JP2020143658A - Internal combustion engine - Google Patents

Abstract

To detect a temperature inside an electric conductive base material with a temperature sensor while ensuring electric insulation from the electric conductive base material and suppressing the temperature sensor from blocking an exhaust flow.SOLUTION: A temperature sensor 60 to detect a temperature of an electric conductive base material 41 comprises: a temperature sensitive section 61 which is extended into an inside of the outer cylinder 30 so as to position a tip 61a thereof inside the electric conductive base material 41 in a manner that penetrates into the inside of the electric conductive base material 41 from the edge section of the electric conductive base material 41 at a downstream side in an exhaust flow direction; and an insulating pipe 63 which is inserted into the electric conductive base material 41 so as to cover the inserted portion of the temperature sensitive section 61 inside the electric conductive base material 41. The temperature sensitive section 61 and the insulating pipe 63 are arranged inside the electric conductive base material 41 so as to be almost parallel to the exhaust flow direction. The length of the insulating pipe 63 from an insertion edge section 41a of the electric conductive base material 41 to the tip 63a thereof is longer than the length of the temperature sensitive section 61 from the insertion edge section 41a to the tip 61a thereof by a predetermined length and the tip 63a of the insulating pipe 63 is an open end.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. Further, when the temperature sensor is arranged inside the conductive base material, it is necessary to ensure the insulation between the temperature sensor and the conductive base material.

The present invention has been made by paying attention to such a problem, and is insulating from the conductive base material while suppressing the flow of exhaust air passing through the inside of the conductive base material from being blocked by the temperature sensor. The purpose is to detect the temperature inside the conductive base material with a temperature sensor after ensuring the above.

In order to solve the above problems, an 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 generates heat when energized. An exhaust path is provided with a catalytic converter including an electrically heated catalytic device in which a catalyst is supported on a conductive substrate and a temperature sensor for detecting the temperature of the conductive substrate. The temperature sensor extends from the mounting part to the inside of the outer cylinder and the mounting part to be attached to the outer cylinder, and one end of the conductive base material on the upstream side in the exhaust flow direction so that the tip is located inside the conductive base material. The temperature-sensitive part inserted into the conductive base material from the other side or the other end side on the downstream side in the exhaust flow direction and the temperature-sensitive part so as to cover the periphery of the portion inserted inside the conductive base material. , With an insulating tube inserted inside the conductive substrate. The temperature-sensitive part and the insulating tube are arranged inside the conductive base material substantially parallel to the exhaust flow direction, and the temperature-sensitive part of one end or the other end of the conductive base material is inserted. The distance from the insertion-side end, which is the end, to the tip of the insulating tube extending toward the opposite end is longer than the distance from the insertion-side end to the tip of the temperature-sensitive portion by a predetermined distance. Moreover, the tip of the insulating tube is an open end.

Further, the internal combustion engine according to another aspect of the present invention is provided on the outer cylinder and a conductive base material which is provided in the outer cylinder in a state of being electrically insulated from the outer cylinder and generates heat when energized. The exhaust path is provided with a catalytic converter including an electrically heated catalyst device and a temperature sensor for detecting the temperature of the conductive substrate. The temperature sensor extends from the mounting portion to the inside of the outer cylinder and the mounting portion to be mounted on the outer cylinder, and one end of the conductive base material on the upstream side in the exhaust flow direction so that the tip is arranged inside the conductive base material. Cover the periphery of the temperature-sensitive portion inserted into the conductive base material from the other end side on the portion side or the downstream side in the exhaust flow direction and the portion of the temperature-sensitive portion inserted inside the conductive base material. Is provided with an insulating tube to be inserted inside the conductive base material. The temperature-sensitive portion and the insulating pipe are arranged substantially parallel to the exhaust flow direction inside the conductive base material, and the side of one end or the other end of the conductive base material into which the temperature-sensitive portion is inserted. The tip of the insulating tube extending from the insertion side end, which is the end of the above, toward the opposite end is a closed end.

According to these aspects of the present invention, the temperature sensor suppresses the flow of exhaust air passing through the inside of the conductive base material from being blocked by the temperature sensor, and secures insulation with the conductive base material. The temperature inside the conductive substrate can be detected.

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 the first embodiment of the present invention. FIG. 2 is a diagram illustrating a catalytic converter according to the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of the catalytic converter along line III-III of FIG. FIG. 4 is an enlarged view of a main part showing the inside of the conductive base material near the tip of the thermocouple according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating a catalytic converter according to the second embodiment of the present invention. FIG. 6 is an enlarged view of a main part showing the inside of the conductive base material near the tip of the thermocouple according to the third embodiment of the present invention. FIG. 7 is a diagram illustrating a catalytic converter according to a modified example of the present invention.

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.

(First Embodiment)
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 the first 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 and an electrically heated catalyst device (EHC; Electrical) are used. It includes a Heated Catalyst) 40 and a temperature sensor 60. 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 electrically heating type catalyst device 40 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 electrically heating type catalyst device 40 described later. The insulating layer 31 is formed by the application.

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, the second connection portion 30c is formed with an insertion hole 32 for attaching the attachment portion 62 of the temperature sensor 60, which will be described later.

The electroheating type catalyst device 40 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 electroheating type catalyst device 40 is provided in the accommodating portion 30a in a state of being electrically insulated from the accommodating portion 30a.

The temperature sensor 60 is a sensor for directly detecting the temperature (catalyst bed 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 electrically heating type 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 attachment portion 62 is electrically insulated from the second connection portion 30c of the outer cylinder 30. ing. Specifically, in the present embodiment, the mounting 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 an insertion hole of a second connecting portion 30c having a female screw. By screwing it into 32, the attachment portion 62 of the temperature sensor 60 is attached to the second connection portion 30c in a state of being electrically insulated from the second connection portion 30c.

Then, in the present embodiment, the attachment portion 62 of the temperature sensor 60 is attached to the second connection portion 30c of the outer cylinder 30 in this way, and the thermocouple 61 is attached to the outer cylinder 30 from the downstream side in the exhaust flow direction with respect to the conductive base material 41. The thermocouple 61 is inserted into the inside of the unit cell 411 of the conductive base material 41 toward the upstream side in the exhaust flow direction, and the tip 61a of the thermocouple 61 is located at the center of the conductive base material 41. As described above, the thermocouple 61 is extended to the central portion inside the conductive base material 41. Further, the thermocouple 61 is arranged inside the conductive base material 41 so as to be substantially parallel to the exhaust flow direction so that the thermocouple 61 does not obstruct the flow of the exhaust.

By arranging the thermocouple 61 inside the conductive base material 41 in this way, the temperature of the conductive base material 41 can be directly detected by the thermocouple 61. Therefore, the temperature of the conductive base material 41 can be detected with high accuracy. On the other hand, when the thermocouple 61 is arranged inside the conductive base material 41, it is conductive inside the conductive base material 41 in order to ensure the insulation between the thermocouple 61 and the conductive base material 41. It is necessary to prevent the base material 41 from coming into contact with the thermocouple 61.

Therefore, in the present embodiment, as shown in FIG. 3, an insulating tube 63 formed of an electrically insulating material such as ceramic is inserted into the unit cell 411 of the conductive base material 41, and the insulating tube 63 is formed. A thermocouple 61 is passed through the inside, and an insulating tube 63 covers the periphery of the thermocouple 61. This makes it possible to prevent the conductive base material 41 from coming into contact with the thermocouple 61.

In the present embodiment, each of the end portion of the insulating pipe 63 on the upstream side in the exhaust flow direction and the end portion of the insulating pipe 63 on the downstream side in the exhaust flow direction are open ends. That is, in the present embodiment, the tip 63a of the insulating tube 63 located in the central portion inside the conductive base material 41 and the base end 63b on the opposite side of the tip 63a are each open ends.

By setting the tip 63a and the base end 63b of the insulating pipe 63 as open ends in this way, the exhaust also flows inside the insulating pipe 63, so that the conductive carbon in the exhaust is inside the insulating pipe 63. Although it is easy to adhere, since a small amount of oxygen is also contained in the exhaust gas, the conductive carbon adhering to the inside of the insulating pipe 63 is removed by the exhaust flowing inside the insulating pipe 63 in a high temperature exhaust atmosphere. Can be oxidized. Therefore, it is possible to suppress the accumulation of conductive carbon inside the insulating tube 63, so that the deposited conductive carbon forms a current path that electrically connects the conductive base material 41 and the thermocouple 61. It can be suppressed and the deterioration of the insulating property between the conductive base material 41 and the thermocouple 61 can be suppressed.

On the other hand, when the tip 63a of the insulating tube 63 is an open end, a space is provided between the conductive base 41 and the tip 61a of the thermocouple 61 when a voltage is applied to the conductive base 41. A discharge may occur and the conductive base material 41 and the thermocouple 61 may be short-circuited, resulting in deterioration of the insulating property between the conductive base material 41 and the thermocouple 61.

In order to suppress a short circuit between the conductive base material 41 and the thermocouple 61 due to such space discharge, it is effective to provide a certain space distance or more between the conductive base material 41 and the tip 61a of the thermocouple 61. Is.

Therefore, in the present embodiment, as shown in FIG. 4, the end portion of the conductive base material 41 on the side into which the thermocouple 61 is inserted (hereinafter referred to as “insertion side end portion”. In the present embodiment, the downstream side in the exhaust flow direction). The distance L2 from the insertion side end 41a of the conductive base material 41 to the tip 63a of the insulating tube 63 is longer than the distance L1 from the end) 41a to the tip 61a of the thermocouple 61. The insulating tube 63 is arranged inside the 41. That is, the length of the insulating tube 63 inside the conductive base material 41 is made longer than the length of the thermocouple 61 inside the conductive base material 41.

As a result, for example, as shown by the alternate long and short dash line in FIG. 4, the space distance l1 between the conductive base material 41 and the tip 61a of the thermocouple 61 when the distance L1 and the distance L2 are the same is obtained. In the embodiment, as shown by the broken line in FIG. 4, the space distance l2 between the conductive base material 41 and the tip 61a of the thermocouple 61 is increased by the length of the insulating tube 63 longer than the length of the thermocouple 61. Can be lengthened. Therefore, it is possible to suppress a short circuit between the conductive base material 41 and the thermocouple 61 due to space discharge, and thus it is possible to suppress deterioration of the insulating property with the conductive base material 41.

In this embodiment, the distance L3 from the tip of the thermocouple 61 to the tip of the insulating tube 63 (hereinafter referred to as “extending distance of the insulating tube 63”) is set based on the following idea.

That is, the space discharge between the conductive base material 41 and the tip 61a of the thermocouple 61 is basically conductive as long as the space distance between the conductive base material 41 and the tip 61a of the thermocouple 61 is the same. The higher the voltage applied to the base material 41, the more likely it is to occur. Therefore, in the present embodiment, the extension distance L3 of the insulating tube 63 is set based on the maximum voltage applied to the conductive substrate.

Further, the susceptibility of space discharge between the conductive base material 41 and the tip 61a of the thermocouple 61 depends on the inside of the conductive base material 41 in addition to the magnitude of the voltage applied to the conductive base material 41. It also changes depending on whether it is in an air atmosphere or an exhaust atmosphere. Specifically, the space discharge between the conductive base material 41 and the tip 61a of the thermocouple 61 tends to occur more easily when the inside of the conductive base material 41 is in an exhaust atmosphere, and further, it is conductive. The larger the flow rate of the exhaust flowing into the sex substrate 41, and by extension, the larger the flow rate of the exhaust flowing into the inside of the unit cell 411, the more likely it is to occur. Therefore, the extension distance L3 of the insulating tube 63 may be set based on the maximum voltage applied to the conductive base material and the maximum flow rate of the exhaust gas flowing into the conductive base material 41.

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 exhaust path is provided with a catalyst converter 20 including an electrically heating type catalyst device 40 in which a catalyst is supported on 41 and a temperature sensor 60 for detecting the temperature of the conductive base material 41.

The temperature sensor 60 extends from the mounting portion 62 to be attached to the outer cylinder 30 and the inside of the outer cylinder 30 from the mounting portion 62, and the tip 61a of the conductive base material 41 is located inside the conductive base material 41. A thermocouple 61 (temperature sensitive portion) inserted into the conductive base material 41 from the other end side on the downstream side in the exhaust flow direction, and a portion of the thermocouple 61 inserted inside the conductive base material 41. An insulating tube 63 inserted inside the conductive base material 41 is provided so as to cover the periphery.

The thermocouple 61 and the insulating tube 63 are arranged inside the conductive base material 41 substantially parallel to the exhaust flow direction, and are the insertion side which is the end of the conductive base material 41 on the side where the thermocouple 61 is inserted. From the end 41a (in the present embodiment, the end on the downstream side in the exhaust flow direction of the conductive base material 41) to the end on the opposite side (in the present embodiment, the end on the upstream side in the exhaust flow direction of the conductive base material 41). The distance L2 to the tip 63a of the insulating tube 63 extending toward the portion) is longer than the distance L1 from the insertion side end 41a to the tip 61a of the thermocouple 61, and the tip of the insulating tube 63 is longer. It is an open end.

As a result, the insulating tube 63 can prevent contact between the conductive base material 41 and the thermocouple 61, and can suppress a short circuit between the conductive base material 41 and the thermocouple 61 due to spatial discharge. Deterioration of the insulating property between the material 41 and the temperature sensor 60 can be suppressed.

Further, since the thermocouple 61 and the insulating tube 63 are arranged inside the conductive base material 41 in a state of being substantially parallel to the exhaust flow direction, they are in the middle of passing through the inside of the conductive base material 41. It is possible to prevent the exhaust flow from being blocked by the thermocouple 61 and the insulating pipe 63. Therefore, it is possible to prevent the exhaust gas from flowing into the inside of the conductive base material 41 and reduce the rate of temperature rise of the conductive base material 41, which is caused by the fact that the flow of the exhaust gas is blocked by the thermocouple 61. It is possible to suppress the deterioration of exhaust emissions.

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

Further, in the present embodiment, the insertion side end 41a of the conductive base material 41 is the lower end portion of the conductive base material 41 in the exhaust flow direction, and the attachment portion 62 of the temperature sensor 60 is the conductive base material 41. It is attached to the outer cylinder 30, that is, the second connecting portion 30c on the downstream side in the exhaust flow direction.

Therefore, a portion of the thermocouple 61 that is not inserted into the conductive base material 41, which is located between the mounting portion 62 of the temperature sensor 60 and the insertion side end portion 41a of the conductive base material 41 (hereinafter, “thermocouple 61”). The "non-insertion portion") is not exposed to the exhaust before flowing into the conductive base material 41.

If the non-inserted portion of the thermocouple 61 is arranged at a position where the exhaust before flowing into the conductive base material 41 hits (that is, on the upstream side in the exhaust flow direction from the conductive base material 41), the exhaust pulsation The thermocouple 61 vibrates under the influence, and as a result, the thermocouple 61 deteriorates, or the position (temperature measurement part) of the thermocouple 61 changes, and the temperature detection accuracy of the conductive base material 41 deteriorates. There is a risk of

Further, the heat of the exhaust gas may be taken away by the thermocouple 61, and the temperature of the exhaust gas flowing into the conductive base material 41 may decrease. Therefore, the rate of temperature rise of the conductive base material 41 decreases, the time until the catalyst activates becomes long, and the exhaust emission may deteriorate. Further, since the non-insertion portion of the thermocouple 61 blocks the flow of the exhaust flowing into the conductive base material 41, the exhaust is exhausted to the unit cell 411 of the conductive base material 41 located behind the non-insertion portion of the thermocouple 61. Is less likely to flow in. As a result, the amount of heat received by the conductive base material 41 from the exhaust per unit time decreases, the rate of temperature rise of the conductive base material 41 decreases, and the catalyst supported on the conductive base material 41 is activated. The time will be longer and the exhaust emissions may worsen.

Therefore, as in the present embodiment, the temperature sensor 60 is caused by the vibration of the thermocouple 61 by preventing the exhaust before flowing into the conductive base material 41 from hitting the non-insertion portion of the thermocouple 61. It is possible to suppress the deterioration of the durability of the conductive base material 41 and the deterioration of the temperature detection accuracy of the conductive base material 41. Further, it is possible to suppress the deterioration of the exhaust emission due to the heat being taken away by the non-insertion portion of the thermocouple 61 and the deterioration of the exhaust emission due to the obstruction of the exhaust flow by the non-insertion portion of the thermocouple 61.

Further, in the present embodiment, the tip end 63a and the base end 63b of the insulating tube 63 are open ends, respectively.

Therefore, it is possible to prevent the exhaust gas from becoming difficult to flow into the unit cell 411 into which the thermocouple 61 and the insulating pipe 63 are inserted. Further, even if the conductive carbon in the exhaust adheres to the inside of the insulating pipe 63, the conductive carbon adhering to the inside of the insulating pipe 63 can be oxidized by the exhaust flowing inside the insulating pipe 63. Therefore, it is possible to suppress the accumulation of conductive carbon inside the insulating tube 63, so that the deposited conductive carbon forms a current path that electrically connects the conductive base material 41 and the thermocouple 61. It can be suppressed and the deterioration of the insulating property between the conductive base material 41 and the thermocouple 61 can be suppressed.

Further, in the present embodiment, the tip 63a of the insulating tube 63 is located inside the conductive base material 41.

If the extension distance L3 of the insulating tube 63 is increased, it becomes easier to suppress a short circuit between the conductive base material 41 and the thermocouple 61 due to space discharge. For example, the tip 63a of the insulating pipe 63 is extended to the outside of the conductive base material 41. If the stretching distance L3 is made too long, such as by extending the length, the insulating pipe 63 may be broken and the insulating pipe 63 may be damaged. Therefore, damage to the insulating tube 63 can be suppressed by setting the stretching distance L3 so that the tip 63a of the insulating tube 63 fits inside the conductive base material 41.

(Second Embodiment)
Next, the second embodiment of the present invention will be described. In this embodiment, the catalyst converter 20 is arranged on the downstream side of the electric heating type catalyst device 40 in the exhaust flow direction so as to be adjacent to the electric heating type catalyst device 40 at a certain distance. It differs from the first embodiment in that the device 50 is further provided. Hereinafter, the differences will be mainly described.

FIG. 5 is a diagram illustrating each component of the catalytic converter 20 according to the present embodiment.

As shown in FIG. 5, the catalyst converter 20 according to the present embodiment is adjacent to the electrically heating type catalyst device 40 on the downstream side in the exhaust flow direction at a certain distance from the electrically heating type catalyst device 40. Is provided with a post-stage catalyst device 50 provided in the accommodating portion 30a. The post-stage 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 insulating layer 31 formed on the inner wall surface of the housing portion 30a so as to fill the gap between the insulating base material 51 and the accommodating portion 30a. It is a component for holding the insulating base material 51 at a predetermined position in the accommodating portion 30a. The second holding mat 52 is also made of an electrically insulating material such as alumina (Al ₂ O ₃ ).

In this way, when the base material of another catalyst device such as the insulating base material 51 is arranged on the downstream side of the conductive base material 41 in the exhaust flow direction in the accommodating portion 30a, the second connecting portion 30c To extend the thermocouple 61 of the attached temperature sensor 60 to the inside of the conductive base material 41, insert the thermocouple 61 into the insulating base material 51 from the downstream end of the insulating base material 51 in the exhaust flow direction. After passing through the inside of the insulating base material 51, it is necessary to further insert the thermocouple 61 into the conductive base material 41.

At this time, if the insulating tube 63 is arranged only inside the conductive base material 41, the thermocouple 61 is passed through the inside of the insulating base material 51, and then the thermocouple 61 is passed through the conductive base material 41. It is necessary to insert it into a specific unit cell 411 in which the insulating pipe 63 is arranged and pass it through the inside of the insulating pipe 63. However, as the diameter of the unit cell 411 of the conductive base material 41, and thus the diameter of the insulating tube 63, becomes smaller, and as the lattice becomes finer and the number of unit cells 411 increases, a thermocouple 61 is provided in the specific unit cell 411. This kind of work becomes difficult because it becomes difficult to insert.

Therefore, in the present embodiment, as shown in FIG. 5, the insulating tube 63 is extended from the inside of the conductive base material 41 to the inside of the insulating base material 51. More specifically, the base end 63b of the insulating pipe 63 is extended to the end on the downstream side in the exhaust flow direction of the insulating base material 51.

As a result, if the thermocouple 61 is inserted into the insulating base material 51 from the end on the downstream side in the exhaust flow direction of the insulating base material 51, the tip 61a of the thermocouple 61 is extended to the central part of the conductive base material 41 as it is. Therefore, the workability when inserting the thermocouple 61 into the conductive base material 41 can be improved.

According to the present embodiment described above, the catalyst converter 20 is outside so as to be adjacent to the electric heating type catalyst device 40 at a certain distance on the downstream side in the exhaust flow direction of the electric heating type catalyst device 40. A post-stage catalyst device 50 provided in the cylinder 30 and having a catalyst supported on an insulating base material 51 is further provided. The mounting portion 62 of the temperature sensor 60 is mounted on the outer cylinder 30 on the downstream side in the exhaust flow direction from the insulating base material 51, that is, the second connecting portion 30c, and the thermocouple 61 is the exhaust of the insulating base material 51. It is inserted into the insulating base material 51 from the end side on the downstream side in the flow direction, passes through the inside of the insulating base material 51, and extends to the inside of the conductive base material 41. Then, the insulating tube 63 extends from the inside of the conductive base material 41 to the inside of the insulating base material 51 so as to further cover the periphery of the portion inserted into the inside of the insulating base material 51.

As a result, if the thermocouple 61 is inserted into the insulating base material 51 from the end on the downstream side in the exhaust flow direction of the insulating base material 51, the tip 61a of the thermocouple 61 is extended to the central part of the conductive base material 41 as it is. Therefore, the workability when inserting the thermocouple 61 into the conductive base material 41 can be improved.

(Third Embodiment)
Next, a third embodiment of the present invention will be described. The present embodiment is different from the first embodiment in that the tip 63a of the insulating tube 63 is a closed end. The differences will be described below.

FIG. 6 is an enlarged view of a main part showing the inside of the conductive base material 41 near the tip 61a of the thermocouple 61 according to the present embodiment.

As shown in FIG. 6, in the present embodiment, the distance L1 from the insertion side end 41a of the conductive base material 41 to the tip 61a of the thermocouple 61 and the insulation tube from the insertion side end 41a of the conductive base material 41. The distance L2 to the tip 63a of 63 is made substantially the same, and the tip 63a of the insulating tube 63 is set as the closed end.

As a result, it is possible to prevent space discharge from occurring between the conductive base material 41 and the tip 61a of the thermocouple 61. Further, since the exhaust does not flow into the inside of the insulation pipe 63 from the tip 63a side of the insulation pipe 63, it is possible to suppress the adhesion of the conductive carbon in the exhaust to the inside of the insulation pipe 63. Therefore, the conductive carbon suppresses the formation of a current path that electrically connects the conductive base material 41 and the thermocouple 61, and the insulation between the conductive base material 41 and the thermocouple 61 deteriorates. Can be suppressed.

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 exhaust path is provided with a catalyst converter 20 including an electrically heating type catalyst device 40 in which a catalyst is supported on 41 and a temperature sensor 60 for detecting the temperature of the conductive base material 41.

The temperature sensor 60 extends from the mounting portion 62 to be attached to the outer cylinder 30 and the inside of the outer cylinder 30 from the mounting portion 62, and the conductive base material 41 is arranged so that the tip 61a is arranged inside the conductive base material 41. The thermocouple 61 (temperature sensitive part) inserted into the conductive base material 41 from the end side on the downstream side in the exhaust flow direction of the thermocouple 61, and the portion of the thermocouple 61 inserted inside the conductive base material 41. An insulating tube 63 inserted inside the conductive base material 41 is provided so as to cover the periphery.

The thermocouple 61 and the insulating tube 63 are arranged inside the conductive base material 41 substantially parallel to the exhaust flow direction, and are the insertion side which is the end of the conductive base material 41 on the side where the thermocouple 61 is inserted. The tip 63a of the insulating tube 63 extending from the end 41 to the opposite end is a closed end.

As a result, it is possible to prevent space discharge from occurring between the conductive base material 41 and the tip 61a of the thermocouple 61. Further, since the exhaust does not flow into the inside of the insulation pipe 63 from the tip 63a side of the insulation pipe 63, it is possible to suppress the adhesion of the conductive carbon in the exhaust to the inside of the insulation pipe 63. Therefore, the conductive carbon suppresses the formation of a current path that electrically connects the conductive base material 41 and the thermocouple 61, and the insulation between the conductive base material 41 and the thermocouple 61 deteriorates. Can be suppressed.

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.

Further, in the first embodiment and the second embodiment described above, the base end 63b of the insulating tube 63 may be a closed end provided with a hole capable of inserting the thermocouple 61.

Further, in the above-mentioned first embodiment, the attachment portion 62 of the temperature sensor 60 is attached to the second connection portion 30c of the outer cylinder 30, but as shown in FIG. 7, for example, the attachment portion 62 of the temperature sensor 60 is outside. 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 so as to be attached to the first connection portion 30b of the cylinder 30, and the thermocouple 61 is exhaust flow from the attachment portion 62. The thermocouple 61 is passed through the unit cell 411 of the conductive base material 41 toward the downstream side in the direction so that the tip 61a of the thermocouple 61 is located at the center of the conductive base material 41. It may be extended to the central part of the inside of the. Then, the periphery of the thermocouple 61 may be covered with an insulating tube 63.

At this time, as in the first embodiment, the tip 63a of the insulating tube 63 is set to the open end, and the insertion side end 41a of the conductive base material 41 (in the example shown in FIG. 7, the conductive base material 41 is exhausted). The distance L2 from the insertion-side end 41a of the conductive base material 41 to the tip 63a of the insulating tube 63 is longer than the distance L1 from the end on the upstream side in the flow direction) to the tip 61a of the thermocouple 61. By arranging the insulating tube 63 inside the conductive base material 41, contact between the conductive base material 41 and the thermocouple 61 can be prevented, and a short circuit between the conductive base material 41 and the thermocouple 61 due to spatial discharge can be suppressed. can do.

Further, as in the third embodiment, the distance L1 from the insertion side end 41a of the conductive base material 41 to the tip 61a of the thermocouple 61 and the tip of the insulating tube 63 from the insertion side end 41a of the conductive base 41 If the distance L2 to 63a is substantially the same and the tip 63a of the insulating tube 63 is a closed end, contact between the conductive base material 41 and the thermocouple 61 can be prevented, and the conductive base material 41 and the thermocouple due to space discharge can be prevented from contacting each other. It is possible to prevent a short circuit with the pair 61.

Further, in the example shown in FIG. 7, the base end 63b of the insulating tube 63 may be used as an open end to promote the oxidation of the conductive carbon adhering to the inside of the insulating tube 63, or the base end 63b of the insulating tube 63 may be promoted. The conductive carbon may be prevented from adhering to the inside of the insulating tube 63 as a closed end provided with a hole capable of inserting the thermocouple 61.

30 Outer cylinder 40 Electric heating type catalyst device 41 Conductive base material 50 Post-stage catalyst device 51 Insulation base material 60 Temperature sensor 61 Thermocouple (temperature sensitive part)
62 Mounting part

Claims (9)

With the outer cylinder
An electrically heating type catalyst device, which is provided in the outer cylinder in a state of being electrically insulated from the outer cylinder and in which a catalyst is supported on a conductive base material that generates heat when energized.
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
The mounting part to be mounted on the outer cylinder and
One end side of the conductive base material on the upstream side in the exhaust flow direction or the other side on the downstream side in the exhaust flow direction so that the tip extends from the mounting portion to the inside of the outer cylinder and the tip is located inside the conductive base material. A temperature-sensitive part inserted into the conductive base material from the end side,
An insulating tube inserted into the conductive base material so as to cover the periphery of the temperature-sensitive portion inserted inside the conductive base material.
With
The temperature-sensitive portion and the insulating tube are arranged inside the conductive base material substantially parallel to the exhaust flow direction.
Of the insulating tube extending from the insertion side end portion, which is the end portion of the one end portion or the other end portion of the conductive base material to which the temperature sensitive portion is inserted, toward the opposite end portion. The distance to the tip is longer than the distance from the insertion side end to the tip of the temperature sensitive portion by a predetermined distance, and the tip of the insulating tube is an open end.
Internal combustion engine. The insertion side end is the other end of the conductive substrate.
The mounting portion is mounted on the outer cylinder on the downstream side in the exhaust flow direction with respect to the conductive base material.
The internal combustion engine according to claim 1. The base end of the insulating pipe opposite to the tip of the insulating pipe is an open end.
The internal combustion engine according to claim 2. The catalytic converter
The catalyst was provided in the outer cylinder on the downstream side in the exhaust flow direction of the electroheating catalyst device so as to be adjacent to the electroheating catalyst device at a certain distance, and the catalyst was supported on an insulating base material. Further equipped with a post-stage catalyst device,
The mounting portion is mounted on the outer cylinder on the downstream side in the exhaust flow direction with respect to the insulating base material.
The temperature-sensitive portion is inserted into the inside of the insulating base material from the end side on the downstream side in the exhaust flow direction of the insulating base material, passes through the inside of the insulating base material, and is inside the conductive base material. Has been extended to
The insulating tube extends from the inside of the conductive base material to the inside of the insulating base material so as to further cover the periphery of the portion inserted into the inside of the insulating base material.
The internal combustion engine according to claim 2 or 3. The insertion-side end is one end of the conductive substrate.
The base end of the insulating pipe opposite to the tip of the insulating pipe is a closed end.
The internal combustion engine according to claim 1. The tip of the insulating tube is located inside the conductive substrate.
The internal combustion engine according to any one of claims 1 to 5. The predetermined distance is set based on the maximum voltage applied to the conductive substrate.
The internal combustion engine according to any one of claims 1 to 6. The predetermined distance is set based on the maximum voltage applied to the conductive base material and the maximum flow rate of the exhaust gas flowing into the conductive base material.
The internal combustion engine according to any one of claims 1 to 6. With the outer cylinder
An electrically heating type catalyst device, which is provided in the outer cylinder in a state of being electrically insulated from the outer cylinder and in which a catalyst is supported on a conductive base material that generates heat when energized.
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
The mounting part to be mounted on the outer cylinder and
One end side of the conductive base material on the upstream side in the exhaust flow direction or the downstream side in the exhaust flow direction so as to extend from the mounting portion to the inside of the outer cylinder and to arrange the tip inside the conductive base material. A temperature-sensitive part inserted into the conductive base material from the other end side,
An insulating tube inserted into the conductive base material so as to cover the periphery of the temperature-sensitive portion inserted inside the conductive base material.
With
The temperature-sensitive portion and the insulating tube are arranged inside the conductive base material substantially parallel to the exhaust flow direction.
Of the insulating tube extending from the insertion side end portion, which is the end portion of the one end portion or the other end portion of the conductive base material to which the temperature sensitive portion is inserted, toward the opposite end portion. The tip is a closed end,
Internal combustion engine.

Images