JP4461423B2 - Control method of exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to a method for controlling an exhaust gas purification apparatus for an internal combustion engine, and more particularly, to a method for controlling an exhaust gas purification apparatus for an internal combustion engine having a combustion burner for warming up a catalyst.

  In recent years, internal combustion engines mounted on automobiles and the like have been required to reduce harmful gas components in the exhaust for reasons such as environmental protection. As countermeasures, exhaust purification apparatuses that provide a catalyst or the like in the exhaust passage of an internal combustion engine to purify harmful components in the exhaust are generally studied and used.

  In particular, in the case of a diesel engine, it is an urgent task to reduce particulate matter (PM) and nitrogen oxides (NOx) contained in exhaust gas. In response to such demands, an internal combustion engine including a DPF (Diesel Particulate Filter), which is a kind of filter for capturing PM in exhaust gas, or a NOx reduction catalyst for reducing NOx, alone or in combination in an exhaust system. R & D is underway.

  By the way, for example, the DPF has a problem that it cannot be used continuously unless the collected PM is oxidized and removed. Therefore, as a technique for solving this problem, there is a technique called a continuous regeneration type DPF (DPR: Diesel Particulate active Reduction system) in which regeneration is performed continuously while running by using a catalyst. In this method, a catalyst is supported on the exhaust passage surface in the DPF to cause an oxidation reaction, and the trapped PM is combusted by the reaction heat at that time.

  The NOx reduction catalyst also needs to release and reduce and purify NOx when the NOx absorption efficiency is lowered. For this purpose, it is required to lower the atmospheric oxygen concentration or raise the temperature. It has been.

  On the other hand, diesel engines generally have a low exhaust temperature, which is a major obstacle for the DPR and the NOx reduction catalyst that require a catalyst temperature (hereinafter referred to as catalyst temperature) to be raised above a certain level. Therefore, various techniques for increasing the catalyst temperature in such a case have been proposed.

  For example, Patent Document 1 uses a technique for reaching an activation temperature in a short time by heating a catalyst of an exhaust purification device using a burner when the catalyst temperature is low at the time of starting an internal combustion engine, that is, using a burner. Thus, a technique for heating the catalyst is disclosed.

  For example, Patent Document 2 discloses a technique for increasing the temperature of a catalyst by adding fuel to an exhaust system. Specifically, a filter for collecting particulates disposed in the exhaust system of a diesel engine, a light oil supply means for supplying light oil to an oxidation catalyst disposed on the upstream side of the filter of the exhaust system, and a filter regeneration A heating means such as a burner that heats and vaporizes the light oil supplied from the light oil supply means to the oxidation catalyst when the temperature of the oxidation catalyst is lower than a predetermined value, and burns the light oil in the oxidation catalyst. A technique is disclosed that enables the regeneration of the filter in a specific region in the normal operation region by the combustion heat.

JP-A-5-86845 Japanese Patent Laid-Open No. 8-312331

  However, when the exhaust system is equipped with a combustion burner to raise the temperature of the catalyst, if the catalyst is heated using only the combustion heat of the combustion burner, the inlet temperature of the catalyst becomes higher than the outlet temperature. Therefore, in order to raise the outlet temperature to a sufficient temperature, it is necessary to raise the inlet temperature. However, since the catalyst has a heat-resistant temperature such as 700 ° C., the catalyst can be heated beyond the heat-resistant temperature. Can not. That is, as in the technique disclosed in Patent Document 1, only by heating the catalyst with a combustion burner, the inlet temperature cannot be sufficiently increased even if the inlet temperature can be sufficiently increased. There is a problem that the whole cannot be maintained at a predetermined temperature.

  In addition, as in the technique disclosed in Patent Document 2 described above, when light oil is heated and supplied to the oxidation catalyst to cause combustion of the light oil in the oxidation catalyst, the vicinity of the inlet at the inlet of the catalyst is the heat of combustion. In contrast to being heated by only the catalyst, the outlet of the catalyst is heated by the combustion heat from the inlet to the vicinity of the outlet in addition to the combustion heat in the vicinity of the outlet. Accordingly, in this case as well, there is a problem that the entire catalyst cannot be maintained at a predetermined temperature.

  Therefore, the present invention eliminates the above-described problems, and increases the catalyst outlet temperature while maintaining the catalyst inlet temperature within the heat resistant temperature of the catalyst, thereby maintaining the entire catalyst at a predetermined temperature without any temperature difference. It is an object of the present invention to provide a control method for an exhaust gas purification device for an internal combustion engine that enables the control.

  In order to solve the above-described problems, one aspect of the present invention is a control method for an exhaust gas purification apparatus for an internal combustion engine, in which an exhaust gas purification catalyst provided in an exhaust passage of the internal combustion engine is heated and controlled using a combustion burner. When the catalyst inlet temperature is lower than the first predetermined temperature or the catalyst outlet temperature is higher than the second predetermined temperature lower than the first predetermined temperature, the fuel burner is supplied with fuel and air. Combusting, and when the catalyst inlet temperature is equal to or higher than the first predetermined temperature and the catalyst outlet temperature is equal to or lower than the second predetermined temperature, at least the fuel is discharged without burning the combustion burner. It is characterized by controlling.

  According to another aspect of the present invention, there is provided a control method for an exhaust gas purification apparatus for an internal combustion engine in which an exhaust gas purification catalyst provided in an exhaust passage of the internal combustion engine is heated and controlled using a combustion burner. Is lower than the predetermined temperature or the difference between the inlet and outlet temperatures of the catalyst is smaller than the predetermined temperature difference, the combustion burner is supplied with fuel and air to burn, and the catalyst When the inlet temperature is equal to or higher than the predetermined temperature and the inlet / outlet temperature difference of the catalyst is equal to or higher than the predetermined temperature difference, the combustion burner is controlled to discharge at least fuel without burning.

  According to still another aspect of the present invention, there is provided a control method for an exhaust gas purification apparatus for an internal combustion engine in which an exhaust gas purification catalyst provided in an exhaust passage of the internal combustion engine is heated and controlled using a combustion burner. When the temperature is lower than the predetermined temperature, the combustion burner is burned by supplying fuel and air. When the inlet temperature is equal to or higher than the predetermined temperature and the combustion burner is already burned, the combustion time is predetermined. The combustion burner is controlled to discharge at least the fuel without burning when the time has passed.

  According to one aspect of the present invention, when the catalyst needs to be heated and the catalyst inlet temperature is lower than the first predetermined temperature or the outlet temperature is higher than the second predetermined temperature. The combustion type burner is burned and the catalyst is heated to a temperature higher than a predetermined temperature by the combustion heat supplied from the combustion type burner, and the inlet temperature of the catalyst is higher than the first predetermined temperature and the outlet temperature is the second temperature. When the temperature is lower than the predetermined temperature, unburned fuel is supplied to the catalyst from the combustion burner to cause spontaneous combustion on the catalyst so that the temperature of the catalyst is maintained above the predetermined temperature. . In addition, since the catalyst heating state is shifted to the maintenance state when the catalyst outlet temperature becomes the second predetermined temperature or lower, the catalyst heating state is temporarily shifted to the maintenance state, and then the catalyst heating state is shifted again. When the transition to the maintenance state is made, it is possible to make the factor of switching that the outlet temperature has been lowered only by the heating by the combustion of the combustion burner, and the outlet temperature excluding the inlet temperature can be changed by switching between the catalyst heating state and the maintenance state. It becomes possible to reliably prevent the temperature and the like from exceeding the heat resistance temperature of the catalyst. Since such heating is repeated as long as the catalyst needs to be heated, the temperature difference between the inlet temperature and the outlet temperature is reduced to increase the temperature of the entire catalyst, and the entire catalyst is maintained at a predetermined temperature. Make it possible.

  According to another aspect of the present invention, when the catalyst needs to be heated and the catalyst inlet temperature is lower than the predetermined temperature or the inlet / outlet temperature difference is smaller than the predetermined temperature difference. Can be brought into the catalyst heating state, and maintained when the catalyst inlet temperature is equal to or higher than the predetermined temperature and the inlet / outlet temperature difference is equal to or higher than the predetermined temperature difference. In addition, since the catalyst heating state is shifted to the maintenance state when the inlet / outlet temperature difference becomes equal to or greater than the predetermined temperature difference, the temperature taking into account the difference in speed between the temperature rise of the inlet temperature and the temperature drop of the outlet temperature. Control is performed to increase the inlet temperature and the outlet temperature, and even if the catalyst heating state and the maintenance state are repeatedly performed, it is possible to reliably prevent the heat resistance temperature of the catalyst from being exceeded. Since such heating is repeated as long as the catalyst needs to be heated, the temperature difference between the inlet temperature and the outlet temperature is reduced to increase the temperature of the entire catalyst, and the entire catalyst is maintained at a predetermined temperature. Make it possible.

  According to still another aspect of the present invention, when the catalyst needs to be heated and the catalyst inlet temperature is lower than the predetermined temperature, the catalyst is heated, and the catalyst inlet temperature is predetermined. When the temperature is higher than the temperature and the catalyst is already heated, the maintenance state can be established if the time has passed for a predetermined time. Since the catalyst heating state is shifted from the catalyst heating state to the maintenance state when the catalyst heating time exceeds a predetermined time, it is based on the amount of heat supplied to the catalyst by considering the catalyst heating time using the combustion burner. Temperature control becomes possible. Since such heating is repeated as long as the catalyst needs to be heated, the temperature difference between the inlet temperature and the outlet temperature is reduced, the minimum temperature of the catalyst is increased, and the entire catalyst is maintained at a predetermined temperature. Make it possible.

  Hereinafter, a specific embodiment of a control method for an exhaust gas purification apparatus for an internal combustion engine according to the present invention will be described based on the drawings.

  FIG. 1 is a block diagram showing the configuration of an exhaust gas purification apparatus control method for an internal combustion engine according to the present invention, and shows an example applied to a diesel engine 1 as an internal combustion engine. The diesel engine 1 is supplied with fresh air through an intake pipe 2 after dust and dust are removed by an air filter (not shown). Then, the fuel is combusted in the combustion chamber, and the exhaust gas is guided through the exhaust pipe 3 to the DPR 4 equipped with a catalyst as an exhaust purification device.

  Here, the DPR 4 includes a filter that captures PM, and an oxidation catalyst is supported in the filter. That is, this filter is composed of a ceramic material carrier having a honeycomb-shaped integrated structure carrying porous and high surface area alumina material on the surface, and platinum, which is a catalyst, is carried on this carrier. Yes. The DPR 4 includes a temperature sensor 7 that measures the inlet temperature of the catalyst of the DPR 4 and a temperature sensor 8 that measures the outlet temperature thereof.

  In addition, the combustion gas generated by the combustion burner 5 is led to the DPR 4 together with the exhaust gas of the diesel engine 1 from the upstream side. The combustion burner 5 is connected to a small air pump 51 having a check valve 52 on the discharge side and a fuel pump 53 that pressurizes and supplies fuel from a fuel tank (not shown). It is connected to the exhaust pipe 3. The combustion burner 5 is configured so that air is supplied from the air pump 51 and fuel is supplied from the fuel pump 53, and is ignited by a spark plug (not shown) to start combustion. The combustion gas generated in the combustion burner 5 is introduced into the exhaust pipe 3 through the pipe 54 and flows into the DPR 4. And the combustion gas which flowed into DPR4 heats the catalyst carry | supported in DPR4. Note that combustion gas, unburned fuel, and air can be supplied to the exhaust pipe 3 from the combustion burner 5 under the control of the ECU 6 described later.

  On the other hand, the internal combustion engine exhaust purification apparatus according to the present invention includes an electronic control unit (ECU) 6 that performs basic control such as engine fuel injection control in addition to control of the combustion burner 5. The ECU 6 is composed of, for example, a microcomputer including a CPU, a memory for recording various programs and data, an input interface circuit, and an output interface circuit. The input interface circuit is connected to temperature sensors 7 and 8 and sensors (not shown) which are means for detecting the operating state of the engine such as the engine speed and load via electric wiring. The ECU 6 can detect or calculate the rotational speed and load of the diesel engine 1 to obtain an operating state. On the other hand, the output interface circuit is connected to an air pump 51, a fuel pump 53, and the like, and combustion of the combustion burner 5 can be controlled from an ECU 6 described later.

  An example of the control of the combustion burner 5 for the exhaust gas purification apparatus for an internal combustion engine having the above configuration will be described with reference to the flowchart of FIG. Note that the exhaust gas purification control routine of FIG. 2 is a routine that is executed every predetermined time.

  First, the ECU 6 starts the exhaust purification control routine of FIG. Therefore, the ECU 6 first determines whether or not the catalyst needs to be heated in step S101. Whether the catalyst needs to be heated depends on whether the accumulated value of the amount of PM trapped in the DPR 4 estimated based on the operation state of the diesel engine 1 exceeds a predetermined amount, or the operation state of the diesel engine 1 in a specific region. For example, whether the catalyst temperature is equal to or lower than the predetermined temperature, whether the exhaust gas temperature of the exhaust gas from the diesel engine 1 is equal to or lower than the predetermined temperature, and the like. If it is determined that heating of the catalyst is not necessary, the process proceeds to step S107. When it is determined that the catalyst needs to be heated, the process proceeds to step S102.

  Therefore, if it is determined in step S101 that the catalyst needs to be heated, the process proceeds to step S102, where the ECU 6 determines whether or not the catalyst inlet temperature is equal to or higher than the first predetermined temperature T1. Specifically, it is determined whether or not the catalyst inlet temperature obtained from the input signal value sent to the input interface circuit by the temperature sensor 7 of the DPR 4 is equal to or higher than the first predetermined temperature T1. In the first embodiment, the first predetermined temperature T1 is set to 500 ° C., for example. Then, the ECU 6 proceeds to step S103 when the inlet temperature is equal to or higher than the first predetermined temperature T1. On the other hand, when the inlet temperature is lower than the first predetermined temperature T1, the routine proceeds to step S109, where the combustion burner 5 is ignited and put into a combustion state as will be described later.

  Next, as a result of the determination in step S102 described above, when the catalyst inlet temperature is equal to or higher than the first predetermined temperature T1, the process proceeds to step S103, and the ECU 6 determines that “the catalyst outlet temperature is the second predetermined temperature. It is determined whether or not T2 or less. Specifically, it is determined whether or not the catalyst outlet temperature obtained from the input signal value sent to the input interface circuit by the temperature sensor 8 of the DPR 4 is equal to or lower than the second predetermined temperature T2. In the first embodiment, the second predetermined temperature T2 is in principle lower than the first predetermined temperature T1, for example, 300 ° C. Then, when the outlet temperature is equal to or lower than the second predetermined temperature T2, the ECU 6 proceeds to step S104. On the other hand, when the outlet temperature is higher than the second predetermined temperature T2, the routine proceeds to step S109, where the combustion burner 5 is ignited. In other words, even if the catalyst inlet temperature is lower than the first predetermined temperature T1 in the determination in step S102 described above, or the catalyst inlet temperature is equal to or higher than the first predetermined temperature T1 in the determination in step S102 described above, in step S103. If it is determined that the outlet temperature of the catalyst is higher than the second predetermined temperature T2, the combustion burner 5 is ignited in step S109 to be in a combustion state, and thus is in a catalyst heating state. The catalyst heating state refers to a state where the catalyst is heated in a combustion state where air and fuel are supplied by the combustion burner 5. However, when the ECU 6 determines that the combustion burner 5 is already in combustion, that is, in a combustion state by a flame sensor (not shown) provided in the combustion burner 5, the ECU 6 maintains that state without igniting.

  Therefore, if the result of determination in steps S102 and S103 is that the catalyst inlet temperature is equal to or higher than the first predetermined temperature T1 and the catalyst outlet temperature is equal to or lower than the second predetermined temperature T2, the routine proceeds to step S104, where the ECU 6 Determines whether or not the combustion burner is in a combustion state. Specifically, it is determined from the input signal value sent from the flame sensor to the input interface circuit whether or not it is in a combustion state. When it is in the combustion state, the routine proceeds to step S105, the combustion of the combustion burner 5 is stopped, and then the supply of only fuel is started in step S106. On the other hand, when the combustion burner 5 is not in the combustion state, the process proceeds to step S106, and the supply of only fuel is started. At the start of the fuel supply, some air may be supplied to the combustion burner 5, but it is discharged from the combustion burner 5 without being combusted by the combustion burner 5, and is used for catalytic combustion in the catalyst. The amount of fuel consumed is supplied. Thus, this catalytic combustion maintains the catalyst temperature above a certain temperature. Hereinafter, this is referred to as a maintenance state.

  On the other hand, if it is determined in step S101 that heating of the catalyst is unnecessary, the process proceeds to step S107, where the ECU 6 determines whether or not the combustion burner is operating. When the combustion burner 5 is operating, the ECU 6 proceeds to step S108 and performs a stop process of the combustion burner 5. On the other hand, when the combustion burner 5 is not operating, this control routine is temporarily terminated.

  Next, a second embodiment of the control method for the exhaust gas purification apparatus for an internal combustion engine according to the present invention will be described. Moreover, since the hardware configuration in the second embodiment is the same as the configuration of the first embodiment of FIG. Therefore, an example of a control routine of the combustion burner 5 for the exhaust gas purification apparatus of the internal combustion engine in the second embodiment will be described. The exhaust gas purification control routine of the second embodiment is the above-described first exhaust gas control routine shown in FIG. Only the processing in step S103 of the exhaust purification control routine of the embodiment is different, and an inlet / outlet temperature difference (inlet temperature−outlet temperature), which is a difference between the catalyst inlet temperature and the outlet temperature, is used instead of the catalyst outlet temperature. It is said. Only this difference will be described as step S103 ′. Note that the first predetermined temperature T1, which is the reference for determining the catalyst inlet temperature in step S102 of the exhaust purification control routine of the second embodiment, is simply set to the predetermined temperature T1, for example, 500 ° C. in the second embodiment. Yes.

  In step S102, the catalyst inlet temperature is equal to or higher than the predetermined temperature T1, and when the routine proceeds to step S103 ′, in step S103 ′, the ECU 6 determines whether or not the inlet / outlet temperature difference is equal to or higher than the predetermined temperature difference T3. To do. Specifically, whether or not the inlet / outlet temperature difference, which is the difference between the inlet temperature obtained using the temperature sensor 7 of the DPR4 and the outlet temperature obtained using the temperature sensor 8 of the DPR4, is equal to or greater than a predetermined temperature difference T3. A determination is made. In the second embodiment, the predetermined temperature difference T3 is set to 200 ° C., for example. Then, the ECU 6 proceeds to step S104 when the inlet / outlet temperature difference is equal to or greater than the predetermined temperature difference T3. On the other hand, when the inlet / outlet temperature difference is smaller than the predetermined temperature difference T3, the routine proceeds to step S109, where the combustion burner 5 is ignited to be in a combustion state. When the ECU 6 determines that the combustion burner 5 is already in the combustion state by the flame sensor, the ECU 6 keeps the state without igniting.

  Next, a third embodiment of the control method for the exhaust gas purification apparatus for an internal combustion engine according to the present invention will be described. Moreover, since the hardware configuration in the third embodiment is the same as the configuration of the first embodiment in FIG. 1, the description thereof is omitted. Therefore, an example of the control routine of the combustion burner 5 for the exhaust gas purification apparatus of the internal combustion engine in the third embodiment will be described. The exhaust gas purification control routine of the third embodiment shown in FIG. 3 is shown in FIG. Further, the processing in step S103 and step S104 of the exhaust purification control routine of the first embodiment is different. Specifically, if the combustion burner 5 is in the combustion state instead of the catalyst outlet temperature, the combustion is performed. The catalyst heating time in which the burner 5 is ignited and the catalyst is heated in the combustion state is used. Only this difference will be described as step S103 ″ and step S104 ″. In the third embodiment, the first predetermined temperature T1, which is a reference for determining the catalyst inlet temperature in step S102 of the exhaust purification control routine, is simply set as the predetermined temperature T1 in the third embodiment, for example, 500 ° C. It is said. Here, the catalyst heating time means a continuous heating time in a catalyst heating state in which the combustion burner 5 is ignited to be in a combustion state and the catalyst is heated with the combustion heat.

  Since the inlet temperature of the catalyst is equal to or higher than the predetermined temperature T1 in step S102, when the process proceeds to step S103 ″, the ECU 6 determines in step S103 ″ “whether the combustion burner is in a combustion state”. This determination is performed using a flame sensor as in step S104. When it is in the combustion state, the process proceeds to step S104 ″, and when it is not in the combustion state, the process proceeds to step S106 to supply only fuel.

  When it is determined in step S103 ″ that the combustion state is present and the process proceeds to step S104 ″, in step S104 ″, the ECU 6 determines whether “the catalyst heating time is equal to or longer than a predetermined time t”. Specifically, the ECU 6 measures a catalyst heating time from when the combustion burner 5 is ignited by a timer device (not shown) that is a means for measuring time, and counts up the predetermined time t. Comparison with the heating time is performed to determine whether or not the catalyst heating time has exceeded a predetermined time. However, in the third embodiment, the predetermined time t is 30 seconds. Then, when the catalyst heating time is equal to or longer than the predetermined time t, the ECU 6 proceeds to step S105. On the other hand, when the catalyst heating time is shorter than the predetermined time t, this control routine is once ended. The predetermined time t is desirably set arbitrarily from 15 seconds to 30 seconds.

  The operation of the control method of the exhaust gas purification apparatus for an internal combustion engine according to the present invention described above according to the embodiment will be further described with reference to FIGS. First, when the catalyst needs to be heated, for example, the combustion burner 5 is ignited to be in a combustion state, and the combustion heat is supplied to the catalyst so that the catalyst is heated. As a result, for example, as shown by a combustion burner combustion curve A in FIG. 4, the catalyst is heated so that the inlet temperature of the catalyst reaches a predetermined temperature T1 or higher. Thereafter, the combustion burner 5 is misfired, and only unburned fuel is supplied from the combustion burner 5 to the catalyst to cause catalytic combustion to be maintained. As a result, as shown by the curve B of the fuel supply after combustion burner in FIG. 4, the inlet temperature becomes lower than the predetermined temperature T1, but the outlet temperature of the catalyst rises. Then, by switching between the catalyst heating state and the maintenance state alternately depending on at least whether or not the inlet temperature is equal to or higher than a predetermined temperature, the inlet temperature and the outlet temperature of the catalyst are substantially reduced as illustrated in FIG. While raising the temperature to the same temperature, while keeping the whole catalyst below the heat resistant temperature of the catalyst, it is possible to heat the whole catalyst and maintain the temperature of the whole catalyst at a predetermined temperature or higher.

  As mentioned above, although the control method of the exhaust gas purification device for an internal combustion engine according to the present invention has been described based on the preferred embodiments, the present invention includes different combinations of these embodiments. The present invention is not limited to these embodiments.

Specifically, the present invention provides catalysts as alkali metals such as potassium K, sodium Na, lithium Li and cesium Cs, alkaline earth metals such as barium Ba and calcium Ca, lanthanum La and yttrium Y. Rare earths and noble metals can be used. In addition to the DPR as the exhaust gas purification means of the internal combustion engine used in the first to third embodiments described above, the present invention provides a DPNR (Diesel Particulate-NOx Reduction system) that continuously purifies PM and NOx simultaneously. It is also possible to use exhaust gas purification means of an internal combustion engine such as the above.
In the first to third embodiments, the catalyst temperature is detected using a temperature sensor. However, the catalyst temperature may be estimated from the operating state of a diesel engine that is an internal combustion engine. Further, in the first to third embodiments, it has been described that when the catalyst heating state is shifted to the maintenance state, the combustion type burner is misfired, but the present invention is directed to the fuel and air during the misfire. This includes not only stopping the supply of fuel together, but also temporarily stopping only the fuel. Furthermore, in the first to third embodiments, the internal combustion engine is a diesel engine, but the present invention can also be applied to an exhaust gas purification device for a gasoline engine.

It is a figure which shows schematic structure of 1st embodiment of the control method of the exhaust gas purification device of the internal combustion engine which concerns on this invention. It is a flowchart which shows the exhaust gas purification control routine in 1st embodiment which concerns on this invention. It is a flowchart which shows the exhaust gas purification control routine in 3rd embodiment which concerns on this invention. It is the graph showing the relationship between the distance from the entrance of a catalyst, and catalyst temperature regarding two forms. It is the graph showing transition of the inlet temperature and outlet temperature of a catalyst regarding time.

Explanation of symbols

1 Diesel engine 2 Intake pipe 3 Exhaust pipe 4 DPR
5 Combustion burner 6 ECU
7, 8 Temperature sensor 51 Air pump 52 Check valve 53 Fuel pump 54 Piping

Claims (1)

A control method for an exhaust gas purification apparatus for an internal combustion engine, wherein the exhaust gas purification catalyst provided in the exhaust passage of the internal combustion engine is heated and controlled using a combustion burner,
When the catalyst needs to be heated,
When the inlet temperature of the catalyst is lower than a predetermined temperature, or when the inlet / outlet temperature difference, which is the difference between the inlet temperature and the outlet temperature of the catalyst, is smaller than the predetermined temperature difference, the combustion burner is supplied with fuel and air And burn
When the catalyst inlet temperature is not less than the predetermined temperature and the catalyst inlet / outlet temperature difference is not less than the predetermined temperature difference, the combustion burner is controlled to discharge at least fuel without burning. A control method for an exhaust gas purification device for an internal combustion engine.

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