JP2013253578A - Exhaust gas emission control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas emission control device for an internal combustion engine capable of preventing hazardous material release regardless of a long lasting low-temperature and inactive state of an occluding catalyst.SOLUTION: An exhaust gas emission control device for an internal combustion engine includes an occluding catalyst 17 disposed in an exhauster 4 of an internal combustion engine 1 and adsorbing hazardous materials, an adsorbed amount estimating means 18 estimating an amount of the hazardous materials adsorbed by the occluding catalyst, and a regeneration control means 19 executing regeneration control for removing the hazardous materials from the occluding catalyst based on the adsorbed amount of the hazardous materials estimated by the adsorbed amount estimating means. The exhaust gas emission control device includes an active state detection means detecting an active state of the occluding catalyst, and a forced regeneration means 21 executing the regeneration control when an inactive state of the occluding catalyst is detected by the active state detection means and the occluding catalyst is determined to be in a saturated state based on the adsorbed amount of the hazardous materials estimated by the adsorbed amount estimating means.

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, and more particularly, a harmful substance is temporarily adsorbed on a storage catalyst provided in the exhaust apparatus, and when the storage catalyst becomes saturated, the regeneration process is performed to remove the harmful substance. The present invention relates to an exhaust emission control device for an internal combustion engine.

2. Description of the Related Art Some exhaust gas purification apparatuses for internal combustion engines include a storage catalyst that adsorbs and purifies NOx and particulates (particulate matter such as carbon) that are covered components in exhaust such as gasoline engines and diesel engines. .
For example, as an exhaust purification device, the exhaust device is equipped with a storage catalyst that adsorbs NOx, which is a harmful substance, and when the internal combustion engine is in a lean combustion state, NOx in the exhaust is adsorbed on the storage catalyst, and then the combustion state is rich. Then, CO and HC contained in the exhaust gas and NOx occluded in the occlusion catalyst are reacted (reduced) to purify and regenerate the occlusion catalyst. (For example, Patent Document 1)
In the exhaust purification device of this Patent Document 1, when NOx is excessively adsorbed by the storage catalyst, it becomes saturated, and thereafter NOx is not adsorbed by the storage catalyst and is discharged from the exhaust device. For this reason, in order to estimate how much NOx is adsorbed by the storage catalyst, the exhaust purification device described above adsorbs NOx per unit time based on the rotational speed and load of the internal combustion engine (intake pressure of the surge tank). Seeking the amount. (Paragraph [0027] of description)
In addition, an exhaust purification device equipped with an occlusion catalyst that adsorbs and collects particulates that are harmful substances to the exhaust device, adsorbs particulates in the exhaust gas to the occlusion catalyst when the internal combustion engine is in a lean combustion state. Some of them regenerate the storage catalyst by burning and purifying the particulates deposited on the storage catalyst. (For example, Patent Document 2)
In the exhaust emission control device of Patent Document 2, the vehicle is guided to the road where the exhaust temperature is sufficiently high and the particulates are surely removed by natural combustion in consideration of the traveling state of the vehicle. Promoting the purification process. (Paragraph [0008] of the description)

JP-A-8-14030 JP 2010-216323 A

By the way, in the exhaust gas purification apparatus as in the above-mentioned Patent Document 1, the storage catalyst that adsorbs NOx as a harmful substance in a lean state and purifies by reduction in a rich state becomes inactive when the temperature is low, and the purification capacity is reduced. There is a characteristic to do. For this reason, the exhaust purification device is controlled so that the adsorbed NOx is not exhausted from the exhaust device when the storage catalyst is in a low temperature state, and is adsorbed while maintaining the lean combustion state.
However, in recent years, in vehicles equipped with a so-called idling stop function, there are many opportunities for the internal combustion engine to stop, and the NOx adsorption amount of the storage catalyst becomes saturated before warming up of the internal combustion engine is completed, so that NOx becomes a storage catalyst. There was a risk of exhaustion from the exhaust system without being adsorbed.
Similarly, in the exhaust gas purification apparatus as described in Patent Document 2, in a vehicle having a so-called idling stop function, there are many opportunities for the internal combustion engine to stop, so before the warm-up of the internal combustion engine is completed. There is a possibility that the particulate accumulation amount of the storage catalyst becomes saturated, and the particulates are not adsorbed by the storage catalyst and are discharged from the exhaust device.

  Therefore, the present invention has been made in view of the above problems, and provides an exhaust gas purification apparatus for an internal combustion engine that can prevent discharge of harmful substances even when the storage catalyst is in an inactive state at a low temperature for a long period of time. For the purpose.

  The present invention is estimated by an occlusion catalyst that is provided in an exhaust device of an internal combustion engine and adsorbs harmful substances, an adsorption amount estimation means that estimates the amount of harmful substances adsorbed on the occlusion catalyst, and the adsorption amount estimation means. An exhaust gas purification apparatus for an internal combustion engine having a regeneration control means for executing regeneration control for removing harmful substances from the storage catalyst based on an adsorption amount of the harmful substances, wherein the exhaust purification device detects an active state of the storage catalyst The inactive state of the storage catalyst is detected by the active state detection means and the active state detection means, and the storage catalyst is determined to be saturated based on the amount of adsorption of the harmful substance estimated by the adsorption amount estimation means. And a forced regeneration means for executing the regeneration control.

  Even if the storage catalyst is in an inactive state for a long period of time, the storage catalyst is forcibly regenerated when the amount of harmful substances adsorbed on the storage catalyst becomes saturated. The adsorption amount of the storage catalyst becomes saturated, and it can be prevented that harmful substances are discharged without being adsorbed. In addition, when the storage catalyst is regenerated in a low temperature state, harmful substances are discharged, but since the amount is slight compared with the amount discharged in a saturated state, the amount of harmful substances discharged can be suppressed. .

FIG. 1 is a block diagram of an exhaust gas purification apparatus for an internal combustion engine. Example 1 FIG. 2 is a system diagram at the time of NOx adsorption by the exhaust purification device of the internal combustion engine. Example 1 FIG. 3 is a system diagram at the time of NOx purification by the exhaust gas purification apparatus of the internal combustion engine. Example 1 FIG. 4 is a logic circuit diagram of NOx processing by the exhaust gas purification apparatus for an internal combustion engine. Example 1 FIG. 5 is a flow chart of NOx processing by the exhaust gas purification apparatus for an internal combustion engine. Example 1 FIG. 6 is a NOx concentration map for obtaining the NOx concentration from the engine speed and the fuel injection amount. Example 1 FIG. 7 is a NOx integrated rate map for obtaining the NOx integrated rate from the NOx concentration and the elapsed time after engine start. Example 1 FIG. 8 is a saturation storage time map for obtaining the saturation storage time of the storage catalyst according to the value of the NOx concentration. Example 1 FIG. 9 is a block diagram of an exhaust purification device for an internal combustion engine. (Example 2) FIG. 10 is a system diagram of the particulate processing by the exhaust gas purification device of the internal combustion engine. (Example 2) FIG. 11 is a flowchart of the particulate processing performed by the exhaust gas purification apparatus for the internal combustion engine. (Example 2) FIG. 12 is a deposition rate map for obtaining the particulate deposition rate from the engine speed and the fuel injection amount. (Example 2) FIG. 13 is a cumulative accumulation rate map for obtaining the cumulative particulate accumulation rate from the particulate deposition rate and the elapsed time after engine start. (Example 2) FIG. 14 is a saturation deposition time map for obtaining the saturation deposition time of the storage catalyst in accordance with the particulate deposition rate. (Example 2)

  Embodiments of the present invention will be described below with reference to the drawings.

1 to 8 show Embodiment 1 of the present invention. In FIG. 1, 1 is an internal combustion engine, 2 is a combustion chamber, 3 is an intake device, and 4 is an exhaust device. An internal combustion engine 1 mounted on a vehicle is a gasoline engine or a diesel engine. As an intake device 3, an intake passage 5 communicating with a combustion chamber 2 is provided, and a throttle valve 6 is provided in the intake passage 5. In addition, the internal combustion engine 1 is provided with an exhaust passage 7 communicating with the combustion chamber 2 as the exhaust device 4. The internal combustion engine 1 includes a fuel injection device 8 that injects and supplies fuel. The fuel injection device 8 is provided with a fuel injection valve 9 that supplies fuel to the internal combustion engine 1.
In the fuel injection device 8, the fuel injection amount of the fuel injection valve 9 is controlled by the fuel injection amount calculation means 11 of the control device 10. The fuel injection amount calculating means 11 includes an outside air temperature detected by the outside air temperature sensor 12, an atmospheric pressure detected by the atmospheric pressure sensor 13, an intake air amount detected by the intake air amount sensor 14 (or an intake air pressure detected by the intake air pressure sensor), With reference to the engine speed of the internal combustion engine 1 detected by the crank angle sensor 15, the fuel injection amount is calculated based on the engine speed and the intake air amount (or intake air pressure) indicating the load while taking the outside air temperature and atmospheric pressure into consideration. .
The fuel injection amount is determined according to the engine speed detected by the crank angle sensor 15 and the intake air amount detected by the intake air sensor 14. At this time, if the outside air temperature is low, the amount of oxygen contained in the intake air increases, so that the fuel injection amount is controlled to decrease according to the amount of oxygen. Further, when the atmospheric pressure is low, the amount of oxygen in the intake air decreases, so the fuel injection amount increases. That is, the fuel injection amount is increased or decreased according to changes in the outside air temperature and the atmospheric pressure so as to obtain an appropriate output.
The fuel injection device 8 operates the fuel injection valve 9 so as to achieve the fuel injection amount calculated by the fuel injection amount calculation means 11 and injects and supplies the fuel to the intake passage 5. The internal combustion engine 1 burns an air-fuel mixture of air supplied through the intake passage 5 and fuel supplied from the fuel injection valve 9 in the combustion chamber 2 to generate driving force. The exhaust after combustion is discharged to the outside through the exhaust passage 7.

The internal combustion engine 1 is provided with an exhaust purification device 16 that purifies exhaust. The exhaust purification device 16 includes a storage catalyst 17 that adsorbs NOx, which is a harmful substance in exhaust gas, to the exhaust passage 7 and purifies the stored NOx. The exhaust purification device 16 estimates the amount of NOx adsorbed and stored by the storage catalyst 17 (NOx adsorption amount), and the storage catalyst 17 based on the NOx adsorption amount estimated by the adsorption amount estimation means 18. The control device 10 is provided with a regeneration control means 19 for performing regeneration control for removing NOx from the control device 10.
When the internal combustion engine 1 is in a lean combustion state, the exhaust purification device 16 adsorbs NOx in the exhaust to the storage catalyst 17 according to the NOx storage chemical reaction formula shown in the formula (R1) as shown in FIG. . Thereafter, the exhaust purification device 16 determines whether or not the NOx adsorption amount of the storage catalyst 17 is saturated based on the NOx adsorption amount of the storage catalyst 17 estimated by the adsorption amount estimation unit 18 by the regeneration control unit 19. To do. When it is determined that the NOx adsorption amount of the storage catalyst 17 is in a saturated state, the regeneration control unit 19 executes regeneration control for removing NOx from the storage catalyst 17.
In the regeneration control, the fuel injection amount of the fuel injection valve 9 is increased (or the fuel is injected after the combustion stroke) to bring the internal combustion engine 1 into a rich combustion state, and as shown in FIG. 3, the NOx oxidation shown in the equation (R2) In accordance with the NOx reduction reaction equation shown in the reaction equation, equation (R3), CO and HC contained in the exhaust gas and NOx occluded in the occlusion catalyst 17 are reacted (reduced) and purified, and the occlusion catalyst 17 is regenerated. .

The exhaust purification device 16 of the internal combustion engine 1 includes a catalyst temperature sensor 20 that detects a catalyst temperature of the storage catalyst 17 as an active state detection unit that detects an active state of the storage catalyst 17 in the control device 10. The control device 10 includes a forced regeneration means 21 that performs regeneration control of the storage catalyst 17 based on the catalyst temperature detected by the catalyst temperature sensor 20. The forced regeneration means 21 detects the inactive state of the storage catalyst 17 when the catalyst temperature of the storage catalyst 17 detected by the catalyst temperature sensor 20 is lower than the activation temperature, and the storage catalyst estimated by the adsorption amount estimation means 18. When it is determined that the storage catalyst 17 is saturated based on the NOx adsorption amount of 17, the regeneration control is forcibly executed. In the regeneration control, as described above, the internal combustion engine 1 is brought into a rich combustion state, and CO and HC contained in the exhaust gas are reacted (reduced) with NOx occluded in the occlusion catalyst 17 to purify the occlusion catalyst 17. Is played back.
Further, the exhaust purification device 16 includes a time measuring means 22. The time measuring means 22 includes an engine start timer 23 for measuring an elapsed time since the start of the internal combustion engine 1 (hereinafter referred to as “elapsed time Te after engine start”), and an elapsed time (from when the regeneration control is stopped). (Hereinafter referred to as “elapsed time Tr after playback stop”), and a playback stop timer 24 for measuring. In the forced regeneration means 21, the elapsed time Te after the engine start measured by the engine start timer 23 becomes equal to or greater than the set value, or the elapsed time Tr after the regeneration stop measured by the regeneration stop timer 24 becomes equal to or greater than the set value. At this time, it is determined that the storage catalyst 17 is saturated.
The set values for determining the elapsed time Te after the engine start and the elapsed time Tr after the regeneration stop are calculated by the saturated storage time calculating means 25. As shown in FIG. 8, the saturated storage time calculating means 25 is a threshold at which the NOx adsorption amount of the storage catalyst 17 becomes saturated according to the NOx concentration (solid line) before entering the storage catalyst 17 based on the saturated storage time map. The time to reach (broken line) is calculated as the saturated storage time Ts. The forced regeneration means 21 uses the saturation storage time Ts calculated by the saturation storage time calculation means 25 as a set value, and when the elapsed time Te after engine start becomes equal to or greater than the saturation storage time Ts that is the set value, or after the regeneration has stopped. When the time Tr becomes equal to or longer than the saturation storage time Ts that is the set value, it is determined that the storage catalyst 17 is in a saturated state.
Further, the exhaust purification device 16 includes a storage unit 26 in the control device 10. The storage means 26 stores a NOx concentration map (FIG. 6) for obtaining the NOx concentration before entering the storage catalyst 17 from the fuel injection amount and the engine speed, the NOx concentration obtained from the NOx concentration map, and the engine of the internal combustion engine 1. The NOx integrated rate map (FIG. 7) for determining the NOx integrated rate (the ratio between the NOx concentration and time) from the elapsed time Te after starting, and the NOx of the storage catalyst 17 in accordance with the value of the NOx concentration determined by the NOx concentration map. A saturated occlusion time map (FIG. 8) for determining the saturated occlusion time Ts until the adsorption amount reaches a threshold value for saturation is stored. The exhaust purification device 16 calculates various set values for determination from the NOx concentration map (FIG. 6), the NOx integrated rate map (FIG. 7), and the saturated storage time map (FIG. 8).

Next, the operation will be described.
As shown in FIG. 5, the exhaust purification device 16 of the internal combustion engine 1 starts control by the control device 10 (A01), and when the internal combustion engine 1 is started by turning on the ignition switch (A02), the engine start timer 23 Thus, the measurement of the elapsed time Te after the engine start is started (A03), and the fuel injection amount calculated by the fuel injection amount calculation means 11 and the engine speed detected by the crank angle sensor 15 are acquired (A04).
Based on the NOx concentration map (see FIG. 6), the NOx concentration corresponding to the obtained fuel injection amount and engine speed is obtained (A05), and based on the NOx integrated rate map (see FIG. 7), the NOx concentration map is used. A NOx integrated rate corresponding to the value of the obtained NOx concentration rate curve and the elapsed time Te after engine start measured by the start timer 23 is obtained. (A06)
The NOx concentration obtained by the NOx concentration map is multiplied by the NOx integrated rate obtained by the NOx integrated rate map to calculate the NOx adsorbed amount adsorbed by the storage catalyst 17 (NOx adsorbed amount = NOx concentration × NOx integrated rate). (A07). Then, based on the saturated storage time map (see FIG. 8), the saturated storage time Ts is obtained from the NOx concentration straight line corresponding to the value of the NOx concentration obtained from the NOx concentration map and the threshold value of the NOx adsorption amount (A08). The NOx adsorption amount is obtained by the adsorption amount estimating means 21. The saturated storage time Ts is obtained by the saturated storage time calculation means 25.

After calculating the NOx adsorption amount (A07) and calculating the saturated storage time Ts (A08), it is determined whether the storage catalyst 17 is in an active state based on the catalyst temperature detected by the catalyst temperature sensor 20 (A09). The catalyst temperature sensor 20 for determining the active state of the storage catalyst 17 can be replaced by a temperature sensor that measures the water temperature of the radiator.
If the determination whether the storage catalyst 17 is in the active state (A09) is YES, it is determined whether the NOx adsorption amount adsorbed on the storage catalyst 17 is equal to or greater than the threshold value at which the storage catalyst 17 is saturated (NOx adsorption amount ≧ threshold value). (A10). As shown in FIG. 8, the NOx adsorption amount differs in the saturated storage time Ts until reaching the saturation threshold value according to the NOx concentration line, and the saturation storage time Ts until reaching the threshold value becomes shorter as the NOx concentration becomes higher. Become.
If this determination (A10) is NO, the process returns to obtaining the fuel injection amount and the engine speed (A04). If this determination (A10) is YES, regeneration control for removing NOx from the storage catalyst 17 is executed by the regeneration control means 19 (A11), and it is determined whether the execution time of regeneration control has passed a predetermined time (A12). ).
If this determination (A12) is NO, the regeneration control (A11) is continued. When this determination (A12) is YES, the regeneration control is stopped (A13), the regeneration stop timer 24 starts to measure the elapsed time Tr after the regeneration stop (A14), and the engine speed and the fuel injection amount are acquired. Return to (A04).
On the other hand, if the determination as to whether the storage catalyst 17 is in the active state (A09) is NO, whether the elapsed time Te after the engine start is equal to or longer than the saturated storage time Ts (Te ≧ Ts), or regeneration of the regeneration control It is determined whether the elapsed time Tr after the stop is equal to or longer than the saturated storage time Ts (Tr ≧ Ts) (A15).
When this determination (A15) is NO, the process returns to obtaining the fuel injection amount and the engine speed (A04). If this determination (A15) is YES, the process proceeds to execution of regeneration control (A11) in which NOx is removed from the storage catalyst 17 by the forced regeneration means 21, the above-mentioned determination (A12) to processing (A14) are performed, and the engine rotation is performed. Return to the acquisition of the number and the fuel injection amount (A04).
In other words, the exhaust purification device 16 has the storage catalyst 17 until the storage catalyst 17 is activated (A09: NO) by the elapsed time Te after the engine start of the internal combustion engine 1 or the elapsed time Tr after the regeneration stop of the regeneration control. Is determined to be saturated or not, and if the storage catalyst 17 is saturated, regeneration control is executed. On the other hand, the exhaust purification device 16 determines whether or not the storage catalyst 17 is saturated by the NOx adsorption amount taking into account the aging of the storage catalyst 17 after the storage catalyst 17 is activated (A09: YES). Determine (A10).
Accordingly, as shown in FIG. 4, the exhaust purification device 16 is configured such that when the NOx adsorption amount becomes equal to or greater than the threshold value at which saturation occurs, the elapsed time Te after engine start or the elapsed time Tr after regeneration stop is the saturated adsorption time. When the temperature becomes equal to or higher than Ts, regeneration control for purifying NOx stored in the storage catalyst 17 and regenerating the storage catalyst 17 is executed.

Thus, in the exhaust gas purification device 16 of the internal combustion engine 1, the forced regeneration means 21 detects the inactive state of the storage catalyst 17 by the catalyst temperature sensor 20, and the NOx adsorption amount estimated by the adsorption amount estimation means 21 is obtained. Based on this, when it is determined that the NOx adsorption amount of the storage catalyst 17 is saturated, regeneration control is executed.
As a result, the exhaust purification device 16 forces the storage catalyst 17 when the amount of NOx adsorbed by the storage catalyst 17 becomes saturated even if the storage catalyst 17 remains in an inactive state at a low temperature for a long period of time. Therefore, it is possible to prevent the NOx from being exhausted without being adsorbed because the storage catalyst 17 is saturated when inactive. In addition, when the storage catalyst 17 performs the regeneration process in a low temperature state, NOx is discharged. However, since the amount is small compared with the amount discharged due to the saturated state of the storage catalyst 17, it is possible to suppress the discharge amount. it can.
Further, in a vehicle that stops the internal combustion engine 1 a plurality of times in a short period of time (so-called idling stop vehicle), fluctuations in the engine load and engine speed of the internal combustion engine 1 are large, and the storage catalyst is based on these values. If the NOx adsorption amount of 17 is estimated, an error is likely to occur in the estimation of the NOx adsorption amount.
Therefore, the exhaust purification device 16 estimates the NOx adsorption amount by the forced regeneration means 19 based on the elapsed time Te after the engine start of the internal combustion engine 1 or the elapsed time Tr after the regeneration stop of the regeneration control, and sets the saturation state of the storage catalyst 17. Therefore, no error occurs in the estimation of the NOx adsorption amount, the saturation state of the storage catalyst 17 can be accurately determined, and the regeneration control can be executed reliably.

9 to 14 show Embodiment 2 of the present invention. In FIG. 9, 101 is an internal combustion engine, 102 is a combustion chamber, 103 is an intake device, and 104 is an exhaust device. An internal combustion engine 101 mounted on a vehicle is a diesel engine. As an intake device 103, an intake passage 105 communicating with a combustion chamber 102 is provided, and a throttle valve 106 is provided in the intake passage 105. In addition, the internal combustion engine 101 is provided with an exhaust passage 107 communicating with the combustion chamber 102 as the exhaust device 104. The internal combustion engine 101 includes a fuel injection device 108 that injects and supplies fuel. The fuel injection device 108 is provided with a fuel injection valve 109 that supplies fuel to the internal combustion engine 101.
In the fuel injection device 108, the fuel injection amount of the fuel injection valve 109 is controlled by the fuel injection amount calculation means 111 of the control device 110. The fuel injection amount calculating means 111 includes an outside air temperature detected by the outside air temperature sensor 112, an atmospheric pressure detected by the atmospheric pressure sensor 113, an intake air amount detected by the intake air amount sensor 114 (or an intake air pressure detected by the intake air pressure sensor), With reference to the engine speed of the internal combustion engine 1 detected by the crank angle sensor 115, the fuel injection amount is calculated based on the engine speed and the intake air amount (or intake air pressure) indicating the load while taking the outside air temperature and atmospheric pressure into consideration. .
The fuel injection amount is determined according to the engine speed detected by the crank angle sensor 115 and the intake air amount detected by the intake air sensor 114. At this time, if the outside air temperature is low, the amount of oxygen contained in the intake air increases, so that the fuel injection amount is controlled to decrease according to the amount of oxygen. Further, when the atmospheric pressure is low, the amount of oxygen in the intake air decreases, so the fuel injection amount increases. That is, the fuel injection amount is increased or decreased according to changes in the outside air temperature and the atmospheric pressure so as to obtain an appropriate output.
The fuel injection device 108 operates the fuel injection valve 109 so that the fuel injection amount calculated by the fuel injection amount calculation means 111 is obtained, and supplies the fuel to the intake passage 105 by injection. The internal combustion engine 101 burns the air-fuel mixture of the air supplied through the intake passage 105 and the fuel supplied through the fuel injection valve 109 in the combustion chamber 102 to generate driving force. The exhaust gas after combustion is discharged to the outside through the exhaust passage 107.

The internal combustion engine 101 is provided with an exhaust purification device 116 that purifies exhaust. The exhaust purification device 116 includes a storage catalyst (DPF: Diesel Particulate Filter) 117 that adsorbs particulates, which are harmful substances in exhaust gas, to the exhaust passage 107 and purifies the stored particulates. The exhaust purification device 116 estimates the amount of particulates adsorbed and deposited by the storage catalyst 117 (particulate deposition amount), and the particulate deposition amount estimated by the deposition amount estimation unit 118. The control device 110 is provided with regeneration control means 119 for performing regeneration control for removing particulates from the storage catalyst 117.
The exhaust purification device 116 adsorbs particulates in the exhaust to the storage catalyst 117 when the internal combustion engine 101 is in a lean combustion state. Thereafter, the exhaust purification device 116 determines whether or not the particulate deposition amount of the storage catalyst 117 is saturated based on the particulate deposition amount of the storage catalyst 117 estimated by the regeneration amount estimation unit 118 by the regeneration control unit 119. Judging. When it is determined that the particulate accumulation amount of the storage catalyst 117 is saturated, the regeneration control unit 119 performs regeneration control for removing particulates from the storage catalyst 117.
In the regeneration control, as shown in FIG. 10, the fuel injection amount of the fuel injection valve 109 is increased (or the fuel is injected after the combustion stroke) to bring the internal combustion engine 101 into a rich combustion state and occluded by the fuel contained in the exhaust gas. The particulates stored in the catalyst 117 are burned and purified, and the storage catalyst 117 is regenerated. In the regeneration control, as shown in FIG. 10, a heater 117H is provided in the storage catalyst 117, and the particulate matter stored in the storage catalyst 117 is burned and purified by the heater 117H, and the storage catalyst 117 is regenerated. There is also.

The exhaust gas purification device 116 of the internal combustion engine 101 includes a catalyst temperature sensor 120 that detects the catalyst temperature of the storage catalyst 117 as an active state detection unit that detects the active state of the storage catalyst 117. The control device 110 includes a forced regeneration means 121 that performs regeneration control of the storage catalyst 117 based on the catalyst temperature detected by the catalyst temperature sensor 120. The forced regeneration means 121 detects the inactive state of the storage catalyst 117 when the catalyst temperature of the storage catalyst 117 detected by the catalyst temperature sensor 120 is lower than the activation temperature, and the storage catalyst estimated by the accumulation amount estimation means 118. When the storage catalyst 117 is determined to be saturated based on the particulate accumulation amount 117, regeneration control is forcibly executed. In the regeneration control, as described above, the internal combustion engine 101 is brought into a rich combustion state, and the particulate matter stored in the storage catalyst 117 is burned and purified by the fuel contained in the exhaust, or the particulate matter is burned by the heater 117H. Then, the storage catalyst 117 is regenerated.
Further, the exhaust purification device 116 includes a time measuring means 122. The time measuring means 122 includes an engine start timer 123 for measuring an elapsed time since the start of the internal combustion engine 101 (hereinafter referred to as “elapsed time Te after engine start”), and an elapsed time since the regeneration control was stopped ( (Hereinafter referred to as “elapsed time Tr after playback stop”) and a playback stop timer 124 for measuring. In the forced regeneration means 121, when the elapsed time Te after the engine start measured by the engine start timer 123 becomes equal to or greater than the set value, or the elapsed time Tr after the regeneration stop measured by the regeneration stop timer 124 becomes greater than or equal to the set value At this time, it is determined that the storage catalyst 117 is saturated.
The set values for determining the elapsed time Te after the engine start and the elapsed time Tr after the regeneration stop are calculated by the saturation deposition time calculation means 125. As shown in FIG. 14, the saturation deposition time calculation unit 125 saturates the particulate deposition amount of the storage catalyst 117 according to the particulate deposition rate (solid line) on the storage catalyst 117 based on the saturation deposition time map. The time until the threshold value (broken line) is reached is calculated as the saturation deposition time Ts. The forced regeneration means 121 uses the saturation deposition time Ts calculated by the saturation deposition time calculation means 125 as a set value, and when the elapsed time Te after the engine start becomes equal to or greater than the saturation deposition time Ts that is the set value, or after the regeneration stop. When the time Tr becomes equal to or longer than the saturation deposition time Ts that is the set value, it is determined that the storage catalyst 117 is in a saturated state.
Further, the exhaust purification device 116 includes a storage unit 126 in the control device 110. The storage means 126 stores a deposition rate map (FIG. 12) for determining the particulate deposition rate on the storage catalyst 117 from the fuel injection amount and the engine speed, the particulate deposition rate determined by the deposition rate map, and the internal combustion engine. Accumulated deposition rate map (FIG. 13) for determining the accumulated accumulation rate (ratio between the deposition rate of particulates and time) from the elapsed time Te after the engine start of the engine 1, and the deposition rate of the particulates determined by the deposition rate map The saturation deposition time map (FIG. 14) for obtaining the saturation deposition time Ts until the particulate deposition amount of the storage catalyst 117 reaches the threshold value for saturation is stored. The exhaust purification device 116 calculates various set values for determination from the deposition rate map (FIG. 12), the accumulated accumulation rate map (FIG. 13), and the saturation deposition time map (FIG. 14).

Next, the operation will be described.
As shown in FIG. 11, the exhaust purification device 116 of the internal combustion engine 101 starts control by the control device 110 (B01), and when the internal combustion engine 101 is started by turning on the ignition switch (B02), the engine start timer 123 is started. Thus, the measurement of the elapsed time Te after engine start is started (B03), and the fuel injection amount calculated by the fuel injection amount calculation means 111 and the engine speed detected by the crank angle sensor 115 are acquired (B04).
Based on the deposition rate map (see FIG. 12), the particulate deposition rate corresponding to the acquired fuel injection amount and engine speed is obtained (B05), and the deposition is based on the accumulated deposition rate map (see FIG. 13). A cumulative accumulation rate corresponding to the value of the rate curve of the deposition rate obtained from the speed map and the elapsed time Te after the engine start measured by the start timer 123 is obtained. (B06)
Multiplying the particulate deposition rate obtained by the deposition rate map by the particulate accumulation rate obtained by the deposition cumulative rate map, the amount of particulates adsorbed and deposited by the storage catalyst 117 is calculated ( (Particulate deposition amount = deposition rate × deposition integration rate) (B07). Then, based on the saturation deposition time map (see FIG. 14), the saturation deposition time Ts is obtained from the deposition rate straight line corresponding to the value of the deposition rate obtained from the deposition rate map and the threshold of the deposition amount (B08). The accumulated amount of particulates is obtained by the accumulated amount estimating means 121. The saturation deposition time Ts is obtained by the saturation deposition time calculation means 125.

After the calculation of the particulate deposition amount (B07) and the saturation deposition time Ts (B08), it is determined whether the storage catalyst 117 is in an active state based on the catalyst temperature detected by the catalyst temperature sensor 120 (B09). Note that the catalyst temperature sensor 120 for determining the active state of the storage catalyst 117 can be replaced by a temperature sensor that measures the water temperature of the radiator.
If the determination of whether the storage catalyst 117 is in the active state (B09) is YES, it is determined whether or not the accumulation amount of the particulate adsorbed on the storage catalyst 117 is equal to or greater than a threshold value at which the accumulation catalyst is saturated (deposition amount ≧ threshold value). Judgment is made (B10). As shown in FIG. 14, the amount of particulate deposition differs in the saturation deposition time Ts until the saturation threshold is reached according to the deposition rate line, and the saturation deposition time Ts until the threshold is reached as the deposition rate increases. Becomes shorter.
If this determination (B10) is NO, the process returns to obtaining the fuel injection amount and the engine speed (B04). When this determination (B10) is YES, regeneration control for removing particulates from the storage catalyst 117 is performed by the regeneration control means 119 (B11), and it is determined whether the execution time of regeneration control has passed a predetermined time ( B12).
If this determination (B12) is NO, the regeneration control (B11) is continued. If this determination (B12) is YES, the regeneration control is stopped (B13), the regeneration stop timer 124 starts measuring the elapsed time Tr after the regeneration stop (B14), and the engine speed and the fuel injection amount are acquired. Return to (B04).
On the other hand, if the determination as to whether the storage catalyst 117 is in an active state (B09) is NO, whether the elapsed time Te after engine start is equal to or greater than the saturated storage time Ts (Te ≧ Ts), or regeneration of regeneration control It is determined whether the elapsed time Tr after the stop is equal to or longer than the saturated storage time Ts (Tr ≧ Ts) (B15).
If this determination (B15) is NO, the process returns to obtaining the fuel injection amount and the engine speed (B04). When this determination (B15) is YES, the forced regeneration means 121 shifts to regeneration control execution (B11) in which the particulates are removed from the storage catalyst 117, and the above-described determination (B12) to processing (B14) are performed. The process returns to obtaining the rotation speed and the fuel injection amount (B04).
In other words, the exhaust purification device 116 has the storage catalyst 117 until the storage catalyst 117 is activated (B09: NO) by the elapsed time Te after the engine start of the internal combustion engine 101 or the elapsed time Tr after the regeneration stop of the regeneration control. Is determined to be saturated, and if the storage catalyst 117 is saturated, regeneration control is executed. On the other hand, after the activation of the storage catalyst 117 (B09: YES), the exhaust purification device 116 determines whether or not the storage catalyst 117 is in a saturated state based on the particulate accumulation amount considering the aging of the storage catalyst 117. Is determined (B110).
Thus, in the exhaust purification device 116, when the accumulated amount of particulates is equal to or greater than a threshold value that is saturated, the elapsed time Te after engine start or the elapsed time Tr after regeneration stop is equal to or greater than the saturated deposition time Ts. In this case, regeneration control for regenerating the storage catalyst 117 by purifying the particulates stored in the storage catalyst 117 is executed.

In this way, in the exhaust purification device 116 of the internal combustion engine 101, the forced regeneration means 121 detects the inactive state of the storage catalyst 117 by the catalyst temperature sensor 120, and the accumulated amount of particulates estimated by the accumulated amount estimation means 121. When it is determined that the particulate accumulation amount of the storage catalyst 117 is saturated based on the above, regeneration control is executed.
As a result, the exhaust purification device 116 forces the storage catalyst 117 when the amount of particulate adsorbed on the storage catalyst 117 becomes saturated even if the storage catalyst 117 is in an inactive state at a low temperature for a long period of time. Therefore, the storage catalyst 117 is saturated when inactive, and the particulates can be prevented from being discharged without being adsorbed. In addition, when the storage catalyst 117 performs the regeneration process in a low temperature state, the particulates are discharged. However, since the amount is small compared with the amount discharged due to the saturated state of the storage catalyst 117, the discharge amount is suppressed. Can do.
Further, in a vehicle that stops the internal combustion engine 101 a plurality of times in a short period of time (so-called idling stop vehicle), fluctuations in the engine load and engine speed of the internal combustion engine 101 are large, and the storage catalyst is based on these values. If the particulate deposition amount 117 is estimated, an error is likely to occur in the estimation of the particulate deposition amount.
Therefore, the exhaust purifying device 116 estimates the particulate accumulation amount from the elapsed time Te after the engine start of the internal combustion engine 101 or the elapsed time Tr after the regeneration stop of the regeneration control by the forced regeneration means 119, and saturates the storage catalyst 117. Since the state is determined, no error occurs in the estimation of the amount of accumulated particulates, the saturated state of the storage catalyst 117 can be accurately determined, and the regeneration control can be executed reliably.

  This invention is capable of preventing emission of harmful substances even when the storage catalyst is in an inactive state at low temperatures for a long period of time, and not only internal combustion engines such as gasoline engines and diesel engines, but also combustion such as boilers and incinerators. It can also be applied to the exhaust treatment of equipment.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Combustion chamber 3 Intake device 4 Exhaust device 8 Fuel injection device 9 Fuel injection valve 10 Control device 11 Fuel injection amount calculation means 12 Outside temperature sensor 13 Atmospheric pressure sensor 14 Intake amount sensor 15 Crank angle sensor 16 Exhaust purification device 17 Storage catalyst 18 Adsorption amount estimation means 19 Regeneration control means 20 Catalyst temperature sensor 21 Forced regeneration means 22 Timing means 23 Engine start timer 24 Regeneration stop timer 25 Saturation adsorption time calculation means 26 Storage means

Claims (2)

  An occlusion catalyst for adsorbing harmful substances provided in an exhaust system of an internal combustion engine, an adsorption amount estimation means for estimating the amount of harmful substances adsorbed on the occlusion catalyst, and adsorption of harmful substances estimated by the adsorption amount estimation means And a regeneration control means for performing regeneration control for removing harmful substances from the storage catalyst based on the amount, wherein the exhaust purification device detects an active state of the storage catalyst. And an inactive state of the storage catalyst is detected by the active state detection means, and when it is determined that the storage catalyst is saturated based on the adsorption amount of the harmful substance estimated by the adsorption amount estimation means, An exhaust emission control device for an internal combustion engine, comprising: forced regeneration means for executing regeneration control.   The exhaust purification device includes a time measuring unit that measures an elapsed time from the start of the internal combustion engine or an elapsed time from the stop of the regeneration control, and the forced regeneration unit includes an elapsed time measured by the time measuring unit. 2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the storage catalyst is determined to be in a saturated state when a set value or more is reached.

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