JP6614065B2 - Fuel injection control device and program - Google Patents

Description

  The present disclosure relates to a fuel injection control device and a program for performing OT increase correction.

  For example, an exhaust system of an internal combustion engine mounted on a vehicle or the like is provided with a catalyst for purifying harmful substances contained in the exhaust gas. In this type of internal combustion engine, as a means for preventing performance deterioration and burning due to catalyst overheating, it is known to increase the fuel injection amount and to lower the exhaust gas temperature by the heat of vaporization of the fuel. Such means is called OT increase correction. OT is an abbreviation for Over Temperature (Protection).

  Conventionally, in the OT increase correction, the fuel injection amount to be increased is determined based on the temperature of the exhaust gas. The increase in the fuel injection amount determined in this way is referred to as a base correction amount. Thereby, the temperature rise of exhaust gas can be suppressed and catalyst overheating can be prevented. However, since the temperature of the catalyst rises with a delay with respect to the temperature of the exhaust gas, it takes time until the temperature of the catalyst reaches an overheated state even if the temperature of the exhaust gas increases. Originally, even if the exhaust gas temperature is high, the OT increase correction is not necessary if the catalyst temperature is low. However, when performing OT increase correction according to the base correction amount, unnecessary OT increase correction may be performed in a transient state where the temperature of the catalyst rises. When such unnecessary OT increase correction is performed, fuel consumption and emission are deteriorated.

  On the other hand, Patent Document 1 describes a technique for performing a decrease correction for reducing the increase in the fuel injection amount in accordance with the current temperature of the catalyst with respect to the base correction amount. Specifically, under the condition where the current temperature of the catalyst is equal to or higher than a predetermined value, a reduction correction amount corresponding to the current temperature of the catalyst is calculated, and the amount obtained by subtracting the reduction correction amount from the base correction amount is the actual fuel injection amount. Increase the amount. By doing in this way, it is supposed that it can suppress that the fuel injection quantity by OT increase correction becomes excessive.

JP 2011-220214 A

  In the prior art, the increase in the fuel injection amount in the OT increase correction is calculated based on the exhaust gas and the current temperature of the catalyst. However, even if the temperature is the same, the temporal change rate of the temperature of the catalyst differs depending on the flow rate of the exhaust gas at that time. In the prior art, the time change rate of the temperature of the catalyst is not taken into consideration. Therefore, even if the temperature of the catalyst rises rapidly or slowly, it is not reflected in the fuel injection amount in the OT increase correction.

  Under conditions where the temperature of the catalyst rises slowly, there is a time allowance until the temperature of the catalyst reaches an overheated state. Therefore, the increase in the fuel injection amount in the OT increase correction is essentially a rapid increase in the catalyst temperature. It should be less than the conditions you are doing. However, in the prior art, even under conditions where the temperature of the catalyst is rising slowly, the same OT increase correction is performed as in the conditions where the catalyst temperature is rising rapidly. The fuel injection amount is increased, which leads to deterioration of fuel consumption and emission.

  The present disclosure has been made to solve the above-described problems. The present disclosure provides a technique for realizing appropriate OT increase correction in a manner that considers the time change rate of the temperature of the catalyst.

  The fuel injection control device according to an aspect of the present disclosure includes a temperature acquisition unit (2, S100, S200), a temperature change rate calculation unit (2, S104, S204), and a reference temperature determination unit (2, S106, S206). And a control unit (2, S116, S226). Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with the specific means described in the embodiment described later as one aspect, and the technical scope of the present disclosure It is not limited.

  The temperature acquisition unit is configured to acquire the temperature of the catalyst provided in the exhaust system of the internal combustion engine. The temperature change rate calculation unit is configured to calculate a time change rate of the temperature acquired by the temperature acquisition unit. The reference temperature determination unit variably determines a reference temperature, which is a reference temperature for determining whether or not to perform the increase correction, according to the time change rate of the temperature calculated by the temperature change rate calculation unit. It is configured. The control unit is configured to perform the increase correction on the condition that the temperature of the catalyst exceeds the reference temperature determined by the reference temperature determination unit.

  According to the fuel injection control device according to the present disclosure, the OT increase correction is performed by variably determining the reference temperature for determining whether or not the OT increase correction is necessary according to the time change rate of the temperature of the catalyst. The timing to implement can be controlled. As a result, when the temperature of the catalyst is rapidly rising, the OT increase correction is applied quickly, while when the catalyst temperature is rising slowly, the useless OT increase correction is suppressed. Appropriate OT increase correction can be realized according to the time change rate of the temperature.

  Another form of the present disclosure may be made as a program executed by a computer. This program causes the computer to execute a temperature acquisition procedure (S100, S200), a temperature change rate calculation procedure (S104, S204), a reference temperature determination procedure (S106, S206), and a control procedure (S116, S226). It is configured as follows.

  In the temperature acquisition procedure, the computer acquires the temperature of the catalyst provided in the exhaust system of the internal combustion engine. In the temperature change rate calculation procedure, the computer calculates the time change rate of the temperature acquired in the temperature acquisition procedure. In the reference temperature determination procedure, the computer variably changes a reference temperature, which is a reference temperature for determining whether or not to perform the increase correction, according to the time change rate of the temperature calculated in the temperature change rate calculation procedure. decide. In the control procedure, the computer performs the increase correction on the condition that the temperature of the catalyst exceeds the reference temperature determined in the reference temperature determination procedure.

  As described above, if one aspect of the present disclosure is implemented as a program, the computer can be caused to function as the above-described fuel injection control device by executing each procedure.

The block diagram showing the schematic structure of an engine control system. The flowchart showing the procedure of the OT increase correction process of 1st Embodiment. The flowchart showing the procedure of the OT increase correction process of 2nd Embodiment. The figure explaining the problem in a prior art. The figure explaining the effect in this indication. The figure explaining the effect in this indication.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, this indication is not limited to the following embodiment, It is possible to implement in various aspects.
[Description of engine control system configuration]
The configuration of the engine control system 1 of the embodiment will be described with reference to FIG. As illustrated in FIG. 1, the engine control system 1 includes an ECU 2 that corresponds to an example of a fuel injection control device of the present disclosure, and an engine 3 that is a control target of the ECU 2.

  The engine 3 is an internal combustion engine in which the reciprocating motion of the piston 31 accommodated in the cylinder 30 is transmitted as a rotational motion to the crankshaft 4 via the connecting rod 33. The engine 3 includes a crank angle sensor 5, a fuel injection valve 6, an ignition device 7, an intake sensor 8, an exhaust sensor 9, a catalyst 10, an intake pipe 11, an exhaust pipe 12, an EGR pipe 13, and an EGR valve 14.

  The crank angle sensor 5 is, for example, a sensor that is provided in the cylinder 30 and outputs a rotation angle signal corresponding to the rotation of the crankshaft 4. The fuel injection valve 6 is a device that injects fuel into a combustion chamber 32 provided in the upper part of the cylinder 30 in accordance with control from the ECU 2. The ignition device 7 is a device that ignites a mixture of air and fuel compressed in the piston 31 in the combustion chamber 32.

  The intake pipe 11 is a duct for sucking outside air into the combustion chamber 32. An intake sensor 8 is provided in the intake pipe 11. The intake sensor 8 is a sensor that detects the temperature, flow rate, and pressure of air flowing through the intake pipe 11 and outputs a signal corresponding to the detected value. The exhaust pipe 12 is a pipe line for discharging exhaust gas from the combustion chamber 32. The exhaust pipe 12 is provided with an exhaust sensor 9 and a catalyst 10. The exhaust sensor 9 is a sensor that detects the temperature, flow rate, and pressure of the exhaust gas flowing through the exhaust pipe 12 and outputs a signal corresponding to the detected value. The catalyst 10 is a device that purifies harmful components contained in the exhaust gas discharged from the combustion chamber 32.

  The intake pipe 11 and the exhaust pipe 12 are connected by an EGR pipe 13 so that exhaust gas can flow. EGR is an abbreviation for Exhaust Gas Recirculation. The EGR pipe 13 is a pipe line for recirculating exhaust gas from the exhaust pipe 12 to the intake pipe 11. The EGR pipe 13 is provided with an EGR valve 14 that can open and close an exhaust gas passage. The EGR valve 14 is configured to be openable and closable at an arbitrary degree according to control by the ECU 2.

  By adjusting the degree to which the EGR valve 14 opens, the amount of exhaust gas recirculated from the exhaust pipe 12 to the intake pipe 11 through the EGR pipe 13 (hereinafter also referred to as EGR quantity) is controlled. Exhaust gas is recirculated to the intake pipe 11 through the EGR pipe 13 and re-intaked into the combustion chamber 32, so that the combustion temperature is lowered. Thereby, the nitrogen oxide in exhaust gas can be reduced or a fuel consumption can be improved.

  The ECU 2 is an information processing apparatus that is configured mainly with a CPU, RAM, ROM, semiconductor memory such as a flash memory (not shown), an input / output interface, and the like. The ECU 2 is embodied by, for example, a microcontroller or the like in which functions as a computer system are integrated. The function of the ECU 2 is realized by the CPU executing a program stored in a non-transitional tangible storage medium such as a ROM or a semiconductor memory. Note that the number of microcontrollers constituting the ECU 2 may be one or more. Further, the method of realizing the function of the ECU 2 is not limited to software, and some or all of the elements may be realized using hardware that combines a logic circuit, an analog circuit, and the like.

  The ECU 2 has a function of acquiring signals output from the crank angle sensor 5, the intake sensor 8, the exhaust sensor 9, and the like and detecting the operating state of the engine 3 based on these signals. The ECU 2 has a function of performing various engine controls such as fuel injection by the fuel injection valve 6, ignition by the ignition device 7, and adjustment of the EGR amount by opening and closing the EGR valve 14 in accordance with the detected operating state. Have.

  Further, the ECU 2 has a function of controlling the OT increase correction for increasing the fuel injection amount by the fuel injection valve 6 and lowering the temperature of the exhaust gas as a means for preventing the performance deterioration and burning due to the catalyst 10 being overheated.

[Description of OT Increase Correction Process of First Embodiment]
A first embodiment of the OT increase correction process executed by the ECU 2 will be described with reference to the flowchart of FIG. This OT increase correction process is performed separately from the process related to fuel injection control executed by the ECU 2. Further, this OT increase correction process is repeatedly performed at a cycle (for example, 100 msec) longer than the control cycle of the fuel injection control. This is because the catalyst temperature change speed is very small with respect to the control cycle of the fuel injection control, and the catalyst temperature change is effective even if the control cycle of the OT increase correction processing is shortened as in the fuel injection control. This is because it cannot be detected. Therefore, in consideration of reducing the processing load on the ECU 2, it is desirable to set the control cycle in accordance with the speed of temperature change of the catalyst.

  In S100, the ECU 2 calculates the convergence temperature T0 of the catalyst 10 and the current temperature T of the catalyst 10. The convergence temperature is a temperature at which the catalyst 10 converges when the engine 3 is operated in a certain operation state, and is approximated by the current temperature of the exhaust gas, for example. The convergence temperature T0 is calculated by, for example, a predetermined calculation from the intake air amount calculated from the air flow rate and pressure detected by the intake sensor 8 and the rotation speed of the engine 3 based on the rotation angle detected by the crank angle sensor 5. Can be guessed. Alternatively, the convergence temperature T0 may be estimated based on the temperature of the exhaust gas detected by the exhaust sensor 9.

  The temperature of the catalyst 10 varies depending on the heating by the exhaust gas and the reaction heat of the catalyst, but generally exhibits a first-order lag temperature change with respect to the exhaust gas temperature, and the rate of temperature change is determined according to the flow rate of the exhaust gas. It has been known. Therefore, the current temperature T is estimated by a predetermined calculation based on the convergence temperature T0.

  In S102, the ECU 2 calculates a basic correction amount Cbase based on the convergence temperature T0 calculated in S100. The basic correction amount Cbase is a basic value of the fuel injection amount increase (that is, the correction amount) in the OT increase correction. The basic correction amount Cbase is calculated by the following equation (1).

Cbase = map (T0) (1)
In the above equation (1), map (T0) is a convergence temperature calculated in S100 from a given map in which a set of convergence temperatures and a basic correction amount to be applied at each convergence temperature are recorded in association with each other. This is a value obtained by extracting the basic correction amount corresponding to T0. The basic correction amount map is set as a correction amount necessary for lowering the convergence temperature below the burnout temperature, which is a temperature at which the catalyst 10 may burn out, by the OT increase correction with respect to the current convergence temperature. To do.

  In S104, the ECU 2 calculates a temperature change rate ΔT based on the current temperature T calculated in S100. The temperature change rate ΔT is a value representing the time change rate of the temperature of the catalyst 10. The temperature change rate ΔT is calculated by the following equation (2).

ΔT = (T (n) -T (n-1)) / Int (2)
In the above equation (2), T (n) is a value of the current temperature T calculated in S100 in the current processing cycle in the OT increase correction processing that is periodically executed. T (n-1) is the value of the current temperature T calculated in S100 in the previous processing cycle. Int is a value representing the time interval of the processing cycle. In the present embodiment, it is assumed that the temperature change rate ΔT is calculated based on the amount of change from the temperature of the catalyst in the previous processing cycle. However, the temperature change rate ΔT may be calculated based on the amount of change from the temperature of the catalyst and a time difference before a predetermined time other than the previous processing cycle.

  In S106, the ECU 2 calculates a correction start temperature T1 based on the temperature change rate ΔT calculated in S104. The correction start temperature T1 is a temperature serving as a threshold for starting the OT increase correction, and is variably set according to the temperature change rate ΔT. The correction start temperature T1 is calculated by the following equation (3).

T1 = T10 + map (ΔT) (3)
In the above equation (3), T10 is a basic value of the correction start temperature, and is a value set as the minimum value of the correction start temperature. map (ΔT) is a temperature change rate ΔT calculated in S104 from a given map in which a set of temperature change rates and correction values of correction start temperatures to be applied at the respective temperature change rates are recorded in association with each other. Is a value obtained by extracting a correction value corresponding to. The map of correction values related to the correction start temperature is set so that the smaller the temperature change rate, the smaller the value (for example, the minimum value is 0), and the larger the temperature change rate, the larger the value.

  In S108, the ECU 2 compares the current temperature T with the correction start temperature T1, and determines whether or not the current temperature T is higher than the correction start temperature T1. When the current temperature T is higher than the correction start temperature T1 (that is, S108: YES), the ECU 2 proceeds to S110.

  In S110, the ECU 2 calculates a decrease correction amount Ccmp based on the temperature difference between the current temperature T and the correction start temperature T1. The decrease correction amount Ccmp is a value representing the amount by which the correction amount for OT increase correction is reduced from the basic correction amount Cbase. The reduction correction amount Ccmp is calculated by the following equation (4).

Ccmp = map (T1-T) (4)
In the above equation (4), map (T1-T) is a given record in which a set of differences between the current temperature and the correction start temperature is recorded in association with a reduction correction amount to be applied to each difference. This is a value obtained by extracting a reduction correction amount corresponding to the difference between the current temperature T and the correction start temperature T1 from the map. The map for the amount of reduction correction is set so that the smaller the absolute value of the difference between the correction start temperature and the current temperature, the lower the value, and the smaller the absolute value of the difference between the correction start temperature and the current temperature, the higher the value. Yes. By doing so, the correction amount for the OT increase correction is reduced when the temperature of the catalyst 10 is low, and the correction amount is increased to the basic correction amount as the temperature of the catalyst 10 rises. That is, the reduction correction is finally set to zero.

  On the other hand, when it is determined in S108 that the current temperature T is equal to or lower than the correction start temperature T1 (that is, S108: NO), the ECU 2 proceeds to S112. In S112, the ECU 2 cancels the OT increase correction. Specifically, the ECU 2 sets the reduction correction amount Ccmp to the same value as the basic correction amount Cbase. In this manner, the correction amount is corrected to 0 in the next S114, and the OT increase correction is substantially not performed.

  In S114, the ECU 2 calculates the net correction amount Cfix based on the decrease correction amount Ccmp set in S110 or S112. The net correction amount Cfix is a value representing the actual correction amount applied when the OT increase correction is executed. The net correction amount Cfix is calculated by the following equation (5).

Cfix = Cbase-Ccmp (5)
In the above equation (5), when the decrease correction amount Ccmp is set to the same value as the basic correction amount Cbase, the net correction amount Cfix becomes 0, and the OT increase correction is cancelled.

  In S116, the ECU 2 executes the OT increase correction according to the net correction amount Cfix calculated in S114. Specifically, the ECU 2 increases the amount of fuel corresponding to the net correction amount Cfix with respect to the optimal fuel injection amount set according to the operating state, and injects the fuel from the fuel injection valve 6.

[Description of Increase Correction Control of Second Embodiment]
A second embodiment of the OT increase correction process executed by the ECU 2 will be described with reference to the flowchart of FIG. The OT increase correction process of the second embodiment is different from the first embodiment in that the net correction amount of the OT increase correction is calculated in consideration of the decrease in the exhaust temperature due to the increase in EGR.

  EGR has the effect of lowering the exhaust temperature, and is expected to have the same effect as the OT increase correction. Therefore, the net correction amount can be reduced by adding the decrease in exhaust temperature due to the increase in EGR to the decrease correction amount in the OT increase correction. However, EGR is not always available depending on the operating condition of the engine 3, and is less responsive to the exhaust gas temperature drop than the OT increase correction, so it is used as an auxiliary depending on the situation. And Hereinafter, processing parts different from those of the first embodiment will be mainly described, and a part of the processing parts common to the first embodiment will be omitted.

  Each procedure of S200, S202, S204, S206, 208 is the same as each procedure of S100, S102, S104, S106, S208 of the first embodiment. When it is determined in S208 that the current temperature T is higher than the correction start temperature T1 (that is, S208: YES), the ECU 2 proceeds to S210.

  In S210, the ECU 2 determines whether or not the temperature change rate ΔT calculated in S204 is equal to or less than a predetermined threshold value. This threshold is a value that defines a condition under which EGR increase can be performed as an aid to OT increase correction. In the present embodiment, it is assumed that the increase in EGR is used as an auxiliary to the OT increase correction only under conditions where the temperature change rate of the catalyst 10 is relatively small, that is, there is a time allowance until the catalyst 10 overheats. doing.

  When the temperature change rate ΔT is equal to or less than the predetermined threshold (that is, S210: YES), the ECU 2 proceeds to S212. In S212, the ECU 2 determines whether or not the EGR can be further increased as an assist for the OT increase correction. Specifically, the ECU 2 determines whether or not there is room for an increase in the allowable range of the EGR amount applicable in the current operating state of the engine 3. If the EGR amount can be increased (that is, S212: YES), the ECU 2 proceeds to S214.

  In S <b> 214, the ECU 2 requests an increase in EGR to the process for adjusting the EGR amount by the EGR valve 14. In S216, the ECU 2 calculates a decrease amount Tegr of the exhaust gas temperature due to the increase in EGR requested in S214. The temperature decrease amount Tegr is calculated based on, for example, a given map in which the relationship between the EGR increase value and the exhaust gas temperature decrease amount is recorded.

In S218, the ECU 2 calculates a decrease correction amount Ccmp that takes into account the increase in EGR. The decrease correction amount Ccmp taking into account the increase in EGR is calculated by the following equation (6).
Ccmp = map ((T1 + Tegr) -T) (6)
The map used in the above equation (6) is the same as the map used in the above equation (4). In the above formula (6), the correction start temperature T1 is considered to be higher by the amount of temperature decrease Tegr due to the increase in EGR, so that the decrease correction amount Ccmp becomes larger than when the EGR increase is not performed. ing.

  On the other hand, if a negative determination is made in S210 or S212, the ECU 2 proceeds to S220. In S220, the ECU 2 calculates a decrease correction amount Ccmp that is not accompanied by an increase in EGR. The decrease correction amount Ccmp without increasing the EGR is calculated by the above equation (4) as in the first embodiment. On the other hand, if a negative determination is made in S208, the ECU 2 proceeds to S222. In S222, the ECU 2 cancels the OT increase correction. Specifically, the ECU 2 sets the reduction correction amount Ccmp to the same value as the basic correction amount Cbase.

  In S224, the ECU 2 calculates the net correction amount Cfix based on the reduction correction amount Ccmp set in S218, S220, or S222. It is calculated by the above equation (5) as in the first embodiment. In S226, the ECU 2 executes the OT increase correction according to the net correction amount Cfix calculated in S224. Specifically, the ECU 2 increases the amount of fuel corresponding to the net correction amount Cfix with respect to the optimal fuel injection amount set according to the operating state, and injects the fuel from the fuel injection valve 6.

[effect]
The effects of the engine control system 1 of the embodiment will be described with reference to the graphs of FIGS. In the graphs of FIGS. 4 to 6, the horizontal axis indicates time, and the vertical axis indicates the correction amount related to the temperature and OT increase correction. The exhaust system convergence temperature T0, the catalyst temperature T, the basic correction amount Cbase, and the net correction amount Cfix. Represents the time transition of.

  In the example of FIG. 4, it is assumed that the correction start temperature T1 is fixedly set as in the conventional technique. In the example of FIG. 4, the convergence temperature T0 has increased rapidly from the time t1. This sudden rise is caused by some abnormality that deviates from the normal operating state. As the convergence temperature T0 rapidly increases, the catalyst temperature T also increases rapidly with a delay. Then, the OT increase correction is started when the current temperature T reaches the correction start temperature T1 at time t2. Accordingly, the convergence temperature T0 is lowered, and the increase in the catalyst temperature T is suppressed.

  However, as illustrated in FIG. 4, in a situation where the catalyst temperature T rapidly increases, even if the OT increase correction is started when the catalyst temperature T reaches the correction start temperature T1, the temperature increase cannot be suppressed in time. The catalyst burnout temperature T2 may be exceeded. In particular, when the correction start temperature T1 is set to be relatively high from the viewpoint of emphasizing improvement in fuel consumption, there is a high possibility that such a situation will occur.

  In contrast to the case of FIG. 4, in the case of FIG. 5, it is assumed that the correction start temperature T1 is variably set by the engine control system 1 of the embodiment. In the example of FIG. 5, the correction start temperature T1 is set high before the time t1 when the convergence temperature T0 and the catalyst temperature T start to increase rapidly. Then, the correction start temperature T1 is lowered as the convergence temperature T0 and the catalyst temperature T rapidly increase from time t1. By reducing the correction start temperature T1, the OT increase correction is started at a time t2 ′ earlier than the time t2 in the example of FIG. Thereby, it is possible to prevent the catalyst temperature T from exceeding the catalyst burning temperature T2.

  On the other hand, in the case of FIG. 6, it is assumed that the correction start temperature T1 can be variably set by the engine control system 1 of the embodiment, similarly to the case of FIG. However, in the case of FIG. 6, it is assumed that the convergence temperature T0 and the catalyst temperature T rise more slowly than the cases of FIGS. In the example of FIG. 6, the correction start temperature T1 is maintained higher than the correction start temperature basic value T10 by gradually increasing the convergence temperature T0 and the catalyst temperature T.

  Thereby, the timing at which the OT increase correction is started is delayed as compared with the case where the correction start temperature T1 is set low. If the correction start temperature T1 is set to the correction start temperature basic value T10 in the example of FIG. 6, the OT increase correction is started at the time t3 ′. However, in practice, since the correction start temperature T1 is set higher than the correction start temperature basic value T10, the OT increase correction is started at a time t3 later than the time t3 ′. Therefore, the fuel consumption for the OT increase correction can be reduced by the delay of the timing at which the OT increase correction is started.

[Correspondence with configuration described in claims]
The correspondence between each configuration of the embodiment and the configuration described in the claims is as follows.
S100 and S200 executed by the ECU 2 correspond to processing as a temperature acquisition unit. S106 and S206 executed by the ECU 2 correspond to processing as a reference temperature determination unit. S116 and S226 executed by the ECU 2 correspond to processing as a control unit. S210 executed by the ECU 2 corresponds to processing as an EGR increase determination unit.

[Modification]
The functions of one component in each of the above embodiments may be shared by a plurality of components, or the functions of a plurality of components may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of the other above embodiments. It should be noted that all aspects included in the technical idea specified from the words described in the claims are embodiments of the present disclosure.

  The present disclosure is disclosed in various forms such as the above-described system including the ECU 2, a program for causing the computer to function as the ECU 2, a non-transition actual recording medium such as a semiconductor memory storing the program, and a fuel injection control method. It can also be realized.

  DESCRIPTION OF SYMBOLS 1 ... Engine control system, 2 ... ECU, 3 ... Engine, 4 ... Crankshaft, 5 ... Crank angle sensor, 6 ... Fuel injection valve, 7 ... Ignition device, 8 ... Intake sensor, 9 ... Exhaust sensor, 10 ... Catalyst, 11 ... Intake pipe, 12 ... Exhaust pipe, 13 ... EGR pipe, 14 ... EGR valve.

Claims (4)

A temperature acquisition unit (2, S100, S200) configured to acquire the temperature of the catalyst (10) provided in the exhaust system of the internal combustion engine;
A temperature change rate calculation unit (2, S104, S204) configured to calculate a time change rate of the temperature acquired by the temperature acquisition unit;
In order to prevent overheating of the catalyst, a reference temperature that is a reference temperature for determining whether or not to perform increase correction, which is correction for increasing the amount of fuel to be injected in the internal combustion engine, is used as the temperature change rate calculation unit. A reference temperature determination unit (2, S106, S206) configured to be variably determined according to the time change rate of the temperature calculated by
A controller (2, S116, S226) configured to perform the increase correction on the condition that the temperature of the catalyst exceeds the reference temperature determined by the reference temperature determination unit;
Equipped with a,
The exhaust system is provided with an exhaust gas recirculation device that recirculates a part of the exhaust gas after combustion to the intake passage of the internal combustion engine,
An EGR increase determination unit (2) configured to determine whether or not to increase the exhaust gas recirculation by the exhaust gas recirculation device according to the time change rate of the temperature calculated by the temperature change rate calculation unit. , S210),
The control unit makes a request to increase the exhaust gas recirculation to the exhaust gas recirculation device on the condition that the exhaust gas recirculation is determined to be increased by the EGR increase determination unit and the exhaust gas recirculation device. A fuel injection control device configured to perform control to decrease the increase correction in accordance with an increase in gas recirculation . The EGR increase determination unit is configured to determine a process for increasing the exhaust gas recirculation by the exhaust gas recirculation device on the condition that the time change rate of the temperature is a predetermined reference value or less. The fuel injection control device according to claim 1 . The reference temperature determination unit is configured to determine the reference temperature lower as the time change rate of the temperature is larger, and to determine the reference temperature higher as the time change rate of the temperature is smaller. A fuel injection control device according to claim 1 or 2 . A temperature acquisition procedure (S100, S200) for acquiring the temperature of the catalyst provided in the exhaust system of the internal combustion engine;
A temperature change rate calculation procedure (S104, S204) for calculating a time change rate of the temperature acquired in the temperature acquisition procedure;
In order to prevent overheating of the catalyst, a reference temperature, which is a reference temperature for determining whether or not to perform an increase correction, which is a correction for increasing the amount of fuel to be injected in the internal combustion engine, is used as the temperature change rate calculation procedure. A reference temperature determination procedure (S106, S206) that is variably determined according to the time change rate of the temperature calculated in
A control procedure (S116, S226) for performing the increase correction on the condition that the temperature of the catalyst exceeds the reference temperature determined in the reference temperature determination procedure;
To the computer ,
The exhaust system is provided with an exhaust gas recirculation device that recirculates a part of the exhaust gas after combustion to the intake passage of the internal combustion engine,
An EGR increase determination procedure (2, S210) for determining whether or not to increase the exhaust gas recirculation by the exhaust gas recirculation device according to the time change rate of the temperature calculated in the temperature change rate calculation procedure; Let the computer run,
In the control procedure, on the condition that the exhaust gas recirculation is determined to be increased in the EGR increase determination procedure, a request to increase the exhaust gas recirculation is made to the exhaust gas recirculation device, and A program for performing control to decrease the increase correction in accordance with an increase in exhaust gas recirculation .