JP2020143649A - Internal combustion engine - Google Patents

Abstract

To detect a temperature inside a base material with a temperature sensor while suppressing the same from blocking an exhaust flow passing through inside the base material.SOLUTION: A temperature sensor 60 to detect a temperature of an electric conductive base material 41 comprises: a base end section 62 which is installed on an outer cylinder 30 at a downstream side of an insulating base material 51 in an exhaust flow direction; and a temperature sensitive section 61 which is extended from the base edge section 62 into an inside of the outer cylinder 30 so as to position a tip thereof inside the electric conductive base material 41 in a manner that penetrates through the insulating base material 51 from an edge section of the insulating base material 51 at the downstream side in the exhaust flow direction and penetrates into the inside of the electric conductive base material 41 from the edge section of the electric conductive base material 41 at the downstream side in the exhaust flow direction. The temperature sensitive section 61 is arranged almost parallel to the exhaust flow direction in the electric conductive base material 41 and the insulating base material 51.SELECTED DRAWING: Figure 2

Description

The present invention relates to an internal combustion engine.

In Patent Document 1, as a conventional internal combustion engine, a temperature sensor for indirectly detecting the temperature of a conductive base material is formed on an insulating base material arranged on the downstream side in the exhaust flow direction of the conductive base material. The temperature sensor attached to the catalytic converter is disclosed so as to be arranged inside the provided accommodating hole.

JP-A-2016-200069

However, in the conventional internal combustion engine described above, since the temperature sensor is arranged outside the conductive base material, the temperature detection accuracy of the conductive base material may decrease. On the other hand, it is conceivable to arrange the temperature sensor inside the conductive base material, but in the above-mentioned conventional internal combustion engine, the temperature sensor is attached to the catalytic converter so as to be orthogonal to the flow direction of the exhaust gas. Was there. Therefore, when the temperature sensor is arranged inside the conductive base material, the temperature sensor is arranged in the middle of the conductive base material so as to block the flow of exhaust gas. As a result, it becomes difficult for the exhaust to flow inside the conductive base material, the amount of heat received from the exhaust by the conductive base material per unit time is reduced, and the rate of temperature rise of the conductive base material may decrease.

The present invention has been made by paying attention to such a problem, and an object of the present invention is to detect the temperature inside the conductive base material by the temperature sensor while suppressing the flow of the exhaust gas from being blocked by the temperature sensor. And.

In order to solve the above problems, the internal combustion engine according to a certain aspect of the present invention is provided in the outer cylinder in a state of being electrically insulated from the outer cylinder and is electrically electrically insulated to generate heat. The first catalyst device in which the catalyst is supported on the sex substrate and the first catalyst device are provided in the outer cylinder so as to be adjacent to the first catalyst device at a certain distance on the downstream side in the exhaust flow direction of the first catalyst device, and have insulating properties. The exhaust path is provided with a catalyst converter including a second catalyst device in which a catalyst is supported on the base material and a temperature sensor for detecting the temperature of the conductive base material. The temperature sensor has a base end portion attached to the outer cylinder on the downstream side in the exhaust flow direction from the insulating base material, and extends from the base end portion to the inside of the outer cylinder, and the tip is located inside the conductive base material. As such, it is inserted into the inside of the insulating base material from the end on the downstream side in the exhaust flow direction of the insulating base material, passes through the inside of the insulating base material, and from the end on the downstream side in the exhaust flow direction of the conductive base material. A temperature-sensitive portion inserted inside the conductive base material is provided, and the temperature-sensitive portion is arranged inside the conductive base material and the insulating base material substantially parallel to the exhaust flow direction.

According to this aspect of the present invention, the temperature inside the conductive base material can be detected by the temperature sensor while suppressing the flow of the exhaust gas from being blocked by the temperature sensor.

FIG. 1 is a schematic configuration diagram of an internal combustion engine and an electronic control unit that controls an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a catalytic converter according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of the catalytic converter along line III-III of FIG. FIG. 4A is a diagram illustrating a catalytic converter according to a first comparative example different from the present invention. FIG. 4B is a diagram illustrating a catalytic converter according to a second comparative example different from the present invention. FIG. 5 is a view of the inside of the accommodating portion of the catalytic converter of the first comparative example as viewed from the upstream side in the exhaust flow direction. FIG. 6 is a diagram illustrating a flow velocity of exhaust gas flowing inside the catalytic converter according to the embodiment of the present invention. FIG. 7 is a diagram showing an optimum position for attaching the base end portion of the temperature sensor when the outer cylinder is viewed from the downstream side in the exhaust flow direction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, similar components are given the same reference number.

FIG. 1 is a schematic configuration diagram of an internal combustion engine 100 and an electronic control unit 200 that controls an internal combustion engine 100 according to an embodiment of the present invention.

The internal combustion engine 100 includes an engine body 1 that internally compresses and self-ignites and burns fuel to generate power for driving a vehicle or the like. The engine body 1 introduces a combustion chamber 2 formed in each cylinder, an electronically controlled fuel injection valve 3 for injecting fuel into each combustion chamber 2, and intake air into each combustion chamber 2. Including an intake manifold 4 for discharging exhaust from each combustion chamber 2 and an exhaust manifold 5 for discharging exhaust from each combustion chamber 2.

Each fuel injection valve 3 is connected to the common rail 16 via a fuel supply pipe 15. The common rail 16 is connected to the fuel tank 18 via an electronically controlled fuel pump 17 whose discharge amount can be changed. The fuel stored in the fuel tank 18 is supplied into the common rail 16 by the fuel pump 17. The fuel supplied into the common rail 16 is supplied to the fuel injection valve 3 via each fuel supply pipe 15.

The intake manifold 4 is connected to the outlet of the compressor 7a of the exhaust turbocharger 7 via the intake duct 6. The inlet of the compressor 7a is connected to the air cleaner 9 via the intake pipe 8. The intake pipe 8 is provided with an air flow meter 211 for detecting the amount of intake air. An electrically controlled throttle valve 10 driven by a step motor is arranged in the intake duct 6. A cooling device 11 for cooling the intake air flowing in the intake duct 6 is arranged around the intake duct 6.

The exhaust manifold 5 is connected to the inlet of the exhaust turbine 7b of the exhaust turbocharger 7. The outlet of the exhaust turbine 7b is connected to the exhaust pipe 19 provided with the catalytic converter 20. The exhaust manifold 5 and the intake manifold 4 are connected to each other via an EGR passage 12 for exhaust gas recirculation (hereinafter referred to as “EGR”). An electronically controlled EGR control valve 13 is arranged in the EGR passage 12. Around the EGR passage 12, an EGR cooler 14 for cooling the EGR gas flowing in the EGR passage 12 is arranged.

The catalyst converter 20 is a device for removing harmful substances in the exhaust gas discharged from the engine main body 1 and then discharging the exhaust gas to the outside air. The outer cylinder 30, the first catalyst device 40, and the second catalyst are used. The device 50 and the temperature sensor 60 are provided. Each component of the catalyst converter 20 will be described later with reference to FIG.

The electronic control unit 200 is composed of a digital computer and is connected to each other by a bidirectional bus 201. ROM (read-only memory) 202, RAM (random access memory) 203, CPU (microprocessor) 204, input port 205, and output port. It is equipped with 206.

Output signals from the above-mentioned air flow meter 211 and temperature sensor 60 are input to the input port 205 via the corresponding AD converters 207. Further, the output voltage of the load sensor 212 that generates an output voltage proportional to the depression amount L of the accelerator pedal 220 is input to the input port 205 via the corresponding AD converter 207. Further, as a signal for calculating the engine rotation speed N, an output signal of the crank angle sensor 213 that generates an output pulse every time the crankshaft of the engine body 1 rotates by, for example, 15 ° is input to the input port 205. In this way, the output signals of various sensors necessary for controlling the internal combustion engine 100 are input to the input port 205.

Each control component such as a fuel injection valve 3, a step motor for driving the throttle valve 10, an EGR control valve 13, and a fuel pump 17 is electrically connected to the output port 206 via a corresponding drive circuit 208.

The electronic control unit 200 outputs a control signal for controlling each control component from the output port 206 based on the output signals of various sensors input to the input port 205.

FIG. 2 is a diagram illustrating each component of the catalytic converter 20 according to the present embodiment. FIG. 3 is a schematic cross-sectional view of the catalytic converter 20 along the line III-III of FIG.

The outer cylinder 30 is typically a case made of a metal such as stainless steel or a non-metal such as ceramic, and is formed between the accommodating portion 30a and the first connection formed on the upstream side of the accommodating portion 30a in the exhaust flow direction. A portion 30b and a second connecting portion 30c formed on the downstream side in the exhaust flow direction with respect to the accommodating portion 30a are provided. In the present embodiment, the outer cylinder 30 is connected to the exhaust pipe 19 so as to be substantially horizontal.

The accommodating portion 30a is a portion for accommodating the first catalyst device 40 and the second catalyst device 50 inside, and its inner diameter is made larger than the inner diameter of the exhaust pipe 19. The inner wall surface of the accommodating portion 30a is coated with an electrically insulating material such as glass in order to electrically insulate the outer cylinder 30 and the conductive base material 41 of the first catalyst device 40 described later. The insulating layer 31 is formed by the above.

The first connection portion 30b is a portion formed so that the inner diameter thereof gradually expands from the inner diameter of the exhaust pipe 19 toward the inner diameter of the accommodating portion 30a along the exhaust flow direction, and the front end portion thereof is the exhaust pipe 19 Connected to.

The second connection portion 30c is a portion formed so that the inner diameter thereof gradually narrows from the inner diameter of the accommodating portion 30a toward the inner diameter of the exhaust pipe 19 along the exhaust flow direction, and the rear end portion thereof is the exhaust pipe. Connected to 19. In the present embodiment, an insertion hole 32 for attaching the base end portion of the temperature sensor 60 is formed at a portion located on the upper side in the gravity direction of the second connection portion 30c and on the outer side in the radial direction with respect to the exhaust pipe 19. There is. The reason for this will be described later.

The first catalyst device 40 is an electric heating type catalyst device (EHC; Electrical Heated Catalyst), and includes a conductive base material 41, a first holding mat 42, and a pair of electrodes 43.

The conductive base material 41 is formed of a material that generates heat when energized, such as silicon carbide (SiC) or molybdenum disilicate (MoSi ₂ ). As shown in FIG. 3, the conductive base material 41 is formed with a plurality of passages (hereinafter referred to as “unit cells”) 411 having a lattice shape (or honeycomb shape) in cross section along the flow direction of the exhaust gas. A catalyst is supported on the surface of each unit cell 411. The catalyst to be supported on the conductive base material 41 is not particularly limited, and a catalyst necessary for obtaining desired exhaust gas purification performance can be appropriately selected from various catalysts and supported on the conductive base material 41. it can.

The first holding mat 42 is provided between the conductive base material 41 and the accommodating portion 30a so as to fill the gap between the conductive base material 41 and the accommodating portion 30a, and accommodates the conductive base material 41 in the accommodating portion. It is a component for holding in a predetermined position within 30a. The first holding mat 42 is formed of an electrically insulating material such as alumina (Al ₂ O ₃ ).

The pair of electrodes 43 are components for applying a voltage to the conductive base material 41, and one end thereof is electrically insulated from the conductive base material 41 in a state of being electrically insulated from the accommodating portion 30a. It is connected to the. The other end of one electrode 43a of the pair of electrodes 43 is connected to the positive terminal of the power supply 44 such as a battery, and the other end of the other electrode 43b is connected to the negative terminal of the power supply 44. By applying a voltage to the conductive base material 41 through the pair of electrodes 43, an electric current flows through the conductive base material 41 to generate heat of the conductive base material 41, and the catalyst supported on the conductive base material 41 is generated. It is heated.

As described above, the first catalyst device 40 is provided in the accommodating portion 30a in a state of being electrically insulated from the accommodating portion 30a.

The second catalyst device 50 is provided in the accommodating portion 30a so as to be adjacent to the first catalyst device 40 on the downstream side in the exhaust flow direction of the first catalyst device 40. The second catalyst device 50 includes an insulating base material 51 and a second holding mat 52.

The insulating base material 51 is formed of an electrically insulating material such as cordierite. Similar to the conductive base material 41, the insulating base material 51 is also formed with a plurality of unit cells (not shown) having a lattice shape (or honeycomb shape) in cross section along the exhaust flow direction, and each unit is formed. A catalyst is supported on the surface of the cell. The catalyst to be supported on the insulating base material 51 is not particularly limited, and a catalyst necessary for obtaining desired exhaust gas purification performance can be appropriately selected from various catalysts and supported on the insulating base material 51. it can. The catalyst supported on the insulating base material 51 may be the same as or different from the catalyst supported on the conductive base material 41.

The second holding mat 52 is provided between the insulating base material 51 and the accommodating portion 30a so as to fill the gap between the insulating base material 51 and the accommodating portion 30a, and accommodates the insulating base material 51 in the accommodating portion. It is a component for holding in a predetermined position in 30a. The second holding mat 52 is also made of an electrically insulating material such as alumina (Al ₂ O ₃ ).

The temperature sensor 60 is a sensor for directly detecting the temperature of the conductive base material 41 by the thermocouple 61. Based on the temperature detected by the temperature sensor 60, the electronic control unit 200 performs energization control on the conductive base material 41, failure determination of the first catalyst device 40, and the like.

As shown in FIG. 2, the temperature sensor 60 according to the present embodiment is attached to the second connection portion 30c in a state where the base end portion 62 thereof is electrically insulated from the second connection portion 30c of the outer cylinder 30. ing. Specifically, in the present embodiment, the base end portion 62 of the temperature sensor 60 is an insulating nipple having a male screw on the outer peripheral surface, and this nipple is inserted into a second connecting portion 30c having a female screw. By screwing into the hole 32, the base end portion 62 of the temperature sensor 60 is attached to the second connecting portion 30c in a state of being electrically insulated from the second connecting portion 30c.

Then, in the present embodiment, the base end portion 62 of the temperature sensor 60 is attached to the second connecting portion 30c of the outer cylinder 30 in this way, and the thermocouple 61 is exhausted from the conductive base material 41 and the insulating base material 51. The thermocouple 61 is inserted from the downstream side in the direction into the inside of the outer cylinder 30 so as to extend from the base end portion 62 toward the upstream side in the exhaust flow direction to the inside of the conductive base material 41. Specifically, the thermocouple 61 is inserted into the unit cell of the insulating base material 51 from the downstream end of the insulating base material 51 in the exhaust flow direction, passed through the inside of the insulating base material 51, and then the thermocouple is subjected to the thermocouple. The pair 61 is further inserted into the unit cell 411 of the conductive base material 41 from the downstream end of the conductive base material 41 in the exhaust flow direction (see FIG. 3), and the tip 61a of the thermocouple 61 is inserted into the conductive base material 41. I try to extend it to the center of the inside of. Then, the thermocouple 61 is arranged inside the conductive base material 41 and the insulating base material 51 so as to be substantially parallel to the exhaust flow direction so that the thermocouple 61 does not obstruct the flow of the exhaust. There is.

As described above, in the present embodiment, the thermocouple 61 is inserted into the outer cylinder 30 from the downstream side in the exhaust flow direction with respect to the conductive base material 41 and the insulating base material 51. The reason will be described below.

When the base end portion 62 of the temperature sensor 60 is attached to the outer cylinder 30 and the thermocouple 61 is extended from the base end portion 62 to the inside of the conductive base material 41, the temperature sensor 60 is attached to the second connection portion 30c as in the present embodiment. In addition to the method of attaching the base end portion 62 of the above to extend the thermocouple 61 from the base end portion 62 toward the upstream side in the exhaust flow direction to the inside of the conductive base material 41, for example, the third shown in FIG. 4A. 1 As in the comparative example, the base end portion 62 of the temperature sensor 60 is attached to the first connection portion 30b, and the thermocouple 61 is inserted into the outer cylinder 30 from the upstream side in the exhaust flow direction of the conductive base material 41. Then, a method is conceivable in which the thermocouple 61 is extended from the base end portion 62 toward the downstream side in the exhaust flow direction to the inside of the conductive base material 41. Further, as in the second comparative example shown in FIG. 4B, the base end portion 62 of the temperature sensor 60 is attached to the accommodating portion 30a, and the thermocouple 61 is inserted between the conductive base material 41 and the insulating base material 51 to form the outer cylinder 30. A method is conceivable in which the thermocouple 61 is inserted into the inside of the conductive base material 41 from the base end portion 62 toward the upstream side in the exhaust flow direction.

However, in the case of the first comparative example shown in FIG. 4A, the following problems occur as a comparison with the present embodiment.

That is, in the case of the first comparative example shown in FIG. 4A, since the thermocouple 61 is exposed to the exhaust gas before flowing into the conductive base material 41 and the insulating base material 51, the influence of the exhaust pulsation as compared with the present embodiment. The thermocouple 61 is likely to vibrate due to the strong reception.

Therefore, the thermocouple 61 may be deteriorated and the temperature sensor 60 may be damaged. That is, the durability of the temperature sensor 60 may be deteriorated. Further, the vibration of the thermocouple 61 may change the position of the thermocouple 61 (temperature measurement site), which may deteriorate the detection accuracy of the temperature (catalyst bed temperature) of the conductive base material 41. Furthermore, when the thermocouple 61 vibrates, the thermocouple 61 may come into contact with the inner wall surface of the first connecting portion 30b and also come into contact with the conductive base material 41 inside the conductive base material 41. As a result, the insulating property between the conductive base material 41 and the outer cylinder 30 may deteriorate.

Further, since the thermocouple 61 is hit by the exhaust before flowing into the conductive base material 41 and the insulating base material 51, the heat of the exhaust is easily taken away by the thermocouple 61 as compared with the present embodiment, and the conductive group. The temperature of the exhaust flowing into the material 41 and the insulating base material 51 may decrease. Therefore, the rate of temperature rise of the conductive base material 41 and the insulating base material 51 decreases, the time until the catalyst activates becomes long, and the exhaust emission may deteriorate.

Further, as shown in FIG. 5, when the inside of the accommodating portion 30a is viewed from the upstream side in the exhaust flow direction, in the first comparative example shown in FIG. 4A, the flow of exhaust gas flowing into the conductive base material 41 by the thermocouple 61. Is blocked, so that it becomes difficult for exhaust gas to flow into a part of the unit cells 411 of the conductive base material 41 located behind the thermocouple 61 (downstream side in the exhaust flow direction). Then, since the amount of heat received from the exhaust by the conductive base material 41 per unit time is reduced, the time until the heating rate of the conductive base material 41 decreases and the catalyst supported on the conductive base material 41 is activated. May become longer and exhaust emissions may worsen.

Further, also in the case of the second comparative example shown in FIG. 4B, the following problems occur as a comparison with the present embodiment.

That is, also in the case of the second comparative example shown in FIG. 4B, when the inside of the accommodating portion 30a is viewed from the upstream side in the exhaust flow direction, the flow of the exhaust gas flowing into the insulating base material 51 is blocked by the thermocouple 61. Therefore, it becomes difficult for the exhaust gas to flow into some unit cells of the insulating base material 51 located behind the thermocouple 61. As a result, as in the first comparative example, the amount of heat received from the exhaust by the insulating base material 51 per unit time is reduced, so that the rate of temperature rise of the insulating base material 51 is reduced and the insulating base material 51 is supported on the insulating base material 51. It takes a long time for the catalyst to be activated, which may worsen the exhaust emission.

Further, in the case of the second comparative example shown in FIG. 4B, it is necessary to form the insertion hole 32 for attaching the base end portion 62 of the temperature sensor 60 to the insulating layer 31 formed on the inner wall surface of the accommodating portion 30a. .. That is, it is necessary to attach the base end portion 62 of the temperature sensor 60 to the accommodating portion 30a through the insulating layer 31.

Therefore, even if a seal or the like is applied, the conductive carbon contained in the exhaust penetrates and accumulates in the gap (that is, the insertion hole 32) between the base end portion 62 of the temperature sensor 60 and the insulating layer 31, and is conductive. The carbon may form a current path that electrically connects the conductive base material 41 and the outer cylinder 30. As a result, the insulating property between the conductive base material 41 and the outer cylinder 30 may deteriorate.

On the other hand, as in the present embodiment, the base end portion 62 of the temperature sensor 60 is attached to the second connection portion 30c, and the thermocouple 61 is a conductive base material from the base end portion 62 toward the upstream side in the exhaust flow direction. By extending to the inside of the 41, the thermocouple 61 is not exposed to the exhaust before flowing into the conductive base material 41 and the insulating base material 51. Therefore, it is possible to suppress the vibration of the thermocouple 61 due to the exhaust pulsation, and it is possible to suppress the heat being taken away by the thermocouple 61.

Therefore, the durability of the temperature sensor 60 deteriorates due to the vibration of the thermocouple 61, the temperature detection accuracy of the conductive base material 41 deteriorates, and the insulation property between the conductive base material 41 and the outer cylinder 30 deteriorates. Can be suppressed. In addition, deterioration of exhaust emissions due to heat being taken away by the thermocouple 61 can be suppressed.

Further, since the thermocouple 61 does not block the flow of the exhaust flowing into the conductive base material 41 and the insulating base material 51, it becomes difficult for the exhaust to flow into the conductive base material 41 and the insulating base material 51. It is possible to suppress a decrease in the rate of temperature rise of the conductive base material 41 and the insulating base material 51. Therefore, it is possible to suppress deterioration of exhaust emissions due to the thermocouple 61 blocking the flow of exhaust gas flowing into the conductive base material 41 and the insulating base material 51.

Further, since it is not necessary to attach the base end portion 62 of the temperature sensor 60 to the accommodating portion 30a through the insulating layer 31, there is a gap between the base end portion 62 of the temperature sensor 60 and the insulating layer 31 (that is, the insertion hole 32). It is possible to suppress deterioration of the insulating property between the conductive base material 41 and the outer cylinder 30 due to the intrusion and accumulation of conductive carbon in the outer cylinder 30.

Next, the reason why the base end portion 62 of the temperature sensor 60 is attached to the portion located on the upper side in the gravity direction of the second connecting portion 30c and on the radial side outside the exhaust pipe 19 will be described.

Liquid water in which water vapor in the exhaust is condensed may collect on the inner wall surface of the outer cylinder 30. The liquid water basically collects on the inner wall surface of the outer cylinder 30 on the lower side in the direction of gravity. Therefore, when the base end portion 62 of the temperature sensor 60 is attached to the lower side in the gravity direction of the second connecting portion 30c, the liquid water is less than the case where the base end portion 62 is attached to the upper side in the gravity direction as in the present embodiment. It becomes easy to enter the insertion hole 32. As a result, a current path that electrically connects the conductive base material 41 and the outer cylinder 30 is formed by the liquid water accumulated on the inner wall surface on the lower side in the direction of gravity of the outer cylinder 30 and the liquid water that has entered the insertion hole 32. There is a risk that the insulation between the conductive base material 41 and the outer cylinder 30 will deteriorate.

Therefore, by attaching the base end portion 62 of the temperature sensor 60 to the upper side in the gravity direction of the second connecting portion 30c, the deterioration of the insulating property between the conductive base material 41 and the outer cylinder 30 due to such liquid water is deteriorated. Can be suppressed.

Further, as shown in FIG. 6, the flow velocity of the exhaust gas flowing through the portion of the outer cylinder 30 located radially outside the exhaust pipe 19 is lower than the flow velocity of the mainstream exhaust gas flowing inside the exhaust pipe 19. Tend to do. Therefore, by providing the base end portion 62 of the temperature sensor 60 at a portion of the outer cylinder 30 located radially outside the exhaust pipe 19, the base end portion 62 of the temperature sensor 60 is exposed to the mainstream of exhaust gas. It is possible to suppress an increase in the temperature of the base end portion 62. Therefore, for example, deterioration of the base end portion 62 of the temperature sensor 60 due to a difference in thermal expansion between the outer cylinder 30 and the base end portion 62 of the temperature sensor 60 can be suppressed, and deterioration of the durability of the temperature sensor 60 can be suppressed. it can.

Therefore, when the outer cylinder 30 is viewed from the downstream side in the exhaust flow direction, the portion located on the upper side in the gravity direction of the second connecting portion 30c and on the radial side in the exhaust pipe 19 as shown in FIG. 7 is located. It can be said that this is the optimum position for mounting the base end portion 62 of the temperature sensor 60.

The internal combustion engine 100 according to the present embodiment described above is provided in the outer cylinder 30 in a state of being electrically insulated from the outer cylinder 30, and is a conductive base material that generates heat when energized. The first catalyst device 40 in which the catalyst is carried on the 41 and the first catalyst device 40 are provided in the outer cylinder 30 so as to be adjacent to the first catalyst device 40 at a certain distance on the downstream side in the exhaust flow direction. The exhaust path is provided with a catalyst converter 20 including a second catalyst device 50 in which a catalyst is supported on an insulating base material 51 and a temperature sensor 60 for detecting the temperature of the conductive base material 41. The temperature sensor 60 has a base end portion 62 attached to the outer cylinder 30 on the downstream side in the exhaust flow direction from the insulating base material 51, and extends from the base end portion 62 to the inside of the outer cylinder 30, and the tip thereof is a conductive base material. The conductive base material 41 is inserted into the inside of the insulating base material 51 from the downstream end of the insulating base material 51 in the exhaust flow direction so as to be located inside the insulating base material 51, and passes through the inside of the insulating base material 51. The thermocouple 61 (temperature-sensitive portion) inserted into the conductive base material 41 from the end on the downstream side in the exhaust flow direction of the thermocouple 61 includes the conductive base material 41 and the insulating base material 51. It is arranged substantially parallel to the exhaust flow direction inside the.

As a result, the exhaust before flowing into the conductive base material 41 and the insulating base material 51 does not hit the thermocouple 61, and the thermocouple 61 is substantially parallel to the exhaust flow direction. And because it is arranged inside the insulating base material 51, the flow of exhaust before flowing into the conductive base material 41 and the insulating base material 51 and the inside of the conductive base material 41 and the insulating base material 51 can be seen. It is possible to prevent the flow of exhaust while passing through from being blocked by the thermocouple 61. Therefore, it is possible to prevent the exhaust gas from flowing into the conductive base material 41 and the insulating base material 51 and the rate of temperature rise of the conductive base material 41 and the insulating base material 51 from decreasing. Deterioration of exhaust emissions due to the obstruction of the exhaust flow by the thermocouple can be suppressed.

Further, since the exhaust before flowing into the conductive base material 41 and the insulating base material 51 does not hit the thermocouple 61, it is possible to suppress the thermocouple 61 from vibrating due to the exhaust pulsation, and heat is applied to the thermocouple 61. It can be suppressed from being robbed. Therefore, the durability of the temperature sensor 60 deteriorates due to the vibration of the thermocouple 61, the insulation between the conductive base material 41 and the outer cylinder 30 deteriorates, and the temperature detection accuracy of the conductive base material 41 deteriorates. Can be suppressed. In addition, deterioration of exhaust emissions due to heat being taken away by the thermocouple 61 can be suppressed.

Further, since it is not necessary to attach the base end portion 62 of the temperature sensor 60 to the outer cylinder 30 through the insulating layer 31, there is a gap between the base end portion 62 of the temperature sensor 60 and the insulating layer 31 (that is, the insertion hole 32). It is possible to suppress deterioration of the insulating property between the conductive base material 41 and the outer cylinder 30 due to the intrusion and accumulation of conductive carbon in the outer cylinder 30.

Further, since the thermocouple 61 is arranged inside the conductive base material 41, the temperatures of the conductive base material 41 and the insulating base material 51 can be detected with high accuracy.

Further, in the present embodiment, the outer cylinder 30 is provided in the exhaust pipe 19 (exhaust passage) so as to be substantially horizontal, and the base end portion 62 of the temperature sensor 60 is located on the upper portion of the outer cylinder 30 in the gravity direction. It is attached. Therefore, it is possible to prevent liquid water in which water vapor in the exhaust gas is condensed from entering the insertion hole 32 for attaching the base end portion 62 of the temperature sensor 60 to the outer cylinder 30. Therefore, it is possible to suppress the formation of a current path that electrically connects the conductive base material 41 and the outer cylinder 30 by the liquid water, and the insulation between the conductive base material 41 and the outer cylinder 30 is deteriorated. Can be suppressed.

Further, in the present embodiment, the outer cylinder has a portion whose inner diameter is larger than the inner diameter of the exhaust pipe 19 (exhaust passage), and the base end portion 62 of the temperature sensor 60 is larger than the exhaust pipe 19 of the outer cylinder 30. It is attached to a portion larger than the inner diameter of the exhaust pipe 19 located on the outer side in the radial direction.

Inside the outer cylinder 30, the flow velocity of the exhaust gas flowing through the portion located radially outside the exhaust pipe 19 tends to be lower than the mainstream of the exhaust gas flowing inside the outer cylinder 30. Therefore, by providing the base end portion 62 of the temperature sensor 60 at a portion of the outer cylinder 30 located radially outside the exhaust pipe 19, it is possible to suppress the temperature rise of the base end portion 62 of the temperature sensor 60. it can. Therefore, for example, deterioration of the base end portion 62 of the temperature sensor 60 due to a difference in thermal expansion between the outer cylinder 30 and the base end portion 62 of the temperature sensor 60 can be suppressed, and deterioration of the durability of the temperature sensor 60 can be suppressed. it can.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. Absent.

For example, in the above embodiment, the internal combustion engine 100 is configured so that the fuel is compressed and self-ignited and burned by the engine body 1, but the internal combustion engine 100 is configured so that the fuel is spark-ignited and burned by the engine body 1. Is also good. Further, the exhaust pipe 19 may be provided with an exhaust purification device other than the catalyst converter 20, such as a particulate filter or another catalyst device.

30 Outer cylinder 40 1st catalyst device 41 Conductive base material 50 2nd catalyst device 51 Insulation base material 60 Temperature sensor 61 Thermocouple (temperature sensitive part)
62 base end

Claims (1)

With the outer cylinder
A first catalyst device provided in the outer cylinder in a state of being electrically insulated from the outer cylinder, and a catalyst is supported on a conductive base material that generates heat when energized.
A second catalyst device provided in the outer cylinder so as to be adjacent to the first catalyst device at a certain distance on the downstream side in the exhaust flow direction of the first catalyst device, and the catalyst is supported on an insulating base material. When,
A temperature sensor for detecting the temperature of the conductive substrate and
An internal combustion engine equipped with a catalytic converter in the exhaust path.
The temperature sensor
A base end portion attached to the outer cylinder on the downstream side in the exhaust flow direction from the insulating base material, and
The insulating base material extends from the base end portion to the inside of the outer cylinder and the end portion of the insulating base material downstream from the end portion in the exhaust flow direction of the insulating base material so that the tip is located inside the conductive base material. A temperature-sensitive portion that is inserted inside, passes through the inside of the insulating base material, and is inserted into the inside of the conductive base material from an end portion on the downstream side in the exhaust flow direction of the conductive base material.
With
The temperature-sensitive portion is arranged inside the conductive base material and the insulating base material substantially parallel to the exhaust flow direction.
Internal combustion engine.

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