Integrated muffler-bumper system

A space efficient, structurally rigid, integrated muffler and bumper assembly is provided. The muffler and bumper assembly comprises an extruded skeleton, an energy absorbing bumper, and a bumper fascia. The extruded skeleton is formed such that internal cavities or passage flow chambers exist. In turn, the walls of the flow chambers maintain a plurality of holes, allowing for passage of exhaust gases between chambers. The extruded skeleton also has an inlet and outlet for exhaust gas flow. Arms having tabs on the ends thereof extend from the top and bottom of the extruded skeleton such that the energy absorbing bumper, which maintains recesses in the top and bottom portions, snap-fits with the extruded skeleton. The extruded skeleton/bumper assembly is welded or otherwise mechanically fastened to the vehicle frame rails. The bumper fascia is introduced over the extruded skeleton/bumper assembly generally masking the assembly with the overall vehicle design. Both the energy absorbing bumper and the bumper fascia have bores formed therein to receive the exhaust outlet of the extruded skeleton.

FIELD OF THE INVENTION
 The present invention relates generally to vehicle safety and exhaust
 systems and more particularly to an integrated assembly including a
 muffler system and extruded bumper retention system.
 BACKGROUND AND SUMMARY OF THE INVENTION
 It is a consistent drive of the automotive industry as a whole to reduce
 the overall complexity of motor vehicles. Original Equipment Manufacturers
 (OEM) and suppliers alike seek to reduce the total amount of parts that
 comprise a particular vehicle build which usually can exceed 5000. It is a
 further objective of OEM's to improve the overall vehicle packaging
 constraints so as to provide aperture with either more interior room or
 ground clearance. Consisting contemporaneously with these drives is the
 desire to improve consumer satisfaction and occupant safety.
 Some of these objectives can be met by enhancing the exhaust systems and
 collision of a vehicle. In particular, by integrating the muffler into the
 rear bumper system of a vehicle there is a reduction in the amount of
 parts needed for vehicle assembly which reduces production time. Vehicle
 packaging constraints are also improved by moving the muffler up away from
 the lower portion of the vehicle into the bumper region thereof.
 It is an object of a prior invention, U.S. Pat. No. 5,726,398, to achieve
 these objectives through integrating the muffler into the bumper system.
 However, the muffler components of the prior invention are those of a
 traditional method of producing mufflers housed within the bumper.
 Therefore, the muffler portion of the combined systems is more complex
 than need be. There continues to be a need in the art to provide a simple,
 cost effective, and compact way of providing a truly integrated bumper and
 exhaust system.
 It is an object of the present invention to achieve the objectives set by
 OEM's and sub-suppliers alike both by fully integrating the muffler into
 the bumper system as well as designing a simpler, longer lasting muffler
 system itself. This is achieved via an extruded skeleton acting as a
 muffler. The extrusion process used to form the skeleton creates gas
 exhaust flow channels along the length of the muffler. These gas exhaust
 channels incorporate exhaust passage holes for allowing the flow of
 exhaust gases between channels. Exhaust inlet and outlets are formed on
 opposing sides of the extruded skeleton which allow for exhaust gases to
 enter and exit the muffler respectively.
 Several advantages of the extruded skeleton formation are readily apparent.
 Initially, the near square form of the exhaust chambers allow for more
 efficient utilization of space reducing the overall size of the muffler,
 thus lowering packaging needs. Additionally, active or semi-active noise
 attenuation components can be easily integrated into the flow chambers of
 the extruded skeleton. Traditional muffler construction employs
 thin-walled sheet metal which is susceptible to fatigue and corrosion. The
 extruded skeleton, being formed as such, allows for greater wall
 thickness, improving the wearability and corrosion characteristics of the
 muffler. Finally, this method of producing the muffler system allows for a
 more rigid structure than that of traditional muffler systems. This added
 rigidity can be utilized in several ways including crash resistance and/or
 improving the rigidity of the overall frame structure as the skeleton can
 be attached directly to the frame members.
 Further areas of applicability of the present invention have become
 apparent from the detailed description provided hereinafter. It should be
 understood, however, that the detailed description and the specific
 examples, while indicating preferred embodiments of the invention, are
 intended for purposes of illustration only, since various changes and
 modifications within the spirit and scope of the invention will be
 apparent to those skilled in the art from the detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 With reference to FIG. 1, the extruded skeleton of the integrated muffler
 and bumper system will now be described. The extruded skeleton 10 is
 formed so as to have top and bottom walls 11a, side walls 11b and a
 plurality of internal walls 13, which form top and bottom walls 11a, side
 walls 11b and a plurality of internal walls 13, which form a plurality of
 internal cavities 12a-d. The internal cavities 12a-d act as exhaust gas
 flow chambers of the muffler and are near-square in shape. Portions of
 internal walls 13 maintain a plurality of holes 14 allowing for passage
 between the internal cavities 12a-12d of exhaust gases. With reference to
 FIG. 5, the center section 15 of the extruded skeleton is shown with the
 upper and lower cavities removed for clarity. The exhaust gases enter the
 center section 15 through the exhaust inlet port 16. The gases flow in the
 direction of arrow "A" to the opposite end of internal cavity 12a.The
 gases then flow through the upper and lower exhaust passage holes 14a and
 thereby enter the internal cavities 12b, 12c best shown in FIG. 1. The
 gases then flow in an opposite direction to arrow "A" along the internal
 cavities 12b, 12c and pass through upper and lower exhaust passage holes
 14b and enter the internal cavity 12d. The gases then follow the direction
 of arrow "C" along the internal cavity 12d and exit through the outlet
 port 18. Noise attenuation material 19 can also be introduced into
 internal cavities 12a-d, including active or semi-active. Exhaust gas
 inlet 16 is connected to a back face of the extruded skeleton and exhaust
 gas outlet 18 is connected to a front face of the extruded skeleton 10.
 Both the top and bottom walls 11a include an extended tab portion 21
 projecting therefrom in a cantilevered manner. It should now be noted that
 the tab portions 21 extend the full lateral length of the extruded
 skeleton 10. Located at the distal end of the tab portion 21 is a mounting
 rib 22. The mounting rib 22 also runs the full lateral length of the
 extruded skeleton 10.
 FIG. 2 displays a subassembly of an integrated bumper/muffler system. The
 subassembly 20 comprises the extruded skeleton 10, endplates 24, and an
 energy absorbing bumper 26. The end plates 24 can be mechanically or
 adhesively fastened to the skeleton 10. FIG. 3 displays a more detailed
 view for mounting the extruded skeleton 10 to the vehicle frame and
 mounting of the energy absorbing bumper 26 to the extruded skeleton 10,
 thus forming subassembly 20. The extruded skeleton 10 is welded directly
 to frame rails 30. The extruded skeleton 10, being formed as such, offers
 a rigid frame cross member when attached to frame rails 30. This offers
 the vehicle improved stiffness and rigidity or conversely removes the need
 for a rear vehicle cross member.
 The top and bottom surfaces of the energy absorbing bumper 26 have recessed
 grooves 23 integrally formed therein. The energy absorbing bumper 26 also
 has an exhaust portal 28 molded directly into it. The energy absorbing
 bumper 26 is then mounted to the extruded skeleton 10 via snap fit or
 slide fit means. The energy absorbing bumper 26 is pressed in between arms
 21 causing said arms to bend in an outward fashion until the mounting ribs
 22 reach the recessed groove 23 of the energy absorbing bumper 26. At this
 point, the arms 21 return and thereby form a secure connection between the
 bumper 26 and skeleton 10. Mounted as such, the exhaust gas portal 28 of
 energy absorbing bumper 26 services the passage of the exhaust gas outlet
 18 of the extruded skeleton. This allows exhaust gases to escape.
 An exhaust system thus formed would generally not blend with modern vehicle
 designs nor is it particularly catching to the eye. Therefore, such a
 system preferably includes an additional cover up cleaner to make it more
 aesthetically pleasing and form better into the overall vehicle design.
 With reference to FIG. 4, a side sectional view of a complete integrated
 muffler bumper assembly is depicted having such a covering. The assembly
 40 is comprised of subassembly 20 as described earlier, with the
 introduction of a bumper fascia 32. In order to mount the bumper fascia
 32, holding brackets 36 preferably are introduced. The holding brackets 36
 may be attached to the vehicle at any of several locations, including the
 extruded skeleton 10. In the preferred embodiment, the fascia 32 is
 screwably attached to holding brackets 36 via screws 34. As described
 earlier, the subassembly 20 is attached to the frame rails 30 such that
 the complete bumper assembly 40 is rigidly attached to the vehicle.
 The invention being thus described, it will be obvious that the same may be
 varied in many ways. Such variations are not to be regarded as a departure
 from the spirit and scope of the invention, and all such modifications as
 would be obvious to one skilled in the art are intended to be included
 within the scope of the following claims.