JP2008133740A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device of an internal combustion engine capable of stably changing an engine torque to the required value irrespective of an opened/closed state of an exhaust throttle valve by suppressing that the transition of the engine torque becomes different depending on the opening/closing state of the exhaust throttle valve. <P>SOLUTION: At the time of a transient operation in acceleration and deceleration of a vehicle, a fuel injection amount is once changed to a transient target value in starting of the transient operation, and after that, the fuel injection amount is gradually changed from the transient target value to the final target value. When the exhaust throttle valve 18 is in a valve closed state, the transient target value is set to be a larger value compared to the time when the exhaust throttle valve 18 is in a valve-opened state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine mounted on a vehicle provided with a filter that collects particulate matter in exhaust gas and an exhaust throttle valve that changes a flow passage cross-sectional area of the exhaust passage downstream thereof. The present invention relates to a fuel injection control device for an internal combustion engine that gradually changes the injection amount when the combustion injection amount is changed as the vehicle shifts to a transient operation state.

Conventionally, as an exhaust gas purification device applied to an internal combustion engine such as a vehicle-mounted diesel engine, a filter for collecting particulate matter (PM) discharged from the internal combustion engine is disposed in the exhaust passage, and the PM emission amount There is known one that reduces the above. In order to remove the PM accumulated on the filter, as described in Patent Document 1, for example, an exhaust throttle valve is provided on the downstream side of the filter, and the exhaust throttle valve is closed to reduce the pressure in the exhaust passage. It is known that the combustion of PM accumulated on the filter is promoted by raising the value of.
JP 2001-27145 A

  By the way, in the internal combustion engine, the fuel injection amount is set between its current value and the final target value in order to suppress a torque shock caused by a rapid change in the fuel injection amount when the vehicle is accelerated or decelerated. A gradual change control of the fuel injection amount is executed, such as once changing to the transient target value and then gradually changing from the transient target value to the final target value. In this way, when the fuel injection amount gradual change control is executed, if the exhaust throttle valve is opened or closed differently, the engine torque loss due to the exhaust throttle being throttled by the exhaust throttle valve is different. It will be a thing. As a result, the transition of the engine torque during acceleration / deceleration varies depending on the open / close state of the exhaust throttle valve at that time, for example, acceleration performance during acceleration decreases, or excessive torque shock occurs during deceleration. Such problems may occur.

  The present invention has been made in view of the above circumstances, and its object is to suppress the change in engine torque depending on the open / close state of the exhaust throttle valve and to control the engine torque according to the open / close state of the exhaust throttle valve. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can be stably changed to the required value.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a filter for collecting particulate matter in the exhaust gas is provided in the exhaust passage, and the flow passage cross-sectional area of the exhaust passage is provided downstream of the filter. In an internal combustion engine mounted on a vehicle provided with an exhaust throttle valve for changing the fuel injection amount, at the time of transient operation at the time of acceleration and deceleration of the vehicle, the fuel injection amount is temporarily set to a transient target value at the start of the transient operation. In the fuel injection control device for an internal combustion engine that gradually changes the fuel injection amount from the transient target value to the final target value, the transient target value is the same as the exhaust throttle when the exhaust throttle valve is closed. The gist is that the valve is set to a larger value than when the valve is open.

  According to this configuration, the transient target value for the fuel injection amount can be set in a manner reflecting the loss of engine torque that occurs when the exhaust throttle valve is closed, and the engine during the transient operation of the vehicle can be set. The engine torque can be stably changed to the required value regardless of the open / closed state of the exhaust throttle valve by suppressing the change in torque depending on the open / closed state of the exhaust throttle valve.

  In order to solve the above problem, the invention according to claim 2 is characterized in that a filter for collecting particulate matter in the exhaust gas is provided in the exhaust passage, and the flow passage cross-sectional area of the exhaust passage is provided downstream of the filter. In an internal combustion engine mounted on a vehicle provided with an exhaust throttle valve for changing the fuel injection amount, at the time of acceleration operation of the vehicle, the fuel injection amount is temporarily changed to a transient target value at the start of acceleration operation, and then fuel injection In the fuel injection control device for an internal combustion engine that gradually increases the amount from the transient target value to the final target value, the gradual change speed when the fuel injection amount is gradually increased from the transient target value to the final target value is The gist is that when the exhaust throttle valve is in the closed state, the exhaust throttle valve is set to a larger value than when the exhaust throttle valve is in the open state.

  According to this configuration, the gradual change speed of the fuel injection amount during acceleration operation can be set in a manner that reflects the loss of engine torque that occurs when the exhaust throttle valve is in the closed state. The engine torque can be changed to the required value stably regardless of the open / close state of the exhaust throttle valve by suppressing the change of the engine torque at different times depending on the open / close state of the exhaust throttle valve. Become.

  In order to solve the above-mentioned problem, the invention according to claim 3 is provided with a filter for collecting particulate matter in the exhaust gas in the exhaust passage, and a flow passage cross-sectional area of the exhaust passage on the downstream side of the filter. In an internal combustion engine mounted on a vehicle provided with an exhaust throttle valve for changing the fuel injection amount, at the time of deceleration operation of the vehicle, the fuel injection amount is temporarily changed to a transient target value at the start of deceleration operation, and then fuel injection In the fuel injection control device for an internal combustion engine that gradually decreases the amount from the transient target value to the final target value, the gradual change speed when the fuel injection amount is gradually decreased from the transient target value to the final target value is The gist is that when the exhaust throttle valve is in the closed state, the exhaust throttle valve is set to a smaller value than when the exhaust throttle valve is in the open state.

  According to this configuration, it is possible to set the gradual change speed of the fuel injection amount during deceleration operation in a manner that reflects the loss of engine torque that occurs when the exhaust throttle valve is in the closed state. The engine torque can be changed to the required value stably regardless of the open / close state of the exhaust throttle valve by suppressing the change of the engine torque at different times depending on the open / close state of the exhaust throttle valve. Become.

  Here, as in the invention described in claim 4, the transient target value is the same in an unloaded state of the internal combustion engine, in other words, in a state where the output shaft of the internal combustion engine and the input shaft of the vehicle drive system are disconnected. It is desirable to set this as the no-load reference injection amount at which the internal combustion engine can operate independently. According to such a configuration, it is possible to suppress the occurrence of a torque shock when the fuel injection amount is changed to the transient target value as the transient operation is started.

  In addition, since the internal combustion engine has higher friction at the movable part as the engine speed is higher, the fuel injection amount for enabling the self-sustained operation is increased. Therefore, as described in claim 5, at least the engine speed is included as a parameter for setting the no-load reference injection amount, and the no-load reference injection amount is set to a larger value as the engine rotation speed is higher. It is desirable to do.

  According to a sixth aspect of the present invention, in the fuel injection control device for an internal combustion engine according to any one of the first to fifth aspects, the exhaust pressure of the exhaust passage is detected upstream of the exhaust throttle valve. The gist is to further include a pressure sensor, and to determine that the exhaust throttle valve is in a closed state when the exhaust pressure detected by the pressure sensor is equal to or higher than a predetermined value.

  The opening degree of the exhaust throttle valve directly detects the open / closed state of the exhaust throttle valve, and the pressure of the exhaust passage that changes as the exhaust throttle valve opens and closes as in the invention of claim 6. It may be detected by a sensor and this may be determined according to the detected value.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a fuel injection control device for a diesel engine will be described with reference to FIGS.

  FIG. 1 is a schematic diagram showing a configuration of a diesel engine (hereinafter simply referred to as an engine) 10 equipped with a fuel injection control device according to the present invention. The intake passage 13 of the engine 10 is provided with an intake throttle valve 15 whose passage area is variable. The intake throttle valve 15 is driven by an actuator 17 and its opening degree is controlled, whereby the combustion chamber 12 is controlled. The intake air sucked in is metered. The air sucked into the intake passage 13 is mixed with the fuel injected from the fuel injection valve 16 provided in the combustion chamber 12 to become an air-fuel mixture, burned in the combustion chamber 12, and then discharged to the exhaust passage 14. An air flow meter 31 for detecting the intake air amount is provided upstream of the intake throttle valve 15 in the intake passage 13.

  The exhaust passage 14 includes a CCO (oxidation catalytic converter) 23 that oxidizes and purifies harmful HC and CO contained in the exhaust, and a DPF (diesel particulate filter) 24 that collects PM (particulate matter). Arranged in order, exhaust generated by combustion in the combustion chamber 12 is sent. The DPF 24 is formed of a porous material, and PM in the exhaust gas is collected in the pores. Then, the PM collected by the DPF 24 is burned (oxidized) and removed by the heat generated by the oxidation reaction of the CCO 23.

  Further, an exhaust temperature sensor 32 for detecting the temperature of the exhaust gas flowing into the CCO 23 and the DPF 24 is provided upstream of the CCO 23 in the exhaust passage 14, and a pressure sensor 33 is provided between the CCO 23 and the DPF 24. . The pressure sensor 33 detects a gauge pressure as a detection value, that is, a pressure using the atmospheric pressure as a reference pressure.

  An exhaust throttle valve 18 is provided on the downstream side of the DPF 24 in the exhaust passage 14. The exhaust throttle valve 18 is selectively driven between an open state and a closed state by an actuator 19, and the drive of the actuator 19 is switched by a vacuum switching valve (not shown).

  Further, the exhaust passage 14 is provided with a bypass passage 20 that connects the upstream side and the downstream side of the exhaust throttle valve 18 and bypasses the exhaust throttle valve 18. The bypass passage 20 is provided with a waste gate valve 21 that adjusts the pressure on the upstream side of the exhaust throttle valve 18. The waste gate valve 21 is a self-regulating valve, and opens when the pressure difference between the upstream side and the downstream side of the exhaust throttle valve 18 exceeds a predetermined pressure value, and adjusts the upstream pressure.

  Various controls of the engine 10 are executed by the electronic control unit 40. The electronic control unit 40 includes a CPU that executes various arithmetic processes related to engine control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores arithmetic results of the CPU, and the like. It is composed of input / output ports for inputting / outputting signals.

  In addition to the exhaust temperature sensor 32 and the pressure sensor 33 described above, an engine rotation speed sensor 35 that detects the engine rotation speed, an accelerator pedal operation amount, that is, an accelerator opening is detected at the input port of the electronic control unit 40. 36, an intake throttle sensor 37 for detecting the opening of the intake throttle valve 15 is connected. Further, the drive circuits of the intake throttle valve 15, the fuel injection valve 16, and the exhaust throttle valve 18 are connected to the output port of the electronic control unit 40.

  The electronic control unit 40 outputs a command signal to the drive circuit of each device connected to the output port according to the engine operating state grasped from the detection signal input from each sensor. As a result, various controls such as opening control of the intake throttle valve 15, fuel injection control from the fuel injection valve 16, opening / closing control of the exhaust throttle valve 18, and abnormality determination between the exhaust throttle valve 18 and the waste gate valve 21 are electronically controlled. It is executed by the device 40.

  Here, although most of the PM collected by the DPF 24 is removed by the oxidation heat of the CCO 23, when a large amount of PM exceeding the removal capacity is generated, the amount of PM deposited on the DPF 24 increases. When the amount of accumulated PM is excessively large, the ventilation resistance in the DPF 24 is increased, and the engine output is reduced or the collecting ability thereof is lowered. For this reason, in order to remove the PM accumulated in this way, in the engine 10 of this embodiment, the filter regeneration control for purifying the DPF 24 by burning the PM accumulated in the DPF 24 is executed by the electronic control unit 40. In this filter regeneration control, the PM collected in the DPF 24 is combusted by closing the exhaust throttle valve 18 and raising the exhaust temperature and the exhaust pressure under the condition that the PM accumulation amount is determined to exceed a predetermined amount. I try to let them.

  In addition to the filter regeneration control, the electronic control unit 40 controls the fuel injection amount based on the engine operating state. Specifically, the target value of the fuel injection amount is basically set based on the accelerator opening detected by the accelerator sensor 36 and the engine speed detected by the engine speed sensor 35. However, if the fuel injection amount is suddenly changed so as to coincide with the set target value, a sudden change in engine torque, so-called torque shock, may occur. Therefore, in order to suppress the occurrence of such a torque shock, the fuel injection amount is set between a current target value and a final target value (hereinafter referred to as a final target value) set based on the engine operating state. The fuel injection amount is gradually changed to the target value (hereinafter referred to as the transient target value) and then gradually changed from the transient target value to the final target value. Hereinafter, the gradual change control of the fuel injection amount will be described in more detail with reference to FIG. FIG. 2 shows a change in the fuel injection amount with respect to a change in the accelerator opening.

  As shown in FIG. 2, for example, the accelerator pedal is suddenly opened at timing T1 when the accelerator pedal is not operated and the fuel injection amount gradually decreases (for example, the accelerator opening increases within a predetermined time). When the amount is increased to a predetermined value or more), the final target value QLa of the fuel injection amount is set as described above. Thereafter, the fuel injection amount is changed so that the fuel injection amount coincides with the final target value QLa, but at the timing T1, the fuel injection amount is temporarily changed to the transient target value QTa. Here, the transient target value QTa is set so that a magnitude relationship of Q <QTa <QLa is established between the final target value QLa and the fuel injection amount Q at the timing T1. Thereafter, the fuel injection amount is gradually increased until reaching the final target value QLa (timing T1 to T2).

  On the other hand, when the operation of the accelerator pedal is released at the timing T3 and the closing operation is suddenly performed (for example, an operation in which the accelerator opening decrease amount within a predetermined time becomes equal to or greater than a predetermined value), the final target value QLb of the fuel injection amount is set. At the same time, the fuel injection amount is changed to the transient target value QTb. Here, the transient target value QTb is set so that a magnitude relationship of Q <QTb <QLb is established between the final target value QLb and the fuel injection amount Q at the timing T3, as in acceleration. Thereafter, the fuel injection amount is gradually reduced until reaching the final target value QLb (timing T3 to T4).

Next, the procedure for setting the above-described transient target values QTa and QTb will be described in more detail with reference to FIG.
In the present embodiment, the transient target values QTa and QTb at the time of acceleration / deceleration are determined when the engine 10 is independent in a no-load state of the engine 10, in other words, in a state where the output shaft of the engine 10 and the input shaft of the vehicle drive system are disconnected. It is set as a no-load reference injection amount that can be operated. Specifically, as shown in FIG. 3, the transient target values QTa and QTb are based on the engine speed at the time when the engine 10 shifts to the acceleration state or the deceleration state (timing T1 and T3 shown in FIG. 2). The transient target values QTa and QTb increase as the engine speed increases.

  Here, when the above-described filter regeneration control of the DPF 24 is executed, the exhaust throttle valve 18 is closed, so that the engine torque is reduced as compared with the case where the exhaust throttle valve 18 is closed. Loss increases. Therefore, the transition of the engine torque during acceleration / deceleration varies depending on the open / close state of the exhaust throttle valve 18 at that time, for example, acceleration performance during acceleration decreases, or excessive torque shock occurs during deceleration. Problems may occur.

  Therefore, in the present embodiment, the transient target values QTa and QTb are set in consideration of the open / closed state of the exhaust throttle valve 18. That is, as shown by the solid line and the alternate long and short dash line in FIG. 3, the transient target values QTa and QTb are larger when the exhaust throttle valve 18 is in the closed state than when it is in the opened state. Is set.

  The open / close state of the exhaust throttle valve 18 is grasped by the detection value of the pressure sensor 33 provided on the upstream side. That is, when the exhaust throttle valve 18 is in the closed state, the ventilation resistance in the exhaust passage 14 increases and the detected value of the pressure detected by the pressure sensor 33 also increases, so that the exhaust pressure detected by the pressure sensor 33 increases. When it is equal to or greater than the predetermined value, it can be determined that the exhaust throttle valve 18 is closed. Therefore, there is a case where there is a time lag after the drive signal is output to the drive circuit of the exhaust throttle valve 18 until the exhaust throttle valve 18 is actually closed and the exhaust pressure changes to a value corresponding thereto. However, such a time lag can be reflected in the control.

According to the fuel injection control device of the present embodiment described above, the following effects can be obtained.
(1) The transient target values QTa and QTb at the time of acceleration / deceleration are set to larger values when the exhaust throttle valve 18 is in the closed state than when the exhaust throttle valve 18 is in the opened state. Therefore, the transient target values QTa and QTb related to the fuel injection amount can be set in a manner reflecting the loss of the engine torque generated when the exhaust throttle valve 18 is in the closed state, and the engine during the transient operation of the vehicle can be set. The engine torque can be stably changed to the required value regardless of the open / closed state of the exhaust throttle valve 18 by suppressing the change in torque depending on the open / closed state of the exhaust throttle valve 18. .

  (2) Further, the transient target values QTa and QTb are set as no-load reference injection amounts at which the engine 10 can operate independently in a no-load state. Therefore, it is possible to suppress the occurrence of torque shock when the fuel injection amount is changed to the transient target values QTa and QTb as the transient operation is started.

  (3) Since at least the engine speed is included as a parameter for setting the transient target values QTa and QTb, and the higher the engine speed, the larger the transient target values QTa and QTb are set. The transient target values QTa and QTb can be set reflecting the increase in friction at.

  (4) A pressure sensor 33 is provided upstream of the exhaust throttle valve 18 to detect the exhaust pressure of the exhaust passage 14, and the exhaust throttle valve 18 is detected when the exhaust pressure detected by the pressure sensor 33 is greater than or equal to a predetermined value. Was determined to be in a closed state. Therefore, even if there is a time lag from when the drive signal is output to the drive circuit of the exhaust throttle valve 18 until the exhaust throttle valve 18 is actually driven to the closed state and the exhaust pressure changes, the pressure By determining that the exhaust throttle valve 18 is closed based on the detection value of the sensor 33, this time lag can be reflected in the control, and the transient target values QTa and QTb are actually opened and closed. It becomes possible to set the value according to.

(Second Embodiment)
Next explained is the second embodiment of the invention. In the present embodiment, not only the transient target values QTa and QTb are set based on the open / closed state of the exhaust throttle valve 18, but also the fuel injection amount is gradually increased from the transient target values QTa and QTb to the final target values QLa and QLb. The gradual change speed at the time of changing to is set according to the open / close state. Hereinafter, a procedure for setting the gradual change speed will be described with reference to FIG. FIG. 4 shows a change in the fuel injection amount with respect to a change in the accelerator opening.

  As shown in FIG. 4, for example, when the accelerator pedal is operated at the timing T1 when the accelerator pedal is not operated and the fuel injection amount gradually decreases, as described above, the final target of the fuel injection amount is set. The value QLa is set. Then, the fuel injection amount is changed to make the fuel injection amount coincide with the final target value QLa, but at the timing T1, the fuel injection amount is temporarily changed to the transient target value QTa according to the open / close state of the exhaust throttle valve 18. Thereafter, the fuel injection amount is gradually increased until the final target value QLa is reached. At this time, when the exhaust throttle valve 18 is in the closed state, as shown by the one-dot chain line in the figure, the gradual change rate of the fuel injection amount is compared with the case where the exhaust throttle valve 18 is in the open state. That is, the increase value per time is set large.

  On the other hand, when the operation of the accelerator pedal is released at timing T2, the final target value QLb of the fuel injection amount is set, and the fuel injection amount is temporarily changed to the transient target value QTb according to the open / close state of the exhaust throttle valve 18. Is done. The fuel injection amount is gradually decreased until the final target value QLb is reached. At this time, when the exhaust throttle valve 18 is in the closed state, as shown by the alternate long and short dash line in the figure, compared with the case where the exhaust throttle valve 18 is in the open state, the change rate of the fuel injection amount, That is, the reduction value per time is set to a small value.

  As described above, in this embodiment, in addition to the change of the transient target values QTa and QTb according to the open / close state of the exhaust throttle valve 18 of the first embodiment, the fuel injection amount is changed from the transient target value QTa to the final target value QLa. When the exhaust throttle valve 18 is in the closed state, the gradual change speed when the amount is gradually increased is set to a larger value than when the exhaust throttle valve 18 is in the open state. Further, when the exhaust throttle valve 18 is in the closed state, the gradual change speed when the fuel injection amount is gradually decreased from the transient target value QTb to the final target value QLb is set. I set it to a small value compared to the time. Therefore, the gradual change speed of the fuel injection amount during acceleration operation can be set in a manner reflecting the loss of engine torque generated when the exhaust throttle valve 18 is closed, and the engine during transient operation of the vehicle can be set. The engine torque can be stably changed to the required value regardless of the open / closed state of the exhaust throttle valve 18 by suppressing the change in torque depending on the open / closed state of the exhaust throttle valve 18. .

In addition, each said embodiment can also be implemented with the form changed suitably as follows.
In each of the above embodiments, the open / closed state of the exhaust throttle valve 18 is determined based on the detection value from the pressure sensor 33. However, a sensor for detecting the opening degree of the exhaust throttle valve 18 is provided. It is also possible to adopt a configuration in which the determination is made according to this value or a configuration in which the determination is made from the drive signal to the exhaust throttle valve 18.

  When the no-load reference injection amount is used as the values of the transient target values QTa and QTb, this value may be calculated by including not only the engine speed but also other parameters such as the vehicle speed.

  The values of the transient target values QTa and QTb are values that can change the engine torque with a certain degree of responsiveness to the operation of the accelerator pedal while suppressing the torque shock, even if it is not the no-load reference injection amount. Good.

  In the second embodiment, the gradual change speed is set in accordance with the open / close state of the exhaust throttle valve 18 both at the time of acceleration and at the time of deceleration. It is also possible to change the variable speed.

  In the second embodiment, both the change of the transient target values QTa and QTb and the change of the change rate are performed according to the open / close state of the exhaust throttle valve 18, but only the change of change rate is changed. May be.

The schematic diagram which shows the structure of diesel. The timing chart which shows the correlation with the change of an accelerator opening, and the change of fuel injection quantity. The graph which shows the change of the transient fuel injection amount set according to the opening / closing state of an exhaust throttle valve. The timing chart which shows the correlation with the change of the throttle opening in 2nd Embodiment, and the change of fuel injection quantity.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 14 ... Exhaust passage, 18 ... Exhaust throttle valve, 33 ... Pressure sensor, 40 ... Electronic control apparatus (fuel injection control apparatus).

Claims (6)

An internal combustion engine mounted on a vehicle in which an exhaust passage is provided with a filter that collects particulate matter in the exhaust, and an exhaust throttle valve that changes a flow passage cross-sectional area of the exhaust passage is provided downstream of the filter. Then, during at least one transient operation during acceleration and deceleration of the vehicle, the fuel injection amount is temporarily changed to the transient target value at the start of the transient operation, and then the fuel injection amount is changed from the transient target value to the final target. In a fuel injection control device for an internal combustion engine that gradually changes to a value,
The fuel injection control device for an internal combustion engine, wherein the transient target value is set larger when the exhaust throttle valve is in a closed state than when the exhaust throttle valve is in an open state. An internal combustion engine mounted on a vehicle in which an exhaust passage is provided with a filter that collects particulate matter in the exhaust, and an exhaust throttle valve that changes a flow passage cross-sectional area of the exhaust passage is provided downstream of the filter. Then, at the time of acceleration operation of the vehicle, the internal combustion engine that changes the fuel injection amount to the transient target value at the start of the acceleration operation and then gradually increases the fuel injection amount from the transient target value to the final target value In the fuel injection control device of
The gradual change speed when the fuel injection amount is gradually increased from the transient target value to the final target value is compared with that when the exhaust throttle valve is in a closed state when the exhaust throttle valve is in a closed state. The fuel injection control device for an internal combustion engine is characterized by being set to a large value. An internal combustion engine mounted on a vehicle in which an exhaust passage is provided with a filter that collects particulate matter in the exhaust, and an exhaust throttle valve that changes a flow passage cross-sectional area of the exhaust passage is provided downstream of the filter. An internal combustion engine that changes the fuel injection amount to the transient target value at the start of the deceleration operation and then gradually decreases the fuel injection amount from the transient target value to the final target value during deceleration operation of the vehicle. In the fuel injection control device of
When the exhaust throttle valve is in the closed state, the gradual change speed when the fuel injection amount is gradually decreased from the transient target value to the final target value is compared with that when the exhaust throttle valve is in the open state. The fuel injection control device for an internal combustion engine is characterized by being set to a small value. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 3,
The fuel injection control device for an internal combustion engine, wherein the transient target value is set as a no-load reference injection amount at which the internal combustion engine can operate independently in a no-load state. The fuel injection control device for an internal combustion engine according to claim 4,
The fuel injection control for an internal combustion engine characterized in that it includes at least an engine speed as a parameter for setting the no-load reference injection amount, and the unload reference injection amount is set to a larger value as the engine speed is higher. apparatus. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 5,
A pressure sensor is provided upstream of the exhaust throttle valve to detect the exhaust pressure of the exhaust passage, and the exhaust throttle valve is closed when the exhaust pressure detected by the pressure sensor is greater than or equal to a predetermined value. A fuel injection control device for an internal combustion engine, characterized in that:

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