WO2012120669A1 - 電気加熱式触媒 - Google Patents
電気加熱式触媒 Download PDFInfo
- Publication number
- WO2012120669A1 WO2012120669A1 PCT/JP2011/055542 JP2011055542W WO2012120669A1 WO 2012120669 A1 WO2012120669 A1 WO 2012120669A1 JP 2011055542 W JP2011055542 W JP 2011055542W WO 2012120669 A1 WO2012120669 A1 WO 2012120669A1
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- WIPO (PCT)
- Prior art keywords
- catalyst
- case
- support member
- insulating support
- inner tube
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
- F01N3/2013—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2839—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration
- F01N3/2853—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration using mats or gaskets between catalyst body and housing
- F01N3/2871—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration using mats or gaskets between catalyst body and housing the mats or gaskets having an additional, e.g. non-insulating or non-cushioning layer, a metal foil or an adhesive layer
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
- F01N3/2013—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means
- F01N3/2026—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using electric or magnetic heating means directly electrifying the catalyst substrate, i.e. heating the electrically conductive catalyst substrate by joule effect
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2839—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration
- F01N3/2853—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration using mats or gaskets between catalyst body and housing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2470/00—Structure or shape of gas passages, pipes or tubes
- F01N2470/24—Concentric tubes or tubes being concentric to housing, e.g. telescopically assembled
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2510/00—Surface coverings
- F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2510/00—Surface coverings
- F01N2510/10—Surface coverings for preventing carbon deposits, e.g. chromium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2530/00—Selection of materials for tubes, chambers or housings
- F01N2530/02—Corrosion resistive metals
- F01N2530/04—Steel alloys, e.g. stainless steel
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Definitions
- the present invention relates to an electrically heated catalyst provided in an exhaust passage of an internal combustion engine.
- an electrically heated catalyst (hereinafter referred to as EHC) in which the catalyst is heated by a heating element that generates heat when energized has been developed.
- an insulating support member that supports the heating element and insulates electricity is provided between a heating element that generates heat when energized and a case that accommodates the heating element.
- Patent Document 1 discloses a technique for providing an insulating mat between a carrier that generates heat when energized and a case that houses the carrier in EHC.
- EHC there is a case where an inner pipe is provided in order to suppress a short circuit between the heating element and the case due to condensed water that has entered (infiltrated) the insulating support member.
- the inner tube is a tubular member that is sandwiched by insulating support members so as to be positioned between the heating element and the case. Further, the inner pipe is formed with an electric insulating layer on the entire surface or is formed of an electric insulating material.
- the inner pipe When the inner pipe is provided in the EHC, the inner pipe is formed so as to protrude into the exhaust gas from the end face of the insulating support member.
- the inner pipe suppresses that the condensed water that has flowed through the inner wall surface of the case and reached the insulating support member reaches the heating element through the end face of the insulating support member. The Therefore, it is possible to suppress a short circuit between the heating element and the case due to the condensed water not only inside the insulating support member but also on the end face of the insulating support member.
- particulate matter (hereinafter referred to as PM) in the exhaust gas adheres to the protruding portion protruding from the end face of the insulating support member in the inner tube.
- PM particulate matter
- the present invention has been made in view of the above problems, and an object thereof is to suppress a short circuit between a heating element and a case in EHC.
- the present invention provides a catalyst having an oxidation function, except for a predetermined range in which at least an outer peripheral surface of the protruding portion protruding into the exhaust from the end surface of the insulating support member in the inner pipe is in contact with the end surface of the insulating support member. It is something to cover.
- the electrically heated catalyst (EHC) is A heating element that generates heat when energized and heats the catalyst by generating heat;
- An insulating support member provided between the heating element and the case and supporting the heating element and insulating electricity;
- a tubular member sandwiched between the insulating support members so as to be positioned between the heating element and the case, the end of which protrudes from the end surface of the insulating support member into the exhaust gas, and the entire surface
- An inner tube formed of an electric insulating material or an electric insulating material;
- a catalyst having an oxidation function that covers at least the outer peripheral surface of the protruding portion protruding into the exhaust gas from the end surface of the insulating support member in the inner pipe except for a predetermined range in contact with the end surface of the insulating support member; Is provided.
- the portion covered with the catalyst becomes porous, so that condensed water tends to stay in the portion. Accordingly, when the entire protruding portion of the inner pipe is covered with the catalyst, the heat generating body and the case are easily short-circuited by the accumulated condensed water.
- the flow rate of the exhaust is less on the outside of the inner tube than on the inside. Therefore, PM is less likely to deposit on the outer peripheral surface of the protruding portion of the inner tube than the inner peripheral surface of the protruding portion. Further, in the protruding portion of the inner tube, PM is less likely to deposit in a portion near the end surface of the insulating support member than in a portion away from the end surface of the insulating support member. Therefore, in the projecting portion of the inner tube, PM is hardly deposited in a portion near the end surface of the insulating support member on the outer peripheral surface.
- the outer peripheral surface of the protruding portion of the inner tube is covered with a catalyst having an oxidation function except for a predetermined range in contact with the end surface of the insulating support member. That is, the catalyst is not provided in the portion where the PM is most difficult to deposit in the protruding portion of the inner tube. Condensed water is unlikely to stay in a portion where the catalyst is not provided.
- the amount of the catalyst covering the downstream protruding portion of the inner pipe is set to the amount of the inner pipe.
- the amount may be smaller than the amount of catalyst covering the upstream protrusion. In this case, only the upstream protruding portion of the inner tube may be covered with the catalyst.
- the amount of PM in the exhaust gas flowing out from the EHC is smaller than the amount of PM in the exhaust gas flowing into the EHC. Therefore, the amount of PM adhering to the protrusion on the downstream side of the inner pipe is smaller than the amount of PM adhering to the protrusion on the upstream side of the inner pipe. Further, the temperature of the exhaust gas flowing out from the EHC is higher than the temperature of the exhaust gas flowing into the EHC. Therefore, the temperature of the protrusion on the downstream side of the inner pipe is higher than the temperature of the protrusion on the upstream side of the inner pipe. Accordingly, PM can be sufficiently oxidized at the protruding portion on the downstream side of the inner pipe, even if the amount of catalyst is less than the protruding portion on the upstream side of the inner pipe or no catalyst is provided. is there.
- FIG. 1 is a diagram showing a schematic configuration of an electrically heated catalyst according to Example 1.
- FIG. 3 is an enlarged view of a protruding portion of an inner tube of an electrically heated catalyst according to Example 1.
- FIG. 3 is a diagram showing a schematic configuration of an electrically heated catalyst according to Example 2.
- 6 is a diagram illustrating a schematic configuration of an electrically heated catalyst according to a modification of Example 2.
- FIG. 1 and 2 are diagrams showing a schematic configuration of an electrically heated catalyst (EHC) according to the present embodiment.
- FIG. 1 is a cross-sectional view of the EHC cut along its central axis.
- FIG. 2 is an enlarged view of a protruding portion that protrudes into the exhaust gas from the end face of the catalyst carrier in the inner pipe described later.
- the EHC 1 according to the present embodiment is provided in an exhaust pipe of an internal combustion engine mounted on a vehicle.
- the internal combustion engine may be a diesel engine or a gasoline engine.
- the EHC 1 according to the present embodiment can also be used in a vehicle that employs a hybrid system including an electric motor.
- the EHC 1 includes a catalyst carrier 3, a case 4, a mat 5, an inner tube 6, and an electrode 7.
- the catalyst carrier 3 is formed in a columnar shape, and is installed so that its central axis is coaxial with the central axis A of the exhaust pipe 2.
- An exhaust purification catalyst 13 is supported on the catalyst carrier 3. Examples of the exhaust purification catalyst 13 include an oxidation catalyst, a NOx storage reduction catalyst, a selective reduction NOx catalyst, and a three-way catalyst.
- the catalyst carrier 3 is formed of a material that generates electric resistance when heated.
- An example of the material of the catalyst carrier 3 is SiC.
- the catalyst carrier 3 has a plurality of passages extending in the direction in which the exhaust flows (that is, in the direction of the central axis A) and having a cross section perpendicular to the direction in which the exhaust flows in a honeycomb shape. Exhaust gas flows through this passage.
- the cross-sectional shape of the catalyst carrier 3 in the direction orthogonal to the central axis A may be an ellipse or the like.
- the central axis A is a central axis common to the exhaust pipe 2, the catalyst carrier 3, the inner pipe 6, and the case 4.
- the catalyst carrier 3 is accommodated in the case 4.
- An electrode chamber 9 is formed in the case 4. The details of the electrode chamber 9 will be described later.
- a pair of electrodes 7 are connected to the catalyst carrier 3 from the left and right directions through the electrode chamber 9. Electricity is supplied to the electrode 7 from a battery (not shown). When electricity is supplied to the electrode 7, the catalyst carrier 3 is energized. When the catalyst carrier 3 generates heat by energization, the exhaust purification catalyst 13 carried on the catalyst carrier 3 is heated, and its activation is promoted.
- Case 4 is made of metal.
- a stainless steel material can be exemplified.
- the case 4 includes an accommodating portion 4a including a curved surface parallel to the central axis A, and a tapered portion 4b that connects the accommodating portion 4a and the exhaust pipe 2 on the upstream side and the downstream side of the accommodating portion 4a. 4c.
- the passage cross-sectional area of the accommodating portion 4a is larger than the passage cross-sectional area of the exhaust pipe 2, and the catalyst carrier 3, the mat 5, and the inner pipe 6 are accommodated therein.
- the tapered portions 4b and 4c have a tapered shape in which the passage cross-sectional area decreases as the distance from the accommodating portion 4a increases.
- a mat 5 is sandwiched between the inner wall surface of the accommodating portion 4 a of the case 4 and the outer peripheral surface of the catalyst carrier 3. That is, the catalyst carrier 3 is supported by the mat 5 in the case 4.
- An inner tube 6 is sandwiched between the mats 5.
- the inner tube 6 is a tubular member centered on the central axis A.
- the mat 5 is divided into the case 4 side and the catalyst carrier 3 side by the inner tube 6 by sandwiching the inner tube 6.
- the mat 5 is made of an electrical insulating material. Examples of the material for forming the mat 5 include ceramic fibers mainly composed of alumina.
- the mat 5 is wound around the outer peripheral surface of the catalyst carrier 3 and the outer peripheral surface of the inner tube 6.
- the mat 5 is divided into an upstream portion 5a and a downstream portion 5b, and a space is formed between the upstream portion 5a and the downstream portion 5b. Since the mat 5 is sandwiched between the catalyst carrier 3 and the case 4, electricity is suppressed from flowing to the case 4 when the catalyst carrier 3 is energized.
- the inner tube 6 is made of stainless steel. Further, as shown in FIG. 2, an electrical insulating layer 61 is formed on the entire surface of the inner tube 6. Examples of a material for forming the electrical insulating layer 61 include ceramic or glass.
- the main body of the inner tube 6 may be formed of an electrical insulating material such as alumina.
- the inner tube 6 is longer than the mat 5 in the direction of the central axis A. Therefore, the upstream and downstream ends of the inner tube 6 protrude from the upstream and downstream end surfaces of the mat 5.
- the portions 6a and 6b protruding from the end face of the mat 5 in the inner pipe 6 into the exhaust are referred to as “projections”.
- An electrode chamber 9 is formed by a space in the case 4 between the upstream portion 5 a and the downstream portion 5 b of the mat 5. That is, in this embodiment, the electrode chamber 9 is formed over the entire outer peripheral surface of the catalyst carrier 3 between the upstream portion 5a and the downstream portion 5b of the mat 5.
- a space serving as an electrode chamber may be formed by forming a through hole only in a portion through which the electrode 7 of the mat 5 passes.
- An electrode support member 8 that supports the electrode 7 is provided in the through hole 4d opened in the case 4.
- the electrode support member 8 is made of an electrical insulating material, and is provided between the case 4 and the electrode 7 without a gap.
- the protrusions 6 a and 6 b of the inner pipe 6 are covered with an oxidation catalyst 10.
- the oxidation catalyst 10 further covers the electric insulating layer 61 that covers the surface of the inner tube 6. Further, the oxidation catalyst 10 does not cover the entire surface of the projecting portions 6 a and 6 b of the inner tube 6. That is, the outer peripheral surfaces of the projecting portions 6 a and 6 b of the inner tube 6 are covered with the oxidation catalyst 10 except for a predetermined range in contact with the end surface of the mat 5.
- the catalyst carrier 3 corresponds to the heating element according to the present invention.
- the heating element according to the present invention is not limited to the carrier supporting the catalyst.
- the heating element may be a structure installed on the upstream side of the catalyst.
- the case 4 corresponds to the case according to the present invention
- the mat 5 corresponds to the insulating support member according to the present invention
- the inner tube 6 corresponds to the inner tube according to the present invention.
- the oxidation catalyst 10 corresponds to a catalyst having an oxidation function according to the present invention.
- the catalyst having an oxidation function according to the present invention is not limited to an oxidation catalyst.
- the inner tube 6 whose entire surface is covered with the electrical insulating layer 61 is sandwiched between the mats 5.
- the protrusions 6 a and 6 b of the inner pipe 6 can suppress the condensed water from reaching the catalyst carrier along the end surface of the mat 5. Therefore, a short circuit between the catalyst carrier 3 and the case 4 due to condensed water at the end face of the mat 5 can also be suppressed.
- the inner pipe 6 does not necessarily protrude from both the upstream side and the downstream side of the mat 5.
- the oxidation catalyst 10 is provided on the surfaces of the protruding portions 6a and 6b of the inner tube 6.
- the oxidation catalyst 10 promotes the oxidation of PM adhering to the protrusions 6a and 6b. Thereby, it is possible to suppress a short circuit between the catalyst carrier 3 and the case 4 due to PM.
- the portion covered with the oxidation catalyst 10 becomes porous. Therefore, the condensed water tends to stay in the portion. Therefore, if the entire protrusions 6a and 6b of the inner pipe 6 are covered with the oxidation catalyst 10, the catalyst carrier 3 and the case 4 are easily short-circuited by the accumulated condensed water.
- the outer peripheral surfaces of the protruding portions 6 a and 6 b of the inner tube 6 are covered with the oxidation catalyst 10 except for a predetermined range in contact with the end surface of the mat 5. That is, the oxidation catalyst 10 is not provided in a predetermined range in contact with the end surface of the mat 5 on the outer peripheral surfaces of the protruding portions 6a and 6b of the inner tube 6. In the predetermined range, the electrical insulating layer 61 is exposed to the exhaust gas. The electrical insulating layer 61 has a water repellent effect. Therefore, the condensed water hardly stays in the predetermined range.
- the outside of the inner pipe 6 has a smaller exhaust flow rate than the inside. Therefore, PM hardly deposits on the outer peripheral surfaces of the protruding portions 6a and 6b of the inner tube 6 as compared with the inner peripheral surfaces of the protruding portions 6a and 6b. Further, in the projecting portions 6 a and 6 b of the inner pipe 6, PM is less likely to deposit in a portion near the end surface of the mat 5 than in a portion away from the end surface of the mat 5. Therefore, in the protrusions 6a and 6b of the inner tube 6, PM is most difficult to deposit in a portion near the end surface of the mat 5 on the outer peripheral surface. That is, PM does not easily accumulate within the predetermined range in the protrusions 6a and 6b of the inner pipe 6 even if the oxidation catalyst 10 is not provided.
- FIG. 3 is a diagram showing a schematic configuration of an electrically heated catalyst (EHC) according to the present embodiment.
- FIG. 3 is a cross-sectional view of the EHC cut along its central axis.
- the upstream and downstream ends of the inner pipe 6 protrude from the upstream and downstream end surfaces of the mat 5.
- the protruding portion 6 a on the upstream side of the inner tube 6 is covered with the oxidation catalyst 10, and the oxidizing catalyst 10 is not provided on the protruding portion 6 b on the downstream side of the inner tube 6.
- the configuration other than this point is the same as the configuration of the EHC according to the first embodiment. Therefore, also in the present embodiment, as in the first embodiment, the outer peripheral surface of the upstream protruding portion 6a of the inner pipe 6 is covered with the oxidation catalyst 10 except for a predetermined range in contact with the end surface of the mat 5. Yes.
- the exhaust gas passing through the EHC 1 is heated by heat generated by a chemical reaction in the exhaust purification catalyst 13 supported on the catalyst carrier 3.
- the temperature of the exhaust gas flowing out from the EHC 1 becomes higher than the temperature of the exhaust gas flowing into the EHC 1. Therefore, the temperature of the protruding portion 6 b on the downstream side of the inner tube 6 is higher than the temperature of the protruding portion 6 a on the upstream side of the inner tube 6. Even when the operating state of the internal combustion engine is reduced and the fuel cut control is executed, the temperature of the exhaust gas flowing into the EHC 1 is lowered. The temperature of the protruding portion 6b is unlikely to decrease.
- the protruding portion 6b on the downstream side of the inner tube 6 has a smaller amount of PM deposition and facilitates the oxidation of PM than the protruding portion 6a on the upstream side of the inner tube 6. Therefore, PM can be sufficiently oxidized in the protruding portion 6b on the downstream side of the inner pipe 6 without providing the oxidation catalyst 10. That is, it is possible to prevent PM from being deposited as the catalyst carrier 3 and the case 4 are short-circuited.
- the amount of the oxidation catalyst 10 that covers the protruding portion 6b on the downstream side of the inner pipe 6 does not necessarily have to be zero, and the oxidation catalyst 10 that covers the protruding portion 6a on the upstream side of the inner pipe 6 is not necessarily used. It may be less than the amount. Even in this case, the amount of the oxidation catalyst 10 used can be suppressed.
- PM is less likely to adhere to the outer peripheral surface of the protruding portion 6a on the upstream side of the inner tube 6 than the inner peripheral surface of the protruding portion 6a. If PM accumulation on the outer peripheral surface of the protrusion 6a can be suppressed, a short circuit due to PM between the catalyst carrier 3 and the case 4 on the upstream side of the EHC 1 can be suppressed.
- the oxidation catalyst 10 may not be provided on the inner peripheral surface of the protruding portion 6a on the upstream side of the inner pipe 6. According to such a configuration, the use of the oxidation catalyst 10 can be suppressed as much as possible.
- Electric heating catalyst (EHC) 3 Electric heating catalyst 4 .
- Catalyst carrier 4 Case 5 .
- Mat 6 Inner tube 6a, 6b .
- Projection 7 Electrode 10 .
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Abstract
Description
通電により発熱し、発熱することで触媒を加熱する発熱体と、
前記発熱体を収容するケースと、
前記発熱体と前記ケースとの間に設けられ、前記発熱体を支持すると共に電気を絶縁する絶縁支持部材と、
前記発熱体とケースとの間に位置するように前記絶縁支持部材に挟み込まれた管状の部材であって、その端部が前記絶縁支持部材の端面から排気中に突出しており、且つ、表面全体に電気絶縁層が形成されているか或いは電気絶縁材によって形成された内管と、
前記内管における前記絶縁支持部材の端面から排気中に突出している突出部の少なくとも外周面を、前記絶縁支持部材の端面と接する所定の範囲を除いて覆う酸化機能を有する触媒と、
を備える。
[EHCの概略構成]
図1及び2は、本実施例に係る電気加熱式触媒(EHC)の概略構成を示す図である。図1は、EHCをその中心軸に沿って切断した断面図である。図2は、後述する内管における触媒担体の端面から排気中に突出した突出部の拡大図である。
排気管2内又はEHC1のケース4内においては、内燃機関の冷間始動時等に、排気中の水分が凝縮することで、凝縮水が発生する。排気管2内又はケース4内で発生した凝縮水がケース4の内壁面を伝って流れマット5まで到達すると、該凝縮水がマット5内に浸入(浸潤)する場合がある。また、マット5内に水蒸気の状態で浸入した水分が該マット5内で凝縮する場合もある。
[EHCの概略構成]
図3は、本実施例に係る電気加熱式触媒(EHC)の概略構成を示す図である。図3は、EHCをその中心軸に沿って切断した断面図である。本実施例に係るEHC1においても、内管6の上流側及び下流側の端部は、マット5の上流側及び下流側の端面から突出している。そして、本実施例では、内管6の上流側の突出部6aのみが酸化触媒10によって覆われており、内管6の下流側の突出部6bには酸化触媒10が設けられていない。この点以外の構成は、実施例1に係るEHCの構成と同様である。従って、本実施例においても、実施例1と同様、内管6の上流側の突出部6aにおける外周面は、マット5の端面と接する所定の範囲を除いた部分が酸化触媒10によって覆われている。
EHC1における触媒担体3に流入した排気中のPMは、該触媒担体3にトラップされる。そのため、EHC1から流出する排気中のPM量は、EHC1に流入する排気中のPM量に比べて少ない。従って、内管6の下流側の突出部6bに付着するPM量は、内管6の上流側の突出部6aに付着するPM量よりも少ない。
尚、本実施例においては、内管6の下流側の突出部6bを覆う酸化触媒10の量を、必ずしも零としなくてもよく、内管6の上流側の突出部6aを覆う酸化触媒10の量よりも少なくしてもよい。この場合でも、酸化触媒10の使用量を抑制することができる。
3・・・触媒担体
4・・・ケース
5・・・マット
6・・・内管
6a,6b・・突出部
7・・・電極
10・・酸化触媒
Claims (3)
- 通電により発熱し、発熱することで触媒を加熱する発熱体と、
前記発熱体を収容するケースと、
前記発熱体と前記ケースとの間に設けられ、前記発熱体を支持すると共に電気を絶縁する絶縁支持部材と、
前記発熱体とケースとの間に位置するように前記絶縁支持部材に挟み込まれた管状の部材であって、その端部が前記絶縁支持部材の端面から排気中に突出しており、且つ、表面全体に電気絶縁層が形成されているか或いは電気絶縁材によって形成された内管と、
前記内管における前記絶縁支持部材の端面から排気中に突出している突出部の少なくとも外周面を、前記絶縁支持部材の端面と接する所定の範囲を除いて覆う酸化機能を有する触媒と、
を備える電気加熱式触媒。 - 前記内管が、前記絶縁支持部材の上流側及び下流側の両方の端面から排気中に突出しており、
該内管の下流側の突出部を覆う前記触媒の量が、該内管の上流側の突出部を覆う前記触媒の量に比べて少ない請求項1に記載の電気加熱式触媒。 - 前記内管の上流側の突出部のみが前記触媒によって覆われている請求項2に記載の電気加熱式触媒。
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JP2011554006A JP5354032B2 (ja) | 2011-03-09 | 2011-03-09 | 電気加熱式触媒 |
PCT/JP2011/055542 WO2012120669A1 (ja) | 2011-03-09 | 2011-03-09 | 電気加熱式触媒 |
EP11797293.5A EP2684596B1 (en) | 2011-03-09 | 2011-03-09 | Electrically heated catalyst |
US13/381,771 US8763379B2 (en) | 2011-03-09 | 2011-03-09 | Electrically heated catalyst |
CN201180002568.1A CN103442788B (zh) | 2011-03-09 | 2011-03-09 | 电加热催化剂 |
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CN112684832B (zh) * | 2019-10-17 | 2022-01-28 | 中国石油化工股份有限公司 | 克服碳化硅环状载体温度反应滞后的方法及设备 |
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JP3181219B2 (ja) * | 1996-02-06 | 2001-07-03 | トヨタ自動車株式会社 | 電気加熱式触媒装置 |
CN1680689A (zh) * | 2004-04-08 | 2005-10-12 | 中国环境科学研究院 | 用于内燃机排气净化装置的电加热器 |
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- 2011-03-09 JP JP2011554006A patent/JP5354032B2/ja not_active Expired - Fee Related
- 2011-03-09 CN CN201180002568.1A patent/CN103442788B/zh not_active Expired - Fee Related
- 2011-03-09 US US13/381,771 patent/US8763379B2/en not_active Expired - Fee Related
- 2011-03-09 WO PCT/JP2011/055542 patent/WO2012120669A1/ja active Application Filing
- 2011-03-09 EP EP11797293.5A patent/EP2684596B1/en not_active Not-in-force
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JPH0655080A (ja) * | 1992-05-20 | 1994-03-01 | W R Grace & Co | 触媒的変換装置用コア要素 |
JPH08193513A (ja) * | 1995-01-13 | 1996-07-30 | Calsonic Corp | 電気加熱触媒コンバータおよびその制御方法 |
JPH08266909A (ja) * | 1995-03-29 | 1996-10-15 | Showa Aircraft Ind Co Ltd | 電気加熱式触媒装置用メタル担体およびその製造方法 |
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JPWO2012120669A1 (ja) | 2014-07-07 |
CN103442788B (zh) | 2015-08-19 |
US20140033688A1 (en) | 2014-02-06 |
EP2684596B1 (en) | 2017-08-23 |
CN103442788A (zh) | 2013-12-11 |
US8763379B2 (en) | 2014-07-01 |
EP2684596A1 (en) | 2014-01-15 |
EP2684596A4 (en) | 2014-10-08 |
JP5354032B2 (ja) | 2013-11-27 |
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