DE102008040646A1 - Exhaust after-treatment device for an internal combustion engine with spark ignition - Google Patents

Abstract

An exhaust aftertreatment device (3) for gasoline engines is proposed in which a particle filter is simultaneously integrated in a precatalyst (7). This makes it possible to safely comply with limit values with regard to particle mass and particle number at low additional costs also in the future.

Description

State of the art

The invention relates to an exhaust aftertreatment device of an internal combustion engine, which operates according to the Otto method, with a pre-catalyst and a main catalyst, such as those from the DE 102 55 308.4 is known.

So far, only the components HC, NOx and CO ₂ were limited by respective limits in the gasoline engine in the exhaust gases. With the EUV and EUVI limit values coming into force in the future, the particles in the exhaust gases will also be limited. Initial investigations have shown that these limit values and above all the limit value for the number of particles provided for in the EUVI standard can not be readily controlled by internal engine measures, such as a suitable control of the internal combustion engine.

This This is especially true when the gasoline engine is equipped with direct injection is. In the gasoline direct injection (BDE) occur compared with Injection tube injection (SRE) due to the process increases particles in the exhaust gases.

Disclosure of the invention

Of the Invention is based on the object, an exhaust gas aftertreatment device provide that is simple and without significant Application effort the required limits in terms of particle number and particle mass can be safely met.

These Object is according to the invention in an exhaust aftertreatment device for an internal combustion engine with spark ignition, comprising a precatalyst and a main catalyst, wherein the precatalyst has a housing, thereby solved, that in the housing of the precatalyst, a particulate filter is integrated.

By the integration of a particulate filter according to the invention in the precatalyst, it is possible with comparatively low costs regardless of the combustion process used, namely intake manifold injection, direct injection or a Combination of both, the particle limits with relative to be able to meet low costs.

Furthermore can be achieved by integrating the particulate filter into the precatalyst exploited the available space in the engine compartment optimally and it does not have to dodge the underbody of the vehicle become.

in the The invention also relates to the term "precatalyst" a main catalyst close to the engine subsumes, since both catalysts It is common that they are arranged close to the engine and therefore comparatively hot exhaust gases are applied. By the close to the engine Arrangement of the particle filter according to the invention It is also possible to add extra Dispense sensors.

Thereby that the particle filter in the already existing housing integrated the pre-catalyst, eliminating the cost of a separate housing of the particulate filter and the "Canning" of Particulate filter. If, as in a particularly advantageous embodiment the invention provided, the precatalyst and the particulate filter can be arranged on a common carrier also the cost of an additional carrier omitted. This means that the additional costs for the particulate filter, which according to the invention in the precatalyst is integrated, are very low.

Because of the close-coupled arrangement of the invention in the pre-catalyst integrated particulate filter and the at a Otto engine known modes of operation, it is ensured that the Particle filter independently, that is without the Initiating a special regeneration mode, regenerated becomes. As a result, the clogging of the particulate filter over the entire life of the exhaust aftertreatment device effectively avoided.

This results from the fact that the gasoline engine in the homogeneous operation under regular driving conditions near the engine Exhaust temperatures of 550 ° C reached. This temperature is above the regeneration or burnout temperature for a particle filter. In addition, in the raw gas of the gasoline engine in homogeneous operation, a residual oxygen content of at least 0.5% present, the oxidation of the embedded in the particulate filter Soot during regeneration allows. Therefore, additional measures to raise the temperature the exhaust gas in the homogeneous operation of the internal combustion engine is not required.

in the Shift operation of a gasoline engine are the exhaust gas temperatures a significantly lower temperature level between 180 ° C and 400 ° C. Therefore, is an independent burnout or regeneration of the particulate filter in stratified operation not always readily possible.

at However, a gasoline engine, it is easily possible by time to switch back to the homogeneous operation at time to the Raise the temperature level to the required value.

There in petrol engines that can work in lean operation, always There is also a NOx storage catalyst, and you can regenerate of the NOx storage catalytic converter inevitably in the homogeneous operation has to switch back, is simultaneously with the regeneration the storage catalyst also regenerates the particulate filter. In In other words, through the already existing control functions the internal combustion engine, the periodic regeneration of the NOx storage catalyst cause, at the same time the regeneration of the particle filter according to the invention arranged close to the engine initiated. This means that separate functions or applications not required for the regeneration of the particulate filter but this without further action at the same time with the regeneration of the NOx storage catalyst takes place.

A Further regeneration of the particulate filter without separate control results from the operating mode "Catalyst heating". This mode is in a gasoline engine both in homogeneous operation as also initiated in shift operation after each cold start. In this Operating mode is the temperature of the exhaust gases through engine-side measures, such as an injection with multiple partial injections and late ignition angles in a BDE internal combustion engine, and late ignition angles in a gasoline engine with Intake manifold injection raised. This increases the exhaust gas temperatures in the vicinity of the precatalyst or the inventive Particulate filter to values greater than 600 ° C, so that even by the mode "catalyst heating" reliable after the engine has started the regeneration of the particulate filter becomes.

at Gasoline engines, which work with stratified charge, is also still a homogeneous phase for heating the engine and the catalyst system downstream.

This means that both gasoline engines with intake manifold injection as also in gasoline engines with gasoline direct injection and the various at Gasoline engines known operating modes, such as homogeneous operation, homogeneous lean operation, Homogeneous layer operation, homogeneous knock protection operation and layer catalyst heating In sufficiently short intervals, the exhaust gas temperatures so high be that triggered the regeneration of the particulate filter becomes.

A Sensor system of the exhaust aftertreatment device, which the state the particulate filter monitors and control functions within the engine control, which is a regeneration of the particulate filter are therefore not required. Therefore, that will Controller not additionally charged and also the application of the internal combustion engine to a specific vehicle type or a specific purpose is close to the engine by the invention built-in particulate filter not consuming.

at Internal combustion engines exclusively in homogeneous operation work can be complete due to the above constraints to renounce a control strategy for regeneration.

at Internal combustion engines, which may also be long time working in shifts, can have a model-based functionality be provided, the too long operation below the regeneration conditions in the Homogenbetrieb switches back and so the regeneration of the particulate filter triggers.

These Regeneration conditions are either measured variables the exhaust gas temperature before or are in a corresponding temperature model shown in the control unit.

Of course it would also be possible to have a loading model of the Particulate filter to implement the particle entry into the Combined particulate filter and pre-catalyst monitored and, if necessary, regeneration by the switching mode triggers.

A particularly advantageous construction of the invention Particulate filter provides that the particulate filter is a carrier, in particular has a ceramic carrier, the Filter function takes over and this carrier with catalytically active coatings is provided so that the particulate filter at the same time also acts as a precatalyst.

There In gasoline engines, the amounts of particulates compared to a diesel engine are significantly lower and also because of the previously described favorable operating conditions of the invention combined pre-catalyst and particulate filter, the burn-off the particle filter is always guaranteed, the volume of the particulate filter according to the invention relative be chosen small. For example, it is possible the volume of the combined precatalyst and particulate filter to limit 0.5 times the displacement of the internal combustion engine.

Further Advantages and advantageous embodiments of the invention are the subsequent drawing, the description and the claims removable. All in the drawing, the description and the claims disclosed features can be used both individually and in Any combination with each other essential to the invention.

It demonstrate:

1 the schematic structure of an exhaust gas aftertreatment device according to the invention; and

2 an embodiment of a particulate filter according to the invention.

In 1 is an internal combustion engine 1 with an exhaust aftertreatment device 3 greatly simplified and shown schematically. The exhaust aftertreatment device 3 includes an exhaust pipe 5 , a combined precatalyst according to the invention and particle filters 7 and a main catalyst 11 , The flow direction of the exhaust gas through the exhaust pipe 5 is by arrows 9 indicated. At the in 1 illustrated embodiment, the inventive precatalyst and particulate filter 7 a cylindrical housing 16 in which a rotationally symmetrical, overall also cylindrical filter element 18 is arranged. Of course, the invention is not limited to these geometries. The main catalyst 11 can be designed as a NOx storage catalyst in layer concepts.

Upstream of the precatalyst 7 is a first lambda probe 13 intended. Between the precatalyst according to the invention and particle filter 7 and the main catalyst 11 , which may be formed as a NOx storage catalyst, is a temperature sensor 15 intended. Downstream of the main catalyst 11 is a second lambda probe and / or NOx probe 17 intended. These probes 13 . 15 and 17 , are anyway in conventional exhaust aftertreatment devices with a precatalyst 7 and a main catalyst 11 , which is designed as a NOx storage catalyst present. Therefore, in the exhaust aftertreatment device according to the invention 3 , in which in the pre-catalyst 7 a particle filter is integrated, no additional sensors required.

In 2 is a longitudinal section through an embodiment of a filter element according to the invention 18 shown. The filter element 18 is inventively used as a combined pre-catalyst and particulate filter in the exhaust aftertreatment device 3 an operating according to the Otto process internal combustion engine 1 used with spark ignition.

The filter element 18 is produced as an extruded molded article of a porous ceramic material, such as cordierite. The filter element 18 will be in the direction of the arrows 9 flows through the exhaust gas, not shown. An entrance area has in 2 the reference number 22 while an exit surface in 2 the reference number 24 Has.

Parallel to a longitudinal axis 26 of the filter element 18 run several inlet channels 28 in alternation with outlet channels 30 , The entrance channels 28 are at the exit surface 24 locked. The sealing plugs are in 2 shown without reference number. In contrast, the exit channels 30 at the exit surface 24 open and in the area of the entrance area 22 locked.

The flow path of the unpurified exhaust gas thus leads into one of the inlet channels 28 and from there through a filter wall 34 in one of the exit channels 30 , This is exemplified by the arrows 32 shown.

In the embodiment according to 2 is both in the area of the entrance area 22 as well as in the area of the exit surface 24 a sealing ring 36 educated. The sealing ring is usually made of the same or at least a similar material as the filter element 18 and becomes insoluble with the filter element during sintering 18 connected. The sealing rings 36 facilitate the sealing of the filter element 18 in the case 16 ,

The combined filter element according to the invention 18 combines the functionality of a wallflow particulate filter with the functionality of a three-way catalyst. This can for example be done by the ceramic support of the filter element 18 is coated with correspondingly catalytically active substances, so that the filter element 18 simultaneously acts as a three-way catalyst.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10255308 [0001]

Claims (11)

Exhaust after-treatment device for a spark-ignition internal combustion engine comprising a pre-catalyst ( 7 ) and a main catalyst ( 11 ) or a main catalytic converter close to the engine ( 11 ), wherein the precatalyst ( 7 ) or the main catalyst close to the engine a housing ( 16 ), characterized in that in the housing ( 16 ) a particle filter ( 18 ) is integrated. Exhaust after-treatment device according to one of the preceding claims, characterized in that the precatalyst ( 7 ) and the particle filter ( 18 ) are arranged on a common carrier. Exhaust after-treatment device according to claim 2, characterized in that the support of the precatalyst ( 7 ) as a porous filter element ( 18 ) is formed, and that the filter element ( 18 ) is coated with catalytically active substances. Exhaust after-treatment device according to one of the preceding claims, characterized in that the particulate filter ( 18 ) is made of a ceramic material. Filter element according to one of the preceding claims, characterized in that the particle filter ( 18 ) of aluminum-magnesium silicate, preferably cordierite, titanium dioxide (TiO 2), silicon carbide (SiC) and / or aluminum titanate. Exhaust after-treatment device according to claim 2 or 3, characterized in that the particulate filter ( 18 ) is made of a metallic material, in particular a metal fabric. Exhaust after-treatment device according to one of the preceding claims, characterized in that the main catalytic converter ( 11 ) is designed as a NOx storage catalyst. Exhaust after-treatment device according to one of the preceding claims, characterized in that the particulate filter ( 18 ) and the NOx storage catalyst ( 11 ) are arranged on a common carrier. Exhaust after-treatment device according to one of the preceding claims, characterized in that the exhaust gas aftertreatment device ( 3 ) a first lambda probe ( 13 ), a temperature sensor ( 17 ), a second lambda probe and / or a NOx sensor ( 17 ). Exhaust after-treatment device according to one of the preceding claims, characterized in that it is intended for use on an internal combustion engine ( 1 ) with direct injection (BDE) and / or intake manifold injection (SRE). Process for the exhaust aftertreatment of the exhaust gas a Internal combustion engine with spark ignition, in which the exhaust gas a pre-catalyst and a main catalyst or a near-engine Main catalyst flows through, wherein the precatalyst or the main engine catalyst near a housing, characterized in that the exhaust gas also in the housing flows through integrated particle filter.