Particulate filter for an internal combustion engine and method for producing such a particulate filter

Abstract

A particulate filter for exhaust-gas aftertreatment in an internal combustion engine has a housing on which an inlet and an outlet are configured on opposite ends. The particulate filter also has a filter element arranged in the housing, said filter element having essentially parallel filter channels that are each alternatingly closed on the inlet side or on the outlet side by a closure in order to prevent gas from passing directly through the filter element. In this context, the filter channels can be divided into a first group of filter channels which are closed on the outlet side by a closure, and into a second group of filter channels which are closed on the inlet side by a gas-tight closure. The filter channels of the second group are additionally closed on the outlet side by a high-porosity closure in order to improve the cleaning effect of the particulate filter.

Claims

1. A method for the production of a particulate filter for an internal combustion engine, comprising: arranging a filter element in a housing of the particulate filter, configuring several first filter channels in the filter element, wherein each of which is closed on an outlet side by a low-porosity closure, configuring several second filter channels in the filter element, wherein each is closed on an inlet side by an impermeable closure, and separating the first filter channels and the second filter channels from each other by a filter wall, whereby at least some of the second filter channels are closed on the outlet side by high-porosity closures, and whereby the ratio of the permeabilities between the low-porosity closures and the high-porosity closures amounts to at least one to five.

2. The method for the production of a particulate filter according to claim 1, wherein the high-porosity closures are pressed and/or glued into the filter element.

3. The method for the production of a particulate filter according to claim 1, wherein the high-porosity closures are integrally bonded to the filter element or are configured on the filter element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained below on the basis of embodiments with reference to the accompanying drawings. In this context, identical components or components having the same function are provided with the same reference numerals. The following is shown:

(2) FIG. 1 is an internal combustion engine having an exhaust gas system in which a particulate filter according to the invention has been installed;

(3) FIG. 2 is an embodiment of a particulate filter according to the invention, in a simplified sectional view; and

(4) FIG. 3 is another embodiment of a particulate filter according to the invention, in a schematic sectional view.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows an externally ignited internal combustion engine 10 for a motor vehicle. The internal combustion engine 10 is preferably configured as a gasoline engine that is externally ignited by means of spark plugs 16. The internal combustion engine 10 has at least one combustion chamber 12, preferably several combustion chambers 12 as shown in FIG. 1, into which fuel can be injected by means of a fuel injector 14. The exhaust 18 of the internal combustion engine 10 is connected to an exhaust gas system 20. The exhaust gas system 20 comprises an exhaust gas channel 22 in which a turbine 26 of an exhaust gas turbocharger 24 is arranged in the direction in which exhaust gas flows through the exhaust gas channel 22 downstream from the exhaust 18. Downstream from the turbine 26, there is a three-way catalytic converter 28 in the exhaust gas channel 22, and further downstream, there is a particulate filter 30, especially a gasoline engine particulate filter 70.

(6) As an alternative, the particulate filter 30 can also be arranged as the first component of the exhaust-gas aftertreatment system downstream from the turbine 26 and in this embodiment, it is preferably configured with a catalytically active coating 62, especially with a three-way catalytically active coating 64, as a so-called four-way catalytic converter 32. In the case of a diesel engine, the catalytically active coating 62 of the particulate filter 30 is preferably configured as a coating 66 for the selective catalytic reduction of nitrogen oxides (SCR coating).

(7) A particulate filter 30 according to the invention for such an exhaust gas system 20 is shown in FIG. 2. The particulate filter 30 has a housing 34 which, as seen in the flow direction of the exhaust gas, has an inlet 40 on the front end, and an outlet 42 on the opposite end. A filter element 60 in which several essentially parallel filter channels 46, 48 are formed is arranged in the housing 34 of the particulate filter 30. The filter channels 46, 48 can be divided into first filter channels 46 and second filter channels 48. The first filter channels 46 are closed on the outlet side by a gas-impermeable closure 50, whereas the second filter channels 48 are closed by a gas-impermeable closure 50, especially a plug 56, on the inlet side, and by a high-porosity closure 54 on the outlet side. The first filter channels 46 and the second filter channels 48 are each configured like a honeycomb, whereby in each case, a first filter channel 46 and a second filter channel 48 are arranged next to each other and they separated from each other by a gas-permeable filter wall 44. As an alternative to a honeycomb-like configuration of the filter channels 46, 48, tubular filter channels 46, 48 are provided which likewise allow the filter element 60 to have a compact design.

(8) During operation of the particulate filter 30, the exhaust gas of the internal combustion engine 10 flows through the exhaust gas channel 22 and through the inlet 40 into the particulate filter 30. In this process, the exhaust gas flows through the first filter channels 46 into the filter element 60, exits from there through the filter wall 44 and flows through the second filter channel 48 towards the outlet 42 of the particulate filter 30. In this process, soot particles are deposited on the filter wall 44. Due to the deposition of the particles and due to the ash formed from the soot particles during the regeneration of the particulate filter 30, a deposit layer 58 is formed on the filter walls 44 and this layer enhances the filtering effect of the particulate filter 30.

(9) FIG. 3 shows another embodiment of a particulate filter 30 according to the invention. The particulate filter 30 has a housing 34 which, as seen in the flow direction of the exhaust gas, has an inlet 40 at the front end, and an outlet 42 on the opposite end. A filter element 60 in which several essentially parallel filter channels 46, 48 are formed is arranged in the housing 34 of the particulate filter 30. The filter channels 46, 48 can be divided into first filter channels 46 and second filter channels 48. The first filter channels 46 are closed on the outlet side by a low-porosity closure 50, especially a plug 56, whereas the second filter channels 48 are closed by a gas-impermeable closure 50, especially a plug 56, on the inlet side and by a high-porosity closure 54 on the outlet side. The first filter channels 46 and the second filter channels 48 are each configured in the form of honeycombs or tubes, whereby in each case, a first filter channel 46 and a second filter channel 48 are arranged next to each other, and they are separated from each other by a gas-permeable filter wall 44. Owing to the low-porosity closure of the first filter channels, a small percentage of the exhaust gas stream can flow through the filter element 60 without flowing through a filter wall 44. This can at least partially compensate for the exhaust-gas counter-pressure of the particulate filter 30 and for the familiar disadvantages associated with this, especially elevated fuel consumption and/or rough running of the internal combustion engine 10. In this embodiment as well, the main exhaust gas stream leaves the first group of filter channels 46 through the filter wall 44 and enters the second filter channels 48. In this context, it is provided that the porosity of the high-porosity outlet-side closures 54 of the second filter channels 48 is configured to be at least five times higher than the porosity of the low-porosity closures 52 of the first filter channels 46. This ensures that the flow resistance of the first filter channels 46 through the filter wall 44 and through the high-porosity closures 54 on the outlet side is less than the flow resistance through the first filter channels 46 and the low-porosity closures 52 on the outlet side, so that the main exhaust gas stream, preferably at least 80% of the exhaust gas volume, especially preferably at least 90% of the exhaust gas volume, can flow through the filter walls 44 of the particulate filter 30, and the soot particles contained in the exhaust gas of the internal combustion engine 10 can be deposited on these filter walls 44. By means of a particulate filter 30 according to the invention, the number of particles of as well as the particle concentration of a direct injection gasoline engine can be significantly reduced, thus diminishing the environmental impact.

LIST OF REFERENCE NUMERALS

(10) 10 internal combustion engine 12 combustion chamber 14 fuel injector 16 spark plug 18 exhaust 20 exhaust gas system 22 exhaust gas channel 24 exhaust gas turbocharger 26 turbine 28 three-way catalytic converter 30 particulate filter 32 four-way catalytic converter 34 housing 36 honeycombs 38 tubes 40 inlet 42 outlet 44 filter wall 46 first filter channel 48 second filter channel 50 impermeable closure 52 low-porosity closure 54 high-porosity closure 56 plug 58 deposited layer 60 filter element 62 catalytically active coating 64 three-way catalytically active coating 66 coating for the selective catalytic reduction of nitrogen oxides 68 diesel particulate filter 70 gasoline particulate filter P.sub.K particle concentration P.sub.N number of particles