DE102012106303A1 - Gas exhaust system, useful for internal combustion engine of motor vehicle, comprises sensor to detect temperature, gas concentration, air-fuel ratio and oxygen concentration of exhaust gas, and protective elements placed in exhaust line - Google Patents

Abstract

The exhaust system comprises a sensor (4) i.e. lambda probe, for detecting temperature, gas concentration, air-fuel ratio and oxygen concentration of an exhaust gas, protective elements (3, 31) consisting of Water-binding and water-donating substances, where the protective elements are operated in a first operating condition for binding of condensed exhaust gas stream and in a second operating condition for dispensing of a bound water in a layer. The protective elements are arranged as a separate component in an exhaust line (21) for exhausting gas stream along cross-section. The exhaust system comprises a sensor (4) i.e. lambda probe, for detecting temperature, gas concentration, air-fuel ratio and oxygen concentration of an exhaust gas, protective elements (3, 31) consisting of Water-binding and water-donating substances, where the protective elements are operated in a first operating condition for binding of condensed exhaust gas stream and in a second operating condition for dispensing of a bound water in a layer. The protective elements are arranged as a separate component in an exhaust line (21) for exhausting gas stream along cross-section. Water-binding and water-donating substances of the protective elements are increased with respect to the maximum amount of condensed water in the exhaust system. The water-binding and water-donating substances are of porous structure with high gas permeability. The porous structure is a honeycomb structure or a spherical structure and is embedded with a metallic structure. The system further includes a turbo supercharger fitted in the exhaust line of an internal combustion engine. The protective element is placed between the turbo supercharger and the probe.

Description

The invention relates to an exhaust system for an internal combustion engine with at least one sensor for detecting temperature, gas concentration, air-fuel ratio, oxygen, etc., in particular a lambda probe and a protective element protecting the sensor and its function, consisting from a substance which is capable of binding water in the exhaust gas flow in a first operating state and being able to dispense the bound water in a second operating state.

Pollutant concentrations in exhaust gases of internal combustion engines, especially in motor vehicles are reduced by controlling the fuel-air mixture supplied to the combustion by detecting the fuel-air ratio in the exhaust stream via sensors, so-called lambda probes. For this, it must be ensured that the sensor detects the correct values in all operating states of the internal combustion engine and supplies them to the engine management system. Such probes are particularly sensitive when water droplets hit the probe surface, which in extreme cases can lead to the destruction of the probe or at least to malfunctions. The formation of condensation in the exhaust system of an internal combustion engine is simply unavoidable. Therefore, it is known, the sensor through him enclosing protective caps, protective covers u.ä. seek to protect, on the one hand prevent mechanical damage and on the other hand, influences such as by falling water droplets ("water hammer") to reduce or prevent. For example, from the EP 0 880 025 B1 , from the US 5 073 247 and from the DE 10 2004 020 139 A1 Such protective caps, protective covers or protective elements known. These known protective structures should prevent water access to the actual sensor.

From the EP 1 807 691 B1 is a protective element for a sensor, in particular a lambda probe in the exhaust system of an internal combustion engine, in which the molded onto the probe protective element consists of a binding in a first operating water and in a second operating state, the bound water again releasing layer. However, this known solution protects only the immediate area around the sensor by the arrangement of the protective element; However, the volume for storing water, which is required in the majority of operating states and in particular during a cold start after a longer standstill, can not be made available via such a protective element. As a result of the arrangement, only a small part of the exhaust gas flow is conducted through the protective element or only a small proportion of the condensation water that is present as a result of the cooling of the exhaust gas line after the internal combustion engine has been shut down.

The present invention is therefore an object of the invention to provide an effective protection for sensors in an exhaust system of an internal combustion engine, can be ruled out with high certainty that by water mist, water droplets - especially in the starting phase of an internal combustion engine - measurement errors or even permanent Damage to the sensor may occur.

This object is achieved according to the invention in that the protective element is arranged as a separate component in the exhaust gas flow, the exhaust line substantially cross-section filling directly in front of the or the probes.

Ideally, the water-binding and water-releasing substance, from which the protective element is essentially constructed, is capacitively designed for the maximum amount of condensate forming in the exhaust system.

• – Zeolith, insbesondere Zeolith A, X und/oder Y und/oder Faujasite;
• – Aluminiumoxid;
• – monoklin kristallisierende Silikalit-Mineralien.

The water-binding and water-releasing substance is preferably a substance having a water-barrier porous structure of high gas permeability. He may include at least one of the following materials:

• Zeolite, in particular zeolite A, X and / or Y and / or faujasites;
• - alumina;
• - monoclinic crystallizing silicalite minerals.

The porous structure of the fabric or of the fabric arrangement of or in the protective element can be embodied in any geometric arrangement, provided that water impermeability is ensured with high gas permeability. Particularly preferred is a honeycomb or a spherical structure. In any case, the porous structure can be integrated into a robust metal structure and thus form the independent component in the exhaust gas flow, via which the entire gas flow can be conducted in a water-purifying manner.

For the skilled person it goes without saying that the arrangement or use of the protective element according to the invention is independent of the type of internal combustion engine - petrol or diesel principle - is.

A particularly advantageous application of the protective element according to the invention results in equipped with turbochargers internal combustion engines: by the arrangement of the protective element in the exhaust gas flow between the turbocharger and sensor / lambda probe can with appropriate Choice of the fabric structure or choice of the arrangement of the substance in the protective element, the turbulence caused swirl flow of the exhaust gas rectified by the passage in the protective element and thus a significantly improved flow of the catalyst can be achieved.

The above-mentioned materials, which form the substance for the protective element, show at very high temperature resistance - in some cases up to 1000 ° C - water-storing properties up to temperatures of about 200 ° C. They heat up (and their environment) quickly very strong, so that in any case this area of the exhaust system, but especially the lambda probe together with the downstream catalytic converter are heated quickly and effectively in the starting phase.

From temperatures above about 200 ° C, the materials mentioned give the stored water in the form of water vapor again, so that the protective element regenerates during operation, so to speak, and is available again for the next cold start to accommodate the condensate.

The features and advantages of the invention will be explained in more detail in the following example description with reference to the drawing (schematic representation).

It shows:

1 the arrangement of the protective element according to the invention in the exhaust line of an internal combustion engine (naturally aspirated engine); and

2 the arrangement of the protective element according to the invention in an internal combustion engine with turbocharger.

In 1 is with 1 schematically an internal combustion engine - a suction motor - shown. About the with 2 designated exhaust manifold, the exhaust gases in the exhaust system 21 initiated. In the exhaust system 21 and its cross-section totally covering is a protective element 3 arranged. This protective element 3 consists in a preferred embodiment of a support body 31 from a metal structure in which substances with a porous structure and high water absorption capacity absolutely water passage blocking are embedded at the same time high gas permeability and lining the exhaust system substantially cross-sectional filling. Such substances may be zeolite, alumina or monoclinic crystallizing silicalite minerals. In this designed as an independent component in the exhaust stream and arranged protective element 3 the condensate is first bound, for example after a cold start, and released again only at higher operating temperatures - eg above 200-250 ° C - in gaseous form. Thus, the sensor arranged downstream in the exhaust gas flow becomes 4 = Lambda probe, with its highly sensitive measuring elements 41 is located directly in the exhaust stream, effectively protected against "water hammer"; Mechanically, the measuring elements are effective thanks to a simply constructed protective tube 5 eg made of ceramic.

In the exhaust gas flow following to sensor / lambda probe 4 is a catalyst in a known manner 7 arranged.

In the embodiment according to 2 is also schematically an internal combustion engine 11 represented, whose exhaust via exhaust manifold 22 turbochargers 23 be supplied. The turbochargers 23 relatively immediately downstream in the exhaust stream is a protective element 32 arranged, in its construction essentially the protective element 3 . 31 equivalent. With appropriate design of the structure of the protective element 32 or its substances, the swirling flow of the exhaust gases produced in the turbocharger is rectified and the catalyst is flowed with the same direction 8th fed. Between protective element 32 and catalyst 8th is in the exhaust stream in a known manner - see the exemplary embodiment 1 - a sensor / a lambda probe 43 with a protective tube protecting the measuring elements 44 , which is located directly in the exhaust stream, arranged.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine (naturally aspirated engine)

2

exhaust manifold

3

protection element

4

Sensor / oxygen sensor

5

thermowell

7

catalyst

8th

catalyst

11

Internal combustion engine (charged)

22

exhaust

23

turbocharger

31

protection element

32

protection element

41

measuring elements

43

Sensor / oxygen sensor

44

thermowell

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0880025 B1 [0002]
• US 5073247 [0002]
• DE 102004020139 A1 [0002]
• EP 1807691 B1 [0003]

Claims (7)

Exhaust system for an internal combustion engine with at least one sensor ( 4 . 43 ) for detecting temperature, gas concentration, fuel-air ratio, oxygen and the like, in particular a lambda probe, and a sensor ( 4 . 43 ) and its functions protective protective element ( 3 . 31 . 32 ), Consisting of a substance which is in a first operating condition for binding of condensate in the exhaust gas stream and in a second operating condition for delivery of the bound water in the location, characterized in that the protective element ( 3 . 31 . 32 ) as an independent component in the exhaust stream the exhaust line ( 21 ) substantially cross-sectionally lining directly in front of the / the sensor (s) ( 4 . 43 ) is arranged. Exhaust system according to claim 1, characterized in that the water-binding and water-releasing substances of the protective element ( 3 . 31 . 32 ) Capacitive to the maximum in the exhaust system forming condensate are designed. Exhaust system according to claim 1 or claim 2, characterized in that the water-binding and water-releasing substances are formed with a porous structure of high gas permeability and comprise at least one of the following: - zeolite, in particular zeolite A, X and / or Y and / or faujasites ; - alumina; - monoclinic crystallizing silicalite. Exhaust system according to claim 3, characterized in that the porous structure is a honeycomb-shaped structure. Exhaust system according to claim 3, characterized in that the porous structure is a spherical structure. Exhaust system according to one of the preceding claims, characterized in that the porous structure is incorporated in a metal structure. Exhaust system for one with at least one turbocharger ( 23 ) in the exhaust line equipped internal combustion engine ( 11 ) with at least one sensor ( 43 ) and at least one protective element ( 32 ) according to one of the preceding claims, characterized in that the protective element ( 32 ) in the exhaust gas flow close to the turbocharger ( 23 ) and probes ( 43 ) is arranged.

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