JP2009041514A - Catalyst bed temperature control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of a catalyst regeneration type filter due to overheating, by preventing a control error of a catalyst bed temperature when regenerating the filter. <P>SOLUTION: During a setting period of an initial target catalyst bed temperature, a quantity of integral control QI corresponding to a difference between a quantity of post injection Qpst and an actual quantity of post injection is learned, based on an offset target catalyst bed temperature Tofst that is lower than a normal target catalyst bed temperature (S142). A highly accurate quantity of integral control QI is calculated because the target catalyst bed temperature is stable at the offset target catalyst bed temperature Tofst during setting the initial target catalyst bed temperature. Accordingly, thereafter, by setting a target catalyst bed temperature at the time of normal regeneration as the target catalyst bed temperature, even in a transient period, since the quantity of post injection Qpst is controlled by using the highly accurate quantity of integral control QI previously learned, highly the catalyst bed temperature is precisely controlled. When the catalyst bed temperature reaches the target catalyst bed temperature, because heating of the quantity of integral control QI including a large error with overshoot is not applied, the damage of the DPF due to overheating is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus for controlling a catalyst bed temperature during regeneration in a catalyst regeneration type filter that is provided in an exhaust system of an internal combustion engine and collects particulates from exhaust gas.

  There is known a system in which a filter is disposed in an exhaust passage of a diesel engine to collect particulate matter (PM) in exhaust gas, and the collected PM is burned and removed by heat-treating the filter (for example, Patent References 1 to 5).

In Patent Document 1, a smooth oxidation reaction is caused by performing fuel addition step by step during filter regeneration processing, thereby preventing clogging of the filter and white smoke.
In Patent Literature 2, the control amount such as the post injection amount is gradually changed to a set value by switching the target temperature during the filter regeneration process, thereby preventing an excessive increase in the filter temperature and a sudden change in the operation state.

In Patent Document 3, a rapid increase in the temperature of the filter is prevented by gradually changing the target temperature in accordance with the PM accumulation amount.
In Patent Document 4, in order to perform complete filter regeneration, the target temperature is divided into two stages and the heat regeneration process is performed.

In Patent Document 5, melting of the filter is prevented by increasing the target bed temperature stepwise.
JP 2004-132316 A (Page 6, FIG. 4) Japanese Patent Laying-Open No. 2005-90390 (5th page, FIG. 2-4) Japanese Patent Laying-Open No. 2005-120981 (page 4-6, FIG. 2-9) Japanese Patent Laying-Open No. 2004-183525 (page 7-9, FIG. 5) Japanese Patent Laying-Open No. 2002-250218 (page 5-8, FIG. 2)

  In Patent Documents 2 to 5 described above, variations in the fuel injection valve and the fuel addition valve that determine the post-injection amount and the fuel addition amount, which are heating adjustment amounts, are not considered. For this reason, an excessive amount of fuel may be injected or added with respect to the valve control amount due to variations in the fuel injection valve and the fuel addition valve.

  In particular, at the initial stage of the regeneration of the filter, the filter tends to be higher than the target bed temperature due to overshoot in feedback control. If a fuel injection valve or fuel addition valve that injects or adds an excessive amount of fuel with respect to the valve control amount is used in the early stage of regeneration, the overheated state will exceed the limit of the filter and will dissolve in the filter. Damage and other damage will occur.

  Due to variations in the fuel injection valve and the fuel addition valve, the fuel injection amount or the addition amount may be too small relative to the valve control amount. In such a case, in Patent Documents 2 to 5, since the valve control amount is proportional to the difference between the target temperature and the actual temperature by the proportional control as the feedback control, the fuel injection amount and the addition amount are insufficient at the initial stage of the regeneration control. Playback takes time.

  In order to solve such a control error problem, in Patent Document 1, feedback control using a proportional control amount and an integral control amount is executed after the catalyst bed temperature has sufficiently approached the target temperature.

  However, the initial stage of feedback control is a transient state up to the target temperature, and it is difficult to obtain the integral control amount with high accuracy, and there is a possibility that an error has accumulated in the integral control amount when the filter reaches the target temperature. There is. For this reason, a completely opposite situation occurs in which a control error is caused by the integral control amount. Also in this case, if the integral control amount is excessive, the filter may be overheated due to an excessive fuel injection amount or fuel addition amount.

  It is an object of the present invention to suppress a catalyst bed temperature control error during regeneration of a catalyst regeneration type filter and prevent damage to the filter due to overheating.

In the following, means for achieving the above object and its effects are described.
The catalyst bed temperature control apparatus according to claim 1 is an apparatus that controls a catalyst bed temperature during regeneration in a catalyst regeneration type filter that is provided in an exhaust system of an internal combustion engine and collects particulates from exhaust gas, At the start of regeneration of the catalyst regeneration type filter, an initial target catalyst bed temperature setting period is set in which an initial target catalyst bed temperature lower than the regeneration target catalyst bed temperature is set as the target catalyst bed temperature, and after the initial target catalyst bed temperature setting period Target catalyst bed temperature setting means for setting the target catalyst bed temperature during regeneration as the target catalyst bed temperature, and heating adjustment amount correction corresponding to the difference between the heating adjustment amount and the actual heating amount within the initial target catalyst bed temperature setting period Initial target catalyst bed temperature setting period learning means for learning a value, catalyst bed temperature detection means for detecting the actual catalyst bed temperature of the catalyst regeneration filter, and target catalyst bed temperature set by the target catalyst bed temperature setting means And the catalyst bed temperature detection hand And the heating adjustment amount is controlled based on the difference from the actual catalyst bed temperature detected in step S1, and after the heating adjustment amount correction value is learned by the initial target catalyst bed temperature setting period learning means, Heating adjustment amount control means for controlling the heating adjustment amount using the heating adjustment amount correction value together with the difference between the bed temperature and the actual catalyst bed temperature is provided.

  Within the initial target catalyst bed temperature setting period, the initial target catalyst bed temperature setting period learning means learns a heating adjustment amount correction value corresponding to the difference between the heating adjustment amount and the actual heating amount. In this way, the learning of the heating adjustment amount correction value that reflects the control error of the fuel injection valve, the fuel addition valve, etc. is performed in a state where the initial target catalyst bed temperature lower than the target catalyst bed temperature during regeneration is set as the target catalyst bed temperature. It is running.

  For this reason, even if the regeneration control is started, control for converging the catalyst bed temperature at a lower initial target catalyst bed temperature is performed before the temperature is raised to the regeneration target catalyst bed temperature. For this reason, even if there is a possibility that an error may accumulate in the heating adjustment amount correction value at the initial stage of the initial target catalyst bed temperature setting period, the target catalyst bed temperature is within the initial target catalyst bed temperature setting period. Thus, the error in the heating adjustment amount correction value during this period can be sufficiently reduced by learning.

  Therefore, after the initial target catalyst bed temperature setting period, the target catalyst bed temperature setting means sets the regeneration target catalyst bed temperature as the target catalyst bed temperature. It is required with high accuracy in a sufficiently lowered state.

  For this reason, the heating adjustment amount control means thereafter calculates a heating adjustment amount correction value in which variations in the fuel injection valve, the fuel addition valve, etc. are learned with high accuracy along with the difference between the target catalyst bed temperature during regeneration and the actual catalyst bed temperature. Since the heating adjustment amount can be controlled by using this, it is possible to perform highly accurate catalyst bed temperature control in which a control error is suppressed.

  Therefore, even when the regeneration target catalyst bed temperature is reached, the heating adjustment amount correction value including a large error is not applied to the overshoot, so that the filter can be prevented from being damaged due to overheating.

  The catalyst bed temperature control apparatus according to claim 2, wherein the heating adjustment amount is controlled based on a difference between the target catalyst bed temperature and the actual catalyst bed temperature in the initial stage of the initial target catalyst bed temperature setting period. Proportional control means is provided, and the initial target catalyst bed temperature setting period learning means learns the heating adjustment amount correction value after completion of control by the proportional control means.

  In the initial stage of the initial target catalyst bed temperature setting period, the proportional control means controls the heating adjustment amount based on the difference between the target catalyst bed temperature and the actual catalyst bed temperature. Therefore, the catalyst bed temperature is in a sufficiently stable state by proportional control before the initial target catalyst bed temperature setting period learning means actually learns the heating adjustment amount correction value. Therefore, the initial target catalyst bed temperature setting period learning means starts learning from a state in which both the target catalyst bed temperature and the actual catalyst bed temperature are stable, so that the heating adjustment amount correction value can be learned with almost no error.

This enables more accurate catalyst bed temperature control.
The catalyst bed temperature control apparatus according to claim 3, wherein the heating adjustment amount is an adjustment amount of fuel added to the exhaust gas, and the actual heating amount is actually added to the exhaust gas. It is characterized by the amount of fuel.

  In this case, it is possible to calculate the heating adjustment amount correction value in which the variation in the fuel injection valve and the fuel addition valve is learned with high accuracy, and by using this to control the heating adjustment amount, the control error can be reduced. Suppressed and highly accurate catalyst bed temperature control becomes possible.

  The catalyst bed temperature control device according to claim 4 is characterized in that in claim 3, the amount of fuel added to the exhaust gas is adjusted by adjusting the post injection amount performed in the combustion chamber of the internal combustion engine. And

Thus, the regeneration control of the filter may be executed by adjusting the post injection amount performed in the combustion chamber.
According to a fifth aspect of the present invention, there is provided the catalyst bed temperature control device according to the third aspect, wherein the amount of fuel added to the exhaust gas is adjusted by adjusting the fuel addition amount performed by the fuel addition valve provided in the exhaust passage. It is characterized by that.

Thus, the regeneration control of the filter may be executed by adjusting the fuel addition amount performed by the fuel addition valve provided in the exhaust path.
The catalyst bed temperature control apparatus according to claim 6, wherein the target catalyst bed temperature setting means sets the target catalyst bed temperature to an initial target after the initial target catalyst bed temperature setting period. The catalyst bed temperature is gradually shifted from the catalyst bed temperature to the target catalyst bed temperature during regeneration.

  As described above, even after the initial target catalyst bed temperature setting period, the target catalyst bed temperature is gradually shifted from the initial target catalyst bed temperature to the regeneration target catalyst bed temperature, so that the temperature of the filter does not rise rapidly. Since the temperature distribution in the filter is not greatly biased, the filter can be prevented from being damaged.

  The catalyst bed temperature control device according to claim 7, wherein the heating adjustment amount control means learns the heating adjustment amount correction value after the initial target catalyst bed temperature setting period. The heating adjustment amount is controlled in a state in which the heating is continued.

  Thus, the heating adjustment amount control means may continue learning the heating adjustment amount correction value even after the initial target catalyst bed temperature setting period. In this case as well, the basis of continuing learning is the heating adjustment amount correction value learned during the initial target catalyst bed temperature setting period. For this reason, in the subsequent catalyst bed temperature control, it is possible to perform highly accurate control in which the control error is suppressed. Therefore, even when the regeneration target catalyst bed temperature is reached, the heating adjustment amount correction value including a large error is not applied to the overshoot, and damage to the filter due to overheating can be prevented.

  The catalyst bed temperature control apparatus according to claim 8, wherein the heating adjustment amount control means is the initial target catalyst bed temperature setting period after the initial target catalyst bed temperature setting period. The heating adjustment amount is controlled in a state where the heating adjustment amount correction value learned by the learning means is fixed.

  As described above, the heating adjustment amount control means may be used as a value obtained by fixing the heating adjustment amount correction value after the initial target catalyst bed temperature setting period. Since the heating adjustment amount correction value has already been learned with high accuracy within the initial target catalyst bed temperature setting period, even in the subsequent catalyst bed temperature control, high-accuracy control with suppressed control error becomes possible. . Therefore, even when the regeneration target catalyst bed temperature is reached, the heating adjustment amount correction value including a large error is not applied to the overshoot, and damage to the filter due to overheating can be prevented.

  The catalyst bed temperature control device according to claim 9, wherein the heating adjustment amount correction value obtained by learning is an integral control amount in catalyst bed temperature feedback control in any one of claims 1 to 8. And

  Thus, by obtaining the integral control amount in the catalyst bed temperature feedback control as the heating adjustment amount correction value, it is possible to learn variations in the fuel injection valve, the fuel addition valve, and the like. By using this integral control amount, it is possible to perform highly accurate catalyst bed temperature control in which control errors are suppressed.

  The catalyst bed temperature control device according to claim 10, wherein in any one of claims 1 to 9, an upper limit setting means for limiting the heating adjustment amount by setting an upper limit value of the heating adjustment amount, and the upper limit setting And an upper limit changing means for correcting the upper limit value set by the means in accordance with the magnitude of the heating adjustment amount correction value.

  If the upper limit value of the heating adjustment amount is set from the limit of the heating adjustment range, the control deviation of the heating adjustment amount is reflected in the heating adjustment amount correction value. By correcting according to the size, an appropriate upper limit value can be set.

  The catalyst bed temperature control apparatus according to claim 11, wherein the upper limit changing unit performs addition correction for adding the heating adjustment amount correction value to the upper limit value set by the upper limit setting unit. It is characterized by performing.

The upper limit value can be changed to an appropriate upper limit value by addition correction of the heating adjustment amount correction value.
The catalyst bed temperature control apparatus according to claim 12, wherein the target catalyst bed temperature setting means controls the initial target catalyst bed temperature setting period by the heating adjustment amount control means in any one of claims 1 to 11. It is set by the elapsed time from the start.

Thus, by setting the initial target catalyst bed temperature setting period based on the elapsed time, it is possible to give a margin for learning a highly accurate heating adjustment amount correction value in the catalyst bed temperature control.
The catalyst bed temperature control apparatus according to claim 13, wherein the target catalyst bed temperature setting means controls the initial target catalyst bed temperature setting period by the heating adjustment amount control means in any one of claims 1 to 11. From the start to the time when the variation of the heating adjustment amount correction value learned by the initial target catalyst bed temperature setting period learning means becomes smaller than the reference variation range.

  In this way, by setting the initial target catalyst bed temperature setting period until the fluctuation of the heating adjustment amount correction value becomes smaller than the reference fluctuation range, in the catalyst bed temperature control within the initial target catalyst bed temperature setting period. A highly accurate heating adjustment amount correction value can be learned.

  The catalyst bed temperature control apparatus according to claim 14, further comprising: a stable operation state detection unit that detects a stable operation state of the internal combustion engine according to any one of claims 1 to 13, wherein the initial target catalyst bed temperature setting period learning unit is provided. Is performed only when the internal combustion engine is determined to be in a stable operation state by the stable operation state detection means, and learning of the heating adjustment amount correction value is executed.

  Thus, only when it is determined that the internal combustion engine is in a stable operation state, the initial target catalyst bed temperature setting period learning means may function. If the internal combustion engine is in a stable operating state, a highly accurate heating adjustment amount correction value can be obtained early.

  The catalyst bed temperature control device according to claim 15, further comprising a regeneration request operation detection means for detecting a regeneration request operation from a driver of the internal combustion engine in a stable operation state of the internal combustion engine according to any one of claims 1 to 13. The initial target catalyst bed temperature setting period learning means performs learning of the heating adjustment amount correction value only when a regeneration request operation is detected by the regeneration request operation detection means.

  As described above, the initial target catalyst bed temperature setting period learning means may function when there is a regeneration request operation from the driver during the stable operation state of the internal combustion engine. The driver can be aware of the regeneration of the filter, and at the same time, it is possible to keep the internal combustion engine conscious and maintained at the same time. Can get to.

The catalyst bed temperature control device according to a sixteenth aspect is the one according to the fifteenth aspect, wherein the stable operation state of the internal combustion engine is an idle operation state.
Since the stability of the internal combustion engine operation is high when idling, a highly accurate heating adjustment amount correction value can be obtained reliably at an early stage.

[Embodiment 1]
FIG. 1 shows a schematic configuration of a diesel engine (hereinafter abbreviated as an engine) 2 as an internal combustion engine to which the present invention is applied, and a control system thereof. The engine 2 is an internal combustion engine for driving a vehicle, and drives the vehicle to travel by its output. In each cylinder 4 of the engine 2, an intake valve 6, an exhaust valve 8, and a fuel injection valve 10 for directly injecting fuel into the combustion chamber are arranged.

  The fuel injection valve 10 communicates with a common rail 12 that accumulates fuel to a predetermined pressure, and the common rail 12 communicates with a fuel pump 16 that is rotationally driven by the engine 2 via a fuel supply pipe 14. The pressurized fuel distributed from the common rail 12 to the fuel injection valve 10 of each cylinder 4 is opened by applying a predetermined drive current to the fuel injection valve 10, and as a result, the fuel injection valve Fuel is injected from 10 into the cylinder 4.

  An intake manifold 18 is connected to the engine 2, and each branch pipe of the intake manifold 18 communicates with the combustion chamber of each cylinder 4 via an intake port. The intake manifold 18 is connected to an intake pipe 20, and the intake pipe 20 is connected to an air cleaner 22 on the upstream side. In the middle of the intake pipe 20, a compressor 24a of the turbocharger 24 is disposed. The compressor 24a compresses intake air by rotation on the turbine 24b side.

  An intercooler 26 is disposed in the intake pipe 20 downstream of the compressor 24a for cooling the intake air that has been compressed by the compressor 24a and has reached a high temperature. An intake throttle valve 28 for restricting the intake amount is attached to the intake pipe 20 downstream of the intercooler 26, and the opening degree of the intake throttle valve 28 is adjusted by an electric actuator 30.

  An exhaust manifold 32 is connected to the engine 2, and each branch pipe of the exhaust manifold 32 communicates with the combustion chamber of each cylinder 4 through an exhaust port. The exhaust manifold 32 is connected to the exhaust pipe 34 via the turbine 24 b of the turbocharger 24. In the turbine 24b, an internal turbine wheel is rotated by receiving the pressure of exhaust gas, and a rotational driving force is transmitted to the compressor 24a side.

  An exhaust purification device 36 is disposed in the middle of the exhaust pipe 34. In the exhaust gas purification device 36, an oxidation catalyst (DOC) 36a is disposed on the upstream side, and a particulate filter (DPF) 36b is disposed on the downstream side. A catalyst bed temperature sensor 38 (corresponding to catalyst bed temperature detection means) is disposed between the DOC 36a and the DPF 36b, and detects the temperature of the exhaust gas flowing into the DPF 36b from the DOC 36a. An exhaust gas temperature sensor 40 is also arranged upstream of the exhaust gas purification device 36 to detect the temperature of the exhaust gas flowing into the exhaust gas purification device 36. Further, an exhaust differential pressure sensor 41 for introducing the exhaust pressure between the upstream side and the downstream side of the exhaust purification device 36 is provided to detect the exhaust pressure difference ΔPex between the upstream side and the downstream side.

An exhaust pipe 34 downstream of the exhaust purification device 36 is provided with an exhaust throttle valve 42 that adjusts the exhaust flow rate. The opening / closing operation of the exhaust throttle valve 42 is performed by an actuator 44.
The intake manifold 18 introduces a part of the exhaust gas flowing through the exhaust manifold 32 through an exhaust gas recirculation passage (EGR passage) 46. An EGR valve 48 that adjusts the flow rate of the EGR gas flowing in the EGR passage 46 is provided in the middle of the EGR passage 46. An EGR cooler 50 that cools the EGR gas is provided at a portion upstream of the EGR valve 48.

  An electronic control unit (ECU) 52 for controlling the engine operating state for such an engine 2 is provided. The ECU 52 is a control circuit that controls the engine operating state in accordance with the engine operating state and the driver's request, and is configured around a microcomputer including a CPU, a ROM, a RAM, a backup RAM, and the like.

  The above-described catalyst bed temperature sensor 38, exhaust temperature sensor 40, and exhaust differential pressure sensor 41 are connected to the ECU 52. Further, a crank position sensor 54 for detecting the crankshaft rotation of the engine 2, a coolant temperature sensor 56 for detecting the engine coolant temperature, and an accelerator opening sensor 58 for detecting the operation amount (accelerator opening) of the accelerator pedal are connected. . Further, a fuel pressure sensor 60 for detecting the fuel pressure of the common rail 12, an intake air amount sensor 62 for detecting the intake air amount GA, and other sensors and switches are connected. As a result, output signals of various sensors and switches are input to the ECU 52.

  The ECU 52 is electrically connected to the fuel injection valve 10, the EGR valve 48, the actuator 30 for the intake throttle valve 28, and the actuator 44 for the exhaust throttle valve 42. Control is being executed.

  Next, the DPF catalyst bed temperature control process executed by the ECU 52 will be described. This DPF catalyst bed temperature control process is a process executed when PM accumulates in the DPF 36b over a reference amount or when the exhaust pressure difference ΔPex becomes larger than the reference differential pressure.

  FIG. 2 shows a flowchart of the DPF catalyst bed temperature control process. This process is interrupted at a time period. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When this process is started, it is first determined whether or not it is a PM regeneration request (S102). For example, when the PM accumulation amount reaches the reference accumulation amount for regeneration due to the engine operation history, or when the exhaust pressure difference ΔPex detected by the exhaust differential pressure sensor 41 exceeds the reference differential pressure, the PM regeneration request is made. It is time.

  If it is not at the time of PM regeneration request (No in S102), the regeneration initial determination counter Cint is cleared (S104), and this processing is exited. Therefore, when it is not at the time of PM regeneration request, only the regeneration initial determination counter Cint is cleared (S104) every control cycle, and no substantial processing is performed.

  If a PM regeneration request has been made (yes in S102), it is next determined whether or not the initial temperature rise has been completed (S106). Initially, since the initial temperature increase has not yet been performed (no in S106), the initial temperature increase is executed (S108). The initial temperature increase is a process for preliminarily increasing the temperature of the DPF 36b before the catalyst bed temperature feedback control. Specifically, the post injection amount Qpst (mm3 / st: injected fuel volume per engine rotation) obtained by the post injection amount map MAPpst used when controlling to the target catalyst bed temperature at which PM regeneration is actually performed is The fuel is injected from the fuel injection valve 10 at the post injection timing. The post-injection amount map MAPpst is as shown in FIG. 5, and the main fuel injection amount Qf calculated by the separately executed main fuel injection amount control and the engine speed NE detected by the crank position sensor 54. Is a map for obtaining the post injection amount Qpst.

  This initial temperature increase is continued for a predetermined initial temperature increase period (for example, 80 seconds). While the initial temperature increase period has not elapsed (no in S106), the execution of the initial temperature increase with the post injection amount Qpst described above (S108) continues.

  Since the initial temperature increase is completed when the initial temperature increase period elapses (yes in S106), the regeneration initial determination counter Cint is incremented by increment (S110). Then, it is determined whether feedback control based on the offset target catalyst bed temperature is completed (S112). This determination is made based on whether or not the elapsed time of the catalyst bed temperature feedback control performed after the completion of the initial temperature increase has elapsed, for example, 150 seconds. At first, since the feedback control based on the offset target catalyst bed temperature is not performed, it is determined as no, and the feedback control based on the offset target catalyst bed temperature is executed (S114). The details of the feedback control process based on the offset target catalyst bed temperature are shown in the flowchart of FIG.

In the control of FIG. 3, first, the offset target catalyst bed temperature Tofst is calculated by Equation 1 (S132).
[Formula 1] Tofst ←
MAPbase (Mpm) + MAPga (GA) + MAPofs (Cint)
Here, the base target catalyst bed temperature map MAPbase is as shown in FIG. 6, and is a map for obtaining the base target catalyst bed temperature (° C.) from the PM accumulation amount Mpm (g) in the DPF 36b. The intake air amount GA offset map MAPga is as shown in FIG. 7, and the larger the intake air amount GA detected by the intake air amount sensor 62, the larger the exhaust flow rate correspondingly. For this reason, when the intake air amount GA is increased, the degree of offset is increased to prevent thermal runaway of PM combustion in the DPF 36b.

  As shown in FIG. 8, the PM regeneration initial target catalyst bed temperature offset map MAPofs is a map for offsetting the target catalyst bed temperature in the early stage of PM regeneration based on the elapsed time represented by the regeneration initial determination counter Cint. Here, an offset of −100 ° C. is performed from the start of counting of the reproduction initial determination counter Cint to the value of the reproduction initial determination counter Cint corresponding to 150 seconds. Therefore, the offset target catalyst bed temperature Tofst is set 100 ° C. lower than the level obtained from the base target catalyst bed temperature map MAPbase and the intake air amount GA offset map MAPga. From 150 seconds to 250 seconds, the target catalyst bed temperature offset gradually decreases, and the offset disappears at 250 seconds. That is, the offset target catalyst bed temperature Tofst actually reaches the normal target catalyst bed temperature level.

  When the offset target catalyst bed temperature Tofst is calculated in step S132, the temperature difference dT from the actual catalyst bed temperature Tcat detected by the catalyst bed temperature sensor 38 is calculated as shown in equation 2 below. (S134).

[Formula 2] dT ← Tofst-Tcat
Based on this temperature difference dT, the proportional control amount QP in the post injection amount is calculated from the proportional control amount map MAPp shown in FIG. 9 (S136).

  Next, in step S110 (FIG. 2), it is determined whether or not the value of the reproduction initial determination counter Cint that has started timing has become equal to or greater than the PI control start reference value Cpi (S138). Here, the PI control start reference value Cpi is set to be shorter than the determination time (here, 150 seconds) until the feedback control is completed by the offset target catalyst bed temperature in step S112. Here, a value corresponding to 50 seconds is set.

  Accordingly, if 50 seconds have not elapsed after the initial temperature rise is completed (FIG. 2: yes in S106), Cint <Cpi (no in S138), and therefore, the proportional control variable that does not use the integral control variable according to Equation 3 The feedback control by QP is executed and the post injection amount Qpst is calculated (S140).

[Formula 3] Qpst <-Qofsbase + Qh + QP
Here, the offset basic post injection amount Qofsbase is calculated from the offset post injection amount map MAPofspst. The offset post-injection amount map MAPofspst is as shown in FIG. 10, and the offset basic post-injection amount Qofsbase is obtained from the main fuel injection amount Qf calculated separately and the engine speed NE detected by the crank position sensor 54. It is a map. The post-injection amount map MAPpst shown in FIG. 5 is different from the post-injection amount used in step S108 because the target catalyst bed temperature is offset by −100 ° C. as the offset target catalyst bed temperature. The injection amount is low. The transient correction amount Qh is a correction amount that is set based on changes in the engine speed NE and the intake air amount GA in order to prevent overheating in a transient state such as the exhaust flow rate.

  Thus, in step S114, feedback control (S140) is performed with a proportional control amount that does not use the integral control amount with respect to the offset target catalyst bed temperature, and the DPF catalyst bed temperature control process (FIG. 2) is temporarily exited.

  Even in the next control cycle, yes in step S102, yes in step S106, and when the count-up of the reproduction initial determination counter Cint is executed (S110), if Cint <Cpi (<150 seconds) thereafter, Again, no is determined in step S112. Even after entering the feedback control process (FIG. 3) based on the offset target catalyst bed temperature, it is determined no in step S138. Therefore, during the period of Cint <Cpi, feedback control of the post injection amount Qpst by the proportional control amount is performed without using the integral control amount shown in Equation 3 (S140).

  Thereafter, while Cint <Cpi, the feedback control of the post injection amount Qpst by the proportional control amount is continued without using the integral control amount so that the actual catalyst bed temperature Tcat converges to the offset target catalyst bed temperature Tofst. .

  When the regeneration initial determination counter Cint reaches the PI control start reference value Cpi, that is, when the feedback control state of the post injection amount Qpst by the proportional control amount not using the integral control amount has elapsed for 50 seconds, it is determined as yes in step S138. It becomes like this. As a result, the integral control amount QI is then calculated from Equation 4 based on the temperature difference dT (S142).

[Formula 4] QI <-QI + MAPi (dT)
Here, the integral control amount QI on the right side represents the integral control amount set in the previous control cycle, and the initial value is set to 0 (mm 3 / st) when the ECU 52 is started. If the PM regeneration request is not requested in the DPF catalyst bed temperature control process (FIG. 2) (no in S102), the integral control amount QI may be cleared together with the regeneration initial determination counter Cint in step S104.

The integral value MAPi (dT) is a value (mm3 / st) calculated based on the temperature difference dT obtained in step S134 from the integral value map MAPi shown in FIG.
When the integral control amount QI is calculated in this way, the feedback control based on the proportional control amount and the integral control amount is executed by the equation 5 together with the proportional control amount QP calculated in step S136, and the post injection amount Qpst is calculated. Calculated (S144).

[Formula 5] Qpst <-Qofsbase + Qh + QP + QI
Here, the offset basic post-injection amount Qofsbase, the transient correction amount Qh, and the proportional control amount QP are as described in Equation 3 above.

  Thus, in step S114, feedback control (S144) based on the proportional control amount and the integral control amount with respect to the offset target catalyst bed temperature is executed, and the DPF catalyst bed temperature control process (FIG. 2) is temporarily exited.

  Thereafter, proportional control is performed so that the actual catalyst bed temperature Tcat converges to the offset target catalyst bed temperature Tofst while the count value of the regeneration initial determination counter Cint does not reach the time until feedback control by the offset target catalyst bed temperature is completed. The feedback control of the post injection amount Qpst by the amount and the integral control amount is continued.

  When it is determined by the regeneration initial determination counter Cint that the feedback control based on the offset target catalyst bed temperature has been completed, here, when 150 seconds have elapsed from the completion of the initial temperature increase, it is determined as yes in step S112. Therefore, feedback control based on the target catalyst bed temperature, that is, feedback control of the catalyst bed temperature is performed while changing from the offset target catalyst bed temperature Tofst to the normal target catalyst bed temperature Tt that is not offset (S116).

The details of the feedback control process (S116) based on the target catalyst bed temperature are shown in the flowchart of FIG.
In the control of FIG. 4, first, the target catalyst bed temperature Tt is calculated by Equation 6 (S152).

[Formula 6] Tt ←
MAPbase (Mpm) + MAPga (GA) + MAPofs (Cint)
The right side of Equation 6 is the same as Equation 1. However, as shown in FIG. 8, the absolute value of the target catalyst bed temperature offset MAPofs (Cint) decreases with time, and finally when the regeneration initial determination counter Cint reaches the offset end time limit Cend (here, 250 seconds). The target catalyst bed temperature offset MAPofs (Cint) converges to 0 (° C.). Therefore, in PM regeneration control that is in a continuous state after Cint = Cend, the target catalyst bed temperature is no longer offset by the target catalyst bed temperature offset MAPofs (Cint).

  When the target catalyst bed temperature Tt is calculated in step S152 as described above, a temperature difference dT from the actual catalyst bed temperature Tcat detected by the catalyst bed temperature sensor 38 is calculated as shown in Equation 7 below. (S154).

[Formula 7] dT ← Tt − Tcat
Based on the temperature difference dT, the proportional control amount QP is calculated from the above-described proportional control amount map MAPp shown in FIG. 9 (S156). Further, based on the temperature difference dT, the integral control amount QI is calculated by the equation 4 (S158).

  Next, it is determined whether or not the reproduction initial determination counter Cint is greater than or equal to the offset end deadline value Cend (S160). Here, a value corresponding to 250 seconds is set as the offset end deadline value Cend.

  At first, since Cint <Cend (no in S160), the basic post injection amount Qb used for calculating the post injection amount Qpst is gradually shifted from the offset basic post injection amount Qofsbase to the normal basic post injection amount Qbase. A setting process is executed (S162). The offset basic post injection amount Qofsbase is a value calculated from the offset post injection amount map MAPofspst in FIG. 10, and the normal basic post injection amount Qbase is a value calculated from the post injection amount map MAPpst in FIG. .

For example, the basic post injection amount Qb is calculated by Equation 8.
[Formula 8] Qb <-{(nm) · Qofsbase + m · Qbase} / n
Here, the variable n is set to a fixed count value corresponding to 100 seconds, and the variable m corresponds to the elapsed time from the reproduction initial determination counter Cint = a value corresponding to 150 seconds to an offset end deadline value Cend (here, a value corresponding to 250 seconds). The count value to be set is set.

  Initially, m = 0 second equivalent value and n = 100 second equivalent value. Therefore, from the above equation 8, the basic post injection amount Qb is set to the offset basic post injection amount Qofsbase as it is.

Then, using this basic post injection amount Qb, the post injection amount Qpst is calculated by Equation 9 (S166).
[Formula 9] Qpst <-Qb + Qh + QP + QI
Here, the transient correction amount Qh, the proportional control amount QP, and the integral control amount QI are as described in the expressions 3 and 5.

Thus, the DPF catalyst bed temperature control process (FIG. 2) is temporarily exited.
After the next control cycle, the value of the basic post injection amount Qb gradually shifts from the offset basic post injection amount Qofsbase to the normal basic post injection amount Qbase in step S162. With the shift of the basic post injection amount Qb, the post injection amount Qpst (S166: Equation 9) obtained by feedback control also shifts from the offset state to the amount corresponding to the normal PM regeneration state.

  When the regeneration initial determination counter Cint reaches the offset end deadline value Cend, Cint ≧ Cend (yes in S160), so that the normal basic post injection amount Qbase (FIG. 5) is set as it is as the basic post injection amount Qb. (S164). Then, the post-injection amount Qpst is calculated by Equation 9 (S166).

  Thereafter, until the PM regeneration control is completed, it is determined as yes in step S160, and therefore the processing (S164, S166) for calculating the post injection amount Qpst by the basic post injection amount Qbase is continued.

  When the PM regeneration process is completed, since it is determined as no in step S102 of the DPF catalyst bed temperature control process (FIG. 2), the regeneration initial determination counter Cint is cleared (S104), and the process is left as it is. Therefore, the substantial process in the DPF catalyst bed temperature control process (FIG. 2) ends.

  An example of control in the present embodiment is shown in the timing chart of FIG. In the example of FIG. 12, the fuel injection valve 10 is used whose fuel injection amount is shifted to the larger side with respect to the standard fuel injection valve. When the PM regeneration request time is reached (t0), the initial temperature rise (FIG. 2: S108) is executed (t0 to t1). Thereafter, feedback control is performed with a proportional control amount that does not use the integral control amount at the offset target catalyst bed temperature (t1 to t2, FIG. 3: S132, S140). Subsequently, feedback control using the proportional control amount and the integral control amount is performed at the offset target catalyst bed temperature (t2 to t3, FIG. 3: S132 and S144). Thus, since feedback control is executed at the offset target catalyst bed temperature, the overshoot of the actual catalyst bed temperature Tcat is suppressed and does not exceed the limit temperature (OT). Then, the integral control amount QI is obtained with high accuracy while being stably controlled to the offset target catalyst bed temperature. Then, the offset target catalyst bed temperature is gradually increased from the normal target catalyst bed temperature (t3 to t4, FIG. 4: S152, S162, S166), and then the control is completely shifted to the normal target catalyst bed temperature. (T4 to t5, FIG. 4: S152, S164, S166). This enables highly accurate catalyst bed temperature control at a normal target catalyst bed temperature.

  In the timing chart of FIG. 13 shown as a comparative example, initial temperature rise (t10 to t11), feedback control (t11 to t12) using a proportional control amount that does not use an integral control amount, and feedback control between a proportional control amount and an integral control amount ( t12 to t17) are executed. However, in the feedback control (t11 to t17), a normal target catalyst bed temperature that is not offset from the beginning is used. Therefore, as in this comparative example, if the fuel injection amount of the fuel injection valve 10 varies larger than the control amount, the limit temperature (OT) is exceeded (t13 to t14, t15 to t16).

  In the configuration described above, the relationship with the claims is as follows: Steps S102 to S112 of the DPF catalyst bed temperature control process (FIG. 2); Step S132 of the feedback control process (FIG. 3) using the offset target catalyst bed temperature; Step S152 of the control process (FIG. 4) corresponds to the process as the target catalyst bed temperature setting means. Step S112 of the DPF catalyst bed temperature control process (FIG. 2) and step S142 of the feedback control process using the offset target catalyst bed temperature (FIG. 3) correspond to the process as the initial target catalyst bed temperature setting period learning means. The feedback control process based on the offset target catalyst bed temperature (FIG. 3) and the feedback control process based on the target catalyst bed temperature (FIG. 4) correspond to the process as the heating adjustment amount control means. Steps S136 and S140 of the feedback control process (FIG. 3) based on the offset target catalyst bed temperature correspond to the process as the proportional control means.

According to the first embodiment described above, the following effects can be obtained.
(I). Based on the temperature difference dT between the offset target catalyst bed temperature Tofst and the actual catalyst bed temperature Tcat during the initial target catalyst bed temperature setting period (t2 to t3), the post injection amount Qpst (corresponding to the heating adjustment amount) and the actual post injection amount ( The integral control amount QI (corresponding to the heating adjustment amount correction value) corresponding to the difference from the actual heating amount) is learned (S142). Thus, the learning of the integral control amount QI that reflects the control error due to the variation of the fuel injection valve 10 is performed by the offset target catalyst bed temperature Tofst (the target catalyst bed temperature offset MAPofs (Cint)) lower than the normal target catalyst bed temperature. The initial target catalyst bed temperature is set to the target catalyst bed temperature.

  Therefore, before the DPF 36b is raised to the normal target catalyst bed temperature, control is performed to converge the catalyst bed temperature of the DPF 36b once at a lower offset target catalyst bed temperature Tofst. For this reason, in the initial stage of the initial target catalyst bed temperature setting period, there is a possibility that an error is accumulated in the integral control amount QI. However, within the initial target catalyst bed temperature setting period, the target catalyst bed temperature is the offset target catalyst bed temperature. Since it is stable as Tofst, the error in the integral control amount QI can be sufficiently reduced during this period.

  Therefore, by setting the target catalyst bed temperature Tt at the time of normal regeneration as the target catalyst bed temperature after the initial target catalyst bed temperature setting period, the error in the integral control amount QI has already been obtained even during the transition (t3 to t4). Is required with high accuracy in a sufficiently lowered state.

  Therefore, the post-injection amount Qpst is subsequently controlled using the integral control amount QI in which the variation in the fuel injection valve 10 is learned with high accuracy as described above together with the difference dT between the target catalyst bed temperature Tt and the actual catalyst bed temperature Tcat. As a result, it is possible to perform highly accurate catalyst bed temperature control in which control errors are suppressed.

  For this reason, even when the target catalyst bed temperature Tt is reached, the integral control amount QI including a large error is not heated with respect to the overshoot, so that the DPF 36b can be prevented from being damaged due to overheating.

  (B). In the initial stage of the initial target catalyst bed temperature setting period, the post injection amount Qpst is controlled by catalyst bed temperature feedback control using a proportional control amount that does not use the integral control amount (FIG. 3: S136, S140). Therefore, the catalyst bed temperature of the DPF 36b is sufficiently stabilized by proportional control before actually learning the integral control amount QI. Therefore, since the integral control amount QI starts learning from a state where both the offset target catalyst bed temperature Tofst and the actual catalyst bed temperature Tcat are stable (S142), the integral control amount QI can be learned with almost no error. This makes it possible to control the catalyst bed temperature with higher accuracy.

  (C). After the initial target catalyst bed temperature setting period (t1 to t3), the target catalyst bed temperature Tt is gradually shifted from the offset state to the normal target catalyst bed temperature (S162). As a result, since the temperature of the DPF 36b is not rapidly increased, the temperature distribution in the DPF 36b is not largely biased. For this reason, damage to the DPF 36b can be prevented.

  (D). Even after the transition to the normal target catalyst bed temperature (t3), learning of the integral control amount QI is continued by taking over the integral control amount QI during the offset period. For this reason, in the subsequent catalyst bed temperature control (t3 to t5), high-accuracy control in which control errors are suppressed is possible. Even when the target catalyst bed temperature Tt is reached, heating for the integral control amount QI including a large error is not applied to the overshoot, and damage to the DPF 36b due to overheating can be prevented.

[Embodiment 2]
In the present embodiment, feedback control based on the target catalyst bed temperature shown in FIG. 14 is executed instead of feedback control processing (FIG. 4) based on the target catalyst bed temperature. Other configurations are the same as those of the first embodiment.

  In the feedback control process (FIG. 14) based on the target catalyst bed temperature, step S252 is the same process as steps S152 to S164 in FIG. Therefore, after the basic post-injection amount Qb is obtained in step S162 or step S164, the post-injection amount upper limit value Qpstlmt is calculated by equation 10 (S254).

[Formula 10] Qpstlmt
← MIN (Qpstlmtb, Qpstlmmtgn, Qpstmx) + QI
Here, the catalyst bed temperature upper limit Qpstlmtb is a post-injection amount upper limit set based on the actual catalyst bed temperature Tcat. The air-fuel ratio upper limit value Qpstlmtgn is a post-injection amount upper limit value that is set based on the air-fuel ratio A / F that is the ratio of the intake air amount GA to the total injection amount of the main injection amount and the post-injection amount. The high temperature prevention upper limit value Qpstmx is a post injection amount upper limit value set to prevent the exhaust purification device 36 from overheating. MIN () is an operator that extracts the minimum value among the three numerical values (Qpstlmtb, Qpstlmmtgn, Qpstmx) in parentheses. Further, in the above equation 10, addition correction for the integral control amount QI is executed on the minimum value extracted by MIN ().

  In this way, the post injection amount upper limit value Qpstlmt is corrected by the integral control amount QI reflecting the variation of the fuel injection valve 10, so that the post injection amount upper limit value Qpstlmt that offsets the variation of the fuel injection valve 10 is obtained. .

  In the above-described configuration, steps S102 to S112 of the DPF catalyst bed temperature control process (FIG. 2), feedback control process (FIG. 3) based on the offset target catalyst bed temperature (step S132), and feedback control process (FIG. 14) based on the target catalyst bed temperature. The process corresponding to step S152 corresponds to the process as the target catalyst bed temperature setting means. Step S112 of the DPF catalyst bed temperature control process (FIG. 2) and step S142 of the feedback control process using the offset target catalyst bed temperature (FIG. 3) correspond to the process as the initial target catalyst bed temperature setting period learning means. The feedback control process based on the offset target catalyst bed temperature (FIG. 3) and the feedback control process based on the target catalyst bed temperature (FIG. 14) correspond to the process as the heating adjustment amount control means. Steps S136 and S140 of the feedback control process (FIG. 3) based on the offset target catalyst bed temperature correspond to the process as the proportional control means. In step S254 of the feedback control process based on the target catalyst bed temperature (FIG. 14), the term “MIN (Qpstlmtb, Qpstlmmtgn, Qpstmx)” is the process as the upper limit setting unit, and the term “+ QI” is the process as the upper limit changing unit. Equivalent to.

According to the second embodiment described above, the following effects can be obtained.
(I). The effect of the first embodiment is produced.
(B). When the upper limit value of the post-injection amount Qpst (post-injection amount upper limit value Qpstlmt) is set as in Expression 10, the integral control amount QI is added and corrected, so that variations in the fuel injection valve 10 are offset. An appropriate post injection amount upper limit value Qpstlmt can be set.

  Therefore, when the fuel injection valve 10 varies on the excessive injection side, the DPF 36b can be prevented from overheating, and when the fuel injection valve 10 varies on the excessive injection side, insufficient regeneration of the DPF 36b can be prevented.

[Embodiment 3]
In the present embodiment, the DPF catalyst bed temperature control process of FIG. 15 is executed instead of the DPF catalyst bed temperature control process (FIG. 2), and FIG. 16 shows the feedback control process (FIG. 4) based on the target catalyst bed temperature. The feedback control based on the target catalyst bed temperature shown is executed. Further, the vehicle dashboard is provided with a PM regeneration switch (corresponding to a regeneration request operation detecting means) that can be instructed by a driver during idling. If the ECU 52 finds that the driver is instructing a PM regeneration request by turning on the PM regeneration switch during idling, the ECU 52 performs PM regeneration as manual regeneration. Other configurations are the same as those of the first embodiment.

  Steps S304 to S308 and S314 to S318 in the DPF catalyst bed temperature control process (FIG. 15) are the same as steps S104 to S108 and S110 to S114 in FIG. In the determination of whether or not the PM regeneration request is executed at the beginning of this control (S302), the PM regeneration request from the driver by the PM regeneration switch is also determined.

  In the DPF catalyst bed temperature control process (FIG. 15), after completion of the initial temperature increase (yes in S306), it is determined whether or not manual regeneration is being performed (S310). That is, it is determined whether the PM regeneration request from the driver is made by the PM regeneration switch, and if it is determined that manual regeneration is in progress (yes in S310), the regeneration initial determination counter Cint is incremented (S314). Hereinafter, the processing as described in the first embodiment is performed. In other words, if it is determined that the engine is being manually regenerated at the time of idling (yes in S310), the processing is performed substantially as described in the first embodiment, and the feedback control is performed based on the offset target catalyst bed temperature Tofst. It is possible to calculate the integral control amount QI at.

  When it is not at the time of manual regeneration, that is, at the time of automatic regeneration based on the PM accumulation amount or the exhaust gas pressure difference ΔPex upstream and downstream of the exhaust purification device 36 (No in S310), the regeneration initial determination counter Cint includes the offset target catalyst bed temperature. In order to avoid feedback control in Tofst, “250” is set (S312). If it is 250 or more, a larger value may be set in the reproduction initial determination counter Cint. Immediately thereafter, feedback control based on the normal target catalyst bed temperature Tt is executed (S320). The flowchart of FIG. 16 represents feedback control based on the target catalyst bed temperature Tt.

  Steps S352 to S356 and S360 to S368 in FIG. 16 are the same as S152 to S166 in FIG. A difference from FIG. 4 is whether manual regeneration is performed or not (S358) after calculation of the proportional control amount QP (S356) and before calculation of the integral control amount QI (S360). If manual regeneration is in progress (yes in S358), the process proceeds to integral control amount QI calculation (S360). Therefore, at the time of manual regeneration, the same processing as in the first embodiment is performed.

  If it is not during manual regeneration (no in S358), that is, during automatic regeneration, the basic post injection amount Qbase when the target catalyst bed temperature is not offset is immediately set in the basic post injection amount Qb. Processing is executed (S366). Then, the post-injection amount Qpst is calculated by the equation 9 (S368). Note that, although the integral control amount QI is included in the above equation 9, if it is not during manual regeneration, learning of the integral control amount QI (S142, S360) is not actually executed, so the integral control amount QI = 0. In the case where the ECU 52 holds the value of the integral control amount QI learned during a period other than the manual regeneration in the past, the value of the integral control amount QI may be used even during the manual regeneration. In this case, the integral control amount QI is not learned and is kept constant.

  Here, steps S302 to S308, S314, and S316 of the DPF catalyst bed temperature control process (FIG. 15), step S132 of the feedback control process using the offset target catalyst bed temperature (FIG. 3), and the feedback control process using the target catalyst bed temperature (FIG. 16). ) Step S352 corresponds to the processing as the target catalyst bed temperature setting means. Step S142 of the feedback control process (FIG. 3) based on the offset target catalyst bed temperature and steps S310 and S316 of the DPF catalyst bed temperature control process (FIG. 15) correspond to the process as the initial target catalyst bed temperature setting period learning means. The feedback control process based on the offset target catalyst bed temperature (FIG. 3) and the feedback control process based on the target catalyst bed temperature (FIG. 16) correspond to the process as the heating adjustment amount control means. Steps S136 and S140 of the feedback control process (FIG. 3) based on the offset target catalyst bed temperature correspond to the process as the proportional control means.

According to the third embodiment described above, the following effects can be obtained.
(I). When there is a PM regeneration request operation from the driver during idling, which is when the engine 2 is in a stable operation state, feedback control based on the offset target catalyst bed temperature is executed. This produces the effect of the first embodiment.

  Furthermore, since the driver can execute the operation while paying attention to the regeneration of the DPF 36b, the driver can simultaneously maintain the engine 2 in a stable state. In particular, since the engine is idling, a highly accurate integral control amount QI can be reliably obtained at an early stage.

[Embodiment 4]
In the present embodiment, the DPF catalyst bed temperature control process of FIG. 17 is executed instead of the DPF catalyst bed temperature control process (FIG. 2), and FIG. 18 is substituted for the feedback control process (FIG. 3) based on the offset target catalyst bed temperature. The feedback control based on the offset target catalyst bed temperature shown in FIG. Further, instead of the target catalyst bed temperature offset map MAPofs (FIG. 8) at the initial stage of PM regeneration, the gradually decreasing offset map MAPofs shown in FIG. 19 is used. Other configurations are the same as those of the first embodiment.

  Steps S402 to S408 and S416 of the DPF catalyst bed temperature control process (FIG. 17) are the same processes as steps S102 to S108 and S116 in FIG. In the DPF catalyst bed temperature control process (FIG. 17), when the initial temperature rise is completed (yes in S406), it is determined whether or not the integral control amount QI in the feedback control (S414) based on the offset target catalyst bed temperature is stabilized. (S410). Immediately after the completion of the initial temperature increase, feedback control (S414) based on the offset target catalyst bed temperature has not yet been executed, and the integral control amount QI itself has not been accumulated (No in S410). Feedback control based on the bed temperature (S414) is executed.

  Details of the feedback control (S414) based on the offset target catalyst bed temperature are as shown in FIG. 18, steps S434, S436, and S440 to S444 are the same processes as steps S134, S136, and S140 to S144 in FIG. In step S432, a fixed value of “−100 (° C.)” is used in place of MAPofs (Cint) in Equation 1. In step S438, it is determined whether 50 seconds have elapsed since the start of feedback control. Based on this determination, the switching timing from the feedback control calculation (S440) based on the proportional control amount QP not using the integral control amount QI to the feedback control calculation (S444) based on the proportional control amount QP and the integral control amount QI is determined.

  When the value of the integral control amount QI obtained in step S442 in FIG. 18 is stabilized, for example, when the fluctuation width per unit time of the integral control quantity QI falls within the reference fluctuation width indicating stabilization (yes in S410), First, counting up of the reproduction initial determination counter Cint is started (S412). Then, according to the setting of the offset map MAPofs in FIG. 19 corresponding to the regeneration initial determination counter Cint, the feedback control process (FIG. 4) based on the target catalyst bed temperature described in the first embodiment is executed. As a result, the value of the basic post injection amount Qb gradually shifts from the offset basic post injection amount Qofsbase to the basic post injection amount Qbase (S162). Then, when the regeneration initial determination counter Cint reaches the offset end deadline value Cend, here 100 seconds (yes in S160), the normal basic post injection amount Qbase is set as it is as the basic post injection amount Qb. (S164). The other processes in FIG. 4 are as described in the first embodiment.

  Here, steps S402 to S410 of the DPF catalyst bed temperature control process (FIG. 17), step S432 of the feedback control process (FIG. 18) based on the offset target catalyst bed temperature, and the feedback control process (FIG. 4) based on the target catalyst bed temperature. S152 corresponds to the processing as the target catalyst bed temperature setting means. Step S410 of the DPF catalyst bed temperature control process (FIG. 17) and step S442 of the feedback control process using the offset target catalyst bed temperature (FIG. 18) correspond to the process as the initial target catalyst bed temperature setting period learning means. The feedback control process (FIG. 18) based on the offset target catalyst bed temperature and the feedback control process (FIG. 4) based on the target catalyst bed temperature correspond to the process as the heating adjustment amount control means. Steps S436 and S440 of the feedback control process (FIG. 18) based on the offset target catalyst bed temperature correspond to the process as the proportional control means.

According to the fourth embodiment described above, the following effects can be obtained.
(I). In the present embodiment, the initial target catalyst bed temperature setting period is set to the time when the fluctuation of the integral control amount QI becomes smaller than the reference fluctuation width. This also provides a highly accurate integral control amount QI and produces the effect of the first embodiment.

[Other embodiments]
(A). In the third embodiment, in step S302 of FIG. 15, when the PM accumulation amount has reached the reference accumulation amount based on the engine operation history, or the exhaust pressure difference ΔPex detected by the exhaust differential pressure sensor 41 becomes the reference differential pressure. In addition to the above case, the presence of a PM regeneration request from the driver was also included. Instead of the presence of the PM regeneration request from the driver, as a stable operation state detection unit, a unit for detecting the stable operation state of the engine 2, for example, a certain amount of PM accumulation when the vehicle is running at a constant speed If a certain degree of upstream / downstream differential pressure has occurred, the determination may be made as yes in step S302. And in step S310 and step S358 of FIG. 16, you may make it determine with yes when it exists in the stable operation state by a stable operation state detection means.

  As a result, it is possible to increase the learning chance of the highly accurate integral control amount QI and execute appropriate PM regeneration control. In this PM regeneration control, it is possible to prevent damage to the DPF 36b due to overheating.

  (B). In each of the above-described embodiments, learning of the integral control amount QI is executed even after the feedback control based on the offset target catalyst bed temperature Tofst is completed. Instead of this, the integral control amount QI learned at the time of feedback control by the offset target catalyst bed temperature Tofst is not learned by the feedback control by the target catalyst bed temperature Tt immediately after that, and the learned integral control amount QI is fixed. Alternatively, feedback control by adjusting only the proportional control amount QP may be executed.

  (C). In each of the above embodiments, the PM regeneration is performed by heating the DPF 36b by the post injection of the fuel injection valve 10 that injects the fuel into the combustion chamber. Instead, a fuel addition valve is arranged in the exhaust manifold 32 or the exhaust pipe 34, and fuel is added to the exhaust gas from the fuel addition valve to supply the added fuel as a heating adjustment amount to the exhaust purification device 36. Also good.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic structure explanatory drawing of the diesel engine of Embodiment 1, and its control system. 4 is a flowchart of DPF catalyst bed temperature control processing executed by the ECU according to the first embodiment. The flowchart of the feedback control processing by offset target catalyst bed temperature similarly. Similarly, the flowchart of the feedback control process by target catalyst bed temperature. FIG. 3 is a configuration explanatory diagram of a post injection amount map MAPpst used in the control of the first embodiment. FIG. 3 is a configuration explanatory diagram of a base target catalyst bed temperature map MAPbase used in the control according to the first embodiment. FIG. 3 is a configuration explanatory diagram of an intake air amount GA offset map MAPga used in the control according to the first embodiment. FIG. 3 is a configuration explanatory diagram of a target catalyst bed temperature offset map MAPofs at the initial stage of PM regeneration used in the control of the first embodiment. FIG. 3 is a configuration explanatory diagram of a proportional control amount map MAPp used in the control of the first embodiment. FIG. 3 is a configuration explanatory diagram of an offset post injection amount map MAPofspst used in the control according to the first embodiment. FIG. 3 is a configuration explanatory diagram of an integral value map MAPi used in the control according to the first embodiment. 4 is a timing chart illustrating an example of control according to the first embodiment. 4 is a timing chart illustrating an example of control as a comparative example with respect to the first embodiment. 10 is a flowchart of feedback control processing based on a target catalyst bed temperature according to the second embodiment. 10 is a flowchart of DPF catalyst bed temperature control processing according to the third embodiment. 10 is a flowchart of feedback control processing based on a target catalyst bed temperature according to the third embodiment. 10 is a flowchart of DPF catalyst bed temperature control processing according to the fourth embodiment. 10 is a flowchart of feedback control processing based on an offset target catalyst bed temperature according to the fourth embodiment. FIG. 10 is a configuration explanatory diagram of an offset map MAPofs according to the fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Engine, 4 ... Cylinder, 6 ... Intake valve, 8 ... Exhaust valve, 10 ... Fuel injection valve, 12 ... Common rail, 14 ... Fuel supply pipe, 16 ... Fuel pump, 18 ... Intake manifold, 20 ... Intake pipe, 22 DESCRIPTION OF SYMBOLS ... Air cleaner, 24 ... Turbocharger, 24a ... Compressor, 24b ... Turbine, 26 ... Intercooler, 28 ... Intake throttle valve, 30 ... Electric actuator, 32 ... Exhaust manifold, 34 ... Exhaust pipe, 36 ... Exhaust gas purification device, 36a ... Oxidation catalyst (DOC), 36b ... Particulate filter (DPF), 38 ... Catalyst bed temperature sensor, 40 ... Exhaust temperature sensor, 41 ... Exhaust differential pressure sensor, 42 ... Exhaust throttle valve, 44 ... Actuator, 46 ... EGR passage 48 ... EGR valve, 50 ... EGR cooler, 52 ... ECU, 54 ... Crank position sensor, 56 ...却水 temperature sensor, 58 ... accelerator opening sensor, 60: fuel pressure sensor, 62 ... intake air quantity sensor.

Claims (16)

An apparatus for controlling a catalyst bed temperature during regeneration in a catalyst regeneration filter that is provided in an exhaust system of an internal combustion engine and collects particulates from exhaust,
At the start of regeneration of the catalyst regeneration type filter, an initial target catalyst bed temperature setting period is set in which an initial target catalyst bed temperature lower than the regeneration target catalyst bed temperature is set as the target catalyst bed temperature, and after the initial target catalyst bed temperature setting period Target catalyst bed temperature setting means for setting the target catalyst bed temperature during regeneration as the target catalyst bed temperature;
Initial target catalyst bed temperature setting period learning means for learning a heating adjustment amount correction value corresponding to the difference between the heating adjustment amount and the actual heating amount within the initial target catalyst bed temperature setting period;
Catalyst bed temperature detecting means for detecting the actual catalyst bed temperature of the catalyst regeneration filter;
While controlling the heating adjustment amount based on the difference between the target catalyst bed temperature set by the target catalyst bed temperature setting means and the actual catalyst bed temperature detected by the catalyst bed temperature detection means, the initial target catalyst After the heating adjustment amount correction value is learned by the bed temperature setting period learning means, the heating control amount is controlled using the heating adjustment amount correction value together with the difference between the target catalyst bed temperature and the actual catalyst bed temperature. Adjustment amount control means;
A catalyst bed temperature control device comprising: 2. The initial target catalyst bed temperature setting according to claim 1, further comprising proportional control means for controlling a heating adjustment amount based on a difference between the target catalyst bed temperature and the actual catalyst bed temperature at an initial stage of the initial target catalyst bed temperature setting period. The catalyst bed temperature control device, wherein the period learning means learns the heating adjustment amount correction value after the control by the proportional control means is completed. 3. The catalyst bed temperature control according to claim 1, wherein the heating adjustment amount is an adjustment amount of fuel added to the exhaust gas, and the actual heating amount is a fuel amount actually added to the exhaust gas. apparatus. 4. The catalyst bed temperature control device according to claim 3, wherein the amount of fuel added to the exhaust gas is adjusted by adjusting the post injection amount performed in the combustion chamber of the internal combustion engine. 4. The catalyst bed temperature control apparatus according to claim 3, wherein the amount of fuel added to the exhaust gas is adjusted by adjusting the fuel addition amount performed by a fuel addition valve provided in the exhaust path. The target catalyst bed temperature setting means according to any one of claims 1 to 5, wherein after the initial target catalyst bed temperature setting period, the target catalyst bed temperature is gradually changed from the initial target catalyst bed temperature to the regeneration target catalyst bed temperature. The catalyst bed temperature control apparatus characterized by making it transfer. 7. The heating adjustment amount control means according to claim 1, wherein the heating adjustment amount control means controls the heating adjustment amount in a state where learning of the heating adjustment amount correction value is continued after the initial target catalyst bed temperature setting period. A catalyst bed temperature control device characterized by. The heating adjustment amount correction value according to any one of claims 1 to 6, wherein the heating adjustment amount control means is learned by the initial target catalyst bed temperature setting period learning means after the initial target catalyst bed temperature setting period. The catalyst bed temperature control apparatus, wherein the heating adjustment amount is controlled in a state where the temperature is fixed. 9. The catalyst bed temperature control apparatus according to claim 1, wherein the heating adjustment amount correction value obtained by learning is an integral control amount in catalyst bed temperature feedback control. In any one of Claims 1-9, the upper limit setting means which restrict | limits the said heating adjustment amount by setting the upper limit of the said heating adjustment amount,
Upper limit changing means for correcting the upper limit value set by the upper limit setting means according to the magnitude of the heating adjustment amount correction value;
A catalyst bed temperature control device comprising: 11. The catalyst bed temperature control apparatus according to claim 10, wherein the upper limit changing unit performs addition correction for adding the heating adjustment amount correction value to the upper limit value set by the upper limit setting unit. In any one of Claims 1-11, the said target catalyst bed temperature setting means sets the said initial target catalyst bed temperature setting period by the elapsed time from the time of the control start by the said heating adjustment amount control means. A catalyst bed temperature control device. 12. The target catalyst bed temperature setting means according to claim 1, wherein the target catalyst bed temperature setting means sets the initial target catalyst bed temperature setting period from the start of control by the heating adjustment amount control means to the initial target catalyst bed temperature setting period learning means. The catalyst bed temperature control apparatus is characterized in that the time until the fluctuation of the heating adjustment amount correction value learned by the step becomes smaller than the reference fluctuation range. The stable operation state detection means for detecting a stable operation state of the internal combustion engine according to any one of claims 1 to 13, wherein the initial target catalyst bed temperature setting period learning means is configured to detect the internal combustion engine by the stable operation state detection means. Only when it is determined that the engine is in a stable operation state, learning of the heating adjustment amount correction value is executed. 14. The regeneration request operation detecting means for detecting a regeneration request operation from a driver of the internal combustion engine in a stable operation state of the internal combustion engine according to any one of claims 1 to 13, wherein the initial target catalyst bed temperature setting period learning means includes the The catalyst bed temperature control apparatus, wherein learning of the heating adjustment amount correction value is executed only when the regeneration request operation is detected by the regeneration request operation detecting means. 16. The catalyst bed temperature control device according to claim 15, wherein the stable operation state of the internal combustion engine is an idle operation state.

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