DE9417043U1 - Exhaust system for compact cars - Google Patents

Description

Description:

The invention relates to exhaust systems for compact cars, comprising an exhaust catalyst, a silencer, at least one manifold pipe and a tailpipe according to the preamble of claim 1.

A silencer with an integrated exhaust gas catalyst is known from US 4,894,987. The silencer housing consists of two deep-drawn outer sheet metal half-shells and two deep-drawn inner sheet metal half-shells. All half-shells have a flat, circumferential flange where they touch when assembled, so that all parts can be connected to one another in a gas-tight manner with a single circumferential weld seam. By appropriately shaping the inner and outer shell sheets, exhaust gas-carrying pipes, which are perforated in some areas, and expansion and resonance chambers are created inside the housing. The catalytically active body sits in its own inner housing with an inlet funnel and outlet funnel, which is inserted into a suitably shaped recess between the two inner shell sheets.

Because it is manufactured from a total of four large-area half-shell sheets and because a separate housing is used for the catalyst body, the result is a heavy, expensive and large-volume housing whose shape is reminiscent of a coffin. It is not conceivable that it could be used in European compact cars.

The present invention is therefore based on the object of specifying an exhaust system of the type mentioned at the beginning, which is simple, light and inexpensive and yet reliable in operation, a high effectiveness of all functions, in particular

which ensures the catalytic cleaning function and which can also be efficiently manufactured in the factory.

This object is achieved by an exhaust system with the features of claim 1.

Thanks to the inclination of the inlet funnel against the longitudinal axis of the catalyst body, the flow to the front surface of the catalyst body is optimally even, resulting in an optimal catalytic cleaning effect per catalyst surface. Thanks to the mounting of the catalyst body in the silencer housing, a separate inner housing is no longer required, making the construction simpler, cheaper and lighter. All auxiliary components that were previously considered necessary in many catalyst designs to fix the catalyst body axially in the housing and to protect the expansion mat from exhaust gas pulsations are also no longer required. This also simplifies the construction and assembly, reduces the weight and reduces the price.

Of particular advantage, however, is the design that creates the connection between the manifold pipes coming from the engine and the silencer-catalyst housing. In a change to what was previously usual, each manifold pipe is inserted directly into the inlet funnel of the housing, with the ends of the manifold pipes initially being combined to form a multiple pipe, where they touch each other over a large area and ultimately also in an exhaust-tight manner. The free end of the inlet funnel is designed accordingly so that it encloses the multiple pipe flush.

Thanks to this design, it is possible to connect the inlet funnels and the manifold pipes using a single circumferential

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Weld seam to connect gas-tight. This simplifies and speeds up assembly.

Preferably, all manifold pipes are the same length. This leads to optimal power and torque coordination and acoustics, i.e. good sound insulation.

According to a preferred embodiment of the invention, two partition walls and two exhaust-carrying, partially perforated pipes penetrating these are provided in the silencer part of the housing, whereby two expansion chambers and a resonance chamber are formed. One of the exhaust-carrying pipes simultaneously forms the coupling neck of the resonance chamber. The use of a coupled resonance chamber makes it possible to specifically adjust the silencer's damping characteristics for certain frequencies if the engine for which the exhaust system is intended generates such particularly disturbing frequency components.

According to a preferred embodiment of the invention, the housing has a pronounced egg-shaped cross-section. In many cases, this allows for a particularly space-saving installation of the exhaust system between the engine and the body. In addition, the radiation of structure-borne noise is low.

As already mentioned, all manifold pipes are inserted directly into the inlet funnel in front of the catalytic converter, there is no longer any special mixing section. For this reason, it is recommended that the lambda sensor required for the proper operation of the exhaust gas catalytic converter be installed directly into the inlet funnel in front of the catalytic converter body, for which a corresponding nozzle is provided.

The drawing shows the invention in the form of a

The following example shows

Fig. 1 shows a top view of an exhaust system for a three-cylinder engine in a semi-transparent representation,

Fig. 2 is a side view of the exhaust system of Fig. 1 and

Fig. 3 shows a section through the exhaust system of Fig. 1 and along the line III-III in Fig. 2.

The figures show an exhaust system for a compact car with a three-cylinder engine. You can see three manifold pipes 30, 31, 32, a sheet metal housing 1 for a combined catalytic converter silencer and a tailpipe 33. The cross-section of the silencer part of the housing 1 is distinctly egg-shaped. The housing 1 itself is made up of two deep-drawn sheet metal half-shells 2, 3. The gas-tight connection is made along a circumferential sheet metal flange 4.

One end of the three manifold pipes 30, 31, 32 each has a cylindrical flange 34, the other ends are joined together to form a multiple pipe 35 and are deformed in such a way that they touch one another flatly and with as few gaps as possible. The cross-section of the multiple pipe 35 is reminiscent of a cloverleaf.

The housing consisting of the two sheet metal half-shells 2, 3 has an inlet funnel 5, the free end 15 of which is designed in such a way that it encloses the multiple pipes 35 flush and a gas-tight connection between the inlet funnel 5 and the three elbow pipes 30, 31 can be made by a single circumferential weld seam.

As can be seen in particular from Fig. 3, a catalyst body 20 is mounted directly in the housing 1 with the aid of a swelling mat 21 immediately behind the inlet funnel 5. An impression 14 running at least partially all the way around fixes the catalyst body 20 in the axial direction and protects the swelling mat 21 from the exhaust gas pulsations.

The inlet funnel 5 is inclined at an angle of at least 45 degrees against the longitudinal axis 22 of the catalyst body 20. This makes the flow onto the front surface of the catalyst body 20 extremely uniform, which leads to an optimization of the catalytic cleaning effect per catalyst surface.

The silencer part of the housing 1 is connected to the catalyst part. Its structure is conventional. The interior of the housing 1 is divided into two expansion chambers 11, 12 and a resonance chamber 13 by means of two partition walls 9, whereby exhaust gas-carrying pipes 6, 7 with perforations 16 ensure the acoustically effective exhaust gas routing. One of the pipes 6 opens into the resonance chamber 13, whereby the corresponding pipe section 18 forms the coupling neck. The other pipe 7 is tightly closed at one end 17, the other end forms a housing outlet 8, into which the tailpipe 33 can be inserted.

The inlet funnel 5 has a nozzle 19 on the side, into which a lambda probe can later be inserted. The inlet funnel 5 thus simultaneously forms the mixing section in which the exhaust gas partial flows coming from the three manifold pipes 30, 31, 32 are mixed and equalized. By dispensing with the otherwise usual mixing section, the dimensions of the entire system can be shortened accordingly, which makes it easier to install in a

Compact car is extremely advantageous

Claims (6)

• · Protection claims: 1. Exhaust system for compact cars, comprehensive - an exhaust catalytic converter and a silencer, consisting of -- a housing (1) composed of two deep-drawn sheet metal half-shells (2, 3), -- a catalytically active body (20) is integrated therein, -- an inlet funnel (5) in front of the catalyst body (20), -- exhaust gas-carrying, partially perforated pipes (6, 7) -- and at least one intermediate wall (9, 10) in the housing (1), whereby expansion spaces (11, 12) and/or resonance spaces (13) arise, - at least one manifold pipe (30, 31, 32) and - a tailpipe (33),
characterized by the features: - the cat body (20) is mounted directly in the housing (1) by means of a swelling mat (21), - the housing (15) has a partially circumferential indentation (14) that axially holds the cat body (20), - the inlet funnel (5) is inclined against the longitudinal axis of the catalyst body (20), preferably by more than 45 degrees, - one manifold pipe (30, 31, 32) is provided for each engine cylinder, - the free ends of the bend pipes (30, 31, 32) are joined to form a multiple pipe assembly (35) and are deformed in such a way that they touch each other flatly, - the free end (15) of the inlet funnel (5) is designed so that it encloses the pipe manifold (35) flush. 2. Exhaust system according to claim 1, characterized by the feature: - Inlet funnels (5, 15) and manifold pipes (30, 31, 32, 35) are gas-tight by means of a single circumferential weld seam tied together. 3. Exhaust system according to claim 1 or 2, characterized by the feature L: - all curves of the pipe (30, 31, 32) are of equal length. 4. Exhaust system according to claim 1, 2 or 3, characterized by the features: - two partition walls (9, 10) are provided, - two exhaust gas-carrying, partially perforated pipes (6, 7) are provided, - two expansion chambers (11, 12) and a resonance chamber (13) are formed, - one of the tubes (6) simultaneously forms the coupling neck (18) of the resonance chamber (13). 5. Exhaust system according to one of claims 1 to 4, characterized by the feature: - the housing (1) has a pronounced egg-shaped cross-section. 6. Exhaust system according to one of claims 1 to 5, characterized by the feature: - in the inlet funnel (5) there is a nozzle (19) for a lambda probe.