JP6894249B2 - Exhaust purification device - Google Patents

Description

The present invention relates to an exhaust gas purification device for purifying particulate matter contained in exhaust gas discharged from an internal combustion engine, and in particular, makes it possible to suppress the accumulation of non-combustible substances.

An internal combustion engine that incorporates an exhaust purification device in the exhaust passage that captures or adsorbs harmful components contained in the exhaust or detoxifies it in order to minimize the impact on the environment of the exhaust emitted from the internal combustion engine is known. Has been done. For example, in the internal combustion engine of the compression ignition type, because it contains combustible particulate material containing carbonaceous or hydrocarbon component called a PM (P articulate M atter) in the exhaust gas, the PM trapped in the exhaust passage I am trying to capture this by incorporating it. In addition, the engine oil that enters the combustion chamber of the internal combustion engine as the piston reciprocates contains so-called ash such as calcium compounds, that is, ash, as well as metal-based substances containing manganese compounds, zinc compounds, phosphorus, sulfur, and the like. The agent is mixed. Since these metal compounds are usually burned in the combustion chamber and discharged from the combustion chamber to the exhaust passage as non-combustible components together with the exhaust without being completely decomposed, such non-combustible components are also captured in the PM trap together with PM. Will be done.

In this way, if PM and non-combustible components contained in the exhaust gas continue to accumulate in the PM trap, the PM trap will be clogged, making it difficult to continuously and smoothly operate the internal combustion engine. Therefore, it is necessary to burn the PM captured in the PM trap or remove the non-combustible component from the PM trap to regenerate the PM trap on a regular basis.

Is what is best known as a PM trap described above is catalyzed DPF (Diesel P articulate F ilter) , it can be removed by burning PM deposited by passing the hot exhaust. However, it is difficult to remove the non-combustible component from the catalyzed DPF simply by passing it through a high-temperature exhaust gas. In order to deal with such a problem, in Patent Document 1, the exhaust gas flowing into the catalytic DPF is set to a rich air-fuel ratio state in the operating state of the internal combustion engine in which the exhaust gas flow rate flowing through the exhaust passage is small. As a result, the calcium compound which occupies most of the metal compound component, particularly the non-combustible component is reduced, and as a result, the calcium compound can be removed from the catalytic DPF.

Japanese Unexamined Patent Publication No. 10-054268

Normally, when the filter is regenerated, the filter is heated to 600 ° C. or higher to burn the flammable particulate matter trapped in the filter. However, the non-combustible component captured by the filter does not peel off from the filter even when the filter is heated to 600 ° C. or higher, and remains on the filter. Regarding the above-mentioned catalytic DPF, as a practical matter, not only the metal compound component but also PM is deposited on the catalytic DPF, and even if the calcium compound described in Patent Document 1 can be reduced in such a situation, it remains. It is difficult to discharge the non-combustible component of the above from the catalyzed DPF.

An object of the present invention is to provide an exhaust gas purification device capable of efficiently exfoliating non-combustible components trapped in a filter together with flammable particulate matter from the filter.

When the flammable particulate matter trapped in the filter is burned by heating it to about 500 to 550 ° C. when the filter is regenerated, the present inventors peel off the non-combustible component trapped in the filter from the filter. We found that it could be excluded from the filter.

The exhaust gas purification device according to the present invention was made in view of such findings, and is provided with a filter that is arranged in the exhaust passage of an internal combustion engine and captures combustible particulate matter contained in the exhaust gas flowing through the exhaust passage. , A means for obtaining the accumulated amount of the particulate matter captured by the filter, a combustion means for burning the particulate matter captured by the filter, and a means for obtaining the accumulated amount of the non-combustible component captured by the filter. And a control means for controlling the operation of the combustion means. When the deposited amount of the particulate matter captured by the filter is equal to or more than the first predetermined value and the deposited amount of the non-combustible component captured by the filter is less than the second predetermined value, the control means of the filter. The operation of the combustion means is controlled so that the temperature becomes the first temperature. On the other hand, when the accumulated amount of the particulate matter captured by the filter is equal to or greater than the first predetermined value and the accumulated amount of the non-combustible component captured by the filter is equal to or greater than the second predetermined value, the control The means controls the operation of the combustion means so that the temperature of the filter becomes a second temperature lower than the first temperature.

In the present invention, when the accumulated amount of the particulate matter captured by the filter is equal to or greater than the first predetermined value, the filter regeneration process for burning the particulate matter captured by the filter is performed. At this time, if the accumulated amount of the non-combustible component captured by the filter is less than the second predetermined value, the temperature of the filter is raised to the first temperature to burn the particulate matter captured by the filter. On the other hand, when the accumulated amount of the non-combustible component captured by the filter is equal to or higher than the second predetermined value, the temperature of the filter is raised to a second temperature lower than the first temperature, and the non-combustible component captured by the filter is raised. Is easily peeled off from the filter, and at the same time, the separated non-combustible component is allowed to flow to the downstream side of the filter by burning the particulate matter trapped in the filter.

In the exhaust gas purification device according to the present invention, it is effective that the first temperature is 600 ° C. or higher and the second temperature is in the range of 500 ° C. to 550 ° C.

The cumulative amount of heat input to the filter due to the second temperature may be acquired. When the cumulative amount of heat input exceeds the threshold value at which the non-combustible component starts to rise from the filter, the exhaust flow rate passing through the filter is increased by a predetermined time to promote the flow of the non-combustible component to the downstream side of the filter. Is effective. At this time, it is effective to interrupt the heating of the filter by the second temperature while increasing the exhaust flow rate passing through the filter. Further, as a means for increasing the exhaust flow rate passing through the filter, when the vehicle is in the EGR operating region, the opening degree of the EGR control valve is narrowed, or when the vehicle is not in the EGR operating region, it is exhausted from the outside by an air compressor. Compressed air can be supplied to the passage.

The filter may be a catalyzed DPF, in which case the oxidation catalyst may be distributed throughout the filter, including in the pores of the filter, via a carrier. Alternatively, the oxidation catalyst may be arranged only on the surface of the filter facing the upstream side of the exhaust passage via the carrier.

The average pore diameter of the filter is preferably 12 μm or more so that the non-combustible component peeled from the filter can pass through. However, the average pore size is preferably 16 μm or less in order to capture particulate matter.

When the second predetermined value is less than 10 μm, clogging of the filter by the non-combustible component does not substantially occur, so that the second predetermined value of the non-combustible component may be 10 μm.

The combustion means are arranged in an exhaust passage on the upstream side of the filter to supply fuel to this exhaust passage, and are arranged in an exhaust passage between the fuel addition valve and the filter, and are arranged in the fuel addition valve. It may include an oxidation catalyst device that burns the fuel added to the exhaust passage to raise the temperature of the exhaust gas flowing into the filter.

According to the exhaust gas purification device of the present invention, in addition to removing the particulate matter trapped in the filter from the filter, the non-combustible component trapped in the filter together with the particulate matter can be more reliably separated from the filter. As a result, the filter regeneration process can be efficiently performed.

When the second temperature is set in the range of 500 ° C. to 550 ° C., the non-combustible component captured by the filter can be more reliably separated from the filter.

When the oxidation catalyst is supported on the filter via a carrier, the combustion of the particulate matter can be further promoted.

When the average pore diameter of the filter is 16 μm or less, particulate matter can be reliably captured by the filter.

When the average pore diameter of the filter is 12 μm or more, the incombustible component exfoliated from the filter can be discharged from the filter to the exhaust passage on the downstream side thereof.

When the second predetermined value of the non-combustible component is set to 10 μm, the number of times the filter is heated at the second temperature can be reduced, and the filter regeneration process can be efficiently performed.

When the combustion means includes a fuel addition valve and an oxidation catalyst device, the temperature of the filter can be controlled more quickly and accurately.

It is a system conceptual diagram of one Embodiment which applied this invention to a compression ignition type internal combustion engine. It is a control block diagram of the main part in the embodiment shown in FIG. In the embodiment shown in FIG. 1, it is a map showing the relationship between the engine speed, the fuel injection amount, the EGR operating region, and the non-EGR operating region. It is a graph which shows typically the relationship between the exhaust temperature on the downstream side of a DPF and the temperature of a DPF. It is sectional drawing which extracted and enlarged the part of the DPF in the embodiment shown in FIG. It is an extraction enlarged sectional view schematically showing another embodiment of a filter. In the embodiment shown in FIG. 1, it is a graph showing the relationship between the heating time for the DPF, the heating temperature thereof, and the start of the floating of the incombustible component from the DPF and the time when the movement is completed. It is a graph which shows typically the relationship between the cumulative mileage of a vehicle, and the accumulation amount of a non-combustible component. It is a flowchart which shows the exhaust gas purification procedure in the embodiment shown in FIG.

An embodiment in which the exhaust gas purification device according to the present invention is incorporated into a compression ignition type internal combustion engine will be described in detail with reference to FIGS. 1 to 9. However, the present invention is not limited to such an embodiment, and the configuration can be appropriately changed according to the characteristics required for the target internal combustion engine.

The concept of the engine system in this embodiment is shown in FIG. 1, and the control block in this engine system is shown in FIG. In addition to the valve operating mechanism and silencer for intake and exhaust of the engine 10, some of the various sensors required for smooth operation of the engine 10 are omitted in FIG. 1 for convenience. Please note that it has been done.

The engine 10 in the present embodiment is a compression ignition type multi-cylinder internal combustion engine that spontaneously ignites by injecting light oil as fuel directly from a fuel injection valve 11 into a combustion chamber 10a in a compressed state. However, the present invention can be applied even to a single-cylinder internal combustion engine. The cylinder head 12 in which the intake port 12a and the exhaust port 12b facing the combustion chamber 10a are formed has a valve operating mechanism (not shown) including an intake valve 13a for opening and closing the intake port 12a and an exhaust valve 13b for opening and closing the exhaust port 12b. It has been incorporated. The fuel injection valve 11 mentioned above is also incorporated in the cylinder head 12.

The fuel injection valve 11 in the present embodiment is a direct injection single injection type that directly injects light oil as fuel into the combustion chamber 10a only immediately before the end of the compression stroke, that is, immediately before the compression top dead center of the piston 14a. , Not limited to this.

The injection amount and injection timing of the fuel supplied from the fuel injection valve 11 into the combustion chamber 10a are controlled by the ECU 16 based on the operating state of the vehicle including the amount of depression of the accelerator pedal 15 by the driver. The amount of depression of the accelerator pedal 15 is detected by the accelerator opening sensor 17, and the detection information is output to the ECU 16.

The ECU 16 in the present embodiment includes an operating state determination unit 16a for determining the operating state of the vehicle and the engine 10 based on information from the accelerator opening sensor 17 and various sensors described later, a fuel injection setting unit 16b, and fuel. It has an injection valve drive unit 16c.

The fuel injection setting unit 16b sets the drive torque of the engine 10, that is, the fuel injection amount from the fuel injection valve 11, and the injection timing thereof, based on the operating state of the vehicle determined by the operating state determination unit 16a. The fuel injection valve drive unit 16c of the ECU 16 drives the fuel injection valve 11 so that the fuel corresponding to the fuel injection amount set by the fuel injection setting unit 16b is injected at the set injection timing.

The intake pipe 18 which is connected to the cylinder head 12 so as to communicate with the intake port 12a and forms the intake passage 18a together with the intake port 12a has a throttle for adjusting the opening degree of the intake passage 18a via the throttle actuator 19. The valve 20 is incorporated. The opening degree of the throttle valve 20, that is, the throttle opening degree, is set by the throttle opening degree setting unit 16d of the ECU 16 based on the amount of depression of the accelerator pedal 15 detected by the accelerator opening degree sensor 17 and the operating state of the vehicle. .. Then, the throttle valve drive unit 16e of the ECU 16 drives the throttle valve 20 via the throttle actuator 19 so that the opening degree is set by the throttle opening degree setting unit 16d. The intake passage 18a on the upstream side of the throttle valve 20 is provided with an air flow meter 21 that detects the intake flow rate flowing therethrough and outputs these to the ECU 16.

A crank angle sensor 22 that detects the rotation phase of the crankshaft 14c to which the piston 14a is connected via the connecting rod 14b, that is, the crank angle and outputs the crank angle to the ECU 16 is attached to the cylinder block 14 in which the piston 14a reciprocates. Has been done. Based on the information from the crank angle sensor 22, the operating state determination unit 16a of the ECU 16 grasps the rotation phase of the crankshaft 14c, the engine rotation speed, and the traveling speed of the vehicle in real time.

The exhaust pipe 23 connected to the cylinder head 12 so as to communicate with the exhaust port 12b defines an exhaust passage 23a together with the exhaust port 12b. The engine system of the present embodiment includes an EGR device 24, an exhaust turbine type supercharger (hereinafter, simply referred to as a supercharger) 25, a fuel addition valve 26 for adding fuel to the exhaust passage 23a, and exhaust gas purification. The device 27 is further incorporated.

The EGR device 24 guides a part of the exhaust gas flowing in the exhaust passage 23a to the intake passage 18a, _{and suppresses the generation of NO X} , that is, nitrogen oxides contained in the exhaust. The EGR device 24 includes an EGR pipe 28 that defines the EGR passage 28a, and an EGR control valve 29 that is provided in the EGR pipe 28 and controls the flow rate of exhaust gas flowing through the EGR passage 28a. One end of the EGR pipe 28 communicates with the exhaust passage 23a between the cylinder head 12 and the turbine 25a of the turbocharger 25, and the other end communicates with the intake passage 18a between the throttle valve 20 and the cylinder head 12. There is.

The operating state determination unit 16a of the ECU 16 stores a map relating to the EGR operating region as shown in FIG. 3 which is preset based on the engine 10 rotation speed and the fuel injection amount from the fuel injection valve 11. In the present embodiment, when the operating state determination unit 16a of the ECU 16 determines that the vehicle equipped with the engine 10 is in the EGR operating region, the opening degree of the EGR control valve 29 is adjusted to the ECU 16 according to the operating state of the vehicle at this time. It is set by the EGR amount setting unit 16f of. The EGR control valve drive unit 16g of the ECU 16 controls the EGR control valve 29 to the opening degree set by the EGR amount setting unit 16f, and in other cases, basically closes the EGR passage 28a so as to block it. Drives the EGR control valve 29.

The supercharger 25 is for supercharging the combustion chamber 10a by utilizing the kinetic energy of the exhaust gas flowing through the exhaust passage 23a, increasing the intake density and increasing the intake flow rate. The main part of the turbocharger 25 is composed of a turbine 25a incorporated in the exhaust passage 23a and a compressor 25b that rotates integrally with the turbine 25a. The compressor 25b is incorporated in the intake passage 18a between the throttle valve 20 and the air flow meter 21. In the intake passage 18a between the compressor 25b of the supercharger 25 and the throttle valve 20, the intake air temperature heated via the compressor 25b due to heat transfer from the turbine 25a side exposed to high-temperature exhaust gas is lowered. An intercooler 25c is incorporated.

The exhaust purification device 27 for detoxifying harmful substances generated by the combustion of the air-fuel mixture in the combustion chamber 10a is arranged in the exhaust passage 23a on the downstream side of the turbine 25a of the turbocharger 25. Exhaust purification apparatus 27 of this embodiment, a DOC (D iesel O xidation C atalyst ) 30, has a catalyzed DPF 31, it is also possible to further add other catalytic converter, such as NO _X catalyst. The DOC 30 in the present embodiment is for performing a regeneration treatment of a catalytic DPF (hereinafter, simply referred to as DPF) 31 as a filter in the present invention arranged downstream thereof. That is, the fuel added to the exhaust passage 23a is burned from the fuel addition valve 26 arranged on the upstream side of the DOC 30, and the exhaust gas having a high temperature is sent to the DPF 31 to form flammable particles deposited on the DPF 31. It is possible to promote the combustion of a substance, that is, PM.

The temperature of the DPF 31 is detected by the filter temperature sensor 32 attached to the casing 27a of the exhaust gas purification device 27, and the information is output to the ECU 16.

Instead of such a filter temperature sensor 32, it is also possible to acquire the exhaust temperature flowing through the exhaust passage 23a on the downstream side of the DPF 31 and acquire the temperature of the DPF 31 based on this exhaust temperature. As shown in FIG. 4, which schematically shows the relationship between the exhaust temperature flowing through the exhaust passage 23a on the downstream side of the DPF 31 and the temperature of the DPF 31, the exhaust temperature flowing through the exhaust passage 23a on the downstream side of the DPF 31 is the temperature of the DPF 31. On the other hand, it has a correlation. Therefore, the temperature of the DPF 31 can be obtained almost accurately by detecting the exhaust temperature flowing through the exhaust passage 23a on the downstream side of the DPF 31 with an exhaust temperature sensor or the like.

FIG. 5 schematically shows a cross-sectional structure obtained by extracting and enlarging a portion of DPF31 in the present embodiment. The DPF 31 in the present embodiment is composed of a filter base material 31a having a honeycomb structure, a catalyst carrier layer 31b formed on the surface of the filter base material 31a, and an oxidation catalyst (not shown) supported on the catalyst carrier layer 31b. However, this is not limited. For example, FIG. 6 schematically shows the extracted enlarged cross-sectional structure of DPF31 similar to that in FIG. The DPF 31 includes a porous filter base material 31a, a second filter layer 31c, a catalyst carrier layer 31b laminated on the second filter layer 31c, and an oxidation catalyst (not shown) supported on the catalyst carrier layer 31b. It is composed of. The second filter layer 31c is formed on the surface of the filter base material 31a facing the upstream side of the exhaust passage 23a, and the average pore diameter thereof is set to 16 μm or less. Regardless of the configuration, the average pore diameter of the DPF 31 is preferably 12 μm or more and 16 μm or less in consideration of the ease of passing non-combustible components and the ease of capturing PM. The filter base material 31a is held in the casing 27a so as to partition the exhaust passage 23a.

When reproducing processing DPF 31 for removal of PM deposited trapped in the DPF 31, when heating the DPF 31 first temperature T _H of the hot, for example, 650 ° C., PM is vaporized by combustion, it is excluded from the DPF 31 However, the non-combustible component remains in DPF31. In contrast, when heating the DPF31 first temperature T is lower than the _H second temperature T _L, for example, 500-550 ° C., combustion vaporization of PM becomes gentle, to continue longer than normal playback time DPF31 Need arises. However, it has been found that the non-combustible component rises from the DPF 31 with the combustion of PM and easily flows to the downstream side of the DPF 31 along the exhaust flow. This behavior only occurs when more than the amount of accumulated PM is to some extent, be heated DPF 31 while accumulation amount is small in the PM to a second temperature T _L, incombustible components without raised from the DPF 31, DPF 31 Stays in. It was also confirmed that when the second temperature _TL was set to less than 500 ° C., the non-combustible component floated from the DPF 31, but did not flow along the exhaust flow and remained in the DPF 31. ..

Here, FIG. 7 schematically shows the relationship between the heating time for the DPF 31, the heating temperature of the DPF 31, and the start of the floating of the incombustible component from the DPF 31 and the end of the flow. In FIG. 7, the broken line indicates the time when the non-combustible component starts to rise from the DPF 31, and the solid line indicates the time when the non-combustible component completes the movement from the DPF 31. As an example, when the DPF31 is heated to 500 ° C., the non-combustible component rises from the DPF31 about 60 minutes after the start of heating, and about 90 minutes after the start of heating, it is completely downstream from this floating position. Can be understood to finish moving to. When the DPF31 is heated to 550 ° C., the non-combustible component rises from the DPF31 about 5 minutes after the start of heating, and about 15 minutes after the start of heating, completely downstream from this floating position. And finish moving. On the other hand, when the DPF 31 is heated to 450 ° C., the non-combustible component rises from the DPF 31 about 90 minutes after the start of heating, but the non-combustible component does not move from this floating position to the downstream side.

Therefore, until the incombustible component is deposited a certain DPF31 performs reproduction processing DPF31 at a high temperature of the first temperature T _H (600 ° C. or higher), when the incombustible component is somewhat deposited DPF31 is cold second It is effective to regenerate the DPF 31 for a predetermined time at the temperature of T _{L (500 to 550 ° C.).} As a result, the non-combustible component can flow to the downstream side of the DPF 31, and the reduction in the effective surface area of the DPF 31 can be suppressed. Even if in any, until the differential pressure [Delta] P between the upstream and downstream sides of the DPF 31 reaches a predetermined value [Delta] P _L, and continues the playback processing of the DPF 31.

The amount of non-combustible component deposited by the DPF31 is basically correlated with the amount of engine oil consumed, but it has also been found to be approximately proportional to the mileage of individual vehicles. .. The relationship between the cumulative mileage O of the vehicle and the accumulated amount of the non-combustible component captured in the DPF 31 is schematically shown in FIG. When the non-combustible component deposited on the DPF 31 is, for example, 10 μm or more, it is effective to remove the non-combustible component. The non-combustible component deposited on the DPF 31 is 10 μm or more, which varies depending on the characteristics of the engine 10 and the operating condition, but as an example, the cumulative mileage O of the vehicle is around 50,000 km. Therefore, the operating state determination unit 16a of the ECU 16 in the present embodiment determines that the DPF 31 needs to be regenerated in order to remove the incombustible component from the DPF 31 when the cumulative mileage O of the vehicle reaches 50,000 km. Then, the cumulative mileage O of the vehicle is reset every time the regeneration process of the DPF 31 at a low temperature is completed. That is, the operating state determination unit 16a of the ECU 16 in the present embodiment also functions as a means for acquiring the accumulated amount of the non-combustible component captured by the filter in the present invention.

Further, the operating condition determining section 16a of the ECU16 is accumulated heating time for the DPF31 in the case of performing heating DPF31 at a second temperature T _L, i.e. to calculate the cumulative heat quantity Q _A, the lifting of incombustible components from DPF31 Determine if it has started. The cumulative heat input Q _A corresponds to a cumulative heating time of 60 minutes when the heating temperature of the DPF 31 is 500 ° C., and corresponds to a cumulative heating time of 5 minutes when the heating temperature of the DPF 31 is 550 ° C. The cumulative heating time changes according to the _{temperature TL.}

In the present embodiment, by heating the DPF 31 at a second temperature T _L, to easily move to a more reliable downstream side of DPF 31 the incombustible component lifted from DPF 31, temporarily the flow rate of the exhaust gas flowing into DPF 31 I am trying to increase it. Specifically, when the vehicle is in the EGR operating region, the opening degree of the EGR control valve 29 is reduced to suppress the exhaust gas recirculation amount, thereby increasing the exhaust flow rate flowing to the DPF 31. When the vehicle is not in the EGR operating region, the air compressor 33 is used to supply compressed air to the exhaust passage 23a between the supercharger 25 and the exhaust purification device 27, and the exhaust flow flow to the DPF 31. To increase. Further, it is possible to increase the exhaust flow rate by increasing the opening degree of the throttle valve 20, but in this case, the fuel injection amount and the injection timing are changed at the same time so that the driving force of the vehicle does not change. There is a need. In any case, it is effective to increase the exhaust flow rate at least over the period from the broken line to the solid line in FIG. 7, and the exhaust flow rate for moving the incombustible component to the downstream side of the DPF 31 is the vehicle. It is preferable to increase or decrease depending on the operating condition of the vehicle and the amount of non-combustible components deposited.

The ECU 16 of the present embodiment includes an air compressor drive unit 16j that controls the operation of the air compressor 33 based on the operating state of the vehicle. The air compressor drive unit 16j operates the air compressor 33 to operate the compressed air when the vehicle is not in the EGR operating region in a state _{where the cumulative input heat amount Q A reaches the threshold value Q R} shown by the broken line in FIG. Is supplied to the exhaust passage 23a on the upstream side of the DPF 31. As a result, it is possible to increase the exhaust flow rate passing through the DPF 31 and promote the incombustible component floating from the DPF 31 to move to the downstream side of the DPF 31.

A differential pressure sensor 34 that detects the pressure difference in the casing 27a on the upstream side and the downstream side of the DPF 31 and outputs the pressure difference to the ECU 16 is attached to the casing 27a of the DPF 31. The differential pressure sensor 34 in the present embodiment functions as a means of the present invention for acquiring the accumulated amount of PM captured in the DPF 31, and provides information for determining whether or not the DPF 31 that has captured the PM needs to be regenerated. It can be given to the ECU 16. When the differential pressure ΔP acquired by the differential pressure sensor 34 _{becomes equal to or higher than the preset threshold value ΔP H} , the operating state determination unit 16a of the ECU 16 determines that the DPF 31 needs to be regenerated. When the differential pressure [Delta] P that is obtained by the differential pressure sensor 34 during the regeneration process of the DPF31 is equal to or less than the threshold value [Delta] P _L which is set in advance, it determines that the reproduction of the DPF31 is required. Instead of such a differential pressure sensor 34, the accumulated amount of PM captured by the DPF 31 is estimated based on the fuel consumption and the like, and the necessity of the regeneration process of the DPF 31 is determined based on the accumulated amount of the PM. You may do so.

The fuel addition valve 26, which has basically the same configuration as the fuel injection valve, is arranged in the exhaust passage 23a between the turbine 25a of the supercharger 25 and the DOC30, and is used as the combustion means of the present invention together with the DOC30 of the exhaust purification device 27. Function. The amount of fuel added from the fuel addition valve 26 is based on the target heating temperature of the DPF 31 set by the ECU 16 and the operating state of the vehicle including the temperature of the DPF 31 and the exhaust air-fuel ratio acquired from the filter temperature sensor 32. , It is set by the fuel addition setting unit 16h of the ECU 16. The fuel addition valve drive unit 16i of the ECU 16 controls the operation of the fuel addition valve 26 so that the fuel set by the fuel addition setting unit 16h is added to the exhaust passage 23a. Target heating temperature of the DPF31 in this embodiment, is set in a case where the first target heating temperature T _H of the hot set when a small amount of deposition of incombustible components deposit amount of incombustible components is equal to or larger than a predetermined value It has a second target heating temperature _TL at a low temperature. From findings described above, the first target heating temperature T _H is set to, for example, about 600 to 650 ° C., the second target heating temperature T _L is set to, for example, about 500-550 ° C..

The ECU 16 grasps the operating state of the engine 10 based on the detection information from the accelerator opening sensor 17, the air flow meter 21, the crank angle sensor 22, the filter temperature sensor 32, the differential pressure sensor 34, and the like. Then, the operation of the fuel injection valve 11, the throttle actuator 19, the EGR control valve 29, the fuel addition valve 26, and the like is controlled so that the engine 10 can be smoothly operated according to a preset program.

Exhaust gas purification procedure in this embodiment will be described with reference to the flowchart of FIG. 9. First, in step S11, whether or not _{the differential pressure ΔP between the upstream side and the downstream side of the DPF 31 is equal to or greater than the first threshold value ΔP H.} Is determined. Here, when the differential pressure [Delta] P between the upstream side and the downstream side of the DPF31 is less than the first threshold [Delta] P _H, i.e. DPF31 determines that there is no need to perform the reproduction process does not clogged, the difference The process of the step S11 is repeated until the pressure ΔP becomes equal to _{or higher than the first threshold value ΔP H.}

In this way, the pressure difference [Delta] P between the upstream side and the downstream side step at the DPF31 of S11 is the first threshold value [Delta] P _H or more, that the DPF31 is required to perform the reproduction process so clogged If it is determined, the process proceeds to step S12. The flag for removing incombustible component determines whether it is set initially the flag is not set, becomes a DPF31 a first temperature T _H and proceeds to S13 in step To heat. Then, the DPF31 at step S14 the differential pressure [Delta] P between the upstream side and the downstream side it is determined whether less than the second threshold value [Delta] P _L, the differential pressure [Delta] P between the upstream side and the downstream side of the DPF31 is second until equal to or less than the threshold value [Delta] P _L, repeats the steps of S14.

In this way, the pressure difference [Delta] P between the upstream side and the downstream side step at the DPF31 in S14 is less than the second threshold [Delta] P _L, that is, when it is determined that the reproduction of the DPF31 is completed, at S15 The step is started and the heating for the regeneration process of DPF31 is stopped. Thereafter, it is determined cumulative travel distance O threshold O _R, whether for example 50000km more at S16 in step. Here, the accumulated travel distance O is the threshold value O _R or more, that is set a flag for if it is determined that it is necessary to remove the non-combustible components from the DPF31 which proceeds to step S17 to process the incombustible component After that, the process returns to the step of S11 described above.

Further, the accumulated travel distance O in the previous S16 in step is less than the threshold value O _R, that is, when it is determined that there is no need to remove the non-combustible components, nothing returns to step S11 without.

When the flag is set in the step S12, that is, when it is determined that it is necessary to remove the incombustible component deposited on the DPF 31, the process proceeds to the step S18 and the DPF 31 becomes _{the second temperature TL.} To heat. At the same time, the cumulative heat input Q _A is calculated. Then, in the step of S19, it is determined whether or not the _{cumulative heat input Q A} is equal to _{or higher than the threshold value Q R.} Here, the accumulated heat quantity Q _A is the threshold value Q _R above, that is, when allowed to flow incombustible component on the downstream side of the DPF31 is determined that it is preferable to prevent the clogging of the DPF, proceeds to step S20 To do. Then, after interrupting the heating of the DPF 31, it is determined in the step of S21 whether or not the vehicle is in the EGR driving region. If it is determined that the vehicle is in the EGR operating region, the process proceeds to step S22 to reduce the opening degree of the EGR control valve 29 so that more exhaust gas flows to the DPF31 side and accumulates on the DPF31. The flow of the non-combustible component to the downstream side of the DPF 31 is promoted. Further, in the step of S21, the vehicle is not in the EGR operating region, that is, the opening degree of the EGR control valve 29 is 0%, and the opening degree of the EGR control valve cannot be narrowed to increase the exhaust flow rate to the DPF 31. If it is determined, the process proceeds to step S23. Then, the air compressor 33 is operated to supply compressed air to the exhaust passage 23a, increase the flow velocity of the exhaust gas flowing to the DPF31 side, and promote the flow of the incombustible component deposited on the DPF31 to the downstream side of the DPF31.

Following the steps S22 and S23 for increasing the flow velocity of the exhaust gas passing through the DPF 31, the timer counts up in the step S24. Then, the count value C _n of the timer is determined whether the threshold value C _R greater than or equal to the preset in step S25, until the count value C _n is equal to or greater than a threshold C _R, repeating the steps of S24, S25. In this way, when it is determined that the count value C _{n of the} timer is equal to or higher than the threshold value C _R , that is, the flow of the incombustible component deposited on the DPF 31 to the downstream side is completed, the process proceeds to the step S26. .. Then, the opening degree of the EGR control valve 29 is returned to an opening degree suitable for the current operating state of the vehicle, or the supply of compressed air by the air compressor 33 is stopped. Further, the cumulative heat input Q _A and the timer count value C _n are reset to 0, the flag is also reset, and the heating of the DPF 31 is restarted so as to _{reach the second temperature TL.}

Thereafter, the differential pressure [Delta] P between the upstream side and the downstream side step at the DPF31 of S27 determines whether less than the second threshold value [Delta] P _L, the differential pressure [Delta] P between the upstream side and the downstream side of the DPF31 is second until the following threshold [Delta] P _L, it repeats the steps of S27.

In this way, the pressure difference [Delta] P between the upstream side and the downstream side step at the DPF31 of S27 is less than the second threshold [Delta] P _L, that is, when it is determined that the reproduction of the DPF31 is completed, the S28 Move to step. Then, after stopping the heating for the regeneration process of DPF31, the process returns to the step of S11.

On the other hand, the accumulated heat quantity Q _A at step S19 is less than the threshold value Q _R, that is, when it is determined that it is not necessary to still flowing incombustible component on the downstream side of the DPF31, the process proceeds to the previous step S27 .. Then, it is determined whether or not the differential pressure ΔP between the upstream side and the downstream side of the DPF 31 is equal to or less than the second threshold value ΔP _{L, and the differential pressure ΔP between the upstream side and the downstream side of the DPF 31 is equal to or less than the second threshold value ΔP L.} The step S27 is repeatedly executed until the result is reached.

It should be noted that the present invention should be construed only from the matters described in the claims, and even in the above-described embodiment, other than the matters described by all the changes and modifications included in the concept of the present invention. It is possible. That is, all the matters in the above-described embodiment are not for limiting the present invention, and may be arbitrarily changed according to the use, purpose, etc., including the configuration not directly related to the present invention. It is a thing.

10 Engine 16a Operating condition judgment unit 16h Fuel addition setting unit 16i Fuel addition valve drive unit 23a Exhaust passage 26 Fuel addition valve 27 Exhaust purification device 30 DOC
31 Catalyzed DPF
34 differential pressure sensor O cumulative travel distance O _R upstream and downstream side of the differential pressure [Delta] P _H differential pressure for the first threshold value T _H first target heating temperature T _L second target heating temperature threshold [Delta] P DPF about cumulative travel distance

Claims (1)

A filter that is placed in the exhaust passage of an internal combustion engine mounted on a vehicle and captures flammable particulate matter and non-combustible components contained in the exhaust flowing through this exhaust passage.
A means of obtaining the amount of particulate matter trapped in this filter,
A combustion means for burning the particulate matter captured by the filter, and
A means for obtaining the accumulated amount of non-combustible components captured by the filter, and
An exhaust gas purification device including an EGR control valve provided in the vehicle and a control means for controlling the drive of an air compressor together with the operation of the combustion means.
When the amount of particulate matter trapped in the filter is equal to or greater than the first predetermined value and the amount of non-combustible component deposited in the filter is less than the second predetermined value, the temperature of the filter is the first. Control the operation of the combustion means so that it becomes the temperature,
When the accumulated amount of particulate matter captured by the filter is equal to or greater than the first predetermined value and the accumulated amount of non-combustible components captured by the filter is equal to or greater than the second predetermined value, the temperature of the filter is set to the above. At a second temperature lower than the first temperature, if the vehicle is in the EGR operating region, the opening degree of the EGR control valve is reduced, or if the vehicle is not in the EGR operating region, the air compression is performed. An exhaust gas purification device characterized in that the operation of the combustion means is controlled so as to increase the flow passing through the filter by supplying compressed air from the outside to the exhaust passage by the machine.

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