Abstract:
A tow bar for connecting a vehicle to an object to be towed which reduces impact related structural damage to the vehicle. The tow bar is positioned within the vehicle bumper wherein the bumper contains a section for concealing the tow bar and wherein the tow bar positioned within the bumper, when in a non-towing mode, is movable relative to the bumper, and wherein the tow bar can also be configured into a non-slidable towing configuration.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a bumper tow bar system for an automobile which reduces impact related structural damage to the vehicle. 
     BACKGROUND OF THE INVENTION 
     Currently, vehicles having built-in towing capability rely on a system utilizing a solid metallic connection between the ball/tow bar and the vehicle frame. Towing systems according to this design provide a secure and rigid towing arrangement, but have very poor impact protection characteristics. When an impact occurs at the ball/tow bar, i.e. a rear impact, the energy of the impact is transmitted through the rigidly connected ball/tow bar to structural components of the vehicle. Even relatively minor rear impacts may result in distortion of the vehicle frame, producing damage that is very costly to repair. 
     Furthermore, while there are not currently any impact standard requirements for SUV&#39;s, trucks, and vans that correspond to the 5 mph impact standard for passenger cars, it is anticipated that in the near future such safety standards will be instituted. In fact, many original equipment manufacturers are already asking for product designs for built in tow packages that will satisfy low speed impact safety standards, such as the 5 mph impact standard. However, while 5 mph bumpers have been available on passenger cars for some time, such bumpers have not been applicable to vehicles having built-in tow packages. Regardless of the impact characteristics of the bumper, the rigidly fixed ball/tow bar will still continue to transmit energy directly to the frame of the vehicle. 
     With regards to specific prior art disclosures directed at tow bars in general, attention is directed to the following U.S. Pat. Nos. 3,787,910; 3,972,544; 4,025,010, 4,186,938; 4,194,755; 4,405,148; 4,577,883; 4,666,359; 5,071,153; 5,147,095; 5,429,382; 5,845,922. 
     What is therefore desired is a towing system that does not transmit energy from an impact directly to the frame of the vehicle. Furthermore, it is desired to have a towing system that allows the application of current impact absorbing bumpers, as known in the art, to vehicles equipped with such towing systems. 
     SUMMARY OF THE INVENTION 
     A tow bar for connecting a vehicle to an object to be towed wherein said tow bar is positioned within a vehicle bumper, wherein said bumper contains a section for positioning said tow bar within said bumper and wherein said tow bar positioned within said bumper, when in a non-towing mode, is movable relative to said bumper, and wherein said tow bar can also be configured into a non-slidable towing configuration. 
     In corresponding embodiment, the present invention relates to a towing system for a vehicle comprising a structural member secured to said vehicle, a bumper disposed adjacent to said structural member, a tow bar disposed within said bumper and slidable within said structural member, said tow bar having a first stop preventing sliding removal from said structural member in the direction of said bumper, and a second stop releasably preventing sliding movement of said tow bar in the direction of said structural member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are set forth in the following description as shown in the drawings, wherein: 
     FIG. 1 illustrates in cross-sectional view an exemplary embodiment consistent with the present invention configured in impact energy management condition; 
     FIG. 2 illustrates in cross-sectional view and exemplary embodiment consistent with the present invention at impact energy management; 
     FIG. 3 illustrates in cross-sectional view an exemplary embodiment consistent with the present invention configured in towing condition. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the figures, an exemplary embodiment of the sliding, tow bar bumper system consistent with the present invention is shown at  10 . The bumper system generally comprises a bumper  12  supported by a structural cross bar  14 , therebehind. A tow bar  16  is slidably disposed in the structural cross bar  14 , and housed within the bumper  12 . 
     FIG. 1 illustrates the exemplary bumper system  10  in impact energy management condition. The bumper  12  is preferably a molded plastic member, more preferably a molded plastic member having a cosmetic outer surface  18 . The bumper  12  may be of the conventional type designed to provide low speed, e.g. 5 mph, impact energy management. The low speed impact energy management characteristics may be improved by an energy absorbing foam or other energy absorbing features disposed on the interior  20  of bumper  12 . As shown in FIG. 1, bumper  12  preferably also includes an outward extension  22  providing mounting clearance for a hitch ball. The bumper system  10  also comprises a structural, preferably metallic, cross bar  14 . Cross bar  14  is preferably configured as a box beam, although it may alternately be formed as a channel member, a plurality of brackets, etc. The cross bar  14  is preferably disposed transverse to the axis of the vehicle and is secured to vehicle structural members, therein providing the required strength to support and tow a trailer etc. 
     The cross bar  14  preferably further comprises a bumper attachment face  24  configured to secure the bumper  12  thereto. The bumper  14  may be attached to the cross bar using an adhesive, mechanical fasteners, or other attachment means known in the art. 
     The final component of the bumper system  10  is a tow bar  16 . The tow bar  16  may be housed within, and is preferably concealed by, the bumper  12 . The tow bar  16  is preferably an elongated member formed from a structural, preferably metallic, material having sufficient strength to support and tow a trailer etc. The tow bar  16  is coupled to the bumper  12  by a torque sleeve  26 . The torque sleeve  26  is a hollow cylindrical member disposed in the hitch ball mounting hole  28  of the tow bar  16 . The torque sleeve  26  extends through the hitch ball mounting hole  28  and is secured to the bumper  12 , therein coupling the tow bar  16  and the bumper  12  and allowing a hitch ball  46  to be rigidly mounted therethrough without unduly compressing or marring the bumper  12 . 
     The tow bar  16  extends through the bumper  12  and passes through cross bar  14 , being slidably retained therein. Slidable retention of tow bar  16  by cross bar  14  is preferably achieved by receiving the tow bar  16  in a passage  30  extending through the cross bar  14 . The passage  30  is preferably sized to slidably retain the tow bar  16  while simultaneously minimizing slop or play of the tow bar  16 . Minimization of slop or play of the tow bar  16  within the passage  30  may be enhanced by providing the passage  30  with support flanges  32  configured to ride on the tow bar  16 . 
     Pull-out of the tow bar  16  from the passage  30  is prevented by a stop pin  34  attached near the end of the tow bar  16 . The stop pin  34  is securely retained to the tow bar  16  by such means as welding, press fit, threaded engagement, etc. Alternately, the stop pin  34  may be replaced by a feature such as a flange on the end of the tow bar  16 , a localized thickening of the tow bar  16 , etc. The stop pin  34  is disposed on the back side of the cross bar  14 , relative to the bumper  12 , therein preventing pull out in the direction of the bumper  12  while still allowing sliding displacement in the opposite direction, i.e. in the direction of an impact force. 
     Pivotally extending from the stop pin  34  is a spring clip  36  formed from a length of resilient material. Disposed on the distal end of the spring clip  36  is a locking pin  38 . The length of the spring clip  36  and the dimensions of the locking pin  38  are configured to allow engagement of the locking pin  38  in a locking opening  40  disposed in the tow bar  16 , passing through a locking pin orifice  42  in the bumper  12 . The locking hole  40  is disposed on the opposite side of the cross bar  14  from the stop pin  34 . 
     FIG. 2 illustrates the exemplary bumper system  10 , consistent with the present invention, subsequent to an impact from the energy management configuration shown in FIG.  1 . When a bumper system consistent with the present invention receives an impact, e.g. from a low speed collision etc., the energy of the impact is absorbed and dissipated by the bumper  12  with minimal transmission of the impact forces to the structural components of the vehicle, thereby minimizing any damage to the frame or structure of the vehicle. As illustrated in FIG. 2, upon impact the tow bar  16  slides away from the impact through the opening  30  in the cross bar  14 . The sliding motion of the tow bar  16  allows the tow bar  16  to be displaced by the impact without transmitting a damaging amount of energy to the cross bar  14 , and therein to the structure of the vehicle. As will also be noted in FIG. 2, because the tow bar  16  is able to slide away from the impact, the bumper  12  is able to crumple and deform, therein absorbing the bulk of the energy from the impact. The energy absorbing characteristics of the bumper  12  may further be improved by incorporating an energy absorbing foam or energy absorbing features into the bumper  12 . 
     FIG. 3 illustrates the exemplary bumper system  10  configured for towing. During towing, in order to prevent the forward movement of the tow bar  16  during braking, or while traveling down an incline, the tow bar  16  must be locked in place. Consistent with the present invention, during towing the tow bar  16  may be locked against forward travel using the locking pin  38 . The locking pin  38  is engaged in the locking hole  40  by deflecting the spring clip  36  using the pull loop  52 , pivoting the spring clip  36  about the axis of the stop pin  34 , and engaging the locking pin  38  through orifice  42  in the bumper  12  and into the locking hole  40 . The locking pin  38  is retained in the locking hole  40  by the upward spring force of the spring clip  36 . 
     Towing may be accomplished using a standard hitch ball  46  installed in the hitch ball mounting hole  28 . The hitch ball  46  is secured in the hitch ball mounting hole  28  using a washer  48  and a nut  50 . Damage to the bumper  12  resulting from over tightening the nut  50  is prevented by the torque sleeve  26 . When the hitch ball  46  is installed, the rim  54  of the hitch ball  46  bears on the torque sleeve  26 , which is formed from a crush resistant material, preferably a metallic material. 
     Consistent with the above description, when the bumper system  10  is configured for towing as illustrated in FIG. 3, the bumper/towing system of the present invention provides a strong and secure towing assembly. The weight of the item to be towed is supported by the tow bar  16  which is in turn supported by the cross bar  14 , and therethrough by structural components of the vehicle. The stop pin  34  prevents the tow bar  16  from pulling out of the cross bar  14 , e.g. when accelerating or ascending an incline. In a similar manner the locking pin  38  prevents the tow bar  16  from sliding forward as during braking or descending an incline. Once towing is completed, the locking pin  38  is removed, and the bumper/towing system is returned to the energy management configuration illustrated in FIG.  1  and described above. 
     Although this invention has been disclosed and illustrated with reference to particular embodiments, the principles involved are susceptible for use in numerous other embodiments which will be apparent to persons of ordinary skill in the art. Accordingly, the invention is, therefore, to be limited only as indicated by the scope of the appended claims.