Magnetic gasket suitable in particular for forming a seal between a fixed part, such as motor vehicle body, and an openable part, such as the door in regions of curvilinear extension

Abstract: This invention relates to a magnetic gasket particularly suitable for forming a seal between a fixed part and an openable part in regions of curvilinear extension, for example in particular between the body and door (3) of a vehicle, of the type comprising an profiled strip (4) for fixing to said parts and a tubular seat housing (10) a magnetized insert (11), characterised in that said profiled fixing strip (4) and said tubular seat (8) for the magnetized insert (11) are connected together by an extendable deformable tubular chamber (10) the opposing free walls (12,13) of which are substantially curvilinear and curved in the same direction.

Description: Gaskets for motor vehicles are known, for example from the Italian patent IT-A-1,107,502 and French utility model FR-U-2 545 145 in the name of the present applicant, which are suitable for forming a seal between the vehicle body and openable parts of the bodywork, such as doors, hatches, hood and the like when these are closed, of the type comprising a deformable profiled strip able to be fixed to the vehicle body by snapping-on, to said profiled strip there being connected along the straight regions of engagement between the vehicle body and the openable part a tubular section divided into a pair of separate adjacent chambers, one of which acts as a bellows air chamber and the other as a seat for magnetized material. EP-A-0 369 799 relates to a magnetic window seal assembly for frameless and full flush window systems of automotive vehicles comprising a flexible sealing strip having a compressible body portion with a first magnetic element embedded therein mounted to the vehicle body. A complementary second magnetic element is provided on the lateral edge of the window being sealed. These magnetic gaskets represent a considerable progress over compression-operated gaskets without a magnetic seal, in terms both of improved sealing and of lesser pulling action to effect closure. There is however the technical problem of adapting this type of gasket to the various range of shapes which the engagement region between the fixed and openable parts can assume, particularly in curvilinear regions, and especially when the radius of curvature is small. In very accentuated curvature regions there are considerable problems relating to deformation and squashing of the magnetic gaskets, which can result in loss of seal, formation of folds and points of discontinuity, or indeed breakage of the gasket after a certain time. The main object of the present invention is to provide a magnetic gasket of the type disclosed e.g. in EP-A-0 369 799 both for motor vehicles and for other systems in which a seal is required between a fixed part and an openable part, such as refrigerators, freezers, windows, cabins etc., which is substantially universal, ie can be easily adapted to every possible shape of the engagement region between the fixed part and openable part on which the gasket is to operate, including in regions of accentuated curvature. A further object is to achieve this while maintaining the essential characteristic of magnetic gaskets, ie of easy extensibility along a direction perpendicular to the sealing plane between the fixed part and openable part, so as to compensate for any possible lack of planarity. These objects are attained according to the present invention by a magnetic gasket according to claim 1. Further developments in line with the invention are referred to in the dependent claims 2 to 7. The characteristics and advantages of the invention will be more apparent from the description of some non-limiting embodiments thereof, given hereinafter with reference to the figures of the accompanying drawings. Figure 1 is a sectional pespective view of a gasket of the invention. Figure 2 is a view analogous of that of Figure 1 showing the same gasket in a different operating position. Figures 3, 4 and 5 are three sectional views of the gasket of Figures 1 and 2 at three different points, taken on the lines III-III, IV-IV and V-V of said Figures 1 and 2 respectively. Figure 6 shows a gasket in accordance with said figures operationally mounted on a motor vehicle. Figures 7 and 8 are sectional views of two further embodiments of the gasket according to the invention. In the drawings, Figures 1 to 6 show a gasket suitable for use on a vehicle, for example for sealing between the vehicle body and openable parts such as doors, boot or hood. With reference to Figure 6, along a frame 1 of a motor vehicle body cooperating with an access door 3 there is fixed a snap-on profiled strip 4 with a metal core 5 and having a C-shaped cross-section. The strip 4 is basically a ring fixed along the entire extension of the frame 1, on which it is forced and secured by the pressure exerted by the fins of the metal core, adherence being completed by the action of saw-tooth projections 6 which act on the surface of the vehicle body frame. Along the angular and curvilinear regions of the frame 1 the profiled strip 4 follows the shape because of its capacity to deform and to assume a torus development. In a direction parallel to but on the opposite side to the profiled strip 4 there extends in the direction of the door 3 a tubular seat 8 housing magnetized material, such as a plastoferrite bar 11, able to act as a magnetic pole against a counter-pole formed by the door 3 itself if this is of ferromagnetic material, or by a suitable ferromagnetic plate 9 located on the door in a position facing the bar 11, if the door is for example of plastics material. The snap-on strip 4 and the seat 8 containing the magnetic insert are connected together by an interposed tubular chamber 10, which is elastically yieldable and deformable so that it can extend as a bellows particularly in the direction perpendicular to the surface of contact with the counter-pole. The configuration of the chamber 10, when viewed in cross-section, is as follows: the two opposing walls 12 and 13 when not urged by the snap-on strip or the seat for the magnetic insert are of essentially curvilinear and parallel shape, in the sense defined hereinafter. The wall 12 is that which faces the vehicle body frame 1 and is hence that which is on the outside when operationally mounted. The wall 13 is that which is on the inside when in the operating position. The two walls 12 and 13 are therefore both curved towards the outside of the curve which the gasket assumes within the curvilinear engagement region. The wall 13 is most curvilinear in its central region, whereas in its side portions 14 and 15 connected to the snap-on strip and to the magnetic insert seat it is of rectilinear extension. From the rectilinear portion 14 there extends a rib 16 which acts as a spacer between said two portions. From the outer wall 12 there extends a corresponding spacer 17 in the direction of the frame 1. Figures 1 to 5 show the performance of the gasket according to the invention within the curvilinear engagement regions of the vehicle body. Figure 3 shows the form of the cross-section through the gasket in the region III-III in which in practice there is no deformation of the gasket, so that this cross-section corresponds basically to the nominal cross-section. Figure 1 shows a gasket deformation in the region IV-IV because of a different radius of curvature of the profile of the engagement region. The corresponding gasket cross-section shown in Figure 4 when compared with the gasket cross-section shown in Figure 3 shows a slackening, with flattening, of the outer wall 12 and a more accentuated curvature of the inner wall 13, with approach of the portions 14 and 15. In a region, such as the region V-V of Figure 2, in which there is a further reduction in the radius of curvature of the profile in the engagement region, the corresponding gasket cross-section shown in Figure 5 shows a further slackening with flattening of the outer wall 12 and a more accentuated curvature of the inner wall 13, with the portions 14 and 15 making contact via the rib 16. As will be apparent, the effect is therefore to compensate the deformations which can occur in any engagement region of the gasket by virtue of radius of curvature variations at the points concerned, so that the gasket surface always adheres perfectly to the engagement region independently of the corresponding radius of curvature, even if this is small. At the same time a sufficient gasket extendability is preserved in a direction perpendicular to the surface of contact with the counter-pole. This extendability enables the gasket to operate correctly, to compensate any planarity inaccuracies in the contact surface and ensure a seal along the entire outline. For applications relating to refrigerator, freezer and similar doors, and to windows, door frames, cabins etc., the gasket can take the form of that shown in Figures 7 and 8. Figure 7 shows the cross-section through a mono-extruded gasket of soft elastic material such as plasticized PVC, thermoplastic rubber or a traditional vulcanized elastomer housing a magnetic insert 11 in a thin tubular section 18. The fixing element is in this case a fishbone section comprising a body 19 with fins 20 for insertion into the recess in the refrigerator door abutment, or door or window frame. This recess can be formed by thermoforming in the case of a refrigerator or by milling in the case of door and window frames, with rounded corners to avoid the need for welding. The gasket can be completed by a 90° butt weld to seal at the junction point. Figure 8 shows a coextruded gasket in which the the coupling foot consists of the rigid section 21 but with fins 22 of the same soft material as the rest of the gasket. The combination of rigid and soft material can be in the form of traditional two-hardness vulcanized elastomer, rigid and soft PVC, or coextrudable thermoplastic rubber and rigid material, hence achieving perfect adhesion between rigid and soft materials (such as thermoplastic olefin rubber and polypropylene, ABS and thermoplastic styrene or polyester rubber). In both the cases shown in Figures 7 and 8, the extendable tubular chamber 10 has the characteristic structure described for the preceding examples. The operation of these gaskets of the invention is hence essentially similar to that already described with reference to Figures 1 to 6. In the case of a refrigerator cabinet or the like, the aforegoing can be extended to this application in that although it is the known art to use magnetic gaskets welded at the corners so that they follow a rectangular shape which is widespread in practice, it is possible, by suitably shaping the recesses which are to receive the coupling parts of the gasket, to apply a gasket having corners of a suitable radius of curvature so that instead of comprising four 90° welds at the corners it has only one 180° butt weld. This simplifies the refrigerator gasket and results in reduced costs. The gasket of the present invention can also be analogously applied to door and window frames, verandas or general closures in the building industry when adaptation to a certain curvature of the closure edge is required, for example in the case of doors or windows which are not completely rectangular but instead have a circular upper finish. In these cases the parallel curved-wall shape of the bellows provides the necessary curvature to the extruded section. This concept is applicable for example to the magnetic gaskets described in French utility models FR-U-2 582 043 and FR-U-2 598 744 of the present applicant. In addition, in the described fields of application the facility for following curvatures gives the stylist considerable freedom in designing the finished object, which would otherwise be dependent upon 90° or other corner welds.

Claims: A magnetic gasket particularly suitable for forming a seal between a fixed part (1) and an openable part (3) in regions of curvilinear extension, for example in particular between the body and door of a vehicle, of the type comprising a profiled strip (4) for fixing to said parts and a tubular seat (8) housing a magnetized insert (11), said profiled strip (4) and said tubular seat (8) for the magnetized insert being connected together by an extendable deformable tubular chamber (10), said chamber (10) having opposing free walls (12,13) which extend between said strip (4) and said seat (8), and which are substantially curvilinear, characterised in that the opposing free walls (12,13) are curved in cross-section in the same direction, that is towards the outside of the curve which the gasket assumes within said region of curvilinear extension. A magnetic gasket as claimed in claim 1, characterised in that the walls (13) of said extendable tubular chamber (10) which when in its operating position faces inwards the curvature of the. engagement region between the fixed part and the movable part is essentially curved in its central part, its lateral portions (14,15) being of rectilinear extension. A gasket as claimed in claim 2, characterised in that a spacer (17) extends from at least one of said rectilinear portions (14,15) towards the other. A gasket as claimed in claim 1, characterised in that in passing from an engagement region of lesser curvature to an engagement region of greater curvature said wall (13) of said extendable tubular chamber (10) which faces inwards of the curvature accentuates its curvilinear shape, whereas that (12) which faces outwards slackens to assume a flatter shape. A gasket as claimed in claim 1, characterised in that at least said wall of said extendable chamber (10) which faces the fixed part, for example the vehicle body, is provided with a spacer (17). A gasket as claimed in claim 1, characterised in that said profiled fixing strip (4), said seat (8) for the magnetic insert (11) and said extendable chamber (10) are separate parts, and are joined together by a suitable means, such as an adhesive. A gasket as claimed in claim 1, characterised in that said profiled strip (4), said seat (8) for the magnetic insert (11) and said extendable chamber (10) are moulded in one piece or coextruded.

Inventors: CITTADINI PAOLO, MERLA ADRIANO, CITTADINI, PAOLO, MERLA, ADRIANO
Applicants: ILPEA IND SPA, INDUSTRIE ILPEA S.P.A.
Application year: 1992
Main classification: B60J10
IPC codes: B60J10, F16J15