JP2006097623A - Diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a diesel smoke purification means from being over-heated at the initial stage of the starting of an engine and also suppress the deterioration of fuel economy. <P>SOLUTION: A start period determination part is installed in a regenerative treatment means regenerating a diesel smoke purification means. The start period determination part determines a passed time T after the start of an engine proper. Also, a prohibiting part for prohibiting the execution of a filter regenerative treatment until the determined passed time reaches a pre-set start reference value Tstd or higher is installed therein. Immediately after the start of the engine when a large amount of fuel is jetted, an excessive regenerative treatment can be avoided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a diesel engine, and more particularly to a diesel engine that has a catalytic function and employs diesel smoke purification means that collects diesel smoke exhaust particulates.

  The exhaust gas discharged from the diesel engine includes diesel smoke due to free carbon generated during combustion. In order to collect the particulate matter that causes the diesel smoke, the exhaust system of the diesel engine is provided with a diesel smoke purification means that has a catalytic function and collects exhaust smoke fine particles of the diesel smoke.

As a method for regenerating the diesel smoke purification means, as shown in Patent Document 1, unburned fuel is supplied to the exhaust system at a predetermined timing, and fuel supplied by the oxidation function by the catalytic function of the diesel smoke purification means is used. A configuration is known in which the diesel smoke purification means is regenerated with the heat of combustion.
Japanese Patent Laid-Open No. 08-042326

  However, since a large amount of fuel is injected at the time of starting in a diesel engine, unburned fuel flows out to the exhaust system, and mist-like unburned fuel adheres to the diesel smoke purification means, or diesel smoke purification means In some cases, the unburnt fuel is filled in the exhaust passage upstream of the exhaust gas. For this reason, if unburned fuel for regeneration is supplied to the diesel smoke purification means immediately after the engine is started, the temperature of the exhaust gas flowing into the diesel smoke purification means rises, and combustion with unburned fuel that has flowed into the exhaust system first In combination with the combustion of the exhaust particulates, there may be a problem that the diesel smoke purification means is excessively heated.

  The present invention has been made to solve the above-described problems, and provides a diesel engine that can prevent excessive temperature rise of diesel smoke purification means in the initial stage of engine start and can suppress a decrease in fuel consumption. It is an issue.

  In order to solve the above problems, the present invention provides a diesel smoke purification means having a catalytic function and collecting diesel smoke exhaust particulates, an engine body for discharging exhaust gas to the diesel smoke purification means, and the engine A fuel injection device provided in each cylinder of the main body, a fuel injection control means for controlling at least the fuel injection amount and fuel injection timing of the fuel injection device, and collection of exhaust particulates collected by the diesel smoke purification means When the collected exhaust particulate amount detecting means for detecting the exhaust particulate amount and the collected exhaust particulate amount detected by the collected exhaust particulate amount detecting means are equal to or greater than a preset regeneration start threshold, unburned fuel is In order to supply to the exhaust system, the fuel injection device performs post-injection to inject fuel between the expansion stroke and the exhaust stroke, and reaches below the regeneration end threshold. A regeneration processing means for controlling the fuel injection control means to stop the post-injection, wherein the regeneration processing means determines an elapsed time after starting the engine body. And a prohibition unit for prohibiting execution of the filter regeneration process by the regeneration processing unit until the elapsed time determined by the start period determination unit reaches a preset start reference value or more. It is a diesel engine characterized by

  In this aspect, when the regeneration processing means regenerates the diesel smoke purification means based on the collected exhaust particulate amount detected by the collected exhaust particulate quantity detection means, first, the elapsed time after starting the engine body is a start period determination unit. Is determined by The prohibiting unit prohibits execution of the filter regeneration processing by the regeneration processing means until the elapsed time has passed the preset initial start period, so immediately after the engine is started in which a large amount of fuel is injected. In this case, it is possible to avoid excessive reproduction processing.

  In a preferred aspect, the diesel smoke purification means includes a particulate filter that collects exhaust particulates discharged from the engine, and an oxidation catalyst that is disposed upstream of the particulate filter in the exhaust passage. In this embodiment, the particulate filter is preferably coated with a catalyst. On the other hand, when a particulate filter coated with a catalyst is employed, the oxidation catalyst can be omitted.

  In another aspect, the regeneration processing means includes a start reference value changing unit that changes the start reference value to be longer as the injection amount of fuel injected for engine operation is larger. In this aspect, since the starting reference value can be changed long using the fuel injection amount for operating the engine as a parameter, control based on the fuel injection amount can be performed.

  In yet another aspect, the engine further comprises exhaust temperature detection means for detecting the exhaust temperature of the engine, and the regeneration processing means changes the start reference value longer as the exhaust temperature detected by the exhaust temperature detection means is lower. Has a change section.

  In this aspect, since the start reference value can be changed using the exhaust gas temperature as a parameter, control based on the fuel injection amount can be performed. The exhaust gas temperature detecting means is preferably embodied by providing a temperature sensor in the diesel smoke purification means. However, the method is not limited to this example, and a method of indirectly estimating the temperature of the diesel smoke purification means may be employed. Further, the start reference value changing unit may change the start reference value to be longer as the amount of fuel injected for engine operation is larger.

  As described above, according to the present invention, the execution of the filter regeneration process by the regeneration processing means is prohibited until the preset start reference value has elapsed, so that the engine is started when a large amount of fuel is injected. Immediately after, it is possible to avoid the excessive regeneration process from being executed, and it is possible to prevent the diesel smoke purification means from excessively rising in the initial stage of engine start.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a schematic configuration of a diesel engine 10 according to an embodiment of the present invention.

  With reference to the figure, the illustrated diesel engine 10 includes an engine body 20. The engine body 20 integrally includes a cylinder block 22 that rotatably supports the crankshaft 21 and a cylinder head 23 that is disposed above the cylinder block 22. The cylinder block 22 is provided with a water jacket 22a.

  The cylinder block 22 is provided with a plurality of cylinders 24. Each cylinder 24 is provided with a piston 25 connected to the crankshaft 21 and a combustion chamber 26 formed in the cylinder 24 by the piston 25 in the same manner as a known configuration. The cylinder block 22 of the engine body 20 is provided with a water temperature sensor 27 for detecting the water temperature of the water jacket 22a and a crank angle sensor 28 for detecting the rotation speed of the crankshaft 21.

  In order to inject fuel into each combustion chamber 26, the engine body 20 is provided with a common rail fuel injection system 30. The common rail fuel injection system 30 is provided for each combustion chamber 26, and includes an injector 31 for injecting fuel, a common rail 32 to which each injector 31 is connected, a pressure regulator 33 provided for the common rail 32, and a pressure. A pressure sensor 34 for controlling the regulator 33, a high-pressure pump 35 connected to the common rail 32, and a fuel tank (not shown) for storing fuel injected from the injector 31 via the common rail 32 by the high-pressure pump 35 Have. The detailed configuration of the common rail fuel injection system 30 is similar in principle to that disclosed in, for example, Patent Document 1, and thus the details thereof are omitted. In the present embodiment, the common rail fuel injection system 30 has the same configuration. By adopting the system 30, the fuel injection timing and injection pressure from each injector 31 can be freely set.

  The cylinder 24 of the engine body 20 is provided with an intake system 40 that supplies fresh air to the combustion chamber 26 and an exhaust system 50 that exhausts burnt gas burned in the combustion chamber 26 of the cylinder 24. .

  An intake filter 42, an intercooler 43 disposed downstream of a turbocharger 76, which will be described later, and an intake manifold 44 are connected to the intake path 41 of the intake system 40 in this order from the upstream side. The outside air is supplied from 44 to the cylinder 24 via a branch intake passage 45 provided for each combustion chamber 26. 41a is a throttle valve provided between the intercooler 43 and the intake manifold 44, and the amount of intake air supplied from the intake passage 41 to the intake manifold 44 is controlled by the throttle valve 41a. ing. Each branch intake passage 45 is provided with an intake valve 46. Further, the intake path 41 is provided with an intake air amount sensor 47 provided at the downstream end of the intake filter 42, and an intake air temperature sensor 48 and an intake pressure sensor 49 provided between the intercooler 43 and the intake manifold 44. ing.

  The exhaust system 50 includes a branch exhaust passage 51 communicating with the combustion chamber 26, an exhaust valve 52 provided for each branch exhaust passage 51, an exhaust manifold 53 provided on the downstream side of the exhaust valve 52, and the exhaust Diesel smoke purification means 60 provided on the downstream side of the manifold 53 is provided.

  The diesel smoke purification means 60 has a catalytic function and is for collecting exhaust smoke particulates of diesel smoke. Specifically, the diesel smoke purification means 60, specifically, a catalyst disposed on the downstream side of the oxidation catalyst 61. It is comprised by the curate filter unit 62. The particulate filter unit 62 has a particulate filter 63 coated with a catalyst. The diesel smoke purification means 60 is not limited to this example, and the oxidation catalyst 61 is omitted, or the particulate filter unit having a filter not coated with the catalyst and the oxidation catalyst 61 is combined. Also good. The diesel smoke purification means 60 includes exhaust temperature sensors 65, 66, and 67 disposed upstream and downstream of the oxidation catalyst 61 and downstream of the particulate filter unit 62, and upstream and downstream of the particulate filter unit 62. Exhaust pressure sensors 68 and 69 arranged on the side, and an oxygen concentration sensor 70 as oxygen concentration detection means arranged on the downstream side of the particulate filter unit 62 are provided.

  Among these, the exhaust gas temperature sensor 66 constitutes an exhaust gas temperature detecting means for detecting the exhaust gas temperature in the present embodiment.

  The intake valves 46 and the exhaust valves 52 of the intake system 40 and the exhaust system 50 are respectively driven by control of the ECU 100 (described later) by a valve opening / closing mechanism (not shown), thereby corresponding branch intake passages 45 and 51 at predetermined timings. Is configured to open and close.

  In the illustrated diesel engine 10, an EGR system 75 and a turbocharger 76 are provided between the intake system 40 and the exhaust system 50. Since these are basically the same as the known configurations, the description thereof is omitted.

  In order to control each part of the diesel engine 10, the diesel engine 10 is provided with an ECU 100.

  The ECU 100 includes a CPU 101, a memory 102, an input / output device 103, and a bus 104 that electrically connects them.

  The memory 102 has a ROM for storing a program and parameters for controlling the operation of the diesel engine 10 and a RAM serving as a storage area for data processing. In the illustrated embodiment, a non-volatile memory 105 is provided in the memory 102. By providing a storage area for predetermined data and parameters in the non-volatile memory 105, a flowchart described later can be realized. ing.

  The input / output device 103 includes a water temperature sensor 27 and a crank angle sensor 28 of the engine body 20, a pressure sensor 34 provided on the common rail 32 of the common rail fuel injection system 30, an intake air amount sensor 47 of the intake system 40, an intake air The temperature sensor 48 and the intake pressure sensor 49 are connected to exhaust temperature sensors 65, 66, 67, exhaust pressure sensors 68, 69, and an oxygen concentration sensor 70 provided in the diesel smoke purification means 60 (FIG. 2). reference). Further, in order to detect the travel distance of the vehicle, the trip meter 80 is connected so that a signal (filter life determination value) D output to the trip meter 80 is input.

  FIG. 2 is a block diagram of the ECU 100 according to the embodiment of FIG.

  Referring to the figure, ECU 100 functionally includes an operation control means 110 for controlling the operation of engine body 20 and a fuel injection control means 120 for performing fuel injection control, as well as diesel smoke purification means 60. The reproduction processing means 140 for performing the reproduction processing is functionally configured.

  In order to operate the engine body 20, the operation control unit 110 operates the fuel injection amount Q and fuel injection timing of the common rail fuel injection system 30, the opening degree of the throttle valve 41 a of the intake system 40, the intake valve 46 and the exhaust valve 52. It controls the opening and closing timing, the valve opening and closing operation of the EGR system 75, and the like.

  The fuel injection control means 120 receives the detection signal of the pressure sensor 34 of the common rail fuel injection system 30 based on the control of the operation control means (not shown), and injects fuel injected from the injector 31 of the common rail fuel injection system 30. It controls the timing and injection amount.

Based on the value of the filter regeneration flag F set in the data area of the memory 102, the regeneration processing means 140 drives the fuel injection control means 120 at a predetermined timing separately from the control by the operation control means, and the diesel smoke purification The fuel injection is performed to regenerate the particulate filter 63 of the means 60 (referred to as “post-injection” in this embodiment), and the amount M of exhaust particulate collected by the particulate filter 63 is estimated. The collection amount estimation unit 141, the use period determination unit 142 that determines the use period of the diesel smoke purification means 60, and the threshold values M _α , M _β , and M _γ for updating the filter regeneration flag F are set under predetermined conditions. A threshold value changing unit 143 to be changed, a starting period determining unit 144 for determining a starting period of the diesel engine 10, and starting The starting reference value T _std as a criterion between the determination unit 144 and the start value change unit 145 for changing a predetermined condition, and a prohibition unit 146 prohibits filter regeneration process when the predetermined has functionally Yes.

  First, the collection amount estimation unit 141 will be described with reference to FIG. FIG. 3 is a characteristic diagram showing the relationship between the differential pressure used for controlling the regeneration processing means 140 shown in FIG. 2 and the amount of fine particles.

  Referring to FIG. 3, the amount M of fine particles collected by the particulate filter 63 has a correlation with the filter front-rear differential pressure ΔP between the upstream side and the downstream side of the particulate filter 63. In the present embodiment, the correlation is accumulated by experiment or the like to derive the characteristic A and is registered in the memory 102 as a map. The collection amount estimation unit 141 calculates a filter front-rear differential pressure ΔP between the upstream side and the downstream side of the particulate filter 63 based on the detection signals of the exhaust pressure sensors 68 and 69, and based on the calculated value, The amount M of collected exhaust particulate matter collected by the particulate filter 63 is estimated from a map registered in the memory 102 in advance.

The usage period determination unit 142 compares the initial state reference value D _std stored in advance in the non-volatile memory 105 with the travel distance value output from the trip meter 80 as a filter life determination value D. The use period of the curate filter 63 is determined. The initial state reference value D _std is set based on experimental data in advance for the period until the particulate filter 63 becomes familiar with the state of the characteristic A from the state of the characteristic B1 in FIG. Is stored in the non-volatile memory 105. The filter life determination value D is also a value that is accumulated and used by being stored in the nonvolatile memory 105. When the particulate filter 63 is newly installed, that is, when the vehicle is in a green state, the filter life determination value D is set to zero. Further, each time the particulate filter 63 is replaced, a dealer or the like uses a diagnostic device (external control means) 64 (shown in a block in FIG. 2) to set the filter life judgment value D of the particulate filter 63 to 0. Reset to. Thus, the ECU 100 functionally configures the use period determination unit 142 and can determine the use period of the diesel smoke purification means 60.

The threshold value changing unit 143 changes the values of the reproduction start threshold value M _α and the reproduction end threshold value M _β for the reproduction processing unit 140 to start reproduction processing based on a flow described later. With reference to FIG. 3, the regeneration start threshold value M _α is a threshold value for starting the regeneration of the particulate filter 63. The reproduction end threshold value _Mβ is a threshold value for ending the reproduction process. Here, in this embodiment, when it is determined the value slightly greater than the reproduction end threshold value M _beta has a playback end threshold M _gamma of initial filter, the particulate filter 63 to be a predetermined initial state, this The reproduction process is controlled using the threshold value _Mγ . As shown in the figure, the magnitude relationship of each threshold value M _α , M _β , M _γ is
M _α > M _γ > M _β
It has become.

More specifically, referring to FIG. 3, for example, when the particulate filter 63 is new, it takes a characteristic such as B1 due to the influence of oil or the like adhering to the particulate filter 63. There is a case. In this case, when the collected exhaust particulate amount M is calculated only by the differential pressure ΔP before and after the filter, regeneration processing control frequently occurs at an initial stage where the collected exhaust particulate amount M is relatively small. Therefore, in the present embodiment, the use period determination unit 142 determines the filter life determination value D of the particulate filter 63 in order to consider the characteristics of the particulate filter 63 in the initial state, and the filter of the diesel smoke purification means 60 When the life determination value D does not exceed the predetermined initial state reference value D _std , the threshold value changing unit 143 sets the value of the reproduction end threshold value M _β stored in the memory 102 to M _γ high. Yes.

Next, the start period determination unit 144 determines whether or not a count value (elapsed time after engine start) T counted when the diesel engine 10 starts operation is equal to or greater than a preset start reference value T _std. It is for judging. In the initial operation state of the diesel engine 10, more fuel is injected during operation than the catalyst activity of the particulate filter 63, so that unburned fuel remains in the particulate filter 63 in a mist state. When post-injection is performed, excessive combustion occurs in the particulate filter 63 due to the combination of the remaining unburned fuel and exhaust particulate matter, and in order to avoid this, the unreacted remaining in the particulate filter 63 A start-up period determination unit 144 is provided for determining a period until the fuel is evaporated and discharged from the particulate filter 63. In a predetermined case, the regeneration process is prohibited by the prohibition unit 146.

The start reference value changing unit 145 is for optimizing the combustion of the post-injected fuel by changing the start reference value T _std under a predetermined condition.

  The prohibition unit 146 is for prohibiting the filter regeneration processing by updating the filter regeneration flag F to 0 by a predetermined control logic.

  FIG. 4 is a flowchart showing the flow of filter regeneration processing in the embodiment of FIG.

  Referring to the figure, when engine operation is started, ECU 100 initializes count value T and 0 for filter regeneration flag F to 0 in the data memory area, respectively. Store (step S1).

Next, in the present embodiment, the ECU 100 executes a setting control subroutine for setting a starting reference value T _std to be compared with the count value T (step S2). By this step S2, the starting reference value T _std is determined. By executing this subroutine, the ECU 100 functionally configures the start reference value changing unit 145 and can set the start reference value T _std suitable for the operating state of the diesel engine 10.

Next, the start period determination unit 144 of the ECU 100 compares the determined start reference value T _std with the count value T, and the particulate filter regeneration determination process until the count value T becomes equal to or greater than the start reference value T _std. (Step S3) is reserved. By this step S3, the ECU 100 prohibits the regeneration processing means from executing the filter regeneration process until the count value (elapsed time) T detected by the start period determination unit 144 has passed the preset start reference value _Tstd. The prohibiting portion is configured functionally so as to avoid excessive regeneration processing immediately after the engine is started when a large amount of fuel is injected.

When the count value T reaches the start reference value T _std , the process proceeds to the particulate filter regeneration determination processing subroutine (step S10). In this subroutine, as will be described in detail later, it is determined whether or not a filter regeneration process should be performed. If it is determined that regeneration is necessary, the value of the filter regeneration flag F is updated to 1. Further, when the filter regeneration flag F set to 1 is set to 0 under a predetermined condition, the regeneration processing is prohibited regardless of the collected exhaust particulate amount M.

  When the subroutine of step S10 ends, the filter regeneration flag F is referred to (step S11), and when the filter regeneration flag F is updated to 1, post injection is performed (step S20), and the process proceeds to step S10. In this post-injection, the ECU 100 causes the common rail fuel injection system 30 to execute fuel injection for operating the engine main body 20, and then drives the common rail fuel injection system 30 again from the injector 31 between the expansion stroke and the exhaust stroke. This is done by injecting fuel.

  On the other hand, when the filter regeneration flag F is 0, the process proceeds to step S10 without performing the post-injection. By executing these steps S1 to S20, the ECU 100 functionally configures the regeneration processing unit 140 or the prohibition unit 146 of the regeneration processing unit 140, executes post-injection at an appropriate timing, and the diesel smoke purification unit 60. Can be reproduced.

FIG. 5 is a flowchart showing a control flow of a setting control subroutine for setting the start reference value T _std in the flowchart of FIG.

Referring to the figure, when the control shifts to the setting control of starting reference value T _std , first, ECU 100 detects exhaust gas temperature Tp based on the output of exhaust gas temperature sensor 66 (step S21) and operates engine body 20. The fuel injection amount Q injected for this purpose is referred to (step S22).

Next, based on the setting map recorded in the memory 102, the start reference value _Tstd is set longer as the fuel injection amount Q increases (step S23). As a result, regeneration processing is prohibited at the initial start of the engine having a relatively large fuel injection amount Q, and the start reference value T _std for determining the initial start of the engine is increased in proportion to the fuel injection amount Q. Therefore, it is possible to more reliably prevent excessive combustion of the particulate filter 63 due to post-injection, and suppress reduction in fuel consumption.

Further, in this step S23, the exhaust gas temperature Tp detected in step S21 is associated, and the lower the exhaust gas temperature Tp, in other words, the more the unburned fuel remaining in the diesel smoke purification means 60 is less likely to evaporate. The start reference value T _std is corrected to be longer. As a result, the regeneration process is prohibited even at a low temperature at which the catalytic reaction is unlikely to occur, so that it is possible to prevent unburned fuel from remaining in the diesel smoke purification means 60 and causing excessive combustion.

  Next, the particulate filter regeneration determination processing subroutine in step S10 will be described with reference to FIG. FIG. 6 is a flowchart of the particulate filter regeneration determination processing subroutine in the main flow of FIG.

  Referring to the figure, when the particulate filter regeneration determination processing subroutine of step S10 is executed, ECU 100 determines the upstream side and downstream side of particulate filter 63 based on the detection signals of exhaust pressure sensors 68 and 69. Is calculated (step S102). Next, based on the calculated value, the collected exhaust particulate amount M collected by the particulate filter 63 is estimated from the map based on FIG. 3 registered in advance in the memory 102 (step S103). By these steps S102 and S103, the ECU 100 functionally configures the collection amount estimation unit 141 and can specify the collected exhaust particulate amount M collected by the particulate filter 63.

Next, in order to determine whether or not the particulate filter 63 is in the initial state, the ECU 100 sets the travel distance value output from the trip meter 80 as the filter life determination value D in the nonvolatile memory 105 in advance. The stored initial state reference value _Dstd is compared (step S104).

If when the filter life determination value D is equal to or less than the initial state reference value D _std, ECU 100 determines that the particulate filter 63 is in the initial state, reproducing the reproduction end threshold M _beta slightly higher initial filter than that value updating the end threshold value M _gamma (step S105). By these processes, the ECU 100 functionally configures the usage period determination unit 142 and the threshold value changing unit 143, and can execute the regeneration process determination in accordance with the usage state of the particulate filter 63.

Next, ECU 100, corresponding to the map based on the characteristic diagram of FIG. 3, the trapped exhaust particulates amount M calculated in step S103 wherein it is determined whether or not the reproduction start threshold M _alpha or (step S106) . If when trapped exhaust particulate amount M is equal to the reproduction start threshold M _alpha above, ECU 100 updates the filter regeneration flag F stored in the memory area 1 (step S107), and returns to the main routine.

On the other hand, if less than the regeneration start threshold M _alpha, further trapped exhaust particulates amount M is compared with the reproduction end threshold M _beta (step S108). In this step S108, if the case trapped exhaust particulate amount M is equal to the reproduction end threshold M _beta least, ECU 100 returns to the main routine without updating the filter regeneration flag F. Therefore, by repeating the particulate filter regeneration determination processing subroutine, the regeneration processing is repeated when the filter regeneration flag F is 1, and the regeneration processing is not started when the filter regeneration flag F is 0. . As a result, while the regeneration process is not started until the exhaust particulate amount M reaches the regeneration initiation threshold M _alpha, playback processing is not performed. On the other hand, after the once reproduction process is started, the collection to the exhaust particulate amount M is equal to or less than regeneration termination threshold M _beta, so that the regeneration process is continued.

Further, in step S108, if it is assumed less than trapping exhaust particulate amount M reproduction ending threshold M _beta, ECU 100 is a filter regeneration flag F is updated to 0 (step S109) the flow returns to the main routine.

Here, in the present embodiment, in step S104, the lifetime of the particulate filter 63 is determined. If the particulate filter 63 is in the initial state, the regeneration end threshold value _Mβ is the initial value shown in FIG. Since the filter is changed to the regeneration end threshold value M _γ (step S105), it is possible to substantially reduce the period or degree of execution of the regeneration process and avoid applying excessive regeneration processing to the particulate filter 63. It becomes possible.

As described above, according to the present embodiment, the regeneration processing unit 140 detects the collected exhaust particulate amount detected by the exhaust pressure sensors 68 and 69 and the collected amount estimation unit 141 as the collected exhaust particulate amount detection unit. In regenerating the diesel smoke purification means 60 based on M, first, the use period determination unit 142 specifies the filter life determination value D of the particulate filter 63 of the diesel smoke purification means 60, and the state of the diesel smoke purification means 60 is determined. It is determined whether or not it is in an initial state. Since the threshold value changing unit 143 can change the threshold value M _α for setting the start or end of the regeneration process according to the usage state of the diesel smoke purification means 60, detection of the trapped amount of exhaust particulates due to the influence of impurities. Even in the diesel smoke purification means 60 in the initial stage of use where the inaccuracy becomes inaccurate, it is possible to avoid the excessive regeneration process being performed.

In the present embodiment, the elapsed time after the engine main body is started is determined by the start period determination unit 144 as the count value T, and the prohibition unit 146 is configured to perform the initial start with the count value (elapsed time) T set in advance. The execution of the filter regeneration process by the regeneration processing unit 140 is prohibited until the reference value T _std as the period elapses, so that an excessive regeneration process is performed immediately after the engine is started when a large amount of fuel is injected. Can be avoided.

  Further, in the present embodiment, there is further provided an exchange detection means (diagnostic device 64, use period determination unit 142) that detects the replacement of the particulate filter 63 and gives an initial value to the use period determination unit 142 of the regeneration processing unit 140. I have. Therefore, even when the particulate filter 63 is replaced, this can be detected reliably, and the filter regeneration process can be executed on the replaced particulate filter 63 under appropriate regeneration conditions.

Further, in the present embodiment, the regeneration processing unit 140 includes a start reference value changing unit 145 that changes the start reference value T _std as the amount of fuel injected for engine operation increases. The starting reference value T _std can be changed long using the fuel injection amount for operating the engine as a parameter, and control based on the fuel injection amount can be performed.

Further, in the present embodiment, an exhaust temperature sensor 66 as exhaust temperature detecting means for detecting the exhaust temperature of the engine is further provided, and the start reference value changing unit 145 of the regeneration processing means 140 is an exhaust gas detected by the exhaust temperature detecting means. since temperature changes lower the longer the start reference value T _std, as the exhaust temperature parameter, the starting reference value T _std can change, it is possible to perform control based on the fuel injection amount.

  As described above, according to the present embodiment, it is possible to determine whether or not the diesel smoke purification means 60 is in the initial state and change the degree of the regeneration process. There is a remarkable effect that it is possible to prevent overheating of the means 60 and to suppress a decrease in fuel consumption.

Further, the filter regeneration process by the regeneration processing unit 140 is prohibited until the preset start reference value T _std has elapsed, and therefore, excessive regeneration immediately after engine start when a large amount of fuel is injected. It becomes possible to avoid the processing being executed, and there is a remarkable effect that it is possible to prevent an excessive increase in temperature of the diesel smoke purification means in the initial stage of engine start.

  The above-described embodiments are merely preferred specific examples of the present invention, and the present invention is not limited to the above-described embodiments. Another embodiment of the present invention will be described below.

  First, referring to FIG. 3, when the particulate filter 63 is new, the filter front-rear differential pressure ΔP and the exhaust particulate amount M have characteristics such as B1, for example. By executing the process, the differential pressure ΔP before and after the filter based on the detection signals of the exhaust pressure sensors 68 and 69 exhibits a characteristic indicated by B2, for example, so as to follow the characteristic A of the particulate filter 63 from which impurities are eliminated earlier. become. Therefore, in the embodiment shown in FIG. 7 and the subsequent figures, a particulate filter tuning mode in which the particulate filter 63 in the initial state is positively subjected to a regeneration process to change the particulate filter 63 from the initial state to the state of the characteristic A. The structure provided is shown.

  FIG. 7 is a flowchart according to another embodiment of the present invention.

With reference to the figure, in the control flow according to this embodiment, when the diesel engine 10 exceeds the start reference value _Tstd in step S3, first, it is determined whether or not the particulate filter 63 is in the initial state. If it is determined (step S4) and it is determined that it is in the initial state, the particulate filter tuning processing subroutine is executed (step S5), and after the post injection (step S20), the process proceeds to step S4. However, it is different from the embodiment shown in FIG.

  FIG. 8 is a subroutine showing a control flow of the particulate filter tuning process subroutine of FIG.

Referring to the figure, when the particulate tuning process is executed, the amount of collected exhaust particulates M collected by the particulate filter 63 is calculated (steps S51 and S52). The ECU 100 changes the value to a value obtained by subtracting the predetermined value κ from the regeneration start threshold value M _α (step S53). As a result, the frequency at which the filter regeneration process is started increases. Incidentally, in this step S53, it is preferable to change the playback end threshold value M _beta finished playing threshold M _gamma of the initial filter. In this case, the tuning process can be completed in a short period of time, and the excessive filter regeneration process can be avoided.

Thereafter, the collection exhaust particulate amount M calculated are compared has been the reproduction start threshold value M _alpha correction, trapped exhaust particulates amount M is equal to the playback start threshold M _alpha above, the filter regeneration flag F to 1 (Step S55) Next, an initial state reference value _Dstd for determining the lifetime of the particulate filter 63 is subtracted by a predetermined value N (Step S56). By this subtraction process, it is possible to avoid performing the tuning process on the particulate filter 63 that has been removed from the initial state by the tuning process.

On the other hand, if the calculated collected exhaust particulate amount M is less than the corrected regeneration start threshold value M _α in step S54, the collected exhaust particulate amount M is further compared with the regeneration end threshold value M _β (step S57). ), if the trapped exhaust particulate amount M is greater than the regeneration end threshold value M _beta, ECU 100, while returns to the main routine without updating the filter regeneration flag F, trapped exhaust particulates amount M reproduction ending threshold M _beta If it falls below the threshold value, the filter regeneration flag F is updated to 0 (step S58). As described above, in the embodiment shown in FIG. 7, when it is determined that the diesel smoke purification means 60 is in the initial use state, the regeneration process is performed in the tuning process mode in which the regeneration start threshold value M _α is lowered. The earlier the start, the shorter the processing period, and it is possible to stabilize the diesel smoke purification means 60 from a transient initial state while avoiding excessive regeneration processing.

  In addition, when employ | adopting the said particulate filter tuning process, you may perform the process shown in FIG. FIG. 9 is a subroutine showing a control flow of another aspect in the particulate filter tuning processing subroutine of FIG.

Referring to the drawing, in the illustrated embodiment, first, whether the particulate filter 63 is used preset period D _N is determined (step S501), if used, the particulate filter 63 trapped regardless exhaust particulate amount M of, and updates the filter regeneration flag F to 1, when the filter life judgment value D is less than the period D _N, the processing particulate filter regeneration determination process (FIG. 7 You may make it change to step S10).

  In this case, by making the reproduction frequency frequent, the characteristics of the particulate filter 63 can be adjusted to the characteristics A in FIG. 3 at an early stage.

  In this embodiment, the diesel smoke purification means 60 is tuned regardless of the amount M of exhaust particulates collected and exhausted. Therefore, the diesel smoke purification means 60 can be stabilized earlier by that amount.

In embodying the above-described embodiments, a storage area for counting the number of reproductions is provided in the non-volatile memory, and while the particulate filter 63 is determined to be in the initial state, the number of reproductions is integrated. As the number of playbacks increases, the playback end threshold value _Mβ may be lowered (for example, the first playback end is 4 g / l, the second playback end is 3.5 g / l...). In that case, the particulate filter 63 becomes familiar with the characteristic A as the reproduction is performed, and therefore it is possible to avoid an excessive reproduction process.

  Further, when the embodiment of FIG. 7 is adopted, as shown in FIG. 10, the particulate regeneration determination process may be changed to a simple flow in which steps S104 and S105 in FIG. 6 are omitted.

  It goes without saying that various modifications can be made within the scope of the claims of the present invention.

It is a figure showing the schematic structure of the diesel engine concerning one embodiment of the present invention. It is a block diagram of ECU which concerns on embodiment of FIG. It is a characteristic view which shows the relationship between the differential pressure used for control of the reproduction | regeneration processing means shown in FIG. It is a flowchart which shows the flow of the filter reproduction | regeneration processing in embodiment of FIG. FIG. 5 is a flowchart showing a control flow of a setting control subroutine for setting an initial start time in the flowchart of FIG. 4. FIG. 5 is a flowchart of a particulate filter regeneration determination processing subroutine in the main flow of FIG. 4. 6 is a flowchart according to another embodiment of the present invention. It is a subroutine which shows the control flow of the particulate filter tuning process subroutine of FIG. It is a subroutine which shows the control flow of another aspect in the particulate filter tuning processing subroutine of FIG. It is a subroutine which shows the control flow of another aspect in the particulate filter reproduction | regeneration determination subroutine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diesel engine 20 Engine main body 24 Cylinder 60 System 60 Diesel smoke purification means 61 Oxidation catalyst 62 Particulate filter unit 63 Particulate filter 66 Exhaust temperature sensor (an example of exhaust temperature detection means)
68 Exhaust pressure sensor (an example of collected amount detection means)
69 Exhaust pressure sensor (an example of collected amount detection means)
100 ECU
110 Operation Control Unit 120 Fuel Injection Control Unit 140 Regeneration Processing Unit 141 Collected Amount Estimating Unit 144 Start Period Determination Unit 145 Start Reference Value Changing Unit 146 Prohibited Unit F Filter Regeneration Flag M Collected Exhaust Particle Size M _α Regeneration Start Threshold M _β Regeneration end threshold M Regeneration end threshold Q in _γ initial filter Fuel injection amount T Count value (elapsed time after engine start)
Tp Exhaust temperature T _std Start reference value ΔP Differential pressure across filter

Claims (5)

Diesel smoke purification means having a catalytic function and collecting diesel smoke exhaust particulates;
An engine body for discharging exhaust gas to the diesel smoke purification means;
A fuel injection device provided in each cylinder of the engine body;
Fuel injection control means for controlling at least the fuel injection amount and the fuel injection timing of the fuel injection device;
The collected exhaust particulate amount detection means for detecting the collected exhaust particulate amount of the exhaust particulate collected by the diesel smoke purification means;
When the collected exhaust particulate quantity detected by the collected exhaust particulate quantity detection means is greater than or equal to a preset regeneration start threshold, the fuel injection device exhausts from the expansion stroke to supply unburned fuel to the exhaust system. A diesel engine comprising post-injection for injecting fuel during a stroke and regeneration processing means for controlling the fuel injection control means to stop the post-injection when the fuel injection is less than a regeneration end threshold value Because
The reproduction processing means includes
A start period determination unit for determining an elapsed time after the start of the engine body,
A diesel engine having a prohibition unit that prohibits execution of filter regeneration processing by the regeneration processing means until an elapsed time determined by the start period determination unit reaches a preset start reference value or more. The diesel engine according to claim 1, wherein
The diesel smoke purification means includes a particulate filter that collects exhaust particulate discharged from the engine, and an oxidation catalyst disposed upstream of the particulate filter in the exhaust passage. A featured diesel engine. The diesel engine according to claim 1 or 2,
The diesel engine according to claim 1, wherein the regeneration processing unit includes a start reference value changing unit that changes the start reference value to be longer as the amount of fuel injected for engine operation increases. The diesel engine according to claim 1 or 2,
Exhaust temperature detection means for detecting the exhaust temperature of the engine is further provided,
The diesel engine according to claim 1, wherein the regeneration processing unit includes a start reference value changing unit that changes the start reference value longer as the exhaust temperature detected by the exhaust temperature detecting unit is lower. The diesel engine according to claim 4,
The diesel engine characterized in that the starting reference value changing unit changes the starting reference value to be longer as the amount of fuel injected for engine operation increases.

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