FR2975348A1 - Seal for e.g. side opening frame of window in car, has core made of plastic material and sealing lips made of another plastic material that is different from former material and flexible than former material - Google Patents

Abstract

The seal (1) has a core (3) comprising a rigid elongated form along longitudinal direction, and lower and upper sealing lips (5, 7) that are rigidly fixed at the core. The core is made of a plastic material i.e. polypropylene, and the sealing lips are made of another plastic material e.g. rubber, that is different from the former material and flexible than the former material. The core comprises a U-shaped section in a transverse plane. The core includes openings spaced from/to each other along the longitudinal direction. The openings are used for positioning the seal on a support. An independent claim is also included for a method for manufacturing a seal.

Description

The invention relates generally to seals for a motor vehicle, in particular seals intended to seal with the windows of the side openings.

More specifically, the invention relates in a first aspect a seal for a motor vehicle, of the type comprising a core having a longitudinally elongate shape, and at least one sealing element rigidly fixed to the core. Some joints must have a longitudinal curvature, for example to match the shape of the opening to be closed by ice. This may be the case for the two front lateral opening of the vehicle, in which the openings are delimited to the front by uprights having for example a vertical portion and a portion inclined relative to the vertical. Seals are known which, in order to make it possible to obtain such a longitudinal curvature, comprise a metal core, the sealing element being a lip made by overmolding a material such as EPDM around the metal core. . The metal core is then mechanically deformed so as to give the joint the desired longitudinal profile. Such a seal is expensive to manufacture, and the price of the piece itself is high. The seal is fixed by riveting on its support, which requires the production of orifices in the metal core. The orifices are expensive to make. Moreover, the riveting operation must be performed in the factory where the gasket is assembled to its support, this operation being relatively complex and time consuming. In this context, the invention aims to provide a seal that can adopt a longitudinal curvature and is less expensive.

To this end, the invention relates to a seal of the aforementioned type, characterized in that the core is made of a first plastic material, and the sealing element made of a second plastic material different from the first plastic material and more flexible than the first plastic material. Because the metal core is replaced by a core of a first plastic material, the seal is less expensive. Furthermore, the seal is generally attached to a support member, itself having a zone of a plastic material on which the seal is attached. Because the two parts are in plastic materials, it is possible in most cases to weld the gasket on its support, which is a faster and less expensive operation than to assemble the gasket by riveting on its support.

The seal is rectilinear or has a longitudinal curvature. In this case, the core has a longitudinal curvature. The term "longitudinal curvature" here means that, when the web is followed from one longitudinal end to the opposite longitudinal end, the movement is not rectilinear but instead comprises at least one change of direction. The movement can have several changes of direction, each change of direction can influence the movement in any direction. The core thus typically has one or more rectilinear longitudinal sections, and one or more longitudinal sections having a longitudinal curvature. As a variant, the core only has sections having a curvature, and no rectilinear longitudinal sections. In this case, the longitudinal sections have different curvatures, or all have the same curvature. The arch is constant or variable along each section. The curvatures are typically all turned on the same side, which means that the concavity of the different sections having a curvature is turned on the same side of the joint. Alternatively, some sections have concavities turned on one side, and others have concavities turned on a second side opposite the first. As the core has a longitudinal curvature, the first plastic material is chosen to be adapted to allow thermoforming of the core. This thermoforming operation aims to give the soul the desired curvature, from a situation where said soul is rectilinear. The first plastic material is then chosen so as to allow this deformation, and to give the core, after cooling, sufficient rigidity for the soul to retain the desired longitudinal curvature, despite the shrinkage that may occur at the time of cooling of the first plastic material. The second plastic material is softer than the first plastic material. It is intended to achieve sealing, for example with the ice of the opening. It must be flexible enough to adapt to the longitudinal curvature of the soul, and in particular not to prevent the thermoforming of this soul.

The sealing element completely or partially covers the core and has a shape typically lip-shaped. As a variant, this element is a bead or any other type of element adapted to create a tight contact with another part, for example with an ice-cream of the vehicle. The gasket typically comprises at least one sealing element, and most often comprises two sealing elements. Each element extends longitudinally substantially over the entire length of the core. The two elements are parallel to each other. Preferably, the core has a U-section in a transverse plane. Here is meant by transverse plane a plane taken perpendicularly to the longitudinal center line of the soul. The central line is rectilinear when the soul is rectilinear, and has curvatures when the soul has a longitudinal curvature. This U-section gives the soul greater rigidity than if the soul had an L-section. This is particularly important because the core is made of a plastic material and not a metal.

The U-section also allows to pre-position the seal on its support, before final fixing. The section of the core is substantially constant over most of the longitudinal length of said core, and is preferably constant over substantially the entire length of the core.

The first plastic material advantageously comprises a polypropylene. Preferably, the first plastic material is polypropylene. Polypropylene refers here to propylene polymers alone called homopolymer (PP) or propylene copolymers (PIE) and another material. Also included in this category are blends of polypropylene and another material. These other materials may in particular be fibers, for example glass fibers or mineral fillers, for example talc. It is noted that those skilled in the art can, depending on these needs, use this or that type of polypropylene with fiber blends or more or less important fillers. Polypropylene is particularly advantageous because it is well suited to perform the thermoforming of the core, but also for its rigidity, especially in its mixed version, which makes it possible to avoid the metal core as known in the prior art. moreover, the support piece to which the gasket is to be attached is frequently made of polypropylene. The attachment by welding of the gasket on its support is particularly easy to achieve when the two elements to be welded on one another are in the same material, and more particularly polypropylene. In addition, polypropylene is easily extrudable. It is thus possible to make the joint by coextrusion of the first and second plastic materials, this coextrusion step being followed by the thermoforming step where appropriate. Alternatively, the seal is made according to a different method. The soul is first manufactured by any suitable method such as injection or extrusion. It is then, if necessary, shaped by thermoforming. Finally, the sealing element or elements are attached to the core, for example by heat sealing. The second plastic material is typically a natural elastomer, for example rubber, or synthetic of the TPE-ThermoPlastic Elastomer type, for example an EPDM. According to a second aspect, the invention relates to a motor vehicle structure comprising a seal having the above characteristics, and a support on which the seal is welded. The gasket is typically ultrasonically welded to the substrate. However, other welding methods can be envisaged, in particular by vibration, by hot pebble or point-energy welding. Those skilled in the art will choose according to these constraints the most suitable method among the various existing welding processes. The structure is typically a side opening. In a variant, the structure is a hood, a tailgate, a trunk, a roof opening, etc. According to a third aspect, the invention relates to a method for manufacturing a seal having the above characteristics, the method comprising a thermoforming step provided to impart a longitudinal curvature to the core. Before the thermoforming step, the core is rectilinear. Thermoforming consists in plastically deforming, hot, the core of the joint, the latter after cooling retaining the desired shape, with a slight shrinkage possibly during cooling. Preferably, the thermoforming step is performed by biasing the seal against an imprint of suitable shape, using a roller. The cavity typically has a seal receiving surface having a profile longitudinally corresponding to the desired longitudinal curvature. The roller mechanically biases the seal against the surface. It moves longitudinally along the joint, so as to successively press all areas of the joint that must be formed against the surface of the footprint. During the thermoforming operation, the core is heated, for example by means of infrared lamps or by any other suitable heating means. Preferably, the method comprises, before the thermoforming step, a coextrusion step of the core and the sealing element. Such a production method is particularly economical. When thermoforming is performed immediately after coextrusion, the core remains at a high temperature, so that thermoforming is easier. The heating of the seal then only aims to maintain it at a suitable temperature, which is economical. According to a fourth aspect, the invention relates to a method of manufacturing a structure having the characteristics described above, the method comprising a step of ultrasonic welding of the core on the support. Preferably, this welding step is preceded by a step during which the seal is pre-positioned on the support. For this, the core preferably comprises a plurality of orifices spaced from one another longitudinally. The support comprises a plurality of pads, adapted to engage in the orifices. The positioning of the seal on the support is performed by engaging the orifices on the pads. The seal is thus locked in a position adapted to perform the welding. This position corresponds to the final position of the seal on the support. Pre-positioning is also achieved by engaging a portion of the support between the two upstanding edges defined by the U-section of the core. When the seal comprises two longitudinal sealing members, parallel to each other, the orifices are formed in the core, in a longitudinal strip located between the two sealing elements. Moreover, the zone of the ultrasound welded core on the support also extends in said band. Preferably, the seal has several ultrasonically welded zones on the support, distributed longitudinally along the core, for example distributed between the orifices intended for the pre-positioning of the seal on the support. Other features and advantages of the invention will emerge from the detailed description given below, by way of indication and in no way limiting, with reference to the appended figures, in which: FIG. 1 is a perspective view of a seal according to the invention; - Figure 2 is an elevational view, on the side of the sealing lips, the seal of Figure 1; - Figure 3 is a sectional view taken according to the incidence of arrows III of Figure 2; - Figure 4 is a perspective view showing the seal of Figure 1 in position on its support; and - Figure 5 is a simplified schematic representation of the seal thermoforming step.

The seal shown in FIG. 1 comprises a core 3, lower and upper lips 5 and 7, rigidly fixed to the core 3, and an upper bead 9, also rigidly attached to the core 3. The core 3 presents an elongated shape longitudinally. The core 3, seen in section in a transverse plane, has a U-section, visible in FIG. 3. The U-section is open to the left in the representation of FIG. 3. More precisely, the core 3 presents a substantially flat central web 11, and two raised edges 13 and 15. In the representation of Figure 3, the central web 11 extends in a substantially vertical plane. The upstanding edges 13 and 15 are respectively integral with the upper and lower edges of the central web 11 and substantially perpendicular to it. The raised edges 13 and 15 have a small height compared to the width of the main web 11. Here, the width of the main web 11 is taken to mean the dimension taken along the vertical direction in FIG. 3. As can be seen in FIG. The core has a first substantially rectilinear longitudinal section 17, and a second longitudinal section 19 having a longitudinal curvature. The section 17 extends from a first longitudinal end 21 of the core, over substantially half the longitudinal length of said core. The section 19 longitudinally extends the section 17 to the second longitudinal end 23 of the core. The section 19 has an upward concavity of Figure 2, that is, the side of the upright upper edge 13. The curvature is not constant along the second section 19. The lower and upper lips 5 and 7 are rigidly attached to a large face 25 of the central web 11 (Figure 3). They extend one and the other along the whole longitudinal length of the soul. The large face 25 is turned towards the outside of the U, that is to say opposite the upright edges 13 and 15. The bead 9 covers the erected edge 13. More specifically, it covers the side of the edge The bead 9 extends over the entire longitudinal length of the core 3. The lips 5 and 7, and the bead 9 are made of EPDM.

In order to allow the pre-positioning of the seal 1 on its support, before welding, the core 3 has a plurality of orifices 27, distributed longitudinally along the joint (Figures 1 and 4). The orifices 27 are formed in the central web 11 of the soul, they pass through its entire thickness. They open into the band between the two lips 5 and 7, as shown in Figure 4.

Figure 4 shows a portion of an opening of a motor vehicle. This opening comprises a structure 29 defining an opening to be closed by a not shown ice. The seal 1 is attached to the structure 29. More precisely, as shown in FIG. 4, the structure 29 comprises a substantially flat and horizontal wall 31 in the representation of FIG. 4, and a wing 33 extending the wall 31 downwards. . The seal 1 is attached along the flange 33. The upright upper edge 13 is placed against an upper face of the wall 31, on an edge zone 34. The upright edge 15 is placed against a free edge 35 of the wing 33, opposite the wall 31. Thus, the central web 11 extends substantially parallel and vis-à-vis the wing 33. The seal 1 is thus engaged in force around the wing 33 , which helps to pre-position the seal on the structure 29. In addition, the wing 33 carries a number of pads 37, projecting from the wing 33 to the sail 11. These pads 37 are engaged each in a hole 27. The pads 37 thus cooperate with the orifices 27 to contribute to the pre-positioning of the seal on the support 29.

In addition, the seal 1 is welded to the structure 29 in areas 39. More specifically, the web 11 of the core is welded to the flange 33 via the pads 37 around the orifice 27. The weld is an ultrasonic weld. The zones 39 are distributed longitudinally along the length of the core 3. The zones 39 are situated in the longitudinal band of the web 11 situated between the lower and upper lips 5 and 7, as shown in FIG. 4. As also shown in FIG. 4, the bead 9 is located above the upper face of the wall 31. It masks the upper erected edge 13. It is also placed on the upper face of the wall 31. In another embodiment (not shown), the bead 9 and the lower and upper lips 5 and 7 are connected to one another, so as to cover the core 3 on the side of the large face 25 facing towards the outside of the U. The method of manufacturing the seal described herein above will now be detailed. The first step consists of producing a rectilinear joint, by coextrusion of the core 3, of the lower and upper lips 5 and 7 and of the bead 9. This straight joint is shown in phantom in FIG.

Then, during a second step shown in Figure 5, the rectilinear seal is subjected to a thermoforming operation, to give it a longitudinal curvature. More specifically, the thermoforming step makes it possible to give the section 19 of the core a longitudinal curvature. The thermoforming operation is carried out in a dedicated thermoforming device, comprising a cavity 41, a roller 43 intended to urge the rectilinear seal against the cavity 41, a device 45 designed to move the roller 43 longitudinally along the joint and transversely to the latter so as to press the seal against the impression 41, and a heater 47 provided for heating the seal during the thermoforming operation. The impression 41 has towards the rectilinear joint 1 a forming surface 49, having longitudinally a profile corresponding to the longitudinal curvature to be produced. The roller 43 is adapted to roll against the upright edge 15 of the core by biasing the seal toward the forming surface 49 parallel to the plane of the web 11. It thus forces the bead 9 to come into contact with the surface 49, by deformation The device also comprises members (not shown) for locking in position and preventing the deformation of the section 17 of the core, so that, along the section 19, the plating of the element 9 against the forming surface 49 results from a plastic deformation of the core. The roller 43 rolls along the web, from one end of the section 17 along the section 19 to the end 23. During this deformation operation, the core 3 is heated by the radiation device infrared 47, up to a temperature suitable for performing the thermoforming operation. This temperature is a function of the material constituting the core 3. The device 45 provided for moving the roller 43 is for example pneumatic or hydraulic. The thermoforming step is typically performed immediately after the extrusion step, so that the core has not had time to cool excessively before thermoforming. The assembly of the seal on the structure of the motor vehicle is carried out as follows. The seal 1 is first pre-positioned on the structure 29, engaging the upright edges 13 and 15 on either side of the wing 33, and engaging the pads 37 in the orifices 27. The seal 1 is is then in a suitable position for welding, corresponding to its final position. The welding is then performed using ultrasonic welding equipment, along the zones 39. The ultrasonic welding technique is particularly interesting because it is already used to mount other parts on the same structure. of the motor vehicle, so that the same equipment can be used.

Claims (10)

REVENDICATIONS1. Seal for a motor vehicle, the seal (1) comprising a core (3) having a longitudinally elongated shape, and at least one sealing element (5, 7) rigidly fixed to the core (3), characterized in that core (3) is made of a first plastic material, and the sealing element (5, 7) of a second plastic material different from the first plastic material and more flexible than the first plastic material. 2. Joint according to claim 1, characterized in that the core (3) has a longitudinal curvature. 3. Seal according to any one of the preceding claims, characterized in that the core (3) has a U-section in a transverse plane. 4. Joint according to any one of the preceding claims, characterized in that the core comprises orifices (27) spaced from each other longitudinally, provided for the positioning of the seal (1) on a support (29). Seal according to any one of the preceding claims, characterized in that the first plastic material comprises a polypropylene, preferably a polypropylene. 6. Motor vehicle structure comprising a seal (1) according to any one of the preceding claims, and a support (29) on which the seal (1) is welded. 20 7. A method of manufacturing a seal according to any one of claims 1 to 5, the method comprising a thermoforming step provided to impart a longitudinal curvature to the core (3). 8. Method according to claim 7, characterized in that it comprises, before the thermoforming step, a coextrusion step of the core (3) and sealing member (5, 7). 9. The method of claim 7 or 8, characterized in that the thermoforming step is performed by biasing the seal (1) against a cavity (41) with a roller (43). 10. A method of manufacturing a structure according to claim 6, the method comprising a step of ultrasonic welding of the core (3) on the support (29).