Abstract:
A bolt fastening structure is comprised of a fastened member and a fastening seat. The fastened member has a bolt hole for inserting a bolt and a pair of slits disposed around the bolt hole. The fastening seat has a pair of leg portions and a connecting portion integrally connecting the leg portions. The leg portions have a length which is substantially as same as a depth dimension of the bolt hole of said fastened member. The leg portions are inserted to the slits, respectively. By fastening the bolt with a threaded hole of a second fastened member, upper and lower surfaces of the leg portions are fitted to a head of the bolt and the second fastened member.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to improvements in a bolt fastening structure applied to fastening between a housing of a shift lever apparatus and a shift cable bracket and fastening between the housing and a vehicle body. 
     Many shift lever apparatuses have employed a housing made of plastic resin. Usually, a shift lever apparatus is interconnected to a cable bracket for connecting a shift cable to the shift lever apparatus, by means of bolts. However, it is not preferable that a resin member is directly fastened with another member by means of bolts due to properties of plastic resin. For example, due to mechanical property of resin members a fastening force of the resin member to other member is restricted so as to avoid the resin member from being broken. Further, it is necessary to take account of loosening of fastened bolts due to thermal deformation of resin members. In order to prevent the above-mentioned problems, various products including resin members employ collars in a bolt fastening structure. 
     SUMMARY OF THE INVENTION 
     However, since a conventional shift lever apparatus employing collars is connected to a cable bracket with a resin housing by means of two bolts, it is necessary to insert two collars to the bolts, respectively. Accordingly, this arrangement complicates an assembly process of the shift lever apparatus. Further, due to a cylindrical shape of the collars, there is a limitation of lowering a production cost of such collars. Furthermore, it is necessary to provide various sizes of collars in order to adapt to various sizes of bolts. 
     It is therefore an:object of the present invention to provide an improved fastening structure which enables stable and rigid fastening between a resin member and a metal member by means of a bolt while enabling the decrease of the production cost thereof. 
     An aspect of the present invention resides in a fastening structure using a bolt which structure comprises a fastened member and a fastening seat inserted to the fastened member. The fastened member has a bolt hole for inserting the bolt and a pair of slits disposed around the bolt hole. The fastening seat has a pair of leg portions and a connecting portion integrally connecting the leg portions. The leg portions have a length which is substantially as same as a depth dimension of the bolt hole of the fastened member. The leg portions being inserted to the slits, respectively. 
     Another aspect of the present invention resides in a fastening structure using a bolt comprising: a fastening seat having a pair of leg portions and a connecting portion integrally connecting the leg portions, the leg portions perpendicularly extending from the connecting portions; and a fastened member having a bolt hole and a seat receiving hollow having a hollow shape corresponding to that of said fastening seat, the seat receiving hollow being fitted with the fastening seat. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view showing a shift lever apparatus employing a fastening structure according to the present invention. 
     FIG. 2 is a cross-sectional view showing an essential part of a bracket installation portion of the fastening structure of a first embodiment according to the present invention. 
     FIG. 3 is a cross-sectional view taken in the direction of allows substantially along the lines III—III of FIG.  2 . 
     FIG. 4 is a cross-sectional view taken in the direction of allows substantially along the lines IV—IV of FIG.  2 . 
     FIG. 5 is a cross-sectional view taken in the direction of allows substantially along the lines V—V of FIG.  2 . 
     FIG. 6 is a cross-sectional view taken in the direction of allows substantially along the lines VI—VI of FIG.  2 . 
     FIG. 7A is a plan view of a fastening seat employed in the fastening structure of the first embodiment according to the present invention. 
     FIG. 7B is a front view of the fastening seat of FIG.  7 A. 
     FIG. 7C is a side view of the fastening seat of FIG.  7 A. 
     FIG. 8 is an exploded perspective view showing the bolt fastening structure of the first embodiment. 
     FIG. 9 is a cross-sectional view showing the fastened state of the bolt fastening structure of FIG.  8 . 
     FIG. 10 is an exploded perspective view showing a second embodiment of the bolt fastening structure applied to the fastening of a housing to a vehicle body in accordance with the present invention. 
     FIG. 11 is a cross-sectional view taken in the direction of arrows substantially along the line XI—XI of FIG.  10 . 
     FIG. 12 is a cross-sectional view taken in the direction of arrows substantially along the line XII—XII of FIG.  10 . 
     FIG. 13A is a plan view showing the fastening seat employed in the second embodiment. 
     FIG. 13B is a front view showing the fastening seat of FIG.  13 A. 
     FIG. 13C is a side view showing the fastening seat of FIG.  13 A. 
     FIG. 13D is another side view showing the fastening seat of FIG.  13 A. 
     FIG. 14A is a plan view showing a modification of the fastening seat employed in the second embodiment. 
     FIG. 14B is a front view showing the fastening seat of FIG.  14 A. 
     FIG. 14C is a side view showing the fastening seat of FIG.  14 A. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 to  9 , there is shown a first embodiment of a bolt fastening structure according to the present invention. 
     As shown in FIG. 1, a shift lever apparatus  1  comprises a housing  6  made of plastic resin and a shift lever  11  swingably supported to the housing  6 . The housing  6  has a bracket installation portion  2  to which a cable bracket  3  is fixed by means of a pair of bolts  4 . The cable bracket  3  is made of metal plate and supports a shift cable  12  through an outer cover  12   a  of the shift cable  12 . The cable bracket  3  has two threaded holes  3   a  to which the bolts  4  are screwed. An end of the shift cable  12  is connected to a lower-end of the shift lever  11 , and the other end of the shift cable  12  is connected to an automatic transmission (not shown). 
     The bolts  4  are screwed through a fastening seat  5  and washers  8  and  9  to the threaded holes  3   a , respectively, to fixedly connect the bracket installation portion  2  of the housing  6  and the cable bracket  3 . An outer surface of the bracket installation portion  2  is a plate-like surface. It will be understood that washer faced bolts may be employed instead of the bolts  4  and the washers  8  and  9 . 
     The bracket installation portion  2  has a chamber  2   a , a circular hole  2   c , a slotted hole  2   d and two pairs of slits  2   e . The chamber  2   a  is defined by opposite two walls  2   b  and receives the cable bracket  3  therein. The circular hole  2   c  and the slotted hole  2   d  are aligned on an imaginary line IL which is slightly inclined from a horizontal plane HP as shown FIG.  2 . The two pairs of the slits  2   e  are formed in one of the walls  2   b  in parallel so as to locate the two holes  2   c  and  2   d  therebetween, as shown in FIG.  2 . More specifically, the slits  2   e  of each pair are arranged in parallel, and these two pairs are aligned side by side while inclining with respect to the imaginary horizontal plane HP, as shown in FIG.  2 . 
     Thick portions  2   f  are protrudingly formed around the holes  2   c  and  2   d  of the one of the walls  2   b , as shown in FIG.  8 . Each of the thick portions  2   f  is constituted by a cylindrical portion and a parallel two bars which are continuous with each other as is clearly shown in FIG.  8 . Top surfaces of the thick portions  2   f  protrude from a surface of the wall  2   b . A pair of straight thick portions  2   g  are formed in parallel with each other so as to locate the holes  2   c  and  2   d  therebetween as shown in FIG.  8 . The straight thick portions  2   g  also protrude from the surface of the wall  2   b , and the height level of top surfaces of the straight thick portions  2   g  generally corresponds to that of the top surfaces of the thick portions  2   f . That is, the top surfaces of the straight thick portions  2   g  and the top surfaces of the thick portions  2   f  are set to be generally in a plane. 
     Two washers  8  are fittingly installed on the straight thick portions  29  when the bolts  4  are installed to the holes  2   c  and  2   d . The thick portions  2   f  and  2   g  are provided in order to ensure a depth dimension of the holes  2   c  and  2   d  and to decrease unstableness of the fastening seat  5  thereon by increasing a contact surface between inner wall portions of the slits  2   e  and the fastening seat  5 . If the depth dimension of the slits  2   e  is greater than a predetermined dimension without these thick portions  2   f  and  2   g , it is not necessary to form these thick portions  2   f  and  2   g . 
     The fastening seat  5  comprises two pairs of leg portions  5   b  and a connecting portion  5   a  integrally connecting the two pairs of the leg portions  5   b . The connecting portion  5   a  is formed into an H-shaped plate as shown in FIG.  7 A. The leg portions  5   b  are in the form of a rectangular plate, respectively and are connected to four end portions of the H-shaped connecting portion  5   a . The two pairs of the leg portions  5   b  are arranged so that each pair of the leg portions  5   b  are aligned parallel. Each leg portion  5   b  has a U-shaped cutout portion  5   c  in the vicinity of the connecting portion  5   a , as shown in FIG.  7 B. The height dimension H of the leg portions  5   b  is set generally equal to the sum of the thickness of the wall  2   b  and the height dimension of the thick portions  2   f , and the height dimension H 1  of the connecting portion  5  is set to be smaller than the height dimension H of the leg portion  5   b  as shown in FIG.  7 B. 
     As shown in FIGS. 7A to  8 , the fastening seat  5  is inserted to the slits  2   e  so that opposing inner surfaces of each pair of the opposing leg portions  5   b  are press-fittingly in contact with opposing inner surfaces of the opposing slits  2   e  of each pair. End surfaces of the leg portions  5   b  inserted to the slits  2   e  are in contact with a surface of the cable bracket  3 . The other end surfaces of the leg portions  5   b , which are located at a side connected to the connecting portion  5   a , are leveled at a height generally the same as that of the thick portions  2   f  and  2   g . The bolts  4  are inserted to the circular hole  2   c  and the slotted hole  2   d , respectively, through the washers  8  and spring washers  9  and are screwed to the threaded holes  3   a  of the cable bracket  3 , respectively. By this screw connection between the bolts  5  and the threaded holes  3   a , the housing  6  and the cable bracket  3  are fixedly fastened with each other. 
     The fastening force of the bolts  4  is applied to the cable bracket  3  through the fastening seat  5 , and therefore even if the housing  6  made of plastic resin is repeatedly deformed by thermal change, the bolts  4  are never loosened from the fixedly fastened state. Therefore, the cable bracket  3  is fixedly connected to the housing  6  without generating looseness therebetween. 
     When the holes  2   c  and  2   d  are located adjacently with each other as mentioned in this embodiment, it becomes possible to made the fastening seat  5  into one piece as mentioned in this embodiment. This enables the number of parts to be decreased. 
     Since the fastening seat  5  is formed by bending a blanked flat metal plate, it is easily machined by means of press forming. This decreases the production cost of the product employing this fastening seat  5 . Further, since the leg portions  5   b  of the fastening seat  5  are formed in parallel, it is possible to adapt the fastening seat  5  to a case having different holes in diameter. This promotes common use of the fastening seat  5  to various bolts. 
     Furthermore, since the pair of slits  2   e  are formed in the housing  6  so as to locate the holes  2   c  and  2   d  for bolts  4  therebetween, it is possible to increase the connecting portion of the peripheral portions of the holes  2   c  and  2   d  to other portions of the housing  6 . This functions to increase a structural strength. Additionally, the connecting portion  5   a  for connecting the two pairs of the leg portions  5   b  is installed on a depressed portion  2   h  while pressing this depressed portion  2   h  and is formed large in size. Therefore, it is possible to ensure the supporting strength between the housing  6  and the cable bracket  3 . 
     Referring to FIGS. 10 to  13 D, there is shown a second embodiment of the fastening structure according to the present invention. The second embodiment discloses a fastening structure of the housing  6  to a vehicle body. 
     As shown in FIG. 10, the housing  6  for the shift selector lever comprises a flat installation portion  61  fixed to the vehicle body. The flat installation portion  61  has four fastening holes  62  at corner portions near four corners thereof. A reinforcement flange  61   a  is formed around each of the fastening holes (bolt holes)  62  at a lower surface of the flat installation portion  61  as shown in FIG.  11 . The reinforcement flange  61   a  is formed into a rectangular (grid) shape as viewed from a bolt installation direction. Each bolt  41  is inserted to each fastening hole  62  through a washer  8  and a spring washer  9  and screwed to a nut  72  fixed to a supporting portion  70  of the vehicle body. The supporting portion  70  has four holes  71  corresponding to the fastening holes  62 , and the four nuts  62  are fixed around the holes  71  so as to be screwed with the bolts  41 , respectively. By this screw connection between the bolts  4  and nuts  71 , the housing  6  is fixedly fastened to the vehicle body. 
     As is clearly shown in FIG. 10, a pair of slits  63  are formed in the installation portion  61  so as to locate each fastening hole  62  therebetween while being in parallel. The fastening holes  62  and the slits  63  are formed to have a depth dimension as same as that of the flange  61   a . A depressed portion  64  is formed at a portion near the fastening hole  62  as shown in FIG.  12 . 
     A fastening seat  51  is formed into a channel-shape in a plan view and has a pair of leg portions  52  and a connecting portion  53  through which the leg portions  52  are integrally connected. The leg portions  52  are inserted to the slits  63 , respectively. The height dimension H of the leg portions  52  is set generally equal to the depth dimension of the slit  63  and the fastening hole  62 . The depressed portion  64  is formed on the installation portion  61  so as to be lower in height level than the upper surface of the installation portion  61  by a thickness of the connecting portion  53 . The connecting portion  53  is engagedly fitted to the depressed portion  61 . 
     Since the fastening force of each bolt  41  is applied to the vehicle body installation plate  61  through each fastening seat  51  and even if the housing  6  made of plastic resin is repeatedly deformed by thermal change, each bolt  41  is never loosened from the fixedly fastened state. Therefore, the housing  6  is fixedly connected to the vehicle body installation plate  61  without generating looseness therebetween. 
     Since the leg portions  52  of the fastening seat  5  are formed in parallel, it is possible to adapt the fastening seat  5  to a case having different holes in diameter. This promotes common use of the fastening seat as a common part. 
     Furthermore, since the pair of slits  63  are formed in the installation portion  61  so as to locate the fastening hole  62  therebetween, it is possible to increase the connecting portion of the peripheral portions of the hole  62  to other portions of the housing  6 . This functions to increase a structural strength. Additionally, the connecting portion  53  for connecting the two pairs of the leg portions  52  is installed on the depressed portion  64  while pressing this depressed portion  64  and is formed large in size. Therefore, it is possible to ensure the supporting strength between the housing  6  and the vehicle body. 
     FIGS. 14A to  14 C show a modification of the second embodiment according to the present invention. 
     The modified fastening seat  51   a  comprises a pair of leg portions  52  and a pair of connecting portions  53  which connects both end portions of one of the leg portions  52  to both end portions of the other, as shown in FIG.  14 A. 
     Since the connecting portions  53  are engaged with a pair of depressed portions  64  arranged at both sides of the fastening hole  62  so as to press the depressed portions  64 , it is possible to increase an area for pressing the housing  6 . This functions to increase a structural strength between the housing  6  and the vehicle body. It will be understood that this modified fastening seat  51   a  is preferably applied to a bolt fastening structure where each bolt is located apart. 
     The contents of Application No. H11-136513 with a filing date May 19, 1999 in Japan are hereby incorporated by reference. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiment described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in the light of the above teachings. The scope of the invention is defined with reference to the following claims.