JP7331553B2 - Electric heating catalyst device - Google Patents
Electric heating catalyst device Download PDFInfo
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- JP7331553B2 JP7331553B2 JP2019153667A JP2019153667A JP7331553B2 JP 7331553 B2 JP7331553 B2 JP 7331553B2 JP 2019153667 A JP2019153667 A JP 2019153667A JP 2019153667 A JP2019153667 A JP 2019153667A JP 7331553 B2 JP7331553 B2 JP 7331553B2
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- 239000003054 catalyst Substances 0.000 title claims description 28
- 238000005485 electric heating Methods 0.000 title description 2
- 229910052751 metal Inorganic materials 0.000 claims description 135
- 239000002184 metal Substances 0.000 claims description 135
- 230000002093 peripheral effect Effects 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 230000008646 thermal stress Effects 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 229910001120 nichrome Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 238000007751 thermal spraying Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910002543 FeCrAlY Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
Classifications
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Landscapes
- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
本発明は、電気加熱式触媒装置に関するものである。 The present invention relates to an electrically heated catalyst device.
内燃機関の排気通路などに配設される触媒装置について、触媒を担持した担体に通電して加熱をすることにより触媒の活性化を高める電気加熱式触媒装置が知られている。
例えば、特許文献1に記載の電気加熱式触媒装置は、触媒が担持された円柱状の担体と、担体の軸方向に延伸して同担体の外周面に設けられる表面電極と、表面電極の表面上に軸方向に並んで配設される複数の金属電極と、金属電極の一部を表面電極に固定する固定層とを有している。そして、表面電極の表面には、複数の金属電極が配設された配設部位と、複数の金属電極が配設されていない非配設部位とが軸方向に並んで設けられている。
2. Description of the Related Art Electrically heated catalyst devices are known that are installed in an exhaust passage of an internal combustion engine and the like, in which a carrier carrying a catalyst is energized and heated to increase the activation of the catalyst.
For example, the electrically heated catalyst device described in Patent Document 1 includes a cylindrical carrier on which a catalyst is supported, a surface electrode extending in the axial direction of the carrier and provided on the outer peripheral surface of the carrier, and a surface of the surface electrode. It has a plurality of metal electrodes arranged axially on the top and a fixing layer fixing a part of the metal electrodes to the surface electrode. On the surface of the surface electrode, an arrangement portion where a plurality of metal electrodes are arranged and a non-arrangement portion where a plurality of metal electrodes are not arranged are arranged side by side in the axial direction.
ところで、表面電極にあって複数の金属電極が配設されている配設部位にクラックが発生すると、以下のような不都合が生じるおそれがある。
すなわち、クラックが生じると、表面電極の配設部位には電気的な繋がりが弱い部位が生じることから、非配設部位における担体の電気抵抗は、そうした配設部位における担体の電気抵抗に比して相対的に小さくなる。そのため、上記配設部位に配設されている各金属電極のうちで担体の軸方向の末端に位置する各金属電極を端部金属電極とし、それら各端部金属電極の間に位置する金属電極を中間金属電極としたときに、担体の電気抵抗が小さい上記非配設部位と電気的に繋がっている端部金属電極には、配設部位の中間金属電極よりも多くの電流が流れるようになり、当該端部金属電極には電流が集中するようになる。このようにして端部金属電極に電流が集中すると、端部金属電極を固定している固定層にも多くの電流が流れるようになるため、当該固定層の発熱量が増加するおそれがある。
By the way, if a crack occurs in a portion of the surface electrode where a plurality of metal electrodes are arranged, the following problems may occur.
That is, when a crack occurs, a portion where the surface electrode is arranged has a weak electrical connection, so the electrical resistance of the carrier at the non-arranged portion is lower than the electric resistance of the carrier at such an arranged portion. relatively small. Therefore, among the metal electrodes arranged in the above-mentioned arrangement portions, the metal electrodes positioned at the ends in the axial direction of the carrier are defined as the end metal electrodes, and the metal electrodes positioned between the end metal electrodes. is the intermediate metal electrode, the end metal electrode electrically connected to the non-arranged portion where the electrical resistance of the carrier is small is made to flow more current than the intermediate metal electrode at the arranged portion. As a result, the current concentrates on the end metal electrode. When the current concentrates on the end metal electrode in this manner, a large amount of current also flows through the fixed layer fixing the end metal electrode, which may increase the amount of heat generated in the fixed layer.
上記課題を解決する電気加熱式触媒装置は、触媒が担持された円柱状の担体と、前記担体の軸方向に延伸して当該担体の外周面に設けられる表面電極と、前記表面電極の表面上に前記軸方向に並んで配設される複数の金属電極と、前記金属電極の一部を前記表面電極に固定する固定層とを有する。そして、前記表面電極の表面は、前記複数の金属電極が配設された配設部位と、前記複数の金属電極が配設されていない非配設部位とが前記軸方向に並んで設けられている。そして、前記配設部位に配設されている各金属電極のうちで前記担体の軸方向の末端に位置する各金属電極を端部金属電極とし、それら各端部金属電極の間に位置する金属電極を中間金属電極としたときに、前記端部金属電極を固定する前記固定層と前記表面電極との接触面積は、前記中間金属電極を固定する前記固定層と前記表面電極との接触面積よりも大きくされている。 An electrically heated catalyst device that solves the above problems comprises a columnar carrier on which a catalyst is supported, a surface electrode that extends in the axial direction of the carrier and is provided on the outer peripheral surface of the carrier, and on the surface of the surface electrode and a fixing layer for fixing a part of the metal electrodes to the surface electrode. On the surface of the surface electrode, an arrangement portion where the plurality of metal electrodes are arranged and a non-arrangement portion where the plurality of metal electrodes are not arranged are arranged side by side in the axial direction. there is Among the metal electrodes arranged in the arrangement portions, the metal electrodes positioned at the ends in the axial direction of the carrier are defined as end metal electrodes, and the metal electrodes positioned between the end metal electrodes are defined as end metal electrodes. When the electrode is an intermediate metal electrode, the contact area between the fixing layer for fixing the end metal electrode and the surface electrode is larger than the contact area between the fixing layer for fixing the intermediate metal electrode and the surface electrode. has also been made larger.
同構成によれば、上記の端部金属電極を固定する固定層と表面電極との接触面積は、上記の中間金属電極を固定する固定層と表面電極との接触面積よりも大きくなっている。従って、表面電極にクラックが生じることにより、端部金属電極を固定する固定層を流れる電流が多くなる場合でも、当該固定層と表面電極との接触面における電流密度についてはその増加が抑制されるため、当該固定層の発熱量の増加を抑えることができる。 According to this configuration, the contact area between the fixing layer for fixing the end metal electrode and the surface electrode is larger than the contact area between the fixing layer for fixing the intermediate metal electrode and the surface electrode. Therefore, even if a crack occurs in the surface electrode and the amount of current flowing through the fixed layer that fixes the end metal electrode increases, the increase in the current density at the contact surface between the fixed layer and the surface electrode is suppressed. Therefore, an increase in the amount of heat generated by the fixed layer can be suppressed.
以下、電気加熱式触媒装置を具体化した一実施形態について、図1~図6を参照して説明する。この電気加熱式触媒装置は、例えば自動車等の排気通路に設けられて、内燃機関から排出される排気を浄化する。 An embodiment embodying an electrically heated catalyst device will be described below with reference to FIGS. 1 to 6. FIG. This electrically heated catalyst device is provided, for example, in an exhaust passage of an automobile or the like, and purifies exhaust gas emitted from an internal combustion engine.
図1に示すように、電気加熱式触媒装置10は、円柱状の担体12を備えている。この担体12は、導電性を有する多孔質材料、例えばSiC(炭化ケイ素)などで形成されており、白金やパラジウム等の触媒が担持されている。排気は担体12の内部を当該担体12の軸方向(図1に示す矢印Z方向)に通過する。 As shown in FIG. 1, the electrically heated catalyst device 10 has a columnar carrier 12 . The carrier 12 is made of a conductive porous material such as SiC (silicon carbide), and supports a catalyst such as platinum or palladium. The exhaust gas passes through the inside of the carrier 12 in the axial direction of the carrier 12 (direction of arrow Z shown in FIG. 1).
図1や図2に示すように、担体12の外周面には、担体12の径方向に対向配置された一対の表面電極30が設けられている。
図1や図3に示すように、表面電極30は、矩形状の平面形状をなしており、担体12の軸方向に延設されている。表面電極30は、溶射によって担体12の表面に形成されるポーラス膜となっており、高温下での耐酸化性に優れた金属材料、例えばNiCr合金などで形成されている。
As shown in FIGS. 1 and 2 , a pair of surface electrodes 30 are provided on the outer peripheral surface of the carrier 12 so as to face each other in the radial direction of the carrier 12 .
As shown in FIGS. 1 and 3 , the surface electrode 30 has a rectangular planar shape and extends in the axial direction of the carrier 12 . The surface electrode 30 is a porous film formed on the surface of the carrier 12 by thermal spraying, and is made of a metal material having excellent oxidation resistance at high temperatures, such as a NiCr alloy.
各表面電極30の表面であって担体12の軸方向における一部の表面には、金属電極40が複数設けられている。表面電極30の表面には、複数の金属電極40が配設された配設部位30Aと、金属電極40が配設されていない非配設部位30Bとが担体12の軸方向に並んで設けている。 A plurality of metal electrodes 40 are provided on a part of the surface of each surface electrode 30 in the axial direction of the carrier 12 . On the surface of the surface electrode 30, an arrangement portion 30A in which a plurality of metal electrodes 40 are arranged and a non-arrangement portion 30B in which no metal electrode 40 is arranged are provided side by side in the axial direction of the carrier 12. there is
配設部位30Aは、表面電極30全体のうちで担体12の軸方向における略中央の部位に設けられている。非配設部位30Bは、表面電極30全体のうちで担体12の軸方向における両端の部位に設けられており、上記した配設部位30Aを両側から挟むように配置されている。 30 A of arrangement|positioning parts are provided in the substantially central part in the axial direction of the support|carrier 12 among the surface electrodes 30 whole. The non-arranged portions 30B are provided at both ends of the surface electrode 30 in the axial direction of the carrier 12, and are arranged so as to sandwich the above-described arranged portion 30A from both sides.
金属電極40は、担体12の周方向において表面電極30の形成領域全体に亘って延設されたリボン状の金属薄板であり、例えばFeCrAlY合金などの耐熱合金で形成されている。また、各金属電極40は、表面電極30の表面上において担体12の軸方向に略等間隔にて並んで配設されている。各金属電極40は、表面電極30の形成領域の片側から突出して延設されており、その突出した終端において一体化されている。図2に示すように、各表面電極30に設けられた金属電極40には電源300が接続される。 The metal electrode 40 is a ribbon-like thin metal plate extending in the circumferential direction of the carrier 12 over the entire region where the surface electrode 30 is formed, and is made of a heat-resistant alloy such as an FeCrAlY alloy. Also, the metal electrodes 40 are arranged on the surface of the surface electrode 30 at substantially equal intervals in the axial direction of the carrier 12 . Each metal electrode 40 protrudes and extends from one side of the forming area of the surface electrode 30, and is integrated at the protruding end. As shown in FIG. 2 , a power supply 300 is connected to the metal electrodes 40 provided on each surface electrode 30 .
図4に示すように、表面電極30の配設部位30Aに並設されている各金属電極40のうちで担体12の軸方向の末端に位置する各金属電極40を端部金属電極40Aとし、他の金属電極40、つまり各端部金属電極40Aの間に位置する金属電極40を中間金属電極40Bとしたときに、端部金属電極40Aの断面積は、中間金属電極40Bの断面積よりも大きくされている。より具体的には、端部金属電極40Aの線幅WAは、中間金属電極40Bの線幅WBはよりも長くなっている。なお、端部金属電極40Aの板厚を中間金属電極40Bの板厚よりも厚くすることにより、端部金属電極40Aの断面積を中間金属電極40Bの断面積よりも大きくしてもよい。 As shown in FIG. 4, among the metal electrodes 40 arranged side by side in the arrangement portion 30A of the surface electrode 30, each metal electrode 40 positioned at the end in the axial direction of the carrier 12 is defined as an end metal electrode 40A, When the other metal electrodes 40, that is, the metal electrodes 40 positioned between the end metal electrodes 40A are used as the intermediate metal electrodes 40B, the cross-sectional area of the end metal electrodes 40A is larger than that of the intermediate metal electrodes 40B. being enlarged. More specifically, the line width WA of the end metal electrode 40A is longer than the line width WB of the intermediate metal electrode 40B. The cross-sectional area of the end metal electrode 40A may be made larger than that of the intermediate metal electrode 40B by making the end metal electrode 40A thicker than the intermediate metal electrode 40B.
図5に示すように、金属電極40は、導電性を有する固定層50によって表面電極30に固定されている。固定層50は、溶射によって金属電極40及び表面電極30の表面に形成されるポーラス膜となっており、高温下での耐酸化性に優れた金属材料、例えばNiCr合金などで形成されている。 As shown in FIG. 5, the metal electrode 40 is fixed to the surface electrode 30 by a conductive fixing layer 50 . The fixed layer 50 is a porous film formed on the surfaces of the metal electrode 40 and the surface electrode 30 by thermal spraying, and is made of a metal material with excellent oxidation resistance at high temperatures, such as a NiCr alloy.
図1~図4に示すように、固定層50は、金属電極40及び表面電極30の表面上の複数箇所に点在して設けられており、金属電極40と表面電極30とを局所的に接合している。そして、端部金属電極40Aを固定する固定層50と表面電極30との接触面積は、中間金属電極40Bを固定する固定層50と表面電極30との接触面積よりも大きくなっている。一例として、本実施形態では、1つの端部金属電極40Aは担体12の周方向に間隔を空けて並んだ2つの固定層50で固定されており、1つの中間金属電極40Bは1つの固定層50で固定されている。また、隣り合う金属電極40では、固定層50が担体12の周方向にずらして配置されている。なお、端部金属電極40Aを固定する2つの固定層50と、中間金属電極40Bを固定する固定層50とは大きさがほぼ同じになっている。 As shown in FIGS. 1 to 4, the fixing layer 50 is provided scattered at a plurality of locations on the surface of the metal electrode 40 and the surface electrode 30, and the metal electrode 40 and the surface electrode 30 are locally fixed. are joined. The contact area between the fixing layer 50 fixing the end metal electrode 40A and the surface electrode 30 is larger than the contact area between the fixing layer 50 fixing the intermediate metal electrode 40B and the surface electrode 30 . As an example, in the present embodiment, one end metal electrode 40A is fixed by two fixed layers 50 spaced apart in the circumferential direction of the carrier 12, and one intermediate metal electrode 40B is fixed by one fixed layer. Fixed at 50. In addition, the fixed layers 50 of the metal electrodes 40 adjacent to each other are shifted in the circumferential direction of the carrier 12 . The two fixing layers 50 for fixing the end metal electrode 40A and the fixing layer 50 for fixing the intermediate metal electrode 40B have substantially the same size.
次に、本実施形態の電気加熱式触媒装置10の作用を説明する。
この電気加熱式触媒装置10では、電源300から金属電極40に電力が供給されると、金属電極40から表面電極30の配設部位30Aに電流が流れる。この配設部位30Aに流れた電流は、当該配設部位30Aに隣接する表面電極30の非配設部位30Bに流れることにより、表面電極30において担体12の軸方向に広がっていく。
Next, the operation of the electrically heated catalyst device 10 of this embodiment will be described.
In this electrically heated catalyst device 10 , when power is supplied from the power supply 300 to the metal electrode 40 , current flows from the metal electrode 40 to the arrangement portion 30A of the surface electrode 30 . The current flowing through this arrangement portion 30A spreads in the axial direction of the carrier 12 in the surface electrode 30 by flowing through the non-arrangement portion 30B of the surface electrode 30 adjacent to the arrangement portion 30A.
こうして表面電極30を流れる電流は、図2に示すように、対向する別の表面電極30に向かって担体12の内部を流れる。このようにして担体12の内部を電流が流れると、当該担体12は加熱されることにより、担体12に担持された触媒が活性化される。そして、この触媒の活性化により、担体12を通過する排気中の炭化水素、一酸化炭素、窒素酸化物等が浄化される。 The current flowing through the surface electrode 30 thus flows inside the carrier 12 toward another facing surface electrode 30, as shown in FIG. When the current flows through the inside of the carrier 12 in this way, the carrier 12 is heated and the catalyst supported on the carrier 12 is activated. Activation of this catalyst purifies hydrocarbons, carbon monoxide, nitrogen oxides, etc. in the exhaust gas passing through the carrier 12 .
ここで、図4に示すように、配設部位30Aにおいて隣り合う金属電極40の間の表面電極30には、金属電極40と表面電極30との熱膨張率の差による熱応力が生じやすい。そのため、配設部位30Aにおいて隣り合う金属電極40の間の表面電極30には、二点鎖線にて示すように熱応力によるクラックKが担体12の周方向に生じやすい。 Here, as shown in FIG. 4, thermal stress due to the difference in coefficient of thermal expansion between the metal electrodes 40 and the surface electrodes 30 is likely to occur in the surface electrodes 30 between the adjacent metal electrodes 40 in the arrangement portion 30A. Therefore, cracks K due to thermal stress are likely to occur in the circumferential direction of the carrier 12 in the surface electrodes 30 between the metal electrodes 40 adjacent to each other in the arrangement portion 30A, as indicated by the two-dot chain line.
図6に示すように、こうしたクラックKが生じると、表面電極30の配設部位30Aには、クラックKによって分断された部位であって中間金属電極40Bが固定されている分断部30Kが生じる。この分断部30Kは、表面電極30の配設部位30Aにおいて電気的な繋がりが弱い部位となっている。 As shown in FIG. 6, when such a crack K occurs, a split portion 30K, which is a portion split by the crack K and to which the intermediate metal electrode 40B is fixed, is created in the arrangement portion 30A of the surface electrode 30. As shown in FIG. This dividing portion 30K is a portion where the electrical connection is weak in the arrangement portion 30A of the surface electrode 30. As shown in FIG.
こうした分断部30Kについて担体12の軸方向における長さは、端部金属電極40Aと電気的に繋がっている表面電極30の非配設部位30Bの同長さと比較して短いことから、各分断部30Kと担体12との接触面積は、表面電極30の非配設部位30Bと担体12との接触面積よりも小さくなっている。 Since the length in the axial direction of the carrier 12 for such a divided portion 30K is shorter than the same length of the non-arranged portion 30B of the surface electrode 30 electrically connected to the end metal electrode 40A, each divided portion The contact area between 30K and carrier 12 is smaller than the contact area between non-arranged portion 30B of surface electrode 30 and carrier 12 .
そのため、担体12の直径方向に配置されているもう一方の表面電極30に向かって分断部30Kから流れる電流経路CAにおける担体12の電気抵抗は、担体12の直径方向に配置されているもう一方の表面電極30に向かって非配設部位30Bから流れる電流経路CBにおける担体12の電気抵抗よりも大きくなる。 Therefore, the electrical resistance of the carrier 12 in the current path CA flowing from the dividing portion 30K toward the other surface electrode 30 arranged in the diametrical direction of the carrier 12 is It is greater than the electrical resistance of the carrier 12 in the current path CB flowing from the non-arranged portion 30B toward the surface electrode 30 .
従って、電流経路CBを流れる電流、つまり端部金属電極40A及び端部金属電極40Aを固定する固定層50及び非配設部位30Bを介して担体12を流れる電流は、電流経路CAを流れる電流、つまり中間金属電極40B及び中間金属電極40Bを固定する固定層50及び配設部位30Aの分断部30Kを介して担体12を流れる電流よりも多くなる。 Therefore, the current flowing through the current path CB, that is, the current flowing through the carrier 12 via the end metal electrode 40A, the fixed layer 50 fixing the end metal electrode 40A, and the non-arranged portion 30B is the current flowing through the current path CA, That is, it is larger than the current flowing through the carrier 12 via the intermediate metal electrode 40B, the fixing layer 50 fixing the intermediate metal electrode 40B, and the dividing portion 30K of the arrangement portion 30A.
このようにして電流経路CBを流れる電流が多くなるにもかかわらず、仮に端部金属電極40Aを固定する固定層50と中間金属電極40Bを固定する固定層50の数が同じになっていると、端部金属電極40Aを固定する固定層50の発熱量が増加するようになる。こうして端部金属電極40Aを固定する固定層50の発熱量が増加すると、当該固定層50の熱応力が増加して同固定層50に亀裂が入ったり、溶断したりするおそれがある。 Even though the current flowing through the current path CB increases in this way, if the number of fixing layers 50 fixing the end metal electrode 40A and the number of fixing layers 50 fixing the intermediate metal electrode 40B are the same, , the calorific value of the fixing layer 50 fixing the end metal electrode 40A increases. When the amount of heat generated by the fixing layer 50 fixing the end metal electrode 40A increases in this way, the thermal stress of the fixing layer 50 increases, and the fixing layer 50 may crack or melt.
また、このようにして電流経路CBを流れる電流が多くなるにもかかわらず、仮に端部金属電極40Aの断面積と中間金属電極40Bの断面積とが同じになっていると、端部金属電極40Aの発熱量が増加するようになる。 In spite of the fact that the current flowing through the current path CB increases in this way, if the cross-sectional area of the end metal electrode 40A and the cross-sectional area of the intermediate metal electrode 40B are the same, the end metal electrode The amount of heat generated at 40A will increase.
この点、本実施形態では上述したように、1つの中間金属電極40Bを1つの固定層50で固定しているが、端部金属電極40Aについては2つの固定層50で固定しており、端部金属電極40Aを固定する固定層50と表面電極30との接触面積は、中間金属電極40Bを固定する固定層50と表面電極30との接触面積よりも大きくなっている。従って、表面電極30に上記クラックKが生じることにより、端部金属電極40Aを固定する固定層50を流れる電流が多くなる場合でも、当該固定層50と表面電極30との接触面における電流密度(単位面積に垂直な方向に単位時間に流れる電流値)についてはその増加が抑制されるため、当該固定層50の発熱量増加を抑えることができる。 In this regard, in this embodiment, as described above, one intermediate metal electrode 40B is fixed with one fixing layer 50, but the end metal electrode 40A is fixed with two fixing layers 50, and the end metal electrode 40A is fixed with two fixing layers 50. The contact area between the surface electrode 30 and the fixed layer 50 for fixing the intermediate metal electrode 40A is larger than the contact area between the fixed layer 50 for fixing the intermediate metal electrode 40B and the surface electrode 30 . Therefore, even if the current flowing through the fixing layer 50 fixing the end metal electrode 40A increases due to the crack K occurring in the surface electrode 30, the current density ( The current value flowing per unit time in the direction perpendicular to the unit area) is suppressed from increasing, so an increase in the amount of heat generated by the fixed layer 50 can be suppressed.
また、端部金属電極40Aの断面積についても、中間金属電極40Bの断面積よりも大きくしている。従って、表面電極30に上記クラックKが生じることにより、端部金属電極40Aを流れる電流が多くなる場合でも、端部金属電極40Aにおける電流密度についてはその増加が抑制されるため、当該端部金属電極40Aの発熱量の増加も抑えることができる。 Also, the cross-sectional area of the end metal electrode 40A is made larger than the cross-sectional area of the intermediate metal electrode 40B. Therefore, even if the current flowing through the end metal electrode 40A increases due to the crack K occurring in the surface electrode 30, the increase in the current density in the end metal electrode 40A is suppressed. It is also possible to suppress an increase in the amount of heat generated by the electrode 40A.
なお、担体12の軸方向における表面電極30の長さが長いほど、一対の表面電極30間の電流経路における担体12の電気抵抗は小さくなるため、一対の表面電極30間を流れる電流は多くなる。つまり、担体12の軸方向における表面電極30の長さと、一対の表面電極30間を流れる電流の大きさとは比例する。 Note that the longer the length of the surface electrode 30 in the axial direction of the carrier 12, the smaller the electrical resistance of the carrier 12 in the current path between the pair of surface electrodes 30, so the current flowing between the pair of surface electrodes 30 increases. . That is, the length of the surface electrode 30 in the axial direction of the carrier 12 is proportional to the magnitude of the current flowing between the pair of surface electrodes 30 .
ここで、表面電極30の上記分断部30Kについて担体12の軸方向における長さは、担体12の軸方向における各金属電極40の配設ピッチに比例する。また、図3に示すように、担体12の軸方向における各金属電極40の配設ピッチは、担体12の軸方向における各固定層50の平均配設ピッチPとほぼ同じである。そこで、端部金属電極40Aを固定する固定層50と端部金属電極40Aに隣接して広がる非配設部位30Bの軸方向Zにおける末端までの距離を距離Lとする。この場合において、平均配設ピッチPに対する距離Lの比RL(R=L/P)が大きいほど、クラックKが発生したときには、上記分断部30Kの軸方向Zの長さを基準としたときの上記非配設部位30Bの軸方向Zの長さは長くなるため、図6に示した電流経路CAの電流に対する電流経路CBの電流増加量は多くなる。従って、そうした電流経路CBの電流増加による固定層50の発熱を好適に抑えるには、上記比RLが大きい電気加熱式触媒装置ほど、中間金属電極40Bを固定する固定層50と表面電極30との接触面積に対して、端部金属電極40Aを固定する固定層50と表面電極30との接触面積をより大きくすることが望ましい。例えば、1つの端部金属電極40Aを固定する固定層50の配設数をXとしたときに、次式(1)を満たすように配設数Xを設定してもよい。なお、下記の係数K1は、電気加熱式触媒装置の仕様に合わせて変更される適合値である。 Here, the length of the divided portion 30K of the surface electrode 30 in the axial direction of the carrier 12 is proportional to the arrangement pitch of the metal electrodes 40 in the axial direction of the carrier 12 . Further, as shown in FIG. 3 , the arrangement pitch of the metal electrodes 40 in the axial direction of the carrier 12 is substantially the same as the average arrangement pitch P of the fixed layers 50 in the axial direction of the carrier 12 . Therefore, let L be the distance between the fixed layer 50 for fixing the end metal electrode 40A and the end in the axial direction Z of the non-arrangement portion 30B that spreads adjacent to the end metal electrode 40A. In this case, the larger the ratio RL (R=L/P) of the distance L to the average arrangement pitch P, the greater the number of cracks K when the length of the dividing portion 30K in the axial direction Z is used as a reference. Since the length of the non-arrangement portion 30B in the axial direction Z is longer, the amount of increase in current in the current path CB with respect to the current in the current path CA shown in FIG. 6 is increased. Therefore, in order to suitably suppress the heat generation of the fixed layer 50 due to the current increase in the current path CB, the larger the ratio RL of the electrically heated catalyst device, the more the fixed layer 50 fixing the intermediate metal electrode 40B and the surface electrode 30 should be. It is desirable to increase the contact area between the fixing layer 50 fixing the end metal electrode 40A and the surface electrode 30 with respect to the contact area. For example, when X is the number of fixed layers 50 that fix one end metal electrode 40A, the number X may be set so as to satisfy the following equation (1). Note that the coefficient K1 below is a suitable value that is changed according to the specifications of the electrically heated catalyst device.
配設数X≧係数K1×比RL…(1)
同様に、そうした電流経路CBの電流増加による端部金属電極40Aの発熱を好適に抑えるには、上記比RLが大きい電気加熱式触媒装置ほど、中間金属電極40Bの断面積SBに対する端部金属電極40Aの断面積SAの比である断面積比RS(RS=SA/SB)をより大きくすることが望ましい。例えば、次式(2)を満たすように断面積比RSを設定してもよい。なお、下記の係数K2も、電気加熱式触媒装置の仕様に合わせて変更される適合値である。
Arrangement number X≧coefficient K1×ratio RL (1)
Similarly, in order to suitably suppress the heat generation of the end metal electrode 40A due to the current increase in the current path CB, the electrically heated catalyst device having the larger ratio RL should have the end metal electrode relative to the cross-sectional area SB of the intermediate metal electrode 40B. It is desirable to increase the cross-sectional area ratio RS (RS=SA/SB), which is the ratio of the cross-sectional areas SA of 40A. For example, the cross-sectional area ratio RS may be set so as to satisfy the following equation (2). Note that the coefficient K2 below is also a suitable value that is changed according to the specifications of the electrically heated catalyst device.
断面積比RS≧係数K×比RL…(2)
以上説明したように、本実施形態では以下の効果が得られる。
(1)端部金属電極40Aを固定する固定層50と表面電極30との接触面積は、中間金属電極40Bを固定する固定層50と表面電極30との接触面積よりも大きくなっている。従って、表面電極30の配設部位30AにクラックKが生じた場合でも、端部金属電極40Aを固定する固定層50の発熱量の増加を抑えることができる。そしてこれにより当該固定層50の信頼性などが向上するようになる。
Cross-sectional area ratio RS≧coefficient K×ratio RL (2)
As described above, the present embodiment provides the following effects.
(1) The contact area between the fixing layer 50 fixing the end metal electrode 40A and the surface electrode 30 is larger than the contact area between the fixing layer 50 fixing the intermediate metal electrode 40B and the surface electrode 30 . Therefore, even if a crack K occurs in the arrangement portion 30A of the surface electrode 30, it is possible to suppress an increase in the amount of heat generated by the fixing layer 50 that fixes the end metal electrode 40A. As a result, the reliability of the fixed layer 50 is improved.
(2)端部金属電極40Aの断面積は、中間金属電極40Bの断面積よりも大きくなっている。従って、表面電極30の配設部位30AにクラックKが生じた場合でも、端部金属電極40Aの発熱量増加を抑えることができる。 (2) The cross-sectional area of the end metal electrode 40A is larger than the cross-sectional area of the intermediate metal electrode 40B. Therefore, even if a crack K occurs in the arrangement portion 30A of the surface electrode 30, an increase in the amount of heat generated by the end metal electrode 40A can be suppressed.
なお、本実施形態は、以下のように変更して実施することができる。本実施形態及び以下の変更例は、技術的に矛盾しない範囲で互いに組み合わせて実施することができる。
・端部金属電極40Aの断面積と中間金属電極40Bの断面積とを同じにしてよい。この場合でも、上記(2)以外の効果を得ることができる。
In addition, this embodiment can be changed and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- The cross-sectional area of the end metal electrode 40A and the cross-sectional area of the intermediate metal electrode 40B may be the same. Even in this case, effects other than the above (2) can be obtained.
・端部金属電極40Aを固定する固定層50と表面電極30との接触面積を、中間金属電極40Bを固定する固定層50と表面電極30との接触面積よりも大きくするために、端部金属電極40Aを固定する固定層50の数を、中間金属電極40Bを固定する固定層50の数よりも多くしたが、他の態様で同接触面積を異ならせてもよい。例えば、端部金属電極40Aを固定する固定層50の形状を、中間金属電極40Bを固定する固定層50よりも大きい形状にしてもよい。 In order to make the contact area between the fixing layer 50 for fixing the end metal electrode 40A and the surface electrode 30 larger than the contact area between the fixing layer 50 for fixing the intermediate metal electrode 40B and the surface electrode 30, the end metal Although the number of fixing layers 50 for fixing the electrode 40A is greater than the number of fixing layers 50 for fixing the intermediate metal electrode 40B, the same contact area may be varied in another manner. For example, the fixing layer 50 for fixing the end metal electrode 40A may be shaped larger than the fixing layer 50 for fixing the intermediate metal electrode 40B.
10…電気加熱式触媒装置、12…担体、30…表面電極、30A…配設部位、30B…非配設部位、30K…分断部、40…金属電極、40A…端部金属電極、40B…中間金属電極、50…固定層、300…電源。 DESCRIPTION OF SYMBOLS 10...Electric heating type catalyst device 12...Carrier 30...Surface electrode 30A...Arrangement part 30B...Non-arrangement part 30K...Dividing part 40...Metal electrode 40A...End metal electrode 40B...Intermediate Metal electrode, 50... fixed layer, 300... power source.
Claims (1)
前記表面電極の表面は、前記複数の金属電極が配設された配設部位と、前記複数の金属電極が配設されていない非配設部位とが前記軸方向に並んで設けられており、
前記配設部位に配設されている各金属電極のうちで前記担体の軸方向の末端に位置する各金属電極を端部金属電極とし、それら各端部金属電極の間に位置する金属電極を中間金属電極としたときに、
全ての前記固定層の大きさは、同じになっており、
前記端部金属電極を固定する前記固定層の数が前記中間金属電極を固定する前記固定層の数よりも多いことで、前記端部金属電極を固定する前記固定層と前記表面電極との接触面積は、前記中間金属電極を固定する前記固定層と前記表面電極との接触面積よりも大きくされている
電気加熱式触媒装置。 A columnar carrier supporting a catalyst, a surface electrode extending in the axial direction of the carrier and provided on the outer peripheral surface of the carrier, and a plurality of electrodes arranged side by side in the axial direction on the surface of the surface electrode. and a fixed layer fixing a part of the metal electrode to the surface electrode,
On the surface of the surface electrode, an arrangement portion where the plurality of metal electrodes are arranged and a non-arrangement portion where the plurality of metal electrodes are not arranged are arranged side by side in the axial direction,
Among the metal electrodes arranged in the arrangement portions, the metal electrodes positioned at the end in the axial direction of the carrier are defined as end metal electrodes, and the metal electrodes positioned between the end metal electrodes are defined as end metal electrodes. When used as an intermediate metal electrode,
All the fixing layers have the same size,
Since the number of the fixing layers for fixing the end metal electrodes is larger than the number of the fixing layers for fixing the intermediate metal electrodes, the fixing layers for fixing the end metal electrodes are in contact with the surface electrodes. The electrically heated catalyst device, wherein the area is larger than the contact area between the fixed layer for fixing the intermediate metal electrode and the surface electrode.
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JP2012106199A (en) | 2010-11-18 | 2012-06-07 | Toyota Motor Corp | Electric heating type catalyst |
JP2012106164A (en) | 2010-11-16 | 2012-06-07 | Toyota Motor Corp | Electrical heating type catalyst |
WO2013098889A1 (en) | 2011-12-27 | 2013-07-04 | トヨタ自動車株式会社 | Electrically heated catalytic converter and method for manufacturing same |
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JP2012106199A (en) | 2010-11-18 | 2012-06-07 | Toyota Motor Corp | Electric heating type catalyst |
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