Abstract:
A reinforcing assembly for use with roll bars adapted to be mounted to motor vehicles such as an automobile. The reinforcing assembly includes a heat-expandable synthetic resin reinforcing member and a retainer configured to attach the member to the interior of a two-piece telescopically interfitting tubular roll bar construction. Upon heating, the reinforcing member expands to form a seal between the two roll bar tube sections thereby providing sound-reduction and stability of the roll bar assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a reinforcing member for interfitting channels. In particular, the invention relates to a heat-expandable reinforcing assembly that creates a seal between two tube sections of a motor vehicle roll bar for noise reduction and reinforcement of the joint between the tube sections. 
     2. Description of the Prior Art 
     Roll bars, commonly used on motor vehicles to prevent injury to the motor vehicle operator in the event the vehicle is overturned, generally include a welded tubular construction alone or in combination with a two-piece telescopically interfitted tubular construction wherein the two pieces are held together by means of a bolt or similar fastening means. In use, the fastener may become loose or may fall out of the roll bar assembly causing the two roll bar sections to bang against one another thereby creating an annoyance to the motor vehicle operator and, more importantly, creating a hazard in that the noise of the two sections rattling against one another may prevent the motor vehicle operator from hearing emergency vehicles, car horns, or other auditory warning signals. Accordingly, there is an unsolved need in the state of art for a roll bar reinforcing assembly that provides stabilization of the roll bar sections, reduces noise associated with the banging together of the roll bar sections, and is easy and economical to install from both a labor and material standpoint. 
     SUMMARY OF THE INVENTION 
     The present invention solves the prior art problems discussed above and provides a distinct advance in the state of the art. In particular, the reinforcing member hereof enables reinforcement of a two piece roll bar for a motor vehicle thereby providing sound reduction as well as advantageously enabling finishing liquids such as anti-rust coatings to penetrate and flow through the inside of the roll bar. 
     The preferred embodiment includes a tubular construction comprising a pair of separate, telescopically interfitted tubular components that cooperatively present a joint therebetween as well as a reinforcing assembly that is operatively located within the interfitted components and proximal the joint. The reinforcing assembly includes a body of heat-expandable synthetic resin material that increases in volume upon heating in order to provide a seal adjacent the joint. When heated, the body engages the tubular components thereby providing a sound-reducing seal which bonds together with metal components and adds strength in the area of the expanded resin material. 
     The preferred reinforcing assembly is adapted to be located within a pair of telescopically interfitted tubular components in order to join and seal the joint therebetween. The preferred reinforcing assembly comprises a body of heat-expandable synthetic resin material configured for location within the tubular components adjacent the joint and a retainer coupled with the body in order to position the body within the tubular components prior to heat expansion of the body. The retainer serves to locate the synthetic resin material in proximately to the joint and preferably maintains the resin in a desired, axially centered position prior to expansion. Alternatively, the synthetic resin of the reinforcing assembly may be shaped by molding or the like into a complemental shape for receipt within the tubular construction adjacent the joint so that the two tubular components serve to aid in locating the material for expansion at the joint. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the two-piece tubular construction of the present invention showing the inner tube section in phantom lines; 
     FIG. 2 is top plan view of the tubular construction of FIG. 1 taken along line  2 — 2 ; 
     FIG. 3 is a side elevational view of the tubular construction of FIG. 1 taken along line  3 — 3  showing the reinforcing assembly and cross connector assembly prior to heat expansion in cross-section; 
     FIG. 4 is a side elevational view in cross-section showing the reinforcing assembly and cross connector after heat expansion; 
     FIG. 5 is a side elevational view of the reinforcing assembly in partial cross-section; 
     FIG. 6 is a side elevational view in cross-section showing the second preferred reinforcing assembly prior to heat expansion; 
     FIG. 7 is a side elevational view of the reinforcing assembly of FIG. 6 in partial cross-section; 
     FIG. 8 is a top plan view of the reinforcing assembly of FIG. 7; 
     FIG. 9 is a bottom plan view of the reinforcing assembly of FIG. 7; 
     FIG. 10 is a side elevational view in cross-section of a third embodiment of the preferred reinforcing assembly prior to heat expansion with the upper tube section removed for clarity; 
     FIG. 11 is a top plan view of the reinforcing assembly of FIG. 10; 
     FIG. 12 is a side elevational view in cross-section of a fourth embodiment of the preferred reinforcing assembly prior to heat expansion with the upper tube section removed for clarity; 
     FIG. 13 is a top plan view of the reinforcing assembly of FIG. 12; 
     FIG. 14 is a side elevational view in cross-section of a fifth embodiment of the preferred reinforcing assembly prior to heat expansion; 
     FIG. 15 is a side elevational view of the reinforcing assembly of FIG.  14 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, FIG. 1 illustrates a preferred roll bar connection assembly  10  in accordance with the present invention. Broadly, roll bar is made up of two elongated, interfitted tubes which cooperatively define a generally U-shaped roll bar attached to a vehicle such as an automobile. The assembly  10  is between the ends of the overall roll bar, and includes a first tube section  12 , a second tube section  14 , a cross connector assembly  16  and a reinforcing assembly  18  which is normally hidden from view. In more detail, the second tube section  14  presents a reduced diameter section  19  that telescopically interfits within the larger first tube section  12 . First tube section  12  includes a sidewall  20  having an inner face  22 , an outer face  24 , and an aperture  26  extending through sidewall  20  from inner face  22  to outer face  24 . Second tube section  14  likewise includes a sidewall  28  having diametrically opposed holes  29  therethrough, an inner face  30 , an outer face  32 , and an internal end section  34 , the sidewall  28  surrounding a through bore  33 . 
     Cross connector assembly  16  includes a bolt  36  having an enlarged head  36 A and a threaded shank  36 B and an internally threaded sleeve  38  configured to receive the shank  36 B of bolt  36  therein. Sleeve  38  is received within bore  33  and secured to sidewall  28  so that sleeve  38  extends transversely across the interior of sidewall  28  and is positioned in registry with aperture  26 . 
     Reinforcing assembly  18  includes a reinforcing member  40  formed of heat-expandable synthetic resin material and a retainer  42 . Reinforcing member  40  is generally disc-shaped prior to expansion and includes first face  44 , opposed second face  46  and circumferential rim  48 . The reinforcing member  40  thus presents a height between the first face  44  and the second face  46  in an unexpanded condition as shown in FIGS. 3 and 5 of about preferably 4 to 8 cm to a typical roll bar construction, although this amount will vary depending on the particular application and size of the tube sections. Reinforcing member  40  further includes a central perforation  50  as well as grooves  52  formed about the rim  48  of member  40  and extending between first and second faces,  44  and  46 . The member  40  thus presents a scalloped edge configuration. In addition, the reinforcing member  40  includes a narrowed neck  49  of a reduced diameter relative to rim  48  and which projects below end margin  34  and partially extends into tube section  14  to aid in locating the reinforcing member  40  as shown in FIG.  3 . 
     One particularly preferred composition for use as member  40  is commercialized under the name SIKAREINFORCER (Sika Corporation, Madison Heights, Mich.). In more detail, the most preferred material for use in reinforcing member  40  comprises: from about 20-30% by weight of a styrene-butadiene-styrene (SBS) block co-polymer (e.g., Fina Clear 530®); from about 5-20% by weight of a polystyrene (e.g., Fina Crystal 500® and Fina Crystal 535®); from about 30-45% by weight of a bisphenol A-based liquid epoxy resin (e.g. Araldite 6010® and Epon 71®); from about 0.5-5% by weight of a pigment such as carbon black; up to about 5% by weight butadiene acrylonitrile rubber (Nipol 1411); from about 1-10% by weight hydrated amorphous silica (HiSil 233); from about 10-20% by weight glass microspheres (Scotchlite S60); from about 0.1-5% by weight of a blowing agent such as azodicarbonamide (e.g., Celogen AZ 765®, Celogen AZ 754A®, and Celogen AZ 130®); from about 0.1-5% by weight of a catalyst such as N, N, dimethyl phenyl urea (U405); from about 0.1-5% by weight of a curing agent such as sulfur or dicyandiamide (DDA10); and up to about 5% by weight of a “kicker” such as zinc oxide to lower the blowing temperature, with all percents by weight being based upon the total weight of the material taken as 100% by weight. 
     A particularly preferred composition of the member  40  comprises about 12.94% polystyrene, about 23.22% SBS block copolymer, about 0.57% carbon black, about 1.90% butadiene acrylonitrile rubber, about 4.28% hydrated amorphous silica, about 38.07% bisphenol A-based liquid epoxy resin, about 14.75% glass microspheres, about 0.46% zinc oxide, about 2.85% dicyandiamide, about 0.38% N,N dimethyl phenyl urea, and about 0.57% azodicarbonamide. In certain applications where increased compressive strength and reduced foaming and expansion is desired, the foregoing may be adjusted such that the polystyrene is reduced to about 12.63%, the SBS block copolymer is reduced to about 22.59%, and the butadiene acrylonitrile rubber is increased to about 2.85%. 
     The member  40  can be formed by mixing the SBS block co-polymer with a small portion (about {fraction (1/40)}th of the total amount) of the bisphenol A-based liquid epoxy resin in a heated mixer until the temperature of the mixer reaches from about 240-260° F. (the temperature of the mixture within the mixer is at least about 175° F.), and the mixture is substantially homogeneous, at which time the polystyrene is added to the mixer and mixing is continued. After the polystyrene is substantially mixed with the SBS block co-polymer/epoxy resin mixture, the remainder of the bisphenol A-based epoxy resin is slowly added to the mixer, stopping and starting the mixer as necessary, with the ingredients being thoroughly mixed to obtain a substantially homogeneous mixture. The desired amount of this mixture is placed in a heated mixer (set at a temperature of about 250° F.) and mixing is commenced. While mixing, the carbon black and rubber are added to the mixer and mixing is stopped once a homogeneous mixture is obtained within the mixer. Either the silica or glass microspheres is added to the mixer, and mixing is resumed and continued until the mixture is homogeneous. This step is repeated, adding the other of the silica or glass microspheres. 
     The temperature of the mixer is then set to a temperature below 160° F., the blowing agent(s), catalyst(s), kicker, and curing agent(s) are added, and mixing is resumed and continued only until the mixture is homogeneous. The resulting mixture is then preferably extruded into strands (at an extruder temperature of 170-180° F. and screw rotation speeds of about 400 rpm) and cut into pellets. The pellets are then injection molded at a temperature of about 180-200° F. using injection molding equipment designed to form the desired shape of the member  40  to be attached to the retainer  42  or otherwise molded into a configuration for positioning adjacent the joint  43  between the first tube section  12  and second tube section  14 . 
     Retainer  42  includes an attachment member  54 , a first leg  56  and a second leg  58 . Attachment member  54  has a standard  60 , a series of aligned skirts  62 , and base  64  as shown in section in FIGS. 4 and 5. Skirts  62  are integral with standard  60  and project outwardly therefrom in axially-spaced alignment. Standard  60  projects from base  64 . Attachment member  54  extends through first face  44  into perforation  50  so that base  64  contacts first face  44  and the tip of standard  60  is generally flush with second face  46 . Legs  56  and  58  project outwardly from base  64  in a generally opposite direction from standard  60  and resiliently receive sleeve  38  for locking engagement of reinforcing assembly  18  with sleeve  38 . 
     In use, the reinforcing assembly  18  is positioned adjacent the internal end margin  34  of the second tube section  14  prior to intermitting of the first tube section  12  and second tube section  14 . The retainer  42  is preferably coupled to the sleeve  38  as shown in FIG.  3 . The circumferential rim  48  serves to locate the reinforcing member  40  in a substantially axially centered position. The retainer  42  serves to maintain the reinforcing assembly  18  in proper position notwithstanding movement or tumbling of the roll bar connection assembly  10 . The bolt  36  is tightened against the sidewall  20  of the first tube section  12 . The axially oriented, circumferentially spaced groves  52  and the gap between the circumferential rim  48  and the interface  22  of the first tube section  12  help to ensure that any rust protecting composition received within the first tube section  12  is permitted to drain past the reinforcing member  40  and thoroughly coat the assembly  10 . When the vehicle to which the roll bar assembly  10  is secured is painted, it is typically passed to a bake oven. Upon heating of the roll bar connection assembly  10  in a bake oven to a temperature of at least 300° F., and preferably about 325° F. for a period of about 10 minutes, the reinforcing member  40  will activate, to melt, foam and expand. The base  64  aids in directing the expanding reinforcing member  40  and resisting excessive sag thereof during melting. The resulting reinforced roll bar connection assembly  10  is then allowed to cool to ambient temperature. 
     In another preferred embodiment of the reinforcing assembly  18   a  illustrated in FIGS. 6-9, wherein like parts are numbered in the same manner as the embodiment shown in FIGS. 1-5, a two-piece retainer  42   a  is depicted which includes attachment member  54   a  seated within a cup-shaped stepped bore  65  with a central opening in the base of member  40 , a first leg  56 , a second leg  58  and a projecting tubular shank  66 . Attachment member  54   a  is formed of synthetic resin material such as nylon having a higher melting point than that used in the material of member  40  and includes a first arm  68 , a second arm  70 , a post  72 , and a fastener  74  formed on the end of post  72  and configured to lockingly engage post  72  and shank  66 . Arms  68  and  70  project outwardly from post  72  which extends through bore  65  until the tops of arms  68  and  70  are generally flush with second face  46 . Post  72  snap-fits within shank  66  and fastener  74  lockingly engages shaft  66  to prevent longitudinal shifting of post  72  relative to shank  66 . However, post  72  is permitted to swivel within the shank  66 , thus permitted relative rotational movement of the reinforcing member  40  relative to retainer  42   a  relative to the attachment member  54   a . Legs  56  and  58  project outwardly from shank  66  in a generally opposite direction from arms  68  and  70  and resiliently receive sleeve  38  for securing coupling the reinforcing assembly  18  to the sleeve  38 . By permitting the reinforcing member  40  to rotate relative to the sleeve  38 , alignment and installation of the reinforcing assembly  18  is greatly facilitated. 
     A third preferred embodiment of the reinforcing assembly  18   b  is shown in FIGS. 10 and 11 which is of a simplified two-piece construction for use with the roll bar connection assembly  10 . In this embodiment, reinforcing member  40   b  presents two apertures  76  and  78  that extend through member  40   b  from first face  44  to second face  46 . Second face  46  includes a depression  80  extending between the apertures  76  and  78  and configured to receive attachment member  81 . Attachment member  81  includes a formed wire bight  82 , first leg  84 , and a second leg  86 . Attachment member  81  couples with second face  46  of reinforcing member  40   b  by inserting leg  84  into first aperture  76  and inserting second leg  86  into second aperture  78  in such a manner that legs  84  and  86  extend through reinforcing member  40   b  and project outwardly from first face  44 . Depression  80  therefore receives bight  82  in locking engagement. Legs  84  and  86  each include an arcuate section  88 ,  90  configured to receive sleeve  38  for locking engagement of reinforcing assembly  18   b  with sleeve  38 . 
     FIGS. 12 and 13 illustrate a fourth preferred embodiment of the reinforcing member  18   c  similar to that of FIGS. 10 and 11 except that the attachment member  92  presents legs  94  and  96  which are generally arcuate and configured to engage the inner face  30  of sidewall  28 . Thus, the legs  94  and  96  of the reinforcing member  18   c  serve to frictionally engage the inner face  30  of the second tube section  14  but do not normally engage the sleeve  38  except when the member  40  moves longitudinally away therefrom. 
     Finally, in another preferred embodiment, as shown in FIGS. 14 and 15, reinforcing member  40  is molded into a configuration complemental to the second, inner tube section  14  whereby the member  40   c  includes an enlarged upper body  98  sized to rest upon the end margin  34  of the second tube section  14  and a narrowed neck  100  configured for insertion into the bore  33 . The complemental and interfitting relationship between the member  40   c  and the second tube section  14  permits the bulk of the thermally expandable reinforcing material of the body  98  of member  40   c  to flow into the joint for receipt both above and below the margin  34  and in the space between the reduced diameter section  19  and the interface  22  of the first tube section  12 . In addition, if desired, the reinforcing member  40   c  may be temporarily coupled with internal end section  34  of tube section  14  by affixing first face  44  to the margin  34  with glue or the like, or the first face  44  may be provided with a transversely or diametrically extending groove complemental to the outer surface of sleeve  38  whereby the reinforcing member may be supported on the sleeve  38 . 
     In use, reinforcing assembly  18  is coupled with sleeve  38  within second tube section  14 . Second tube section  14  is telescopically interfitted with first tube section  12  and secured in place by inserting bolt  36  into sleeve  38  thereby forming a generally U-shaped roll bar which is then coupled to a motor vehicle. The motor vehicle may be sprayed or dipped with an anti-rust solution, paint, or any other finishing solution. The liquid flows through tube sections  12  and  14  past reinforcing assembly  18  by way of grooves  52  on reinforcing member  40  and past the gap between the rim  48  and the inner face  22  of the sidewall  20  of the first tube section  12 , thereby thoroughly coating inner faces  22  and  30  of sidewalls  20  and  28 . The motor vehicle is then baked at a predetermined temperature sufficient to allow curing of the liquid thereby resulting in the expansion of reinforcing member  40  so that a seal is formed between tube sections  12  and  14  as shown in FIG.  3 . The resulting expanded material of the member  40  bonds to the sleeve  38  as well as to the tubes  12  and  14 , thus creating not only a substantially reinforced connection between the first and second tube sections, but also creates a seal which provides significant sound-reducing capabilities and prevents rattling of tube sections  12  and  14  against one another in the event bolt  36  becomes loose or is freed from sleeve  38  during operation of the motor vehicle. As may be seen in FIG. 4, during expansion of the material of the reinforcing member  40 , the material flows into the junction between the tubes  12  and  14  to provide a strong, rigid, sealing connection. 
     Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is by way of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of their invention as pertains to any apparatus or method not materially departing from but outside the literal scope of the invention as set out in the following claims.