JP2009082873A - Electrically heating type catalyst apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently exhibit exhaust gas treatment function even if a catalyst carrier having NTC characteristic is used. <P>SOLUTION: The electrically heating type catalyst apparatus is an electrically heating type catalyst apparatus for heating a catalyst for exhaust gas treatment by Joule heat. A positive electrode and a negative electrode are arranged in prescribed positions of this electrically heating type catalyst apparatus and a catalyst carrier electrically connects the positive electrode and negative electrode. The catalyst carrier has NTC characteristic that the resistance is continuously decreased when the temperature is increased. Partitioning means partitions the catalyst carrier with an insulating material and at least part of partitioned electric current paths are connected in series by a conductive material to make an electric current path for electric current flowing through the catalyst carrier long as compared with that in the case no partitioning by the insulating material is done. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an energization heating type catalytic device for purifying exhaust gas of an automobile, and, for example, NTC (Negative Temperature Coefficient: NTC) whose resistance value continuously decreases as the temperature rises, such as silicon carbide SiC. The present invention relates to a technique using a current path having characteristics.

  Generally, in order to fully exhibit the exhaust gas purification ability of the catalyst device, it is preferable to raise the temperature inside the catalyst device uniformly to the catalyst activation temperature. Therefore, for example, as shown in FIG. 1 of Patent Document 1, on the outer peripheral surface of the electrically heated honeycomb body constituting the catalyst device, opposing portions set at a desired peripheral length interval In addition, there has been proposed a technique that uses an electrode plate having a predetermined circumferential length arranged opposite to each other. According to this configuration, the resistance value per unit volume in the catalyst carrier in which current flows from one of the opposing electrode plates to the other becomes substantially the same, and the inside of the honeycomb body is heated uniformly by resistance (Patent Document 1). See paragraph 0014 of the description).

  However, in the above configuration, consideration is not sufficiently given to the case where the catalyst carrier of the catalyst device has NTC characteristics. Therefore, once the temperature distribution of the catalyst carrier of the catalyst device becomes non-uniform, this tendency may be promoted. Specifically, once the temperature of a part of the catalyst carrier rises as the supply current to the electrode plate increases, the resistance value of part of the catalyst carrier decreases due to the NTC characteristics, so that more current flows through that part. There is a risk of promoting a local temperature rise. As a result, the temperature distribution and activation state of the current path of the catalyst device also become non-uniform, and there is a possibility that the catalyst device cannot fully exhibit the exhaust gas purification function.

Japanese Patent Laid-Open No. 5-115579

  The present invention has been made in view of, for example, the above-described problems, and provides an electrically heated catalyst device that can sufficiently exhibit an exhaust gas purification function even when a catalyst carrier having NTC characteristics is used. Let it be an issue.

  In order to solve the above problems, an electrically heated catalyst device of the present invention is an electrically heated catalyst device that heats an exhaust gas purification catalyst by Joule heat, and is installed at a predetermined position of the electrically heated catalyst device. The positive electrode and the negative electrode are electrically connected to each other, and the catalyst carrier having an NTC characteristic in which the resistance value continuously decreases as the temperature rises, and the catalyst carrier by an insulating member A partition means for partitioning and connecting at least a part of the partitioned current paths in series with a conductive member to lengthen the current path of the current flowing through the catalyst carrier as compared with the case where the current is not partitioned by the insulating member With.

  According to the electrically heated catalyst device of the present invention, the exhaust gas purifying catalyst is heated by Joule heat. A positive electrode and a negative electrode are installed at predetermined positions of the energization heating type catalyst device. For example, a positive electrode is installed on the exhaust gas inlet side, and a negative electrode is installed on the outlet side. However, the positions of the positive electrode and the negative electrode may be reversed, or may be either one end. The positive electrode and the negative electrode are electrically connected by a catalyst carrier. This catalyst carrier is a semiconductor having an NTC characteristic in which the resistance value continuously decreases as the temperature rises, such as silicon carbide SiC. The catalyst carrier heats the supported catalyst by generating Joule heat when energized. In addition, the partition means partitions this catalyst carrier with an insulating member, and at least a part of the partitioned catalyst carrier is connected in series with a conductive member. As a result, the current path of the current flowing through the catalyst carrier becomes longer than when there is no insulating member.

  Here, if it is not partitioned by the insulating member, as pointed out as the above problem, when the temperature of a part of the catalyst carrier rises compared to the surroundings, the resistance value decreases compared to other parts due to the NTC characteristics. As a result, a larger amount of current flows, which may promote non-uniform temperature distribution. As a result, the exhaust gas purification function of the catalyst supported on the catalyst carrier may not be sufficiently exhibited.

  However, according to the configuration of the electrically heated catalyst device of the present invention, as described above, the current path in the catalyst carrier is made longer than in the case where there is no insulating member. Then, the current flows finely through the entire catalyst carrier, and the difference in the density distribution of the current flowing through the catalyst is further reduced. Even if the temperature of a part of the catalyst carrier rises compared to the other part, since the part and the other part are connected in series as a current path, the current density flowing through each is the same. Non-uniformity is not promoted. Rather, because of the NTC characteristics, some resistance values that increase in temperature are lower than those in other parts, so Joule heat generated in these parts is lower than in other parts. That is, according to this configuration, the temperature difference in the catalyst carrier is eliminated.

  As can be seen from the above, according to the current heating type catalyst device of the present invention, the non-uniform temperature distribution in the internal catalyst carrier can be eliminated even if the current path having the NTC characteristic is used. It is possible to sufficiently exhibit the exhaust gas purification function of the supported catalyst.

  In one aspect of the electrically heated catalyst device of the present invention, the catalyst carrier is also an exhaust gas passage in the electrically heated catalyst device, and the partition means includes a plurality of sections of the exhaust gas passage by the insulating member. The catalyst carrier is partitioned so that the insulating member extends along the passage of the exhaust gas.

  According to this aspect, the catalyst carrier is also an exhaust gas passage in the energization heating type catalyst device. For example, the catalyst carrier is formed in a honeycomb shape, and a space serving as an exhaust gas passage is provided so that the exhaust gas is in contact with the supported catalyst. The partition means partitions the catalyst carrier so that the cross section of the exhaust gas passage is partitioned into a plurality of portions by the insulating member, and the insulating member extends along the exhaust gas passage. Each section is at least partially connected in series by the conductive member. For example, the compartments connected in series are connected to the previous compartment at one end and to the rear compartment at the other end. Then, current flows sequentially through the respective sections while reciprocating along the exhaust gas passage from the positive electrode toward the negative electrode. Accordingly, the catalyst is similarly activated in any of the sections, so that the exhaust gas passing therethrough can be uniformly purified.

  In this aspect, the partition means may partition the catalyst carrier such that a cross-sectional area of a section located near the center in the cross section of the exhaust gas passage is larger than that near the outer periphery.

  According to this configuration, in the cross section of the exhaust gas passage (that is, the catalyst carrier), heat is more concentrated in the section closer to the center than in the vicinity of the outer periphery, but the sectional area of the section located near the center is larger than that near the outer periphery. Since the current density is increased, the current density is lower than that near the outer periphery, and heat generation can be suppressed. Note that the “section located near the center” does not necessarily need to be a section located at the center of the catalyst carrier, and may be a section located closer to the center than the section located at the outermost periphery.

  Alternatively, in this aspect, the partition means may partition the catalyst support such that at least two sections located near the center in the cross section of the exhaust gas passage are connected in parallel.

  According to this configuration, in the cross section of the exhaust gas passage (that is, the catalyst carrier), heat is more concentrated in the section closer to the center than in the outer periphery. By considering it as one section with an expanded cross-sectional area, heat generation near the center can be suppressed as in the above-described embodiment.

  Alternatively, in this aspect, the catalyst carrier may be configured such that the resistance value of the section located near the center in the cross section of the exhaust gas passage is smaller than that near the outer periphery.

  According to this configuration, in the cross section of the exhaust gas passage (that is, the catalyst carrier), heat is more concentrated in the section closer to the center than in the vicinity of the outer periphery. By reducing the resistance value compared with that near the outer periphery, the same current can be obtained. The Joule heat generated even when flowing through can be reduced, so that heat generation near the center can be suppressed.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings as the best mode for carrying out the invention.

(1) First Embodiment First, a detailed configuration of the internal combustion engine 40 will be described with reference to FIG. Here, FIG. 1 is a schematic cross-sectional view showing the internal combustion engine 40 according to the first embodiment.

  In FIG. 1, an intake pipe 206 communicates the cylinder 201 with the outside air, and is configured to be able to suck air into the cylinder 201 of the internal combustion engine 40. In the pipe of the intake pipe 206, a cleaner that purifies the intake air, an air flow meter that detects the mass flow rate of the intake air (that is, the intake air amount), an intake air temperature sensor that detects the temperature of the intake air, A throttle valve that adjusts the intake air amount, a throttle position sensor that detects the opening of the throttle valve, and a throttle valve motor that drives the throttle valve based on the amount of depression of the accelerator pedal by the driver are provided. Further downstream, a surge tank 2061 that stores intake air and distributes it to each of the plurality of cylinders, a pressure sensor 2062 that detects an intake pipe pressure in the surge tank 2061, and a fuel injection valve 207 are provided. The fuel injection valve 207 injects the fuel supplied from the fuel tank 223 into the intake pipe 206 according to the control of the control device 30. The injected fuel is mixed with the air sucked through the intake pipe 206 to form an air-fuel mixture, which is used for combustion in the cylinder 201.

  The fuel tank 223 stores fuel supplied from the fuel supply port 311. This fuel is used for combustion of the internal combustion engine 40. The fuel supplied here is, for example, gasoline, alcohol, or a mixed fuel thereof. The pump 225 appropriately sucks up this fuel and supplies it to the fuel injection valve 207. The fuel sensor 224 detects the amount of stored fuel and transmits it to the control device 30.

  The internal combustion engine 40 burns the air-fuel mixture in the cylinder 201 by ignition of the spark plug 202. The reciprocating motion of the piston according to the explosion force at this time is converted into the rotational motion of the crankshaft via the connection rod, and this rotational motion becomes the driving force. Various sensors such as a water temperature sensor that detects the temperature of the cooling water and a crank position sensor that can detect the rotation speed of the internal combustion engine 40 by periodically detecting the crank angle are disposed around the internal combustion engine 40. Yes. The output of each sensor is supplied to the control device 30 as a corresponding detection signal. The air-fuel mixture combusted inside the cylinder 201 becomes exhaust gas, passes through the exhaust valve 209 that opens and closes in conjunction with the opening and closing of the intake valve 208, and is exhausted through the exhaust pipe 210. These opening / closing timings are adjusted by, for example, a variable valve operating apparatus configured by a known variable valve timing-intelligent system (VVT-i).

  The control device 30 includes a central processing unit (CPU), a read only memory (ROM) that stores a control program, and an occasional write / read memory (RAM) that stores various data. It is configured as a central logic operation circuit. The control device 30 is connected via a bus to an input port that receives input signals from various sensors and an output port that sends control signals to various actuators such as the variable valve timing mechanism and the electrically heated catalyst device 50.

  An air-fuel ratio sensor 221 and an electrically heated catalyst device 50 are provided in the pipe line of the exhaust pipe 210.

  The air-fuel ratio sensor 221 is made of, for example, a zirconia solid electrolyte, and detects the air-fuel ratio (A / F) of the exhaust gas in the exhaust pipe 210 and supplies a detection signal to the control device 30. Based on this detection signal, air-fuel ratio feedback correction is performed.

  An electrically heated catalyst device (EHC) 50 is a three-way catalyst having a noble metal such as platinum or rhodium as an active component, for example, nitrogen oxide (NOx), carbon monoxide (CO) in exhaust gas. And has a function of removing hydrocarbons (HC) and the like. In addition, the energization heating type catalyst device 50 is controlled in the energized state under the control of the control device 30 and is heated during energization to raise its temperature to the lowest catalyst activation temperature (for example, about 350 ° C.).

  Here, the structure of the electrically heated catalyst device 50 according to the first embodiment will be described in detail with reference to FIGS. First, a comparative example will be described, and then the first embodiment will be described.

  The structure of the electrically heated catalyst device 50 according to the comparative example is shown in FIGS. Here, FIG. 2 is a schematic cross-sectional view when the electrically heated catalyst device 50 according to the comparative example is viewed from the side. FIG. 3 is a schematic cross-sectional view of the electrically heated catalyst device 50 according to the comparative example when viewed from the front side on the exhaust gas inlet side at the position L in FIG.

  As shown in FIG. 2, the electrically heated catalyst device 50 includes an outer shell 51 that forms the outer shape of the electrically heated catalyst device 50 and has an open connection port to the exhaust pipe 210, and is surrounded by the outer shell 51. The energized catalyst carrier 52, a power source 531 for energizing the energized catalyst carrier 52, a positive electrode 532, a negative electrode 533, and a switch 534 that switches an energized state under the control of the control device 30. Here, the energized catalyst carrier 52 is, for example, a carrier for supporting a powdery catalyst, and is configured to allow exhaust gas to pass through the inside thereof, for example, like a pellet or a honeycomb. In addition, as shown by the thick arrow in FIG. 2, exhaust gas flows from left to right. In addition, the current-carrying catalyst carrier 52 is a conductor or semiconductor having NTC characteristics, such as silicon carbide SiC, and has a characteristic that when its temperature is increased by Joule heat during energization, its own resistance value decreases accordingly.

  In the electrically heated catalyst device 50 according to the comparative example, as shown in FIG. 2, there is only one electrically conductive catalyst carrier 52, in other words, there is no insulator that partitions the electrically conductive catalyst carrier 52. Here, in order to heat the entire energized catalyst carrier 52 to the activation temperature, a positive electrode 532 is installed on the exhaust gas inlet side, and a negative electrode 533 is installed on the outlet side. Then, as indicated by a broken line arrow in FIG. 2, the current supplied from the power source 531 when energized flows from the inlet side to the outlet side of the exhaust gas (however, the direction of the current may be reversed). Absent).

  At this time, as shown in FIG. 3, since the outer peripheral portion of the energized catalyst carrier 52 is in contact with a member that does not generate heat, such as the outer shell 51, heat is dissipated. If it does so, the temperature of the center part of the electricity supply catalyst support | carrier 52 will become high compared with the temperature of an outer peripheral part. If it does so, the resistance value of the center part of the electricity supply catalyst support | carrier 52 which has an NTC characteristic will become low compared with the resistance value of an outer peripheral part. Then, the current passes through the central portion rather than the outer peripheral portion of the energized catalyst carrier 52. If it does so, the center part of the electricity supply catalyst support | carrier 52 will be heated further, and there exists a possibility that the nonuniformity of temperature distribution may be promoted. As a result, the outer peripheral portion of the energized catalyst carrier 52 is not activated, and the exhaust gas passing through the outer peripheral portion may not be sufficiently purified. In FIG. 3, the density of the current-carrying catalyst carrier 52 schematically indicates non-uniformity of the temperature distribution, and a symbol including an X in a circle indicates from the front to the back (that is, exhaust gas). It shows that a current flows from the gas inlet side to the outlet side. Incidentally, in FIG. 5 described later, a symbol including a dot in a circle indicates that a current flows from the back to the front (that is, from the exhaust gas outlet side to the inlet side).

  On the other hand, the electrically heated catalyst device 50 according to the first embodiment is configured as shown in FIG. Here, FIG. 4 is a schematic cross-sectional view of the electrically heated catalyst device 50 according to the first embodiment as viewed from the side.

  As shown in FIG. 4, unlike the comparative example, the electrically heated catalyst device 50 according to the first embodiment includes a plurality of electrically conductive catalyst carriers 52, an insulating material 54 partitioning them, and at least a part of them. And a conductive material 55 electrically connected in series. In order to heat the entire energized catalyst carrier 52 to the activation temperature, a positive electrode 532 is installed at the upper end of the exhaust gas outlet, and a negative electrode 533 is installed at the lower end of the outlet. Then, as indicated by broken line arrows in FIG. 4, the current supplied from the power source 531 during energization from the top while reciprocating along the direction in which the exhaust gas flows through the plurality of energized catalyst carriers 52 connected in series. Flows downward (however, the current direction may be reversed).

  A modification in which this configuration is viewed from another viewpoint will be described with reference to FIG. Here, FIG. 5 is a schematic cross-sectional view of the electrically heated catalyst device 50 according to the first embodiment as viewed from the front side on the exhaust gas inlet side at the position L in FIG.

  In FIG. 5, the energization heating type catalyst device 50 is composed of 16 energization catalyst carriers 52, which are partitioned by an insulating material 54. At least two of the sixteen energized catalyst carriers 52 are electrically connected in series. In FIG. 5, all 16 energized catalyst carriers 52 are No. 01 to No. They are connected in series in the order of 16. Specifically, no. A positive electrode 532 is connected to one end of the energized catalyst carrier 52 of No. 01 (for example, the exhaust gas inlet side). A negative electrode 533 is installed at one end of each of the sixteen energized catalyst carriers 52. And No. The other end of the energized catalyst carrier 52 of No. 01 (for example, the exhaust gas outlet side) is No. 02 is electrically connected to the other end of the energized catalyst carrier 52 by a conductive material 55. No. One end of the current-carrying catalyst carrier 52 of No. 02 is 03 is electrically connected to one end of a current-carrying catalyst carrier 52 by a conductive material 55. A similar configuration is shown in Continue up to 16 energized catalyst carriers 52. Therefore, the current supplied from the power source 531 during energization flows from the positive electrode 532 and each energized catalyst carrier 52 is set to No. 01 to No. In order of 16, the gas flows while reciprocating along the direction in which the exhaust gas flows, and finally reaches the negative electrode 533. At this time, since a plurality of current-carrying catalyst carriers 52 are connected in series, the current-carrying catalyst carriers 52 (for example, each of the current-carrying catalyst carriers 52 of Nos. 06, 07, 10, and 11) located in the center part, Passing through the current-carrying catalyst carrier 52 (for example, each of the current-carrying catalyst carriers 52 of Nos. 01, 02, 03, 04, 05, 08, 09, 12, 13, 14, 15, and 16) located on the outer periphery. Is equal to the current to be generated.

  4 and FIG. 5, as will be described in detail below, even if the temperature of the energized catalyst carrier 52 located in the central portion is higher than that in the outer peripheral portion, the temperature distribution is not improved. The uniformity is relaxed, and thus the energized catalyst carrier 52 can be activated uniformly.

  First, in achieving the above-mentioned object, it is important to minimize the temperature difference between the plurality of divided energized catalyst carriers 52. In the energization heating type catalyst device 50, the major factor that determines the temperature of the energization catalyst carrier 52 is Joule heat. Joule heat (that is, consumed electric energy) generated in the energized catalyst carrier 52 is proportional to the product of the square of the current flowing through the energized catalyst carrier 52 and the resistance value.

  Here, it is assumed that the temperature of the energized catalyst carrier 52 located in the central portion is higher than that of the outer peripheral portion. Even in this case, there is no difference in the current flowing through each of the energized catalyst carriers 52 thanks to the series connection described above. The resistance value of each of the energized catalyst carriers 52 is lower in the energized catalyst carrier 52 located in the center than in the outer periphery due to the NTC characteristics described above. If it does so, the Joule heat which generate | occur | produces in the electricity supply catalyst support | carrier 52 located in a center part will become low compared with an outer peripheral part. That is, according to this configuration, the initial temperature difference between the energized catalyst carriers 52 is eliminated.

  Therefore, according to the electrically heated catalyst device 50 according to the present embodiment, the temperature distribution between the electrically powered catalyst carriers 52 can be kept substantially uniform even when a catalyst having NTC characteristics is used. 50 can be suitably activated.

In FIG. 5, the number of sections is set to 16, but if it is 2 or more, the benefit is more or less. The cross-sectional area of the electrically heated catalyst device 50 is not necessarily rectangular, and may be, for example, a triangle or an ellipse.
(2) 2nd Embodiment Next, the structure of the electroheating catalyst apparatus 50 which concerns on 2nd Embodiment is demonstrated using FIG. Here, FIG. 6 is a schematic cross-sectional view of the electrically heated catalyst device 50 according to the second embodiment as viewed from the front at the position L in FIG. The configuration of the internal combustion engine 40 other than the electric heating catalyst device 50 may be the same as that of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same configurations, and the detailed description thereof is omitted as appropriate. .

  As shown in FIG. 6, in the energization heating type catalyst device 50 according to the second embodiment, consideration is given to the central portion of the plurality of energized catalyst carriers 52 where the temperature is likely to rise compared to the outer peripheral portion. Specifically, the four energized catalyst carriers 52 (that is, the energized catalyst carrier 52 of No. 06 in FIG. 6) located in the central portion are connected by the cross-shaped conductive material 56 from the exhaust gas inlet side to the outlet side. Electrical connection up to. In other words, the four energized catalyst carriers 52 located in the center are electrically in parallel. And No. in FIG. No. 06 and the four No. 6 electrically integrated catalyst carriers 52 are electrically integrated. No. 06 energized catalyst carrier 52, The 07 current-carrying catalyst carrier 52 is connected in series. According to this configuration, no. No. 06 energizing catalyst carrier 52 and four Nos. No. 06 energized catalyst carrier 52, No. 6; The current flowing in each of the 07 energized catalyst carriers 52 is equal. On the other hand, the four integrated No. 4 units are electrically integrated. The cross-sectional area of the energized catalyst carrier 52 of No. 06 is No. 06. 06 or No. It is wider than that of the 07 energized catalyst carrier 52. Then, four No. 4 which became electrically integrated. The current density of the current-carrying catalyst carrier 52 of No. 06 is no. 06 or No. It is smaller than that of the energized catalyst carrier 52 of 07. Accordingly, among the plurality of energized catalyst carriers 52, the central portion where the temperature is likely to rise as compared with the outer peripheral portion (that is, the four electrically conductive catalyst carriers 52 of No. 06 which are electrically integrated) per unit cross-sectional area. The Joule heat generated in is suppressed as compared with the outer peripheral portion.

As described above, according to the electrically heated catalyst device 50 according to the present embodiment, the current density in the central portion where the temperature is likely to rise compared to the outer peripheral portion is reduced, and the temperature between the outer peripheral portion and the central portion is reduced. The balance of ascent can be improved.
(3) Third Embodiment Next, the configuration of an electrically heated catalyst device 50 according to a third embodiment will be described with reference to FIG. Here, FIG. 7 is a schematic cross-sectional view of the electrically heated catalyst device 50 according to the third embodiment when viewed from the front at the position L in FIG. The configuration of the internal combustion engine 40 other than the electric heating catalyst device 50 may be the same as that of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same configurations, and the detailed description thereof is omitted as appropriate. .

As shown in FIG. 7, in the electrically heated catalyst device 50 according to the third embodiment, as in the second embodiment, among the plurality of energized catalyst carriers 52, the central portion where the temperature is likely to rise compared to the outer peripheral portion. Consideration has been made. However, in the second embodiment, the four energized catalyst carriers 52 located in the central portion are electrically integrated by the cross-shaped conductive material 56, whereas in the present embodiment, they are located in the central portion from the beginning. The difference is that the current-carrying catalyst carrier 52 has one cross-sectional area larger than that of the outer peripheral portion. However, even in this configuration, as in the second embodiment, since the current density in the central portion where the temperature is likely to rise compared to the outer peripheral portion is reduced, the balance between the temperature rise in the outer peripheral portion and the central portion can be improved. it can.
(4) 4th Embodiment Next, the structure of the electrically-heating catalyst apparatus 50 which concerns on 4th Embodiment is demonstrated using FIG. Here, FIG. 8 is a schematic cross-sectional view of the electrically heated catalyst device 50 according to the fourth embodiment when viewed from the front at the position L in FIG. The configuration of the internal combustion engine 40 other than the electric heating catalyst device 50 may be the same as that of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same configurations, and the detailed description thereof is omitted as appropriate. .

  As shown in FIG. 8, in the electrically heated catalyst device 50 according to the fourth embodiment, as in the second embodiment, among the plurality of energized catalyst carriers 52, the central portion where the temperature is likely to rise compared to the outer peripheral portion. Consideration has been made. However, in the second embodiment, the four current-carrying catalyst carriers 52 located in the center are electrically integrated by the cross-shaped conductive material 56, whereas in the present embodiment, the four current-carrying catalyst carriers 52 are located in the center. The difference is that the temperature of the current-carrying catalyst carrier 57 is less likely to increase than that of the current-carrying catalyst carrier 52 located on the outer periphery. Specifically, the resistance values of the four energized catalyst carriers 57 located in the central part are made smaller than those of the energized catalyst carrier 52 located in the outer peripheral part. This is because the number of cells of the four energized catalyst carriers 57 located in the central part is larger than that of the energized catalyst carrier 52 located in the outer peripheral part, or four energized catalysts located in the central part. This is realized by making the porosity of the carrier 57 smaller than that of the energized catalyst carrier 52 located on the outer peripheral portion. According to this configuration, as in the second embodiment, since the resistance value of the central portion where the temperature is likely to rise compared to the outer peripheral portion is reduced, the balance of the temperature rise between the outer peripheral portion and the central portion can be improved. it can.

  In each of the above embodiments, the electrically heated catalyst device 50 is an example of the “energized heating catalyst device” according to the present invention, the positive electrode 532 is an example of the “positive electrode” according to the present invention, and the negative electrode 533 is an example of the “negative electrode” according to the present invention, the energized catalyst carrier 52 and the energized catalyst carrier 57 are examples of the “catalyst carrier” according to the present invention, and the insulating material 54 and the conductive materials 55 and 56 are the present invention. It is an example of the "partition means" concerning.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or the idea of the invention that can be read from the claims and the entire specification. A catalytic device is also included in the technical scope of the present invention.

1 is a schematic cross-sectional view showing an internal combustion engine 40 according to a first embodiment. It is typical sectional drawing at the time of seeing the electric heating type catalyst device 50 concerning a comparative example from the side. FIG. 3 is a schematic cross-sectional view of an electrically heated catalyst device 50 according to a comparative example when viewed from the front side on the exhaust gas inlet side at a position L in FIG. 2. It is typical sectional drawing at the time of seeing the electric heating type catalyst device 50 concerning a 1st embodiment from the side. FIG. 5 is a schematic cross-sectional view when the electrically heated catalyst device 50 according to the first embodiment is viewed from the front side on the exhaust gas inlet side at a position L in FIG. 4. It is typical sectional drawing at the time of seeing the electric heating type catalyst apparatus 50 concerning 2nd Embodiment from the front in the position L of FIG. It is typical sectional drawing at the time of seeing the electric heating type catalyst apparatus 50 concerning 3rd Embodiment from the front in the position L of FIG. It is typical sectional drawing at the time of seeing electrically-heating type catalyst apparatus 50 concerning a 4th embodiment from the front in position L of Drawing 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 ... Control apparatus, 40 ... Internal combustion engine, 202 ... Spark plug, 223 ... Fuel tank, 311 ... Refueling port, 224 ... Fuel sensor, 206 ... Intake pipe, 208 ... Intake valve, 209 ... Exhaust valve, 210 ... Exhaust pipe, 221 ... Air-fuel ratio sensor, 50 ... Electric heating catalyst, 532 ... Positive electrode, 533 ... Negative electrode, 52 ... Electric catalyst carrier, 54 ... Insulating material, 55 ... Conductive material, 56 ... Conductive material, 57 ... Electric catalyst carrier

Claims (5)

An electrically heated catalyst device for heating an exhaust gas purification catalyst by Joule heat,
A positive electrode and a negative electrode installed at predetermined positions of the electric heating catalyst device;
A catalyst carrier having an NTC characteristic in which the positive electrode and the negative electrode are electrically connected and the resistance value continuously decreases as the temperature rises;
The catalyst carrier is partitioned by an insulating member, and at least a part of the partitioned current path is connected in series by a conductive member, so that the current flowing through the catalyst carrier can be compared with a case where the catalyst carrier is not partitioned by the insulating member. And a partition means for lengthening the current path. The catalyst carrier is also an exhaust gas passage in the energization heating type catalyst device,
The partition means partitions the catalyst carrier so that a cross section of the exhaust gas passage is partitioned into a plurality of sections by the insulating member, and the insulating member extends along the exhaust gas passage. The electrically heated catalyst device according to claim 1, wherein the device is an electrically heated catalyst device. The partition means partitions the catalyst carrier so that a cross-sectional area of a section located closer to the center in the cross section of the exhaust gas passage is larger than that of a section closer to the outer periphery. The electrically heated catalyst device according to 1. 3. The energization heating type according to claim 2, wherein the partitioning unit partitions the catalyst carrier so that at least two partitions located near the center in the cross section of the passage of the exhaust gas are connected in parallel. Catalytic device. The said catalyst carrier is comprised so that the resistance value of the division located near the center in the cross section of the passage of the said exhaust gas may become small compared with that near the outer periphery. Electric heating type catalytic device.

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