JP4424159B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas purifying apparatus including a particulate filter that collects particulates contained in exhaust gas of an internal combustion engine.

  In recent years, the environmental impact of particulates (particulate matter, PM) discharged from diesel engines has become a major problem. Conventionally, a diesel particulate filter (hereinafter referred to as DPF) made of a ceramic porous body is known as a countermeasure, and is installed in the middle of the exhaust pipe to collect the particulates in the porous partition wall of the DPF. To be done. The DPF is regenerated by periodically burning and removing the collected particulates.

  The regeneration of the DPF is generally calculated based on the integrated value of the PM emission amount obtained based on the operating state, or the particulate accumulation amount calculated based on the differential pressure across the DPF (hereinafter referred to as PM accumulation amount). Is performed when the amount exceeds a predetermined amount, for example, post injection is performed to raise the DPF to a temperature higher than the temperature at which the particulates burn. However, depending on the operating conditions of the engine, the exhaust temperature may become a high temperature at which particulates can spontaneously burn, and in order to efficiently regenerate the DPF, the temperature raising means may be operated according to the operating conditions. desirable.

As a conventional technique, Patent Document 1 proposes a method of regenerating a DPF by selecting different temperature raising means according to the operating state of the engine when the PM accumulation amount reaches a predetermined value. The operating state (load state) of the engine can be divided into a plurality of regions depending on, for example, the engine speed and the output torque. Different regeneration operations are performed for each region, or the temperature rises in a region where natural combustion is possible. By not performing the operation, it is possible to regenerate the DPF while suppressing an increase in fuel consumption.
JP 2000-170521 A

  By the way, in the method of Patent Document 1, the regeneration operation is not performed in the low rotation and low load region when the amount of PM deposition that needs to be regenerated is exceeded. Stop playback operation. This is because it is difficult to raise the DPF up to the particulate combustion temperature in the low rotation and low load region, and is a result of giving priority to the improvement of fuel consumption. In this state, if engine low speed and low load operation such as idling or traffic congestion is performed for a long time, a large amount of particulates exceeding the allowable value will accumulate on the DPF, resulting in excessive temperature rise during regeneration. Cheap.

  On the other hand, it is considered to combine an intake throttle when raising the DPF temperature. If the intake air amount is reduced by reducing the valve opening of the intake throttle valve provided in the engine intake passage, the engine combustion state can be changed and the exhaust temperature can be raised. The DPF regeneration can be performed by combining the temperature raising means and the intake throttle.

  However, the above effect cannot be obtained if the intake throttle valve cannot be operated due to some problem with the intake throttle valve. Normally, since the intake throttle valve is fully opened when the power is turned off, the temperature cannot be raised to the activation temperature of the oxidation catalyst in the low engine speed and low load operation region, and it may be difficult to perform regeneration.

  In particular, in the engine low-speed and low-load operation region, the same problem as in Patent Document 1 occurs, and regeneration cannot be performed, so that the PM accumulation amount exceeds the specified amount. For this reason, when the regeneration by the temperature raising means becomes possible due to the change of the operation region, the DPF temperature at the time of regeneration is excessively increased, and the DPF may be damaged or the catalyst may be deteriorated.

  The present invention has been made in view of the above circumstances, and its purpose is to prevent the accumulation of a large amount of particulates exceeding the allowable amount on the DPF, and the deterioration of the DPF and the catalyst due to excessive temperature rise during regeneration. -To prevent damage and improve the safety and durability of the exhaust purification system.

In order to solve the above problems, an exhaust emission control device for an internal combustion engine according to claim 1 is provided with a plurality of temperature raising means for raising the temperature of a particulate filter that is installed in an exhaust passage and collects particulates in exhaust gas. As one, intake throttle means is provided in the intake passage of the internal combustion engine. Further, by detecting the particulate amount deposited on the particulate filter, the particulate amount, the PM deposition amount determining means for determining whether reaches the reference value for starting regeneration of the particulate filter, the internal combustion engine Regeneration control means for operating the plurality of temperature raising means is provided based on the determination result of the operation area determination means for determining which of the plurality of operation areas is set in advance. The PM accumulation amount determination means is a reference for changing the reference value for starting regeneration of the particulate filter from the normal reference value M1 to a smaller reference value M2 when an abnormality of the intake throttle means is detected. It has value changing means.

  The PM accumulation amount determining means normally performs regeneration determination when the particulate accumulation amount becomes equal to or greater than the reference value M1, and the regeneration control means regenerates the particulate filter by performing a temperature raising operation according to the operation state. When an abnormality in the intake throttle means is detected, the particulate amount serving as a reference for regeneration determination is switched to the reference value M2, and the regeneration determination is performed with a particulate amount smaller than the reference value M1.

  In this way, by determining regeneration early when the amount of particulate accumulation is relatively small, even if regeneration using the intake throttle means is difficult, it is possible to wait before the particulate amount exceeds the allowable amount. Time can be set. During this grace period, there is a possibility of changing to operating conditions suitable for regeneration of the particulate filter. It is possible to increase the probability that regeneration using a temperature raising means other than the above can be performed, and to increase the probability that the particulates can be safely removed by combustion. Therefore, the probability that the particulate filter is damaged or the catalyst is deteriorated due to excessive temperature rise can be suppressed, and the safety and durability of the exhaust emission control device can be improved.

  3. The exhaust emission control device according to claim 2, wherein the regeneration control means operates one or more temperature raising means selected in advance from a plurality of temperature raising means according to the operation region determined by the operation region determining means. As a result, the temperature of the particulate filter is raised above the combustion temperature of the particulates.

  Specifically, in the operation range where the exhaust temperature is relatively high and easily raised, a temperature raising means that prioritizes suppression of fuel consumption deterioration is selected, and in the operation region where the exhaust temperature is low, a plurality of temperature raising means are combined. Regeneration control can be performed efficiently by performing a temperature raising operation according to the operation region, such as quickly raising the temperature.

In the exhaust emission control device according to claim 3, when the operation region determined by the operation region determination unit when the abnormality of the intake throttle unit is detected is an operation region in which the temperature raising operation by the intake throttle unit is performed, Regeneration stop means for stopping all the temperature raising operations including the intake throttle means by the regeneration control means is provided.

  When the intake throttling means is abnormal, the temperature raising operation including the intake throttling means is not carried out, and the regeneration is stopped until the operating range in which other temperature raising means is adopted. It is possible to suppress the deterioration of fuel consumption due to simple operation.

5. The exhaust gas purifying apparatus according to claim 4, wherein when the particulate filter is a particulate filter with a catalyst having a catalyst supported on the surface, the regeneration control means operates in such a manner that the exhaust temperature is equal to or lower than the activation temperature of the catalyst in a plurality of operation regions. in the region, raised when an abnormality of the intake throttle means is not detected, an intake throttle means, a combination of at least one bets is selected from a plurality of Atsushi Nobori means, the particulate filter above the activation temperature of the catalyst After performing the catalyst temperature raising operation, the regeneration operation for raising the temperature of the particulate filter to the particulate combustion temperature or higher is performed using at least one selected from a plurality of temperature raising means.

  To regenerate a particulate filter with a catalyst, it is necessary to first activate the catalyst by raising the temperature. By selecting the most suitable temperature raising means for the catalyst temperature raising and the subsequent regeneration operation, it is more effective. Playback control can be realized. In particular, in the low-rotation and low-load operation region, the catalyst can be heated to an activation temperature or higher by combining the intake throttle means with other temperature raising means, and it is possible to regenerate the particulate filter, which was difficult in the past. It becomes. Therefore, even if the low-rotation and low-load operation continues for a long time, since the regeneration cannot be performed, the particulate accumulation amount does not exceed the allowable range, and safety and reliability can be improved.

  According to a fifth aspect of the present invention, there is provided an exhaust purification device comprising temperature detection means for detecting the exhaust temperature in the exhaust passage upstream of the particulate filter, and the operation region determination means is based on the exhaust temperature detected by the temperature detection means. Shall be determined.

  Specifically, the operating state is detected based on the exhaust temperature upstream of the particulate filter that well reflects the operating state of the internal combustion engine, and it is possible to easily determine which operating region is set in advance.

  7. The exhaust gas purification apparatus according to claim 6, wherein the regeneration control means uses a plurality of temperature raising means when the operation area determined by the operation area determination means is an operation area where the exhaust gas temperature is equal to or higher than the combustion temperature of the particulate filter. Do not perform the temperature raising operation.

  When it is determined that the particulate filter needs to be regenerated, if the exhaust gas temperature is high, the temperature riser is not operated, and natural regeneration is used to reduce fuel consumption due to unnecessary temperature rise operations. Can be prevented.

  The exhaust emission control device of claim 7 includes at least timing retard and post injection as the plurality of temperature raising means.

  Specifically, in a high-speed and high-load operation region where the exhaust temperature rises to about 500 ° C., the temperature can be easily raised to the particulate combustion temperature by, for example, timing retard. In the operation region where the exhaust temperature is lower than 500 ° C., regeneration can be performed quickly by giving priority to the temperature raising efficiency and using, for example, post injection. By appropriately combining these temperature raising means including the intake throttle means, optimum regeneration control can be performed in the entire operation region of the internal combustion engine.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings. FIG. 1 shows an overall configuration of an exhaust gas purification apparatus for an internal combustion engine. In this embodiment, the exhaust gas purifying apparatus is applied to a four-cylinder diesel engine 1. Each cylinder of the engine 1 is provided with an injector 11 so that fuel accumulated in the common rail 3 is injected into the combustion chamber. The fuel in the fuel tank 4 is pressurized by the pump 31 through the metering valve 41 and supplied to the common rail 3. The common rail 3 is provided with a pressure sensor 5 that detects the pressure of the common rail 3 and outputs it to the ECU 2.

  In the exhaust passage 12 of the engine 1, a diesel particulate filter (hereinafter referred to as an oxidation catalyst-attached DPF) 6 carrying an oxidation catalyst on its surface is installed. The oxidation catalyst-attached DPF 6 is formed, for example, by forming heat-resistant ceramics such as cordierite into a honeycomb structure, and sealing a number of cells serving as gas flow paths so that the inlet side or the outlet side are staggered. An oxidation catalyst such as Pt is applied to the wall surface. The exhaust gas discharged from the engine 1 flows downstream while passing through the porous partition wall of the oxidation catalyst-attached DPF 6, and particulates are collected and gradually accumulated therebetween. In the present embodiment, an oxidation catalyst is supported in order to lower the regeneration temperature by using a catalytic reaction and perform stable combustion. However, a configuration having an oxidation catalyst upstream of the DPF is also possible.

  Temperature sensors 71 and 72 are installed in the exhaust passage 12 on the upstream side and the downstream side of the DPF 6 with an oxidation catalyst, respectively. The temperature sensors 71 and 72 are for detecting the temperature of the exhaust gas flowing through the exhaust passage 12, and detect the temperature of the gas entering or exiting the DPF 6 with the oxidation catalyst and outputting it to the ECU 2. The input gas temperature of the oxidation catalyst-attached DPF 6 detected by the temperature sensor 71 serving as a temperature detecting means is used for detecting the operating state of the engine 1 described later. Further, the outgas temperature of the oxidation catalyst-attached DPF 6 detected by the temperature sensor 72 is used to detect the temperature of the oxidation catalyst and the oxidation catalyst-attached DPF 6. It is difficult to directly measure the temperature of the oxidation catalyst and the DPF 6 with an oxidation catalyst (the temperature at the center), and the outgas temperature can usually be regarded as the temperature of the DPF 6 with an oxidation catalyst, but in order to increase the detection accuracy. In addition, the temperature of the oxidation catalyst-attached DPF 6 can be estimated in consideration of a time delay until the output gas temperature is reflected.

  In addition, a differential pressure sensor 8 is connected to the exhaust passage 12 in order to know the amount of particulates (PM accumulation amount) collected and accumulated in the DPF 6 with oxidation catalyst. Connected to both ends of the differential pressure sensor 8 are pressure introducing passages 81 and 82 communicating with the upstream and downstream exhaust passages 12 of the DPF 6 with an oxidation catalyst, respectively. A signal corresponding to the differential pressure is output to the ECU 2.

  An intake throttle valve 14 serving as an intake throttle means is installed in the intake passage 13 of the engine 1. The intake throttle valve 14 has a known configuration and is fully opened when not energized. The valve opening degree of the intake throttle valve 14 can be changed by a command from the ECU 2, and the flow passage cross-sectional area of the intake passage 13 is changed accordingly, and the intake air amount can be adjusted. As will be described in detail later, in the present invention, the intake throttle operation by the intake throttle valve 14 is one of the temperature raising means of the DPF 6 with an oxidation catalyst. As the temperature raising means, in addition to the intake throttle, post injection, timing retard (fuel injection timing delay) or the like can be mentioned. Either one of these temperature raising means is adopted, or two or more means are used. Can be combined.

  Further, various sensors such as an accelerator opening sensor, a rotation speed sensor, and a fuel level sensor (not shown) are connected to the ECU 2. The ECU 2 calculates the optimum fuel injection amount, injection timing, injection pressure, etc. according to the operating state based on the detection signals from these sensors, and controls the metering valve 41 so that the common rail 3 has a predetermined injection pressure. The high pressure fuel is pumped to the common rail 3 and the injector 11 is driven at a predetermined timing to control the fuel injection to the engine 1.

  In addition, the ECU 2 controls the regeneration of the oxidation catalyst-attached DPF 6, and in order to incinerate and remove the accumulated particulates when the PM accumulation amount reaches a specified value, the temperature of the oxidation catalyst-attached DPF 6 reaches a temperature at which the particulates can burn. Raise. For this reason, the ECU 2 in the present embodiment calculates the PM accumulation amount on the oxidation catalyst-attached DPF 6 based on the detection result of the differential pressure sensor 8, and the calculated PM accumulation amount starts regeneration of the oxidation catalyst-attached DPF 6. It is determined whether or not the reference value has been reached (PM accumulation amount determination means), and it is determined to which of a plurality of preset operation regions the operation state of the engine 1 known from the exhaust temperature or the like corresponds (operation region) Determination means). Then, based on the determination results of the PM accumulation amount determination means and the operation region determination means, the plurality of temperature raising means described above are operated to regenerate the oxidation catalyst-attached DPF 6 (regeneration control means).

  Specifically, when the PM accumulation amount reaches the reference value, the temperature raising means that is optimal for the operation state of the engine 1 at that time is selected based on the determined operation region, and the oxidation catalyst is attached. The temperature raising operation of the DPF 6 is performed. FIG. 2 shows the relationship between the operating state of the engine 1 (in this case, the engine speed and torque) and the exhaust temperature, and the exhaust temperature becomes higher in the region where the engine speed and torque values are larger, while the engine speed. The exhaust temperature is lower in the region where the torque value is smaller. In this embodiment, the engine 1 is operated in five regions from a high-speed and high-load region A having a high exhaust temperature (for example, 550 ° C. or higher) to a low-speed and low-load region E having a low exhaust temperature (for example, less than 250 ° C.). Shall be divided into The region A and the region E are divided into three regions, a region B (for example, 500 ° C. or higher), a region C (for example, 350 ° C. or higher), and a region D (for example, 250 ° C. or higher) based on the exhaust temperature. .

Next, the temperature raising means and the temperature raising operation employed in each region will be described.
(1) In the region A, the exhaust temperature becomes a high temperature of 550 ° C. or higher, so the particulates deposited on the oxidation catalyst-attached DPF 6 can spontaneously burn. Therefore, in region A, DPF natural regeneration is performed without operating the temperature raising means.
(2) In region B, timing retard is performed as a temperature raising means. In this region, since the exhaust temperature is relatively high at 500 ° C. or higher, the timing of retarding the fuel injection timing makes it possible to raise the temperature of the DPF 6 with oxidation catalyst to 550 ° C. or higher by setting the exhaust gas to a higher temperature than usual. As a result, while suppressing increase in fuel consumption, it is possible to regenerate the DPF 6 with oxidation catalyst by burning and removing the particulates.
(3) In region C, DPF regeneration by post injection is performed as a temperature raising means. In this region, since the exhaust temperature is not sufficiently high at 350 ° C. or more, after performing the main injection from the injector 11, post injection for injecting a small amount of fuel is performed, HC is supplied into the exhaust, and catalytic combustion is performed. The DPF 6 with an oxidation catalyst can be regenerated by increasing the temperature of the DPF 6 with an oxidation catalyst to 550 ° C. or higher with the combustion heat of HC and burning the particulates.
(4) In region D, after performing the temperature raising operation of the oxidation catalyst by timing retard as the temperature raising means, the DPF regeneration operation by post injection is performed. In this region, the exhaust temperature is somewhat low at 250 ° C. or higher, so that the oxidation catalyst is not sufficiently activated, and fuel efficiency tends to be deteriorated by DPF regeneration using only post injection. Therefore, first, the timing retard is performed to raise the temperature to the temperature at which the oxidation catalyst is activated (for example, 350 ° C.), and then the post-injection is performed to raise the temperature of the DPF 6 with the oxidation catalyst to 550 ° C. or higher and regenerate. To do. By performing the temperature raising operation in two strokes in this way, the supplied HC can be burned efficiently and fuel consumption deterioration can be suppressed.
(5) In region E, the catalyst temperature is raised by timing retard and intake air throttle as the temperature raising means, and then DPF regeneration by post injection is performed. This region is a region where the exhaust temperature is lower than that of region D and less than 250 ° C., so it has been difficult to raise the temperature of the catalyst in the past, and DPF regeneration has not been performed with priority on fuel efficiency. In the embodiment, by combining an intake throttle as a temperature raising means, heat dissipation to the exhaust is suppressed and the temperature is easily increased. As a result, the temperature can be raised to the activation temperature of the oxidation catalyst (for example, 350 ° C.) or higher, and then the post-injection is performed to efficiently burn the supplied HC, and the temperature of the oxidation catalyst-attached DPF 6 is set to 550 ° C. or higher. Can be heated and regenerated.

  The temperature raising means selected in each region is shown as an example and is not limited to this. For example, in the present embodiment, the intake throttle operation is performed to raise the temperature of the oxidation catalyst in the region E, but the intake throttle operation can be combined in other regions. In this embodiment, the operation region is divided into five regions, but the number of regions and the exhaust temperature that is the boundary value of each region can also be changed according to, for example, the type of catalyst, the presence or absence of catalyst loading, and other conditions. It is.

Here, the PM deposition amount determination means, which is a characteristic part of the present invention, will be described.
In the operation region (region E in FIG. 2) where the intake throttle is selected as the temperature raising means, if the intake throttle valve 14 malfunctions and the intake throttle operation cannot be performed, the regeneration control cannot be performed normally (region). E makes it difficult to raise the temperature of the catalyst). Further, if the state of the region E is maintained for a long time, the particulates may be accumulated beyond the allowable value, and there is a risk of burning at once due to a change in the operating state thereafter. Therefore, in the present invention, a plurality of reference values for determining whether or not DPF regeneration is necessary in the PM accumulation amount determination means are provided. That is, the PM accumulation amount at which DPF regeneration is started at the normal time is set as the reference value M1, and when any abnormality is detected in the intake throttle valve 14, the PM accumulation amount at which DPF regeneration is started is a reference value smaller than the reference value M1 at the normal time. The setting is changed to M2 (reference value changing means) to avoid the regeneration temperature from exceeding the allowable limit of the base material and catalyst of the DPF 6 with oxidation catalyst. The smaller the reference value M2, the higher the safety, but the higher the reproduction frequency. Therefore, it is preferable to set the reference value M2 large within a range in which safety can be ensured. Specifically, the ratio of the reference value M2 to the normal reference value M1 may be about 1: 0.8.

  When the PM deposition amount reaches the reference value M2 and the PM deposition amount determination unit performs regeneration determination, the regeneration control unit determines the operation region based on FIG. 2 and performs a temperature raising operation set for each region to oxidize the regeneration region. Regenerate the DPF 6 with catalyst. However, when the determination result of the operation region determining means is the region E where the intake throttle is used as the temperature raising means, the catalyst temperature rise is not normal due to the abnormality of the intake throttle valve 14, and regeneration is difficult. The temperature raising operation by the control means is stopped (regeneration stop means). Also in this case, there is a sufficient grace time until the PM accumulation amount that may actually overheat after reaching the regeneration determination, and when the operation region other than the region E is reached, another temperature increase Since the regeneration control by the means is started, the particulates deposited on the oxidation catalyst-attached DPF 6 can be safely burned.

  Next, a control routine for regeneration of the DPF 6 with the oxidation catalyst by the ECU 2 will be described with reference to flowcharts shown in FIGS. FIG. 3 shows the basic operation of the DPF regeneration control, and this routine is executed in the ECU 2 at a predetermined cycle. Step 100 corresponds to the PM accumulation amount determination means, step 200 corresponds to the operation region determination means, and step 300 corresponds to the regeneration control means, and these details are shown in FIGS. 4, 5, and 6 to 10, respectively. In the PM accumulation amount determination of FIG. 4, first, in step 101, it is determined whether or not the intake throttle valve 14 is normal. If it is determined normal, the routine proceeds to step 102 where the PM accumulation amount on the DPF 6 with oxidation catalyst is determined. It is compared with the reference value M1 at the normal time. If it is determined that it is not normal, the routine proceeds to step 103, where the PM deposition amount on the oxidation catalyst-attached DPF 6 is compared with a reference value M2 smaller than the reference value M1.

  The failure determination of the intake throttle valve 14 in step 101 is performed in another routine. For example, a control signal from the ECU 2 to the intake throttle valve 14 is compared with a detection signal of an intake air amount sensor (not shown), and the deviation is within an allowable range. When exceeded, it can be determined as a failure. The amount of PM deposited on the DPF 6 with an oxidation catalyst in Steps 102 and 103 can be calculated based on the differential pressure before and after the DPF 6 with an oxidation catalyst detected by the differential pressure sensor 8. This utilizes the fact that the differential pressure generated when a predetermined amount of exhaust gas passes through the oxidation catalyst-attached DPF 6 has a correlation with the amount of particulates deposited on the oxidation catalyst-attached DPF 6, and these relations are experimentally determined in advance. The obtained map data is stored in the memory of the ECU 2.

  In steps 102 and 103, when it is determined that the PM accumulation amount is the reference value M1 or the reference value M2 or more, the operation region determination is performed according to FIG. If the determination in steps 102 and 103 is negative, it is determined that regeneration is not yet necessary, and the present control routine is temporarily terminated.

  In the operation region determination of FIG. 5, it is determined which region from the region A to the region E the operation state of the engine 1 corresponds to from the exhaust temperature. As the exhaust gas temperature, the inlet gas temperature of the DPF 6 with oxidation catalyst detected by the temperature sensor 71 is used. In step 201, it is determined whether the detected exhaust gas temperature is equal to or higher than T1 (here, 550 ° C.). If the exhaust temperature is equal to or higher than T1 (here, 550 ° C.), the region A is determined. Thereafter, the process proceeds to the regeneration control process of FIG. 6, but in the region A where the exhaust gas temperature is high, the particulates can be spontaneously combusted as described above, and thus no special temperature raising operation is performed.

  If the exhaust temperature is lower than T1 in step 201, it is determined in step 202 whether the exhaust temperature is equal to or higher than T2 (here, 500 ° C.). If the exhaust temperature is equal to or higher than T2, the region B is determined, and the process proceeds to the regeneration control process of FIG. In step 301 in FIG. 7, a timing retard that delays the fuel injection timing is performed, and in step 302, it is determined whether or not the regeneration process is to be ended. The determination of the end of reproduction can be made, for example, based on whether or not timing retard is performed for a predetermined time, and steps 301 and 302 are repeated until it is determined that the reproduction is completed. Alternatively, the regeneration is determined to be complete depending on whether or not the temperature of the DPF 6 with an oxidation catalyst detected or estimated from the temperature of the outgassing of the DPF 6 with an oxidation catalyst detected by the temperature sensor 72 has reached a predetermined temperature (here, 550 ° C.). You can also.

  If the exhaust temperature is lower than T2 in step 202, the routine proceeds to step 203, where it is determined whether the exhaust temperature is equal to or higher than T3 (here, 350 ° C.). If the exhaust gas temperature is equal to or higher than T3, it is determined as the region C, and the process proceeds to the regeneration control process of FIG. In step 311 of FIG. 8, post injection is performed, and in step 312, it is determined whether or not the regeneration process is to be ended. This reproduction end determination is performed in the same manner as in step 302 of FIG. 7, and steps 311 and 312 are repeated until it is determined that reproduction ends.

  When the exhaust temperature is lower than T3 in step 203, the routine proceeds to step 204, where it is determined whether or not the exhaust temperature is equal to or higher than T4 (here, 250 ° C.). If the exhaust temperature is equal to or higher than T4, it is determined as the region D, and the process proceeds to the regeneration control process of FIG. In step 321 of FIG. 9, timing retard is performed, and in step 322, it is determined whether or not the temperature of the oxidation catalyst supported on the DPF 6 with oxidation catalyst is 350 ° C. or higher. The catalyst temperature can be detected or estimated from, for example, the temperature sensor 72 downstream of the DPF 6 with oxidation catalyst, and steps 321 and 322 are repeated until the catalyst temperature is determined to be 350 ° C. or higher. If an affirmative determination is made in step 322, post injection is performed in step 323, and it is determined in step 324 whether or not the regeneration process is to be terminated. The determination of the end of reproduction is performed in the same manner as in step 302 of FIG. 7, and steps 323 and 324 are repeated until it is determined that the reproduction is completed.

  If the exhaust temperature is lower than T4 in step 204, the process proceeds to step 205. In step 205, it is determined whether or not the intake throttle valve 14 is normal. If the intake throttle valve 14 is not normal, it is determined that regeneration control is impossible, and the present control routine is temporarily terminated. If the intake throttle valve 14 is normal, it is determined as the region E, and the process proceeds to the regeneration control process of FIG. In step 331 of FIG. 10, in addition to the timing retard, intake throttle is performed to reduce the intake amount by reducing the valve opening of the intake throttle valve 14, and in step 332, it is determined whether the catalyst temperature is 350 ° C. or higher. To do. The determination of the catalyst temperature is performed in the same manner as in step 322 in FIG. 9, and steps 331 and 332 are repeated until it is determined that the catalyst temperature is 350 ° C. or higher. If an affirmative determination is made in step 332, post injection is performed in step 333, and it is determined in step 334 whether or not the regeneration process is to be terminated. This reproduction end determination is performed in the same manner as step 302 in FIG. 7, and steps 333 and 334 are repeated until it is determined that reproduction ends.

  As described above, in the present invention, when the intake throttle valve 14 fails, the PM accumulation amount for determining DPF regeneration is switched from the normal reference value M1 to the smaller reference value M2, so that the regeneration mode using the intake throttle is used. Even in the case where the system does not operate normally, the DPF can be safely regenerated by another regeneration mode before the PM accumulation amount exceeds the allowable amount, and the durability is improved. In addition, by performing a temperature raising operation using an appropriate temperature raising means according to the operation region during regeneration, it is possible to suppress deterioration in fuel consumption to a minimum, and to provide an exhaust purification device that is excellent in safety and reliability. realizable.

1 is an overall schematic configuration diagram of an exhaust gas purification apparatus for an internal combustion engine according to a first embodiment of the present invention. FIG. 5 is a diagram in which an engine operating region is divided into a plurality of regions according to exhaust gas temperature in a diagram in which engine speed and torque are both axes. It is a flowchart figure which shows the action | operation of ECU by this invention. It is a flowchart figure of PM deposition amount determination processing. It is a flowchart figure of a driving | running | working area | region determination process. FIG. 5 is a flowchart of regeneration control processing in an engine operation area A. 6 is a flowchart of regeneration control processing in an engine operation region B. FIG. 5 is a flowchart of regeneration control processing in an engine operation region C. FIG. 5 is a flowchart of regeneration control processing in an engine operation region D. FIG. 6 is a flowchart of regeneration control processing in an engine operation region E. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 11 Injector 12 Exhaust passage 13 Intake passage 14 Intake throttle valve (intake throttling means)
2 ECU (PM accumulation amount determination means, operation region determination means, regeneration stop means, regeneration control means)
3 Common rail 31 Pump 4 Fuel tank 41 Metering valve 5 Pressure sensor 6 DPF with oxidation catalyst (Particulate filter)
71 Temperature sensor (temperature detection means)
72 Temperature sensor 8 Differential pressure sensor 81, 82 Pressure introduction path

Claims (7)

A particulate filter installed in the exhaust passage of the internal combustion engine and collecting particulates in the exhaust;
A plurality of temperature raising means for raising the temperature of the particulate filter;
By detecting the particulate amount deposited on the particulate filter, the particulate amount, the PM deposition amount determining means for determining whether reaches the reference value for starting reproduction of the particulate filter,
Driving region determination means for determining which of a plurality of predetermined driving regions the operating state of the internal combustion engine corresponds to;
In an exhaust gas purification apparatus for an internal combustion engine comprising a regeneration control means for operating the plurality of temperature raising means based on the judgment results of the PM accumulation amount judgment means and the operation region judgment means,
As one of the plurality of temperature raising means, an intake throttle means is provided in the intake passage of the internal combustion engine,
The PM accumulation amount determining means is configured to change the reference value for starting regeneration of the particulate filter to a reference value M2 smaller than the normal reference value M1 when an abnormality of the intake throttle means is detected. An exhaust purification device for an internal combustion engine, characterized by comprising a changing means.   The regeneration control means operates the one or more temperature raising means selected in advance from the plurality of temperature raising means in accordance with the operation area determined by the operation area determination means, whereby the particulates The exhaust emission control device for an internal combustion engine according to claim 1, wherein the temperature of the filter is raised to a temperature equal to or higher than the combustion temperature of the particulates. When the abnormality of the intake throttle means is detected, the operating region is determined in the operating region determining means, when it is operating range to carry out heating operation by the intake throttle means, said by the reproduction control means 3. An exhaust emission control device for an internal combustion engine according to claim 1 , further comprising a regeneration stop means for stopping all the temperature raising operations including the intake throttle means . The particulate filter has a catalyst supported on the surface,
The regeneration control means includes the intake throttle means and the plurality of risers when an abnormality of the intake throttle means is not detected in an operation area where the exhaust temperature is equal to or lower than the activation temperature of the catalyst among the plurality of operation areas. by combining at least one bets selected from raising means, after the particulate filter implemented catalyst Atsushi Nobori operation for raising the temperature above the activation temperature of the catalyst, at least one selected from the plurality of Atsushi Nobori means The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein a regeneration operation for raising the temperature of the particulate filter to a temperature equal to or higher than the combustion temperature of the particulates is performed using A temperature detecting means for detecting the exhaust temperature is provided in the exhaust passage upstream of the particulate filter;
The exhaust purification device for an internal combustion engine according to any one of claims 1 to 4, wherein the operating region determining means determines the operating region based on the exhaust temperature detected by the temperature detecting means.   The regeneration control means does not perform the temperature raising operation by the plurality of temperature raising means when the operation area determined by the operation area determination means is an operation area where the exhaust gas temperature is equal to or higher than the combustion temperature of the particulate filter. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 5.   The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 6, comprising at least timing retard and post injection as the plurality of temperature raising means.

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