JP2009019604A - Exhaust purification device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance purification performance of purifying exhaust gas produced in an internal combustion engine. <P>SOLUTION: An exhaust purification device is configured to include: a main passage 11m into which exhaust gas produced after engine combustion is introduced; a main catalyst 13m disposed in the main passage 11m for purifying the exhaust gas introduced into the main passage 11m; a bypass passage 11b into which the exhaust gas is introduced bypassing the main passage 11m upstream of the main catalyst 13m; a bypass catalyst 13b disposed in the bypass passage 11b for purifying the exhaust gas introduced into the bypass passage 11b; a main changeover valve 12m and a bypass changeover valve 12b for selectively change over a passage into which the exhaust gas is introduced between the main passage 11m and the bypass passage 11b; and a control unit 22 for performing a changeover operation between the main changeover valve 12m and the bypass changeover valve 12b as soon as an engine starts, selecting the bypass passage 11b, and introducing the exhaust gas into the selected bypass passage 11b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that purifies exhaust gas generated by combustion of the internal combustion engine, and more particularly to an exhaust gas purification apparatus for an internal combustion engine with improved switching control between a main passage and a bypass passage through which the exhaust gas flows.

  In a conventional internal combustion engine exhaust gas purification device, a catalyst for purifying exhaust gas exhausted after combustion of the engine is provided in the exhaust passage, and by the action of this catalyst, nitrogen carbide (HC) contained in the exhaust gas, monoxide Toxic substances such as carbon (CO) and nitrogen oxides (NOx) are purified.

  Since such a catalyst is generally activated at a high temperature, the activation temperature of the catalyst was not reached at a relatively low temperature of the exhaust gas immediately after starting the internal combustion engine. For this reason, the catalyst is not sufficiently activated for the exhaust gas immediately after the internal combustion engine is started, and it is difficult to sufficiently purify the exhaust gas.

  Therefore, a technique has been proposed that employs two types of catalysts having different activation temperatures, a catalyst having a high activation temperature and a catalyst having a lower activation temperature. In this technique, a bypass passage in which a bypass catalyst having a relatively low activation temperature and a high purification effect is arranged in parallel with the main passage with respect to the main passage upstream of the main catalyst having a relatively high activation temperature. The exhaust gas is selectively guided to the bypass passage by the switching valve according to the temperature of the exhaust gas. By adopting such technology, the exhaust gas is guided by the bypass catalyst until the exhaust temperature of the exhaust gas reaches the activation temperature of the main catalyst arranged in the main passage. It becomes possible to sufficiently purify.

As conventional techniques for purifying the exhaust gas by changing the exhaust gas passage in this way, for example, those described in the following documents are known (see Patent Documents 1 and 2). Document 1 proposes a technology that changes the exhaust gas exhaust passages during low / medium-load operation and high-load operation of the engine and purifies the exhaust gas via a three-way catalyst provided in each exhaust passage. Has been. Further, in Document 2, an exhaust passage is formed by a main passage in which a main catalytic converter is disposed and a bypass passage in which a bypass catalytic converter is disposed, and the exhaust gas guided to the bypass passage immediately after the cold start is bypass catalyst. A technique is described in which, after being purified by the converter and the main catalytic converter is sufficiently activated, the exhaust gas is mainly guided to the main passage and purified by the main bypass catalytic converter.
JP 2005-320894 A JP 2006-299937 A

  In the apparatus for purifying exhaust gas by using two kinds of catalysts having different activation temperatures by switching the exhaust gas exhaust passage by the switching valve described above, the switching valve for switching the exhaust passage operates the ignition switch (ON). Based on the above, switching control is performed by the control device. In most recent electronic vehicles, this control device is composed of an in-vehicle microcomputer. For this reason, at the same time as the ignition switch is turned on, the control device is energized from the vehicle-mounted battery and starts to start.

  The microcomputer that constitutes the control device is in accordance with the specifications of the microcomputer until the start is started, the predetermined initialization operation is completed, and the output is stabilized to the extent that the switching valve can be switched and controlled as instructed. A predetermined time set is required. For this reason, immediately after the ignition switch is turned on and the engine is started, there is a possibility that the initialization of the control device is not in time and the switching valve cannot be switched accurately. In such a case, the exhaust gas discharged immediately after the engine is started is not reliably guided to the bypass passage, and there is a possibility that the exhaust gas is exhausted without being purified by the low temperature catalyst.

  Accordingly, the present invention has been made in view of the above, and an object of the present invention is to provide an exhaust gas purification apparatus for an internal combustion engine with an increased purification capability of exhaust gas generated in the internal combustion engine.

  In order to achieve the above object, an invention according to claim 1 is directed to a main passage through which exhaust gas generated after combustion of an internal combustion engine is guided, and an exhaust gas disposed in the main passage and guided through the main passage. A first catalyst for purifying gas; a bypass passage for guiding exhaust gas by bypassing the main passage on the upstream side of the first catalyst; and a bypass passage disposed in the bypass passage for guiding the bypass passage A second catalyst for purifying the exhaust gas, a switching means for selectively switching a passage through which the exhaust gas is guided to the main passage or the bypass passage, and at the same time when the internal combustion engine is started, by the switching means. And a control means for starting the switching operation, selecting the bypass passage, and guiding the exhaust gas to the selected bypass passage.

  According to the first aspect of the present invention, the exhaust gas passage can be quickly set as the bypass passage after the internal combustion engine is started. Thereby, the ratio of the exhaust gas immediately after the start of the internal combustion engine to be purified by the second catalyst can be increased as compared with the conventional case, and the exhaust gas purification processing capacity can be improved.

  According to a second aspect of the present invention, there is provided a main passage through which exhaust gas generated after combustion of an internal combustion engine is guided, and a first passage disposed in the main passage for purifying the exhaust gas guided through the main passage. A catalyst, a bypass passage that guides exhaust gas by bypassing the main passage upstream of the first catalyst, and an exhaust gas that is disposed in the bypass passage and guided through the bypass passage. A second catalyst, switching means for selectively switching a passage through which exhaust gas is guided to the main passage or the bypass passage, and detection for detecting a pre-starting operation performed in the vehicle before the internal combustion engine is started And when the pre-starting operation is detected by the detecting means and prior to starting the internal combustion engine, the non-energized state is shifted to the energized state. Control means for starting the switching operation by the switching means simultaneously with the start of the internal combustion engine, selecting the bypass passage, and guiding the exhaust gas to the selected bypass passage. It is characterized by having.

  According to the second aspect of the present invention, the exhaust gas passage can be quickly set as the bypass passage after the internal combustion engine is started. As a result, the ratio of the exhaust gas immediately after the start of the internal combustion engine to be purified by the second catalyst can be increased as compared with the conventional one, and the exhaust gas purification processing capacity can be improved. It is possible to achieve lower power consumption than in the case of the state.

  According to a third aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the first aspect, the control means is a cutoff that selectively stops energization with respect to a component that does not operate during the switching operation of the switching means. And the control means is such that when the internal combustion engine is constantly in an energized state and the internal combustion engine is not operating, the shut-off means stops the energization with respect to a component that does not operate during the switching operation of the switching means. Features.

  According to the third aspect of the present invention, even when the control means is always energized, it is possible to reduce power consumption.

  According to a fourth aspect of the present invention, there is provided a main passage through which exhaust gas generated after combustion of the internal combustion engine is guided, and a first passage disposed in the main passage for purifying the exhaust gas guided through the main passage. A catalyst, a bypass passage that guides exhaust gas by bypassing the main passage upstream of the first catalyst, and an exhaust gas that is disposed in the bypass passage and guided through the bypass passage. A switching means for selectively switching the passage through which exhaust gas is guided to the main passage or the bypass passage; and prior to starting the internal combustion engine when the start of the internal combustion engine is commanded. And a control means for starting the internal combustion engine after the switching operation by the switching means is completed and the bypass passage is selected to guide the exhaust gas and determine the passage as the bypass passage. And features.

  According to the fourth aspect of the invention, the exhaust gas immediately after starting the internal combustion engine can be reliably purified by the second catalyst, and the exhaust gas purification processing ability can be improved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an exhaust emission control device for an internal combustion engine according to Embodiment 1 of the present invention. In the apparatus of Embodiment 1 shown in FIG. 1, a main switching valve 12m is provided in a main passage 11m that constitutes an exhaust passage through which exhaust gas discharged after combustion of the engine is guided, and is downstream of the main switching valve 12m. The main catalyst 13m is arranged in the.

  The main switching valve 12m is a valve that controls opening and closing of the main passage 11m, and is controlled to open and close by a control device shown in FIG. The main catalyst 13m is composed of a high-temperature active catalyst that is activated at a relatively high temperature, and is sufficiently activated by exhaust gas that has reached an exhaust gas temperature range (for example, about 600 ° C. to 900 ° C.) during normal driving of the vehicle. The catalyst is made up of.

  The main passage 11m provided with the main switching valve 12m is provided with a bypass passage 11b in parallel with the main passage 11m. The bypass passage 11b is connected to the main passage 11m upstream of the main switching valve 12m and the main switching valve 12m. The main passage 11m is bypassed by connecting the main passage 11m downstream and upstream of the main catalyst 13m.

  A bypass switching valve 12b is provided in the bypass passage 11b, and a bypass catalyst 13b is disposed downstream of the bypass switching valve 12b.

  The bypass switching valve 12b is a valve that controls opening and closing of the bypass passage 11b, and is controlled to be opened and closed by a control device shown in FIG. The main switching valve 12m and the bypass switching valve 12b function as switching means for switching the passage through which the exhaust gas is guided.

  The switching means can also be configured by a three-way valve provided at a branch point between the main passage 11m and the bypass passage 11b.

  The bypass catalyst 13b is composed of a low-temperature activated catalyst that is activated at a relatively low temperature, and is composed of, for example, a noble metal catalyst that has a high purification effect against a low exhaust gas temperature immediately after the engine is started.

  FIG. 2 is a diagram showing a configuration of a control device that functions as control means for controlling the opening and closing of the main switching valve 12m and the bypass switching valve 12b. In FIG. 2, the control device includes a main switching valve opening / closing mechanism 21m that opens and closes the main switching valve 12m, a bypass switching valve opening / closing mechanism 21b that opens / closes the bypass switching valve 12b, and a control unit 22.

  The main switching valve opening / closing mechanism 21m has an opening / closing driving function by an actuator such as a motor, and opens / closes the main switching valve 12m. The bypass switching valve opening / closing mechanism 21b has an opening / closing driving function by an actuator such as a motor, and the bypass switching valve 12b is opened and closed.

  The control unit 22 functions as a control center that controls opening and closing of the main switching valve 12m and the bypass switching valve 12b to switch the exhaust gas flow path, and is necessary for a computer that controls various operation processes based on a program. , A microcomputer including a CPU, a storage device, an input / output device, and the like.

  The control unit 22 is always energized from the battery 23 of the vehicle on which the purification device for the internal combustion engine is mounted, the initialization is completed, and the output is stable. The control unit 22 recognizes the start of the engine and starts switching control of the main switching valve 12m and the bypass switching valve 12b based on, for example, an input of an ignition switch signal. The ignition switch signal is given from the ignition switch 24 to the control unit 22.

  Next, the switching control operation of the main switching valve 12m and the bypass switching valve 12b will be described with reference to the flowchart shown in FIG. 3 and the timing chart shown in FIG.

  First, as shown in FIG. 4, the microcomputer is always turned on and the microcomputer is in a stable output state. In such a state, when the ignition switch 24 is turned on and the engine is started (step S301). The ignition switch signal changes from the low level to the high level and is input to the control unit 22. The control unit 22 recognizes the start of the engine, immediately gives a main switching valve opening / closing signal for instructing the main switching valve 12m to close without performing an initialization operation, and supplies the bypass switching valve 12b to the main switching valve opening / closing mechanism 21m. A bypass switching valve opening / closing signal for commanding opening of the valve is given to the bypass switching valve opening / closing mechanism 21b. As a result, the main switching valve 12m shifts from the open state after the switching valve opening / closing response delay time to the closed state, and the bypass switching valve 12b changes from the closed state to the open state after the similar opening / closing response delay time. Transition is made (step S302).

  When the main switching valve 12m is closed and the bypass switching valve 12b is opened, the exhaust gas guided through the main passage 11m is branched and guided from the main passage 11m to the bypass passage 11b (step S303) and disposed in the bypass passage 11b. The exhaust gas having a relatively low temperature immediately after engine start is purified by the bypass catalyst 13b (step S304). Thereafter, a main switching valve opening / closing signal for instructing opening of the main switching valve 12m is given to the main switching valve opening / closing mechanism 21m, and a bypass switching valve opening / closing signal for closing the bypass switching valve 12b is supplied to the bypass switching valve opening / closing mechanism 21b. If given, the main switching valve 12m shifts from the closed state to the opened state after the switching valve opening / closing response delay time, and the bypass switching valve 12b shifts from the opened state to the closed state after the similar opening / closing response delay time. (Step S305).

  On the other hand, in the prior art in which the microcomputer is energized after the ignition switch is turned on, and then the initialization operation is performed in the microcomputer and the output is stabilized, the ignition switch is turned on as shown in the timing chart of FIG. After the ignition switch signal changes from low level to high level and engine start is recognized, the output is not stable until initialization is started and completed in the microcomputer. The control signal cannot be output.

  However, in the first embodiment, since the microcomputer is always energized from the battery 23 of the vehicle, the microcomputer is always in an output stable state, so that the main switching valve 12m and the bypass switch are immediately switched from the control unit 22 immediately after the engine is started. Since an opening / closing signal for opening and closing the valve 12b can be output, the main switching valve 12m and the bypass switching valve 12b can be switched and controlled quickly after the engine is started. As a result, the exhaust gas in a relatively low temperature state after the engine is started can be guided to the bypass passage 11b, and the purification process by the bypass catalyst 13b provided for the low temperature can be started earlier than before. As a result, it is possible to increase the proportion of exhaust gas immediately after engine startup that is purified by the low-temperature bypass catalyst 13b as compared with the prior art, and improve the exhaust gas purification capacity.

  FIG. 6 is a view showing a configuration of an exhaust gas purification apparatus for an internal combustion engine according to Embodiment 2 of the present invention. The feature of the second embodiment shown in FIG. 6 is that, compared to the configuration of the first embodiment, the pre-start operation performed in the vehicle by the driver or the like prior to the start of the engine is detected to detect the engine. A sensor 51 functioning as a detecting means for predicting and estimating the start is provided, and a control unit 53 including an internal power switch 52 is provided instead of the control unit 22 of the first embodiment. is there.

  The sensor 51 is a sensor that detects a pre-starting operation that predicts that the engine will be started before the ignition switch is turned on, and detects, for example, a pre-starting operation in which the door lock of the vehicle is released. It is composed of a door lock release sensor, a sensor that detects a pre-starting action when the vehicle door is opened, or a seating sensor that detects a pre-starting action when a driver is seated on the driver's seat. There is no particular limitation as long as it detects the operation before the engine is started by the driver. When it is detected that the door lock is released by these sensors 51, or when the door is opened, Alternatively, when it is detected that the driver is seated in the driver's seat, a sensor signal is input from the sensor 51 to the control unit 53.

  An internal power switch 52 provided in the control unit 53 controls energization from the battery 23 to the control unit 53 based on a sensor signal given from the sensor 51.

  Next, the switching control operation of the main switching valve 12m and the bypass switching valve 12b will be described with reference to the flowchart shown in FIG. 7 and the timing chart shown in FIG.

  First, when the pre-start operation is detected by the sensor 51 and it is estimated that the engine will be started (step S701), the sensor signal is changed from the low level to the high level as shown in the timing chart of FIG. It changes and is given to the internal power switch 52 of the control unit 53. As a result, the internal power switch 52 changes from the OFF state to the ON state, the battery 23 and the control unit 53 change from the electrically non-connected state to the connected state, and the control unit 53 shifts from the non-energized state to the energized state (step S702). ).

  When energization of the control unit 53 is started, the control unit 53 is activated and an initialization operation is started (step S703). After the initialization operation is completed and the output is stabilized, the ignition switch 24 is turned on and the engine is turned on. Is started (step S704), operations similar to those shown in steps S302 to S305 of FIG. 3 are performed, and both switching valves are immediately switched and controlled as in the first embodiment.

  In the second embodiment, when starting the control unit 53 prior to starting the engine, as compared with the first embodiment in which the control unit 22 is always energized as in the first embodiment, Since the control unit 53 is energized and activated by the internal power switch 52 when the engine start is predicted and estimated, in addition to the same effects as those of the first embodiment, in addition to the first embodiment. Compared to the above, low power consumption can be achieved.

  FIG. 9 is a diagram showing a configuration of an exhaust gas purification apparatus for an internal combustion engine according to Embodiment 3 of the present invention. The feature of the third embodiment shown in FIG. 9 is that the configuration in the control unit 71 is not related to the switching control of the switching valve immediately after the engine is started before the engine is started, as compared with the configuration of the first embodiment. The requirement is that the non-energized state is set, while the configuration requirement related to the switching control of the switching valve is that the energized state, and the rest is the same as in the first embodiment.

  In FIG. 9, a cutoff circuit 72 is provided in the control unit 71, and the cutoff circuit 72 controls energization / non-energization of a configuration not related to the switching control of the switching valve immediately after the engine is started.

  Next, the switching control operation of the main switching valve 12m and the bypass switching valve 12b will be described with reference to the flowchart shown in FIG.

  First, it is determined whether or not the engine is operating (step S1001). If the engine is not operating, the in-vehicle LAN is connected to the control unit (C / U) that controls the engine when the engine is operating. The communication is not performed (does not operate) immediately after the engine is started (ie, does not operate). For example, the communication circuit 73 is deenergized to turn off (step S1002). That is, when the engine is not operating, the microcomputer 74 sets the shut-off circuit 72 in a shut-off state based on the ignition switch signal. Thus, the communication circuit 73 is energized from the battery 23 via the power supply terminal 75 of the control unit 71 connected to the battery 23 and the power supply circuit 76 for adjusting the voltage of the battery 23 and the power supply voltage of the microcomputer 74 and the communication circuit 73. Blocked.

  After that, when the engine is started (step S1003) and an ignition switch signal is given to the microcomputer 74, the microcomputer 74 changes the cutoff circuit 72 from the cutoff state to the conductive state, and the communication circuit 73 is energized (step S1004). The same operation as that shown in steps S302 to S305 in FIG. 3 is performed, and both switching valves are immediately switched and controlled as in the first embodiment.

  In the third embodiment, when the engine is not operating, the switching is performed before starting the engine, compared to the first embodiment in which all the components in the control unit 22 are energized. Since a configuration in which a part of the control unit 71 that does not operate during valve switching control is not energized is adopted, the same effect as in the first embodiment can be obtained. Compared to 1, power consumption can be reduced.

  FIG. 11 is a diagram showing a configuration of an exhaust gas purification apparatus for an internal combustion engine according to Embodiment 4 of the present invention. The feature of the fourth embodiment shown in FIG. 11 is that the control unit 81 is selectively energized from the battery 23 via the ignition switch 24 and is given by the control unit 81 as compared with the configuration of the first embodiment. The engine starter means 82 for starting the engine based on the start activation permission signal is provided, and the other configuration is the same as that of the first embodiment.

  Next, the switching control operation of the main switching valve 12m and the bypass switching valve 12b will be described with reference to the flowchart shown in FIG. 12 and the timing chart shown in FIG.

  First, it is determined whether or not the ignition switch 24 is turned on by the control unit 81 (step S1201). When the ignition switch 24 is turned on, the control unit 81 is connected to the battery 23 and energized (step S1202). When the control unit 81 is energized, as shown in the timing chart of FIG. 9, initialization of the control unit 81 is started (step S1203), and when the initialization is completed, the output becomes stable.

  On the other hand, when the ignition switch 24 is turned on, the ignition switch signal changes from the low level to the high level and is given to the control unit 81. When the initialization of the control unit 81 is completed and the output is stabilized, the main switching valve 12m is closed. A main switching valve opening / closing signal is given from the control unit 81 to the main switching valve opening / closing mechanism 21m, and a bypass switching valve opening / closing signal for instructing opening of the bypass switching valve 12b is given from the control unit 81 to the bypass switching valve opening / closing mechanism 21b. The main switching valve 12m shifts from the valve opening state to the valve closing state after the switching valve opening / closing response delay time, and the bypass switching valve 12b shifts from the valve closing state to the valve opening state after the similar opening / closing response delay time ( Step S1204).

  Thereafter, the control unit 81 causes the engine starter means 82 after the switch valve opening / closing response delay time obtained in advance through experiments or the like has elapsed to close the main switch valve 12m and the bypass switch valve 12b. A starter activation permission signal is given (step S1205). As a result, the engine starter means 82 is activated to start the engine (step S1206), and thereafter, operations similar to those shown in steps S303 to S305 of FIG. 3 are performed.

  As described above, in the fourth embodiment, after the main switching valve 12m and the bypass switching valve 12b are reliably switched and controlled, the engine is started so that the exhaust gas is reliably guided to the bypass passage 11b and the bypass catalyst 13b. Can be purified. Therefore, in addition to being able to reliably purify the relatively low temperature exhaust gas immediately after the engine is started, the control unit 81 is not energized when the engine is not operating. Power consumption can be reduced.

1 is a diagram illustrating a configuration of an exhaust gas purification apparatus for an internal combustion engine according to a first embodiment of the present invention. It is a figure which shows the structure of the control system in the exhaust gas purification apparatus of the internal combustion engine which concerns on Example 1 of this invention. It is a flowchart which shows the procedure of the control action which concerns on Example 1 of this invention. It is a timing chart which shows the change of each signal concerning Example 1 of the present invention. It is a timing chart which shows change of each signal at the time of adopting conventional technology. It is a figure which shows the structure of the control system in the exhaust gas purification apparatus of the internal combustion engine which concerns on Example 2 of this invention. It is a flowchart which shows the procedure of the control action which concerns on Example 2 of this invention. It is a timing chart which shows the change of each signal concerning Example 2 of the present invention. It is a figure which shows the structure of the control system in the exhaust gas purification apparatus of the internal combustion engine which concerns on Example 3 of this invention. It is a flowchart which shows the procedure of the control action which concerns on Example 3 of this invention. It is a figure which shows the structure of the control system in the exhaust gas purification apparatus of the internal combustion engine which concerns on Example 4 of this invention. It is a flowchart which shows the procedure of the control action which concerns on Example 4 of this invention. It is a timing chart which shows the change of each signal concerning Example 4 of the present invention.

Explanation of symbols

11b ... Bypass passage 11m ... Main passage 12b ... Bypass switching valve 12m ... Main switching valve 13b ... Bypass catalyst 13m ... Main catalyst 21b ... Bypass switching valve opening / closing mechanism 21m ... Main switching valve opening / closing mechanism 22, 53, 71, 81 ... Control unit DESCRIPTION OF SYMBOLS 23 ... Battery 24 ... Ignition switch 51 ... Sensor 52 ... Internal power switch 72 ... Shut-off circuit 73 ... Communication circuit 74 ... Microcomputer 75 ... Power supply terminal 76 ... Power supply circuit 82 ... Engine starter means

Claims (4)

A main passage through which exhaust gas generated after combustion of the internal combustion engine is guided;
A first catalyst disposed in the main passage to purify exhaust gas guided through the main passage;
A bypass passage through which exhaust gas is guided around the main passage on the upstream side of the first catalyst;
A second catalyst disposed in the bypass passage and purifying the exhaust gas guided through the bypass passage;
Switching means for selectively switching a passage through which exhaust gas is guided to the main passage or the bypass passage;
Control means for starting the switching operation by the switching means simultaneously with the start of the internal combustion engine, selecting the bypass passage, and guiding the exhaust gas to the selected bypass passage. Exhaust purification device. A main passage through which exhaust gas generated after combustion of the internal combustion engine is guided;
A first catalyst disposed in the main passage to purify exhaust gas guided through the main passage;
A bypass passage through which exhaust gas is guided around the main passage on the upstream side of the first catalyst;
A second catalyst disposed in the bypass passage for purifying exhaust gas guided through the bypass passage;
Switching means for selectively switching a passage through which exhaust gas is guided to the main passage or the bypass passage;
Detecting means for detecting a pre-starting operation performed in the vehicle until the internal combustion engine is started;
When the pre-start operation is detected by the detection means, the non-energized state is shifted to the energized state prior to starting the internal combustion engine, and the switching operation by the switching means can be started simultaneously with the start of the internal combustion engine. And a control means for starting the switching operation by the switching means at the same time as starting the internal combustion engine at the same time, selecting the bypass passage, and guiding the exhaust gas to the selected bypass passage. An exhaust gas purification apparatus for an internal combustion engine characterized by the above. The control means includes a cutoff means for selectively stopping energization with respect to a component that does not operate during the switching operation of the switching means,
The control means is characterized in that, when the internal combustion engine is not operating at all times, the control means stops energization with respect to a component that does not operate during the switching operation of the switching means by the shut-off means. Item 6. An exhaust emission control device for an internal combustion engine according to Item 1. A main passage through which exhaust gas generated after combustion of the internal combustion engine is guided;
A first catalyst disposed in the main passage to purify exhaust gas guided through the main passage;
A bypass passage through which exhaust gas is guided around the main passage on the upstream side of the first catalyst;
A second catalyst disposed in the bypass passage for purifying exhaust gas guided through the bypass passage;
Switching means for selectively switching a passage through which exhaust gas is guided to the main passage or the bypass passage;
When the start of the internal combustion engine is commanded, prior to the start of the internal combustion engine, the switching operation by the switching means is completed, the bypass passage is selected, exhaust gas is guided, and the passage is changed to the bypass passage. An exhaust purification device for an internal combustion engine, comprising: control means for starting the internal combustion engine after being determined.

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