Electric heating type catalyst device for supercharged engine

Abstract

To provide an electric heating type catalyst device for a supercharged engine capable of suppressing short-circuit that can occur due to adhesion of particulate matters and condensation water.SOLUTION: An electric heating type catalyst device for a supercharged engine is a catalyst device 200 installed in an exhaust passage 13 of a vehicle with a turbocharger. The catalyst device 200 includes a case 240 that accommodates a catalyst carrier 210 generating heat through electric conduction. An introduction pipe 170 is connected to an exhaust outlet of the turbocharger. The catalyst device 200 includes a connection pipe 300 that connects the introduction pipe 170 and the case 240 and constitutes a double pipe. In the catalyst device 200, a labyrinth part 330 that communicates with the exhaust passage 13 through a gap between an introduction end part 171 that is an end part on the exhaust downstream side of the introduction pipe 170 and an insulation part 243 of the case 240 is provided between the insulation part 243 and the connection pipe 300.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electrically heated catalyst device for a supercharged engine that is applied to a vehicle equipped with a supercharged engine. [Background technology]

[0002] Electrically heated catalyst devices are known that heat the catalyst carried by passing electricity through the catalyst carrier to generate heat. The catalyst carrier is attached in an electrically insulated state to the tubular case that houses the catalyst carrier. In such electrically heated catalyst devices, there is a risk of a short circuit between the catalyst carrier and the case due to particulate matter or condensed water contained in the exhaust gas adhering to the insulating part. If a short circuit occurs, electricity will also flow through the case, reducing the efficiency of heating the catalyst.

[0003] Patent Document 1 discloses a catalytic device in which the tubes are tripled to form a labyrinth section upstream of the catalyst carrier in the exhaust flow direction. The above structure is designed to make it difficult for the exhaust to reach the insulating section unless the flow direction of the exhaust that collides with the catalyst carrier is repeatedly reversed. For this reason, the disclosed catalytic device is designed to suppress the adhesion of particulate matter and condensed water to the insulating section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-166474 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a vehicle equipped with a turbocharger, the flow of exhaust gas in the exhaust passage is different from that in a naturally aspirated vehicle. Therefore, the structure of the catalytic converter described in Patent Document 1 may not be effective enough in suppressing adhesion of particulate matter and condensed water to the insulating part. In a vehicle equipped with a turbocharger, a catalytic converter capable of suppressing short-circuiting between the catalyst carrier and the case is required. [Means for solving the problem]

[0006] The means for solving the above problems and their effects will be described below. The electrically heated catalyst device for a supercharged engine that solves the above problems is an electrically heated catalyst device for a supercharged engine that is installed in the exhaust passage of a vehicle equipped with a turbocharger. The turbocharger can discharge exhaust gas downstream by bypassing the turbine wheel by opening a wastegate valve and opening a bypass passage. An introduction pipe is connected to the exhaust outlet of the turbocharger.

[0007] This electrically heated catalyst device for a supercharged engine includes a catalyst for purifying exhaust gas, a catalyst carrier that generates heat when current is applied to heat the catalyst, an electrode that applies current to the catalyst carrier, a case that is a tube that contains the catalyst carrier, and a mat that serves as an insulator that fixes the catalyst carrier within the case. The upstream end of the case protrudes toward the upstream side of the exhaust gas beyond the upstream end of the catalyst carrier and serves as an insulating part that provides electrical insulation.

[0008] The case and the introduction pipe are connected by a connection pipe. The connection pipe has a first connection part on the exhaust upstream side and a second connection part on the exhaust downstream side. The first connection part of the connection pipe is connected from the outside to the end part of the introduction pipe on the exhaust downstream side. The second connection part of the connection pipe on the exhaust downstream side is connected from the outside to the insulating part of the case. A part of the connection pipe between the first connection part and the second connection part is radially separated from the insulating part and forms a double pipe with the insulating part.

[0009] A labyrinth portion that communicates with the exhaust passage by a gap between the exhaust downstream side end of the introduction pipe and the insulating portion of the case is provided between the insulating portion and the connecting pipe. Effect of the Invention

[0010] The electrically heated catalyst device for a supercharged engine can suppress short-circuiting between the catalyst carrier and the case. Therefore, the electrically heated catalyst device for a supercharged engine can allow the electrodes to efficiently heat the catalyst carrier. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a vehicle engine to which one embodiment of an electrically heated catalyst device for a supercharged engine is applied. [Diagram 2] FIG. 2 is a cross-sectional view of a turbocharger and a catalytic converter according to an embodiment. [Diagram 3] FIG. 3 is an enlarged view of a labyrinth portion in the catalyst device of the embodiment. [Figure 4] FIG. 4 is an enlarged view of a labyrinth portion in the catalytic converter shown in Patent Document 1. In FIG. [Diagram 5] FIG. 5 is an enlarged view of a labyrinth portion in a catalytic converter according to a modified example. [Figure 6] FIG. 6 is an enlarged view of a labyrinth portion in a catalytic converter according to another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a catalyst device 200 which is one embodiment of an electrically heated catalyst device for a supercharged engine will be described with reference to Figs. <Engine 10 Configuration> First, the configuration of a vehicle engine 10 to which a catalytic converter 200 is applied will be described with reference to FIG.

[0013] As shown in Fig. 1, an engine 10 includes an intake passage 11, a cylinder 12, an exhaust passage 13, a bypass passage 14, a turbocharger 100, and a catalytic converter 200. The turbocharger 100 includes a compressor housing 110, a turbine housing 120, a compressor wheel 130, a connecting shaft 140, and a turbine wheel 150. The turbine housing 120 includes a wastegate valve 160. The opening and closing of the wastegate valve 160 is controlled by an actuator 162 via a link mechanism 161.

[0014] The intake passage 11 introduces intake air from outside the engine 10. The cylinders 12 are connected to the intake passage 11. The cylinders 12 mix fuel with the intake air and burn it. The exhaust passage 13 is connected to the cylinders 12. The exhaust passage 13 discharges exhaust gas from the cylinders 12. The catalytic device 200 is installed midway through the exhaust passage 13. The catalytic device 200 purifies the exhaust gas flowing through the exhaust passage 13.

[0015] The turbocharger 100 is provided across the intake passage 11 and the exhaust passage 13. The compressor housing 110 of the turbocharger 100 is attached midway through the intake passage 11. The turbine housing 120 is attached to a portion of the exhaust passage 13 upstream of the catalytic device 200. The compressor housing 110 houses a compressor wheel 130. The compressor wheel 130 is connected to a first end of a connecting shaft 140. The turbine housing 120 houses a turbine wheel 150. The turbine wheel 150 is connected to a second end of the connecting shaft 140. That is, the compressor wheel 130 is connected to the turbine wheel 150 via the connecting shaft 140.

[0016] When the turbine wheel 150 rotates due to the flow of exhaust gas inside the turbine housing 120, the compressor wheel 130 rotates together with the turbine wheel 150 via the connecting shaft 140. As the compressor wheel 130 rotates, the intake air inside the compressor housing 110 is compressed. At this time, the bypass passage 14 is closed by the wastegate valve 160.

[0017] When the intake air inside the compressor housing 110 is not compressed, i.e., when the turbine wheel 150 is not rotated by the flow of exhaust gas, the actuator 162 opens the wastegate valve 160 via the link mechanism 161. When the wastegate valve 160 is opened, the exhaust gas flows into the exhaust passage 13 via the bypass passage 14. That is, by opening the wastegate valve 160 and opening the bypass passage 14, the turbocharger 100 can discharge the exhaust gas downstream, bypassing the turbine wheel 150.

[0018] <Configuration of turbocharger 100> Next, the configuration of the turbocharger 100 will be described with reference to FIG. As shown in FIG. 2, the turbine housing 120 of the turbocharger 100 defines two scroll passages 121, an accommodation space 122, an exhaust outlet 123, and two bypass passages 14 as spaces through which exhaust gas flows. Note that FIG. 2 illustrates one bypass passage 14. The scroll passage 121 extends in an arc shape so as to surround the turbine wheel 150. The upstream end of the scroll passage 121 is connected to the exhaust passage 13 upstream of the turbine housing 120. The downstream end of the scroll passage 121 is connected to the accommodation space 122. The accommodation space 122 is a space in which the turbine wheel 150 is located. The accommodation space 122 is connected to the exhaust outlet 123. The downstream end of the exhaust outlet 123 is connected to an introduction pipe 170 downstream of the turbine housing 120. The introduction pipe 170 is a part of the exhaust passage 13. Each bypass passage 14 connects the scroll passage 121 and the exhaust outlet 123. The wastegate valve 160 is provided at the outlet of the bypass passage 14. The bypass passage 14 is closed by the wastegate valve 160. In other words, when the wastegate valve 160 is open, the bypass passage 14 bypasses the exhaust upstream side and the exhaust downstream side of the turbine wheel 150.

[0019] <Configuration of the catalytic converter 200> Next, a description will be given of the configuration of the catalyst device 200. In Fig. 2, an axis C1 is shown as a straight line along the central axis of the catalyst device 200.

[0020] As shown in Fig. 2, the catalytic device 200 includes a catalyst carrier 210 that supports a catalyst for purifying exhaust gas. The catalyst carrier 210 has a cylindrical outer shape with an axis C1 as the central axis. The catalyst carrier 210 is a porous body. For example, the catalyst carrier 210 is a structure having a honeycomb structure in which a plurality of passages extending in the exhaust gas flow direction are defined. The catalyst supported by the catalyst carrier 210 is, for example, a three-way catalyst.

[0021] The catalytic device 200 includes a case 240, which is a tube that houses the catalyst carrier 210. The case 240 is a tube made of a metal material. For example, the case 240 is made of stainless steel. The axis C1 coincides with a straight line along the central axis of the case 240.

[0022] The end face on the exhaust upstream side of the catalyst carrier 210 housed in the case 240 is referred to as the catalyst upstream end 211. The portion of the case 240 on the exhaust upstream side, separated by the catalyst upstream end 211, is referred to as the end 242, and the portion on the exhaust downstream side is referred to as the housing section 241. The end 242 protrudes further upstream in the exhaust than the catalyst upstream end 211. The surface of the end 242 is covered with an insulator. An insulating layer is formed on the end 242 by the insulator covering the entire surface of the end 242. In this manner, the end 242 serves as the insulating section 243.

[0023] The catalytic converter 200 includes a pair of electrodes 230 for passing electricity through the catalyst carrier 210. An electrode insertion hole 231 into which the electrode 230 is inserted is opened in the housing portion 241 of the case 240. The electrode insertion hole 231 is closed by an electrode holding portion 232. The electrode 230 is connected to the catalyst carrier 210. A voltage is applied between the pair of electrodes 230, so that a current flows through the catalyst carrier 210. When a current flows through the catalyst carrier 210, the catalyst carrier 210 generates heat due to the electrical resistance of the catalyst carrier 210. That is, the catalyst carrier 210 is a material that generates heat according to the electrical resistance when electricity is passed through it. For example, the catalyst carrier 210 is a ceramic material made of silicon carbide. The electrode 230 connected to the catalyst carrier 210 protrudes outside the case 240 through the electrode insertion hole 231. The electrode holding portion 232 is an insulator with low electrical conductivity. The electrode holder 232 supports the electrode 230 so that no current flows through the case 240 .

[0024] The catalyst device 200 includes a mat 220 that fixes the catalyst carrier 210 to a housing portion 241 in a case 240. The mat 220 covers the surface of the catalyst carrier 210 that corresponds to the side surface of the cylinder. The mat 220 is an insulator with low electrical conductivity. For example, the mat 220 is an inorganic fiber whose main component is alumina. Since the catalyst carrier 210 is covered by the mat 220, electricity is prevented from flowing through the case 240 when electricity is applied to the catalyst carrier 210.

[0025] <Connection between turbocharger 100 and catalytic converter 200> Next, the connection between the turbocharger 100 and the catalytic converter 200 will be described. As shown in FIG. 3, the case 240 and the introduction pipe 170 are connected by a connection pipe 300. The connection pipe 300 has a first connection part 310 on the exhaust upstream side and a second connection part 320 on the exhaust downstream side. The first connection part 310 of the connection pipe 300 is connected from the outside to the introduction end part 171, which is the end part on the exhaust downstream side of the introduction pipe 170. The second connection part 320 on the exhaust downstream side of the connection pipe 300 is connected from the outside to the exhaust downstream side of the insulating part 243 of the case 240. The part between the first connection part 310 and the second connection part 320 of the connection pipe 300 is radially separated from the insulating part 243 and forms a double pipe with the insulating part 243. The space between the connection pipe 300 and the insulating part 243, which is a double pipe, is the labyrinth part 330. The labyrinth part 330 is connected to the exhaust passage 13 through a gap between the introduction end part 171 and the insulating part 243 of the case 240.

[0026] 3, an inner diameter R1 of the lead-in pipe 170 is equal to an inner diameter R2 of the insulating portion 243 of the case 240. In addition, a distance L1 between the case 240 and the lead-in pipe 170 at the closest portion is set to be equal to or greater than the shortest distance capable of insulation at the maximum voltage supplied to the catalyst carrier 210.

[0027] <Action of this embodiment> 4, Patent Document 1 describes a triple-pipe structure in which an inlet pipe 170, a connection pipe 300, and an insulating section 243 form a triple pipe. In the triple-pipe structure, a portion of the exhaust gas that bounces off the catalyst upstream end 211 of the catalyst carrier 210 enters between the inlet pipe 170 and the insulating section 243, and is guided into the labyrinth section 330.

[0028] In a vehicle equipped with turbocharger 100, exhaust gas discharged from wastegate valve 160 collides obliquely with catalyst upstream end 211. As a result, in a vehicle equipped with turbocharger 100, more exhaust gas bounces off catalyst upstream end 211 than in a naturally aspirated vehicle. Therefore, as shown in the area surrounded by a dashed line in Fig. 4, exhaust gas tends to flow into the area between lead-in pipe 170 and insulating section 243 that forms the triple pipe structure, i.e., into the inlet of labyrinth section 330. The exhaust gas that flows into the inlet of labyrinth section 330 in this way is blocked by lead-in pipe 170 and does not return to exhaust passage 13, and is instead guided into the inside of labyrinth section 330.

[0029] 3, when the connecting pipe 300 and the insulating section 243 form a double pipe, the exhaust gas is not guided into the labyrinth section 330 due to being blocked by the inlet pipe 170 as in the triple pipe structure. Therefore, in the catalytic device 200, the exhaust gas that has bounced off the catalyst upstream end 211 is less likely to be guided into the labyrinth section 330. This enables the catalytic device 200 to suppress adhesion of particulate matter and condensed water to the insulating section 243 due to the intrusion of the exhaust gas.

[0030] The wastegate valve 160 is often opened when the engine is started. It is known that particulate matter in the exhaust increases during a cold start of the engine. As described above, even when the wastegate valve 160 is open, the catalytic device 200 can suppress the intrusion of exhaust into the labyrinth portion 330. Therefore, the catalytic device 200 can suppress the particulate matter in the exhaust, which increases during a cold start, from adhering to the insulating portion 243.

[0031] <Effects of this embodiment> (1) If adhesion of particulate matter and condensed water to the insulating portion 243 can be suppressed, a path through which electricity flows can be suppressed from being formed in the insulating portion 243. That is, the catalytic device 200 can suppress a short circuit between the catalyst carrier 210 and the case 240. Therefore, in the catalytic device 200, the electrode 230 can cause the catalyst carrier 210 to efficiently generate heat.

[0032] (2) When the inner diameter R2 of the insulating part 243 is smaller than the inner diameter R1 of the introduction pipe 170, the exhaust gas tends to directly enter the labyrinth part 330. On the other hand, when the inner diameter R2 of the insulating part 243 is equal to or larger than the inner diameter R1 of the introduction pipe 170, the exhaust gas tends to not directly enter the labyrinth part 330.

[0033] In the catalytic converter 200, the inner diameter R2 of the insulating part 243 in the case 240 is the same as the inner diameter R1 of the introduction pipe 170 and is equal to or greater than the inner diameter R1 of the introduction pipe 170. This enables the catalytic converter 200 to suppress adhesion of particulate matter and condensed water to the insulating part 243 due to the intrusion of exhaust gas.

[0034] (3) In the catalytic converter 200, the inner diameter R2 of the insulating portion 243 in the case 240 is the same as the inner diameter R1 of the lead-in pipe 170. When the wastegate valve 160 is closed, the exhaust gas flowing out from the turbine wheel 150 becomes a swirling flow and reaches the case 240 along the lead-in pipe 170. When the inner diameter R2 of the insulating portion 243 and the inner diameter R1 of the lead-in pipe 170 are the same, the exhaust gas forming a swirling flow along the inner circumferential surface of the lead-in pipe 170 flows along the inner circumferential surface of the insulating portion 243 while maintaining the swirling flow. This allows the insulating portion 243 to be efficiently heated by the exhaust gas. By heating the insulating portion 243 by the exhaust gas, the temperature of the connecting pipe 300 becomes lower relative to the insulating portion 243. This allows the particulate matter attached to the insulating portion 243 to easily move to the inner circumferential surface of the connecting pipe 300 by thermophoresis, thereby suppressing the attachment of the particulate matter to the insulating portion 243.

[0035] According to the above-described configuration that can prevent a path through which electricity flows from being formed in the insulating portion 243, the catalyst device 200 can prevent a short circuit between the catalyst carrier 210 and the case 240. (4) In the catalytic converter 200, the distance L1 between the case 240 and the lead-in pipe 170 at the closest portion is set to be equal to or greater than the shortest distance that allows insulation at the maximum voltage supplied to the catalyst carrier 210. By narrowing the gap between the lead-in pipe 170 and the insulating section 243, the amount of exhaust gas flowing into the labyrinth section 330 through the gap between the lead-in pipe 170 and the insulating section 243 can be reduced. However, if the gap between the lead-in pipe 170 and the insulating section 243 is narrowed, a short circuit may occur between the lead-in pipe 170 and the insulating section 243. Therefore, in the catalytic converter 200, the distance L1 between the case 240 and the lead-in pipe 170 at the closest portion is set to be equal to or greater than the shortest distance that allows insulation at the maximum voltage supplied to the catalyst carrier 210. By having such a structure, the catalytic converter 200 can further suppress the occurrence of a short circuit between the case 240 and the lead-in pipe 170.

[0036] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0037] The case 240 constituting the catalytic converter 200 may be made of an insulating material. In this case, the end portion 242 does not need to be covered with an insulating layer. The case 240 constituting the catalytic converter 200 may be connected to the turbine housing 120 by a pipe formed by integrating the introduction pipe 170 and the connection pipe 300 .

[0038] The shape of the connecting pipe 300 connected to the case 240 constituting the catalytic converter 200 can be changed. For example, the inner surface of the connecting pipe 300 may be curved. For example, the outer surface of the connecting pipe 300 may be curved.

[0039] The inner diameter R2 of the insulating part 243 in the catalytic converter 200 and the inner diameter R1 of the lead-in pipe 170 do not necessarily have to be the same. For example, the inner diameter R2 of the insulating part 243 and the inner diameter R1 of the lead-in pipe 170 may be substantially the same. When the inner diameter R2 of the insulating part 243 and the inner diameter R1 of the lead-in pipe 170 are substantially the same, the exhaust gas that bounces back at the catalyst upstream end 211 is less likely to be guided into the labyrinth part 330 compared to when the inner diameter R2 of the insulating part 243 and the inner diameter R1 of the lead-in pipe 170 are different. This allows the catalytic converter 200 to suppress adhesion of particulate matter and condensed water to the insulating part 243 due to the intrusion of exhaust gas.

[0040] 5, the inner diameter R2 of the insulating part 243 in the catalyst device 200 may be larger than the inner diameter R1 of the introduction pipe 170. In that case, it is sufficient to design it after confirming that the occurrence of a short circuit between the catalyst carrier 210 and the case 240 is suppressed.

[0041] 6, the inner diameter R2 of the insulating portion 243 in the catalyst device 200 may be less than the inner diameter R1 of the introduction pipe 170. In that case, it is sufficient to design it after confirming that the occurrence of a short circuit between the catalyst carrier 210 and the case 240 is suppressed. [Explanation of symbols]

[0042] 10...engine, 11...intake passage, 12...cylinder, 13...exhaust passage, 14...bypass passage, 100...turbocharger, 110...compressor housing, 120...turbine housing, 121...scroll passage, 122...accommodation space, 123...exhaust outlet, 130...compressor wheel, 140...connecting shaft, 150...turbine wheel, 160...wastegate valve, 161...link mechanism, 162...actuator, 170...inlet pipe, 171...inlet end, 200...catalyst device, 210...catalyst carrier, 211...catalyst upstream end, 220...mat, 230...electrode, 231...electrode insertion hole, 232...electrode holding portion, 240...case, 241...accommodation portion, 242...end, 243...insulating portion, 300...connecting pipe, 310...first connecting portion, 320...second connecting portion, 330...labyrinth portion

Claims

1. An electrically heated catalyst device for a turbocharged engine is installed in an exhaust passage of a vehicle equipped with a turbocharger, which is capable of discharging exhaust gas downstream by opening a wastegate valve and opening a bypass passage, A catalyst for purifying exhaust gas; A catalyst carrier that generates heat by energization to heat the catalyst; An electrode for passing current through the catalyst support; A case that is a tube that houses the catalyst carrier; a mat as an insulator for fixing the catalyst carrier in the case, an end portion of the case on the upstream side of the exhaust gas flow protrudes toward the upstream side of the exhaust gas flow more than an end portion of the catalyst carrier on the upstream side of the exhaust gas flow and serves as an insulating portion that provides electrical insulation; an inlet pipe connected to an exhaust outlet of the turbocharger; a connecting pipe in which a first connecting portion on the upstream side of the exhaust gas is connected to an end portion of the introduction pipe on the downstream side of the exhaust gas from the outside, and a second connecting portion on the downstream side of the exhaust gas is connected to the insulating portion of the case from the outside, and a portion between the first connecting portion and the second connecting portion is radially separated from the insulating portion to form a double pipe with the insulating portion, A labyrinth portion that communicates with the exhaust passage by a gap between the exhaust downstream side end of the introduction pipe and the insulating portion of the case is provided between the insulating portion and the connecting pipe. Electrically heated catalytic converter for turbocharged engines.

2. The inner diameter of the insulating portion of the case is equal to or larger than the inner diameter of the introduction pipe.

2. The electrically heated catalyst device for a supercharged engine according to claim 1.

3. The inner diameter of the insulating portion of the case is the same as the inner diameter of the introduction pipe.

2. The electrically heated catalyst device for a supercharged engine according to claim 1.

4. The inner diameter of the insulating portion of the case and the inner diameter of the introduction pipe are substantially the same.

2. The electrically heated catalyst device for a supercharged engine according to claim 1.

5. The distance between the case and the introduction pipe at the closest portion is set to be equal to or greater than the shortest distance that allows insulation at the maximum voltage supplied to the catalyst carrier.

2. The electrically heated catalyst device for a supercharged engine according to claim 1.

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