1 is connected to the moveable sash of a window on the opposite side to the window frame hinge or axis of rotation between the sash and frame. For example, if the sash pivots open from the top edge, the window fastener 1 will be located on the bottom or lower side of the sash. To lock the window, a user pulls the lower edge of the sash inwards to pivot it inwards and closed, and then rotates the handle 4 from the open position to the closed position. This causes extension 4b to rotate across the inner surface of the flap 3, across one of the angled side surfaces and then onto the flat surface on the inner side of the thicker central section. As the extension 4b passes across the inner surface of the flap 3, it pushes the flap 3 downwards. When the flap 3 is downwards in the closed position, the flap 3 acts against the inner surface of the frame to prevent the sash from rotating back outwards. The flap 3 rotates downwards against the torsion spring 6, specifically against the inner loop formed by the free ends 16 (in the closed position, the torsion spring 6 is aligned so that the outer loop 17 and the free ends 16 are generally parallel or in the same plane as shown in Figure 12b.

To open the window, a user rotates the handle 4 to the open position. The torsion spring 6 pushes the flap 3 back upwards, and the sash can be rotated or pushed outwards. In previously known fasteners of a similar type, if a user has the window open, but the handle (and flap) is not quite fully in the open position, then if a user attempts to pull the sash closed, the flap will be angled downwards slightly and damage can occur as this is pulled into contact with the outside of the frame. The window fastener 1 of the present invention helps to prevent this in several ways: firstly the flap 3 can rotate backwards past the closed position (vertically downwards in the embodiment described), absorbing the shock of the impact so that there is less likelihood of damage; secondly, the flap can preferably rotate into contact with the sash (as shown in Figure 13d), such that the sash supports the flap; and thirdly by having a handle connection where the handle 4 positively locates between positions as it is rotated, so there is less likelihood that the handle 4 will inadvertently be left in a position between fully open or fully closed. The biasing may also be useful in window fastener designs not requiring a flap.

In an alternative embodiment, a sheet spring 106 may be used instead of a torsion spring 6. The sheet spring 106 may be constructed from a single layer of sheet spring material, or several if required. An exploded view of this fastener can be seen in Figure 16. The overall function of the window fastener remains the same with this configuration. The flap 103 is biased towards the open position by the sheet spring 106 and the cam element 107 may bias the handle 104 to the open, closed and optionally venting positions.

One possible shape of the sheet spring 106 is shown in Figures 18a and 18b. It has a flat front face with a lengthened section 129 on the back face for reinforcing the bearing area. The edges may be rounded or the material folded back on itself to prevent wear on the parts that the edges come into contact with. The centre of the sheet spring 106 bending is around the central, lengthened section 129.

An alternative spring for this design may be a compression spring, having the same linear operating principle. The compression spring may be a hollow rubber cylinder. A tension spring may be used in the reverse way. It may be stretched when the flap is closed, and relaxed when the flap is pulled up.

The cartridge 126 is approximately U shaped and may hold the edges 130 of sheet spring 106 in the edge parallel to the upper edge of the flap 103.

Other appropriate holding configurations are possible, such as the back perpendicular edge 131. The insertion of the sheet spring 106 into the cartridge 126 is shown in Figures 18a and 18b. The sheet spring 106 may be over-moulded into the cartridge 126 to help with assembly, or they may be separate. The cartridge 126 also surrounds the cam element 107 and attaches to holes 127 in the base with dowel pins 125, as shown in Figures 19a and 19b.

The alternative embodiment of the base 102 has a central aperture 110 with sections of two different radii. The larger radius section 111 spans approximately six tenths of the circumference of the aperture 110. The attachment shaft 105 of the handle 104 has a single spline 133 spanning approximately one tenth of the circumference, as shown in Figure 23. The axis of the aperture 110 aligns with the axis of the handle shaft 105 to ensure that the handle 104 can only rotate between the closed, open and venting positions without allowing full rotation. The cartridge 126, sheet spring 106, cam element 107 and base 102 assembly are isolated in Figures 19a and 19b.

The flap 103 is continuous between the pins 112 with a wedge cam 122 in the centre of the continuous surface, sloping downwards towards the flap 103 body. The shape of the flap 103 can be seen in Figures 21a and 21b.

The sheet spring 106 acts against this wedge cam 122 to bias the flap 103 to the open position. The highest point of the wedge is between points 128 and 132 when the flap 103 is in the closed or abuse position, activating the sheet spring 106, and the highest point of the wedge is 134 when the flap 103 is in the open position, relaxing the sheet spring 106.

In an example embodiment, the sheet spring may require 1.7N of force (or 0.02295Nm of rotational torque) to hold it in the “handle closed” position. It requires 3.5N of force (or 0.04725Nm of rotational torque) to hold it in the abuse position and it requires zero force to hold it in the “handle open” position.

In the same example embodiment, for the wedge cam, when the handle is closed, the flap is at zero degrees, or vertical, and thus the point of the wedge cam which is highest is point 128. When the handle is open the flap is at a minimum of 90 degrees, or approximately horizontal, and thus the point of the wedge cam which is highest is point 134. When the handle is venting the flap is at a minimum of 90 degrees, or approximately horizontal, and thus the point of the wedge cam which is highest is point 134. When the flap has been forced into the abuse position, typically 340 degrees, the point of the wedge cam which is highest is between points 128 and 132. These positions are shown in Figures 17a – 17c.

The cross sectional views of Figures 17d – 17f show these positions of the wedge cam within the assembled window fastener. The shape of the flap 103 also allows for rotation of the flap 103 backwards from the closed position, away from the open position. As before, when the fastener is closed, the extension 4b pushes the flap 103 downwards against the force of the sheet spring 106.

The outer surface of the receiving member or cam element 107 is concentric with hollows 124 and lobes 137. These hollows 124 and lobes 137 may also be on an inner surface. The cartridge 126 also has a series of lobes 123 on its inner surface which resist the rotational movement of the lobes 137 on the cam element 107, immediately after they align into interference contact with the lobes 123 on the cartridge 126. These lobes 123 may also be spaced around an outer surface. The lobes 123 have cut- out or hollow sections 135 behind them which deform to allow for the movement of the cam element 107 past them when sufficient force is applied to deform them.

As with the torsion spring fastener, in use isolated from the sheet spring, the operator rotates the handle away from one of the neutral closed, open, or venting positions. When the handle is moved beyond an eighth of a turn, or beyond the maximum feel of the contact force between the cam and hollow, the handle will spring forward another eighth of a turn into the next neutral position. If the handle is rotated less than an eighth of a turn, then the handle will spring back to the neutral position it came from. If the handle is rotated exactly an eighth of a turn, its momentum should carry it to the next neutral position. Preferably the handle will not rest between the neutral positions. Preferably the shapes of the cam and hollows in this embodiment are symmetrical, which means that the forces are the same in a clockwise or anti-clockwise direction.

As the fastener wears, the forces required to begin opening or closing it changes. A typical range of forces may be 11N to open the fastener when it is new, to 2.5N when it is considered to be at the end of its useful life.

In an example embodiment, the sheet spring may require 1.7N of force (or 0.02295Nm of rotational torque) to hold it in the “handle closed” position. It requires 3.5N of force (or 0.04725Nm of rotational torque) to hold it in the abuse position and it requires zero force to hold it in the “handle open” position.

In the same example embodiment, for the wedge cam, when the handle is closed, the flap is at zero degrees, or vertical, and thus the point of the wedge cam which is highest is point 128. When the handle is open the flap is at a minimum of 90 degrees, or approximately horizontal, and thus the point of the wedge cam which is highest is point 134. When the handle is venting the flap is at a minimum of 90 degrees, or approximately horizontal, and thus the point of the wedge cam which is highest is point 134. When the flap has been forced into the abuse position, typically 340 degrees, the point of the wedge cam which is highest is between points 128 and 132.

The lobe 123 and hollow 124 positions can be seen with their corresponding handle positions in Figures 20a – 20j.

The deformation is shown in more detail in Figures 22a and 22b.

Approximately 1.3mm of interference depth is provided intermediate of the predetermined positions when the handle is in one of the neutral positions.

The bridge member that deforms is approximately 1.65mm thick.

To assemble the sheet spring fastener, the small washer 121 is placed on the shaft of the handle 104, followed by the base 102. The cam element 107 is then fixed to the handle shaft 105 by a screw 13 or similar, the handle 104 having an aperture to receive the screw 13 (not shown). The cartridge 126, holding the sheet spring 106 is pressed into place in the base 102. As the sheet spring 106 is only tensioned once it is in use, this is simpler than inserting a typical tensioned spring. The flap 103 may be inserted when the handle 104 is in the open position and the cover 5 slid over the base 102 to secure it. This assembly process is simple and does not require particular specialist equipment. It allows for the fastener to be assembled or disassembled on site and the parts to be easily replaced if damaged. Additionally, each fastener may have several modular handles, including left handed, right handed, venting and non-venting handles. The simple assembly process allows for the fastener to be assembled with the desired handle when required.

The sheet spring may be made from plastic, steel or stainless steel. Steel is preferable over plastic, as it likely has a more resilient spring characteristic over its life. Stainless steel is additionally more resistant to rust. When tested in isolation from the fastener 101, the sheet spring was found to deflect 2.5mm under 25N of load. The sheet spring is able to withstand a larger number of operational cycles than the torsion spring embodiment.

To further simplify manufacturing and reduce the component count, the cartridge, sheet spring and base may form a single moulded component 240. An exploded view of a window fastener having this configuration is shown in Figure 25a and an assembled view in Figure 25b. Most of the components are the same as the previous embodiment of the window fastener, however with the base 202, sheet spring 206 and cartridge 226 integrated into one part rather than requiring assembly of the three separate parts. A close up view of the base is shown in Figure 26a and an exploded view in Figure 26b. The form of the cartridge 226 has been adapted to suit this configuration as the sheet spring holder 239 now forms part of the base. The cartridge 226 is split into two pieces and has lobes 223. When the parts are assembled, the cartridge 226 slightly overhangs the sheet spring 206 when both are inserted into the base 202 to hold it in place. Front, side and back views of this part 240 are shown in Figures 27a, 27b and 27c respectively.

The preferred materials for this embodiment and the previous embodiment are the same, with the sheet spring 206 made from plastic, steel or stainless steel. The base 202 and cartridge 226 are made from injection moulded plastic, overmoulded onto the sheet spring. The base and cartridge could be moulded as one plastic moulding around the spring.

However, zinc is not expected to be suitable for a single moulding in this version. The base and cartridge could however be moulded in a combination of a diecast zinc base with an over moulded plastic cartridge around the spring.

This single moulded component removes the assembly steps of inserting the sheet spring 206 and cartridge 226 into the base 202. Otherwise the assembly process is much the same, as is the function of the window fastener.

In use, the window fastener 101 is connected to the moveable sash of a window on the opposite side to the window frame hinge or axis of rotation between the sash and frame. For example, if the sash pivots open from the top edge, the window fastener 101 will be located on the bottom or lower side of the sash. To lock the window, a user pulls the lower edge of the sash inwards to pivot it inwards and closed, and then rotates the handle 104 from the open position to the closed position. This causes extension 4b to rotate across the inner surface of the flap 103, across one of the angled side surfaces and then onto the flat surface on the inner side of the thicker central section. As the extension 4b passes across the inner surface of the flap 103, it pushes the flap 103 downwards. When the flap 103 is downwards in the closed position, the flap 103 prevents the sash from rotating back outwards. The flap 103 rotates downwards against the sheet spring 106.

To open the window, a user rotates the handle 104 to the open position.

The sheet spring 106 pushes the flap 103 back upwards, and the sash can be rotated or pushed outwards. In previously known fasteners of a similar type, if a user has the window open, but the handle (and flap) is not quite fully in the open position, then if a user attempts to pull the sash closed, the flap will be angled downwards slightly and damage can occur as this is pulled into contact with the outside of the frame. The window fastener 101 of the present invention helps to prevent this in two ways: firstly the flap 103 can rotate backwards past the closed position (vertically downwards in the embodiment described), absorbing the shock of the impact so that there is less likelihood of damage; and secondly by having a handle connection where the handle 104 positively locates between positions as it is rotated, so there is less likelihood that the handle 104 will inadvertently be left in a position between fully open or fully closed.

The sheet spring design has a number of advantages over the torsion spring design. The sheet spring itself is cheaper and faster to produce than the torsion spring and can withstand a greater number of operational cycles. The window fastener is less fiddly to manufacture and assemble than the torsion spring design.

While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant’s general inventive concept.

Claims (18)

CLAIMS :

1. A window fastener comprising: a base, configured for connection to the moveable sash of a window; a flap pivotally connected to the base; and 5 a handle; wherein the base and flap are configured and connected so that the flap can rotate between a closed position and an open position; the base and flap further configured and connected so that the flap can pivot a substantial angle past the closed position, away from the open position. 10

2. A window fastener as claimed in claim 1 wherein the base further comprises a handle connection mechanism configured to allow the handle to be connected to the base so that in use a user can manipulate the handle and cause the flap to move from the open to the closed position, the handle connection mechanism further configured to bias the handle to 15 positively locate into at least the open position.

3. A window fastener as claimed in claim 2 wherein the handle connection mechanism comprises a receiving member configured to receive part of the handle to enable connection of the handle to the base and rotation of the receiving member about an axis, the base and the 20 exterior of the receiving member shaped to interact as the receiving member rotates to positively locate the handle.

4. A window fastener as claimed in claim 3 wherein the base and the exterior of the receiving member are shaped to positively locate the handle into at least the open position and the closed position.

5. A window fastener as claimed in claim 4 wherein the handle has a separable button made from injection moulded plastic, rubber or resin located in a pocket in one of the extensions of the handle.

6. A window fastener as claimed in claim 5 wherein the pocket in the 5 extension of the handle has a depth of at least 2mm.

7. A window fastener as claimed in claim 3 or claim 4 wherein the receiving member comprises a body having a central aperture for connection to the handle, an outer or an inner surface shaped to comprise a plurality of rounded lobes, each extending along the body substantially 10 axially and spaced around the perimeter of the body.

8. A window fastener as claimed in claim 3 or claim 4 wherein the receiving member comprises a body having a central aperture for connection to the handle, an outer or inner surface shaped to comprise a plurality of hollows, each extending along the body substantially axially 15 and spaced around the perimeter of the body.

9. A window fastener as claimed in any one of claims 1 to 8 further comprising a spring means configured to bias the flap towards the open position.

10. A window fastener as claimed in claim 9 wherein the spring means is a 20 torsion spring.

11. A window fastener as claimed in claim 10 wherein the torsion spring comprises a pair of helically wound wire-formed central body elements, one end of the wire extending from each of the central body elements to form an unbroken loop that connects between the central body elements 25 to hold the central body elements in a spaced-apart arrangement with a substantially common central axis.

12. A torsion spring for a window fastener as claimed in claim 11 wherein the extending ends of the wire are located on the outer ends of the central body elements.

13. A torsion spring for a window fastener as claimed in claim 11 or claim 5 12 wherein the sides of the unbroken loop extend beyond the outer ends of the central body elements.

14. A window fastener as claimed in claim 9 wherein the spring means is a sheet spring.

15. A window fastener as claimed in any one of claims 1 to 14 wherein the 10 flap comprises a pair of substantially cylindrical extensions, extending from the body of the flap and aligned to form an axis of rotation for the flap, the base comprising a pair of corresponding cut-outs into which the cylindrical extensions locate in use, the window fastener further comprising a cover configured to slide over the base to hold the flap and base together when 15 the cylindrical extensions are located in the cut-outs.

16. A window fastener as claimed in claim 1, comprising: a base, configured for connection to the moveable sash of a window; the base further comprising a handle connection mechanism configured to allow the handle to be connected to the base so that in use a 20 user can manipulate the handle and cause the window fastener to move from an open to a closed position, the handle connection mechanism further configured to bias the handle over a substantial angle towards and to positively locate the handle into at least the open position.

17. A window fastener comprising: 25 a base, configured for connection to the moveable sash of a window; a flap pivotally connected to the base; and a handle; wherein the base and flap are configured and connected so that the flap can rotate between a closed position and an open position; the base 5 and flap further configured and connected so that the flap can pivot past the closed position, away from the open position, to a further position in which the flap contacts a surface of the window sash.

18. A window fastener as claimed in claim 17, wherein the handle is configured to move the flap from the open position to the closed position 10 and wherein the flap is free to move independently of the handle to the further position.