Grommet

Abstract: A grommet capable of easy installation by reducing an insertion resistance when conducting an insertion of the grommet into an opening of a vehicle panel is disclosed. The configuration of the grommet allows molds for forming the grommet to have reduced processing costs, and molding and installation time can also be decreased. The grommet includes wire harness holding areas (11, 12) for tightly engaging around the periphery of the wire harness and an engagement area (15) which fixedly engages an opening (21) provided on a vehicle panel (20). A tapered area (14) connects a wire harness holding area (11) and an engagement area (13) with a near-conical tapered surface extending over the outer surface of a tapered area, and a plurality of linear areas (15), which may be of convex or concave configuration, are provided to extend from a wire harness holding area to the engagement area, in an insertion direction of the grommet over the entire periphery on the tapered area.

Description: The present invention relates to a grommet which holds a wire harness having a route that penetrates an opening in a panel, particularly an opening in a vehicle panel, etc. Wire harness arrangement routes for vehicles have recently become more complicated and versatile as mounting of various electrical components on vehicles advances. This requires a wide use of parts for wire harness protection or maintenance, such as harness protectors for avoiding interference with peripheral parts and grommets used for penetrating through the openings provided in a vehicle panel. In particular, via an opening which is formed in a vehicle panel, a grommet formed of integrally molded rubber, etc. is generally used on a wire harness having a route, for instance, from an engine compartment to a passenger compartment or from a vehicle body to door areas, for the purpose of holding a cable arrangement route and avoiding contact with the vehicle panel and resulting damages. For example, as shown in Figure 4, a conventional grommet 10f to be mounted on a wire harness 16, which is arranged to penetrate a vehicle panel 20, includes wire harness holding areas 11 and 12 for engaging around and tightly holding the outer periphery of the harness. An engagement area 13 is provided for fixedly engaging the grommet 10f to a predetermined opening formed in the vehicle panel, and a tapered area 14 connects the wire harness holding area 11 and the engagement area 13 over a near-conical tapered area. In this case, the grommet 10f is connected to the wire harness 16 by means of fixing tapes 17 and 18 at the respective wire harness holding areas 11 and 12. The description which follows makes reference to Figures 5(a) and 5(b) regarding an insertion operation and an engaged condition relative to a panel opening in accordance with the conventional grommet 10f. As shown in Figure 5(a), when the grommet 10f, which is fixedly connected to a wire harness 16, is drawn in an insertion direction, via an opening from one side (a left side as shown in the drawing) of a vehicle panel 20, by taking a wire harness holding area side (left direction in the drawing) provided on the tapered area 14 as an inserting direction, an insertion resistance arises as a result of sliding contact at the edge areas between the tapered area 14 and an opening 21. Therefore, by further drawing the grommet 10f with a force greater than the insertion resistance, applied in the direction shown by the arrow designated F3, the engagement area 13 is fixedly engaged in the opening 21 as shown in Figure 5(b), and a predetermined route is maintained, without harness 16 making contact with the opening 21. With the conventional grommet 10f, there was a problem of considerable worsening of the mounting workability of the wire harness 16 due to an insertion resistance becoming greater as a result of sliding contact with the surface of the tapered area 14 over the entire area by the edge of the opening 21 during insertion of the grommet and harness into the opening 21. In addition, another factor increasing the insertion resistance includes the use of material having a higher deformability which lacks surface slidability such as the integrally molded rubber of the grommet 10f, which further increases the frictional resistance with the edge area of the opening 21, thereby necessitating a greater drawing force F3. One known solution to this problem is shown in the Japanese unexamined Patent Publication No. (Hei) 7-115286. Such a method as reducing a frictional resistance, or insertion resistance, by applying many minute concave/convex areas on the surface of a tapered area, namely, applying a electrical discharge process, thereby making a contact area with an edge area smaller at insertion when inserting the work into the opening. According to this known solution, a method for forming concave/convex areas on the mold die by electrical discharge machining is generally utilized to form a plurality of concave/convex areas on the tapered surface of the grommet formed from integrally molded rubber, thus forming concave/convex areas on the tapered area formed on the integrally molded rubber grommet. However, the electrical discharge machine has an extremely slow processing speed compared with the case of using normal NC processing (mechanical processing by use of cutting tools), and a problem of higher processing cost. A grommet is disclosed in JP 09069320-A having a tapered body extending between a circular groove to receive the marginal edge of an opening in which the grommet is fitted and a tubular cable receiving part of reduced diameter. A pair of ribs lead from opposite sides of the cable receiving part to the center area of the tapered body to prevent buckling of the tapered body during installation. A grommet according to the preamble of claim 1 is disclosed in JP 09082161-A having a tapered body extending between a circular groove to receive the marginal edge of an opening in which the grommet is fitted and a tubular cable receiving part of reduced diameter. The tapered body is provided with smoothing material adjacent to the groove that is configured to slidably contact an edge of the opening and reduce insertion resistance of the grommet during installation. An objective of the present invention is to provide a grommet that allows easy engagement by reducing an insertion resistance during insertion of the grommet into the opening of vehicle panel, thereby providing a grommet capable of reducing the machining cost for molding dies as well as the machining time. In order to achieve the above-mentioned objective the present invention provides a grommet as defined in claim 1. By providing linear projection areas in an insertion direction over the full periphery of the tapered area, only an upper surface of the linear projection areas makes sliding contact with the edge of the installation opening during insertion into or engagement with the predetermined opening area of the grommet. Therefore, the grommet structure of the present invention allows the insertion resistance to be reduced by reducing the contact area between the installation opening area and the grommet during insertion, also improving a mounting workability of a wire harness by reducing the drawing force required during insertion of the grommet. The linear projection areas of the grommet may be formed from a material that is harder than that forming the tapered portion, thereby further reducing the insertion resistance of the grommet. The linear projection areas may project a distance above the tapered portion so that the distance of projection tapers from a greater distance at an end thereof adjacent the engagement area to a lesser distance at the opposite end thereof. The grommet can include a second linear holder portion adapted to tightly engage around the periphery of the wire harness inserted therethrough, the second holder portion being formed on the grommet adjacent the engagement area. The grommet is not limited to any particular shape, but can be configured with an engagement area having various shapes, including circular, non-circular, generally elliptical or generally rectangular. The grommet can also be configured such that the linear projection areas are arranged to be equally spaced about the tapered portion. Furthermore, since a linear projection area is formed on the tapered area by utilizing a cutting process on a tapered area of the molding die using machining processing or a processing on the ridge area in advance. Accordingly, a grommet is extremely easily formed which has a predetermined linear projecting area within a short period of time. Thus, it is possible to control the molding die processing to be less complicated while making the processing time shorter. The above and other features and advantages of the present invention will be made apparent from the following description of the preferred embodiments, given as nonlimiting examples, with reference to the accompanying drawings, in which like reference numerals represent similar parts throughout the several views of the drawings: Figures 1 (a) and 1 (b) show a first embodiment of the grommet of the present invention. Figures 2 (a) and 2 (b) depict an insertion operation and an engaged condition of the grommet of the present invention, respectively. Figures 3 (a) and 3 (b) show another embodiment of the grommet of the present invention. Figure 4 is a drawing depicting a grommet of the prior art. Figures 5 (a) and 5 (b) show an insertion operation and an engaged condition of the grommet of the prior art, respectively. A first embodiment of the grommet of the present invention will now be described with regard to the present invention in reference to Figures 1 (a) and 1 (b). As shown in Figure 1(a) and Figure 1(b), a grommet 10a includes wire harness holding areas 11 and 12 which tightly engage and hold the outer periphery of a wire harness. An engagement area 13 is provided to fixedly engage with an installation opening provided in a vehicle panel. A tapered area 14 having a near-conical tapered shape over a full periphery thereof extends between the wire harness holding area 11 and the engagement area 13. A plurality of spaced linear projection areas or ribs 15a are provided to extend from the engagement area 13 towards the wire harness holding area 11 over the entire periphery of the tapered area 14 in an inserted direction of the grommet. The linear projection areas or ribs 15a are integrally formed with the grommet from the same material as that of the grommet. This is achieved by utilizing a machining process to form a plurality of grooves, which correspond to the linear projection areas or ribs 15a, to the molding die in the area corresponding to the tapered area 14. Therefore, the processing work can be readily accomplished within a short period of time at a lower cost. In the embodiment depicted in Figure 1 (a) and Figure 1(b), a grommet structure is shown in which each linear projection area or rib 15a is uniformly arranged on the tapered area 14. That is, each linear projection area or rib 15a has a uniform length, protruding height, convex section area, and a uniform radiating shape with uniform angle from wire harness holding area 11. As shown the protruding height of each linear projection area or rib 15a is such that a stepped end 15a' is formed adjacent to the wire harness holding area 11. Nevertheless, the present invention is not limited to this structure alone. The following description is of an insertion and engaged condition of grommet 10a with an installation opening according to the first embodiment of the invention with reference to Figures 2(a) and 2 (b). As shown in Figure 2(b), a grommet 10a, which is fixedly attached with fixing tapes 17 and 18 to the outer peripheral surface of the wire harness 16 by the wire harness holding areas 11 and 12, is inserted by applying a force to a wire harness holding area 11 (right direction in the drawing) in which a tapered area 14 is provided as an inserted direction. Only an upper surface of each linear projection area or rib 15a, which projects and extends above the remaining surface of the tapered area 14, slidably makes contact with the edge of the opening 21. In this case, since the contact area between the edge of the linear projection area or rib 15a and opening area 21 is only determined by the width of upper surface of the linear projection areas or ribs 15a, an insertion resistance is reduced when compared with a conventional grommet structure (Figures 5(a) and 5(b)) which makes contact with the edge of the opening 21 about the full periphery of the tapered area 14. Therefore, by applying an insertion force (arrow designated F1) smaller than the arrow designated F3 as shown in the conventional structure (Figure 5 (a)), an engagement area 13 of grommet 10a is fixedly engaged in the opening area 21 as shown in Figure 2(b), and a predetermined arranged route is maintained without the wire harness 16 making contact with the opening 21. Particularly, since a linear projection area or rib 15a representing the feature of the first embodiment is integrally formed on tapered area 14 from rubber or other elastomeric material, which is the same material as that of the grommet, can inhibit deformation as compared with that of other tapered area 14 due to the thickness of the region in which the linear projection areas or ribs are formed, areas 15a become thicker, and the upper surface thereof alone can slidably contact the edge of the opening 21 with good lubrication and deformation is inhibited even in the event the linear projection areas or ribs 15a have a narrow width. Moreover, while the linear projection areas or ribs 15a have been disclosed to include a structure formed integrally of rubber or other elastomeric material, which material is the same as that of grommet 10a, the present invention is not so limited. For example, by forming the linear projection areas or ribs 15a separately by using a two-color forming method, or the like, with a material harder than that of main portion of grommet 10a, the insertion resistance can by further decreased with the width of linear projection area or rib 15a being made narrower. In the above-described embodiment, although grommet 10a is shown having a tapered area 14 connecting the wire harness holding area 11 and the engagement area 13 which is near-conically formed, and the engagement area 13 is formed to have a generally circular shape, the present invention is not necessarily restricted to this configuration. For example, as shown in Figure 3(a) and Figure 3(b), the structure may include an engagement area 13 having a near elliptical shape, or a near oval shape, and the grommet 10e is formed with linear projection areas or ribs 15a. When inserting a grommet 10e within the opening 21, as long as the tapered area 14 has a shape that can make contact with the edge of the opening 21, and linear projection areas or ribs 15a are provided in an insertion direction so that the contact area between the edge and tapered area 14 of the opening area 21 is reduced, the same operational effects as those of the first embodiment can be expected. As mentioned above, according to the grommet of the present invention, by providing linear projection areas or ribs which extend in an insertion direction of the grommet over the full periphery of the tapered surface which forms the tapered area, since only the linear projection areas or ribs on the upper surface of the tapered portion slidably contact the edge of the opening when inserting or engaging the grommet of a predetermined opening area, the contact area between the grommet and the edge of the opening is reduced. Accordingly, the insertion resistance is subsequently reduced, also reducing the force upon insertion and engaging, thereby improving a workability during mounting of the wire harness. In addition, because the linear projection areas or ribs which are provided to extend on the tapered area can be formed on a grommet having a predetermined linear projection area by applying a cutting process to the tapered area of molding die using a mechanical processing, which consequently enables molding die production cost to be controlled without making the molding die processing method more complicated and increasing the production time. The advantages and improved results furnished by the method and apparatus of the present invention are apparent from the foregoing description of the preferred embodiments of the invention. Various changes and modifications may be made without departing from the scope of the invention defined in the appended claims.

Claims: A grommet comprising a linear holder portion (11) adapted tightly to engage around the periphery of a member (16) inserted therethrough, an engagement area (13) for engagement with an installation opening (21) through which said linear holder portion (11) is arranged to penetrate, a tapered portion (14) which connects said linear holder portion (11) and said engagement area (13), and a plurality of linear projection areas (15a) provided on said tapered portion (14) are configured to slidably contact an edge of the installation opening (21) during insertion, thereby reducing insertion resistance of the grommet during installation characterized in that said linear projection areas (15a) are arranged to extend from adjacent said engagement area (13) to adjacent said holder portion (11) around the entire periphery of said tapered portion (14) and have a stepped end (15a') located adjacent said holder portion (11). A grommet in accordance with claim 1, characterised in that said linear projection areas (15a) comprise linear ribs (15 a ). A grommet in accordance with claim 1 or claim 2, characterised in that said engagement area (13) is configured to be circular. A grommet in accordance with claim 3, characterised in that said linear projection areas (15) are arranged to be equally spaced about said tapered portion (14). A grommet in accordance with claim 1 or claim 2, characterised in that said engagement area (13) is configured to be non-circular. A grommet in accordance with any one of the preceding claims, characterised in that said linear projection areas (15 a ) are formed from a material that is harder than that forming said tapered portion (14), thereby further reducing the insertion resistance of the grommet. A grommet in accordance with any one of the preceding claims, characterised in that said linear projection areas (15a) project a distance above said tapered portion (14) that tapers from a greater distance at an end thereof adjacent said engagement area (13) to a lesser distance at the opposite end thereof. A grommet in accordance with any one of the preceding claims, characterised in that said linear projection areas (15a) have a uniform length, protruding height, convex section area and a uniform radiating shape with uniform angle from the holder portion (11). A grommet in accordance with any one of the preceding claims, characterised in that a second linear holder portion (12) is formed on said grommet adjacent said engagement area (13) and is adapted to tightly engage around the periphery of a member (16) inserted therethrough.

Inventors: MORI RYOUJI, SATOU MINORU, MORI, RYOUJI, SATOU, MINORU, Mori, Ryouji, c/o Sumitomo Wiring Systems Ltd.,, Satou, Minoru, c/o Sumitomo Wiring Systems Ltd.,
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1998
Main classification: B60R16
IPC codes: B60R16, H01B17, H02G3