Patent Application
20090077956
The invention relates to exhaust systems for vehicles, in particular heavy trucks. More particularly, the invention relates to a flexible coupling for an exhaust system for a heavy truck that allows liquid to pass through the coupling without leakage.
Exhaust systems in truck tractors conduct exhaust gases along a relatively long path from the engine rearward of the cab to a stack or tail pipe. The pipes are subject to vibrations from the flowing gases and vibrations and bending movements imparted by the moving vehicle. To accommodate vibration and flexing, the pipe joints are joined with resilient, movable couplings.
U.S. Pat. No. 5,145,215 to Udell shows one such resilient coupling. The device includes two sleeve members 16, 17 that join in an overlapping manner. The end edges of the sleeves are turned outward and inward, respectively, to retain a spacer member 48 between the sleeves. The sleeves are surrounded by a bellows 10, which is, in turn surrounded by a braided wire fabric 23. The ends of the assembly are received in end caps. The end caps are mounted to the adjacent pipe ends to provide the coupling.
With the increasing use of exhaust after-treatment devices and with stricter controls on exhaust products, truck exhaust systems may in the future be called on to carry liquid material to treat the combustion products or to clean or regenerate exhaust after-treatment devices, such as diesel particulate filters, oxidizers, or catalyzers. The liquid material may be as a condensate or atomized form, and may include automotive or diesel fuel, urea, ammonia, or some other combustive, oxidizing or catalyzing agent.
The present invention provides a flexible pipe coupling system that eliminates components and associated cost and complexity of known devices, while providing a coupling allowing liquid to pass without leakage.
According to the invention a flexible sleeve joins an upstream pipe to a downstream pipe. A guide tube extends from an outlet end of the upstream pipe through the flexible sleeve into an inlet end of the downstream pipe. The guide tube carries flow through the flexible sleeve area and allows the flow to exit into the downstream pipe. An outlet of the guide tube is disposed within the downstream pipe of the coupling, and is spaced from the internal walls of the downstream pipe. This ensures that all flow passes the joint area into the downstream pipe and isolates the guide tube from the downstream pipe to prevent the transmission of vibration.
According to an aspect of the invention, the guide tube may be shaped as a straight cylinder. Alternatively, the guide tube has a frustoconical shape that converges at an outlet end. This second embodiment allows the upstream pipe and the downstream pipe to have the same diameter, the convergence of the guide tube providing the spacing between the guide tube and downstream pipe inlet.
According to another aspect of the invention, an outlet of the guide tube may include a radially outwardly flaring mouth to improve the pressure loss at the outlet of the guide tube.
According to another aspect of the invention, an inlet end of the downstream pipe may be shaped with a rim that converges radially inwardly. The rim of the downstream pipe helps prevent backflow of liquid into the flexible sleeve area.
According to one embodiment, the guide tube is a separate component fastened to the outlet end of the upstream exhaust pipe. According to an alternative embodiment, the guide tube is a formed extension of the upstream pipe.
The invention provides a low cost, reliable device. The flexible sleeve allows the upstream exhaust pipe and downstream exhaust pipe to move relative to one another, but the sleeve does not need to be liquid tight. The internal guide tube carries liquid and exhaust gas flow through the coupling joint without leakage.
The invention is particularly applicable to newer exhaust systems which may carry liquids for regenerating exhaust after-treatment devices, such as particulate filters, oxidizers, and catalyzers.
The invention will be better understood by reference to the following detailed description read in conjunction with the appended figures, in which:
A flexible sleeve 30 receives the outlet end 12 of the upstream pipe 10 and the inlet end 22 of the downstream pipe 20. Clamps 40, 42 secure the flexible sleeve 30 to the outer surfaces of the upstream pipe 10 and downstream pipe 20. The flexible sleeve 30 in a preferred embodiment is a metal spiral wound tube that provides resilient bending in a plane perpendicular to the gas flow direction A, and accommodates compression and tension in the flow direction. The spiral forms rings that are interlocked to provide a closed surface. The sleeve is preferably stainless steel. A flexible sleeve as described is available, for, example, from Federal Hose, Inc. of Painesville, Ohio, Riker Products of Toledo, Ohio and Tru-flex Metal Hose Corp. of West Lebanon, Ind. Other similarly functional flexible sleeves could be substituted.
A guide tube 50 extends from the outlet end 12 of the upstream pipe 10 into the inlet 22 of the downstream pipe 20. The guide tube 50 is spaced radially from the downstream tube 20 to prevent the transmission of vibration therebetween. The guide tube 50 may be formed a cylinder, which is illustrated and described in connection with
Preferably, the downstream end 54 of the flow guide 50 is shaped with a radially outward flaring rim 56 that aids flow in exiting from the flow guide.
Preferably also, the inlet end 22 of the downstream pipe 20 is shaped with a radially inwardly converging rim 24 to help prevent liquid backflow into the flexible sleeve 30 area. The bend in the rim should be enough to act as a catch to prevent liquid backflow, but not interfere with the free movement of the outlet of the guide tube.
Other means for preventing backflow into the sleeve area may be substituted. For example, a ring 26 may be secured inside the inlet of the downstream pipe as shown in
As illustrated in
The downstream pipe 20 is also formed with the preferred inlet rim 24 converging radially inward. The guide tube 51 shown in
In the embodiment illustrated in
The invention has been described in terms of principles and preferred embodiments and components. Those skilled in the art will understand that the invention may be practiced with substitutions for preferred components without departing from the spirit and scope of the invention as defined in the appended claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US05/46701 | 12/22/2005 | WO | 00 | 6/6/2008 |
