Patent Publication Number: US-2021190114-A1

Title: Grommet for attaching cover and cover

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of PCT/JP2019/035944, filed on Sep. 12, 2019, and is related to and claims priority from Japanese patent application no. 2018-176435, filed on Sep. 20, 2018. The entire contents of the aforementioned application are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a grommet for attaching a cover used to mount a soundproof cover on a body to be covered of an engine or the like of an automobile, and a cover using the grommet. 
     Related Art 
     For example, a soundproof engine cover is attached to an engine of an automobile. As disclosed in Patent Literature 1 (Japanese Patent No. 6073610) and Patent Literature 2 (Japanese Patent Application Laid-Open No. 2006-336743), an engine cover holds an attachment member or a grommet opening downward and formed of rubber in a plurality of receiving sections protruding from a back surface. The engine cover is mounted by pushing the attachment member or the grommet against an attachment pin such as a ball stud or the like protruding from the surface of the engine. In particular, while the attachment member is formed integrally with the engine cover in Patent Literature 1 and the grommet is fitted into the receiving section, which is a separate body, in Patent Literature 2, a slit is formed in the grommet, and reduction in a load when the attachment pin is pushed thereinto is achieved. 
     When the grommet is formed of rubber while the cover is formed of a urethane having a high soundproofing property, since an adhesive property between the urethane and the rubber is poor, adhesion processing of a primer or the like is required, which increases man-hours and leads to an increase in cost. When the grommet is formed of a urethane and a resin having an adhesive property, while the adhesion processing is not required and it leads to a reduction in weight, since a resin product is not compressively deformed like the rubber, a large amount of force is required to fit or remove the attachment pin, which may deteriorate workability for attachment/detachment and may damage the grommet due to excessive pushing or pulling upon attachment and detachment. 
     SUMMARY 
     Here, the present disclosure provides a grommet for attaching a cover and a cover that are capable of accomplishing reductions in weight and cost by improving workability for attachment/detachment of the cover. 
     According to one embodiment of the disclosure, provided is a grommet for attaching a cover formed integrally with an attachment part protruding from a back surface of a cover main body and to which a tip end portion of an attachment pin provided on a body to be covered is fitted, the grommet for attaching a cover including: a concave part into which the tip end portion is fitted, and a pull-out prevention part buried in the attachment part and configured to prevent pulling out from the attachment part, wherein the concave part includes an open end portion having an inner diameter that is greater than an outer diameter of the tip end portion, a fitting portion connected to the open end portion and having an inlet with a diameter equal to or smaller than the outer diameter of the tip end portion and into which the tip end portion is fitted, and a plurality of slits formed in a fitting direction of the attachment pin from the open end portion and disposed at predetermined interval in a circumferential direction of the concave part, and the pull-out prevention part includes a plurality of first ribs disposed on extension lines of the slits. 
     According to another embodiment of the disclosure, provided is a cover including a cover main body, and a plurality of attachment parts protruding from a back surface of the cover main body to correspond to attachment pins provided on a body to be covered, wherein the grommet for attaching a cover of the above embodiments is formed integrally with each of the attachment parts. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view for describing a state in which an engine cover is mounted on an engine. 
         FIG. 2  is an exploded perspective view showing removal of a protrusion on the side of the engine and a grommet for attaching a cover. 
         FIG. 3  is a perspective view of the grommet for attaching a cover. 
         FIG. 4  is a view for describing the grommet for attaching a cover, (A) is a plan view, (B) is a front view, and (C) is a bottom view when an open end side is directed upward. 
         FIG. 5  is an enlarged cross-sectional view of  FIG. 4 , (A) is taken along line A-A in  FIG. 4 , and (B) is taken along line B-B in  FIG. 4 . 
         FIG. 6  is a view for describing a state in which the engine cover is mounted on the engine. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. 
       FIG. 1  is a view for describing a state in which an engine cover  1  that is an example of a cover is mounted on an engine  20  that is a body to be covered. First, a plurality of (only one is shown in  FIG. 1 ) protrusions  21 ,  21  . . . for attachment of the engine cover  1  protrude from a surface of the engine  20 , and a ball stud  22  serving as a metal attachment pin having a tip end portion  23  with a spherical shape protrudes from each of the protrusions  21 . 
     Meanwhile, the engine cover  1  has a cover main body  2  formed of a urethane and configured to cover a surface of the engine  20  in a non-contact manner, a plurality of (only one is shown in  FIG. 1 ) attachment parts  3 ,  3  . . . protruding downward from a back surface of the cover main body  2  to match positions of the ball studs  22 , and a grommet for attaching a cover (hereinafter, simply referred to as “a grommet”)  4  is held on each of the attachment parts  3 . 
     The grommet  4  is formed of a urethane and a integrally foamable thermoplastic resin (for example, PA6, PC/PET, ABS, or the like) having an adhesive property, and as also shown in  FIG. 2 , has a rod shape with a diameter that is gradually increased from an upper end to a lower end. A concave part  5  into which the tip end portion  23  of the ball stud  22  can be fitted is formed in a lower end of the grommet  4  on an enlarged diameter side, and a pull-out prevention part  6  buried in the attachment part  3  and configured to prevent the attachment part  3  from being pulled out is formed at an upper end on a reduced diameter side. 
     First, as shown in  FIGS. 3 to 5 , the concave part  5  includes an open end portion  7  that opens with a diameter greater than an outer diameter of the tip end portion  23  of the ball stud  22 , and a fitting portion  8  connected to the open end portion  7  and having an inlet  9  with a diameter smaller than the outer diameter of the tip end portion  23  and into which the tip end portion  23  is fitted. An inner surface of the open end portion  7  is constituted by an equal-diameter surface  10  having a diameter greater than the outer diameter of the tip end portion  23  and a tapered surface  11  having a diameter that is gradually reduced from the equal-diameter surface  10  toward the inlet  9 . A projection  12  is formed on an outer circumference of the open end portion  7 . 
     Then, as shown in  FIGS. 4 and 5 , four slits  13 ,  13  . . . , which are cut from the open end portion  7  in an axial direction to reach the fitting portion  8  are formed in the concave part  5  at equal intervals in a circumferential direction. A width of each of the slits  13  is formed in a tapered shape such that a starting end on the side of the open end portion  7  is widest and a terminal end reaching the fitting portion  8  is narrowest. 
     Next, the pull-out prevention part  6  is formed in a + shape in a lateral cross section having four first ribs  14 ,  14  . . . extending radially from an axial center of the grommet  4  in the radial direction, and the first ribs  14  are continuously formed from terminal ends of the slits  13  according to phases of the slits  13  of the concave part  5 , and are disposed on extensions of the slits  13  in the axial direction. In addition, four second ribs  15 ,  15  . . . that connect the first ribs  14  and  14  adjacent to each other in the circumferential direction are formed in the circumferential direction on a substantially intermediate section of the pull-out prevention part  6  in the axial direction. 
     In addition, each of the first ribs  14  has a protrusion amount that is reduced in the radial direction such that an outer diameter of the pull-out prevention part  6  is gradually reduced toward a side opposite to the concave part  5 , and is connected to a circular plate section  16  having a diameter greater than the outer diameter by an outer surface of each of the first ribs  14  in the radial direction at an end portion on the side opposite to the pull-out prevention part  6 . 
     In the grommet  4  and the engine cover  1  configured as described above, the grommet  4  is formed integrally with each of the attachment parts  3  when the engine cover  1  is formed by foaming a urethane. Here, as shown in  FIG. 1 , the grommet  4  is formed integrally such that the projection  12  of the outer circumference of the concave part  5  is disposed on the protruding surface of the attachment part  3 . That is, the open end portion  7  protrudes slightly from the end surface of the attachment part  3 . Accordingly, the grommet  4  is integrated with the attachment part  3  in a state in which the grommet  4  is prevented from being removed and rotated by the first ribs  14 , the second ribs  15  and the circular plate section  16  by securing elastic deformation of the concave part  5  and burying the entire pull-out prevention part  6  in the attachment part  3 . 
     In this way, the engine cover  1  that holds the grommet  4  aligns a position of each of the attachment parts  3  with each of the ball studs  22  provided on the engine  20  and pushes each of the attachment parts  3  toward the engine  20 . Then, the tip end portion  23  of the ball stud  22  enters the equal-diameter surface  10  from the open end portion  7  of the grommet  4 , and is guided to the inlet  9  by the tapered surface  11 . Here, since elastic deformation is allowed in the concave part  5  by the slits  13  while the tip end portion  23  abuts the inlet  9 , the tip end portion  23  relatively spreads the inlet  9  to enter the fitting portion  8 . After that, as shown in  FIG. 6 , the concave part  5  returns to its original shape and the inlet  9  is locked to a root side of the tip end portion  23  to hold the tip end portion  23 . Here, when the inlet  9  passes the tip end portion  23  and returns to its original shape, a good fitting feeling can be obtained. Accordingly, each of the ball studs  22  is connected to one of the grommets  4  and attachment of the engine cover  1  is completed. 
     Meanwhile, when the engine cover  1  is removed, each of the attachment parts  3  of the engine cover  1  is pulled away from the ball stud  22  and the tip end portion  23  is removed from the grommet  4 . Here, since the grommet  4  is integrated with the attachment part  3  also by the second ribs  15  and the circular plate section  16  in addition to the first ribs  14 , resistance in a pull-out direction is increased, and it is unlikely that the grommet  4  will come off the attachment part  3  and remain on the ball stud  22 . 
     In this way, according to the grommet  4  and the engine cover  1  of the aspect, the concave part  5  of the grommet  4  includes the open end portion  7  having an inner diameter greater than an outer diameter of the tip end portion  23  of the ball stud  22 , the fitting portion  8  connected to the open end portion  7  and having the inlet  9  with a diameter smaller than the outer diameter of the tip end portion  23  and into which the tip end portion  23  is fitted, and the plurality of slits  13  formed in a fitting direction of the ball stud  22  from the open end portion  7  and disposed at a predetermined interval in the circumferential direction of the concave part  5 , the pull-out prevention part  6  includes the plurality of first ribs  14  disposed on extension lines of the slits  13 , and thus elastic deformation of the concave part  5  due to the slits  13  can be secured and workability for attachment/detachment of the engine cover  1  is improved. In addition, since molding by the resin is also possible, a reduction in weight can be accomplished, a resin having a high adhesive property with respect to the engine cover  1  formed of a urethane can be selected, adhesion processing is not required, and a reduction in cost can also be accomplished. 
     In particular, here, since the first ribs  14  are formed to be continuous with the slits  13 , end portions of the slits  13  are reinforced by the first ribs  14 . 
     In addition, since the second ribs  15  that connect the first ribs  14  and  14  adjacent to each other in the circumferential direction of the pull-out prevention part  6  in the circumferential direction are formed on the pull-out prevention part  6 , the pull-out prevention part  6  is reinforced and a resistance in the pull-out direction is also increased. 
     Further, since the tapered surface  11  having an inner diameter that is gradually reduced toward the inlet  9  of the fitting portion  8  is formed on the inner surface of the open end portion  7 , the tip end portion  23  of the ball stud  22  is smoothly guided to the inlet  9 , and workability related to mounting of the engine cover  1  is further improved. 
     Meanwhile, since the concave part  5  and the pull-out prevention part  6  are formed of a thermoplastic resin, a high adhesive property can be obtained even in the engine cover  1  formed of the urethane. 
     In addition, since the four slits  13  are set and have a width that is gradually reduced from the open end portion  7  toward the fitting portion  8 , large elastic deformation can be secured on the side of the open end portion  7 . 
     Further, since the engine cover  1  is formed of the urethane, it leads to a further reduction in weight. 
     Further, while the first rib is formed to be continuous with the slit in this aspect, the first rib may be formed discontinuously with the slit. In this case, the slit can be formed short and the strength of the concave part can be maintained. 
     In addition, the slit is not limited by the fitting portion and may be lengthily extended to the pull-out prevention part. In this case, the slit can be lengthily formed to largely elastically deform the concave part. 
     Further, the structure of the concave part is likewise not limited to the aspect, and it is also possible for the tapered surface of the open end portion to be omitted or the number of slits to be increased or decreased. The diameter of the inlet of the concave part may be made equal to the outer diameter of the tip end portion of the ball stud. Also, in the pull-out prevention part, the second ribs may be omitted, or on the other hand, the plurality of second ribs may be formed at predetermined intervals in the axial direction. 
     Then, the grommet of the present disclosure can also be employed in the attachment pin instead of the ball stud having the tip end portion that is spherical. In this case, the shape of the concave part may be a square tube or the like according to the tip end portion of the attachment pin. 
     In addition, the present disclosure is not limited to the engine of the automobile as the body to be covered and is applicable to another mechanical device such as a compressor, a speed reducer, a pump, a motor, or the like, as long as the present disclosure is a cover provided for the purpose of soundproofing. 
     Other Configurations 
     According to one embodiment of the disclosure, provided is a grommet for attaching a cover formed integrally with an attachment part protruding from a back surface of a cover main body and to which a tip end portion of an attachment pin provided on a body to be covered is fitted, the grommet for attaching a cover including: a concave part into which the tip end portion is fitted, and a pull-out prevention part buried in the attachment part and configured to prevent pulling out from the attachment part, wherein the concave part includes an open end portion having an inner diameter that is greater than an outer diameter of the tip end portion, a fitting portion connected to the open end portion and having an inlet with a diameter equal to or smaller than the outer diameter of the tip end portion and into which the tip end portion is fitted, and a plurality of slits formed in a fitting direction of the attachment pin from the open end portion and disposed at predetermined interval in a circumferential direction of the concave part, and the pull-out prevention part includes a plurality of first ribs disposed on extension lines of the slits. 
     According to one embodiment of the disclosure, the first rib is formed discontinuously with the slit. 
     According to one embodiment of the disclosure, the first rib is formed continuously with the slit. 
     According to one embodiment of the disclosure, the slit extends to the pull-out prevention part. 
     According to one embodiment of the disclosure, second ribs that connect the first ribs adjacent to each other in a circumferential direction of the pull-out prevention part in the circumferential direction are formed on the pull-out prevention part. 
     According to one embodiment of the disclosure, a tapered surface having an inner diameter that is gradually reduced toward the inlet of the fitting portion is formed on the inner surface of the open end portion. 
     According to one embodiment of the disclosure, the concave part and the pull-out prevention part are formed of a thermoplastic resin. 
     According to one embodiment of the disclosure, the slits are four, and have a width that is gradually reduced from the open end portion toward the fitting portion. 
     According to one embodiment of the disclosure, the cover is formed of a urethane. 
     According to another embodiment of the disclosure, provided is a cover including a cover main body, and a plurality of attachment parts protruding from a back surface of the cover main body to correspond to attachment pins provided on a body to be covered, wherein the grommet for attaching a cover of the above embodiments is formed integrally with each of the attachment parts. 
     According to one embodiment of the disclosure, the concave part of the grommet for attaching a cover includes the open end portion having an inner diameter that is greater than an outer diameter of the tip end portion of the attachment pin, the fitting portion connected to the open end portion and having an inlet with a diameter equal to or smaller than the outer diameter of the tip end portion and into which the tip end portion is fitted, and the plurality of slits formed in a fitting direction of the attachment pin from the open end portion and disposed at predetermined interval in a circumferential direction of the concave part, the pull-out prevention part includes the plurality of first ribs disposed on extension lines of the slits, and thus, elastic deformation of the concave part due to the slit can be secured, and workability for attachment/detachment of the cover is improved. In addition, since formation by the resin is also possible, a reduction in weight can be accomplished, the resin having a high adhesive property with respect to the cover formed of a urethane can be selected, and adhesion processing is not required and a reduction in cost can be accomplished. 
     According to one embodiment of the disclosure, since the first rib is formed discontinuously with the slit, the slit can be formed shortly, and strength of the concave part can be maintained. 
     According to one embodiment of the disclosure, since the first rib is formed continuously with the slit, the end portion of the slit is reinforced by the first rib. 
     According to one embodiment of the disclosure, since the slit extends to the pull-out prevention part, the slit can be more lengthily formed to largely elastically deform the concave part. 
     According to one embodiment of the disclosure, since the second ribs that connect the first ribs adjacent to each other in a circumferential direction of the pull-out prevention part in the circumferential direction are formed on the pull-out prevention part, the pull-out prevention part is reinforced, and a resistance in a pull-out direction is also increased. 
     According to one embodiment of the disclosure, since the tapered surface having an inner diameter that is gradually reduced toward the inlet of the fitting portion is formed on the inner surface of the open end portion, the tip end portion of the attachment pin is smoothly guided to the inlet, and workability related to mounting of the cover is further improved. 
     According to one embodiment of the disclosure, since the concave part and the pull-out prevention part are formed of a thermoplastic resin, a high adhesive property is obtained even in the cover formed of the urethane. 
     According to one embodiment of the disclosure, since the slits are four, and have a width that is gradually reduced from the open end portion toward the fitting portion, large elastic deformation can be secured on the side of the open end portion. 
     According to one embodiment of the disclosure, since the cover is formed of the urethane, it leads to a further reduction in weight. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.