Motor vehicles – Bodies – With means for handling exhaust of a motor
Reexamination Certificate
2001-07-20
2003-03-25
Johnson, Brian L. (Department: 3618)
Motor vehicles
Bodies
With means for handling exhaust of a motor
C180S296000, C248S058000
Reexamination Certificate
active
06536548
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an exhaust system for a motor vehicle comprising a vehicle body and an internal combustion engine. The exhaust system has an exhaust which is intended for connection to the internal combustion engine and has at least one housing of a silencer and/or of a catalytic converter with a housing casing, having essentially a material thickness of not more than 1 mm, and two housing ends, at least one of which is rigidly connected to a metallic pipe, having a material thickness of not more than 1 mm, for carrying the exhaust gas. The exhaust system furthermore has retaining means for holding the exhaust on the vehicle body.
The exhaust system is intended, for example, for a car but may also be used for another motor vehicle—for example a truck or bus. The internal combustion engine may be formed as a SI or diesel engine.
2. Description of the Prior Art
EP 0 807 749 A and the corresponding U.S. Pat. No. 6,058,702 disclose exhaust systems which have pipes, a catalytic converter and at least one silencer, at least one of the pipes, the casing and the end walls of the housing of the or each silencer having a material thickness of not more than 1 mm and, preferably, not more than 0.8 mm. Because of this light-weight construction, such an exhaust system has a very low weight. The exhaust systems have retaining means with holders which connect the housing of each silencer, in the vicinity of the housing ends, to the bottom of the vehicle. The holders have, for example, metallic retaining members fastened to the housing casing by spot welding or another welding method. Because of the small material thickness of the hosing casing, however, it is difficult to weld the retaining members in a stable manner to the housing casing without cracks and/or holes being formed in the latter during welding or later during the use of the motor vehicle. In addition, at least a part of the exhaust system and in particular at least one silencer are usually arranged on the underside of the vehicle bottom. There is generally only a small amount of space between the vehicle bottom and the surface on which the vehicle stands or drives. However, the holders fastened below or above the housing casing also occupy a certain height and may reduce the height region available for the housing casing and hence the maximum possible cross-sectional dimensions of the silencer and its silencing effect.
The U.S. Patent No. 3,270,992 discloses an exhaust system with a resonator and a tail pipe and a hanger for holding the tail pipe on the vehicle body. The hanger has an upper mounting bracket, a lower mounting bracket, a flexible loop connecting the two brackets to one another and a clamp. The clamp extends around the tail pipe, is tightened by a screw and secures a leg of the lower mounting bracket to the tail pipe.
U.S. Patent No. 3,270,992 does not disclose the wall thicknesses of the pieces and of the resonator housing. It seems probable that wall thicknesses usual in the prior art and amounting to at least about 1.5 mm were provided and that the exhaust is rather heavy. If the wall of the tail pipe were made thinner, it would likely be compressed at places and deformed by the asymmetric forces transmitted to the pipe by the clam and the leg of the lower mounting bracket disposed between the upper side of the pipe and the clamp when the clamp is tightened by the screw and/or when the exhaust is submitted to accelerations directed, for example, upward or downward. In this context, it should be noted that very great approximately vertical accelerations may be applied to the exhaust during the use of the vehicle, when the latter, for example, drives at high speed over a hole or a bump or the like. Moreover, movements, and particularly longitudinal movements, of the tail pipe may tilt the lower mounting bracket so that the latter presses strongly onto the upper side of the tail pipe and may deform the latter. Since the flexible loop is rather weak and moreover slidable relative to the upper mounting bracket, the tail pipe can moreover make large movements in more or less all directions. This is a further reason that the pipes must have rather thick and heavy walls for enabling them to bear large inertial stresses. The movable exhaust parts must also be large distances away from the vehicle body. This is particularly disadvantageous for exhaust parts arranged in the tunnel of the vehicle bottom.
An exhaust system disclosed in DE 297 11 764 U has a silencer. This is fastened at one of its ends with retaining means which have two curved rods consisting of an aluminium alloy and having a solid cross-section. The first of these two rods has a curved end section on which rest two likewise curved steel sleeves which are welded to one of the two end walls of the silencer. That end section of the first rod which faces away from the curved end section is connected by a rubber member to an end section of the second rod. Its other end section rests in a steel sleeve which is welded to a retaining element which in turn is fastened to the vehicle bottom.
DE 297 11 764 U contains no information about the material thicknesses of the pipes serving for carrying the exhaust gas and of the housing of the silencer. It therefore appears plausible that material thicknesses usual in the prior art and amounting to at least about 1.5 mm were provided, so that the exhaust is rather heavy. It would in particular also be virtually impossible to weld the steel sleeves resting on the first rod to a silencer end wall having a thickness of less than about 1.5 mm without cracks and holes forming in the housing during welding or later during the use of the motor vehicle. Furthermore, the steel sleeves are fastened only by being pressed onto the rods. Since the rods consist of an aluminium alloy, it would furthermore scarcely be possible to weld the steel sleeves to them. Since the housing of the silencer and hence the steel sleeves fastened to it are considerably heated temporarily during operation, thermally caused dimensional changes and deformations occur and may lead to loosening of the connection of the pressed-on sleeves to the first rod. Moreover, the steel sleeves arranged on the first rod must be curved the same way as the end section of the rods which hold them, which makes the manufacture more expensive. Furthermore, mounted between the rods consisting of an aluminium alloy and the steel sleeves is an insulating layer or insulating sheet which is required for preventing electrochemical corrosion and also makes the manufacture more expensive and may impair the strength and durability of the press fit. The retaining means disclosed in DE 297 11 764 U are furthermore scarcely suitable for mounting a silencer which is present in the tunnel of a vehicle bottom.
DE 30 26 730 A and DE 31 27 746 A disclose exhaust systems in which the housing of a silencer or pipes of the exhaust are suspended from the vehicle body by means of at least one rubber ring. If a force is exerted on an exhaust part held in this manner, the rubber rings initially offer only very little resistance to a deflection of the exhaust from its rest position. Only when the deflections of the exhaust part reach limits of about 1 cm to 2 cm or even more does the resistance generated by the rubber rings increase abruptly. Retaining means comprising at least one rubber ring therefore have the disadvantage that the or each suspended part is virtually freely movable in particular upwards and also in all approximately horizontal directions within certain ranges which are usually at least 1 cm or more. Exhaust parts suspended in this manner must therefore be large distances away from the vehicle body and—in the case of the arrangement in the tunnel of the vehicle bottom—in particular from the walls of the tunnel. Furthermore, exhaust parts suspended in this manner and the parts connected to them must have thick walls so that the exhaust is sufficiently strong.
SUMMARY OF THE INVENTION
It is the object of the present invent
Alexnat John W. Jörg
Steenackers Pieter Delfina
Fischmann Bryan
Johnson Brian L.
Scambia Industrial Developments AG
Sidley Austin Brown & Wood LLP
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