Abstract:
A grommet assembly includes a retainer including a sleeve, and a boot secured to the retainer, including a first and a second series of pleats aligned with the sleeve, each pleat of the second series decreasing in size as distance from the retainer increases, each pleat of the first series having a substantially uniform size and spaced from a consecutive pleat of the first series by a distance that is less than a space between consecutive pleats of the second series.

Description:
BACKGROUND OF INVENTION 
       [0001]    The present invention relates generally to an apparatus through which wire harnesses, cables, linkages and rods can be passed through an opening in a vehicle body component, such as a hydraulic or non-hydraulic power liftgate. 
         [0002]    Grommets are rings of metal, plastic or rubber, which are inserted into a hole made through another material to reinforce the hole or to shield something passed through the grommet from the sharp edges of the hole. Grommets also prevent fluids and gases from entering or exiting the vehicle through the hole. 
         [0003]    In a vehicle, wire harnesses, cables, linkages, hydraulic lines, rods, and other such equipment must pass from inside the vehicle body to doors, hoods and liftgates, which are supported on hinges and swing open and closed relative to the body. In such applications, there is potential for significant relative motion between the material and the pass through opening. For example, power gate struts, brake lines, linkages and hydraulic lines for a power liftgate that pass from inside to outside the vehicle need to travel back and forth through the opening when the gate is opened and closed. 
         [0004]    A conventional grommet restricts relative motion between the opening and material translating through the opening, or requires a greater length of the translating material than would be required to accommodate the motion of the door or liftgate relative to the opening. 
         [0005]    For electrical harness applications, loops are used to allow for a twisting or hinging motion that stores and provides the required length for cycling. But packaging space may not be available or the translating material may be too stiff to loop without kinking. 
         [0006]    A need exits in the industry for a pass-through grommet that allows for repeated cyclic translation of material in and out of a body opening, while protecting the sealing material from abrasion and subsequent loss of sealing. 
       SUMMARY OF INVENTION 
       [0007]    A grommet assembly includes a retainer including a sleeve, and a boot secured to the retainer, including a first and a second series of pleats aligned with the sleeve, each pleat of the second series decreasing in size as distance from the retainer increases, each pleat of the first series having a substantially uniform size and spaced from a consecutive pleat of the first series by a distance that is less than a space between consecutive pleats of the second series. 
         [0008]    The grommet provides potential for applications in which wire harnesses, cables, linkages and rods are passed through an opening in a vehicle body. The grommet allows repeated, cyclic translation of hoses in and out of a body opening while maintaining the opening sealed and the translating material protected from abrasion. 
         [0009]    The grommet has small sections and requires less space for excess material, thereby improving packaging potential compared to alternatives. The design minimizes weight and cost, and requires less rubber and wire than conventional designs. 
         [0010]    The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a cross section taken at a longitudinal plane through a grommet assembly installed in an opening; 
           [0012]      FIG. 2  is a perspective side view of the grommet assembly of  Fig. 1  ; 
           [0013]      FIG. 3  is a cross section taken through the retainer and its inner sleeve taken at plane  3 - 3  of  FIG. 1 ; and 
           [0014]      FIG. 4  is a side view of the grommet boot of  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Referring now to the drawings, there is illustrated in  FIG. 1  a two piece grommet assembly  10 , which includes a retainer  12  having an inner sleeve  14  for guiding the translating material  15 , and a pleated grommet boot  16 . The retainer  12  and boot  16  are aligned about an axis  17 . Sleeve  14  guides the translating material  15  through an opening  18  in a wall  20  and prevents significant sliding contact between the translating material and the boot  16 . The retainer guides and directs the material controlling its shape as it translates. Some minimal contact may take place between the boot and material, but that contact occurs under the low load required to deflect the boot to the path or shape of the translating material throughout its travel. 
         [0016]    The translating material could be rods, flexible high-pressure lines, or bundles containing a wire harness, hoses or conduits, high-pressure lines or tubing. The opening  18  is formed in an external panel  32  of a vehicle body. 
         [0017]    The grommet boot  16  is a molding formed preferably of ethylene propylene diene M-class rubber (EPDM). 
         [0018]    Boot  16  comprises a compressible portion that includes a series of pleats  20  that are tapered along the length of the boot to prevent or minimize contact with the translating media  15 . The taper pleats  20  also prevent the grommet  10  from collapsing on itself during compression. 
         [0019]    Boot  16  further comprises a series of smaller diameter pleats  22  along a length of the boot  16  where little relative motion occurs between the translating material  15  and the boot  16 . The relatively small size of the pleats  22  guides the translating material  15  preventing significant contact with the boot pleats  20  in the compressible area, where the highest relative motion occurs between the boot  16  and the translating material  15 . The boot pleats  22  provide flexibility and allow minimal compression. 
         [0020]    The retainer  12  includes an inner sleeve  14 , outer sleeve  24 , stop  26  and ring  26 , molded as one integral component of the grommet assembly  10 . Ring  26 , located at the end of the outer sleeve  24 , is fitted into a recess  28 , molded integrally in the grommet boot  16 , thereby securing the retainer  12  to the boot  16 . The stop  26  has a tapered surface  30 , which facilitates pushing the retainer  12  through the opening  18  from the right-hand side of the wall  20 . 
         [0021]    The left-hand side  32  of wall  20  is forced elastically into contact with the end face  34  of stop  26  due to compressing the lip  36 , located at the end of the grommet boot  16 , against the right-hand side  38  of wall  20 . Contact between lip  36  and wall  20  provides an elastic seal that prevents passage of extraneous material into the boot  16 . 
         [0022]    The retainer  12  creates a predictable deflection of the translating material  15  as it oscillates in the boot  16  as a door or liftgate is opened and closed in service. Retainer  12  is a molded component preferably of plastic such as Nylon or acetel having a lower coefficient of friction than that of the EPDM boot  16 . 
         [0023]      FIG. 2  shows that the right-hand end of boot  16  supports a plug or interface  40 , formed integrally with the boot  16 , the plug  40  having two longitudinal passages, through which the translating material exits the boot  16 . The first passage is formed with an annular bead  42 , which frictionally engages the translating material in the first passage. The second passage is formed with an annular bead  44 , which frictionally engages the translating material in the second passage. 
         [0024]    As  FIG. 3  illustrates, the cross section through the retainer  1   2  and its inner sleeve  14  has an oblong shape, i.e., two straight sides  46 ,  48  connected by arcuate surfaces  50 ,  52 . 
         [0025]      FIG. 4  illustrates the grommet boot  16  without the retainer  12 . 
         [0026]    Preferably the thickness  60  of the translating material  15  is less than the distance between surfaces  48 ,  48  of the inner sleeve  14 , and the width of the translating material is less than the distance  64  between surfaces  50 ,  52  of the inner sleeve. Preferably the thickness  60  of the translating material  15  is about the same or slightly less that the distance  66  between the valleys  68  of the boot pleats  22  and less than the distance  70  between the valleys  72  of the boot pleats  20 . 
         [0027]    The optional smaller boot pleats  22  prevent buckling of the boot by allowing compression on the inside surface and extension on the outside surface during bending. The distance  66  between the smaller boot pleats  22  control the relative position between the boot pleats  20  and the translating material  15  during the deflection of the translating material  15  as it oscillates in the boot  16  through the opening  18 . The larger boot pleats  20  are sized with respect their diameter, wall thickness and distance between successive pleats such that the pleats  22  remain stable and support one another against collapse when a compressive force is applied to the boot  16  as the translating material  15  bends and or oscillates in the boot  16  through the opening  18  when the door or liftgate opens and closes. 
         [0028]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.