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(11) | EP 0 262 877 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Pile weatherstripping |
| (57) A fin pile weatherstrip is provided in which the fin (12) has a lower coefficient
of friction surface. It has been found that with such a reduced coefficient of friction
fin (12), the breakaway force required to open a sliding door or window (15) incorporating
such a fin pile weatherstrip can be markedly reduced, so making the door easier to
open. Air infiltration performance is not affected. |
[0002] Finned pile weatherstrip is constructed from a woven backing with an upstanding pile, often of polypropylene yarn. A fin, usually of polypropylene film material, extends vertically from the backing along the length of the weatherstrip between the pile. In one form, the upper free edge of the fin extends above the pile.
[0003] One use of such a pile weatherstrip is the mounting of the weatherstrip in sliding doors or windows in order to form a seal between movable door or window panel and fixed frame to reduce the passage of air and water therebetween. The fixed frame may, for example, be rectangular with vertical jambs and horizontal head and sill members. The movable panel may be in the form of a rectangular frame which slides in a plane parallel to the plane of the fixed frame to open and close the door or window. the finned pile weatherstrip is generally mounted to extend along the jambs and across the head and sill of the stationary frame - although it may be mounted on the movable panel.
[0004] When the movable panel of the door or window is closed, surfaces of the movable panel engage with the fin pile weatherstrip. When the movable panel is opened, an initial force must be applied to the movable panel in order to overcome the inertia of the movable panel and to break the engagement with the finned pile weatherstrip. This force is termed the "breakaway force". Once these initial forces have been overcome, there is a steady force which must be appllied to the movable panel in order to maintain the movement. This is termed the "sliding force". In general, the breakaway force and sliding force are inter-related to the extent that a reduction in breakaway force (which is generally the larger of the two forces) will produce a reduction in sliding force (which is generally the lesser of the two forces).
[0005] The magnitude of the breakaway force and the sliding force are important because, if they are too great, the door or window cannot be opened by, for example, children or elderly or infirm persons and as a result of this manufacturers consider this an important feature of such doors and windows. Accordingly, in order to make the opening of a door or window as easy as possible, it is desirable to have the breakaway force and the sliding force as low as possible, without reducing the performance of the seal to an unacceptable level.
[0006] In order to reduce the breakaway froce and the sliding force by reducing the resistance generated by engagement between the movable panel and the finned pile weatherstrip, it has been proposed in EP-A-0020136 to increase the height of the fin above the pile so that it is a substantial distance above the pile. It has been found, however, that this produces no consistent benefit - in some cases raising the fin a substantial distance above the pile will increase the breakaway force and the sliding force.
[0007] Thus, the technical problem sought to be overcome by the invention is the production of finned pile weatherstrip which allows the breakaway force and the sliding force to be consistently reduced.
[0008] According to the invention, there is provided a weatherstrip comprising an elongate backing having a pile and a fin upstanding therefrom, the fin extending along the backing within the pile and extending above the pile, for sealing contact with a door or window frame, at least said contacting portion of said fin being treated to provide a surface of reduced coefficient of friction with the said door or window surface, or being of a material having a lower coefficient of friction with said door or window surface than polypropylene.
[0009] By having the fin of decreased coefficient of friction, it has been found that the breakaway force is reduced.
[0010] The following is a more detailed description of one embodiment of the invention, by way of example, reference being made to the accompanying drawings in which:-
Figure 1 is a cross-sectional view of finned pile weatherstrip, and
Figure 2 is a cross-section of the finned pile weatherstrip of Figure 1 mounted between fixed and movable members of a door or window, and
Figure 3 is a graph of breakaway force against fin height for a prior art fin of a material having a higher coefficient of friction with anodized aluminium and a fin of the pile weatherstrip of Figures 1 and 2 and having a lower coefficient of friction with anodized aluminium.
[0011] Referring first to Figure 1, the pile weatherstrip comprises a backing strip 10 formed of a woven material. A pile 11 extends vertically upwardly from the backing strip and is formed by known weaving techniques. The material of the pile may be a polypropylene yarn. The height H of the pile is cut to a predetermined value.
[0012] A pair of fins 12 extend along the backing strip 10 within the pile 11. The fins are formed from a sheet of material bent into a U-shape and welded at the base 13 of the U to the backing strip 10. The fixing need not be by welding. It could be by gluing. The fins 12 need not be fixed to the backing strip 10 - they could be fixed to the pile 11. There could be only one fin.
[0013] The material of the sheet is either of polypropylene treated, for example, with a silicon compound, or is of a material having a lower coefficient of friction than polypropylene. Alternatively, it could be formed from polypropylene to which has been added a suitable amount of a compound which has the effect of reducing the coefficient of friction of the polypropylene. For example, a suitable wax-based compound may be added to the polypropylene of the fin.
[0014] The free edges of the fins 12 extend above the pile by a desired height (h). This height (h) may be between 0.015 inches and 0.200 inches or more.
[0015] In use, as shown in Figure 2, the finned pile weatherstrip is mounted in a carrier 14 in a door or window and, when the door or window is closed, it engages with a second door member 15 to close the gap between them. The height H of the pile 11 may be arranged so that it just equals the gap D between the members 14, 15 or, preferably, so that H is just greater than D - so placing the pile 11 under slight compression (for example 5% compression). This latter mode has the benefit of inhibiting the flow of air through the gap D should the fin 12 be broken.
Example 1
[0016] In order to test a pile weatherstrip mounted as described above, a finned pile weatherstrip having a fin with a coefficient of friction with anodized aluminium of 0.172 was mounted in a window and the breakaway force was tested in accordance with BS 6375, BS 5286 and BS 5368. A known finned pile weatherstrip having a coefficient of friction with anodized aluminium of 0.258 was tested in the same way.
[0018] It will be seen that for all fin heights above the pile, the breakaway force of lower coefficient of friction fin was less than the breakaway force of higher coefficient of friction fin. For certain fin heights, the breakaway force was as much as 50% less and the average benefit was about a 40% reduction.
Example 2
[0019] Two types of pile weatherstrips were prepared. The first type (Pile 1) was a commercially available weatherstrip having a width of 6.7mm. The height (H) of the fin above the pile was 1mm and the fin was of untreated polypropylene. Three sizes of this type were prepared, one having a pile height (H) of 4.5mm, a second having a pile height (H) of 5.0mm and a third having a pile height of 7.0mm.
[0020] The second type of pile weatherstrip (Pile 2) was constructed as the first pile weatherstrip, but the polypropylene of the fin contained an additive for reducing the coefficients of friction of the fin. Again, three sizes of this type were prepared with pile heights (H) of 4.5mm, 5.0mm and 7.0mm.
[0021] Pile 1 and Pile 2 were fitted successively to a horizontal sliding window having a sliding sash of width 0.94m and height 0.905m, and to a paito door having a sliding panel of width 1.165m and height 1.92m. In the window, a pile height of 4.5mm was used throughout, but in the door, a pile height of 5.0mm was used at the jambs and a pile height of 7.0mm at the head and sill. The piles were mounted under 5% compression.
[0022] The breakaway force and the sliding force were measured in accordance with the BS6375, BS5286 and BS5368, with the following results.
[0023] It will be seen, therefore, that the provision of a fin having a co-efficient of friction with the co-operating surfaces that is lower than that of conventional fins, has the benefit of achieving substantial reductions in the breakaway force and sliding force when used in doors and windows. This allows the movable door and window leaves to be more readily opened and thus reduces the likelihood that children or elderly or infirm persons will find windows and doors fitted with such pile, difficult or impossible to open and close.
1. A weatherstrip of the kind comprising an elongate backing (10) having a pile (11)
and a fin (12) upstanding therefrom, the fin (12) extending along the backing (10)
within the pile (11) and extending above the pile, for sealing contact with a door
or window frame (15) characterised in that, at least said contacting portion of said
fin (12) is treated to provide a surface of reduced co-efficient of friction with
said door or window surface (15), or being of a material having a lower coefficient
of friction with said door or window surface than polypropylene.
2. A weatherstrip according to claim 1 characterised in that the surface of the fin
(12) is treated with a silicon compound.
3. A weatherstrip according to claim 1 characterised in that the fin (12) is formed
from a mixture of a polypropylene and a wax-based compound.
4. A weatherstrip according to any one of claims 1 to 4 characterised in that the
fin (12) extends above the pile by between 0.4mm and 5mm.
5. A weatherstrip according to any of claims 1 to 4 characterised in that two side-by-side
fins (12) are provided, both fins extending the same distance above the pile.