Patent Application
20060010778
This application generally relates to a composite strip comprised of a first or flexible member formed from a first material and a second material having a desired hardness and applied on selected areas of the flexible member to maintain flexibility of the composite structure.
The composite structure finds particular application as a weatherstrip used in association with motor vehicles, such as a belt seal or glass run, or similar weatherstrip arrangement where contact with a window, and particularly in a region of a dynamic contact with the window, requires flexibility and a hard wear surface.
It is known to provide a generally U-shaped or C-shaped rigid channel in which a similarly contoured C-shaped extrusion is inserted, or where selected portions of the channel are coated with an elastomer to serve as a glass run. For example, a thermoplastic elastomer or EPDM is extruded onto the channel to form one or more flexible seal lips and on the base portion of the channel for wear purposes. The open region or cavity of the glass run receives and guides an edge of a window as the window is selectively raised and lowered relative to a vehicle door.
It is important to maintain flexibility of the composite structure, for example, where the weatherstrip is a glass run having sealing lips that flex inwardly from the outer terminal edges of the channel. A hard coating is typically applied to the flexible member such as an EPDM material, and the coating is adhesively secured to the EPDM or co-extruded therewith. The coating is usually applied over the entire surface of the EPDM and provides the desired wear characteristics of a low friction coating, although the flexibility of the structure is substantially reduced. That is, improved wear characteristics are achieved by applying a thicker coating, while the desired flexibility suggests that a thinner coat be applied. Thus, in the end, either wearability or durability is potentially compromised or sealability becomes an issue if the flexibility is sacrificed.
Conequently, a need exists for a composite structure or weatherstrip in which both of these goals are achieved without adversely impacting on performance characteristics, and that can be manufactured in an efficient and cost effective manner.
A composite structure includes an elongated flexible member having a first surface, at least a portion of which is adapted for engagement with an associated motor vehicle window. A low-friction material is disposed in longitudinal rows on the first surface.
The longitudinal rows are preferably substantially parallel along the length of the flexible member.
The low-friction material extends outwardly from the first surface of the flexible member.
In a preferred embodiment, the low-friction material has a variable thickness and the individual rows are separated or segregated so that the flexible member is capable of selectively articulating along the segregated regions.
The low-friction material has a maximum thickness on the order of 0.250 mm.
A method of forming a weatherstrip comprises the steps of forming an elongated flexible member and extruding first and second rows of a low-friction material on a first surface of the flexible member.
The flexible member forming step preferably includes the step of extruding the flexible member.
A primary benefit of the invention is the ability to provide a hard surface that does not have the same drag characteristics as a rubber, and does not lose its flexiblity. The preferred weatherstrip allows increased thickness of the hard or rigid material without impacting the flexibility of the composite weatherstrip.
Alternating peaks and valleys where the peaks are a hard material and the valleys are the flexible first material provides durability and flexibility, respectively.
The center-to-center spacing of the peaks may vary, and likewise the height of the extruded peaks can also vary depending on the material used.
Yet another advantage of the invention relates to the ease in manufacturing the weatherstrip.
Still other features and benefits of the invention will become apparent to those skilled in the art upon reading and understanding the following description.
The vehicle 10 includes door 12 that is conventionally provided with a weatherseal assembly 14, comprised of a header portion 16 that seals along the upper edge of window 18, A and B pillar portions 20, 22, respectively, and belt seal 24. Of course, the other seals described above are also included in a motor vehicle, but for purposes of brevity are not described in greater detail herein. As shown in
Receipt of the window between the flexible lips is illustrated in
As shown in
Each weatherstrip or flexible lip includes a first elongated flexible member 84 having a first or outwardly extending surface 86 and a second or inwardly facing surface 88. The seal lips are thus cantilever mounted and an inner, terminal edge 90 is free to flex or pivot relative to the mounting region of the first end 82. As will be appreciated from a review of
The present invention as exhibited in the preferred embodiment achieves both flexibility and wearability by providing a space or gap 92 between regions 94 of the low-friction material. In the preferred arrangement, the low-friction material is extruded as longitudinal rows on the first surface of the flexible member. Thus, the flexible member is preferably formed of an elastomeric material, such as rubber or EPDM, because of the desired flexibility characteristics. The low-friction material, on the other hand, is a thermoplastic or other material and is preferably coextruded on the flexible member. Longitudinally extending ridges are separated by gaps of no low-friction material, whereby the seal lip can still flex in these regions absent of any low-friction material. Advantageously, the thickness of the low-friction material coextruded on the first surface of the flexible member can be substantially increased. For example, the thickness may be increased up to a thickness on the order of one hundred twenty microns (0.120 mm). The increased thickness substantially increases the wearability of the seal lips and yet the same flexibility is maintained with the present invention because of the gaps provided between the rows of low-friction material.
As perhaps best exemplified in
Referring again to
As noted, a preferred manner of forming the assembly is to co-extrude the flexible member and the low-friction material, and preferably the low-friction material is not a coating; rather the second material is only applied on selected regions of the first material. Because of the ease with which the materials may be co-extruded, it will be appreciated that the low-friction material will typically extend in longitudinal rows that are spaced apart on the first surface of the flexible member. This should not, however, preclude the application of low-friction materials in other manners, e.g., discontinuous rows via molding, etc.
Moreover, the particular material used as the low friction material or thermoplastic material can also be wide ranging. For example, thermoplastics, thermosets, TPEs or UHMW polyethylene are materials that exhibit suitable hardness and also exhibit the desired low-friction are suitable. It is also contemplated that the low-friction material may include particles that provide a sufficient roughness that also reduces friction between the seal lip and the window.
As noted above, this invention should not be limited to just a glass run, but may also find application in other areas, whether they be dynamic or static engagement with a window or other surface. Thus, use in a glass run is evident from this description but should not so limit the claims since it is understood by one skilled in the art that use as a belt seal and in other regions where desired characteristics of a hard surface having low friction can be combined with a flexible nature desired of the underlying flexible material. It will also be appreciated that the low-friction material 96 provided on the base surface 68 of the glass run channel need not incorporate these features because flexibility is not a primary concern. However, application of a hard material in elongated strips or regions having gaps or spaced therebetween can still be supplied by reaching a desired thickness with a lesser amount of the low-friction material and thereby resulting in an overall reduction in the amount of low-friction material used in the component.
Still another example of use of the present invention relates to a door seal or primary seal having a trim lip associated with the seal. The trim lip typically extends over a scuff plate, header, etc. to provide a neat, aesthetically pleasing appearance. With increased use of side air bags, it is desirable to reduce the coefficient of friction associated with the trim lip and maintain the flexibility of the trim lip so as not to adversely impinge on deployment of the air bag. By incorporating the low friction material on a trim lip, the desired characteristics of a hard surface low friction surface that is advantageously flexible to meet the contours of the interior trim are satisfied. Likewise, ease of manufacture is still present, particularly where the primary seal and trim lip are co-extruded, and the low friction material can be co-extruded in longitudinal rows over a desired portion of the trim lip.
The invention has been described with reference to the preferred embodiments. Of course, modifications and alterations will become apparent to those of ordinary skill in the art, and the invention should not be limited to the described embodiments.
