JP4367369B2 - Internal combustion engine exhaust purification system - Google Patents

Description

  The present invention filters the particulate matter in the exhaust discharged from the combustion chamber of the internal combustion engine and oxidizes and purifies the deposited particulate matter by a temperature raising process, and the unburned exhaust in the exhaust The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that achieves an oxidation catalyst function capable of oxidizing and purifying components in an exhaust gas purification unit composed of a single part or multiple parts.

  2. Description of the Related Art Conventionally, sulfur compounds such as sulfate that are present in fuel are deposited on an exhaust purification unit disposed in an exhaust system of an internal combustion engine, specifically, a filter that supports an oxidation catalyst. If such a sulfur compound is left as it is, it will affect the performance of the oxidation catalyst, corrode the filter vessel, or exhaust depending on the operating state of the internal combustion engine or the regeneration state of the particulate matter purification filter provided upstream. When the temperature rises, a high concentration of sulfur compounds may be released to the outside.

In order to prevent such a problem, when it is determined from the operation history of the internal combustion engine that the sulfur compound is accumulated on the filter to some extent, the temperature increase process of the filter is executed, so that the sulfur compound accumulation amount is reduced. Within a small amount, processing for discharging from the filter is performed (for example, see Patent Documents 1 and 2).
Japanese Patent Laying-Open No. 2003-206729 (page 3-5, FIG. 3) JP 2004-116461 A (page 6-7, FIG. 4)

  Apart from such a sulfur compound release process, the exhaust system of the internal combustion engine performs a purification process of particulate matter deposited on the filter. This particulate matter purification process is the same as the sulfur compound release process in that the temperature of the filter is increased. Therefore, at the same time as the particulate matter purification treatment, a sulfur compound is released.

  However, in Patent Documents 1 and 2, since the temperature raising process for releasing the sulfur compound is performed independently of the temperature raising process for purifying the particulate matter, the sulfur compound actually deposited In some cases, the amount of accumulated sulfur compound is larger than that assumed in the sulfur compound releasing process. For this reason, during the temperature rising process for releasing the sulfur compound, the temperature rising process is performed in excess of the degree of the temperature rising process necessary to actually release the entire amount of the sulfur compound deposit, and the temperature rising energy of the fuel, etc. In some cases, waste may occur and fuel consumption may deteriorate.

  This is the same for the particulate matter purification treatment side, and the particulate matter is also purified simultaneously with the sulfur compound release treatment. Therefore, there are cases where the amount of accumulated particulate matter assumed in the particulate matter purification process is larger than the particulate matter that is actually deposited, and there is an excess during the temperature rise treatment for particulate matter purification. The temperature raising process is executed, and the fuel consumption may be similarly deteriorated.

  An object of the present invention is to prevent an excessive temperature increase process by considering the relationship between the temperature increase process of the particulate matter purification process and the sulfur compound release process in the internal combustion engine exhaust gas purification apparatus. is there.

In the following, means for achieving the above object and its effects are described.
The internal combustion engine exhaust gas purification apparatus according to claim 1 is a particulate material capable of filtering particulate matter in the exhaust discharged from the combustion chamber of the internal combustion engine and oxidizing the deposited particulate matter by a temperature raising process to purify the particulate matter. and substance purification function, an oxidation catalyst function of the unburned components in the exhaust can be purified by oxidizing, an internal combustion engine exhaust purification apparatus that is realized by the exhaust gas purification unit comprising a single or a plurality of portions, the exhaust gas purifying When the sulfur compound deposition amount at the head reaches the required discharge amount, and when the execution condition of the sulfur compound release processing for releasing the sulfur compound to the exhaust downstream side by the temperature raising processing is satisfied, the sulfur compound is deposited on the exhaust purification section. When the degree of the temperature raising process necessary for the purification of the particulate matter is greater than or equal to the degree of the temperature raising process required for the sulfur compound releasing process, the particulate matter deposited in the exhaust purification unit is removed. Heating treatment to purify Characterized by comprising an exhaust gas purification control unit for the line.

  As described above, the temperature increasing process for releasing the sulfur compound is not a process independent of the temperature increasing process for purifying the particulate matter. The relationship is taken into consideration. In other words, if the degree of the temperature rising process that can purify the amount of particulate matter accumulated is greater than the degree of the temperature rising process required for the sulfur compound releasing process, the temperature rising process is executed as the particulate matter purifying process. is doing.

  This realizes complete release of the sulfur compound at the same time as complete purification of the particulate matter by the temperature raising process that oxidizes and purifies the amount of particulate matter accumulated. As described above, the control is performed in consideration of the release of the sulfur compound in the temperature raising process of the particulate matter purification process, so that the actual sulfur compound deposition amount and the sulfur compound deposition amount assumed in the sulfur compound release treatment are The same state can be maintained. For this reason, compared with the case where the temperature rising process is independent between the sulfur compound releasing process and the particulate matter purification process, an excessive temperature rising process during the sulfur compound releasing process is prevented.

  The internal combustion engine exhaust gas purification apparatus according to claim 2, wherein, in claim 1, the exhaust gas purification control means is one of fuel addition to the exhaust gas purification unit and high temperature of exhaust gas discharged from the combustion chamber of the internal combustion engine. Or the exhaust system temperature raising means for performing the temperature raising process by both, and the particulate matter accumulated in the exhaust purification unit when the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount Particulate matter purification means for controlling the exhaust system temperature raising means to purify the substance, and when the amount of sulfur compound deposited in the exhaust purification unit reaches the required release deposition amount, the particulate matter at the present time If it is determined that the release of the total amount of the sulfur compound deposit is insufficient at the extent of the temperature raising process for purifying the deposit amount, the temperature of the exhaust system is increased so that the temperature rise process for releasing the total amount of the sulfur compound deposit is performed. Control the temperature means and insufficient If not constant, is characterized in that a sulfur compound release means for controlling the exhaust system Atsushi Nobori means to perform a Atsushi Nobori process of the total amount purifying the particulate matter accumulation amount.

  More specifically, the exhaust purification control means can be configured to include an exhaust system temperature raising means, a particulate matter purification means, and a sulfur compound release means. Among them, the sulfur compound releasing means determines the amount of sulfur compound deposited according to the degree of the temperature increasing process for purifying the current amount of particulate matter accumulated as described above when the amount of sulfur compound deposited reaches the required amount of release. Is selected from the temperature rising process for releasing the entire amount of the gas and the temperature rising process for purifying the amount of the particulate matter accumulated in its entirety.

  In particular, if it is determined that the release of the total amount of sulfur compound deposits is insufficient with the degree of the temperature rise process that purifies the total amount of particulate matter accumulated at the present time, the temperature rise process that releases the entire amount of sulfur compound deposits Is running. Therefore, since all the sulfur compounds can be surely released and the sulfur compounds can be prevented from accumulating excessively, problems such as white smoke do not occur. In addition, if the release of the total amount of sulfur compound deposits is sufficient, the temperature rise treatment to purify all of the particulate matter deposition amount is executed at the extent of the temperature raising treatment that purifies the entire amount of particulate matter deposition amount, The effects as described in the first aspect are produced, and an excessive temperature increase process during the sulfur compound releasing process is prevented.

The internal combustion engine exhaust gas purification apparatus according to claim 3 is a particulate material capable of filtering particulate matter in the exhaust discharged from the combustion chamber of the internal combustion engine and oxidizing the deposited particulate matter by a temperature raising process to purify the particulate matter. and substance purification function, an oxidation catalyst function of the unburned components in the exhaust can be purified by oxidizing, an internal combustion engine exhaust purification apparatus that is realized by the exhaust gas purification unit comprising a single or a plurality of portions, the exhaust gas purifying When the execution condition of the particulate matter purification treatment for purifying the particulate matter by the temperature rising process is established when the particulate matter deposition amount at the part reaches the regeneration required accumulation amount, the particulate matter is deposited on the exhaust purification unit. When the degree of the temperature raising process required for releasing the sulfur compound is equal to or higher than the degree of the temperature raising process required for the particulate matter purification process, the sulfur compound deposited in the exhaust purification unit is disposed downstream of the exhaust gas. The temperature rising process released to the side Characterized by comprising an exhaust gas purification control unit for the line.

  Thus, the temperature raising process for particulate matter purification is not a process independent of the temperature raising process for sulfur compound release, and the sulfur compound release treatment is performed when the particulate matter purification process is performed. The relationship is taken into consideration. In other words, if the degree of the temperature raising process that can release the sulfur compound deposit amount is equal to or higher than the degree of the temperature raising process required for the particulate matter purification process, the temperature raising process is executed as the sulfur compound releasing process. ing.

  As a result, the particulate matter is completely purified simultaneously with the complete release of the sulfur compound by the temperature raising process for releasing the accumulated amount of the sulfur compound. In this way, the control takes into account the purification of particulate matter in the temperature rise treatment of the sulfur compound release treatment, so the actual particulate matter deposition amount and particulate matter deposition assumed in the particulate matter purification treatment Can maintain the same state as the quantity. For this reason, compared with the case where the temperature rising process is independent between the particulate matter purification process and the sulfur compound releasing process, the excessive temperature raising process during the particulate matter purification process is prevented.

  According to a fourth aspect of the present invention, there is provided an internal combustion engine exhaust gas purification apparatus according to the third aspect, wherein the exhaust gas purification control means is one of adding fuel to the exhaust gas purification unit and increasing the temperature of exhaust gas discharged from the combustion chamber of the internal combustion engine. Alternatively, the exhaust system temperature raising means for performing the temperature raising process by both, and the sulfur compound deposited in the exhaust purification unit when the amount of sulfur compound deposition in the exhaust purification unit reaches the required discharge amount A sulfur compound releasing means for controlling the exhaust system temperature raising means to release, and when the particulate matter deposition amount in the exhaust purification unit reaches a regeneration required deposition amount, the current sulfur compound deposition amount is If it is determined that the purification of the total amount of the particulate matter deposition amount is insufficient with the extent of the temperature raising treatment for releasing the entire amount, the exhaust system temperature rise is performed so as to execute the temperature rise treatment for purifying the particulate matter deposition amount in its entirety. Control means and inadequate If not constant, it is characterized in that a particulate matter purifying device for controlling the exhaust system Atsushi Nobori means to perform a Atsushi Nobori process to release the whole amount the sulfur compounds deposit amount.

  More specifically, the exhaust purification control means can be configured as an exhaust system temperature raising means, a sulfur compound releasing means, and a particulate matter purification means. Among them, the particulate matter purifying means determines whether the particulate matter deposition amount depends on the degree of the temperature raising process that releases the entire amount of the present sulfur compound deposition amount when the particulate matter accumulation amount reaches the regeneration required deposition amount as described above. A temperature increasing process for releasing the entire amount and a temperature increasing process for purifying the amount of accumulated particulate matter are selected.

  In particular, if it is determined that the purification of the particulate matter deposition amount is insufficient with the degree of the temperature raising treatment that releases the entire amount of the sulfur compound deposition amount at the present time, the temperature rise for purifying the particulate matter deposition amount in its entirety Processing is being executed. Therefore, since all the particulate matter can be reliably purified and the particulate matter can be prevented from accumulating excessively, problems such as clogging do not occur. In addition, if the total amount of particulate matter deposition amount is sufficiently purified at the degree of the temperature raising treatment that releases the entire amount of sulfur compound deposit, the temperature rise treatment that releases the entire amount of sulfur compound deposit is executed. The effect as described in claim 3 is produced, and an excessive temperature rise process during the particulate matter purification process is prevented.

The internal combustion engine exhaust gas purification apparatus according to claim 5 is a particulate material capable of filtering particulate matter in exhaust gas discharged from a combustion chamber of the internal combustion engine and oxidizing the deposited particulate matter by a temperature raising process to purify the particulate matter. and substance purification function, an oxidation catalyst function of the unburned components in the exhaust can be purified by oxidizing, an internal combustion engine exhaust purification apparatus that is realized by the exhaust gas purification unit comprising a single or a plurality of portions, the exhaust gas purifying When the sulfur compound deposition amount at the head reaches the required discharge amount, and when the execution condition of the sulfur compound release processing for releasing the sulfur compound to the exhaust downstream side by the temperature raising processing is satisfied, the sulfur compound is deposited on the exhaust purification section. When the degree of the temperature raising process necessary for the purification of the particulate matter is higher than the degree of the temperature raising process required for the sulfur compound releasing process, the particulate matter deposited in the exhaust purification unit is purified. Execute temperature rise process Sometimes execution condition of the particulate matter purifying process particulate matter deposit amount in the exhaust gas purifying portion for purifying the particulate matter at elevated process by reaching the playback request deposition amount is satisfied, the exhaust gas purifying unit When the degree of the temperature raising process required for releasing the sulfur compound deposited on the exhaust gas is higher than the degree of the temperature raising process required for the particulate matter purification process, the sulfur compound deposited in the exhaust purification unit is removed. An exhaust purification control means for performing a temperature raising process for discharging to the exhaust downstream side is provided.

  In this way, the exhaust gas purification control means is provided with the functions of both the exhaust gas purification control means described in claim 1 and the exhaust gas purification control means described in claim 3, so that the particulate matter can be obtained. Simultaneous purification and complete release of sulfur compounds. As a result, it is possible to maintain the same state of the actual sulfur compound deposition amount and the sulfur compound deposition amount assumed in the sulfur compound releasing treatment, and further, in the actual particulate matter deposition amount and the particulate matter purification treatment. The same state as the assumed particulate matter accumulation amount can be maintained.

Therefore, an excessive temperature rise process can be prevented both during the sulfur compound release process and during the particulate matter purification process.
The internal combustion engine exhaust gas purification apparatus according to claim 6, wherein the exhaust gas purification control means is one of fuel addition to the exhaust gas purification unit and high temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine. Or the exhaust system temperature raising means for performing the temperature raising process by both, and the sulfur compound in the exhaust purification unit at the present time when the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount If it is determined that the total amount of particulate matter deposited amount is not sufficiently purified at the extent of the temperature raising process for releasing the entire amount of deposit, the exhaust gas is performed so as to execute the temperature raising process for purifying the particulate matter deposited amount in its entirety. A particulate matter purification means for controlling the exhaust system temperature raising means so as to execute a temperature raising process for releasing the total amount of the sulfur compound deposit, Accumulation of sulfur compounds in the exhaust purification section When the amount of deposits required to be released has reached the amount required to be released, it is determined that the release of the total amount of sulfur compound deposits is insufficient with the extent of the temperature raising process that purifies all the particulate matter deposits in the exhaust gas purification unit at the present time. For example, the exhaust system temperature raising means is controlled to execute a temperature raising process for releasing the total amount of the sulfur compound deposit, and if it is not determined to be insufficient, the temperature rise process for purifying the particulate matter accumulation quantity in its entirety. And a sulfur compound releasing means for controlling the exhaust system temperature raising means.

  More specifically, the exhaust purification control means can be configured as including an exhaust system temperature raising means, a particulate matter purification means, and a sulfur compound releasing means. In addition, the particulate matter purification means has the same configuration as that of the particulate matter purification means of claim 4, and the sulfur compound release means has the same configuration as that of the sulfur compound release means of claim 2. For this reason, the effects of both of the second and fourth aspects can be produced, and an excessive temperature rise process can be prevented both during the sulfur compound releasing process and during the particulate matter purification process.

  The internal combustion engine exhaust gas purification apparatus according to claim 7, wherein the exhaust gas purification unit filters the particulate matter and oxidizes and purifies the NOx purification catalyst and the particulate matter in any one of claims 1 to 6. At least two parts, an exhaust purification part carrying a catalyst to be carried, and an exhaust purification part carrying an oxidation catalyst provided on the exhaust downstream side of the exhaust purification part for oxidizing and purifying unburned components in the exhaust gas It is provided with a part.

  More specifically, the exhaust purification unit may include at least two exhaust purification parts described above. In such a configuration, as described in any one of the first to sixth aspects, an excessive temperature increase process is prevented during the sulfur compound releasing process or the particulate matter purification process.

[Embodiment 1]
FIG. 1 is an explanatory diagram showing the outline of a vehicle diesel engine to which the above-described invention is applied and a control system that functions as an internal combustion engine combustion control device. The present invention can also be applied to a case where a similar catalyst configuration is adopted for a lean combustion gasoline engine or the like.

  The diesel engine 2 includes a plurality of cylinders, here, four cylinders # 1, # 2, # 3, and # 4. Other cylinder numbers may be used. The combustion chambers 4 of the cylinders # 1 to # 4 are connected to a surge tank 12 via an intake port 8 and an intake manifold 10 that are opened and closed by an intake valve 6. The surge tank 12 is connected to the intercooler 14 via the intake passage 13 and further connected to the supercharger, here, the outlet side of the compressor 16a of the exhaust turbocharger 16. The inlet side of the compressor 16 a is connected to an air cleaner 18. The surge tank 12 has an EGR gas supply port 20 a of an exhaust gas recirculation (hereinafter referred to as “EGR”) path 20. A throttle valve 22 is disposed in the intake passage 13 between the surge tank 12 and the intercooler 14, and an intake air amount sensor 24 and an intake air temperature sensor 26 are disposed between the compressor 16 a and the air cleaner 18. .

  The combustion chambers 4 of the cylinders # 1 to # 4 are connected to the inlet side of the exhaust turbine 16b of the exhaust turbocharger 16 via an exhaust port 30 and an exhaust manifold 32 that are opened and closed by an exhaust valve 28, and the outlet of the exhaust turbine 16b. The side is connected to the exhaust passage 34. The exhaust turbine 16b introduces exhaust from the fourth cylinder # 4 side in the exhaust manifold 32.

  In the exhaust passage 34, three catalytic converters 36, 38 and 40 in which an exhaust purification catalyst is housed are arranged. The most upstream first catalytic converter 36 houses a NOx storage reduction catalyst 36a. When the exhaust gas is in an oxidizing atmosphere (lean) during normal operation of the diesel engine 2, NOx is stored in the NOx storage reduction catalyst 36a. In the reducing atmosphere (stoichiometric or air / fuel ratio lower than stoichiometric), the NOx occluded in the NOx occlusion reduction catalyst 36a is released as NO and is reduced by HC or CO. In this way, NOx is purified.

  The second catalytic converter 38 arranged second is accommodated with a filter 38a having a wall portion formed in a monolith structure, and exhaust gas passes through the minute holes in the wall portion. Since a layer of a NOx occlusion reduction catalyst (corresponding to a NOx purification catalyst) is formed on the surface of the micropores of the filter 38a, it functions as an exhaust purification catalyst and NOx purification is performed as described above. Further, particulate matter (hereinafter referred to as “PM”) in the exhaust is trapped and deposited on the filter wall. The deposited PM is made into a high-temperature oxidizing atmosphere, so that the oxidation of PM is started by active oxygen generated during NOx occlusion, and the entire PM is further oxidized by excess oxygen in the vicinity. As a result, NOx purification and PM oxidation purification are executed. Here, the first catalytic converter 36 and the second catalytic converter 38 are formed in an integrated configuration.

The most downstream third catalytic converter 40 contains an oxidation catalyst 40a, where HC and CO are oxidized and purified.
The combination of the NOx occlusion reduction catalyst 36a, the filter 38a, and the oxidation catalyst 40a corresponds to the exhaust purification unit of the claims. Of these, the filter 38a corresponds to an exhaust purification portion that filters PM and carries a NOx purification catalyst and a catalyst that oxidizes and purifies PM, and the oxidation catalyst 40a is located downstream of the filter 38a on the exhaust side. It corresponds to an exhaust purification portion that is provided and carries an oxidation catalyst that oxidizes and purifies unburned components in the exhaust.

  A first exhaust temperature sensor 44 is disposed between the NOx storage reduction catalyst 36a and the filter 38a. Further, between the filter 38a and the oxidation catalyst 40a, a second exhaust temperature sensor 46 is disposed near the filter 38a, and an air-fuel ratio sensor 48 is disposed near the oxidation catalyst 40a.

  Here, the air-fuel ratio sensor 48 uses a solid electrolyte, and is a sensor that detects the air-fuel ratio of the exhaust based on the exhaust component and linearly outputs a voltage signal proportional to the air-fuel ratio. The first exhaust temperature sensor 44 and the second exhaust temperature sensor 46 detect the exhaust temperatures thci and thco at their respective positions.

  Piping of the differential pressure sensor 50 is provided on the upstream side and the downstream side of the filter 38a, respectively, and the differential pressure sensor 50 is located upstream and downstream of the filter 38a in order to detect the degree of clogging of the filter 38a, that is, the degree of PM accumulation. Is detected.

  The exhaust manifold 32 has an EGR gas inlet 20b of the EGR path 20 opened. The EGR gas inlet 20b is open on the first cylinder # 1 side, and is on the opposite side to the fourth cylinder # 4 side where the exhaust turbine 16b introduces exhaust.

  In the middle of the EGR path 20, an iron-based EGR catalyst 52 for reforming EGR gas is disposed from the EGR gas inlet 20b side, and an EGR cooler 54 for cooling the EGR gas is further provided. The EGR catalyst 52 also has a function of preventing the EGR cooler 54 from being clogged. An EGR valve 56 is disposed on the EGR gas supply port 20a side. By adjusting the opening degree of the EGR valve 56, the amount of EGR gas supplied from the EGR gas supply port 20a to the intake system can be adjusted.

  A fuel injection valve 58 disposed in each cylinder # 1 to # 4 and directly injecting fuel into each combustion chamber 4 is connected to a common rail 60 via a fuel supply pipe 58a. Fuel is supplied into the common rail 60 from an electrically controlled discharge variable fuel pump 62, and the high-pressure fuel supplied from the fuel pump 62 into the common rail 60 is supplied to each fuel injection valve 58 through each fuel supply pipe 58a. Distributed supply. A fuel pressure sensor 64 for detecting the fuel pressure is attached to the common rail 60.

  Further, low pressure fuel is separately supplied from the fuel pump 62 to the addition valve 68 via the fuel supply pipe 66. The addition valve 68 is provided in the exhaust port 30 of the fourth cylinder # 4, and adds fuel into the exhaust by injecting fuel toward the exhaust turbine 16b. The catalyst control mode described later is executed by this fuel addition.

  An electronic control unit (hereinafter referred to as “ECU”) 70 is mainly configured by a digital computer including a CPU, a ROM, a RAM, and the like, and a drive circuit for driving various devices. The ECU 70 includes the intake air amount sensor 24, the intake air temperature sensor 26, the first exhaust temperature sensor 44, the second exhaust temperature sensor 46, the air-fuel ratio sensor 48, the differential pressure sensor 50, the EGR opening sensor in the EGR valve 56, Signals from the fuel pressure sensor 64 and the throttle opening sensor 22a are read. Further, signals are read from an accelerator opening sensor 74 that detects the amount of depression of the accelerator pedal 72 (accelerator opening ACCP) and a cooling water temperature sensor 76 that detects the cooling water temperature THW of the diesel engine 2. Further, signals are read from an engine speed sensor 80 that detects the rotational speed NE (rpm) of the crankshaft 78, and a cylinder discrimination sensor 82 that detects the rotational phase of the crankshaft 78 or the rotational phase of the intake cam and performs cylinder discrimination. Yes.

  Based on the engine operating state obtained from these signals, the ECU 70 executes fuel injection amount control and fuel injection timing control by the fuel injection valve 58. Further, the opening degree control of the EGR valve 56, the throttle opening degree control by the motor 22b, the discharge amount control of the fuel pump 62, and the PM regeneration control, S poison recovery control or NOx reduction control which will be described later by the valve opening control of the addition valve 68, etc. Perform catalyst control and other processes.

  As the combustion mode control executed by the ECU 70, a combustion mode selected from two types of a normal combustion mode and a low temperature combustion mode is executed according to the operating state. Here, the low-temperature combustion mode is a combustion mode in which NOx and smoke are simultaneously reduced by slowing the increase in the combustion temperature by a large amount of exhaust gas recirculation using the EGR valve opening map for low-temperature combustion mode. This low-temperature combustion mode is executed in the low-load low-medium rotation region, and air-fuel ratio feedback control is performed by adjusting the throttle opening TA based on the air-fuel ratio AF detected by the air-fuel ratio sensor 48. The combustion mode other than this is a normal combustion mode in which normal EGR control (including the case where EGR is not performed) is executed using the normal combustion mode EGR valve opening degree map.

  There are four types of catalyst control modes for performing catalyst control for the exhaust purification catalyst, mainly the filter 38a, including a PM regeneration control mode, an S poison recovery control mode, a NOx reduction control mode, and a normal control mode.

  In the PM regeneration control mode, when the estimated accumulation amount of PM (hereinafter referred to as PM accumulation amount PMsm) reaches the regeneration required accumulation amount, the temperature of the PM accumulated on the filter 38a in the second catalytic converter 38 is raised. As described above, this is a mode for executing the temperature raising process for PM purification that is combusted by oxidation and discharged as CO2 and H2O. In this mode, fuel addition from the addition valve 68 is repeated in an air-fuel ratio state higher than stoichiometric (theoretical air-fuel ratio) to raise the catalyst bed temperature (for example, 600 to 700 ° C.). There is a case where after-injection that is fuel injection into the combustion chamber 4 in the stroke or exhaust stroke is added. Even if the PM accumulation amount PMsm does not reach the regeneration required accumulation amount, the increase in the pressure for PM purification increases when the differential pressure ΔP upstream and downstream of the filter 38a detected by the differential pressure sensor 50 increases. The temperature treatment is performed to purify the PM accumulated on the filter 38a by burning it by oxidation at a high temperature. The PM deposition amount PMsm is a total discharge amount per unit time of PM discharged from the combustion chamber 4 and PM discharged by fuel added from the addition valve 68, and per unit time due to oxidation in the filter 38a. This is a value obtained by estimating the amount of PM deposited on the filter 38a as time elapses from the difference from the purification amount.

  In addition, you may perform the burn-up type temperature rising process by an intermittent addition process in PM regeneration control mode. In the intermittent addition process, the air-fuel ratio is lowered or stoichiometrically lower than the stoichiometric air fuel ratio by intermittent fuel addition from the addition valve 68 at intervals of no fuel addition. Here, enrichment is performed to make the air-fuel ratio slightly lower than stoichiometric. Even in this process, after-injection by the fuel injection valve 58 may be applied. As a result, a PM burning-out (burn-up) action is generated to eliminate the PM clogging of the front end face of the NOx storage reduction catalyst 36a, or to burn out the PM deposited in the filter 38a.

  The S-poisoning recovery control mode is a mode in which when the NOx occlusion reduction catalyst 36a and the filter 38a are poisoned with S (sulfur) and the NOx occlusion capability is reduced, the S component is released to recover from the S poisoning. In this mode, fuel addition is repeated from the addition valve 68 to execute a temperature raising process for raising the catalyst bed temperature (for example, 650 ° C.), and the air-fuel ratio is stoichiometrically or stoichiometrically by intermittent fuel addition from the addition valve 68. An air-fuel ratio reduction process is performed to make the air-fuel ratio slightly lower than Here, enrichment is performed to make the air-fuel ratio slightly lower than stoichiometric. In this mode, after-injection by the fuel injection valve 58 may be added.

  The NOx reduction control mode is a mode in which the NOx occluded in the NOx occlusion reduction catalyst 36a and the filter 38a is reduced to N2, CO2 and H2O and released. In this mode, by intermittent fuel addition from the addition valve 68 with a relatively long time, the catalyst bed temperature is relatively low (for example, 250 to 500 ° C.), and the air-fuel ratio is reduced or lower than the stoichiometry. .

It should be noted that states other than these three catalyst control modes become the normal control mode, and in this normal control mode, fuel addition from the addition valve 68 and after-injection by the fuel injection valve 58 are not performed.
Further, regarding the oxidation catalyst 40a in the third catalytic converter 40 at the most downstream, the sulfur compound deposition amount, here, the sulfate deposition amount SULFsm, is the fuel amount from the fuel injection valve 58 and the catalyst bed temperature (here, the exhaust temperature thco). It is calculated based on etc. When the sulfate accumulation amount SULFsm reaches the required release accumulation amount EGSULF, a process of releasing the sulfur compound deposited on the oxidation catalyst 40a downstream of the exhaust gas by increasing the temperature by the same temperature increase process as the PM purification temperature increase process is performed. Is going. This required emission accumulation amount EGSULF is set so that the exhaust sulfate concentration does not affect the ecosystem even if the sulfur compound is released downstream at this accumulation amount.

  FIG. 2 shows a flowchart of the sulfate release control process executed by the ECU 70, and FIG. 3 shows a flowchart of the PM regeneration control process. Each process is a process that is interrupted and executed at a constant time period. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When the sulfate release control process (FIG. 2) is started, it is first determined whether or not the temperature raising process for releasing the sulfate is being executed (S102). Here, the temperature raising process for releasing the sulfate is a temperature raising process performed based on a request ON (ON) in any of steps S110 and S112 described later.

  If the corresponding temperature raising process is not being executed (“yes” in S102), then the calculation of the sulfate accumulation amount SULFsm in the oxidation catalyst 40a is executed as shown in Equation 1 (S104).

[Formula 1] SULFsm ← SULFsm + ΔSULF
The sulfate accumulation amount SULFsm on the right side of Equation 1 is a value calculated at the time of the previous main processing execution. The sulfate accumulation amount fluctuation value ΔSULF corresponds to the amount of sulfate accumulated on the oxidation catalyst 40a during one control cycle. The sulfate accumulation amount fluctuation value ΔSULF is the amount of fuel used for combustion in the diesel engine 2 (main injection amount), the catalyst bed temperature of the oxidation catalyst 40a, and the S poison amount for the NOx storage reduction catalyst 36a and the filter 38a. Based on the map obtained by experiments in advance, there may be a negative value. However, if a negative value is calculated for the sulfate accumulation amount SULFsm on the left side, 0 (g) is set for the sulfate accumulation amount SULFsm on the left side, so that a negative value is set for the sulfate accumulation amount SULFsm. Absent.

  When the current sulfate accumulation amount SULFsm is calculated in this way, it is determined whether or not the sulfate release condition is satisfied (S106). This sulfate release condition is satisfied when the sulfate accumulation amount SULFsm calculated in the immediately preceding step S104 reaches the release request accumulation amount EGSULF. It should be noted that the sulfate release condition may be satisfied under other conditions before the sulfate accumulation amount SULFsm reaches the release required accumulation amount EGSULF.

If the sulfate release condition is not satisfied (“no” in S106), this process is temporarily terminated as it is.
In this manner, the state in which the sulfate release condition is not satisfied is repeated, and when the sulfate accumulation amount SULFsm gradually increases and SULFsm ≧ EGSULF is satisfied, the sulfate release condition is satisfied (“yes” in S106). . Therefore, the relationship of Expression 2 is evaluated next (S108).

[Formula 2] SULFsm> EGPMsulf (PMsm)
Here, EGPMsulf (PMsm) on the right side is a map or a relational expression for calculating the amount of sulfate deposit that can be released when a temperature increase process that can purify the current PM deposit amount PMsm is applied to sulfate release. In other words, EGPMsulf (PMsm) indicates the sulfate accumulation amount released from the oxidation catalyst 40a at the same time when the temperature raising process for purifying the PM accumulation amount PMsm of the filter 38a is performed.

  If Equation 2 is satisfied (“yes” in S108), that is, if the amount of sulfate accumulated on the oxidation catalyst 40a cannot be released by the temperature raising process for purifying the PM accumulation amount PMsm of the filter 38a in its entirety, The sulfate release request for releasing the sulfate accumulation amount SULFsm is set to ON (S110).

  By setting the sulfate release request ON corresponding to the sulfate accumulation amount SULFsm, the ECU 70 repeatedly adds fuel into the exhaust from the addition valve 68, whereby the added fuel burns in the NOx storage reduction catalyst 36a and the filter 38a to generate heat. Then, the temperature raising process for increasing the temperature of the exhaust is started. With this high-temperature exhaust, the oxidation catalyst 40a is heated to a temperature at which sulfate can be released. The degree of the temperature raising process, here, the temperature level and the temperature raising period are controlled by the ECU 70 so that the entire amount of the sulfate accumulation amount SULFsm is released. At the same time, the entire amount of PM in the filter 38a is purified.

  If Equation 2 is not satisfied (“no” in S108), that is, if the sulfate accumulated on the oxidation catalyst 40a can be released at the same time by the temperature raising process for purifying the PM accumulation amount PMsm of the filter 38a, the sulfate release is performed. Therefore, a PM regeneration request for purifying the current PM accumulation amount PMsm is set to ON (S112).

  By setting the PM regeneration request ON corresponding to this PM accumulation amount PMsm, the ECU 70 repeatedly adds fuel into the exhaust from the addition valve 68, whereby the added fuel burns in the NOx storage reduction catalyst 36a and the filter 38a to generate heat. PM is purified by oxidation. At the same time, the exhaust gas heated to a high temperature raises the oxidation catalyst 40a to a temperature at which sulfate can be released. The degree of the temperature raising process is executed by the ECU 70 so as to purify the PM deposition amount PMsm, but the degree of the temperature raising process corresponding to the PM deposition amount PMsm at this time is the sulfate accumulation amount SULFsm. Is more than the extent of the temperature raising treatment that can release all of the amount simultaneously. Therefore, it is possible to completely release the total amount of sulfate deposit SULFsm.

  In the next control cycle in which the process of step S110 or step S112 is performed, the temperature increasing process for releasing the sulfate is started (“no” in S102), and therefore 0 g is set to the sulfate accumulation amount SULFsm (S114). ). Thereafter, the process of step S114 is repeated until the corresponding temperature raising process is completed.

The PM regeneration control process (FIG. 3) will be described. When this processing is started, first, the PM accumulation amount PMsm (g) is calculated as shown in Equation 3 (S152).
[Formula 3] PMsm <-PMsm + PMeng + PMexij-PMctox
Here, the PM accumulation amount PMsm on the right side of Expression 3 is a value calculated at the time of the previous main processing execution. The engine PM emission amount PMeng is the amount of PM discharged based on the combustion in the combustion chamber 4 according to the operation state of the diesel engine 2 in one control cycle. The PM addition amount PMexij derived from fuel addition is the amount of PM added to the exhaust by fuel injection from the addition valve 68 in one control cycle. The oxidized PM amount PMctox is a PM amount that is purified by oxidation in the filter 38a and disappears in one control cycle.

  Next, it is determined whether or not PM regeneration processing is in progress (S154). If the PM regeneration process is not in progress (“yes” in S154), it is next determined whether or not the PM regeneration condition is satisfied (S156). The PM regeneration condition is the following condition, and is satisfied when any one of the conditions is satisfied.

  (1) The PM accumulation amount PMsm calculated in the immediately preceding step S152 has reached the regeneration required accumulation amount PMeg. In the present embodiment, the regeneration required accumulation amount PMeg is set such that EGPMsulf (PMeg)> EGSULF with respect to the emission required accumulation amount EGSULF.

(2) The upstream and downstream differential pressure ΔP detected by the differential pressure sensor 50 is greater than the PM regeneration reference differential pressure ΔPeg.
If neither (1) nor (2) is satisfied (“no” in S156), the process is temporarily terminated. If either (1) or (2) is satisfied, PM regeneration is performed. The request is set to ON (S158). When the PM regeneration request is turned ON, the ECU 70 adds fuel from the addition valve 68, so that the temperature raising process is continued until the PM accumulation amount PMsm calculated in step S152 becomes 0 g. As a result, all PM deposited on the filter 38a is oxidized and purified. That is, as described in step S112 of the sulfate release control process (FIG. 2), the fuel addition is combusted in the NOx storage reduction catalyst 36a and the filter 38a by repeatedly performing fuel addition from the addition valve 68 into the exhaust. Heat is generated and PM is purified by oxidation. At this time, since the temperature of the oxidation catalyst 40a is also raised, if the sulfate is deposited on the oxidation catalyst 40a, all of the accumulated sulfate is released in the process of releasing the PM accumulation amount PMsm. .

  In the subsequent control cycle, the PM regeneration process is continued until the PM accumulation amount PMsm is calculated to be 0 g in step S152, and the state determined as “no” in step S154 is continued. If the PM accumulation amount PMsm = 0 g, the PM regeneration process is stopped, so that “yes” is determined in step S154.

  An example of the control of the present embodiment is shown in the timing charts of FIGS. In the example of FIG. 4, the PM deposition amount PMsm satisfies PMsm ≧ PMeg before the sulfate deposition amount SULFsm satisfies SULFsm ≧ EGSULF. Accordingly, the normal temperature regeneration process is executed, and the temperature increase process (t1 to t2, t3 to t4) until the PM accumulation amount PMsm becomes 0 (t2, t4) from the state (t1, t3) of the regeneration required accumulation amount PMeg. Is made. As a result, all the sulfate deposited on the oxidation catalyst 40a is also released during the normal PM regeneration process.

  In the example of FIG. 5, before the PM deposition amount PMsm becomes PMsm ≧ PMeg (= PM3), the sulfate deposition amount SULFsm satisfies SULFsm ≧ EGSULF (t11). The degree of the temperature raising process for purifying the total amount of PM deposition amount PMsm (= PM3) at this time is higher than the degree of the temperature raising process capable of releasing all the sulfate accumulation amount SULFsm (= EGSULF) at this time. Therefore, in order to release the sulfate, the PM regeneration process for purifying the PM deposition amount PMsm (= PM3) at this time is executed until the PM deposition amount PMsm = PM3 is changed from the state (t11) to 0 (t12). A temperature raising process (t11 to t12) is performed. When all the PM is purified by this PM regeneration treatment, all the sulfate accumulated on the oxidation catalyst 40a is also released.

  After this, as in the case of FIG. 4, the PM deposition amount PMsm satisfies PMsm ≧ PMeg before the sulfate deposition amount SULFsm becomes SULFsm ≧ EGSULF (= SULF3). Therefore, the normal PM regeneration process is executed, and the temperature raising process (t13 to t14) is performed until the PM accumulation amount PMsm becomes 0 (t14) from the regeneration required accumulation amount PMeg state (t13). As a result, all the sulfate deposited on the oxidation catalyst 40a is also released by the normal PM regeneration process.

  In the example of FIG. 6, before the PM deposition amount PMsm becomes PMsm ≧ PMeg (= PM4), the sulfate deposition amount SULFsm satisfies SULFsm ≧ EGSULF (t21). At this time, the degree of the temperature raising process for purifying the total amount of PM deposition amount PMsm (= PM4) is lower than the degree of the temperature raising process capable of releasing all the sulfate accumulation amount SULFsm (= EGSULF) at this time. Therefore, the sulfate release process (t21 to t22) corresponding to the extent that the sulfate accumulation amount SULFsm (= EGSULF) at this time can be purified is executed. In the middle of the release of sulfate, PM becomes 0 from the state where the PM deposition amount PMsm = PM4. Then, after all the PM has been purified, when all the sulfate accumulated on the oxidation catalyst 40a is released, the sulfate release process ends (t22).

  After this, as in the case of FIG. 4, before the sulfate accumulation amount SULFsm becomes SULFsm ≧ EGSULF (= SULF4), the PM accumulation amount PMsm satisfies PMsm ≧ PMeg. Accordingly, the normal PM regeneration process is executed, and the temperature raising process (t23 to t24) is performed until the PM deposition amount PMsm becomes 0 (t24) from the state (t23) of the regeneration required deposition amount PMeg. Through this normal PM regeneration process, all of the sulfate deposited on the oxidation catalyst 40a is also released.

  In the configuration described above, the relationship with the claims corresponds to the ECU 70 corresponding to the exhaust purification control means, the exhaust system temperature raising means, the particulate matter purification means, and the sulfur compound releasing means. The process of adding fuel from the addition valve 68 when the PM regeneration request is turned on or the sulfate release request is turned on is the process as the exhaust system temperature raising means, and the PM regeneration control process (FIG. 3) is the process as the particulate matter purification means. The release control process (FIG. 2) corresponds to a process as a sulfur compound releasing means.

According to the first embodiment described above, the following effects can be obtained.
(I). In the sulfate release control process (FIG. 2), when the degree of the temperature raising process capable of purifying all the PM deposit amount PMsm is equal to or more than the degree of the temperature rise process capable of releasing all the sulfate deposit amount SULFsm (“no” in S108). "), A temperature raising process for purifying the PM deposit amount PMsm for the release of sulfate is performed. This realizes complete release of sulfate simultaneously with complete purification of PM.

  As described above, since the control is performed in consideration of the sulfate release during the temperature increase process of PM regeneration, the same state of the actual sulfate deposition amount and the sulfate deposition amount SULFsm assumed in the sulfate release processing can be maintained. Therefore, an excessive temperature increase process during the sulfate release process is prevented as compared with the case where the temperature increase process is performed independently in the sulfate release process and the PM regeneration process.

  In this way, it is possible to save the temperature rising energy, here the amount of fuel added from the addition valve 68, as compared with the case where the temperature rising process is independent of the sulfate release process and the PM regeneration process. The fuel consumption can be improved.

  (B). Further, in the sulfate release control process (FIG. 2), when the degree of the temperature raising process that can purify the PM deposit amount PMsm is not the same as the temperature rise process that can release all the sulfate deposit amount SULFsm (“ yes "), since the sulfate release process can be performed, all the sulfate can be reliably released. Therefore, since the sulfate can be discharged within a low concentration without causing excessive accumulation of sulfate, white smoke or the like is not generated.

[Embodiment 2]
In the present embodiment, unlike the first embodiment, the regeneration required deposition amount PMeg is set to have a relationship of EGPMsulf (PMeg) <EGSULF with respect to the release required deposition amount EGSULF. Therefore, the sulfate release control process of FIG. 7 is executed instead of FIG. 2 of the first embodiment, and the PM regeneration control process of FIG. 8 is executed instead of FIG.

  Steps S202, S204, S206, S210, and S214 constituting all the processes of the sulfate release control process (FIG. 7) are the same processes as steps S102, S104, S106, S110, and S114 of FIG. In FIG. 2, if “yes” is determined in step S <b> 106, the evaluation of expression 2 is executed in step S <b> 108, but the evaluation of expression 2 is not executed in the present embodiment. That is, if “yes” is determined in step S206, the sulfate release request for releasing the sulfate accumulation amount SULFsm is immediately set to ON in the process of step S210. Therefore, there is no PM regeneration request ON setting for purifying the current PM accumulation amount PMsm for the release of sulfate.

  In the PM regeneration control process (FIG. 8), steps S252, S256, and S258 are the same processes as steps S152, S156, and S158 of FIG. The difference is that step S254 determines not only step S258 but also the temperature raising process by step S260 as a temperature raising process for PM regeneration (purification). Furthermore, when it is determined in step S256 that the PM regeneration condition is satisfied, the expression 4 is evaluated in step S257.

[Formula 4] EGPMsulf (PMsm)> SULFsm
This formula 4 has a reverse relationship to the formula 2.
When Expression 4 is satisfied (“yes” in S257), that is, even if the temperature increasing process for releasing all the sulfate accumulated in the oxidation catalyst 40a is executed, the PM accumulation amount PMsm of the filter 38a cannot be completely purified. In this case, a PM regeneration request for purifying the current PM accumulation amount PMsm is set to ON (S258).

  By setting the PM regeneration request ON corresponding to this PM accumulation amount PMsm, the ECU 70 repeatedly performs fuel addition from the addition valve 68 into the exhaust, whereby the added fuel burns in the NOx storage reduction catalyst 36a and the filter 38a, and the filter The temperature raising process for 38a is executed. The degree of the temperature raising process, here, the high temperature and the temperature raising period are controlled by the ECU 70 so that the PM deposition amount PMsm is completely purified. All sulfate accumulated on the oxidation catalyst 40a during this temperature raising process is released.

  If Equation 4 is not satisfied (“no” in S257), step S260 is executed. That is, when the temperature increasing process for releasing all the sulfate accumulated on the oxidation catalyst 40a is performed, if the PM accumulated on the filter 38a can be purified at the same time, the current sulfate accumulation amount SULFsm is used for PM regeneration. The sulfate release request to be released is set to ON (S260).

  By the ON setting of the sulfate release request corresponding to the sulfate accumulation amount SULFsm, the ECU 70 repeatedly adds fuel into the exhaust from the addition valve 68, whereby the added fuel burns in the NOx storage reduction catalyst 36a and the filter 38a to generate heat. PM is purified. Then, along with this PM purification, the exhaust gas is heated up and the oxidation catalyst 40a is heated to a temperature at which sulfate can be released. The degree of the temperature raising process is controlled so that the sulfate accumulation amount SULFsm is completely discharged from the oxidation catalyst 40a. The degree of the temperature raising process is a temperature raising process capable of purifying the PM accumulation amount PMsm at the same time. Therefore, the total amount of PM deposition amount PMsm can be completely purified.

  An example of the control of the present embodiment is shown in the timing charts of FIGS. In the example of FIG. 9, the sulfate accumulation amount SULFsm satisfies SULFsm ≧ EGSULF before the PM accumulation amount PMsm becomes PMsm ≧ PMeg. Therefore, the normal sulfate release process is executed, and the temperature increase process (t31 to t32) is performed until the actual accumulation amount becomes 0 (t32, t34) from the state (t31, t33) of the sulfate accumulation amount SULFsm to the release required deposition amount EGSLF. , T33 to t34). As a result, all PM deposited on the filter 38a is purified during the normal sulfate release process.

  In the example of FIG. 10, the PM accumulation amount PMsm satisfies PMsm ≧ PMeg (t41) before the sulfate accumulation amount SULFsm becomes SULFsm ≧ EGSULF (= SULF13). The degree of the temperature raising process for releasing the total amount of the sulfate accumulation amount SULFsm (= SULF13) at this time is higher than the degree of the temperature raising treatment that can oxidize and purify all the PM accumulation amount PMsm (= PMeg) at this time. Is also expensive. Accordingly, the sulfate release process for releasing the sulfate accumulation amount SULFsm (= SULF13) at this time is executed, and the temperature raising process is performed until the actual accumulation amount becomes 0 (t42) from the state (t41) of the sulfate accumulation amount SULFsm = SULF13. (T41 to t42) are performed. As a result, when all of the sulfate deposited by the sulfate release treatment is released, all of the PM deposited on the filter 38a is purified.

  After this, as in the case of FIG. 9, before the PM accumulation amount PMsm becomes PMsm ≧ PMeg (= PM13), the sulfate accumulation amount SULFsm becomes SULFsm ≧ EGSULF (t43). Therefore, the normal sulfate release process is executed, and the temperature increase process (t43 to t44) is performed from the state (t43) where the sulfate accumulation amount SULFsm is the release required accumulation amount EGSULF until the actual accumulation amount becomes 0 (t44). . During this normal sulfate release process, all PM deposited on the filter 38a is purified.

  In the example of FIG. 11, the PM accumulation amount PMsm satisfies PMsm ≧ PMeg (t51) before the sulfate accumulation amount SULFsm becomes SULFsm ≧ EGSULF (= SULF14). At this time, the degree of the temperature raising process for releasing the total amount of the sulfate accumulation amount SULFsm (= SULF14) is lower than the degree of the temperature raising process that can purify the PM accumulation amount PMsm (= PMeg) at this time. Therefore, the PM regeneration process (t51 to t52) corresponding to the extent that the PM accumulation amount PMsm (= PMeg) at this time can be purified is executed. In the middle of this PM regeneration process, the actual value of sulfate becomes 0 from the state of the sulfate accumulation amount SULFsm = SULF14. Then, after all the sulfate has been released, the PM regeneration process ends when all the PM deposited on the filter 38a is purified (t52).

  After this, as in the case of FIG. 9, before the PM deposition amount PMsm becomes PMsm ≧ PMeg (= PM14), the sulfate deposition amount SULFsm satisfies SULFsm ≧ EGSULF. Accordingly, the normal sulfate release process is executed, and the temperature increase process (t53 to t54) is performed until the actual value of the sulfate accumulation amount SULFsm becomes 0 (t54) from the state (t53) of the required release accumulation amount EGSULF. As a result, all the PM deposited on the filter 38a is purified by the normal sulfate release process.

  In the configuration described above, the relationship with the claims corresponds to the ECU 70 corresponding to the exhaust purification control means, the exhaust system temperature raising means, the sulfur compound releasing means, and the particulate matter purification means. The process of adding fuel from the addition valve 68 when the PM regeneration request is turned on or the sulfate release request is turned on is the process as the exhaust system temperature raising means, and the PM regeneration control process (FIG. 8) is the process as the particulate matter purification means. The release control process (FIG. 7) corresponds to a process as a sulfur compound releasing means.

According to the second embodiment described above, the following effects can be obtained.
(I). In the PM regeneration control process (FIG. 8), when the degree of the temperature raising process that can release all the sulfate accumulation amount SULFsm is equal to or more than the degree of the temperature raising process that can simultaneously purify the PM accumulation amount PMsm (“no” in S257). )), A temperature increasing process for releasing the sulfate accumulation amount SULFsm is performed for PM purification. This realizes complete purification of PM simultaneously with complete release of sulfate.

  As described above, the control is performed in consideration of the PM purification at the time of the temperature increase process of the sulfate release, so that the same state of the actual PM deposition amount and the PM deposition amount PMsm assumed in the PM regeneration process can be maintained. Therefore, an excessive temperature increase process during the PM regeneration process is prevented as compared with the case where the temperature increase process is independent between the sulfate release process and the PM regeneration process.

  In this way, it is possible to save the temperature rising energy, here the amount of fuel added from the addition valve 68, as compared with the case where the temperature rising process is independent of the sulfate release process and the PM regeneration process. The fuel consumption can be improved.

  (B). Furthermore, in the PM regeneration control process (FIG. 8), when the temperature increase process that can release all the sulfate accumulation amount SULFsm is not the same as the temperature increase process that can purify the PM accumulation amount PMsm at the same time ( In S257, “yes”), the PM regeneration process can be executed, so that all PM can be reliably purified. Therefore, since excessive accumulation of PM does not occur, the engine back pressure can be reduced at an early stage, so that good fuel consumption can be maintained.

[Embodiment 3]
In the present embodiment, both the case where the expression 2 is not satisfied when the sulfate release condition is satisfied and the case where the expression 4 is not satisfied when the PM regeneration condition is satisfied are examples. Therefore, the PM regeneration control process of FIG. 8 is executed instead of FIG. 3 of the first embodiment, and the sulfate release control process of FIG. 2 is executed as it is. Each processing content is as described in the first and second embodiments.

  With such a combination of processes, the relationship between the regeneration required deposition amount PMeg and the release required deposition amount EGSULF can be dealt with even if EGPMsulf (PMeg)> EGSULF or EGPMsulf (PMeg) <EGSULF. Even if EGPMsulf (PMeg)> EGSULF, even if it is necessary to execute PM regeneration before PMsm ≧ PMeg for the convenience of engine control, the sulfate can be completely released at the same time. .

  In the configuration described above, the relationship with the claims corresponds to the ECU 70 corresponding to the exhaust purification control means, the exhaust system temperature raising means, the sulfur compound releasing means, and the particulate matter purification means. The process of adding fuel from the addition valve 68 when the PM regeneration request is turned on or the sulfate release request is turned on is the process as the exhaust system temperature raising means, and the PM regeneration control process (FIG. 8) is the process as the particulate matter purification means. The release control process (FIG. 2) corresponds to a process as a sulfur compound releasing means.

According to the third embodiment described above, the following effects can be obtained.
(I). The effects of the first and second embodiments are produced.
[Other embodiments]
(A). In the above-described embodiment, the exhaust purification unit is configured as a combination of the NOx storage reduction catalyst 36a, the filter 38a, and the oxidation catalyst 40a. However, the exhaust purification unit includes only one filter that does not include the NOx purification catalyst. But it ’s okay. That is, even if the present invention is applied to a diesel particulate filter carrying a catalyst that oxidizes collected PM, which is called “DPF”, each effect can be obtained by controlling as in the above embodiments. Can be made.

  The filter 38a used in each of the above embodiments is referred to as “DPNR”, and includes a NOx purification catalyst (in this case, a NOx storage reduction catalyst), and a catalyst that oxidizes the collected PM. Is a diesel particulate filter carrying

  (B). In the temperature raising process, the fuel addition from the addition valve 68 alone or the after injection that is the fuel injection into the combustion chamber 4 in the expansion stroke or the exhaust stroke by the fuel injection valve 58 is added, but the after injection alone may be used.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic structure explanatory drawing of the vehicle diesel engine and control system of Embodiment 1. FIG. 4 is a flowchart of the sulfate release control process according to the first embodiment. 5 is a flowchart of PM regeneration control processing according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 4 is a timing chart illustrating an example of processing according to the first embodiment. 10 is a flowchart of a sulfate release control process according to the second embodiment. 10 is a flowchart of PM regeneration control processing according to the second embodiment. 9 is a timing chart illustrating an example of processing according to the second embodiment. 9 is a timing chart illustrating an example of processing according to the second embodiment. 9 is a timing chart illustrating an example of processing according to the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Diesel engine, 4 ... Combustion chamber, 6 ... Intake valve, 8 ... Intake port, 13 ... Intake passage, 14 ... Intercooler, 16 ... Exhaust turbocharger, 16a ... Compressor, 16b ... Exhaust turbine, 18 ... Air cleaner, 20 ... EGR path, 20a ... EGR gas supply port, 20b ... EGR gas intake port, 22 ... throttle valve, 22a ... throttle opening sensor, 22b ... motor, 24 ... intake air amount sensor, 26 ... intake air temperature sensor, 28 ... exhaust Valve, 30 ... Exhaust port, 32 ... Exhaust manifold, 34 ... Exhaust passage, 36 ... First catalytic converter, 36a ... NOx occlusion reduction catalyst, 38 ... Second catalytic converter, 38a ... Filter, 40 ... Third catalytic converter, 40a ... oxidation catalyst, 44 ... first exhaust temperature sensor, 46 ... second exhaust temperature sensor, 48 ... air-fuel ratio sensor, 50 ... differential pressure Sensor, 52 ... EGR catalyst, 54 ... EGR cooler, 56 ... EGR valve, 58 ... fuel injection valve, 58a ... fuel supply pipe, 60 ... common rail, 62 ... fuel pump, 64 ... fuel pressure sensor, 66 ... fuel supply pipe, 68 ... addition valve, 70 ... ECU, 72 ... accelerator pedal, 74 ... accelerator opening sensor, 76 ... cooling water temperature sensor, 78 ... crankshaft, 80 ... engine speed sensor, 82 ... cylinder discrimination sensor.

Claims (7)

Particulate matter purification function that filters particulate matter in the exhaust discharged from the combustion chamber of the internal combustion engine and oxidizes the deposited particulate matter by heating treatment, and oxidizes unburned components in the exhaust An internal combustion engine exhaust purification device that realizes an oxidation catalyst function that can be purified by an exhaust purification unit consisting of a single part or a plurality of parts,
When the sulfur compound deposition amount in the exhaust purification unit reaches the required release deposition amount and the execution condition of the sulfur compound release processing for releasing the sulfur compound to the exhaust downstream side by the temperature raising processing is satisfied , the exhaust purification unit If the degree of the temperature raising process necessary for purifying the particulate matter deposited on the exhaust gas is greater than the degree of the temperature raising process required for the sulfur compound releasing process, the particles deposited on the exhaust purification unit An exhaust gas purification apparatus for an internal combustion engine, comprising exhaust gas purification control means for performing a temperature raising process for purifying the particulate matter. The exhaust purification control means according to claim 1,
An exhaust system temperature raising means for performing the temperature raising process by one or both of fuel addition to the exhaust gas purification unit and high temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine;
The particulate matter for controlling the exhaust system temperature raising means to purify the particulate matter deposited in the exhaust purification unit when the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount. Substance purification means;
When the amount of sulfur compound deposited in the exhaust purification unit reaches the required amount of release, the amount of sulfur compound deposited is not released at the degree of the temperature raising process that purifies the amount of particulate matter currently deposited. If it is determined to be sufficient, the exhaust system temperature raising means is controlled to execute a temperature raising process for releasing the total amount of the sulfur compound deposit, and if not determined to be insufficient, the particulate matter deposit amount is set to the total amount. A sulfur compound releasing means for controlling the exhaust system temperature raising means so as to execute a temperature raising process to be purified;
An exhaust purification system for an internal combustion engine, comprising: Particulate matter purification function that filters particulate matter in the exhaust discharged from the combustion chamber of the internal combustion engine and oxidizes the deposited particulate matter by heating treatment, and oxidizes unburned components in the exhaust An internal combustion engine exhaust purification device that realizes an oxidation catalyst function that can be purified by an exhaust purification unit consisting of a single part or a plurality of parts,
When the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount and the execution condition of the particulate matter purification processing for purifying the particulate matter by the temperature rising process is established , the exhaust purification unit When the degree of the temperature raising process required for releasing the deposited sulfur compound is equal to or higher than the degree of the temperature raising process required for the particulate matter purification process, the sulfur compound deposited in the exhaust purification unit An exhaust purification device for an internal combustion engine, comprising exhaust purification control means for executing a temperature raising process for releasing the exhaust gas downstream of the exhaust. The exhaust purification control means according to claim 3,
An exhaust system temperature raising means for performing the temperature raising process by one or both of fuel addition to the exhaust gas purification unit and high temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine;
Sulfur compound releasing means for controlling the exhaust system temperature raising means in order to release the sulfur compound accumulated in the exhaust purification unit when the sulfur compound deposition amount in the exhaust purification unit reaches the required discharge amount When,
When the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount, the particulate matter deposition amount is completely purified at the degree of the temperature raising process that releases the entire sulfur compound deposition amount at the present time. If determined to be insufficient, the exhaust system temperature raising means is controlled to execute a temperature raising process for purifying the total amount of particulate matter deposited, and if not judged to be insufficient, the amount of sulfur compound deposited is reduced. Particulate matter purification means for controlling the exhaust system temperature raising means so as to perform a temperature raising process for releasing the whole amount;
An exhaust purification system for an internal combustion engine, comprising: Particulate matter purification function that filters particulate matter in the exhaust discharged from the combustion chamber of the internal combustion engine and oxidizes the deposited particulate matter by heating treatment, and oxidizes unburned components in the exhaust An internal combustion engine exhaust purification device that realizes an oxidation catalyst function that can be purified by an exhaust purification unit consisting of a single part or a plurality of parts,
When the sulfur compound deposition amount in the exhaust purification unit reaches the required release deposition amount and the execution condition of the sulfur compound release processing for releasing the sulfur compound to the exhaust downstream side by the temperature raising processing is satisfied , the exhaust purification unit When the degree of the temperature raising process necessary for the purification of the particulate matter deposited on the exhaust gas is greater than the degree of the temperature raising process required for the sulfur compound releasing treatment, the particulate matter deposited on the exhaust purification unit Conditions for purifying the particulate matter by the temperature raising process when the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount Is established, the degree of the temperature raising process necessary for releasing the sulfur compound accumulated in the exhaust purification unit is greater than the degree of the temperature raising process required in the particulate matter purification process. Sulfur compounds deposited in the exhaust purification section Internal combustion engine exhaust gas purification apparatus characterized by comprising an exhaust gas purification control unit for performing the Atsushi Nobori process of releasing the exhaust gas downstream side. The exhaust purification control means according to claim 5,
An exhaust system temperature raising means for performing the temperature raising process by one or both of fuel addition to the exhaust gas purification unit and high temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine;
When the particulate matter deposition amount in the exhaust purification unit reaches the regeneration required deposition amount, the particulate matter deposition is performed at the extent of the temperature raising process that releases the entire sulfur compound deposition amount in the exhaust purification unit at the present time. If it is determined that the total amount purification of the amount is insufficient, the exhaust system temperature raising means is controlled to execute the temperature raising process for purifying the particulate matter accumulation amount in its entirety. Particulate matter purification means for controlling the exhaust system temperature raising means so as to perform a temperature raising process for releasing the total amount of sulfur compound deposits;
When the sulfur compound deposition amount in the exhaust purification unit reaches the emission request deposition amount, the sulfur compound deposition amount is at the level of the temperature raising process that purifies the entire particulate matter deposition amount in the exhaust purification unit at the present time. If it is determined that the total amount release of the exhaust system is insufficient, the exhaust system temperature raising means is controlled to execute the temperature raising process for releasing the total amount of the sulfur compound deposit, and if it is not judged insufficient, the particulate A sulfur compound releasing means for controlling the exhaust system temperature raising means so as to perform a temperature raising process for purifying the total amount of material deposition;
An exhaust purification system for an internal combustion engine, comprising: The exhaust gas purification unit according to any one of claims 1 to 6, wherein the exhaust gas purification unit carries an exhaust gas purification part that filters a particulate matter and supports a NOx purification catalyst and a catalyst that oxidizes and purifies the particulate material, and the exhaust gas purification unit. An internal combustion engine exhaust comprising at least two parts: an exhaust purification part provided on the exhaust downstream side with respect to the purification part and carrying an oxidation catalyst that oxidizes and purifies unburned components in the exhaust. Purification equipment.

Images