WO2012000599A1

WO2012000599A1 - Arrangement of a catalytic converter in an exhaust system

Info

Publication number: WO2012000599A1
Application number: PCT/EP2011/002743
Authority: WO
Inventors: Christian Schwarz
Original assignee: Bayerische Motoren Werke Aktiengesellschaft Patentabteilung Aj-3
Priority date: 2010-07-01
Filing date: 2011-06-03
Publication date: 2012-01-05
Also published as: US20130118164A1; EP2588722A1; CN102985651A; DE102010025804A1; WO2012000599A8

Abstract

An arrangement of a catalytic converter in an exhaust system of an internal combustion engine which can be operated with fuel containing manganese, wherein the catalytic converter is arranged in the exhaust system in a flow path of an exhaust gas of the internal combustion engine through the exhaust system, and wherein a sacrificial disc which is permeable to exhaust gas is arranged in the exhaust system upstream of the catalytic converter in the flow direction of the exhaust gas. When the exhaust-gas back pressure becomes too high for normal internal combustion engine operation owing to manganese deposits, it is necessary to exchange not the catalytic converter but rather only the cheap sacrificial disc.

Description

Arrangement of a catalyst in an exhaust system

The invention relates to an arrangement of a catalyst in one

Exhaust system of an internal combustion engine with the features of the

Preamble of claim 1.

Various national and supraregional norms lay the

Minimum requirement for petrol fuels. For example, EN 228 (European Standard) describes unalloyed petrol (Euro-Super) imported in Europe. The national edition DIN EN 228 also describes unleaded normal and superplus fuels. In the US, gasoline fuels are listed in ASTMD 439 (American Society for Testing and

Materials) specified. Petrol fuels consist of hydrocarbons, the additions of oxygenated, organic components and

May contain additives to improve their properties. Further, a distinction is made between normal and super fuel. Super fuel has a higher knock resistance to operate higher-density

Internal combustion engines. In addition, different characteristics of volatility apply to summer and winter as well as to different regions.

As described above, there are different standards for petrol fuels for different countries. This disadvantageously means that gasoline fuels in different countries may also contain different additives or impurities. Be under contamination For example, manganese, aluminum, phosphorus, silicon, zirconium,

Magnesium, zinc and calcium etc. understood. These are only given by way of example, since significantly more elements can be present in the gasoline fuel.

These elements, in particular manganese, can be negatively perceived as deposits on the end face of a catalytic converter in the exhaust system of an internal combustion engine. Interesting here is the observation that only the face of the catalyst is affected by the deposits. This can lead to the extent that over 90% of the catalyst end face are closed by the deposits, so that an exhaust back pressure is built up, which no longer permits the engine operation, d. H. The internal combustion engine lacks power and torque. Usually, such contaminated catalysts are exchanged during a workshop visit or cleaned consuming, which is very expensive and expensive for the motor vehicle manufacturer or the customer.

Therefore, this invention has for its object to provide a measure of how an exchange of such a contaminated catalyst can be avoided.

This object is achieved by the feature in the characterizing part of

Patent claim 1 solved.

The inventive arrangement of the cost-effective sacrificial disc in the flow direction of the exhaust gas before the catalyst, manganese deposits form on the sacrificial disc and not on the end face of the

Catalyst. Thus, in the case of excessive exhaust back pressure or in the course of a service interval, not the expensive catalyst must be replaced, but only the cost-effective sacrificial disc. Immediately after the replacement of the victim slide, the catalyst again shows its normal

Catalyst startup, reaching the "light-off" temperature, that is the temperature at which the catalyst is 50% full

Has conversion properties. Also the

Conversion properties of the catalyst for pollutants, such. As hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO _x ) remain virtually unchanged.

With the embodiment according to claim 2 can be prevented that the internal combustion engine fails completely, since up to a maximum of 30% of

Flow cross-section can be provided for a "run-flat" of the internal combustion engine.

The thickness of the sacrificial disc according to claim 3 has been found in practical experiments to be particularly advantageous, since the manganese deposits form in particular in the first millimeter after the end face of the catalyst, or the sacrificial disc according to the invention.

The embodiments of the sacrificial disk according to claims 4 and 5 are particularly preferred embodiments.

With the embodiment according to claim 6 flow losses can be minimized by the sacrificial disk because the spatial position of

Sacrificial disk to catalyst can be accurately positioned. Furthermore, blocking of sacrificial disk and catalyst by slipping away of the sacrificial disk is advantageously avoided.

With the embodiments according to claims 7 and 8, a simple change of the sacrificial disc is possible. Particularly preferred comes as a closure clamp, in particular a band clamp or a V band clamp or a flange, etc. are used. With the arrangement according to claim 9, the already existing compound, usually a V band clamp, can be used between the exhaust gas turbocharger and the catalyst for exchanging the sacrificial disk.

In the following, the prior art is explained in more detail with reference to a single figure.

Fig. 1 shows a photograph of a front side of a contaminated catalyst;

Fig. 1 shows a photo of a front side of a with deposits. 2

contaminated catalyst 1, which in a catalyst housing 3rd

is arranged. Chemical analyzes have shown that these

Deposits 2 consist in particular of manganese, which are the flowed by an exhaust gas of an internal combustion engine end face of the catalyst 1 in the exhaust system in the course of operation of the internal combustion engine

close when the internal combustion engine is operated with manganese-containing fuel.

In order to reduce the resulting increased exhaust back pressure, with the result of reduced line and torque, is proposed according to the invention that in the flow direction of the exhaust gas upstream of the catalyst in the exhaust system an exhaust gas permeable sacrificial disc is arranged.

Sacrificial disk is understood to mean any kind of exhaust gas permeable, temperature-resistant disk that is cheaper than a catalyst and thus can be "sacrificed" before an expensive catalyst needs to be replaced.

This sacrificial disc preferably covers a flow cross-section of the exhaust system to at least 70%, so that the deposits on the

Catalyst prevented or at least minimized, with an "emergency operation of the internal combustion engine can be ensured by a possible flow gap. Next, the sacrificial disc in the flow direction of the exhaust gas preferably has a thickness between 2 mm and 50 mm, since the manganese deposits on the end face or in the first millimeter after the end face of the catalyst, or the sacrificial disc according to the invention form.

The sacrificial disc can be constructed of a mesh and / or a knitted fabric and / or a knitted fabric and / or a catalyst support without noble metal loading, important is a necessary exhaust gas permeability. For the braid, knitted or knitted fabric, for example, metallic wire can be used. The catalyst support may be, for example, metallic or ceramic.

Preferably, the braid and / or the knit and / or the knit and / or the catalyst carrier of the sacrificial disc on a gas-permeable cell size of 20% to 400% of the cell size of the catalyst.

In order to minimize flow losses for the exhaust gas, the sacrificial disk preferably has an anti-twist device and / or an axial securing device. With the design flow losses through the sacrificial disk can be minimized because the spatial position of sacrificial disk to catalyst can be accurately positioned. A destruction of the catalyst by a due to the pulsating exhaust gas slipping away sacrificial disc is prevented.

For a simple ejection of the sacrificial disk, the exhaust system preferably has a closable opening, with a clamp, in particular a band clamp or a V band clamp or else a flange, etc. being provided for the closure thereof. Since in an internal combustion engine with an exhaust gas turbocharger now the catalyst is placed near a turbine outlet, both have approximately the same diameter, so that the sacrificial disc can be conveniently replaced by loosening the band clamp between the catalyst and the turbine housing.

Thus, if the exhaust back pressure due to manganese deposits for a normal Brennemannmäschinenbetrieb is too large, not the catalyst must be replaced, but it is only the cheap sacrificial disc replaced.

LIST OF REFERENCES:

1. Catalyst

2. deposits

3. catalyst

Claims

Arrangement of a catalyst in an exhaust system. Claims

Arrangement of a catalyst in an exhaust system of a

Internal combustion engine which can be operated with manganese-containing fuel, wherein the catalyst is arranged in a flow path of an exhaust gas of the internal combustion engine through the exhaust system in the exhaust system,

characterized in that in the flow direction of the exhaust gas before the catalyst in the exhaust system an exhaust gas permeable

Sacrifice disc is arranged.

2. Arrangement according to claim 1,

characterized in that the sacrificial disc a

The flow cross-section of the exhaust system is covered by at least 70%.

3. Arrangement according to claim 1 or 2,

characterized in that the sacrificial disc in the flow direction of the exhaust gas has a thickness between 2 mm and 50 mm.

4. Arrangement according to one of the aforementioned claims, characterized in that the sacrificial disc is made of a braid and / or a knitted fabric and / or a knitted fabric and / or a catalyst support.

5. Arrangement of next claim 4,

characterized in that the sacrificial disk has a gas-permeable cell size of 20% to 400% of the cell size of the catalyst.

6. Arrangement according to one of the aforementioned claims,

characterized in that the sacrificial disc has a rotation and / or an axial securing.

7. Arrangement according to one of the aforementioned claims,

characterized in that the exhaust system closable

Having opening for removing the sacrificial disc.

8. Arrangement according to a claim 7,

characterized in that a clamp, in particular a band clamp is provided for the closure.

9. Arrangement according to one of the aforementioned claims, wherein for the internal combustion engine, an exhaust gas turbocharger is provided with a turbine in the exhaust line,

characterized in that the sacrificial disk is disposed between the turbine and the catalyst.