JP4075724B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

  2. Description of the Related Art Conventionally, as an exhaust gas purification device for an internal combustion engine, an organic solvent soluble (SOF) component (hereinafter referred to as SOF component or SOF) and dry soot that constitute PM (Particulate Iate) (particulate matter) in exhaust gas. There is known a technique for estimating the amount of carbonaceous component (hereinafter referred to as DS component) called (DrySoot) and integrating the amount of each sediment collected by DPF (Diesel Particulate Filter). (See Patent Document 1).

This is because, when it is determined that the operating state of the internal combustion engine is in the SOF collection region, the SOF collection rate is multiplied by the flow rate distribution ratio to obtain an increment of the SOF collection rate, and the SOF deposition amount thus far In addition, the SOF deposition amount is obtained.
JP 7-34857 A

  By the way, the emission amount of the SOF component and the DS component constituting the PM varies depending on the operation state and the fuel property. In the low / medium load operation state, the lower the cetane number of the fuel, the larger the emission amount of the SOF component. As the value increases, the emission amount of the SOF component decreases and the emission amount of the DS component increases (see FIG. 6A). Further, in a high-load operating state, there is almost no SOF component emission, and the emission characteristic is such that the DS component emission amount increases as the cetane number of the fuel increases (see FIG. 6B).

  However, in the above prior art, the fuel properties are not taken into consideration, and an error occurs in the estimation of the accumulated amounts of the SOF component and the DS component collected in the DPF.

  Therefore, the present invention has been made in view of the above problems, and the regeneration timing of the DPF can be controlled in accordance with the discharge characteristics of the carbonaceous (DS) component and the organic solvent soluble (SOF) component that change depending on the fuel properties. An object of the present invention is to provide an exhaust emission control device for an internal combustion engine.

The present invention relates to a particulate collection filter provided in an exhaust passage, and a regeneration means for regenerating the collection filter by burning and removing particulates that are attached to the particulate collection filter and accumulated in a predetermined amount or more on the collection filter. A fuel property detecting means for detecting the cetane number of the fuel being used, an operating state detecting means for detecting the engine operating state, and the engine operating state detected by the operating state detecting means is low / medium load In this case, the amount of the organic solvent soluble component discharged from the engine per unit time for the fuel is increased in accordance with the decrease in the cetane number detected by the fuel property detecting means and detected by the fuel property detecting means. As the cetane number increases, the amount of carbonaceous components emitted from the engine per unit time for fuel is increased to increase the amount of carbon When the engine operating state detected by the operating state detecting means is a high load while calculating the accumulated amount of particulates collected and accumulated in the collecting filter together with the components, the fuel is discharged from the engine per unit time for fuel. Deposition in which only the amount of carbonaceous component produced is increased according to the increase in cetane number detected by the fuel property detection means, and the amount of particulates collected and deposited on the particulate collection filter is calculated together with the components An amount calculating means; and a regeneration operation control means for controlling the regeneration operation of the regeneration means based on the accumulation amount and components computed by the accumulation amount computing means.

Therefore, in the present invention, the fuel property detecting means for detecting the cetane number of the fuel being used is provided, and when the engine operating state is low / medium load, the cetane number detected by the fuel property detecting means is detected. The amount of organic solvent soluble component discharged from the engine per unit time with respect to the fuel is increased in accordance with the decrease, and the fuel is discharged from the engine per unit time with respect to the increase in the cetane number detected by the fuel property detecting means. The amount of particulate matter collected and deposited on the particulate collection filter is calculated together with the component while increasing the amount of carbonaceous component produced, while the engine operating state detected by the operating state detecting means is high load In this case, only the amount of carbonaceous components discharged from the engine per unit time for the fuel is the set value detected by the fuel property detecting means. The trapped in particulate collection filter calculates the amount of deposition particulate with components deposited is increased in accordance with the value of the rise, to control the playback operation of the DPF on the basis of the calculated deposit amount and components In addition, it is possible to accurately estimate the amount of SOF component and DS component that are collected in the DPF, to regenerate the DPF at an appropriate timing, and to extend its life.

  Hereinafter, an exhaust emission control device for an internal combustion engine of the present invention will be described based on each embodiment.

(First embodiment)
FIG. 1 is a configuration diagram of an engine system to which an exhaust gas purification apparatus for an internal combustion engine according to the present invention is applied. The diesel engine uses diesel oil as fuel as an example.

  In FIG. 1, 1 indicates a diesel engine (hereinafter simply referred to as an engine), and 3 indicates an exhaust passage of the engine 1.

  An exhaust outlet passage 3a constituting an upstream portion of the exhaust passage 3 of the engine 1 is connected to a turbine 3b of a supercharger, and a downstream of the particulate collection filter 21 (hereinafter referred to as an exhaust aftertreatment device) as an exhaust aftertreatment device. A casing 20 in which the DPF is housed is disposed. The DPF 21 carries an oxidation catalyst (noble metal) and has a function of oxidizing the inflowing exhaust components (HC, CO). An air-fuel ratio sensor 37 serving as an actual air-fuel ratio detection unit is provided at the inlet of the casing 20. The air-fuel ratio sensor 37 detects the oxygen concentration in the exhaust gas using, for example, an oxygen ion conductive solid electrolyte, and obtains the air-fuel ratio from the oxygen concentration. For exhaust purification, NOx in exhaust flowing in when the exhaust air-fuel ratio is lean is trapped downstream or upstream of the DPF in the exhaust passage 3, and the trapped NOx is removed and purified when the exhaust air-fuel ratio is rich. A NOx trap catalyst may be arranged. The NOx trap catalyst carries an oxidation catalyst (noble metal) and has a function of oxidizing the inflowing exhaust components (HC, CO). Alternatively, the DPF 21 may be configured integrally with a NOx trap catalyst.

  Between the intake collector 2c of the intake passage 2 and the exhaust outlet passage 3a, an EGR passage 4 for recirculating a part of the exhaust is provided, and the opening degree is continuously controlled by a stepping motor. A possible EGR valve 5 is interposed.

  The intake passage 2 is provided with an air cleaner 2a at an upstream position, and an airflower 7 serving as intake air amount detection means is provided on the outlet side thereof. A turbocharger compressor 2b is arranged downstream of the air flow overnight 7, and an intake throttle valve that is opened and closed by an actuator (for example, a stepping motor type) between the compressor 2b and the intake collector 2c. 6 is interposed.

  The fuel supply system of the engine 1 includes a fuel tank 60 that stores diesel oil as diesel fuel, a fuel supply passage 16 that supplies fuel to the fuel injection device 10 of the engine 1, and a fuel supply device 16 of the engine 1. And a fuel return passage 19 for returning the return fuel (spill fuel) to the fuel tank 60.

  The fuel injection device 10 of the engine 1 is a known common rail type fuel injection device, and generally includes a supply pump 11, a common rail (accumulation chamber) 14, and a fuel injection valve 15 provided for each cylinder. After the fuel pressurized by the supply pump 11 is temporarily stored in the common rail 14 via the fuel supply passage 12, the high-pressure fuel in the common rail 14 is distributed to the fuel injection valves 15 of each cylinder.

  The common rail 14 is provided with a pressure sensor 34 and a temperature sensor 35 in order to detect the pressure and temperature of the fuel in the common rail 14. Further, in order to control the fuel pressure in the common rail 14, the portion of the fuel discharged from the supply pump 11 is returned to the fuel supply passage 16 via the overflow passage 17 having a one-way valve 18. . Specifically, a pressure control valve 13 that changes the flow passage area of the overflow passage 17 is provided, and the pressure control valve 13 changes the flow passage area of the overflow passage 17 in accordance with a duty signal from the engine control unit 30. Thereby, the substantial fuel discharge amount from the supply pump 11 to the common rail 14 is adjusted, and the fuel pressure in the common rail 14 is controlled.

  The fuel injection valve 15 is an electronic injection valve that is opened and closed by an ON-OFF signal from the engine control unit 30, and injects fuel into the combustion chamber by the ON signal and stops injection by the OFF signal. The fuel injection amount increases as the period of the ON signal applied to the fuel injection valve 15 increases, and the fuel injection amount increases as the fuel pressure of the common rail 14 increases.

  The engine control unit 30 includes a signal (Qa) from the air flow meter 7 for detecting the intake air amount, a signal from the water temperature sensor 31 (water temperature Tw), and a signal from the crank angle sensor 32 for crank angle detection (the basis of the engine speed Ne) Crank angle signal), a cylinder discrimination crank angle sensor 33 signal (cylinder discrimination signal Cy1), a pressure sensor 34 signal for detecting fuel pressure in the common rail 14 (common rail pressure PCR), and a temperature sensor 35 for detecting fuel temperature. A signal (fuel temperature TF), a signal of an accelerator opening sensor 36 (accelerator opening (load) L) for detecting an amount of depression of an accelerator pedal corresponding to a load, a signal (O2) of an air-fuel ratio sensor 37 (exhaust air-fuel ratio ( Hereinafter, it is referred to as exhaust λ, and the numerical value is expressed by the excess air ratio)), and the DPF temperature for detecting the temperature of the DPF 21 Signal of the sensor 38 (DPF temperature Td), are input respectively.

  The control unit 30 reads the water temperature Tw, the engine speed Ne, the cylinder discrimination signal Cyl, the common rail pressure PCR, the signal Qa of the air flow meter 7, the fuel temperature TF, the accelerator opening L, and the air-fuel ratio sensor signal O2, respectively. The target reference pressure PCRO of the common rail 14 is obtained by searching a predetermined map stored in advance in the ROM of the control unit 30 using the rotation speed Ne and the load L as parameters so that the target reference pressure PCRO can be obtained. The common rail pressure control is performed by executing the feedback control of the pressure control valve 13.

  The control unit 30 also controls the fuel injection amount and the injection timing of the main injection by the fuel injection valve 15 and the post injection after the main injection (expansion stroke or exhaust stroke) under predetermined operating conditions based on these input signals. A fuel injection command signal to the fuel injection valve 15, an opening command signal to the intake throttle valve 6, an opening command signal to the EGR valve 5, etc. are output.

  The control unit 30 further performs exhaust gas purification control for purification of PM collected and accumulated in the DPF 21 (DPF regeneration).

  2 to 4 and 8 are flowcharts of the exhaust purification control by the DPF 21 that is periodically executed by the control unit 30. FIG. First, a description will be given along the flow of FIG. Note that when a return is made in the flow of FIG. 8, the flow returns to the start of the flow of FIG.

  In step S1, various sensor signals are read, and the engine speed Ne, the accelerator opening L, the DPF temperature Td, and the signal O2 (exhaust λ) of the air-fuel ratio sensor 37 are detected. Further, a fuel injection amount (main injection amount) Q calculated from a map using the engine speed Ne and the accelerator opening L as parameters is read. Further, the water temperature Tw, the cylinder discrimination signal Cyl, the common rail pressure PCR, the signal Qa of the air flow meter 7, and the fuel temperature TF are read.

  In step S2, the supplied fuel properties (cetane number, fuel specific gravity) are detected. For example, as shown in Japanese Utility Model Publication No. 3-45181, the fuel property is detected by providing a pendulum that falls due to gravity acting on the weight in the fuel tank and measuring the pendulum fall time that depends on the viscosity. As shown in Japanese Patent Application Laid-Open No. 11-107820, a mechanism is provided to determine the viscosity from the drop time and add a correction based on the detected fuel temperature to determine the cetane number and the like. In addition, there is a means for detecting the ignition timing by the cylinder pressure sensor of the diesel engine, and if the target ignition timing differs from the actual ignition timing due to variations in the fuel cetane number, etc., the target ignition timing target ignition timing The fuel property such as the cetane number may be determined based on the difference with respect to the time.

  Here, focusing on the fact that fuel properties such as cetane number correlate with fuel density, that is, specific gravity, the cetane number is determined based on the specific gravity detected by the specific gravity detecting means for detecting the specific gravity of the fuel being used. , Octane number, evaporability, calorific value, aromatic hydrocarbon content, at least one fuel property is detected. The fuel property determination method will be described based on a fuel property determination flowchart of FIG. 3 described later.

  In step S3, the PM deposition amount WPM collected and deposited in the DPF 21 is calculated. The PM accumulation amount is calculated by detecting the exhaust pressure on the DPF inlet side with an exhaust pressure sensor or the like, and comparing the PM accumulation amount with the reference exhaust pressure in the current operating state (engine speed Ne, fuel injection amount Q). Although it may be estimated, here, the calculation is performed by the PM accumulation amount calculating means of FIGS.

  In step S4, it is determined whether or not the reg1 flag indicating that the DPF regeneration mode is being set. If the reg1 flag is not set (reg1 flag = 0), the process proceeds to step S5. If the reg1 flag is set (reg1 flag = 1), the process proceeds to the DPF regeneration mode control shown in FIG. .

  In step S5, it is determined whether or not the PM accumulation amount of the DPF 21 calculated in step S3 is less than a predetermined amount PM1 that is the DPF regeneration timing. If it is determined that the PM accumulation amount exceeds the predetermined amount PM1 indicating the DPF regeneration timing (PM accumulation amount ≧ PM1), the process proceeds to step S9, and the Reg1 flag is set to 1 in step S9 to issue a DPF regeneration request. This processing is terminated.

  In step S6, the SOF deposition amount WSOF of the DPF 21 is calculated. The SOF deposition amount WSOF may be newly calculated, but here, the WSOF calculated in step S3 is read.

  In step S7, from the exhaust gas temperature history, the engine operation history, or the temperature Td history of the DPF temperature sensor 38, the temperature of the DPF 21 is continuously higher than the predetermined temperature from the previous DPF regeneration or SOF separation for a predetermined time. If so, WSOF = 0. Since the SOF component is volatile unburned HC, it is burned and released (SOF release) at a relatively low temperature (200 ° C. to 300 ° C.). In this case, the SOF deposition amount WSOF is set to zero. In this case, the predetermined temperature and the predetermined time can be set in advance by trial execution.

  In step S8, it is determined whether or not the SOF deposition amount WSOF of the DPF 21 detected in steps S6 and S7 is less than a predetermined amount SOF1 that is the DPF regeneration timing. If it is determined that the SOF accumulation amount exceeds the predetermined amount SOF1 indicating the DPF regeneration timing (SOF accumulation amount ≧ predetermined amount SOF1), the process proceeds to step S9, the Reg1 flag is set to 1, and the step in the next cycle is performed. Control proceeds to the DPF regeneration mode control of the DPF 21 shown in FIG.

  Next, the details of the fuel property detection control routine in step S2 will be described based on the flowchart of FIG. By this control, the properties of the fuel being used are detected with high accuracy.

  The fuel property detection control routine will be described below. In step S11, based on the signal Qa of the air flow meter 7 that detects the intake air amount, the table data of the predetermined intake air amount Qair stored in advance in the ROM of the control unit 30 is retrieved using the value of the signal Qa as a parameter. To do. Then, the process proceeds to step S12.

  In step S12, the main fuel injection amount (fuel supply amount) Qmain set with the engine speed Ne and the load L as parameters is obtained by searching a predetermined map stored in advance in the ROM of the control unit 30. Then, the process proceeds to step S13.

  Note that the main fuel injection amount (fuel supply amount) Qmain is not the above-described method, but the fuel injection period Mperiod of the fuel injection device set by using the engine speed Ne and the load L as parameters is set to the control unit 30. A search is made for a predetermined map stored in advance in the ROM, and a main fuel injection amount (fuel supply amount) Qmain set with the fuel injection period Mperiod and the common rail pressure PCR as parameters is stored in the ROM of the control unit 30. A predetermined map stored in advance may be searched for.

  In step S13, based on the signal O2 of the air-fuel ratio sensor 37, the table data of the actual air-fuel ratio AFrea1 stored in advance in the ROM of the control unit 30 is retrieved using the value of the signal O2 as a parameter. Then, the process proceeds to step S14.

  In step S14, it is determined whether or not the conditions are suitable for detecting the fuel property.

  For example, in general, an automobile engine is generally provided with an exhaust gas recirculation device including an EGR valve 5 and the like for NOx reduction. Since the fuel ratio shifts to the rich side, it is necessary to correct the exhaust gas recirculation in order to accurately obtain the actual air fuel ratio. Accordingly, since there is a concern that the detection accuracy of the actual air-fuel ratio deteriorates due to the correction, it is desirable to issue the actual air-fuel ratio detection command only in a region where exhaust gas recirculation is stopped.

  If it is not suitable for the detection condition in step S14, the process is terminated without detecting the fuel property. If it is suitable for the detection condition in step S14, the process proceeds to step S15.

  In step S15, the actual fuel supply weight Gmain is obtained based on the intake air flow rate Qair obtained in step S11 and the actual air-fuel ratio AFrea1 obtained in step S13. Specifically, the intake air flow rate Qair is divided by the actual air-fuel ratio AFreal to obtain the actual fuel supply weight Gmain (Gmain = Qair ÷ AFrea1). Then, the actual specific gravity Gfuel is determined based on the determined actual fuel supply weight Gmain and the main fuel injection amount (fuel supply amount) Qmain determined in step S12. Specifically, the actual fuel supply weight Gmain is divided by the main fuel injection amount (fuel supply amount) Qmain to obtain an actual specific gravity Gfue1 (Gfue1 = Gmain ÷ Qmain). Then, the process proceeds to step S16.

  In step S16, the standard specific gravity (reference temperature, for example, specific gravity at a standard temperature of 20 ° C.) Gstd is obtained from the actual specific gravity Gfue1 and the fuel temperature TF. Specifically, a map of the standard specific gravity Gstd stored in advance in the ROM of the control unit 30 is searched using the actual specific gravity Gfuel and the fuel temperature TF as parameters, and a corresponding value is obtained. Then, the process proceeds to step S17.

  In step S17, using the standard specific gravity Gstd as a parameter, the fuel property stored in advance in the ROM of the control unit 30, for example, table data of the cetane number Cnumber is searched.

  Through the above steps, the specific gravity is detected from the intake air amount, the fuel supply amount, and the actual air-fuel ratio, so that the fuel property can be accurately determined by a practical method, and the detected engine is used as the fuel supply amount detection means. By obtaining the fuel injection amount as map data from the rotation speed and the load, the function originally provided in the engine can be used, and the cost is not increased. Further, the actual fuel supply weight is obtained by dividing the intake air flow rate by the actual air-fuel ratio, and the actual specific gravity is obtained by dividing the actual fuel supply weight by the main fuel injection amount (fuel supply amount). The fuel property can be detected with high accuracy and without an increase in cost, and the fuel property is obtained with the standard specific gravity taken into consideration in consideration of the fuel temperature, so that the fuel property can be detected with higher accuracy.

  Next, the details of the control routine for detecting the PM accumulation amount on the DPF in step S3 will be described based on the flowchart of FIG.

  First, in step S31, the dry soot discharge amount Δdry discharged from the engine per unit time for the fuel having the fuel property (for example, cetane number CN) detected in step S2 is obtained using the engine speed and load as parameters. The dry soot is a carbon particle constituting a part of the particulate PM, and the particulate PM is composed of the dry soot and SOF described later. Further, as shown in FIG. 5, the dry soot discharge amount Δdry is obtained from a map stored in advance in the ROM, and the dry soot discharge amount Δdry increases as the engine speed increases and the load torque increases. Become. This map is set for each cetane number CN from the fuel property of the supplied fuel, for example, for fuel with a low cetane number CN to fuel with a high cetane number CN. When the dry soot emission amount Δdry during low / medium load operation of the engine 1 is shown continuously from the low cetane number region to the high cetane number region, the emission amount is low at the low cetane number CN as shown in FIG. As the cetane number CN becomes relatively high, the ignitability of the fuel improves and the ignition delay period is shortened, so that the dry soot emissions gradually increase. It is set to reflect on the map. Similarly, when the dry soot emission amount Δdry during high-load operation of the engine 1 is shown continuously from the low cetane number region to the high cetane number region, as shown in FIG. 6B, the emission amount is low at the low cetane number CN. The amount of dry soot is gradually increased by increasing the ignitability of the fuel as the cetane number CN increases and the ignition delay period is further shortened as the cetane number CN increases. Based on the increasing characteristic, it is set to reflect in the map of each cetane number CN.

  The map of the dry soot discharge amount Δdry is set for each cetane number CN. However, the standard map for the standard cetane number (for example, CN = 60) and the cetane number for the cetane number CN that increases or decreases depending on the supplied fuel. A cetane number correction coefficient map (FIG. 6C) in which the valence correction coefficient is stored is set, and when the dry soot discharge amount Δdry is calculated, the emission amount of the reference map and the cetane number stored in the cetane number correction coefficient map are set. The dry soot discharge amount Δdry may be obtained by multiplying the corresponding coefficient.

  In step S32, the dry soot deposition amount Δdry is multiplied by the filter collection efficiency ηdry and the flow rate distribution ratio α to the corresponding filter member 21 to obtain an increment of the dry soot deposition amount. Add to W1dry.

  Next, in step S33, it is stored in the ROM whether the engine operating state for the fuel of the fuel property (for example, cetane number CN) detected in step S2 is in the SOF collection region or the SOF separation region. The determination is made based on the SOF collection / leaving map in FIG. Here, the SOF is collected more efficiently as the engine operation state is in the low load / low rotation region, and a larger amount of SOF is released as the engine operation state is in the high load / high rotation region. The SOF collection / removal map is set for each cetane number CN from the fuel property of the supplied fuel, for example, from the fuel with a low cetane number CN to the fuel with a high cetane number CN. That is, the SOF collection area and the separation area set in the SOF collection / separation map for each cetane number CN during low / medium load operation of the engine are continuously shown from the low cetane number area to the high cetane number area. As shown in FIG. 6A, low cetane number CN has poor ignitability and a large amount of SOF emissions, and as cetane number CN increases, fuel ignitability improves and SOF emissions decrease. Therefore, based on this characteristic, it is set to reflect in the map for each cetane number CN. Similarly, the SOF collection area and the separation area set in the SOF collection / separation map for each cetane number CN during high load operation of the engine are related to the cetane number CN as shown in FIG. However, since the SOF emission is almost small, the SOF separation area is set to be different for each cetane number CN.

  As for the SOF collection / removal map, a reference map for a standard cetane number (for example, CN = 60) and a cetane number correction coefficient map that stores a cetane number correction coefficient for a cetane number CN that increases or decreases depending on the supplied fuel. (FIG. 6 (C)) is set, and the SOF is calculated by multiplying the emission amount of the reference map by the coefficient corresponding to the cetane number CN stored in the cetane number correction coefficient map at the time of calculating the SOF collection area and the separation area. You may ask for a collection area and a withdrawal area.

  The SOF is a mist-like HC constituting a part of the particulate, and the propagation of combustion differs depending on the content of the SOF, which is a substance that affects the regeneration ability of the DPF 21. When it is determined that the region is the SOF collection region, in step S34, the SOF collection rate βSOF read from the map of FIG. 7 is multiplied by the flow rate distribution rate α to the corresponding filter member 21, An increase in the SOF collection rate is obtained, and an increase amount of the SOF collection amount is obtained by multiplying the SOF accumulation amount W1SOF so far by α × βSOF, and is added to the SOF accumulation amount W1SOF so far. Accordingly, the SOF collection amount WSOF is WSOF = W1SOF × (1 + α × βSOF).

  That is, step S34 and step S35 function as an organic solvent soluble component accumulation amount calculating means. If it is determined that the region is in the SOF separation region, the SOF separation rate γSOF is read from the map of FIG. 7 in step S35, and the flow rate distribution rate α to the corresponding DPF 21 is taken into consideration, and the SOF deposition so far is performed. Multiply the amount W1SOF by α × γSOF to determine the decrease in the amount of SOF collected. Therefore, the final SOF deposition amount WSOF is obtained by multiplying the previous SOF deposition amount W1SOF by (1−α × γSOF).

  Next, in step S36, the particulate deposition amount WPM on the filter member 21, that is, the dry soot deposition amount Wdry and the SOF deposition amount WSOF are added to calculate the PM deposition amount WPM on the DPF.

  Next, control of the DPF regeneration mode in FIG. 8 will be described. The PM accumulation amount has reached the predetermined amount PM1 in the determination of step S5 in the basic flow of FIG. 2, or the SOF accumulation amount has reached the predetermined amount SOF1 in the determination of step S8, and Reg1 flag = 1 is set in step S9. When set, the flow of FIG. 8 is started by the determination in step S4 of the basic flow. In step S101, if necessary, the combustion state is switched so that the DPF temperature becomes a temperature necessary for PM combustion, and the process proceeds to step S102.

  In step S102, the exhaust λ is controlled to be lean for DPF regeneration. Here, the target exhaust λ is set according to the PM deposition amount considered to be deposited on the DPF 21 based on FIG. 9. The target exhaust λ is smaller (rich side) as the PM accumulation amount is larger. This is because as the amount of accumulated PM increases, the PM combustion propagation during the regeneration of the DPF becomes more violent and is easily melted. Control is performed using the intake throttle valve 6, and basically, control is performed so that the target intake air amount shown in FIG. 10 is obtained. If the exhaust λ deviates from the target value, further adjustment is performed. The exhaust λ is controlled to a target value.

  In step S103, it is determined again whether or not the DPF temperature exceeds a predetermined temperature (target lower limit temperature during regeneration, for example, 600 ° C.) T21. This is because the DPF temperature may be lower than T21 by controlling the exhaust λ in step S102. When the DPF temperature is lower than T21, the process proceeds to step S104.

  In step S104, the main fuel injection timing is retarded (retarded) to increase the exhaust temperature, and in step S105, output torque fluctuation due to the retarded injection timing is corrected by increasing the injection amount.

  In step S106, it is determined whether or not the DPF temperature is lower than a target upper limit temperature (for example, 700 ° C.) T22 during regeneration. If the DPF temperature is higher than T22, the process proceeds to step S107.

  In step S107, the main fuel injection timing is advanced to lower the exhaust temperature, and during the regeneration of the DPF, the DPF temperature rises excessively due to PM combustion, thereby preventing the DPF 21 from being melted. Next, in step S108, the output torque fluctuation due to the advance of the injection timing is corrected by adjusting the injection amount to be reduced.

  The exhaust λ varies as the injection amount varies. Thereafter, the target exhaust λ and the DPF temperature are realized by adjusting the intake air amount again in step S102.

  In step S109, it is determined whether or not a predetermined time tdpfreg1 has elapsed in the DPF regeneration mode (target exhaust λ and DPF temperature). If it has elapsed, the PM accumulated in the DPF 21 is reliably burned and removed, so the DPF regeneration is completed. And proceed to step S110.

  In the predetermined time tdpfreg1, as shown in FIG. 11, when the PM deposition amount reaches PM1, the ratio between the DS component and the SOF component constituting the PM differs depending on the operating state. For example, in the case of (A), the low load operation state is continuous, the SOF component reaches the upper limit value SOF1, and the remaining PM is the DS component. In this case, the predetermined time is shown in FIG. As shown by the line A, it is set to a relatively short time. In the case of (C), the high-load operation state is continuous, and there is almost no SOF component and most is occupied by the DS component. The predetermined time in such a case is shown by the line C in FIG. As shown by, set a relatively long time. Further, in the case of (B) between the above (A) and (C), as shown by a line B in FIG.

  Therefore, when it is determined in step S5 that the PM accumulation amount exceeds the predetermined amount PM1 indicating the DPF regeneration timing (PM accumulation amount ≧ PM1), the predetermined time tdpfreg1 starts from case (A) in FIG. It is set according to the ratio of SOF / SOF1 up to case (C). If it is determined in step S8 that the SOF deposition amount exceeds the predetermined amount SOF1 indicating the DPF regeneration timing (SOF deposition amount ≧ predetermined amount SOF1), the ratio of SOF / SOF1 in FIG. Therefore, the predetermined time tdpfreg1 is set to a short time as in the case (A).

  In step S110, since the DPF regeneration is completed, when the combustion is switched in step S101, the combustion state is returned to the original state, and the process proceeds to step S111.

  In step S111, the reg1 flag is set to 0 because DPF regeneration is completed.

  In the above-described embodiment, a description will be given of what makes the regeneration time of the DPF 21 different depending on the ratio of SOF / SOF1 depending on the ratio of SOF / SOF1 when the PM deposition amount exceeds the predetermined amount PM1 and when the SOF deposition amount exceeds the predetermined amount SOF1. However, although not shown, the regeneration temperature of the DPF 21 may be made different between when the PM deposition amount exceeds the predetermined amount PM1 and when the SOF deposition amount exceeds the predetermined amount SOF1.

  In the present embodiment, the following effects can be achieved.

  (A) A particulate collection filter provided in the exhaust passage, and a regeneration means attached to the particulate collection filter and regenerating the collection filter by burning and removing particulates accumulated in a predetermined amount or more on the collection filter. , Fuel property detection means for detecting at least one fuel property among cetane number, octane number, evaporability, calorific value, and aromatic hydrocarbon content of the fuel used, and an operating state for detecting the engine operating state Based on the detection means, the engine operation state detected by the operation state detection means, and the fuel property detected by the fuel property detection means, the amount of particulates collected and deposited on the particulate collection filter is determined. A deposit amount calculating means for calculating together with the component, and a deposit amount and a component calculated by the deposit amount calculating means; And a reproduction operation control means for controlling the reproducing operation of said reproducing means. For this reason, the accumulation amount of the SOF component and the DS component collected in the DPF can be accurately estimated, the regeneration of the DPF can be performed at an appropriate timing, and the lifetime can be extended.

  (A) The accumulation amount calculating means collects and deposits on the particulate collection filter based on the engine operating state detected by the operating state detecting means and the fuel property detected by the fuel property detecting means. And the organic solvent soluble component ratio in the total deposition amount can be calculated, and the regeneration operation control means calculates the organic solvent soluble component amount in the total deposition amount calculated by the deposition amount calculation means. Accordingly, since the regeneration processing time is shortened, the regeneration of the DPF can be appropriately performed according to the deposition component.

  (C) The accumulation amount calculating means collects and deposits on the particulate collection filter based on the engine operating state detected by the operating state detecting means and the fuel property detected by the fuel property detecting means. Since the organic solvent-soluble component amount in the organic solvent-soluble component amount can be calculated, the regeneration operation control unit is activated when the organic solvent-soluble component amount calculated by the deposition amount calculation unit reaches a predetermined amount. It is possible to reliably prevent the function from deteriorating due to the deposition of the organic solvent soluble component.

  (D) The regeneration operation control means sets the DPF at the same regeneration temperature by setting the combustion removal time (regeneration time) of the regeneration means when depositing a predetermined amount or more of the organic solvent soluble component to a relatively short time. It is possible to regenerate, and it is not necessary to change the regeneration temperature for each deposited component, and regeneration control can be simplified.

  (E) The accumulation amount calculation means is such that the temperature of the particulate collection filter from the exhaust gas temperature history or the engine operation history by the operation state detection means has been higher than a predetermined temperature from the previous regeneration operation for a predetermined time. In this case, the amount of organic solvent-soluble component accumulated is calculated as zero, so that the amount of organic solvent-soluble component accumulated in the DPF can be accurately estimated.

  (F) Intake air amount detection means for detecting the intake air amount, Fuel supply amount detection means for detecting the fuel supply amount, and Real air / fuel ratio detection means for detecting the actual air / fuel ratio, Since the specific gravity of the fuel is detected based on the detected intake air amount, fuel supply amount, and actual air-fuel ratio, the specific gravity is detected from the intake air amount, fuel supply amount, and actual air-fuel ratio. In addition, as a fuel supply amount detection means, by obtaining the fuel injection amount as map data from the detected engine speed and load, the function originally provided in the engine can be diverted, There is no increase in cost. Further, the actual fuel supply weight is obtained by dividing the intake air flow rate by the actual air-fuel ratio, and the actual specific gravity is obtained by dividing the actual fuel supply weight by the main fuel injection amount (fuel supply amount). The fuel property can be detected with high accuracy and without an increase in cost, and the fuel property is obtained after taking the standard specific gravity in consideration of the fuel temperature, so that the fuel property can be detected with higher accuracy.

(Second Embodiment)
FIG. 13 is a flowchart of the exhaust gas purification control by the DPF that is periodically executed by the control unit 30 showing the second embodiment of the exhaust gas purification apparatus for the internal combustion engine to which the present invention is applied. In the present embodiment, the regeneration of the DPF is performed when either the DS component or the SOF component constituting the PM reaches the upper limit value. The same devices as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

  The configuration of the engine system to which the exhaust gas purification apparatus for an internal combustion engine according to the present embodiment is applied is the same as that of the first embodiment, and a part of the flowchart of the exhaust gas purification control periodically executed by the engine control unit 30 is As shown in FIG.

  That is, the step S3 for calculating the PM deposition amount collected and deposited in the DPF 21 in the processing procedure (flow chart) of the first embodiment is replaced with the step S21 for detecting the deposition amount of the DS component on the DPF 21. The configuration is different in that step S5 for comparing the amount with the upper limit value PM1 is replaced with step S22 for comparing the DS component accumulation amount with the upper limit value DS1.

  That is, in FIG. 13, the detection of the DS component deposition amount on the DPF 21 in step S21 includes steps S31 and S32 in FIG. 4 for detecting the PM deposition amount. The dry soot deposition amount Wdry of steps S31 and S32 = W1dry + α × Δdry × ηdry is calculated here. In step S22, the dry soot deposition amount Wdry is compared with the upper limit DS1.

  Since the process of step S3 has been changed to step S21, the process of calculating the SOF deposition amount WSOF of the DPF 21 of step S6 reads the WSOF calculated in step S3, so the processes of steps S33 to S35 of FIG. And the SOF deposition amount WSOF = W1SOF × (1 + α × βSOF) or WSOF = W1SOF × (1−α × γSOF) is calculated.

  Further, the upper limit values DS1 and SOF1 of the DS deposition amount and the SOF deposition amount in step S22 and step S8 are set so that the sum of the DS component and the SOF component does not exceed the PM upper limit value PM1. It is desirable to set a lower value.

  The predetermined time tdpfreg1 in step S109 is set depending on whether the regeneration flag reg1 is set in the determination of the upper limit value DS1 of the DS component accumulation amount (step S22) or the upper limit value SOF1 of the SOF component accumulation amount (step S8). . That is, the predetermined time tdpreg1 when the regeneration flag reg1 is set by the determination at the upper limit value SOF1 of the SOF component accumulation amount is larger than that when the regeneration flag reg1 is set by the determination at the upper limit value DS1 of the DS component accumulation amount. A short time is desirable.

  In the present embodiment, in addition to the effects (a) to (f) in the first embodiment, the following effects can be achieved.

(G) The accumulation amount calculating means collects and deposits on the particulate collection filter based on the engine operating state detected by the operating state detecting means and the fuel property detected by the fuel property detecting means. It is possible to calculate the amount of carbonaceous component in the
The regeneration operation control means is activated when the carbonaceous component amount calculated by the accumulation amount calculating means reaches a predetermined amount, and therefore, the DPF can be regenerated at an appropriate time according to the carbonaceous component amount. it can.

1 is a configuration diagram of an engine system to which an exhaust gas purification apparatus for an internal combustion engine of the present invention is applied. The flowchart of the exhaust gas purification control performed by the controller of one Embodiment of the exhaust gas purification apparatus of the internal combustion engine of this invention. The flowchart which shows the detail of the control routine of a fuel property detection. The flowchart which shows the detail of the control routine of PM accumulation amount detection to DPF. The characteristic figure which shows the dry soot discharge | emission amount per unit time at the time of low and medium load. Characteristic chart showing dry soot and SOF emissions for each cetane number at low / medium load (A) and high load (B), and characteristic showing correction factors for dry soot and SOF emissions for each cetane number Figure (C). The characteristic figure which shows the SOF discharge | emission amount per unit time at the time of low and medium load. The flowchart which shows the control routine of DPF regeneration mode. A table showing the target exhaust λ being regenerated with respect to the PM accumulation amount. The map which shows the target intake air amount for DPF melt | disassembly prevention. The figure which shows the ratio of the dry soot and SOF which accumulate on DPF according to a case. The map which shows the reproduction | regeneration time of DPF. The flowchart of the exhaust gas purification control performed by the controller of 2nd Embodiment of the exhaust gas purification apparatus of the internal combustion engine of this invention.

Explanation of symbols

1 Diesel Engine 7 Air Flow Meter 10 Fuel Injection Device 21 DPF
30 Engine control unit 34 Pressure sensor 36 Accelerator opening sensor 37 Air-fuel ratio sensor 1

Claims (9)

A particulate collection filter provided in the exhaust passage;
Regenerating means for regenerating the collection filter by burning and removing the particulates attached to the particulate collection filter and deposited in a predetermined amount or more on the collection filter;
Fuel property detection means for detecting the cetane number of the fuel used;
An operating state detecting means for detecting an engine operating state;
When the engine operating state detected by the operating state detecting means is low / medium load, the engine is discharged from the engine per unit time for the fuel according to the decrease in the cetane number detected by the fuel property detecting means. The particulate collection is performed by increasing the amount of organic solvent-soluble components and increasing the amount of carbonaceous components discharged from the engine per unit time for fuel according to the increase in cetane number detected by the fuel property detecting means. While calculating the amount of particulates collected and deposited in the filter together with the components,
When the engine operating state detected by the operating state detecting means is a high load, only the amount of carbonaceous component discharged from the engine per unit time for the fuel is the cetane number detected by the fuel property detecting means. A deposition amount calculating means for calculating together with the component the amount of particulates collected and deposited on the particulate collection filter by increasing according to the rise ;
An exhaust gas purification apparatus for an internal combustion engine, comprising: a regeneration operation control unit that controls a regeneration operation of the regeneration unit based on a deposition amount and a component calculated by the accumulation amount calculation unit. The accumulation amount calculation means includes an emission amount map of the amount of carbonaceous components discharged from the engine per unit time for an engine operating state set for each cetane number of fuel, and an engine operating state set for each cetane number of fuel. 2. The internal combustion engine according to claim 1, wherein the accumulation amount of the particulates collected and accumulated in the particulate collection filter is calculated with reference to a collection / separation map of the organic solvent soluble component amount. Exhaust purification equipment. The accumulation amount calculation means multiplies a reference emission map of the amount of carbonaceous components discharged from the engine per unit time with respect to the engine operating state at the reference cetane number and a cetane number correction coefficient map for the reference cetane number of the supplied fuel. The amount of carbonaceous components collected and deposited in the particulate collection filter is calculated, and the standard collection / desorption map of the amount of organic solvent soluble components with respect to the engine operating state at the standard cetane number and the cetane with respect to the standard cetane number of the supplied fuel 2. The exhaust emission control device for an internal combustion engine according to claim 1, wherein the organic solvent soluble component amount collected by the particulate collection filter and separated from the particulate collection filter is calculated by multiplying the value correction coefficient map . The regeneration operation control means is configured such that when the total amount of the carbonaceous component amount collected and deposited by the particulate collection filter calculated by the accumulation amount calculation means and the organic solvent soluble component amount reaches a predetermined amount, The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 3, wherein a regeneration operation of the regeneration means is started . The regeneration operation control means starts the regeneration operation of the regeneration means when the amount of carbonaceous components collected and deposited by the particulate collection filter calculated by the accumulation amount calculation means reaches a predetermined amount. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 3, wherein The regeneration operation control means starts the regeneration operation of the regeneration means when the amount of the organic solvent-soluble component collected and deposited by the particulate collection filter calculated by the accumulation amount calculation means reaches a predetermined amount. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 3, wherein the exhaust gas purification device is an internal combustion engine.   The exhaust purification device for an internal combustion engine according to claim 6, wherein the regeneration operation control means sets the combustion removal time of the regeneration means to be shorter than that at the time of regeneration when carbonaceous components are deposited. The accumulation amount calculating means is used when the temperature of the particulate collection filter from the exhaust gas temperature history or the engine operation history is continuously higher than a predetermined temperature from the previous regeneration operation for a predetermined time by the operating state detecting means. 7. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 6, wherein the accumulation amount of the organic solvent soluble component amount is calculated as zero. The exhaust gas purification apparatus for an internal combustion engine includes an intake air amount detection unit that detects an intake air amount, a fuel supply amount detection unit that detects a fuel supply amount, and an actual air / fuel ratio detection unit that detects an actual air / fuel ratio. ,
The specific gravity detecting means detects the specific gravity of the fuel based on the detected intake air amount, fuel supply amount, and actual air-fuel ratio ,
The internal combustion engine according to any one of claims 1 to 8, wherein the fuel property detecting means detects a cetane number of fuel being used based on a detected specific gravity of the specific gravity detecting means. Exhaust purification equipment.

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