JP2017101642A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control containing an electric heating type catalyst, which can secure insulation property and be manufactured easily.SOLUTION: An exhaust emission control device 10 includes an outer cylinder 11 storing an electric heating type catalyst thereinside, the outer cylinder 11 including a first electrode chamber 12a and a second electrode chamber 12b configured to supply power to the electric heating type catalyst stored thereinside. The second electrode chamber 12b is positioned above the first electrode chamber 12a in a state of being arranged in an exhaust passage of an internal combustion engine, and the second electrode chamber 12b comprises a volume part and a lid part covering an opening part of the volume part, a temperature sensor is not arranged in the first electrode chamber 12a, and on an inner surface, opposite to the electric heating type catalyst, of the lid part of the second electrode chamber 12b, a planar temperature sensor is disposed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust emission control device for purifying exhaust gas of an internal combustion engine.

  As a catalyst disposed in an exhaust passage of an in-vehicle internal combustion engine, an electric heating catalyst (hereinafter referred to as EHC) that can be preheated by an in-vehicle power source has been developed.

  When using EHC, it is necessary to be able to detect the temperature of EHC. For this reason, in order to detect the temperature of the EHC, it has been proposed to measure the gas temperature in the electrode chamber, which is a part where the power is introduced to the EHC, with an exhaust temperature sensor (temperature sensor).

Japanese Patent No. 5287990

  As described above, when the gas temperature in the electrode chamber is measured by the temperature sensor, the temperature sensor is also required to ensure insulation. Further, when the gas temperature in the electrode chamber is measured by the temperature sensor, it is necessary to fix the temperature sensor at a desired position in the electrode chamber. Therefore, the exhaust purification device that measures the gas temperature in the electrode chamber with the temperature sensor may deteriorate the workability during manufacture (assembly).

  The present invention has been made in view of the above problems, and provides an exhaust emission control device including an electrically heated catalyst, which has an insulating property and can be easily manufactured. For the purpose.

  In order to solve the above problems, an exhaust emission control device for purifying exhaust gas of an internal combustion engine according to the present invention has a first electrode and a second electrode, and is energized through the first electrode and the second electrode. An electrically heated catalyst that generates heat, and an outer cylinder that is disposed in an exhaust passage of the internal combustion engine, in which the electrically heated catalyst is housed, and the electrically heated catalyst that is housed in the electrically heated catalyst. A first electrode chamber having an inner surface facing the first electrode, and an outer cylinder having a second electrode chamber having an inner surface facing the second electrode of the electrically heated catalyst housed therein. The second electrode chamber is located above the first electrode chamber, and the second electrode chamber has a lid portion having the inner surface, and the outer cylinder is disposed in the exhaust passage. Formed by a volume portion having an opening covered by the lid portion, A pole not disposed is a temperature sensor in the room, the structure in which the plate-like temperature sensor of the said inner surface of said lid portion of the second electrode chamber is disposed.

That is, in the exhaust purification apparatus of the present invention, since the temperature sensor is disposed in the second electrode chamber, if the correspondence between the temperature measured by the temperature sensor and the EHC temperature is obtained in advance, the temperature sensor The EHC temperature can be estimated from the measured temperature and the corresponding relationship. The temperature sensor in the second electrode chamber is a flat plate-shaped temperature sensor disposed on the inner surface of the lid, which is a component of the second electrode chamber, facing the second electrode. Therefore, at the time of manufacturing (assembling) the exhaust purification apparatus of the present invention, the temperature sensor can be insulated only by assembling the lid portion on which the flat plate-like temperature sensor is disposed on the inner surface with the volume portion of the second electrode chamber. Can be arranged at a position where the Therefore, if the configuration of the exhaust emission control device of the present invention is adopted, an exhaust emission control device that ensures insulation can be easily manufactured.

  Furthermore, the exhaust emission control device of the present invention includes a first electrode chamber positioned below the second electrode chamber. When condensed water is generated by cooling the exhaust gas and the condensed water flows into the electrode chamber, the condensed water may flow into the first electrode chamber located below the second electrode chamber. Here, in the exhaust emission control device of the present invention, the temperature sensor is disposed in the second electrode chamber, but is not disposed in the first electrode chamber. Therefore, according to the exhaust gas purification apparatus of the present invention, the temperature can be measured while suppressing the formation of a leakage path via the temperature sensor due to the condensed water. Moreover, since the temperature sensor is provided only in one of the two electrode chambers, the exhaust purification device can be manufactured at low cost.

  According to the present invention, it is possible to provide an exhaust emission control device that ensures insulation and can be easily manufactured.

FIG. 1 is an external view of an exhaust gas purification apparatus according to an embodiment of the present invention as viewed from the exhaust inlet side. 2 is an external view of the exhaust emission control device according to the embodiment as viewed from the right side in FIG. 3 is a cross-sectional view of the exhaust purification apparatus according to the embodiment, taken along line AA in FIG. 4 is a cross-sectional view of the exhaust emission control device according to the embodiment, taken along line BB in FIG. FIG. 5 is an explanatory diagram of a modified example of the second electrode chamber. FIG. 6 is an explanatory diagram of a modified example of the exhaust emission control device according to the embodiment.

  Hereinafter, modes for carrying out the present invention will be described based on examples. It should be noted that the configuration of the exhaust gas purification apparatus according to the embodiments described below is not intended to limit the scope of the present invention only to those unless otherwise specified.

  FIG. 1 shows an external view of an exhaust purification apparatus 10 according to an embodiment of the present invention as seen from the exhaust inlet side, and FIG. 2 shows an external view of the exhaust purification apparatus 10 as seen from the right side in FIG. Show. 3 shows a cross-sectional view of the exhaust purification device 10 taken along line AA in FIG. 1, and FIG. 4 shows a cross-sectional view of the exhaust purification device 10 taken along line BB in FIG.

  Hereinafter, the exhaust emission control device 10 according to the present embodiment will be described with reference to these drawings. In the following description, “upper and lower” means the upper and lower sides in a state where the exhaust purification device 10 is disposed in the exhaust passage of the in-vehicle internal combustion engine. The exhaust purification device 10 is usually an internal combustion engine (diesel engine or gasoline) mounted on a hybrid vehicle equipped with a traveling motor or a vehicle not equipped with a traveling motor, with the upper side in FIG. It is arranged in the exhaust passage of the engine).

  As shown in FIGS. 1 to 3, the exhaust purification device 10 includes a cylindrical outer cylinder 11. As schematically shown in FIG. 3, the outer cylinder 11 is composed of a plurality of members. In the outer cylinder 11, the electrically heated catalyst (EHC) 20 and the downstream catalyst 25 are accommodated with a holding mat 26 sandwiched between the outer peripheral surface of each catalyst and the inner surface of the outer cylinder 11. ing.

  The EHC 20 is a catalyst in which an exhaust purification catalyst is supported on a conductive carrier. The carrier of the EHC 20 has a plurality of passages extending in the exhaust flow direction and having a honeycomb cross-sectional shape perpendicular to the exhaust flow direction. An example of the constituent material of the EHC 20 carrier is SiC. The exhaust purification catalyst carried on the carrier of the EHC 20 and the exhaust purification catalyst carried on the carrier of the downstream catalyst 25 should be selected according to the use of the exhaust purification device 10, but the exhaust purification catalyst carried on each carrier. Examples thereof include an oxidation catalyst, a NOx storage reduction catalyst, a selective reduction NOx catalyst, and a three-way catalyst.

  As shown in FIGS. 3 and 4, the cylindrical wall of the outer cylinder 11 is provided with a first opening 17 a and a second opening 17 b. Further, as shown in FIG. 3, a current is passed through the EHC 20 (the carrier used in the EHC 20) to the portion of the side surface of the EHC 20 that faces the first opening 17a when accommodated in the outer cylinder 11. Therefore, a first electrode 21a is formed. Further, as shown in FIG. 4, a second electrode 21 b for allowing a current to flow through the EHC 20 is formed on a portion of the side surface of the EHC 20 that faces the second opening 17 b when accommodated in the outer cylinder 11. ing.

  The outer cylinder 11 includes a first electrode chamber 12a (FIG. 3) that covers the first opening 17a and a second electrode chamber 12b (FIG. 4) that covers the second opening 17b. As shown in FIG. 1, the outer cylinder 11 is configured such that the second electrode chamber 12b is positioned above the first electrode chamber 12a when disposed in the exhaust passage.

  More specifically, when the outer cylinder 11 (exhaust gas purification device 10) is disposed in the exhaust passage, the lower end of the second opening 17b is located above the lower end of the first opening 17a. A first opening 17a and a second opening 17b are formed so as to be positioned. As described above, the first electrode chamber 12a and the second electrode chamber 12b cover the first opening 17a and the second opening 17b, respectively. Therefore, when the outer cylinder 11 (exhaust gas purification device 10) is disposed in the exhaust passage, the second electrode chamber 12b is positioned above the first electrode chamber 12a.

  The configuration shown in FIG. 3 is adopted for the first electrode chamber 12a located below the second electrode chamber 12b.

  That is, the first electrode chamber 12 a is formed by a rectangular tubular volume 31 fixed to the opening 17 a of the outer cylinder 11 and a lid 32 a that covers the opening of the volume 31. A cable terminal 41 connected to the power cable 40 is inserted into the volume portion 31 of the first electrode chamber 12a in such a manner that it is insulated from the volume portion 31 by an insulator 45. The cable terminal 41 is connected to the electrode 21a of the EHC 20 and the metal foil 43 in the first electrode chamber 12a.

  On the other hand, the configuration shown in FIG. 4 is adopted for the second electrode chamber 12b located above the first electrode chamber 12a.

  That is, the second electrode chamber 12 b is formed by a rectangular tubular volume 31 fixed to the opening 17 b of the outer cylinder 11 and a lid 32 b that covers the opening of the volume 31.

  The volume portion 31 of the second electrode chamber 12b is a member having the same shape as the volume portion 31 of the first electrode chamber 12a. The lid portion 32b is a member that is configured by the member 32 'and the member 15 and has substantially the same shape as the lid portion 32a. As shown in the drawing, a flat plate-shaped temperature sensor 16 is disposed on the inner surface of the lid portion 32b (the surface facing the electrode 21b side of the member 15 constituting the lid portion 32b).

More specifically, the member 32 ′ of the lid portion 32 b is provided with a through hole for inserting and fixing the member 15 in a portion of the lid portion 32 a (FIG. 3) facing the electrode 21 a of the EHC 20. ing. The member 15 is a member to which the temperature sensor 16 is attached in advance. And the part which consists of the cover part 32b and the temperature sensor 16 of the 2nd electrode chamber 12b is comprised by inserting and fixing the member 15 to which the temperature sensor 16 is previously attached to the through-hole of member 32 '. Yes.

  The lid portion 32b of the second electrode chamber 12b may be anything as long as the flat temperature sensor 16 can be disposed on the inner surface of the EHC 20 facing the electrode 21b. Therefore, a lid 32b having a different configuration from that shown in FIG. 4 may be employed. For example, the lid portion 32b as shown in FIG. 5, that is, the lid portion 32b having the same shape as the lid portion 32a, which is processed so that the signal line of the temperature sensor 16 can be drawn from the side wall thereof is adopted. You may do it. In addition, the temperature sensor 16 disposed on the inner surface of the lid portion 32b is a flat plate temperature sensor (heat flow) that detects radiant heat even if a thermocouple or a resistance temperature detector is embedded in a flat plate high heat conductor. A bundle sensor).

  The second electrode chamber 12b of the exhaust gas purification apparatus 10 adopts the above-described configuration, and the distance between the temperature sensor 16 and the cable terminal 41 is a distance necessary for ensuring insulation (for example, 8 mm). Thus, the size of each part is determined and manufactured.

  Here, the control system of the exhaust emission control device 10 will be briefly described.

  In the control system of the exhaust gas purification apparatus 10, correspondence information indicating a correspondence relationship between the temperature measured by the temperature sensor 16 and the temperature of the EHC 20 obtained by experiments or the like is set. Then, the control system estimates the temperature of the EHC 20 from the temperature measured by the temperature sensor 16 and the corresponding relationship information.

  As described above, in the exhaust purification apparatus 10 according to the present embodiment, the flat plate temperature sensor 16 is disposed on the inner surface of the lid portion 32b of the second electrode chamber 12b facing the second electrode 21b of the EHC 20. Has been. The temperature measured by the temperature sensor 16 disposed at such a position is hardly affected by the operating state of the internal combustion engine (whether or not the exhaust gas flows through the exhaust passage). Therefore, the temperature of the EHC 20 can be accurately estimated from the temperature measured by the temperature sensor 16 and the correspondence information. Further, if the flat plate-shaped temperature sensor 16 is disposed on the inner surface of the lid portion 32b facing the second electrode 21b of the EHC 20, the insulating property of the temperature sensor 16 can be obtained simply by assembling the lid portion 32b to the volume portion 31. Can be secured. Therefore, if the above configuration is adopted, the exhaust emission control device 10 in which insulation is ensured can be easily manufactured.

  Further, in the exhaust gas purification apparatus provided with EHC, condensed water may be generated by cooling the exhaust gas, and the condensed water may flow into the electrode chamber. However, the exhaust gas purification apparatus 10 is positioned below the second electrode chamber 12b. The first electrode chamber 12a is provided. Therefore, in the exhaust gas purification device 10, when condensed water is generated by cooling the exhaust gas and the condensed water flows into any one of the electrode chambers 12 via the holding mat 26 or the like, the condensed water is usually in the second electrode chamber. It flows into the first electrode chamber 12a located below 12b. The first electrode chamber 12a is not provided with a temperature sensor. Therefore, according to the exhaust gas purification apparatus 10, it is possible to estimate the temperature of the EHC 20 while suppressing the formation of a leakage path via the temperature sensor due to the condensed water. Moreover, since the temperature sensor is provided only in one of the two electrode chambers 12, the exhaust purification device 10 can be manufactured at low cost.

<Modification>
The above-described exhaust purification device 10 can be variously modified. For example, the second electrode chamber 12b of the exhaust emission control device 10 extends obliquely upward (see FIG. 1), but the second electrode chamber 12b is even positioned above the first electrode chamber 12a. For example, it may extend obliquely downward. Therefore, the exhaust purification apparatus 10 is, for example, an apparatus as shown in FIG. 6, that is, the first electrode chamber 12a and the second electrode chamber 12b both extend obliquely downward, and the second electrode chamber 12b It can deform | transform into the apparatus located above the 1st electrode chamber 12a.

DESCRIPTION OF SYMBOLS 10 Exhaust gas purification apparatus 11 Outer cylinder 12a 1st electrode chamber 12b 2nd electrode chamber 16 Temperature sensor 17a 1st opening part 17b 2nd opening part 20 Electric heating type catalyst 21a 1st electrode 21b 2nd electrode 25 Downstream side catalyst 26 Holding mat 31 Volume part 32a, 32b Lid part 40 Power cable 41 Cable terminal 43 Metal foil 45 Insulator

Claims (1)

In an exhaust emission control device for purifying exhaust gas from an internal combustion engine,
An electrically heated catalyst that has a first electrode and a second electrode, and generates heat when energized through the first electrode and the second electrode;
An outer cylinder that is disposed in an exhaust passage of the internal combustion engine, in which the electrically heated catalyst is accommodated, and has an inner surface that faces the first electrode of the electrically heated catalyst that is accommodated in the interior. An outer cylinder including a first electrode chamber, and a second electrode chamber having an inner surface facing the second electrode of the electrically heated catalyst housed therein;
Including
With the outer cylinder disposed in the exhaust passage, the second electrode chamber is located above the first electrode chamber,
The second electrode chamber is formed by a lid portion having the inner surface and a volume portion having an opening covered by the lid portion,
An exhaust gas purification apparatus, wherein no temperature sensor is arranged in the first electrode chamber, and a flat plate temperature sensor is arranged on the inner surface of the lid portion of the second electrode chamber.