SEALING STRIPS

Abstract: A sealing strip, such as for fitting to the frame of a door opening in a motor vehicle body, comprises a longitudinally extending channel-shaped mounting portion (8) incorporating a channel-shaped reinforcing carrier (20). A hollow tubular longitudinally extending sealing portion (10) is attached to the outside of the mounting portion (8). When such a strip is bent to follow curves in the door frame, the increased tension in the mounting portion (8) at the curves may cause the sealing portion (10) to move inwardly of the curve into the position shown in the dotted line. In order to avoid this, the sealing strip, and particularly the mounting portion (8), is longitudinally compressed at positions corresponding to the positions where curves are to be formed in the strip. This local longitudinal compression helps to maintain the sealing portion (10) in its correct attitude.

Description: SEALING STRIPS The invention relates to a longitudinally extending sealing strip for providing a seal between the surround of an opening and a closure member for the opening, the sealing strip comprising a longitudinally extending mounting portion incorporating resilient reinforcement means, and a longitudinally extending sealing portion on the mounting portion, the mounting portion and the resilient remforcemert means being locally stressed lengthwise at a position or positions corresponding to bends or curves m the surround. The invention also relates to a method of making a longitudinally extending sealing strip for providing a seal between the surround cf an opening and a closure member for the opening, the sealing strip comprising a longitudinally extending mounting portion incorporating resilient reinforcement means, and a longitudinally extending sealing portion on the mounting portion, the method including the step of locally stressing the mounting portion and the resilient reinforcement means lengthwise at a position or positions corresponding to bends or curves in the surround . Such a sealing strip and such a method aie known from US-A-5 249 353. In this known strip and method, the strip is locally stretched lengthwise at the said position or positions. Therefore, when the strip is bent to follow a bend or curve, the resultant lengthwise compression of the sealing portion tends to return the stress therein towards the original value (before the initial tension) , with the aim of avoiding "buckling" of the sealing portion. However, the success of this process depends on the extent to which the initial tension matches the subsequent compression . According to the invention, the sealing strip as first set forth above is characterised m that the mounting portion and the resilient reinforcement means are locally stressed lengthwise by being locally compressed lengthwise at the said position or positions . According to the invention, also, the method as first set forth above is characterised m that the lengthwise locally stressing step comprises the step of locally compressing the mounting portion and the resilient reinforcement means lengthwise at the said position or positions. The local compression of the mounting portion and the resilient reinforcement means has the effect of shifting the neutral bending axis of the strip towards the inside of the bends or curves, reducing the tendency of the sealing portion to buckle and helping to ensure that the sealing portion maintains the correct positional relationship with the mounting portion. Sealing strips embodying the invention, and methods according to the invention of making sealing strips, will now be described, by way of example only, with reference to the accompanying diagrammatic drawings m which: Figure 1 is a perspective view of a motor vehicle body with one of its doors removed to show where one of the sealing strips may be fitted; Figure 2 is a cross- section through one of the sealing strips, showing it mounted m position; Figure 3 is a perspective view of a reinforcing carrier which can be used m the strip of Figure 2; and Figure 4 is a side view showing one of the strips arranged in continuous loop form for mounting around the frame of the drawer opening . As shown m Figure 1, a motor vehicle 5 has the driver's door removed to show a sealing strip 6 mounted on the frame running around the door opening . The sealing strip 6 is shown m more detail m Figure 2. It comprises two parts: a gripping or mounting portion 8 and a sealing portion 10. The gripping portion 8 is of channel-shape m cross-section and embracingly grips a mounting flange 12 which forms the frame of the door opening. The flange 12 is formed where inner and outer body panels 14,16 come together at the door opening and are spo -welded (for example) together to form the flange The gripping portion 8 comprises extruded plastics or rubber material 18 m which is embedded a reinforcing core or carrier 20 of resilient material such as metal. One form which the carrier 20 can take is shown in Figure 3 As there shown, it may be formed of (inverted) U-shaped elements 21 connected together by integral connecting links 22. Instead the elements 21 may be entirely disconnected. In another example, the carrier may be made of wire looped to and fro. Other forms of carrier are possible. The carrier need not be made of metal. The carrier may be incorporated into the extruded material 18 by means of a cross-head extruder The extruded material 18 has integral gripping lips 23,24 on opposite inside faces of the channel. As shown in Figure 2, the lips made contact with the opposite outer faces of the flange 12. They, together with the resilience given to the mounting gripping portion 8 by the resilient carrier 20, ensure that the gripping portion 8 firmly embraces the flange. Advantageously, the lips 23,24 are extruded from material which is softer than the remainder of the material 18, so as to increase their frictional grip on the flange. In addition, and as shown in Figure 2, one of the body panels 14 forming the flange 12 may be given an outwardly directed bend 26 which helps to secure the gripping portion 8 in position. The gripping portion 8 is m this example extended :c form a so- called "cosmetic" lip 28 which in use embraces the edge of a body trim panel 30 so as to hide the edge and help to secure the panel m position. The sealing portion 10 is of longitudinal tubular form and is secured to the outside of one channel side wall of the mounting portion 8. The sealing portion 10 may be made of extruded soft rubber or plastics material or from a thermoplastic elastomer. Advantageously, it is of foamed or cellular construction to increase its softness. In the form shown in Figure 2, it is extruded to be of bi- tubular form. However, other forms are possible. The sealing portion 10 may be extruded separately and then secured to the outside channel side wall by means of an adhesive. Instead, though, it may be integrally extruded with the material 18. The outside of the gripping portion 8 may be covered in fabric 32 for decorative purposes. In use, the mounting portion 8 mounts the sealing strip around the door surround so that the sealing portion 10 faces outwardly of the door opening and becomes partly compressed by the closing door. In this way, it produces a weather- tight seal. Advantageously, the strip 6 is, after manufacture, formed into a continuous loop as shown in Figure 4, matching the shape and size of the door opening and arranged with pre- formed curves A,B,C,D and E to match the curves in the door opening; the strip is, however, sufficiently flexible to enable it to be mounted in position on the door surround. In accordance with a feature of the invention, the sealing strip is compressed lengthwise over short portions of its length which correspond to the positions where the curves A,B,C,D and E (Figure 4) are to be formed, this lengthwise compression being carried out while the strip is still m straight form. As shown in Figure 4, for curve A, the strip is compressed lengthwise over the region F (before bending) . This compression may be carried out by passing the strip through a set of spaced pairs of rollers which can be controlled to run at different rotational speeds. As the strip passes longitudinally through the pairs of rollers, the pairs of rollers are normally controlled to run at the same speed so as to have no effect on the strip but are programmed to run at different speeds temporarily as the strip passes through them, so as to apply longitudinal compression to the relevant parts of the length of the strip. The effect of this local compression is to ensure that the sealing portion 10 (Figure 2) maintains its correct attitude at the curves. Figure 2 shows, m dotted form, the attitude which the sealing portion 10 tends to take, with respect to the gripping portion 8, at the curves m the continuous loop of Figure 4 if the sealing strip is not longitudinally compressed at such a curve. In this case, tension m tne channel side walls of the mounting portion 8 causes the sealing portion 10 to tend to assume the dotted position shown m Figure 2 when the strip is bent to follow the desired curve. However, if compression is locally applied lengthwise to the sealing strip, and particularly to its carrier, m the region of the curves, it is found that the attitude of the sealing portion 10 does not significantly change at the curves and thus maintains the full-line position shown m Figure 2. More specifically, the local compression of the strip compresses the carrier 20 lengthwise, partially closing the gaps between the elements 21 (see Figure 3), particularly along the inverted base of the channel. This has the effect of shifting the neutral bending axis of the strip more closely to the plane of the inverted channel base. In other words, when the strip is bent to follow the curves A,B,C,D and E (Figure 4), with the open mouth of the channel of the mounting portion on the outside of each curve, the neutral bending axis (the line along which the material of the strip is neither compressed nor tensioned at the curves) lies more closely to the inside of the curves, thus holding the sealing portion 10 in the correct attitude and reducing any tendency for it to buckle or wrinkle at the curves. Where sharp curves are required m sealing strips, tending to cause significant distortion of the sealing portion, it is known to cut a section out of the sealing portion and to produce a moulded insert matched to the sharp corner. However, it is found that local compression of the sealing strip m the manner described above can obviate the need for such a moulded insert, enabling a sharp curve to be produced simply by bending the sealing strip. It is not necessary for the strip to be formed into a closed loop (as shown m Figure 4) . It may be formed into an open loop or left m the straight form. In the latter case, though, it is necessary to be able to locate the positions along the strip where the local compression has taken place.

Claims: CLAIMS 1. A longitudinally extending sealing strip (6) for providing a seal between the surround (12) of an opening and a closure member for the opening, the sealing strip comprising a longitudinally extending mounting portion (8) incorporating resilient reinforcement means (20), and a longitudinally extending sealing portion (10) on the mounting portion (8), the mounting portion (8) and the resilient reinforcement means (20) being locally stressed lengthwise at a position or positions (A,B,C,D,E) corresponding to bends or curves m the surround (12), characterised in that the mounting portion (8) and the resilient reinforcement means (20) are locally stressed lengthwise by being locally compressed lengthwise at the said position or positions (A,B,C,D,E) . 2. A strip according to claim 1 characterised m that the local lengthwise compression shifts the neutral axis of the bending towards a position corresponding to the inside of the bends or curves . 3. A strip according to claim 1 or 2 , characterised in that the mounting portion (8) is channel -shaped for gripping a flange (12) or the like forming the surround of the opening. 4. A strip according to claim 3, characterised m that the reinforcement is a channel -shaped metal carrier (20) . 5. A strip according to claim 4, characterised m that the resilient reinforcement means (20) is provided with slots at least in the base of its cnannel which become at least partially closed by the lengthwise compression. 6. A strip according to any preceding claim, characterised in that the sealing portion is of hollow tubular form (10) . 7. A strip according to any one of claims 3 to 5, characterised in that the sealing portion is of hollow tubular form (10) and mounted on one outside side wall of the channel of the mounting portion (8) . 8. A strip according to any preceding claim, characterised in that the mounting portion (8) comprises extruded plastics or rubber material. 9. A strip according to any preceding claim, characterised in that the sealing portion (10) comprises extruded rubber or plastics material . 10. A strip according to any preceding claim, characterised in that it is formed into a closed loop matching the shape and size of the opening and having a plurality of bends or corners (A,B,C,D,E) at each of which the mounting portion is locally compressed lengthwise. 11. A method of making a longitudinally extending sealing strip (6) for providing a seal between the surround (12) of an opening and a closure member for the opening, the sealing strip (6) comprising a longitudinally extending mounting portion (8) incorporating resilient reinforcement means (20), and a longitudinally extending sealing portion (10) on the mounting portion (8), the method including the step of locally stressing the mounting portion (8) and the resilient reinforcement means (20) lengthwise at a position or positions (A,B,C,D,E) corresponding to bends or curves m the surround (12) , characterised m that the lengthwise locally stressing step comprises the step of locally compressing the mounting portion (8) and the resilient reinforcement means (20) lengthwise at the said position or positions (A,B,C,D,E) . 12. A method according to claim 11, characterised in that the local lengthwise compression shifts the neutral axis of bending towards a position corresponding to the inside of the bends or curves . 13. A method according to claim 12, characterised in that the resilient reinforcement means (20) is channel -shaped metal with slots in the base of the channel which become at least partially closed by the local compression. 14. A method according to any one of claims 11 to 13, characterised by the step of forming the sealing strip (6) into a loop matching the size and shape of the surround. 15. A method according to claim 14, characterised in that the loop is a closed loop. 16. A method according to any one of claims 11 to 15, characterised m that the lengthwise compression step is carried out when the strip is substantially straight.

Inventors: GREVEN HELMUT, GREVEN, HELMUT
Applicants: DRAFTEX IND LTD, GREVEN HELMUT, DRAFTEX INDUSTRIES LIMITED, GREVEN, HELMUT
Application year: 1998
Main classification: B60J10
IPC codes: B60J10, B60R13, F16J15