DE9318864U1 - Exhaust tailpipe for vehicles with petrol engines - Google Patents

Description

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DESCRIPTION

Exhaust tailpipe for motor vehicles with petrol engines.

State of the art

Series-produced vehicles are designed to meet the applicable emissions regulations. Official proof that a vehicle complies with the regulations is provided by an emissions test on a reference vehicle that is specified in detail. The driving cycle used characterizes typical operation in everyday traffic.

The emissions regulations are constantly being tightened by the legislature. Even today, complex catalyst concepts are required in order to comply with the strict limits. The catalysts are positioned as close to the engine as possible so that they start up early after a cold start. In some cases, so-called starting catalysts are also installed.

It can be assumed that standard catalyst concepts represent an optimum in terms of function, durability and costs according to the current state of the art.

Basically, at high gas throughputs, i.e. at high load and speed, the conversion rate of a catalyst decreases depending on the space velocity and thus the proportion of unconverted exhaust gas increases. This proportion is

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This is made even greater by the fact that enrichment is often carried out for engine reasons, but also to protect the standard catalyst at high loads.

The exhaust gas flowing uncleaned through the series catalyst is particularly well suited for catalytic aftertreatment in the control range of lambda-controlled concepts due to its chemical composition.

The situation for new and used vehicles is as follows:

The majority of vehicles with petrol engines in circulation are either still completely "uncleaned" or at best have a simple cleaning device with limited effect such as exhaust gas recirculation, additional air injection, "unregulated" catalytic converter, etc.

Even in modern new vehicles with lambda control and 3-way catalytic converter, there is always a more or less large unconverted residual portion in the exhaust gas emitted, depending on the operating range.

Since catalytic converters "age" in everyday use and thus continuously lose their effectiveness, this residual proportion increases over the service life. Emissions tests on used vehicles have shown that, as a result of the operational aging process, the applicable limit values are often no longer complied with at an early stage.

Devices that take this considerable potential for improving exhaust emissions into account are not yet available. Only age-related deterioration in exhaust emissions can be largely eliminated by replacing the aged parts.

problem

The invention specified in claim 1 is based on the problem of creating a device which provides additional exhaust gas purification in particular when standard catalyst systems in motor vehicles with gasoline engines do not work optimally due to their design or no longer work optimally due to aging.

However, the device should also be applicable to motor vehicles that do not yet have a catalytic converter.

It should also be suitable for both standard installation in new vehicles and for subsequent installation in used vehicles.

For used vehicles with excessively aged catalytic converters, a cost-effective alternative solution should be created to replace the standard catalytic converter.

invention

This problem is solved with the exhaust tailpipe according to claim 1.

Beneficial effects of the exhaust tailpipe

The exhaust tailpipe according to claim 1 is used for catalytically treating uncleaned or partially cleaned exhaust gases from motor vehicles with gasoline engines.

The highest conversion rates are achieved in vehicles with intact lambda control that are operated in the control range and whose standard catalyst has become less effective.

The exhaust tailpipe according to claim 1 is also effective when a catalytic converter vehicle is driven in load ranges in which optimal exhaust gas control and purification no longer takes place, for example at full load.

Good conditions for the use of the exhaust tailpipe according to claim 1 are also offered by vehicles that have either no exhaust gas purification system or only a less effective one.

The positioning of the exhaust tailpipe according to claim 1 after the last silencer has the advantage that the thermal aging due to relatively low operating temperatures is much lower than with standard catalytic converters. This results in long service lives and, in vehicles with catalytic converters, increasing conversion quantities due to the faster diminishing effect of the standard catalytic converter.

The activation of the tailpipe catalyst has a modulating influence on the exhaust noise.

The red glow of the tailpipe catalyst, which occurs in individual cases and is visible from the rear, can be used as an optical signal for the ongoing cleaning process.

Further developments of the invention

The optional design according to claim 2 enables optimal use of the available installation space and fulfillment of optical requirements.

Claim 3 ensures that mass-produced catalysts can be used.

With the help of claim 4, even complicated special solutions for confined installation conditions can be created.

The optional use of metal or ceramic supports according to claim 5. enables cost optimization depending on installation space, design and production facilities.

The optional coating according to claim 6 allows the manufacturer to determine the optimal cost/benefit ratio for the respective application.

The structural design according to claim 7 provides the basis for optimizing the exhaust tailpipe according to claim 1, depending on the quantity and user. Technical requirements, such as weight minimization, can also be satisfied in a variable manner.

The various connection options according to claim 8 take into account the options of the manufacturers on the one hand and the requirements of the customers on the other hand.

The further training according to claim 9 creates the possibility to react to noise-related requirements and wishes.

The cone design according to claim 10 allows a tailpipe version to be adapted to different vehicles by sawing off the cone to the respective connection diameter. In addition, the inflow conditions as well as the light-off time and conversion rate of the catalyst can be positively influenced by a suitable geometric and structural design of the cone.

The air supply according to claim 13 ensures, if necessary, that the incoming exhaust gas is processed in the best possible way for subsequent cleaning in the catalyst tailpipe.

By applying an early-starting coating according to claim 6 and/or installing a heating device according to claim 14 and/or using a stepped catalyst unit according to claim 15, the start-up time of the tailpipe catalyst after a cold start is shortened and its cleaning effect is increased. Effective thermal insulation of the exhaust system works in the same direction.

With one of the measures according to claim 16, the temperature on the outer surface of the tail pipe (1) is lowered and the heat dissipation that impairs the continuous cleaning effect of the catalyst (2) is reduced. A reduction in the outer surface temperature can also be achieved by pushing the cone (6) according to claim 10 into the cladding tube (3) so far that the outer cells are no longer flowed through.

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With an intrusion protection according to claim 17, the risk of deliberate damage to the catalyst carrier can be limited.

The support device according to claim 18 is intended to help counteract vibration fractures in the area of the rear silencer and standard tailpipe in particular when an exhaust tailpipe with a relatively large mass has to be used.

With the help of a measuring device according to claim 19, the driver can monitor the function of the catalytic converter and positively influence its start of operation and thus its effectiveness through his driving style. This also applies in the event that the catalytic converter has "gone out" during the journey due to excessive cooling.

The use of several catalysts according to claim 20 can, under appropriate conditions, also contribute to improving the quality of the exhaust gases. Optical requirements can also be met in this way.

63067 Offenbach, 08.12.93

Description of implementation examples

Various embodiments of the exhaust tailpipe are described using Figures 1 to 3. The figures show in detail:

Figure 1 shows a straight exhaust tailpipe in a cylindrical design. A perforated pipe section (4), the catalyst (2) and a cone (6) with a cylindrical pipe attachment are inserted into the tailpipe from the front. On the outlet side, they are supported under pre-tension on the flange of the tailpipe (1). On the inlet side, the cone (6) is welded peripherally to the tailpipe (1). In the cavity between the perforated pipe section (4) and the tailpipe (1) there is sound-insulating material (5).

Figure 2 shows a tailpipe (1) that ends in a curve after the catalyst (2).

Figure 3 shows a straight exhaust tailpipe in which the cladding pipe (3) of the catalyst {2) is also the tailpipe. The cylindrical pipe attachment of the cone (6) is placed over the tailpipe/cladding pipe (1 and 3) and welded to it. On the inlet side, the cone begins with a slotted pipe section (7). There is a protective grille (8) between the catalyst (2) and the end of the tailpipe/cladding pipe (1 and 3).

Figure 3 also shows alternative cross-sectional shapes of the casing (3) and/or end pipe (1), distinguishing between round cross-section (3a), elongated round (3b) and elliptical (3c).

63067 Offenbach, 08.12.93

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Claims (21)

PROTECTION CLAIMS 1. Exhaust tailpipe for motor vehicles with a gasoline engine, characterized in that a catalyst (2) for exhaust gas purification is integrated into the tailpipe (1). 2. Exhaust tailpipe according to claim 1, characterized in that the tailpipe (1) and/or catalyst (2) preferably have a round (3a), oblong round (3c) or elliptical (3b) cross-section. 3. Exhaust tailpipe according to claim 1 or 2, characterized in that tailpipe (1) and catalyst (2) in the catalyst area are preferably coaxial and straight. 4. Exhaust tailpipe according to one of claims 1 to 3, characterized in that the tailpipe (1) itself and/or adaptive parts of the tailpipe before and/or after the catalyst (2) are preferably straight or curved. 5. Exhaust tailpipe according to one of claims 1 to 4, characterized in that the catalyst (2) preferably has a metal or ceramic carrier. ö.Exhaust tailpipe according to one of claims 1 to 5, characterized in that the catalyst (2) is preferably provided with an oxidizing or an oxidizing and reducing coating. 7. Exhaust tailpipe according to one of claims 1 to 6, characterized in that the cladding tube (3) of the catalyst (2) is simultaneously designed as a tailpipe (1), or that the catalyst (2) with cladding tube (3) is inserted into the tailpipe (1). 8. Exhaust tailpipe according to one of claims 1 to 7, characterized in that the cladding tube (3) is connected to the tailpipe (1) preferably in a force-fitting, form-fitting or welding manner. 9. Exhaust tailpipe according to one of claims 1 to 8, characterized in that in the tailpipe (1) in addition to the catalyst (2) a perforated inner pipe (4) and sound-insulating materials (5) are arranged. 10. Exhaust tailpipe according to one of claims 1 to 9, characterized in that the tailpipe (1) is provided with a cone (6) and/or a pipe socket (7) which enables a connection to the shortened standard tailpipe or the rear silencer, preferably by welding, flanging or pushing into one another and clamping. The cone (6) is either pushed into or slipped over the casing or tailpipe with its cylindrical pipe attachment. 11. Exhaust tailpipe according to one of claims 1 to 10, characterized in that all metallic components are preferably made of stainless steel. 7. Exhaust tailpipe according to one of claims 1 to 11, characterized in that the tailpipe (1) is preferably untreated on the outside, chrome-plated, enamelled or provided with another protective and optionally decorative surface treatment. 13. Exhaust tailpipe according to one of claims 1 to 12, characterized in that a connection piece for additional air is mounted in front of the catalyst (2). 14. Exhaust tailpipe according to one of claims 1 to 13, characterized in that a heating device is installed in front of or on the catalyst (2). 15. Exhaust tailpipe according to one of claims 1 to 14, characterized in that a catalyst unit with a stepped number of cells and geometry is used. 16. Exhaust tailpipe according to one of claims 1 to 15, characterized in that an air gap is provided between the tailpipe (1) and the cladding tube (3) if required. Alternatively, the cladding tube (3) can be double-walled with an air gap. 17. Exhaust tailpipe according to one of claims 1 to 16, characterized in that an ingress protection, for example a resistant grid (8), is installed between the catalyst (2) and the tailpipe end. 18. Exhaust tailpipe according to one of claims 1 to 17, characterized in that the tailpipe (1) is provided with a support device in individual cases. 19. Exhaust tailpipe according to one of claims 1 to 18, characterized in that the tailpipe (1) or the catalyst (2) is preferably provided on the outside or inside with a temperature measuring device. 4" 20. Exhaust tailpipe according to one of claims 1 to 19, characterized in that, depending on the starting basis, spatial conditions and optical and technical requirements, one, two or more tailpipes and catalysts are used per vehicle. 21. Exhaust tailpipe according to one of claims 1 to 20, characterized in that the construction and equipment are modified for installation in diesel vehicles.