KR20020068049A - Device for the exhaust treatment in an internal combustion engine - Google Patents

Abstract

At least one catalytic converter chamber has one or a plurality of heater plugs 30 and all of the heater plugs 30 have a heater 44, which is the catalyst after the exhaust gas first flows through the heater or heaters. In the exhaust gas treatment apparatus of an internal combustion engine comprising one or more catalytic converter chambers arranged to pass through the converter 20, in which ignition of exhaust gases containing combustible components by heating of the heater 44 can be ensured. The apparatus relates to a device in which the heater 44 has an outer ceramic layer facing the catalytic converter chamber 13.

Description

Device for the exhaust treatment in an internal combustion engine}

German Patent Publication No. 39 39 068 discloses such a device having a catalytic converter in which the catalytic converter is heated by one or a plurality of heater plugs protruding from the catalytic converter. In WO 97/25525 also a heater plug mounted in front of the catalytic converter waiting room is used for heating the catalytic converter waiting room and for ignition of the combustible mixture.

The amount of heat dissipated during ignition of the combustible mixture in the exhaust gas pipe (mixture ignition is also referred to as exhaust gas subsequent combustion) is known in German Patent Publication No. 44 00 260 for the principle used to heat the catalytic converter device for exhaust gas treatment. It is. Thus, rapid heating of the catalytic converter reaches the operating temperature based on the amount of heat dissipated. The heat supply of the catalytic converter is carried out over a particularly short time after the start of the internal combustion engine. This is because most catalytic converters can no longer withstand the minimum operating temperature. Only at a minimum operating temperature of about 300 ° C. an effective reduction of contaminated components of the exhaust gas can be ensured.

The heater plug used in the exhaust gas treatment device according to the prior art has a heating element comprising a metallic sleeve closed to the catalytic converter waiting room, which is located externally for the exhaust gas subsequent combustion, the heat supply of the heater being internal Is made by a heating wire in the. Also provided is a ceramic powder inside the metallic sleeve, which provides heat conduction to the metallic sleeve on the one hand by the heating wire and on the other hand holds the wire in place. Seals made mainly of elastomer are used to seal the metallic sleeves that are open away from the catalytic converter waiting room, which seals the ceramic powder or heating wire in a vacuum. The sealing portion used according to the prior art is unstable at a temperature of about 220 ° C. or higher and thus cannot perform the sealing function in the above temperature range. In operation of the internal combustion engine, the heater temperature in the assembly position and the sealing position of the exhaust gas pipe is in the range of 500 ° C to 600 ° C. Therefore, the seal of the heater used according to the prior art in the exhaust gas treating apparatus is not suitable.

The present invention relates to an exhaust gas treating apparatus according to the preamble of the independent claim. The device is in particular mounted on an internal combustion engine.

1 is a schematic diagram of an exhaust gas treating apparatus of an internal combustion engine according to the present invention;

2 and 3 show an embodiment of the heater plug of the exhaust gas treating apparatus according to the present invention.

4 and 5 show an embodiment of a heater of an exhaust gas treatment device according to the invention on a longitudinal cross section.

An exhaust gas treatment device according to the invention comprising the features of the independent claims has the advantage that the heater closure is no longer necessary. In addition, the heating member of the exhaust gas treating apparatus according to the present invention has stability at high temperatures and with respect to the reactive gas.

The measures set out in the dependent claims enable the implementation and improvement of the subject matter set out in the independent claims. It is desirable to form a heating member consisting of two interconnected electrically insulating ceramic layers and one insulating ceramic layer. Because it is formed in a simple structure. In connection with the coefficient of thermal expansion of various components of the heating element, the formation of the heating element preferably consists of an electrically insulating and insulating ceramic layer. This is because the coefficient of thermal expansion can be optimally adjusted by variations in the composition of the layer. Therefore, damage to the heating member during heat circulation is prevented. The structure can be implemented in U-shaped and cylindrical on the conductive ceramic side. In addition, the heating member by the metallic heating wire located therein is preferably formed to be surrounded by a ceramic matrix. This is because the above simple implementation of the ceramic layer is possible outside the heating element. Embodiments of the invention are shown in the drawings and are described in detail below.

FIG. 1 schematically shows an exhaust gas treating apparatus in which exhaust gas generated from one or a plurality of combustion chambers 5 moves to an exhaust gas pipe 7 as a longitudinal section. The path of the exhaust gas is indicated by the arrow. The exhaust gas first passes through the exhaust gas pipe 10 and then reaches the catalytic converter chamber 13, which has a larger cross section than the exhaust gas pipe 10. The catalytic converter chamber 13 includes a catalytic converter waiting room 15 and a catalytic converter 20. The catalytic converter chamber 15 is equipped with one or more heater plugs 30. The heater plug has a connecting connector 35 and a supply pipe 40. The heater plug may also be disposed in a portion of the catalytic converter waiting room 15, as shown, in which the cross section of the exhaust gas conduit extends from the exhaust gas pipe 10 to the catalytic converter chamber 13 or the heater. The plug may be arranged in a portion of the catalytic converter waiting room 15 having a cross section of the catalytic converter. This point corresponds to reference numeral 41. In addition, a supply pipe for auxiliary air is disposed in the exhaust gas pipe 41. The precatalyst converter is arranged in the exhaust gas pipe in front of the supply pipe in the exhaust gas pipe 7. It is also possible to arrange the flow regulator in the catalytic converter waiting room 15 in front of the heater plug 30. It is also possible to mount one or more oxygen sensors on the exhaust gas pipe 7. The oxygen sensor is generally formed with a lambda probe.

The exhaust gas flows from the combustion chamber 5 through the exhaust gas pipe 7 in the direction of the arrow. Therefore, it first passes through the exhaust gas pipe 10. Auxiliary air is supplied to the exhaust gases there through a supply pipe for auxiliary air. Therefore, the exhaust gas mixed with the auxiliary air passes through the catalytic converter waiting room 15, and the amount of heat is released by the heater plug 30 at a specific time in the catalytic converter waiting room. The exhaust gas then enters the catalytic converter 20. In the catalytic converter 20, which is usually formed of a three-stage catalytic converter, the CO, NOx and HC components of the exhaust gas react with the precipitates of the catalytic carrier which act catalytically. The catalytic converter 20 must have a temperature exceeding 300 ° C. in order to be able to react with the catalyst. This temperature is called the conversion limit. The catalytic converter 20 has not yet reached the conversion temperature at the start of the internal combustion engine. That is why it is necessary to heat the tentative converter. Heating of the catalytic converter is a simple way of heating the catalytic converter by the so-called exhaust gas combustion already mentioned at the beginning of the present description, and a high energy release is achieved. This makes it possible to heat the catalytic converter very quickly. The heating takes place during cycles up to several minutes after the start of the internal combustion engine and during operation of the internal combustion engine, for example, by a temperature sensor confirming that the temperature of the catalytic converter is reduced below the change limit.

The oily exhaust gas is provided under the influence of the injected fuel amount and / or the firing angle. The exhaust gas is mixed with the auxiliary air through the auxiliary air pipe 43 to produce a combustible exhaust gas. Ignition of the exhaust gas is provided using the amount of heat provided by the heater plug 30 of the catalytic converter waiting room 13. The amount of heat generated through the exothermic reaction by combustion of the exhaust gas is used for heating the catalytic converter 20. The exhaust gas combustion is carried out immediately after the start of the internal combustion engine or until a few minutes if it is confirmed that it is below the conversion limit. The heater plug is operated in this cycle to ensure combustion. The electrical energy required for heating to the heater plug 30 is provided through the connector 30 and the supply pipe 40. The energy is obtained from a power supply of an internal combustion engine, not shown.

The heater plug 30 is provided with a heater 44 and the heater has an outer layer of ceramic components facing the catalytic converter waiting room 15 in the exhaust gas treatment apparatus according to the invention. It is possible to implement a plug 30 of an unsealed heater that does not operate by the temperature of the heater plug. The heater plug of the exhaust gas treatment device according to the invention is thus used for cooling without additional measures to assist in exhaust gas subsequent combustion. In addition, the heater plug 30 has a high temperature and high stability to the reaction gas.

Figure 2 shows schematically in longitudinal section an embodiment of a heater plug for a catalytic converter waiting room of an exhaust gas treatment apparatus according to the present invention. The heater plug 30 has a metallic housing 45. The terminal pillar 50 is disposed in the central cylindrical hole of the housing 45, and the pillar is fixed by the sealing member 55. The sealing member 55 also seals the end portion away from the catalytic converter waiting room of the heater plug. In a preferred embodiment, a connecting member 60, which can be formed of an elastic member, mainly a contact spring or powder packing, is arranged towards the catalytic converter waiting room. The cylindrical central hole of the housing is also provided with a heater 44 towards the catalytic converter waiting room behind the connecting member. The heater 44 protrudes through the end of the housing 45 into the catalytic converter waiting room 15. Because of the electrical resistance present in the heater, the catalytic converter 20 is heated by the heating of the heater plug 44 and the exhaust gas ignited by it.

The heater 44 consists of a first electrically insulating layer 90 and a second electrically insulating layer 95. Both electrically insulating layers composed of electrically insulating ceramics are likewise separated by an insulating layer 97 composed of ceramic material. At the edge of the catalytic converter waiting room side of the heater 44, the first electrically insulating layer 90 and the second electrically insulating side 95 are connected to each other in the region 100. The region 100 is also made of ceramic material. The electrical contact extends through the connecting member 60 and the first electrically insulating layer 90, the connecting region 100 and the second electrically insulating layer 95 to the housing 45. Heating of the heater 44 is effected by the resistance of the electrically insulating layers 90 and 100 made of ceramic material. The heater is formed of only ceramics, ie the layer facing the catalytic converter waiting room consists of a solid ceramic material. Thus, there is no other metallic material inside the heater that must be sealed against oxygen. Thus, the sealing itself of the heater is not essential and the elastomeric seal need not be used for the heater. In addition, the ceramic material of the heater has high stability against high temperature and reaction gas.

The configuration of the heater 44 is preferably made only of a ceramic material. This is because simple manufacture is possible and the coefficient of thermal expansion of the material is adjustable by the combination deformation of various ceramic materials.

3 schematically shows, in cross section, a heater plug 30 arranged in a catalytic converter waiting room 15 of an exhaust gas treatment apparatus according to the invention. Since the configuration is similar to that of the heater plug in FIG. 2 up to the heater 44, it is not detailed here for this part of the heater plug. Like numbers refer to like parts.

In the heater 44 shown in FIG. 3, a metallic heating wire is embedded in the ceramic matrix 70. The electric power supply of the heater 44 is made by the supply pipe 40 and the connector 35 (the latter is shown in FIG. 1). The connector 35 is in an electrical contact comprising a terminal post 50 and a connecting member 60. The connecting member 60 again has an electrical contact comprising a heating wire. The heating wire is extended in a U shape by a heater as shown in FIG. It also consists of multiple, interconnected bundles of heating wires having different resistivity and resistance temperature characteristics. The heating wire is also inside an electrical contact comprising a grounded housing 45. The heater 44 is disposed in the cylindrical central hole of the metal tube with a part of the end far from the catalytic converter waiting room of the heater, and the metal tube is again disposed in the central hole of the housing 45. The electrical contact, which also comprises the connector 35 of the heating wire, is in another embodiment via at least one supply pipe extending laterally in the central hole of the housing 45 instead of the connecting member 60 and the terminal pillar 50. Can be done.

In the heat exchanger for the catalytic converter waiting room of the exhaust gas treating apparatus according to the present invention, the formation method in which the outer layer of the heater facing the catalytic converter waiting room is composed of a ceramic material and a ceramic matrix 44 is an advantage. The metallic heating wire 75 is firmly clinked into a solid ceramic matrix 70 and therefore does not need to be used in the seal of the heater.

4 schematically shows various embodiments of the heater for the heater plug according to FIG. 2 in the catalytic converter waiting room of the exhaust gas treatment apparatus according to the invention. In Fig. 4a such a heater is shown in longitudinal section. The heater is formed similarly to the heater of FIG. 2 and is not described repeatedly, and like reference numerals denote like parts. In FIG. B the heater of the heater plug for the catalytic converter waiting room of the exhaust gas treating apparatus according to the invention is shown. The cross section should be located below the connection region 100 on the forward side of the catalytic converter waiting room. A first electrically insulating layer 90, a second electrically insulating layer 95 and an insulating layer 97 are shown. The cross section is formed in a rectangle. Another cross section of the heater 44 is shown in FIG. 4C. The cross section comprises the same parts as in FIG. 4B and is rounded in the form of a cross section. A similar cross section is shown in FIG. 4D, in which the cross section is a completely round face without rounded corners as in FIG. 4C. Another heater according to the invention is shown in FIG. 4E and the heater also has the same parts as in FIG. 4B. Here the total cross section of the heater has the shape of an ellipse. In each of Figs. 4B to 4E, it is possible to achieve shorter planes with greater or equal length. In addition, the elliptic shape of Figure 4e may be formed in a circular shape. The different cross sections shown in FIGS. 4b to 4e can optimally control the shape of the heater 44 in the conditions of the catalytic converter waiting room. Other cross sectional shapes of the heater 44 can also be envisioned.

5 shows another embodiment of a heater 44 for a catalytic converter in an exhaust gas treatment device according to the present invention. 5a schematically illustrates the longitudinal section by such a heater. The electrically insulating layer and the insulating layer are arranged in a cylindrical shape in the above embodiment. The first electrically insulating ceramic layer 90 forms an inner cylinder surrounding the electrically insulating ceramic layer 97 formed in the form of a pipe. The layer is again surrounded by a pipe in the form of an electrically insulating layer 95. The first electrically insulating layer 90 and the second electrically insulating layer 95, which are also made of ceramic material, are connected to each other in the corner region of the catalytic converter side of the heater 100. The structure of the heater plug is indicated in a cylindrical shape. In FIG. 5B the heater shown in FIG. 5A is shown in cross section. The cross section is located below the connection region 100. It can be seen that the first electrically insulating layer 90 is located inside and surrounded by the insulating layer 95 which is again surrounded by the electrically insulating layer 95. The embodiment is thus characterized by an external ceramic layer and is safe for the action of temperature and regeneration gas. In this embodiment, the heater 44 is composed of various solid ceramic layers and the layers are calcified from each other. Thus, in this embodiment, the interior of the heater 44 does not need to be sealed by a seal against oxygen. In figure 5c a similar cylindrical embodiment of the ceramic heater is shown in cross section as in figure 5b. FIG. 5C is distinguished from FIG. 5B in the form. The layers here have a rectangular cross section. Basically, however, the structure is consistent with the structure described in Figures 5a and 5b. The structure can be adjusted according to the production conditions and the conditions in the catalytic converter waiting room.

Claims (5)

At least one catalytic converter chamber has one or more heater plugs 30 and all of the heater plugs 30 have heaters 44, in which the exhaust gas first flows through the heaters or heaters, and then Apparatus for exhaust gas treatment of an internal combustion engine comprising one or more catalytic converter chambers arranged to pass through the catalytic converter 20, in which ignition of exhaust gases containing combustible components by heating of the heater 44 can be ensured. To The heater (44) having an outer ceramic layer facing the catalytic converter chamber. 2. The device according to claim 1, wherein the heater (44) has a heating wire (75) of metal located therein and the heating wire (75) is surrounded by a ceramic matrix (70). 2. The heater of claim 1, wherein the heater 44 comprises an electrically insulating ceramic layer 97 and first and second electrically insulating ceramic layers 90, 95, wherein the layers 90, 95 are insulating layers 97. And the first and second electrically insulating ceramic layers are connected to each other by electrically insulating ceramic regions (100) at the catalytic converter waiting room side end of the heater (44). 4. A device according to claim 3, wherein the combination of the first and second electrically insulating ceramic layers (90,95) and the connection of both electrically insulating layers (100) is embodied in a U shape. 4. An apparatus according to claim 3, wherein the combination of the first and second electrically insulating ceramic layers (90,95) and the connection of both electrically insulating layers (100) is embodied in a cylindrical shape.