JP2004218508A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent sharp increase in DPF temperature and improve regeneration efficiency, when regeneration is interrupted immediately after start of the regeneration of a PM trap filter (DPF) 15 and then the regeneration is restarted. <P>SOLUTION: A PM remaining amount in DPF 15 when the regeneration is interrupted is calculated. In restarting the regeneration, a regeneration processing temperature (an exhaust temperature increased by delay in main injection timing or the like) is changed depending on the PM remaining amount in interrupting the regeneration and an exhaust-temperature-related parameter (vehicle speed) in restarting the regeneration. In this case, since regeneration processing is performed by a plurality of regeneration steps different in regeneration processing temperature selected depending on the exhaust-temperature-related parameter and a regeneration elapsed time, one of the plurality of steps is selected to change the regeneration processing temperature. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine including a filter in an exhaust passage for trapping particulate matter (PM), which is a particulate matter in exhaust gas, and particularly to a technique for regenerating the filter.
[0002]
[Prior art]
Conventionally, as shown in Patent Literature 1, a PM trapping filter is disposed in an exhaust passage, and at a predetermined regeneration timing, a regeneration process for increasing the temperature of the filter is performed to remove PM trapped by the filter. Burning has been done.
[0003]
[Patent Document 1] JP-A-6-58137
[Problems to be solved by the invention]
By the way, during the regeneration of the PM trapping filter, when the operation state changes and jumps into an operation state in which the regeneration cannot be continued, and the regeneration is interrupted, the partial regeneration state is set and the PM remains unburned. For this reason, if the regeneration processing temperature is not set according to the unburned portion at the time of regeneration interruption when regeneration is resumed, unexpected rise in filter temperature may occur or regeneration efficiency may deteriorate due to insufficient increase in filter temperature. There is a problem such as doing.
[0005]
When raising the exhaust gas temperature to increase the filter temperature, the filter temperature changes in accordance with the exhaust gas temperature on the filter inlet side and the PM accumulation amount (remaining PM amount). This is because an unexpected sudden rise in the filter temperature is caused, and conversely, if the exhaust gas temperature is lowered in a state where the PM remaining amount is small, the filter temperature does not rise sufficiently.
[0006]
The present invention has been made in view of the above-described conventional problems, and when the regeneration is restarted after the PM trapping filter is interrupted, the regeneration efficiency can be improved while suppressing a sharp rise in the filter temperature. The purpose is to do.
[0007]
[Means for Solving the Problems]
Therefore, in the present invention, the PM remaining amount of the filter when the regeneration is interrupted is calculated, and the regeneration processing temperature is changed when the regeneration is resumed, based on the PM remaining amount when the regeneration is interrupted.
[0008]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, by setting the reproduction | regeneration processing temperature at the time of reproduction | regeneration restart, it can suppress the sharp rise of a filter temperature, and can aim at the improvement of reproduction | regeneration efficiency.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of a vehicle diesel engine showing one embodiment of the present invention.
[0010]
The combustion chamber 2 of each cylinder of the diesel engine 1 receives air from an air cleaner 3 of an intake system through an intake compressor 5, an intercooler 6, an intake throttle valve 7, and an intake manifold 8 of a variable nozzle supercharger 4. Is inhaled. The fuel supply system includes a fuel injection valve 9 that guides high-pressure fuel stored therein from a common rail (not shown) and injects fuel into the combustion chamber 2 of each cylinder at an arbitrary timing. In the compression stroke, fuel injection (main injection) is performed, and the fuel is burned by compression ignition. Exhaust gas after combustion is discharged through an exhaust manifold 10 of an exhaust system and an exhaust turbine 11 of a variable nozzle supercharger 4. A part of the exhaust gas is extracted from the exhaust manifold 10 through the EGR passage 12 and returned to the intake manifold 8 through the EGR cooler 13 and the EGR valve 14.
[0011]
Here, in order to purify PM in the exhaust gas discharged from the diesel engine 1, a diesel particulate filter (hereinafter, referred to as "DPF") 15 is provided in an exhaust passage downstream of the exhaust turbine 11, whereby the PM is reduced. Collect.
[0012]
When the amount of accumulated PM increases due to the collection of PM in the DPF 15, the exhaust resistance increases and the operability deteriorates. Therefore, it is determined whether or not it is a predetermined regeneration time, and in the case of the regeneration time, regeneration processing means (means for raising the temperature of the DPF 15, more specifically, the temperature of the exhaust gas flowing into the DPF 15), for example, the fuel injection valve 9 Retarding the fuel injection timing (main injection timing), post-injection as an additional fuel injection during the expansion stroke or the exhaust stroke by the fuel injection valve 9, and decreasing the opening degree of the intake throttle valve 7 (reducing intake air quantity → rich air-fuel ratio) EGR rate by the EGR valve 14) and / or reduction of the supercharging pressure by the variable nozzle type supercharger 4 (reduction of intake air amount → enrichment of air-fuel ratio → increase of exhaust temperature). The DPF 15 is regenerated by burning PM using a combination with control.
[0013]
For this reason, a crank angle signal synchronized with engine rotation is generated in an engine control unit (hereinafter referred to as ECU) 20 for controlling the operation of the fuel injection valve 9, the intake throttle valve 7, the variable nozzle supercharger 4, and the EGR valve 14. Thus, a crank angle sensor 21 that can detect the engine speed, an accelerator opening sensor (including an idle switch that is turned on when the accelerator is off) that detects an accelerator opening (the amount of depression of an accelerator pedal) 22, and an intake air amount 23, an engine temperature sensor 24 for detecting engine coolant temperature, a vehicle speed sensor 25 for detecting vehicle speed, and a differential pressure sensor 26 for detecting a pressure difference across the DPF 15 for detecting a pressure loss in the DPF 15. Of exhaust temperature sensors 27 and 28 for detecting exhaust temperatures at the inlet side and outlet side of the DPF 15, respectively. You have entered.
[0014]
Here, the ECU 20 detects the differential pressure across the DPF 15 based on the signal of the differential pressure sensor 26, and estimates the PM accumulation amount based on the detected differential pressure. Then, the regeneration timing is determined based on the estimated PM accumulation amount, and when the regeneration timing is determined, the regeneration process is performed.
[0015]
Next, specific control contents of the ECU 20 will be described with reference to flowcharts of FIGS.
FIG. 2 is a flowchart of the reproduction timing determination and the reproduction start control, which is repeatedly executed at predetermined time intervals.
[0016]
In step S1, the value of the reproduction flag is determined.
In S2, the signal of the differential pressure sensor 26 is read, and the differential pressure (ΔP) across the DPF 15 is detected.
[0017]
In S3, the exhaust flow rate (Ve) is estimated from the engine speed and the load (accelerator opening) by referring to a predetermined map.
In S4, the PM accumulation amount (PMs) of the DPF 15 is estimated by referring to a predetermined map from the pressure difference (ΔP) before and after the DPF and the exhaust gas flow rate (Ve). Here, since the differential pressure across the DPF increases with an increase in the amount of accumulated PM, the PM accumulated amount is estimated to increase as the differential pressure across the DPF increases. However, the differential pressure across the DPF changes according to the exhaust gas flow rate, and the same. Since the PM accumulation amount becomes larger as the exhaust flow rate increases, the estimated value of the PM accumulation amount is corrected based on the exhaust flow rate.
[0018]
In S5, the PM accumulation amount estimated in S4 is compared with a predetermined value for determining the regeneration timing, and it is determined whether or not PM accumulation amount ≧ predetermined value.
If PM accumulation amount <predetermined value, it is determined that it is not the regeneration time, and the routine returns. If PM accumulation amount ≧ predetermined value, it is determined that the regeneration time (regeneration is required), and the process proceeds to S6.
[0019]
In S6, it is determined whether or not the current operating condition satisfies the regeneration execution condition (reproducible operation state). When the idling operation, the deceleration operation, and the extremely low vehicle speed, the regeneration execution condition is not satisfied. In all other cases, the reproduction execution conditions are satisfied, and the process proceeds to S7 to start the reproduction.
[0020]
In S7, the reproduction flag is set to 1, and the process proceeds to S8.
In S8, the vehicle speed (exhaust gas temperature related parameter) is determined. If the vehicle speed is low, the process proceeds to S8, and the first regeneration step (S = 1) is selected as the regeneration step at the start of regeneration. If the vehicle speed is high, the process proceeds to S10, where the second reproduction step (S = 2) is selected as a reproduction step at the start of reproduction.
[0021]
The regeneration step is a first regeneration step (also known as BPT control) in which the regeneration processing temperature (a target value of the exhaust gas temperature on the DPF inlet side) is T1 (for example, 450 ° C.), and the temperature is T2 (for example, 570 ° C.). There are three types of a second regeneration step (alias: complete regeneration control first stage) and a third regeneration step (alias: complete regeneration control second stage) in which the temperature is T3 (for example, 640 ° C.).
[0022]
FIG. 3 is a flowchart of the first reproduction step (BPT control), which is executed at predetermined time intervals.
In S11, it is determined whether or not the reproducing flag = 1 and S = 1, and if YES, the process proceeds to S12 and thereafter.
[0023]
In S12, it is determined whether or not the reproduction is interrupted. If the reproduction is not interrupted, the process proceeds to S13.
In S13, the control of the first regeneration step is performed as a regeneration process for increasing the temperature of the DPF 15 (the exhaust gas temperature flowing into the DPF 15) for the regeneration of the DPF 15. Specifically, the fuel injection valve 9 retards the fuel injection timing (main injection timing), the fuel injection valve 9 performs post-injection as an additional fuel injection during the expansion stroke or the exhaust stroke, and the opening of the intake throttle valve 7. The exhaust gas temperature is raised by using at least one of the pressure reduction and the reduction of the supercharging pressure by the variable nozzle supercharger 4, and further by using a combination of these with the EGR rate control by the EGR valve 14. The temperature inside the DPF 15 is raised to a temperature at which PM can be burned, and the PM trapped in the DPF 15 is burned and removed. In this case, in particular, in the control of the first regeneration step, the DPF inlet side exhaust temperature is determined by changing the amount of PM newly deposited on the DPF 15 and the amount of PM to be burned and removed as called BPT (Balance Point Temperature) control. The DPF inlet side exhaust temperature sensor 27 detects the actual temperature Tin so as to control the temperature to be balanced (BPT) to, for example, 450 ° C., and the fuel injection timing (main injection timing), post injection amount or post injection timing. , The intake throttle valve opening, the supercharging pressure, the EGR rate and the like are controlled. Since the exhaust gas temperature is low in the low vehicle speed range, complete regeneration is difficult. Therefore, the control is performed so as to prevent the PM accumulation amount from further increasing and wait for a high vehicle speed range in which complete regeneration is possible.
[0024]
In S14, the accumulated PM processing amount (ΣPMd) is calculated according to the subroutine (S101 to S105) in FIG.
In S101, the DPF inlet-side exhaust temperature (Tin) and the outlet-side exhaust temperature (Tout) are detected from the signals of the exhaust temperature sensors 27 and 28, and the DPF temperature (Tbed) is estimated from these. Specifically, it is estimated as Tbed = k × (Tin + Tout) / 2 (k is a constant).
[0025]
In S102, the exhaust flow rate (Ve) is estimated from the engine speed and the load (accelerator opening) by referring to a predetermined map.
In S103, the regeneration speed (PM processing amount per unit time) S is estimated by referring to a map from the DPF temperature (Tbed) and the exhaust flow rate (Ve). Note that the regeneration speed increases as the DPF temperature increases and the exhaust gas flow rate decreases (gas cooling decreases).
[0026]
At S104, the PM processing amount (ΔPMd = S × Δt) is calculated by multiplying the reproduction speed (S) by the execution time interval (Δt) of this routine.
In S105, the regeneration processing amount (ΔPMd) is integrated to determine the accumulated PM processing amount (ΣPMd = ΣPMd + ΔPMd), and the process returns.
[0027]
In S15, it is determined whether a predetermined regeneration interruption condition is satisfied. It is assumed that the regeneration stop condition is satisfied during idling operation, deceleration operation, and extremely low vehicle speed.
When the reproduction interruption condition is not satisfied, the process proceeds to S16.
[0028]
In S16, the vehicle speed (exhaust gas temperature related parameter) is determined. If the vehicle speed is low, the process returns as it is, and the first regeneration step (S = 1) is continued. In step S17, the second reproduction step (S = 2) is selected.
[0029]
The processing (S18 to S22) after the reproduction interruption condition is satisfied will be described later.
FIG. 4 is a flowchart of the second regeneration step (first stage of complete regeneration control), which is executed at predetermined time intervals.
[0030]
In S31, it is determined whether or not the reproduction flag is 1 and S = 2, and if YES, the process proceeds to S32 and thereafter.
In S32, it is determined whether or not the reproduction is interrupted. If the reproduction is not interrupted, the process proceeds to S33.
[0031]
In S33, the control of the second regeneration step is performed as a regeneration process for increasing the temperature of the DPF 15 (the exhaust gas temperature flowing into the DPF 15) for the regeneration of the DPF 15. Specifically, the fuel injection valve 9 retards the fuel injection timing (main injection timing), the fuel injection valve 9 performs post-injection as an additional fuel injection during the expansion stroke or the exhaust stroke, and the opening of the intake throttle valve 7. The exhaust gas temperature is raised by using at least one of the pressure reduction and the reduction of the supercharging pressure by the variable nozzle supercharger 4, and further by using a combination of these with the EGR rate control by the EGR valve 14. The temperature inside the DPF 15 is raised to a temperature at which PM can be burned, and the PM trapped in the DPF 15 is burned and removed. In this case, particularly in the control of the second regeneration step, the DPF inlet side exhaust temperature sensor 27 actually controls the DPF inlet side exhaust temperature to, for example, 570 ° C. so as to be referred to as a complete regeneration control first stage. The fuel injection timing (main injection timing), the post injection amount or the post injection timing, the intake throttle valve opening, the supercharging pressure, the EGR rate, and the like are controlled while detecting the temperature Tin. In the first stage of the complete regeneration control, since the remaining amount of PM is still large, the regeneration processing temperature is suppressed (570 ° C.) to avoid a rapid rise in the DPF temperature.
[0032]
In S34, the accumulated PM processing amount (ΣPMd) is calculated according to the subroutine (S101 to S105) in FIG.
In S35, the reproduction time t1 in the second reproduction step (first stage of complete reproduction control) is measured.
[0033]
In S36, it is determined whether or not a predetermined time has elapsed in the second reproduction step (first stage of complete reproduction control), that is, whether or not the reproduction time t1 has become equal to or longer than the predetermined time. In order to shift to the reproduction step, the process proceeds to S37, where the third reproduction step (S = 3) is selected.
[0034]
If the predetermined time has not elapsed, the process proceeds to S38.
In S38, it is determined whether a predetermined regeneration interruption condition is satisfied. It is assumed that the regeneration stop condition is satisfied during idling operation, deceleration operation, and extremely low vehicle speed.
[0035]
When the reproduction interruption condition is not satisfied, the process proceeds to S39.
In S39, the vehicle speed (exhaust temperature-related parameter) is determined. If the vehicle speed is high, the process returns as it is, and the second regeneration step (S = 2) is continued. In order to return, the process proceeds to S40, and the first reproduction step (S = 1) is selected.
[0036]
The processing (S41 to S45) after the reproduction interruption condition is satisfied will be described later.
FIG. 5 is a flowchart of the third regeneration step (second stage of complete regeneration control), which is executed at predetermined time intervals.
[0037]
In S51, it is determined whether or not the reproducing flag = 1 and S = 3, and if YES, the process proceeds to S52 and thereafter.
In S52, it is determined whether or not the reproduction is suspended. If the reproduction is not suspended, the process proceeds to S53.
[0038]
In S53, the control of the third regeneration step is performed as a regeneration process for increasing the temperature of the DPF 15 (the temperature of the exhaust gas flowing into the DPF 15) for the regeneration of the DPF 15. Specifically, the fuel injection valve 9 retards the fuel injection timing (main injection timing), the fuel injection valve 9 performs post-injection as an additional fuel injection during the expansion stroke or the exhaust stroke, and the opening of the intake throttle valve 7. The exhaust gas temperature is raised by using at least one of the pressure reduction and the reduction of the supercharging pressure by the variable nozzle supercharger 4, and further by using a combination of these with the EGR rate control by the EGR valve 14. The temperature inside the DPF 15 is raised to a temperature at which PM can be burned, and the PM trapped in the DPF 15 is burned and removed. In this case, especially in the control of the third regeneration step, the DPF inlet side exhaust temperature sensor 27 controls the DPF inlet side exhaust temperature to, for example, 640 ° C. so as to be referred to as a complete regeneration control second stage. The fuel injection timing (main injection timing), the post injection amount or the post injection timing, the intake throttle valve opening, the supercharging pressure, the EGR rate, and the like are controlled while detecting the temperature Tin. In the second stage of the complete regeneration control, the regeneration is considerably advanced in the first stage, and the PM remaining amount is reduced. Therefore, the regeneration processing temperature is increased (570 ° C. → 640 ° C.) to achieve the complete regeneration. .
[0039]
In S54, the accumulated PM processing amount (ΣPMd) is calculated according to the subroutine (S101 to S105) in FIG.
In S55, the reproduction time t2 in the third reproduction step (second stage of complete reproduction control) is measured.
[0040]
In S56, it is determined whether or not a predetermined time has elapsed in the third reproduction step (the second stage of the complete reproduction control), that is, whether or not the reproduction time t2 has become equal to or longer than the predetermined time. In order to end the process, the process proceeds to S57, where S = 0.
[0041]
If the predetermined time has not elapsed, the process proceeds to S58.
In S58, it is determined whether a predetermined regeneration interruption condition is satisfied. It is assumed that the regeneration stop condition is satisfied during idling operation, deceleration operation, and extremely low vehicle speed.
[0042]
When the reproduction interruption condition is not satisfied, the process proceeds to S29.
In S59, the vehicle speed (exhaust temperature-related parameter) is determined. If the vehicle speed is high, the process returns as it is, and the third regeneration step (S = 3) is continued. In order to return, the process proceeds to S60, where the first reproduction step (S = 1) is selected.
[0043]
The processing (S61 to S65) after the reproduction interruption condition is satisfied will be described later.
FIG. 6 is a flowchart of the reproduction end control, which is executed at predetermined time intervals.
In S71, it is determined whether or not the reproducing flag = 1 and S = 0, and if YES, the process proceeds to S72 and thereafter.
[0044]
In S72, the reproduction is ended. That is, all the parameters changed to increase the exhaust gas temperature are returned to the normal values, and the regeneration is ended.
In S73, the reproducing flag is reset to 0.
[0045]
In S74, the accumulated PM processing amount ΣPMd, the reproduction times t1, t2, etc. are all initialized to zero.
Next, a case where reproduction is interrupted will be described.
[0046]
In the case of interruption during the first regeneration step (BPT control), if the regeneration interruption condition is satisfied in the determination at S15 in FIG. 3, the process proceeds to S18, and all the parameters changed for increasing the exhaust gas temperature are set to the normal values. To stop playback.
[0047]
In the next S19, the PM remaining amount at the time of the reproduction interruption is calculated. That is, during the regeneration, the accumulated PM processing amount (ΣPMd) is calculated from the regeneration speed and the regeneration time obtained from the DPF temperature and the exhaust gas flow rate. The PM remaining amount (PMn = PMs-ｄPMd) is calculated by subtracting the accumulated PM processing amount (ΣPMd) from (PMs).
[0048]
In the next S20, the PM remaining rate α (%) is calculated by the following equation, and the process returns.
α = PMn / PMs × 100
After the interruption of the reproduction, the process proceeds to S21 in the determination in S12 when the routine of FIG.
[0049]
In S21, it is determined whether a predetermined regeneration restart condition is satisfied. It is assumed that the regeneration restart condition is satisfied when the state of the idle operation, the deceleration operation, and the extremely low vehicle speed, which are the regeneration interruption conditions, is released.
[0050]
If the reproduction resuming condition is not satisfied, the process returns to continue the interrupted state, but if the reproduction resuming condition is satisfied, the process proceeds to S22 for resuming the reproduction.
In S22, the reproduction restart processing at the time of the first reproduction step (BPT control) is performed. This is performed according to the subroutine of FIG.
[0051]
That is, the reproduction step at the time of resuming the reproduction is selected from the PM remaining rate (α) at the time of the resumption of the reproduction and the vehicle speed at the time of the resumption of the reproduction so as to appropriately change the reproduction processing temperature at the time of the resumption of the reproduction.
[0052]
Specifically, the PM remaining rate (α) is divided into two, large and small, according to a predetermined threshold, and the vehicle speed is divided into two, low vehicle speed and high vehicle speed, according to a predetermined threshold. Divide and divide.
[0053]
If the PM residual rate is high, it is necessary to restart the regeneration. Therefore, in the case of a low vehicle speed, the first regeneration step (S = 1) is selected in order to perform the BPT control. The second reproduction step (S = 2) is selected to perform the first stage of the reproduction control.
[0054]
If the PM residual ratio is small, it is considered that the regeneration is almost completed, and the regeneration is terminated according to the routine of FIG. 6 by setting S = 0 regardless of the low vehicle speed or the high vehicle speed.
In the case of interruption during the second regeneration step (first stage of complete regeneration control), if the regeneration interruption condition is satisfied in the determination at S38 in FIG. 4, the process proceeds to S41, and the parameter changed for increasing the exhaust gas temperature. Are returned to the normal values, and the reproduction is interrupted.
[0055]
In the next S42, the PM remaining amount at the time of the reproduction interruption is calculated. That is, during the regeneration, the accumulated PM processing amount (ΣPMd) is calculated from the regeneration speed and the regeneration time obtained from the DPF temperature and the exhaust gas flow rate. The PM remaining amount (PMn = PMs-ｄPMd) is calculated by subtracting the accumulated PM processing amount (ΣPMd) from (PMs).
[0056]
In the next S43, the PM remaining rate α (%) is calculated by the following equation, and the process returns.
α = PMn / PMs × 100
After the interruption of the reproduction, the process proceeds to S44 in the determination in S32 when the routine of FIG.
[0057]
In S44, it is determined whether a predetermined regeneration restart condition is satisfied. It is assumed that the regeneration restart condition is satisfied when the state of the idle operation, the deceleration operation, and the extremely low vehicle speed, which are the regeneration interruption conditions, is released.
[0058]
If the reproduction resuming condition is not satisfied, the process returns to continue the interrupted state, but if the reproduction resuming condition is satisfied, the process proceeds to S45 for resuming the reproduction.
In S45, a reproduction restart process at the time of the second reproduction step (first stage of complete reproduction control) is performed. This is performed according to the subroutine of FIG.
[0059]
That is, the reproduction step at the time of resuming the reproduction is selected from the PM remaining rate (α) at the time of the resumption of the reproduction and the vehicle speed at the time of the resumption of the reproduction so as to appropriately change the reproduction processing temperature at the time of the resumption of the reproduction.
[0060]
Specifically, the PM remaining rate (α) is divided into three, large, medium, and small, according to a predetermined threshold, and the vehicle speed is divided into two, a low vehicle speed and a high vehicle speed, according to the predetermined threshold. Divided into cases.
[0061]
If the PM residual rate is high, it is necessary to restart the regeneration. Therefore, in the case of a low vehicle speed, the first regeneration step (S = 1) is selected in order to perform the BPT control. The second reproduction step (S = 2) is selected to perform the first stage of the reproduction control.
[0062]
When the PM remaining rate is in the middle, the vehicle speed is divided into a low vehicle speed and a high vehicle speed. In the case of a low vehicle speed, since complete reproduction cannot be expected, it is considered that the reproduction is almost completed, and S = 0 is set, and the reproduction is ended by the routine of FIG. In the case of a high vehicle speed, complete reproduction can be expected, so the third reproduction step (S = 3) is selected in order to perform the complete reproduction control second stage.
[0063]
If the PM residual ratio is small, it is considered that the regeneration is almost completed, and the regeneration is terminated according to the routine of FIG. 6 by setting S = 0 regardless of the low vehicle speed or the high vehicle speed.
In the case of interruption during the third regeneration step (second stage of complete regeneration control), if the regeneration interruption condition is satisfied in the determination at S58 in FIG. 5, the process proceeds to S61, where the parameters changed for increasing the exhaust gas temperature are set. Are returned to the normal values, and the reproduction is interrupted.
[0064]
In the next S62, the PM remaining amount at the time of the reproduction interruption is calculated. That is, during the regeneration, the accumulated PM processing amount (ΣPMd) is calculated from the regeneration speed and the regeneration time obtained from the DPF temperature and the exhaust gas flow rate. The PM remaining amount (PMn = PMs-ｄPMd) is calculated by subtracting the accumulated PM processing amount (ΣPMd) from (PMs).
[0065]
In the next S63, the PM remaining rate α (%) is calculated by the following equation, and the process returns.
α = PMn / PMs × 100
After the reproduction is interrupted, the process proceeds to S64 in the determination at S52 when the routine of FIG.
[0066]
In S64, it is determined whether a predetermined reproduction restart condition is satisfied. It is assumed that the regeneration restart condition is satisfied when the state of the idle operation, the deceleration operation, and the extremely low vehicle speed, which are the regeneration interruption conditions, is released.
[0067]
If the reproduction resuming condition is not satisfied, the process returns to continue the interruption state, but if the reproduction resuming condition is satisfied, the process proceeds to S65 for resuming the reproduction.
In S65, the reproduction restart processing at the time of the third reproduction step (the second stage of the complete reproduction control) is performed. This is performed according to the subroutine of FIG.
[0068]
That is, the reproduction step at the time of resuming the reproduction is selected from the PM remaining rate (α) at the time of the resumption of the reproduction and the vehicle speed at the time of the resumption of the reproduction so as to appropriately change the reproduction processing temperature at the time of the resumption of the reproduction.
[0069]
Specifically, the PM remaining rate (α) is divided into two, large and small, according to a predetermined threshold, and the vehicle speed is divided into two, low vehicle speed and high vehicle speed, according to a predetermined threshold. Divide and divide.
[0070]
If the PM residual rate is high, it is necessary to restart the regeneration. Therefore, in the case of a low vehicle speed, the first regeneration step (S = 1) is selected in order to perform the BPT control. The third reproduction step (S = 3) is selected to perform the second stage of the reproduction control.
[0071]
If the PM residual ratio is small, it is considered that the regeneration is almost completed, and the regeneration is terminated according to the routine of FIG. 6 by setting S = 0 regardless of the low vehicle speed or the high vehicle speed.
According to the present embodiment, the PM remaining amount of the DPF 15 when the regeneration is interrupted is calculated, and when the regeneration is resumed, the regeneration is performed according to the PM remaining amount when the regeneration is interrupted and the exhaust temperature-related parameter (for example, the vehicle speed) when the regeneration is resumed. By changing the processing temperature, specifically, by selecting one of a plurality of regeneration steps having different regeneration processing temperatures, the DPF temperature is set appropriately by setting the regeneration processing temperature at the time of resuming the regeneration. Can be suppressed and the regeneration efficiency can be improved.
[0072]
As shown in FIG. 11, the DPF temperature during regeneration changes in accordance with the exhaust gas temperature on the inlet side of the DPF and the amount of accumulated PM (remaining PM amount). If the exhaust gas temperature is lowered while the PM remaining amount is low, the DPF temperature will not rise sufficiently. However, by setting the regeneration processing temperature (exhaust temperature) according to the PM remaining amount, a favorable Reproduction becomes possible.
[0073]
Further, according to the present embodiment, when calculating the PM remaining amount when the regeneration is interrupted, the accumulated PM processing amount is calculated from the regeneration speed and the regeneration time obtained from the DPF temperature and the exhaust flow rate, and By subtracting the accumulated PM processing amount from the PM accumulation amount and calculating the remaining PM amount, the remaining PM amount can be accurately obtained.
[Brief description of the drawings]
FIG. 1 is a system diagram of a diesel engine showing an embodiment of the present invention. FIG. 2 is a flowchart of regeneration timing determination and regeneration start control. FIG. 3 is a flowchart of a first regeneration step. FIG. 4 is a flowchart of a second regeneration step. FIG. 5 is a flowchart of a third regeneration step. FIG. 6 is a flowchart of regeneration end control. FIG. 7 is a flowchart of a cumulative PM processing amount calculation subroutine. FIG. 8 is a flowchart of regeneration restart processing in the first regeneration step. FIG. 10 is a flowchart of a regeneration restart process in a second regeneration step. FIG. 10 is a flowchart of a regeneration restart process in a third regeneration step. FIG. 11 is a diagram showing a relationship between a PM accumulation amount, a regeneration DPF temperature, and the like. ]
DESCRIPTION OF SYMBOLS 1 Diesel engine 4 Variable nozzle supercharger 7 Intake throttle valve 9 Fuel injection valve 14 EGR valve 15 DPF
20 ECU
21 Crank angle sensor 22 Accelerator opening sensor 26 Differential pressure sensor 27 DPF inlet side exhaust temperature sensor 28 DPF outlet side exhaust temperature sensor

Claims (4)

A regeneration timing determining means for determining a regeneration timing of the filter while providing a filter for trapping PM in the exhaust gas in the exhaust passage; and a regeneration process for increasing the temperature of the filter when the regeneration timing of the filter is determined. The exhaust gas purification device of the internal combustion engine, comprising:
Means for suspending regeneration when a predetermined regeneration interruption condition is satisfied during regeneration of the filter, and resuming regeneration when a predetermined regeneration restart condition is satisfied after the regeneration is interrupted;
A regeneration interruption PM remaining amount calculating means for calculating the PM remaining amount of the filter at the time of the interruption of the regeneration,
At the time of the resumption of the regeneration, a regeneration process temperature variable unit at the time of the regeneration resumption that changes the regeneration process temperature based on the remaining PM at the time of the regeneration interruption,
An exhaust gas purification device for an internal combustion engine, comprising: 2. The regeneration processing temperature varying means at the time of regeneration resumption changes the regeneration processing temperature in accordance with the remaining PM amount at the time of regeneration interruption and an exhaust temperature-related parameter at the time of regeneration resumption. Exhaust purification device for internal combustion engine. The regeneration processing by the regeneration processing means includes a plurality of regeneration steps in which the regeneration processing temperature selected by the exhaust temperature-related parameter and the elapsed regeneration time is different,
The reproduction-restart-time reproduction-processing-temperature varying means is a reproduction-restart-time reproduction-step selection means for selecting one of the plurality of reproduction steps in order to change the reproduction processing temperature. An exhaust purification device for an internal combustion engine according to claim 2. The regeneration interruption time remaining PM calculating means calculates an accumulated PM processing amount from the regeneration speed and the regeneration time obtained from the temperature of the filter and the exhaust flow rate, and calculates the accumulated PM processing amount from the PM accumulation amount at the start of the regeneration. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the PM amount is calculated by subtracting the amount.

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