JP2023166659A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

To provide a fuel injection control device for an internal combustion engine that can highly accurately suppress variation in injection quantity relative to an injection pulse width in a cold idle state.SOLUTION: A fuel injection control device for an internal combustion engine stores a pulse width of an injection pulse signal in a cold idle state, as a pseudo-pulse width, detects an operation state of a fuel injection device when injecting a required injection amount of fuel with the pseudo-pulse width in a post-warming-up idle state, provides a pulse width correction value on the basis of a detection result of the operation state, and corrects a pulse width of an injection pulse signal with the pulse width correction value in a cold idle state.SELECTED DRAWING: Figure 5

Description

The present invention relates to a fuel injection control device for an internal combustion engine.

The fuel injection control device for an internal combustion engine disclosed in Patent Document 1 changes the fuel injection pressure during idling operation to a plurality of different fuel injection pressure levels, and adjusts the actual injection amount with respect to the injection pulse time of the injector at the plurality of different fuel injection pressure levels. FCCB correction (rotational speed It is calculated for each cylinder by performing variable inter-cylinder injection amount correction) and ISC correction (average engine rotation speed correction).

Japanese Patent Application Publication No. 2008-101625

By the way, in a cold idle state (in other words, a fast idle state), split injection is performed in which fuel injection per cycle is divided into multiple times, and fuel spray is atomized by increasing the fuel pressure. In some cases, this can improve the exhaust properties.
However, when performing split injection or increasing the fuel pressure, the injection pulse width per injection becomes shorter, and the injection pulse width in the non-linear region where the variation in the injection amount (actual valve opening time) with respect to the injection pulse width increases. There were times when I had to use it.

When the engine is in a cold idle state and before air-fuel ratio feedback control starts, the influence of variation in injection amount becomes large, so the injection pulse width is adjusted by learning the variation in injection amount with respect to the injection pulse width in a cold idle state. It is desirable to suppress variations in injection amount by correcting.
However, in a cold idling state, the amount of fuel injected per combustion cycle is large, so there is a problem in that it is difficult to learn variations in the amount of injection with high accuracy due to the influence of fuel pressure pulsations.

The present invention has been made in view of the conventional situation, and its purpose is to provide a fuel injection control device for an internal combustion engine that can suppress variations in injection amount with respect to injection pulse width with high accuracy in a cold engine idle state. It is about providing.

Therefore, as one aspect of the fuel injection control device for an internal combustion engine according to the present invention, the pulse width of the injection pulse signal in the cold idle state is stored as a pseudo pulse width, and the pseudo pulse width is stored in the idle state after warm-up. detect the operating state of the fuel injection device when injecting the required injection amount with the width, determine the pulse width correction value based on the detection result of the operating state, and adjust the pulse width of the injection pulse signal to the pulse width of the injection pulse signal in the cold idle state. Correct using the pulse width correction value.

According to the above invention, in a cold idle state, variations in the injection amount with respect to the injection pulse width can be suppressed with high accuracy.

FIG. 1 is a configuration diagram of a fuel injection system for an internal combustion engine. FIG. 3 is a diagram showing the correlation between the injection pulse width and the injection amount, and the valve behavior of the fuel injector in a cold idle state and a warmed-up idle state. It is a time chart for explaining the detection method of valve closing time. FIG. 3 is a diagram showing the correlation between valve closing time and pulse width correction value. 7 is a flowchart showing a procedure for learning a pulse width correction value.

Embodiments of the present invention will be described below.
FIG. 1 is a configuration diagram showing one aspect of an internal combustion engine for a vehicle.
The internal combustion engine 101 includes a fuel injection valve 105 as a fuel injection device in each cylinder, and the fuel injection valve 105 injects fuel into the internal combustion engine 101.

A control device 109 having a function as a fuel injection control device controls the operation of the internal combustion engine 101 by controlling fuel injection by the fuel injection valve 105 and the like.
The control device 109 is an electronic control device including a microcomputer 109a, and the microcomputer 109a includes a microprocessor, rewritable nonvolatile memory, and the like.

Intake air from the internal combustion engine 101 passes through an air flow meter 120, an electronically controlled throttle valve 119, and a collector 115 in this order, and is then sucked into a combustion chamber 121 via an intake port 110 and an intake valve 103 provided in each cylinder.
Furthermore, the internal combustion engine 101 includes a variable fuel pressure device 129 that varies the pressure of fuel fed to the fuel injection valve 105.

The variable fuel pressure device 129 includes an electric low pressure fuel pump 124 and an engine driven high pressure fuel pump 125.
Low pressure fuel pump 124 sends fuel in fuel tank 123 to high pressure fuel pump 125 .

On the other hand, the high-pressure fuel pump 125 boosts the pressure of the fuel supplied from the low-pressure fuel pump 124 and sends the boosted high-pressure fuel to the fuel injection valve 105 via the high-pressure fuel pipe 128.
The control device 109 controls the pressure of fuel supplied to the fuel injection valve 105 to a target fuel pressure by adjusting the discharge amount of the high-pressure fuel pump 125.
The fuel pressure sensor 126 detects the fuel pressure FP within the high-pressure fuel pipe 128, that is, the fuel pressure FP supplied to the fuel injection valve 105.

Then, the control device 109 sets the operation amount of an electromagnetic metering valve (not shown) that adjusts the discharge amount of the high-pressure fuel pump 125 based on the deviation ΔFP between the fuel pressure FP detected by the fuel pressure sensor 126 and the target fuel pressure FPtg. This brings the fuel pressure FP detected by the fuel pressure sensor 126 closer to the target fuel pressure FPtg.
That is, the control device 109 has a function of outputting a control signal for an electromagnetic metering valve that adjusts the discharge amount of the high-pressure fuel pump 125 as a fuel pressure control signal, and controlling the fuel pressure FP supplied to the fuel injection valve 105.

The fuel injection valve 105 injects fuel directly into the combustion chamber 121 of the internal combustion engine 101 .
In other words, the internal combustion engine 101 is a direct injection type internal combustion engine.
The fuel injection valve 105 opens in response to the injection pulse signal output by the control device 109, and injects fuel into the combustion chamber 121 in an amount proportional to the pulse width of the injection pulse signal, that is, the valve opening control time. .

The control device 109 determines a required injection amount per combustion cycle according to engine operating conditions such as intake air flow rate, engine rotational speed, and cooling water temperature, and injects the required injection amount under the current fuel pressure. The injection pulse width that can be achieved is determined, and an injection pulse signal having such an injection pulse width is output to the fuel injection valve 105.
Further, the control device 109 divides the required injection amount into multiple times when the internal combustion engine 101 is in a cold idle state, that is, when the internal combustion engine 101 is in an idling operation before completion of warm-up, where the temperature of the internal combustion engine 101 is lower than the set temperature. Split injection (in other words, multi-stage injection) control is performed.

Further, the internal combustion engine 101 includes an ignition device having an ignition coil 107 and a spark plug 106.
The control device 109 controls the generation of sparks by the spark plug 106 by controlling the energization of the ignition coil 107 .

The air-fuel mixture in the combustion chamber 121 is ignited and combusted by the spark generated by the ignition plug 106, and exhaust gas produced by the combustion is discharged from the combustion chamber 121 to the exhaust pipe 111 via the exhaust valve 104.
The exhaust pipe 111 is equipped with a catalytic converter 112 containing a three-way catalyst for purifying exhaust gas.

The control device 109 acquires detection signals output from various sensors that detect the operating state of the internal combustion engine 101. In other words, the control device 109 acquires information regarding the operating state of the internal combustion engine 101 from various sensors.
The control system for the internal combustion engine 101 includes, as the various sensors described above, a water temperature sensor 108 that detects the cooling water temperature TW representing the temperature of the internal combustion engine 101, and a rotation angle of the crankshaft of the internal combustion engine 101, in addition to the fuel pressure sensor 126 described above. a crank angle sensor 116 that measures the intake air flow rate QA of the internal combustion engine 101; an air flow meter 120 that measures the intake air flow rate QA of the internal combustion engine 101; an air-fuel ratio sensor 113 that detects the air-fuel ratio based on the oxygen concentration of exhaust gas upstream of the catalytic converter 112; The accelerator opening sensor 122 is provided to detect the opening degree ACC of an accelerator pedal operated by a person.

Then, the control device 109 calculates the required torque of the internal combustion engine 101 based on the accelerator opening degree ACC detected by the accelerator opening degree sensor 122, and determines whether the internal combustion engine 101 is in an idling operating state.
Further, the control device 109 calculates the rotation speed NE of the internal combustion engine 101 based on the rotation angle of the crankshaft detected by the crank angle sensor 116.
Further, the control device 109 determines whether the internal combustion engine 101 is in a cold state, or has been warmed up, in other words, has been warmed up, based on the coolant temperature TW detected by the water temperature sensor 108.

Here, the control device 109 calculates a target intake air amount from the required torque set based on the accelerator opening ACC, and outputs an opening control signal based on the target intake air amount to the electronically controlled throttle valve 119.
Further, the control device 109 calculates the ignition timing based on engine operating conditions such as the engine load and the engine rotational speed NE, and outputs an ignition control signal to the ignition coil 107 based on the calculated ignition timing, thereby controlling the spark plug 106. Controls ignition timing.

Furthermore, the control device 109 determines the required injection amount for one combustion cycle based on the intake air flow rate QA, engine speed NE, cooling water temperature TW, air-fuel ratio, etc., and injects the required injection amount from the fuel injection valve 105. The injection pulse width for this purpose is set according to the fuel pressure at that time.
Note that the control device 109 aims to improve the exhaust properties in the cold idle state by performing split injection control and/or promoting atomization by increasing the fuel pressure in the cold idle state.

By the way, when the control device 109 performs split injection control and/or increases the fuel pressure in a cold idle state, the injection pulse width in one injection becomes shorter, and the correlation between the injection pulse width and the actual injection amount decreases. In some cases, an injection pulse width in a nonlinear region is used.
FIG. 2 is a diagram showing the correlation between the actual injection amount and the injection pulse width, the valve behavior at the injection pulse width used in the cold idle state, and the valve behavior at the injection pulse width used in the idle state after warm-up. .

Below, with reference to FIG. 2, the nonlinear region in the injection characteristics will be outlined.
When the fuel injection valve 105 opens, the movable element collides with the stator, causing a bouncing behavior of the movable element.
If the injection pulse width falls before such bounding behavior converges, the time from the fall of the injection pulse width (in other words, the valve closing control command) until the mover actually reaches the valve closing position (hereinafter referred to as (referred to as "valve closing time TVC") changes depending on the bounce behavior.

Then, as the valve closing time TVC changes, the actual valve opening time of the fuel injection valve 105 changes, resulting in variation in the actual injection amount with respect to the injection pulse width.
In this way, the region where the actual injection amount does not change linearly with respect to the injection pulse width due to the change in the valve closing time TVC due to the influence of the bound behavior is the nonlinear region. The linear region is the region where the actual injection amount changes linearly.

When the control device 109 sets the injection pulse width in the nonlinear region by performing split injection control and/or increasing the fuel pressure in the cold idle state, the required injection amount from the fuel injection valve 105 is Since different amounts of fuel are injected and the injection amount varies depending on the fuel injection valve 105, the idle rotation speed will fluctuate.
Therefore, the control device 109 corrects the injection pulse width in the nonlinear region in the cold idle state for each fuel injection valve 105 according to the injection variation, thereby suppressing the variation in the injection amount between the fuel injection valves 105. (injection pulse width correction function).

In the above-mentioned pulse width correction function, the control device 109 first calculates the valve closing time TVC when injecting with the injection pulse width TPsb used in split injection (and/or high fuel pressure) in a cold idling state during fuel injection. Detection is performed for each valve 105.
Then, based on the detected valve closing time TVC, the control device 109 generates a pulse width correction value THOS for adjusting the actual injection amount to the required injection amount, in other words, for adjusting the actual valve opening time to the required valve opening time. is learned for each fuel injection valve 105.

Note that the injection pulse width TPsb is a pulse width common to each cylinder (each fuel injection valve 105) that is not subjected to correction processing using the pulse width correction value THOS.
Then, the control device 109 corrects the injection pulse width TPsb in split injection (and/or high fuel pressure) in the cold idle state using the learned pulse width correction value THOS, and outputs an injection pulse signal having the corrected injection pulse width TPs. is output to the fuel injection valve 105.

FIG. 3 is a time chart showing one aspect of a method for detecting the valve closing time TVC.
Note that the detection method shown in FIG. 3 is a known detection method disclosed in Japanese Patent Application Publication No. 2018-084240 and the like.
Such a detection method is a method of detecting the valve closing completion timing of the fuel injection valve 105 based on the voltage change (magnetic flux density change occurring between the mover and the stator) after the injection pulse signal is turned off. By capturing the voltage change that occurs at the valve closing completion timing, for example, based on the second order differential value of the voltage, the valve closing completion timing that occurs with a delay after the injection pulse signal is turned off is detected.

When the control device 109 detects the valve closing completion timing of the fuel injection valve 105, it determines the time from the falling edge of the injection pulse signal (on→off) to the valve closing completion timing as the valve closing time TVC.
Then, the control device 109 searches the pulse width correction value THOS corresponding to the obtained valve closing time TVC by referring to the correlation table between the valve closing time TVC and the pulse width correction value THOS, and searches for the pulse width correction value THOS corresponding to the obtained valve closing time TVC. Let THOS be the injection pulse width TPsb used for detection of the valve closing completion timing and the pulse width correction value THOS applied to the fuel injection valve 105.

FIG. 4 shows an example of a correlation table between the valve closing time TVC and the pulse width correction value THOS.
In this correlation table, the standard valve closing time TVCb is used as a reference, and the pulse width correction value THOS is assigned so as to be proportional to the deviation of the actual valve closing time TVC from the standard valve closing time TVCb.

In other words, when the actual valve closing time TVC is longer than the standard valve closing time TVCb, the control device 109 sets a negative pulse width correction value THOS that reduces the injection pulse width TPs, and conversely sets a negative pulse width correction value THOS that reduces the injection pulse width TPs. When the actual valve closing time TVC is shorter than the time TVCb, a positive pulse width correction value THOS that increases the injection pulse width TPs is set.
The control device 109 sets the result of correcting the injection pulse width TPsb using the pulse width correction value THOS as the final injection pulse width TPs, so that when the fuel injection valve 105 is closed at the standard valve closing time TVCb, The valve is opened for a time equivalent to , so that the injection amount is equal to the injection amount at the standard valve closing time TVCb.

Here, the control device 109 stores the injection pulse width TPsb used in split injection (and/or high fuel pressure) in the cold idle state as a pseudo pulse width TPP, and stores the injection pulse width TPsb used in the split injection (and/or high fuel pressure increase) in the cold idle state as a pseudo pulse width TPP. A TPP injection pulse signal is output to the fuel injection valve 105.
Then, the control device 109 learns the pulse width correction value THOS to be applied to the pseudo pulse width TPP by detecting the valve closing time TVC when the valve is opened with the pseudo pulse width TPP.

After learning the pulse width correction value THOS, the control device 109 uses the learned pulse width in the idle state after warm-up when using the injection pulse width TPsb having the same pulse width as the pseudo pulse width TPP in the cold idle state. The injection pulse width TPsb is corrected using the width correction value THOS.
That is, the control device 109 learns the pulse width correction value THOS used in the cold idle state in the idle state after warming up.

In the case of cold idling, the amount of fuel injected per combustion cycle is larger than in the idling state after warming up, so the fuel pressure pulsation becomes large, and the valve closing completion timing is detected with high accuracy due to the influence of the fuel pressure pulsation. things become difficult.
Therefore, learning of the pulse width correction value THOS is preferably performed in an idling state after warm-up, when the fuel injection amount per combustion cycle is small and fuel pressure pulsation is relatively small.

However, in a cold idle state, split injection, high fuel pressure, etc. are carried out, and the required injection amount is greater than after warming up, so in the cold idle state, the injection pulse used in the cold idle state There are almost no opportunities for injection with the width TPsb.
Therefore, when normal fuel injection is performed in an idle state after warming up, there is almost no opportunity for the control device 109 to learn the pulse width correction value THOS that can be adopted in a cold idle state.

Therefore, in the idle state after warming up, the control device 109 causes fuel injection to be performed with a pseudo pulse width TPP that is the injection pulse width TPsb used in the cold idle state, and adjusts the valve closing time TVC with the pseudo pulse width TPP. By detecting this, the pulse width correction value THOS used in fuel injection control during cold idling can be learned with high accuracy.
FIG. 5 is a flowchart showing one aspect of the learning procedure for the pulse width correction value THOS, which is executed by the control device 109 (microcomputer 109a).

In step S601, the control device 109 determines whether the internal combustion engine 101 is in an idle state based on the accelerator opening degree ACC, engine rotation speed, and the like.
When the internal combustion engine 101 is in an idle state, the control device 109 proceeds to step S602 and determines whether the fuel pressure fluctuation is below a predetermined value, in other words, whether the fuel pressure is in a predetermined stable state. The determination is made based on the fuel pressure FP detected by the sensor 126.

Then, if the internal combustion engine 101 is in an idle state and the fuel pressure is stable, the control device 109 proceeds to step S603.
On the other hand, if the internal combustion engine 101 is not in an idling state, the control device 109 temporarily ends this routine after the determination process in step S601, and if the fuel pressure is fluctuating even if the internal combustion engine 101 is in an idling state, the control device 109 returns to step S602. After the determination process, this routine is temporarily terminated.

If the internal combustion engine 101 is in an idle state and the fuel pressure is stable, and the process proceeds to step S603, the control device 109 determines whether the internal combustion engine 101 is in a cold state (in other words, in the warm-up process or during warm-up). Whether this is the case is determined based on the coolant temperature TW detected by the water temperature sensor 108 or the like.
If the internal combustion engine 101 is in an idle state and a cold state, that is, in a cold idle state, the control device 109 proceeds to step S604 and subsequent steps.

In step S604, the control device 109 performs pulse width correction on the injection pulse width TPsb per injection set in the split injection (and/or high fuel pressure) in the cold idle state in the idle state after warming up. It is stored in the built-in non-volatile memory as the pseudo pulse width TPP used for learning the value THOS.
Next, in step S605 and subsequent steps, the control device 109 performs learning of the pulse width correction value THOS in the cold idle state.

In step S605, the control device 109 determines the closing completion timing of the fuel injector 105 when injecting with the injection pulse width TPsb, that is, the timing at which the fuel injector 105 actually closes in response to the valve closing control command. , is detected for each fuel injection valve 105 of each cylinder.
Next, in step S606, the control device 109 calculates the time from the fall of the injection pulse signal (valve closing control command) to the valve closing completion timing as the valve closing time TVC for each fuel injection valve 105 of each cylinder.

Then, in step S607, the control device 109 adjusts the valve closing time TVC of each fuel injection valve 105 based on the correlation between the valve closing time TVC shown in the map illustrated in FIG. 4 and the pulse width correction value THOS. Calculate the pulse width correction value THOS.
Note that when determining the pulse width correction value THOS from the valve closing time TVC, the control device 109 refers to a table for determining the pulse width correction value THOS from the valve closing time TVC, as shown in FIG. The pulse width correction value THOS corresponding to can be searched, and the pulse width correction value THOS can be calculated based on a function using the valve closing time TVC as a variable.

In the next step S608, the control device 109 determines whether the number of times the pulse width correction value THOS has been calculated is equal to or greater than a predetermined value.
If the number of calculations of the pulse width correction value THOS is less than the predetermined value, the reliability of the pulse width correction value THOS is not sufficient, and the control device 109 uses the calculated pulse width correction value THOS to correct the injection pulse width TPsb. This routine ends without taking effect.

On the other hand, if the number of calculations of the pulse width correction value THOS is equal to or greater than the predetermined value, the control device 109 proceeds to step S609.
In step S609, the control device 109 calculates the pulse width correction value THOS calculated from the previous injection operation (in other words, the previous value of the pulse width correction value THOS) and the pulse width correction value THOS calculated from the current injection operation. In other words, it is determined whether the absolute value of the deviation from the current value of the pulse width correction value THOS is less than a predetermined value.

If the absolute value of the deviation between the previous value of the pulse width correction value THOS and the current value of the pulse width correction value THOS is greater than or equal to a predetermined value, the control device 109 erroneously detects the pulse width correction value THOS (valve closing time TVC). This routine is terminated without reflecting the obtained pulse width correction value THOS in the correction of the injection pulse width TPsb.
On the other hand, if the absolute value of the deviation between the previous value of the pulse width correction value THOS and the current value of the pulse width correction value THOS is less than the predetermined value, the control device 109 determines that the learning error of the pulse width correction value THOS is sufficiently small. Then, the process proceeds to step S610, where the injection pulse width TPsb is corrected based on the learned pulse width correction value THOS.

Note that in a cold idle state, as described above, due to the influence of fuel pressure fluctuations, the learning accuracy of the pulse width correction value THOS is lower than in an idle state after warming up.
However, if the learning of the pulse width correction value THOS in the idle state after warm-up has not progressed, the control device 109 can supplementally use the pulse width correction value THOS learned in the cold idle state. Try to suppress variations in injection amount as much as possible.
In other words, the control device 109 preferentially uses the pulse width correction value THOS learned based on the pseudo pulse width TPP in the idle state after warm-up to correct the injection pulse width TPsb in the cold idle state, and When the learning in the idle state is not progressing, the learning result in the cold idle state is used supplementarily.

Next, learning of the pulse width correction value THOS in the idle state after warming up will be explained in detail.
If the control device 109 determines in step S603 that the internal combustion engine 101 is not in a cold state but in a post-warm-up state after warm-up has been completed, that is, in an idle state after warm-up, the process proceeds to step S611.

In step S611, the control device 109 reads the pseudo pulse width TPP stored in the memory in order to perform fuel injection using the injection pulse signal of the pseudo pulse width TPP in the idle state after warming up.
The pseudo pulse width TPP is the injection pulse width TPsb per injection in split injection (and/or high fuel pressure) in a cold idle state, which is stored by the control device 109 in step S604 described above.

In other words, the control device 109 performs fuel injection in the idle state after warming up with the injection pulse width TPsb used in the injection control in the cold idle state, so that the control device 109 performs fuel injection in the idle state after warming up and in the cold idle state. The injection control is reproduced and the pulse width correction value THOS used to correct the injection pulse width TPsb in the cold idle state is learned in the idle state after warming up.

Next, the control device 109 proceeds to step S612, and increases the pressure of the fuel supplied to the fuel injection valve 105 in order to inject the required injection amount in the idle state after warming up by fuel injection with the pseudo pulse width TPP. Outputs fuel pressure control signal.
Specifically, the control device 109 determines a target fuel pressure for injecting the required injection amount with the pseudo pulse width TPP from the pseudo pulse width TPP and the requested injection amount, and controls the high pressure fuel so that the actual fuel pressure becomes the target fuel pressure. A control signal for adjusting the discharge amount of the pump 125 is output.

Here, if the fuel pressure is made higher than normal, the penetration force of the fuel spray increases, and the fuel directly injected into the cylinder from the fuel injection valve 105 tends to adhere to the crown surface of the piston.
Therefore, when increasing the fuel pressure in order to inject the required injection amount with the pseudo pulse width TPP in the idle state after warming up, the control device 109 sets the injection timing of the fuel injector 105 to be lower than when the fuel pressure is normal. Get closer to dead center.
By changing the injection timing, the distance from the fuel injection valve 105 to the piston crown surface when the fuel injection valve 105 performs fuel injection increases, and the adhesion of fuel spray to the piston crown surface is suppressed.

When performing fuel injection with the pseudo pulse width TPP, the control device 109 proceeds to step S613, and similarly to step S605, detects the closing completion timing of the fuel injector 105 for each fuel injector 105 of each cylinder. do.
Next, in step S614, the control device 109 calculates the time from the fall of the injection pulse signal (valve closing control command) to the valve closing completion timing as the valve closing time TVC for each fuel injection valve 105 of each cylinder.

Then, in step S615, the control device 109 adjusts the valve closing time TVC of each fuel injection valve 105 based on the correlation between the valve closing time TVC shown in the map illustrated in FIG. 4 and the pulse width correction value THOS. Calculate the pulse width correction value THOS.
The pulse width correction value THOS obtained by the control device 109 in step S615 is a correction value applied to the pseudo pulse width TPP, which is the injection pulse width TPsb used in the split injection in the cold idle state.

That is, the control device 109 learns injection variations in split injection (and/or high fuel pressure) in a cold idle state in an idle state after warm-up.
In a cold idle state, the fuel injection amount (required injection amount) per combustion cycle is large, so it is affected by fuel pressure pulsations and it is difficult to learn the dispersion of the injection amount (valve closing time) with high accuracy.

On the other hand, in the idling state after warming up, the fuel injection amount per combustion cycle (required injection amount) is smaller than in the cold idling state, so the influence of fuel pressure pulsations is small and the variation in injection amount (valve closing completion timing) can be learned with high accuracy.
In addition, since the control device 109 increases the fuel pressure in order to inject the required injection amount with the pseudo pulse width TPP in the idle state after warming up, the speed of the movable element when the fuel injection valve 105 is closed increases. , the change in magnetic flux density when the movable element is seated is large, and the detection accuracy of the valve closing completion timing is improved.

After determining the pulse width correction value THOS in step S615, the control device 109 proceeds to step S616.
In step S616, the control device 109 determines whether the number of times the pulse width correction value THOS has been calculated is equal to or greater than a predetermined value.

If the number of calculations of the pulse width correction value THOS for the pseudo pulse width TPP is less than the predetermined value, the reliability of the pulse width correction value THOS is not sufficient, so the control device 109 calculates the calculated pulse width correction value THOS by This routine ends without saving the pulse width correction value THOS used in the cold idle state.
On the other hand, if the number of calculations of the pulse width correction value THOS is equal to or greater than the predetermined value, the control device 109 proceeds to step S617.

In step S617, the control device 109 calculates, for each fuel injector 105, the pulse width correction value THOS calculated from the previous injection operation with the pseudo pulse width TPP (in other words, the previous value of the pulse width correction value THOS), Determine whether the absolute value of the deviation from the pulse width correction value THOS (in other words, the current value of the pulse width correction value THOS) calculated from the injection operation with the current pseudo pulse width TPP is below a predetermined value. do.

If the absolute value of the deviation between the previous value of the pulse width correction value THOS and the current value of the pulse width correction value THOS is greater than the predetermined value, the pulse width correction value THOS (valve closing completion timing) may have been detected incorrectly. Therefore, the control device 109 ends this routine without storing the obtained pulse width correction value THOS as the pulse width correction value THOS used in the cold engine idle state.
On the other hand, if the absolute value of the deviation between the previous value of the pulse width correction value THOS and the current value of the pulse width correction value THOS is less than the predetermined value, the control device 109 determines that the learning error of the pulse width correction value THOS is sufficiently small. The process proceeds to step S618, and the pulse width correction value THOS calculated from the injection operation with the pseudo pulse width TPP is stored in the built-in non-volatile memory as the pulse width correction value THOS used for pulse width correction in the cold idle state. Save to.

If the pulse width correction value THOS learned in the idle state after warming up is stored in the built-in nonvolatile memory during the cold idle state, the control device 109 adjusts the injection pulse using the pulse width correction value THOS. Correct the width TPsb.
By correcting the injection pulse width TPsb, variations in the injection amount for each fuel injection valve 105 can be suppressed, and rotational fluctuations in an idling state before air-fuel ratio feedback control is started can be suppressed.

The technical ideas described in the above embodiments can be used in combination as appropriate, as long as there is no contradiction.
Further, although the content of the present invention has been specifically explained with reference to preferred embodiments, it is obvious that those skilled in the art can make various modifications based on the basic technical idea and teachings of the present invention. It is.

For example, in the process of determining the pulse width correction value THOS based on the detection result of the operating state of the fuel injection valve 105 as a fuel injection device, the control device 109 determines the valve closing completion timing (in other words, the valve opening time or valve closing time ) as an operating state, and also detects fluctuations in the idle rotational speed of the internal combustion engine 101 as the operating state of the fuel injection valve 105, and learns the pulse width correction value THOS so as to suppress fluctuations in the idle rotational speed. Can be done.
Furthermore, the control device 109 can learn the pulse width correction value THOS for each cooling water temperature category that represents the temperature of the internal combustion engine 101.

Further, the internal combustion engine 101 is not limited to a direct injection type internal combustion engine, but may also be a port injection type internal combustion engine in which a fuel injection device (fuel injection valve 105) injects fuel into the intake port 110 of the internal combustion engine 101. , the learning process of the pulse width correction value THOS of the present invention can be applied.
In addition, the pseudo pulse width TPP is stored in advance as a design value in a non-volatile memory built into the control device 109, and the control device 109 stores the design value stored in the non-volatile memory in an idle state after warming up. The pulse width correction value THOS can be learned by injecting with the pseudo pulse width TPP as shown in FIG.

Further, the control device 109 calculates a pulse width correction value THOS used for pulse width correction in a cold engine idle state and stores it in a non-volatile memory, and then combines the newly calculated pulse width correction value THOS with the stored pulse width. By updating the memory value when the deviation from the correction value THOS exceeds a predetermined value, it is possible to cope with deterioration over time of the fuel injection valve 105 (change over time in injection variation characteristics).
Further, the control device 109 can perform averaging processing such as weighted averaging on the pulse width correction value THOS, and perform pulse width correction using the pulse width correction value THOS after the averaging processing.

101... Internal combustion engine, 105... Fuel injection valve (fuel injection device), 109... Control device (fuel injection control device)

Claims (5)

A fuel injection control device for an internal combustion engine, which acquires information regarding the operating state of the internal combustion engine and outputs an injection pulse signal to a fuel injection device that injects fuel into the internal combustion engine,
storing a pulse width of the injection pulse signal in a cold engine idle state as a pseudo pulse width;
detecting the operating state of the fuel injection device when injecting the required injection amount with the pseudo pulse width in an idling state after warming up;
Determining a pulse width correction value based on the detection result of the operating state,
correcting the pulse width of the injection pulse signal with the pulse width correction value in a cold engine idle state;
Fuel injection control device for internal combustion engines. The fuel injection control device for an internal combustion engine according to claim 1,
Split injection is carried out in which fuel injection is divided into multiple times per combustion cycle in a cold idle state,
The pseudo pulse width is a pulse width per time in the split injection,
Fuel injection control device for internal combustion engines. The fuel injection control device for an internal combustion engine according to claim 1,
The operating state of the fuel injection device is an actual valve opening time with respect to the pseudo pulse width,
Fuel injection control device for internal combustion engines. The fuel injection control device for an internal combustion engine according to claim 1,
In an idle state after warming up, when injecting the required injection amount with the pseudo pulse width, the pressure of the fuel fed to the fuel injection device is set to a pressure at which the required injection amount is injected with the pseudo pulse width. Outputs fuel pressure control signal for adjustment,
Fuel injection control device for internal combustion engines. The fuel injection control device for an internal combustion engine according to claim 4,
The fuel injection device injects fuel directly into the cylinder of the internal combustion engine,
When performing the fuel injection with the pseudo pulse width by increasing the pressure of the fuel fed to the fuel injection device, the injection timing by the fuel injection device is brought closer to the bottom dead center of the piston.
Fuel injection control device for internal combustion engines.