JP2010270653A - Exhaust emission purifying system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely avoid an electric leak due to the inflow of exhaust emissions containing condensed water without decreasing the effect of an electric heating type catalyst device. <P>SOLUTION: In a hybrid vehicle 10, the ECU 100 executes EHC electrical leak prevention control. In the control, the ECU 100 controls a selector valve 500, when an EHC 400 is energized, and temperature of the EHC 400 is less than 100°C, while the position of a valve body 520 of the selector valve 500 is controlled to a bypass position. When the valve body position is controlled to the bypass position, exhaust emission is directed to a bypass passage 217, on the upstream side of the EHC 400. On the other hand, in the bypass passage 217, an adsorbent 218 adsorbing the moisture in the exhaust emissions is placed, and the exhaust emission directed to the bypass passage 217 is supplied to the EHC 400 in a state where moisture such as condensed water is decreased due to the action of the adsorbent 218. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to the technical field of an exhaust gas purification system for an internal combustion engine.

  In a configuration including an electrically heated catalyst device as this type of system, a device for preventing electric leakage of the electrically heated catalyst device has been proposed (see, for example, Patent Document 1). According to the exhaust gas purification apparatus for an internal combustion engine disclosed in Patent Document 1, an upstream catalyst carrier having a heater function and a downstream catalyst carrier are provided, and a part of the exhaust gas is diverted to the downstream catalyst carrier while bypassing the upstream catalyst carrier. In the configuration in which the temperature increase of the downstream catalyst carrier is promoted by providing a bypass passage that leads, the positive electrode of the heater in the upstream catalyst carrier is disposed above the bypass passage, so that moisture condensed in the bypass passage is transferred to the positive electrode. It is said that it is possible to prevent electric leakage due to outflow.

  In addition, some hybrid vehicles have been proposed in which EHC is energized when the engine is started due to a decrease in SOC during EV travel (see, for example, Patent Document 2).

  In addition, in a configuration that does not have an electrically heated catalyst device, an HC adsorbent capable of adsorbing moisture is provided, and an exhaust gas is allowed to flow into the HC adsorbent during cold start (for example, Patent Documents). 3).

JP-A-8-210217 Japanese Patent Laid-Open No. 10-288028 Japanese Patent Laid-Open No. 8-14035

  The burned gas contains water as a component. For example, in an internal combustion engine that has been in a cold state for a long period of time, condensed water is likely to be generated particularly in the exhaust passage. Accordingly, in a configuration including an electrically heated catalyst device, for example, when the electrically heated catalyst device is energized to promote catalyst warm-up when the internal combustion engine is started after a relatively long non-operation period, etc. Furthermore, there is a possibility that the exhaust gas containing not only this condensed water flows from the exhaust passage on the upstream side of the electrically heated catalyst device into the electrically heated catalyst device, thereby causing electric leakage.

  When power leakage occurs, or when power is supplied in spite of the possibility of leakage, first of all, power resources may be wasted. Secondly, due to the fact that the vehicle body (body or chassis) or the exhaust passage can be charged, for example, when the driver contacts the body during driving, a kind of electric shock occurs to some extent. there is a possibility.

  According to the device disclosed in Patent Document 1, although the electrode installation position has been devised in consideration of the possibility of electric leakage, the occurrence of electric leakage caused mainly by condensed water generated in the exhaust passage is this type. There are limits to what can be prevented only by hardware measures. In addition, if the electric heating type catalyst device is frequently restricted for the purpose of simply avoiding electric leakage, the emission reduction at the start of the internal combustion engine will be insufficient, and the electric heating type catalyst device will be installed. The significance of doing it will fade. In addition, the devices of Patent Documents 2 and 3 have no suggestion about such a leakage, and it must be said that it is impossible to prevent this type of leakage.

  As described above, it is difficult for various conventional apparatuses including the above-described prior art to avoid leakage due to inflow of exhaust gas including condensed water while sufficiently ensuring the exhaust gas purification performance required for the electrically heated catalyst device. There is a technical problem. The present invention has been made in view of such problems, and provides an exhaust gas purification system for an internal combustion engine that can reliably avoid electric leakage due to inflow of exhaust gas containing condensed water without reducing the effectiveness of the electrically heated catalyst device. The task is to do.

  In order to solve the above-described problems, an exhaust gas purification system for an internal combustion engine according to the present invention is an exhaust gas purification system for an internal combustion engine mounted on a vehicle, and is installed in a main exhaust passage of the internal combustion engine and generates heat when energized. An electrically heated catalyst device, a bypass passage provided on the upstream side of the electrically heated catalyst device so as to bypass a predetermined bypassed section in the main exhaust passage, and water in the exhaust gas installed in the bypass passage Adsorbing means capable of trapping, a switching valve capable of opening and closing the bypass passage, and first control means for controlling the electric heating catalyst device so that the energization is performed when starting the internal combustion engine, A specifying means for specifying the temperature of the electrically heated catalyst device, and so that the exhaust gas is led to the bypass passage when the specified temperature is less than a reference value. Characterized by comprising a second control means for controlling the switching valve.

  The internal combustion engine according to the present invention means an engine capable of converting the combustion of fuel into mechanical power. For example, the fuel type (for example, gasoline, light oil, alcohol, alcohol mixed fuel or natural gas), the fuel There are no particular limitations on the physical, mechanical, or electrical configuration, such as the supply mode, fuel combustion mode, intake / exhaust system configuration, and cylinder arrangement. The vehicle according to the present invention is a vehicle that can include the internal combustion engine as at least one power source, and as long as the vehicle is used, the practical aspects may vary.

  The electric heating type catalyst device according to the present invention warms up the catalyst device by the function as a catalyst device installed in the main exhaust passage of the internal combustion engine to purify the exhaust gas of the internal combustion engine and the heat generation action accompanying energization. It is a concept encompassing an exhaust emission control device having at least a function as a heater, and within the concept, its physical, mechanical, electrical, magnetic and chemical configurations are not limited at all.

  For example, the electrically heated catalyst device may have a structure in which the catalyst device itself has a heater function, for example, because the catalyst carrier is composed of an electric resistor having a relatively high electric resistance, or the heater is a catalyst carrier. The catalyst carrier may be arranged close to the outer peripheral part or the upstream / downstream part of the catalyst and warm up the catalyst carrier by conduction heat or radiant heat. In addition, the electric heating type catalyst device may appropriately include various power sources such as a battery, a power supply circuit, a power supply wiring, and various controllers and control devices for controlling the supplied power as practical aspects. Is not necessarily installed in the main exhaust passage.

  In the exhaust gas purification system for an internal combustion engine according to the present invention, the bypassed section corresponding to a part of the main exhaust passage (preferably further downstream of the exhaust manifold) on the upstream side of the electrically heated catalyst device is In the interior, it is bypassed by a bypass passage communicating with the main exhaust passage. In this bypass passage, moisture in the exhaust gas led to the bypass passage can be collected (Note that “collection” is a comprehensive concept including various practical aspects such as adsorption, filtration, capture or desorption. There is a suction means.

  On the other hand, the bypass passage is configured to be appropriately opened or closed by the action of the switching valve. The switching valve is preferably configured so that the bypassed section of the main exhaust passage is closed as the bypass passage is opened, but for example, experimentally, empirically, theoretically in advance. Or, open the bypass passage within an allowable range where it has been determined that there is no practical problem based on simulation or the like (as will be described later, the condensed water in the exhaust does not at least significantly promote the electric leakage of the electrically heated catalyst device). Sometimes a part of the exhaust may be led to the bypassed section.

  Here, according to the exhaust gas purification apparatus for an internal combustion engine according to the present invention, at the time of operation, for example, one or a plurality of CPUs (Central Processing Units), MPUs (Micro Processing Units), various processors or various controllers, or even ROM (Read Only Memory), RAM (Random Access Memory), various storage units such as buffer memory or flash memory, etc. as appropriate, various processing units such as single or multiple ECUs (Electronic Controlled Units), various controllers, By means of the first control means that can take the form of various computer systems such as a microcomputer device, the electrically heated catalyst device is controlled so as to be energized at the start of the internal combustion engine, preferably at the cold start. The electrically heated catalyst device is configured to warm up the catalyst device by Joule heat generated by energization, and by energizing in this way, it becomes possible to promote warming up of the catalyst device.

  At this time, it is not always necessary for the first control means to perform such energization when the internal combustion engine is started. For example, the internal combustion engine is restarted after a sufficiently short interval at which the catalyst temperature does not significantly decrease. Such warming may be stopped or prohibited during a warm start including the case where the

  On the other hand, when the internal combustion engine is in a stop state before starting, particularly when it is physically stopped (that is, even when the fuel supply is stopped, even physical movement caused by inertia or inertia occurs). When the exhaust gas stays in the exhaust passage, condensed water is likely to be generated due to heat deprived from the pipe wall of the exhaust passage in the course of the natural cooling of the internal combustion engine. At this time, the condensed water generated on the upstream side of the electrically heated catalyst device reaches the downstream electrically heated catalyst device when an exhaust flow is formed in the exhaust passage when the internal combustion engine is started. As a result, the electrically heated catalyst device is exposed to a moist atmosphere, and the possibility of causing electric leakage is relatively high.

  Therefore, in order to avoid such a problem, in the exhaust gas purification system for an internal combustion engine according to the present invention, for example, one or a plurality of CPUs, MPUs, various processors or various controllers, or further ROM, RAM, buffer memory or flash memory The temperature of the electrically heated catalyst device can be suitably included in various processing units such as a single or a plurality of ECUs, various controllers, various computer systems such as a microcomputer device, etc. Is identified. In addition, “specific” according to the present invention includes detection, calculation, derivation, selection, acquisition, identification, and the like, and is a concept that broadly encompasses the determination as reference information for control. The purpose is not limited in any way.

  When the temperature of the electrically heated catalyst device is specified in this way, for example, one or a plurality of CPUs, MPUs, various processors or various controllers, or various storage means such as ROM, RAM, buffer memory, flash memory, etc. The switching valve is appropriately controlled by second control means that can take various forms such as various processing units such as a single unit or a plurality of ECUs, various controllers or various computer systems such as a microcomputer device. That is, the second control means controls the switching valve so that the exhaust gas is guided to the bypass passage described above when the specified temperature is lower than the reference value.

  As described above, adsorption means is installed in the bypass passage, and at least the condensed water contained in the exhaust gas led to the bypass passage is converted into the electric power of the electrically heated catalyst device. The total amount or ideally the entire amount is adsorbed to the extent that it does not significantly affect the mechanical insulation state. As a result, the exhaust gas guided to the electrically heated catalyst device via the bypass passage is discharged downstream without adversely affecting the electrical insulation state of the electrically heated catalyst device to a practical disadvantage. The Therefore, according to the present invention, it is necessary to limit or prohibit energization of the electrically heated catalyst device in consideration of the possibility of electric leakage due to wet exhaust gas containing condensed water flowing into the electrically heated catalyst device. Disappears. That is, it is possible to avoid electric leakage due to condensed water without reducing the effectiveness of the electrically heated catalyst device.

  The second control means does not necessarily need to close the bypassed section of the main exhaust passage when introducing the exhaust into the bypass passage. That is, based on experimental, empirical, theoretical, or simulation, the distribution ratio that does not affect the electrical insulation state of the electrically heated catalyst device, the allowable flow rate of the bypassed section, etc. are determined in advance. In such a case, a part of the exhaust gas may be guided to the bypassed section based on the distribution ratio and the allowable flow rate. In view of the configuration in which the adsorbent is arranged in the bypass passage, the bypass passage section of the main exhaust passage may have a lower flow resistance than the bypass passage. In the configuration that can be derived, it is possible to avoid an excessive increase in the back pressure of the internal combustion engine, and it is possible to reliably avoid electric leakage of the electrically heated catalyst device without affecting the power performance of the internal combustion engine.

  The term “less than” according to the present invention is a concept that can be easily replaced with “below” depending on the setting of the reference value, and in which region the reference value is included affects the essence of the present invention. Don't give.

  In one aspect of the exhaust gas purification system for an internal combustion engine according to the present invention, the reference value is a temperature of 100 ° C. or higher.

  The boiling point of water is approximately 100 ° C. under normal atmospheric pressure, and if the temperature of the electrically heated catalyst device is 100 ° C. or higher, even if exhaust containing condensed water is led to the electrically heated catalyst device, Since the evaporation is promoted in the heated catalyst device, the possibility of electrical leakage is significantly reduced. That is, according to this aspect, it is possible to efficiently avoid electric leakage of the electrically heated catalyst device.

  In addition, since the temperature of the specified electrically heated catalyst device is not necessarily the lowest temperature of the electrically heated catalyst device, a margin may be given to the safe side to some extent from the viewpoint of eliminating the possibility of leakage. For example, the reference value may be 100 ° C. + α.

  In another aspect of the exhaust gas purification system for an internal combustion engine according to the present invention, the second control means controls the switching valve so that the exhaust gas is guided to the bypass passage during a deceleration fuel cut period of the internal combustion engine.

  In the deceleration fuel cut period in which the fuel supply is stopped during the deceleration period of the vehicle, the internal combustion engine is in a state of inertia and physically operating, and no combusted exhaust as a source of condensed water is generated. That is, the exhaust gas of the internal combustion engine is substantially equal to the intake air sucked from the outside. According to this aspect, since it is possible to scavenge the bypass passage using the exhaust flow formed by this clean exhaust, it is possible to always maintain the moisture adsorption capacity of the adsorbent above a certain level. It becomes possible. Further, it is possible to prevent the condensed water adsorbed from being discharged at an undesirable timing due to the adsorbent exceeding saturation or the like. In view of the physical life of the adsorbent, it is desirable that the fluctuation range of the adsorption amount is not large. In this respect, this embodiment is advantageous.

  In another aspect of the exhaust gas purification system for an internal combustion engine according to the present invention, the vehicle is a hybrid vehicle including a rotating electrical machine as a power source.

  In this type of hybrid vehicle, EV (Electric Vehicle) traveling can be performed by the power of the rotating electrical machine, and the operating frequency of the internal combustion engine is lower than that of a vehicle having only the internal combustion engine as a power source. . For this reason, when the internal combustion engine is started, the possibility that condensed water is present in the exhaust gas is relatively high. In particular, in the case of a so-called PHV (Plug-in Hybrid Vehicle) in which power storage means such as a battery capable of inputting / outputting electric power to / from a rotating electric machine is configured to be appropriately chargeable by an external power source, further The trend can be significant. In view of such a point, the exhaust gas purification system for an internal combustion engine according to the present invention can be suitably applied to this type of hybrid vehicle.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

1 is a schematic block diagram conceptually showing a configuration of a hybrid vehicle according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view conceptually and schematically illustrating a one-plane configuration of an engine provided in the hybrid vehicle in FIG. 1. FIG. 3 is a schematic cross-sectional view conceptually showing a cross-sectional configuration of EHC along the extension direction of the exhaust pipe in the engine of FIG. 2. 3 is a flowchart of EHC leakage prevention control executed by an ECU. It is a flowchart of EHC leakage prevention control which concerns on 2nd Embodiment of this invention.

<Embodiment of the Invention>
Hereinafter, various embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
<Configuration of Embodiment>
First, the configuration of the hybrid vehicle 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram conceptually showing the configuration of the hybrid vehicle 10.

  In FIG. 1, a hybrid vehicle 10 includes a speed reduction mechanism 11, a drive wheel 12, an accelerator opening sensor 13, a vehicle speed sensor 14, an ECU 100, an engine 200, a motor generator MG1 (hereinafter abbreviated as “MG1” as appropriate), and a motor generator MG2. (Hereinafter abbreviated as “MG2” as appropriate), a hybrid vehicle as an example of a “vehicle” according to the present invention, including a power split mechanism 300, an EHC 400, a switching valve 500, a PCU 600, and a battery 700.

  The speed reduction mechanism 11 is a gear mechanism including a differential gear (not shown) and a planetary gear. The speed of the drive shaft (not shown), which is the power output shaft of the power split mechanism 300, is adjusted according to a predetermined reduction ratio. 12 is configured to be able to transmit to an axle connected to the vehicle. Note that the configuration of the speed reduction mechanism is not limited to that of the speed reduction mechanism 11, and various modes can be adopted. For example, the speed reduction mechanism may have a function as a speed change mechanism capable of realizing a plurality of shift speeds by a plurality of clutches and brakes and a planetary gear mechanism.

  The ECU 100 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like, and is configured to be able to control the entire operation of the hybrid vehicle 10. The “first control means”, “specification means”, and “ It is an example of “control means”. The ECU 100 is configured to be able to execute EHC leakage prevention control, which will be described later, according to a control program stored in the ROM.

  The ECU 100 is an integrated electronic control unit configured to function as an example of each of the “first control unit”, the “specification unit”, and the “second control unit” according to the present invention. All such operations are configured to be executed by the ECU 100. However, the physical, mechanical, and electrical configurations of each of the units according to the present invention are not limited to this. For example, each of these units includes a plurality of ECUs, various processing units, various controllers, a microcomputer device, and the like. It may be configured as various computer systems.

  The engine 200 is a gasoline engine as an example of the “internal combustion engine” according to the present invention that can function as a power source of the hybrid vehicle 10. Here, a detailed configuration of the engine 200 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view conceptually and schematically illustrating the one-plane configuration of the engine 200. In the figure, the same reference numerals are given to the same portions as those in FIG. 1, and the description thereof will be omitted as appropriate.

  The engine 200 is an in-line four-cylinder gasoline engine that is an example of an “internal combustion engine” according to the present invention that uses gasoline as fuel. The outline of the engine 200 will be described. The engine 200 has a configuration in which four cylinders 202 are arranged in parallel in a cylinder block 201. A force generated when an air-fuel mixture containing fuel is ignited by an ignition operation of an ignition device (not shown) in each cylinder causes a piston (not shown) to reciprocate in a direction perpendicular to the paper surface, and further via a connecting rod. The crankshaft (none of which is not shown) connected to the piston is converted into a rotational motion. Below, the principal part structure of the engine 200 is demonstrated with a part of the operation | movement.

  The engine 200 according to this embodiment is an in-line four-cylinder gasoline engine in which four cylinders 202 are arranged in parallel in a direction perpendicular to the paper surface in FIG. 1, but the configuration of the individual cylinders 202 is equal to each other. Here, only one cylinder 202 will be described. Further, the engine 200 in the present embodiment is a gasoline engine, but the “internal combustion engine” according to the present invention may be a diesel engine using light oil as fuel as a preferred form, or alcohol or alcohol mixed An engine using fuel as fuel may also be used.

  When the air-fuel mixture burns in the cylinder 202, the intake air, which is the air sucked from the outside through the air filter, is guided to the intake pipe 203. A throttle valve 204 capable of adjusting the amount of intake air is disposed in the intake pipe 203. The throttle valve 204 is a rotary valve that is configured to be rotatable by a driving force supplied from a throttle valve motor (not shown) that is electrically connected to the ECU 100 and controlled by the ECU 100 in a higher level. The rotation position is continuously controlled from the fully closed position where the upstream and downstream portions of the intake pipe 203 at the boundary are substantially blocked to the fully open position where the intake pipe 203 is communicated almost entirely.

  The intake pipe 203 communicates with the intake manifold 205, and further communicates with the intake port 206 formed in the cylinder block 201 corresponding to each cylinder via the intake manifold 205. On the other hand, the intake air guided to the intake pipe 203 is mixed with EGR gas, which will be described later, at the merging position on the upstream side of the intake manifold 205, and is configured to allow the intake port 206 and the inside of the cylinder to communicate with each other. When the intake valve is opened, it is sucked into the cylinder 202 as intake air.

  In the cylinder 202, gasoline as fuel is injected from a cylinder direct injection type unit injector 207, and the injected fuel is mixed with the intake air in each cylinder, and Become. Although details are omitted, the fuel is stored in a fuel tank (not shown), pumped out of the fuel tank by the action of a feed pump (not shown), and various known modes are provided via a low-pressure pipe (not shown). It is configured to be pumped to a high pressure pump (not shown). This high-pressure pump is configured to be able to supply fuel to the common rail 208.

  The common rail 208 is electrically connected to the ECU 100 and is configured to store high pressure fuel supplied from the upstream side (that is, the high pressure pump side) up to a target rail pressure set by the ECU 100. It is. The common rail 208 is provided with a rail pressure sensor capable of detecting the rail pressure and a pressure limiter for limiting the amount of fuel accumulated so that the rail pressure does not exceed the upper limit value. The illustration is omitted. The unit injector 207 described above is mounted for each cylinder 202, and each unit injector 207 is connected to the common rail 208 via the high-pressure delivery 209.

  The above-mentioned air-fuel mixture is ignited and burned by the ignition operation of the ignition device in the compression process, and is linked to the opening and closing of the intake valve as exhaust gas including burned gas or partially unburned HC and CO due to incomplete combustion. When an exhaust valve (not shown) that opens and closes is opened, the exhaust manifold 211 is guided through an exhaust port 210 formed in the cylinder block 201. The exhaust manifold 211 communicates with the exhaust pipe 212. The exhaust pipe 212 is an example of the “main exhaust passage” according to the present invention.

  In addition to the exhaust pipe 212, an EGR passage 213 communicates with the exhaust manifold 211. The EGR passage 213 is a metal and hollow tubular member that allows the exhaust manifold 211 and the intake pipe 203 to communicate with each other. The EGR passage 213 is configured to communicate with the intake pipe 203 at the above-described joining position, and is configured to be able to recirculate a part of the exhaust gas to the intake pipe 203 as EGR gas. An EGR cooler 214 is installed in the EGR passage 213. The EGR cooler 214 is a cooling device provided in the EGR passage 213. The EGR cooler 213 is a metallic and hollow tubular member having a cooling water pipe extending around the outer periphery of the engine 200, and is configured to cool the exhaust gas passing through the EGR cooler 214.

  The EGR valve 215 is a valve mechanism including an openable / closable valve body installed in the EGR passage 213 and a driving device that drives the valve body. The valve body of the EGR valve 215 is configured so that the open / close state is continuously changed by the driving device, and the flow rate of the EGR gas flowing through the EGR passage 213, that is, the EGR amount is controlled according to the open / close state. It is configured to be possible. The drive device of the EGR valve 215 is electrically connected to the ECU 100, and the opening / closing state of the valve body of the EGR valve 215 is controlled by the ECU 100 to the upper level.

  A three-way catalyst 216 is installed in the exhaust pipe 212. The three-way catalyst 216 carries a noble metal such as platinum on a basic carrier such as alumina and has a cross section along the radial direction of the exhaust pipe 212 having a honeycomb shape, and a reduction reaction of NOx (nitrogen oxide) in the exhaust. The exhaust emission control device is configured to be able to purify the exhaust gas by causing the oxidation reaction of CO (carbon monoxide) and HC (hydrocarbon) in the exhaust gas to proceed substantially simultaneously.

  The engine 200 includes an EHC 400 as an example of the “electrically heated catalyst device” according to the present invention on the upstream side of the three-way catalyst 216 in the exhaust pipe 212. The EHC 400 will be described later.

  Here, a part of the exhaust pipe 212 on the upstream side of the EHC 400 is a bypassed section that is bypassed by the bypass passage 217. The bypass passage 217 is provided with an adsorbent 218 that is configured to be able to adsorb moisture and is an example of the “adsorption means” according to the present invention.

  The merged portion of the bypass passage 217 and the exhaust pipe 212 on the downstream side of the adsorbent 218 (the “downstream side” is a directional concept based on the exhaust flow direction, that is, the EHC 400 side). Is provided with a switching valve 500. The switching valve 500 has three ports (i.e., a first port that communicates with the exhaust pipe 212 on the exhaust manifold 211 side, a second port that communicates with the bypass passage 217, and a third port that communicates with the exhaust pipe 212 on the EHC 400 side). , A communication port), a valve body 520 rotatably installed inside the case 510, and a drive system (not shown) for driving the valve body 520 according to the present invention. It is an example of a “switching valve”.

  In the switching valve 500, the valve body 520 closes the first port to bypass the bypassed section and bypasses the bypassed section, and bypasses the bypass port 217 by closing the second port and bypassing the second port. The rotation range is between the exhaust gas and the non-bypass position where the exhaust is led to the ECU 400, and the position of the valve body 520 is variably controlled within the rotation range. In addition, the valve body 520 may be configured such that the valve body position is controlled in a binary manner between the bypass position and the non-bypass position. Note that the drive system of the switching valve 500 (mainly the drive system that drives the motor) is electrically connected to the ECU 100, and the operation state of the switching valve 500 is controlled to the upper level by the ECU 100. .

  Here, the EHC 400 will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view conceptually showing a cross-sectional configuration of the EHC 400 along the extending direction of the exhaust pipe 212. In the figure, the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof will be omitted as appropriate.

  3, the EHC 400 includes a case 410, a heat insulating member 420, an EHC carrier 430, a temperature sensor 440, a positive electrode 450, a positive electrode coating portion 460, a negative electrode 470, and a negative electrode coating portion 480. This is an electrically heated catalyst device as an example of “EHC” according to the above.

  The case 410 is a housing of the EHC 400 made of a metal material, and is connected to the exhaust pipe 212 via a coupling member (not shown) at each of the upstream and downstream ends thereof.

  The heat insulating member 420 is installed so as to cover the inner peripheral surface of the case 410, and has heat insulation and electrical insulation.

  The EHC carrier 430 is a conductive catalyst carrier whose cross section perpendicular to FIG. 3 forms a honeycomb shape. The EHC carrier 430 carries an oxidation catalyst (not shown) so that the exhaust gas passing through the EHC 400 can be appropriately purified. The catalyst supported on the EHC carrier 430 may be a three-way catalyst. In this case, the distribution of the noble metal may be different from that of the three-way catalyst 216 on the downstream side. The engine 200 may have other catalyst devices such as an NSR (Nox Storage Reduction) catalyst in addition to or instead of the three-way catalyst 216.

  The positive electrode 450 is an electrode for applying a positive voltage whose one end is fixed in the vicinity of the end on the exhaust upstream side of the EHC carrier 430. The other end of the positive electrode 450 is connected to a PCU 600 described later. The positive electrode 450 is partially covered with a resin-made positive electrode coating 460 having electrical insulation, and the case 410 and the positive electrode 450 are maintained in an electrically insulated state.

  The upstream temperature sensor 440 is a sensor attached to a portion in the vicinity of the positive electrode 450 in the EHC carrier 430 and configured to detect the upstream EHC temperature as the temperature of the portion. The upstream temperature sensor 440 is electrically connected to the ECU 100, and the detected upstream EHC temperature is referred to by the ECU 100 at a constant or indefinite period.

  The negative electrode 470 is an electrode for supplying a reference potential whose one end is fixed near the end of the EHC carrier 430 on the exhaust downstream side. The other end of the negative electrode 470 is connected to the PCU 600 described later. The negative electrode 470 is partially covered with a resin-made negative electrode coating 480 having electrical insulation, and the case 410 and the negative electrode 470 are maintained in an electrically insulated state.

  The downstream temperature sensor 490 is a sensor attached to the vicinity of the negative electrode 470 in the EHC carrier 430 and configured to detect the downstream EHC temperature as the temperature of the part. The downstream temperature sensor 490 is electrically connected to the ECU 100, and the detected downstream EHC temperature is referred to by the ECU 100 at a constant or indefinite period.

  In the EHC 400 having such a configuration, when a drive voltage Vd, which is a positive applied voltage, is applied to the positive electrode 450 with reference to the potential of the negative electrode 470, a current flows through the conductive EHC carrier 430, and the EHC carrier 430 Generates heat. Due to this heat generation, the temperature rise of the oxidation catalyst carried on the EHC carrier 430 is promoted, and the EHC 400 is configured to promptly shift to the catalyst active state.

  Such a configuration of the EHC 400 is merely an example, and for example, the configuration of the EHC carrier, the attachment mode of each electrode, the control mode, and the like can take various known modes.

  Here, in the EHC 400, a conductive material having a relatively large electric resistance is used as the EHC carrier 430 for the purpose of sufficiently securing the heat capacity. In order to sufficiently generate heat in the EHC carrier 430 having a large heat mass, the EHC 400 generates a drive voltage Vd during normal driving for the purpose of warming up the catalyst by supplying power from the PCU 600 using the battery 700 described later as a power source. The voltage is set to a relatively high voltage of about 200V.

  Returning to FIG. 1, the motor generator MG1 is configured to function as a generator for charging the battery 700 or supplying power to the motor generator MG2, and further as an electric motor for assisting the power of the engine 200. The motor generator is an example of the “rotary electric machine” according to the present invention.

  Motor generator MG2 is a motor generator as another example of the “rotating electric machine” according to the present invention, which is configured to function as an electric motor for assisting the power of engine 200 or as a generator for charging battery 700. It is.

  The motor generator MG1 and the motor generator MG2 are configured as, for example, a synchronous motor generator, and include a rotor having a plurality of permanent magnets on the outer peripheral surface, and a stator wound with a three-phase coil that forms a rotating magnetic field. Prepare. However, other types of motor generators may be used.

  Power split device 300 is a planetary gear mechanism configured to be able to distribute engine torque Te, which is the output power of engine 200, to MG1 and the drive shaft. In addition, since the structure of the power split mechanism 300 can take various well-known aspects, a detailed description thereof is omitted here, but in brief, the power split mechanism 300 includes a sun gear provided at the center, A ring gear concentrically provided on the outer periphery of the sun gear, a plurality of pinion gears disposed between the sun gear and the ring gear and revolving while rotating on the outer periphery of the sun gear, and coupled to an end of the crankshaft 205, And a planetary carrier that supports the rotation shaft of each pinion gear.

  The sun gear is coupled to the rotor (not shown) of the MG 1 via the sun gear shaft, and the ring gear is coupled to the rotor (not shown) of the MG 2 via the drive shaft and the speed reduction mechanism 11. The drive shaft is connected to the axle as described above, and the motor torque supplied from the MG 2 is transmitted to the axle via the drive shaft and the speed reduction mechanism 11, and is similarly transmitted to the wheel 12 via the axle. Is input to the MG 2 via the speed reduction mechanism 11 and the drive shaft. Under such a configuration, the engine torque Te is transmitted to the sun gear and the ring gear by the power carrier mechanism 300 and the pinion gear, and the engine torque Te is divided into two systems.

  At this time, the MG1 can function as a reaction force element by controlling its output torque so as to balance the engine torque Te transmitted to the sun gear, for example. For this reason, according to power split device 300, it is possible to freely control the rotational speed of engine 200 by controlling the rotational speed of MG1. Using this characteristic, in the hybrid vehicle 10, MG1 is used as a rotation speed control device of the engine 200, the operating point of the engine 200 is maintained at, for example, the optimum fuel consumption operating point, and cranking at the time of starting the engine 200 is performed. Etc. are executed.

  Battery 700 is a rechargeable storage battery configured to be able to function as a power supply source related to power for powering motor generator MG1 and motor generator MG2.

  The PCU 600 converts the DC power extracted from the battery 700 into AC power, supplies the AC power to the motor generator MG1 and the motor generator MG2, and converts AC power generated by the motor generator MG1 and the motor generator MG2 into DC power. It includes an inverter (not shown) configured to be able to supply the battery 700, and input / output of power between the battery 700 and each motor generator, or input / output of power between the motor generators (that is, In this case, the electric power control unit is configured to be capable of controlling power transfer between the motor generators without using the battery 700. The PCU 600 is electrically connected to the ECU 100, and its operation is controlled by the ECU 100.

  On the other hand, the PCU 600 is electrically connected to the positive and negative electrodes of the EHC 400, and is configured to be able to supply the DC drive voltage Vd to the positive electrode 450. A drive current Id corresponding to the DC drive voltage Vd is generated in the EHC carrier 430, and the EHC carrier 430 generates heat in accordance with Joule heat generated by the drive current Id and the electric resistance R of the EHC carrier 430. Yes.

  On the other hand, the PCU 600 is also electrically connected to the switching valve 500, and can appropriately supply a driving voltage to a motor that is a driving source of the switching valve 500.

  The accelerator opening sensor 13 is a sensor that can detect an accelerator opening Ta that is an operation amount of an accelerator pedal (not shown) in the hybrid vehicle 10. The accelerator opening sensor 13 is electrically connected to the ECU 100, and the detected accelerator opening Ta is referred to by the ECU 100 at a constant or indefinite period. The vehicle speed sensor 14 is a sensor configured to be able to detect the vehicle speed V of the hybrid vehicle 10. The vehicle speed sensor 14 is electrically connected to the ECU 100, and the detected vehicle speed V is referred to by the ECU 100 at a constant or indefinite period.

<Operation of Embodiment>
The exhaust gas of the engine 200 contains moisture as a component. When the temperature of the exhaust pipe 212 is low, this moisture may be deprived of heat by the pipe wall of the exhaust pipe 212 and may be condensed in the exhaust pipe 212. Condensed water generated by this condensation adheres to the pipe wall of the exhaust pipe 212 and causes condensation in the exhaust pipe 212. On the other hand, the EHC 400 is installed in the exhaust pipe 212, and the condensed water generated on the upstream side of the EHC 400 is guided to the EHC 400 during the operation period of the engine 200.

  As described above, the EHC 400 is energized by applying the drive voltage Vd between the positive and negative electrodes. For example, the EHC 400 is covered so that the condensed water reaching the EHC 400 covers the positive electrode 450 and the case 410. In the case where water is exposed to water, the positive electrode 450 and the case 410 are in an electrically conductive state, and there is a possibility that leakage occurs.

  As described above, the normal driving voltage Vd of the EHC 400 is set to a high voltage of about 200 V in order to quickly raise the temperature of the EHC carrier 430 having a large heat mass. It needs to be avoided reliably. On the other hand, the EHC 400 plays a role in reducing emissions when the engine 200 is cold-started. In order to give priority to avoiding this type of leakage, avoiding deterioration of emissions if energization is continuously prohibited when an appropriate energization request is made. It becomes a difficult problem. That is, when an electrically heated catalyst device such as EHC400 is mounted on a vehicle including the hybrid vehicle 10, it is necessary to reliably avoid electric leakage without reducing the effectiveness of the electrically heated catalyst device.

  In the hybrid vehicle 10, such a problem is preferably solved by the EHC leakage prevention control executed by the ECU 100. Here, the details of the EHC leakage prevention control will be described with reference to FIG. FIG. 4 is a flowchart of EUC leakage prevention control.

  In FIG. 4, ECU 100 determines whether or not EHC 400 is in an energized state (step S101). The ECU 100 is configured to control the PCU 600 so that the EHC 400 is energized when the engine 200 is started. This energization of the EHC 400 causes the temperature of the EHC carrier 430 to reach the activation temperature of the supported oxidation catalyst. Alternatively, the configuration is continued until the temperature of the three-way catalyst 216 downstream of the EHC 400 reaches the catalyst activation temperature. The practical mode of energizing the EHC 400 is not limited to this, and various known control modes can be applied, for example.

  When the EHC 400 is not in an energized state (step S101: NO), the ECU 100 controls the valve body position of the switching valve 500 to a non-pipas position and closes the bypass passage 217 (step S104). On the other hand, when EHC 400 is in the energized state (step S101: YES), ECU 100 determines whether or not the temperature of EHC 400 is less than 100 ° C. (step S102). Here, as the temperature of the EHC 400, the lower one of the upstream EHC temperature and the downstream EHC temperature described above is employed. By adopting such a lower temperature, the influence of the temperature distribution in the EHC 400 can be eliminated as much as possible.

  If the temperature of EHC 400 is 100 ° C. or higher (step S102: NO), ECU 100 advances the process to step S104, and controls the valve body position of switching valve 500 to the non-bypass position as described above. On the other hand, when the temperature of the EHC 400 is less than 100 ° C. (step S102: YES), the ECU 100 controls the valve body position of the switching valve 500 to the bypass position and blocks the inflow of exhaust gas into the bypassed section of the exhaust pipe 212. (Step S103). When step S103 or step S104 is executed, the process returns to step S101, and a series of processes is repeated. The EHC leakage prevention control is executed as described above.

  Thus, according to the EHC leakage prevention control according to the present embodiment, when the EHC 400 is in the energized state, the temperature of the EHC 400 is 100 ° C. (that is, an example of the “reference value” according to the present invention. For a period less than (which may be a higher value), the exhaust gas is guided to the bypass passage 217 and the moisture in the exhaust gas is adsorbed by the adsorbent 218. As a result, exhaust that does not contain condensed water or exhaust with reduced amount of condensed water, or dry exhaust with reduced humidity flows into the ECH 400 if it is moist exhaust before the generation of condensed water.

Therefore, the possibility of electrical leakage occurring in the energized EHC 400 is significantly reduced, and ideally such possibility is eliminated. In other words, it is possible to reliably prevent the ECH 400 from leaking without reducing the effectiveness of the EHC 400 such as exhaust purification at the time of starting the engine.
<Second Embodiment>
Next, EHC leakage prevention control according to the second embodiment of the present invention will be described. FIG. 5 is a flowchart of the EHC leakage prevention control according to the second embodiment. In the figure, the same reference numerals are given to the same parts as those in FIG. 4, and the description thereof will be omitted as appropriate.

  In FIG. 5, if the EHC 400 is in a non-energized state (step S101: NO), or if the temperature of the EHC 400 is 100 ° C. or higher even when the EHC 400 is in an energized state (step S102: NO), the ECU 100 Is in a deceleration fuel cut state (step S201). The ECU 100 is configured to execute a deceleration fuel cut control that stops the fuel supply when the vehicle deceleration state continues for a certain period during the operation period of the engine 200 as a control different from the ECH leakage prevention control. ing.

  If engine 200 is not in the deceleration fuel cut state (step S201: NO), that is, if engine 200 is in normal operation, ECU 100 advances the process to step S104. On the other hand, when engine 200 is in the deceleration fuel cut state (step S201: YES), ECU 100 proceeds the process to step S103 and controls the valve body position of switching valve 500 to the bypass position.

  According to the EHC leakage prevention control according to the present embodiment, when the EHC 400 is in a non-energized state, or when the temperature of the EHC 400 is 100 ° C. or higher even in the energized state, that is, in terms of the original purpose, the exhaust gas is exhausted. When it is not necessary to adsorb the moisture in the adsorbent 218, the engine 200 is in a deceleration fuel cut state, that is, the exhaust is just intake air or dry air close thereto. The exhaust can be introduced into the bypass passage 217.

  When a dry gas similar to intake air is introduced into the bypass passage 217 in this way, the entire bypass passage 217 including the adsorbent 218 is scavenged by the dry air and supplied to the EHC 400 in a state containing a little moisture. . On the other hand, at this time, the EHC 400 is in a non-energized state or is in a state in which the evaporation of moisture is sufficiently accelerated even in the energized state. Is remarkably low. That is, without causing leakage in the EHC 400, the bypass passage 217 and the adsorbent 218 are scavenged, and the adsorption capacity of the adsorbent 218 having a finite adsorption limit can always be maintained in a suitable range. This makes it possible to prevent a situation in which the adsorbent 218 exceeds saturation and releases adsorbed moisture at an unexpected timing.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. The purification device is also included in the technical scope of the present invention.

  The exhaust gas purification system for an internal combustion engine according to the present invention can be used as an exhaust gas purification device for an internal combustion engine for a vehicle.

  DESCRIPTION OF SYMBOLS 10 ... Hybrid vehicle, 100 ... ECU, 200 ... Engine, 202 ... Cylinder, 203 ... Intake pipe, 211 ... Exhaust manifold, 212 ... Exhaust pipe, 217 ... Scavenging passage, 300 ... Power split mechanism, 400 ... EHC, 410 ... Case , 420 ... heat insulating member, 430 ... EHC carrier, 440 ... upstream temperature sensor, 450 ... positive electrode, 470 ... negative electrode, 490 ... downstream temperature sensor, 500 ... switching valve, 510 ... case, 520 ... valve body, 600 ... PCU, 700 ... battery.

Claims (4)

An exhaust purification system for an internal combustion engine mounted on a vehicle,
An electrically heated catalyst device installed in the main exhaust passage of the internal combustion engine and generating heat when energized;
A bypass passage provided to bypass a predetermined bypassed section in the main exhaust passage on the upstream side of the electrically heated catalyst device;
An adsorption means installed in the bypass passage and capable of collecting moisture in the exhaust;
A switching valve capable of opening and closing the bypass passage;
First control means for controlling the electric heating catalyst device so that the energization is performed when starting the internal combustion engine;
A specifying means for specifying the temperature of the electrically heated catalyst device;
An exhaust gas purification system for an internal combustion engine, comprising: second control means for controlling the switching valve so that the exhaust gas is led to the bypass passage when the specified temperature is lower than a reference value. The exhaust gas purification system for an internal combustion engine according to claim 1, wherein the reference value is a temperature of 100 ° C or higher. The exhaust of the internal combustion engine according to claim 1 or 2, wherein the second control means controls the switching valve so that the exhaust is guided to the bypass passage during a deceleration fuel cut period of the internal combustion engine. Purification system. The exhaust purification system for an internal combustion engine according to any one of claims 1 to 3, wherein the vehicle is a hybrid vehicle including a rotating electric machine as a power source.

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