JP2007332923A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device for an internal combustion engine capable of reducing emission of a noxious gas component of exhaust gas components, while securing a smooth and excellent startability of the device at any time. <P>SOLUTION: The fuel injection control device for the internal combustion engine supplies a fuel by injection, after an injection basic quantity of the fuel is calculated, at least based on engine revolutions per unit time. The fuel injection control device monitors a change in the engine revolutions corresponding to each step of a fuel injection supply after a fuel injection quantity is calculated, under a predetermined engine starting condition that includes a step of a fuel injection supply at a starting time, in which the engine revolutions per unit time is not more than a predetermined value. Then, the fuel injection control device learns, on an injection to injection basis, a fuel injection quantity in each step, in which the fuel injection quantity is controlled so that a change in the engine revolutions is within a predetermined range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine that performs fuel injection control at the time of startup of the internal combustion engine, and in particular, fuel injection at start-up or fuel injection after start ( The present invention relates to a technique for optimally controlling the fuel injection amount for each cylinder and ensuring smooth startability in the process of (until the end of fuel injection at start-up).

  In an internal combustion engine, for example, a multi-cylinder internal combustion engine, sensors for detecting engine coolant temperature, engine speed, etc. are provided, and a basic fuel injection amount is calculated based on at least the engine speed per unit time of the multi-cylinder internal combustion engine. In some cases, a fuel injection control device having a control means for injecting and supplying fuel after calculation is provided.

Japanese Patent No. 3449170 Japanese Patent No. 3498392

By the way, the correction of the injection amount at the start in the conventional fuel injection control device of the internal combustion engine is performed by uniformly increasing or decreasing the injection amount in the next start period based on the engine information in the previous start period. ing.
At this time, when further aiming at an emission reduction effect, it is important to grasp the required injection amount for starting the internal combustion engine for each injection.
However, the current situation is that the required injection amount required for starting the internal combustion engine cannot be grasped for each injection, and improvement has been desired.

  An object of the present invention is to realize a fuel injection control device for an internal combustion engine that reduces emission of harmful gas components out of exhaust gas components while always ensuring good and smooth startability.

  Accordingly, in order to eliminate the above-described disadvantages, the present invention provides a fuel injection control apparatus for an internal combustion engine that supplies fuel after calculating a basic fuel injection amount based on at least the engine speed per unit time. Monitor the amount of change in the engine speed corresponding to each stroke in which the injection is supplied after calculating the fuel injection amount under predetermined engine starting conditions including the process of fuel injection at start-up when the engine speed is less than the predetermined value. The fuel injection amount for each stroke in which the injection is supplied is learned for each injection so that the amount of change in the engine speed falls within a predetermined range.

As described above in detail, according to the present invention, in the fuel injection control device for an internal combustion engine that supplies fuel after calculating the basic injection amount of fuel based on at least the engine speed per unit time, the engine per unit time Monitoring the amount of change in the engine speed corresponding to each stroke in which the injection is supplied after calculating the fuel injection amount under predetermined engine starting conditions including the process of fuel injection at start-up when the rotational speed is less than or equal to a predetermined value; The fuel injection amount for each stroke in which the injection is supplied is learned for each injection so that the amount of change in the engine speed falls within a predetermined range.
As a result, the excess / shortage of the fuel can be grasped in detail based on the rotation change, and the optimum fuel injection amount can be obtained.

  By inventing as described above, under a predetermined engine starting condition, the amount of change in the engine speed corresponding to each stroke is monitored, and the injection is supplied so that the amount of change in the engine speed falls within a predetermined range. The fuel injection amount of the stroke is learned for each injection, and the optimum fuel injection amount is determined by grasping the excess / deficiency of the fuel in detail based on the rotation change.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 6 show an embodiment of the present invention.
In FIG. 2, reference numeral 1 is a fuel injection control device for an internal combustion engine, and 2 is a control means ("ECM") for injecting and supplying fuel after calculating a basic fuel injection amount based on at least the engine speed per unit time of the multi-cylinder internal combustion engine. Is also called.).

On the input side of the control means 2, as shown in FIG. 2, a water temperature sensor 3 capable of detecting the cooling water temperature, a cam angle sensor 4 capable of detecting the engine speed (also referred to as “engine speed”), Pressure sensor 5 capable of detecting intake pipe pressure, throttle sensor 6 capable of detecting throttle opening, intake air temperature sensor 7 capable of detecting intake air temperature, vehicle speed sensor 8 capable of detecting vehicle speed, and ON / OFF of the air conditioner An air conditioner switch (also referred to as “air conditioner SW”) 9 that detects an OFF state and outputs an air conditioner ON / OFF signal, and a shift switch (“ 10) and an air-fuel ratio sensor capable of detecting the air-fuel ratio (also referred to as “A / F sensor”. Alternatively, it can also be referred to as a rear oxygen sensor). When a battery 12 for outputting a battery voltage signal, a detectable atmospheric pressure sensor 13 of the atmospheric pressure, provided by connecting the VSV driving detecting unit 14 that detects a canister purge VSV driving signal.
Further, a fuel injector 15 is connected to the output side of the control means 2.

At this time, as shown in FIG. 2, the control means 2 calculates a basic injection time calculation unit 16 for starting basic injection time, a basic injection time calculation unit 17 for calculating basic injection time, and an injection time. An injection time calculation unit 18 for calculating, and a correction unit 19 for correcting are provided. The water temperature sensor 3 is connected to the starting basic injection time calculation unit 16 and the correction unit 19 of the control unit 2.
The cam angle sensor 4 is connected to the basic injection time calculation unit 17 and the correction unit 19 of the control unit 2.
Further, in addition to the water temperature sensor 3 and the cam angle sensor 4, the correction unit 19 includes a pressure sensor 5, a throttle sensor 6, an intake air temperature sensor 7, a vehicle speed sensor 8, an air conditioner switch 9, a shift switch 10, an air-fuel ratio sensor 11, The battery 12, the atmospheric pressure sensor 13, and the VSV drive detection unit 14 are connected and provided.

A basic injection time calculation unit 17, a starting basic injection time calculation unit 16, and a correction unit 19 of the control unit 2 are connected to the injection time calculation unit 18.
The fuel injector 15 is connected to the injection time calculating unit 18.

The control means 2 of the fuel injection control device 1 of the internal combustion engine performs control to inject and supply fuel after calculating a basic fuel injection amount based on at least the engine speed per unit time.
That is, the control means 2 controls the injection timing and the injection time (also referred to as “injection amount”) of the fuel injected from the fuel injector 15 to inject the optimal amount of fuel at the optimal timing. The injection control is performed.
In this fuel injection control, the fuel injection timing and the fuel injection time are determined by the start-time injection control that is executed when the internal combustion engine is started and the post-start-up injection control that is executed during normal operation.
Further, fuel cut control is performed according to the operating state of the internal combustion engine.

Here, the fuel injection control will be described.
The start-up injection control is performed by the configuration disclosed in FIG.
As for the fuel injection timing, when the first cam angle signal (BTDC 5 degrees) is detected after the cylinder determination, the injection is performed once for all the cylinders only once.
Thereafter, the one-time injection is stopped, and the process proceeds to the sequential injection.
Further, the fuel injection time of the injection time calculation unit 18 is the basic injection time at the start from the basic injection time calculation unit at the start 16 determined by the coolant temperature, the intake pipe pressure correction from the correction unit 19 and the engine rotation. It is determined by adding various corrections such as numerical (also referred to as “engine speed”) correction and throttle opening correction.
The starting basic injection time in the starting basic injection time calculation unit 16 is such that the lower the cooling water temperature is, the longer the injection time is and the starting performance is improved.

Synchronous injection and asynchronous injection are performed at the fuel injection timing in the post-startup injection control.
In synchronous injection, the injection start timing is calculated so that the set injection end timing is reached in normal times, and sequential injection is performed.
The injection end timing is determined by the engine speed from the cam angle sensor 4 and the intake pipe pressure from the pressure sensor 5.
Asynchronous injection does not synchronize with the engine speed, which is a cam angle sensor signal from the cam angle sensor 4, at the time of deceleration fuel cut recovery, sudden acceleration, etc., but temporarily injects in synchronization with the immediately preceding cylinder. .
The basic injection time is determined by the basic injection time calculation unit 17 based on the intake pipe pressure from the pressure sensor 5 and the engine speed from the cam angle sensor 4 as the fuel injection time in the post-startup injection control. The following correction based on the signal from each sensor is added to the injection time to determine the optimum fuel injection time according to the operating state of the internal combustion engine.
Corrections include voltage correction, water temperature correction, increase correction immediately after start-up, throttle opening correction, D-range shift correction, air-fuel ratio feedback correction, air-fuel ratio learning correction, intake air temperature correction, purge concentration correction, atmospheric pressure correction, and high temperature restart. There is correction, acceleration increase deceleration deceleration decrease correction.

At this time, the control means 2 of the fuel injection control device 1 of the internal combustion engine performs a predetermined engine start including a start-up fuel injection process in which the engine speed per unit time is equal to or less than a predetermined value (determination speed after start). Under each condition, each process of monitoring the amount of change in the engine speed corresponding to each process of supplying the injection after calculating the fuel injection amount, and supplying the injection so that the amount of change in the engine speed falls within a predetermined range It has a function of learning the fuel injection amount at (timing) for each injection.
More specifically, the predetermined value is a post-startup determination engine speed, that is, an engine speed indicating “first explosion” described later.
The predetermined range is a range set by the lower limit guard value X1 and the upper limit guard value X2 larger than the lower limit guard value X1, that is,
X1 <Δne [i] <X2
Δne [i]: Change amount of the engine speed (in other words, “engine speed increase degree”)
It is.
The engine start condition is a range of a stroke in which continuous fuel injection is performed from the first fuel injection to the first predetermined number of fuel injections.
In addition, the fuel injection amount for each stroke is learned for each injection and optimized in units of one injection, instead of applying a constant increase or decrease correction to all the injection amounts within the start-up period when starting fuel injection. Is intended.
In other words, as shown in FIG. 5, the internal combustion engine has a suction stroke, a compression stroke, an expansion stroke in which an explosion is performed, and an exhaust stroke, in which fuel injection is performed. The injection and the explosion are approximately 360 degrees in crank angle. There is a gap.
At this time, in the multi-cylinder internal combustion engine (the disclosed example is a case of four cylinders), as shown in FIG. 6, the steps from the intake stroke to the compression stroke, the expansion stroke, and the exhaust stroke are set for each cylinder.

Further, the control means 2 of the fuel injection control device 1 of the internal combustion engine, as shown in the processes (106) and (108) in FIG. 1, when the amount of change in the engine speed deviates from a predetermined range to the increasing side, It has a function of updating the learning value of the starting injection amount for each injection by reducing the amount.
On the other hand, when the change amount of the engine speed deviates from the predetermined range to the decreasing side, the learning value of the starting injection amount for each injection is increased and corrected as shown in the processes (104) and (105) of FIG. Have the function to update.
It also has a function of setting a guard value (see “lower limit guard value X1” and “upper limit guard value X2” above) that restricts the range of the learning value to be updated.

Here, a description will be given of the reduction and the increase correction of the injection amount at the start for each injection.
The start of injection is when cylinder discrimination is completed, and the injection is executed using that as a trigger.
That is, as shown in FIG. 3, the injection start is “1”, and an arbitrary number of times before the engine speed (also referred to as “E / G speed”) reaches a peak is “n”.
Then, each time, the engine speed increase degree Δne [k] is calculated by the following equation.
Δne [k] = ne [k] −ne [k−1]
Each time, it has a learning value a [k].
When the engine speed increase Δne [k] is smaller than the predetermined value b, the amount of increase is corrected as follows.
a [k] = 1.00 + g
g: Increase correction amount When the engine speed increase Δne [k] is larger than the predetermined value c, the decrease correction is performed as follows.
a [k] = 1.00-f
f: Reduction correction amount When the engine speed increase Δne [k] is between the predetermined value b and the predetermined value c, the correction is not performed as follows.
a [k] = 1.00
Furthermore, the next start injection amount is the following equation (injection amount of control without learning) Xa [k] at the k-th time
Therefore, if the learning value a [k] is updated, the optimum value of the internal combustion engine is obtained.

That is, as shown in FIG. 4, when the engine speed increase Δne [2] is large (exceeding the standard range), the following expression a [2-m] = 1.00−f
m: The weight reduction is corrected by a number smaller than the number of cylinders.
Further, when the engine speed increase Δne [5] is small (because it is negative, it is rather a stalled state), the following equation a [5-m] = 1.00 + g
m: The amount of increase is corrected by a number smaller than the number of cylinders.

Further, the control means 2 of the fuel injection control device 1 for the internal combustion engine sets a second predetermined number smaller than the first predetermined number, and omits the number of strokes from the first to the second predetermined number. And learning (masking).
Here, “masking one to several times so that the time from the start of injection to the first explosion does not increase” means that if the weight loss correction proceeds too much due to mislearning, a lean mixture will be formed. It takes longer to get a bomb.
This can be considered as a deterioration of the startability, and it is to prevent learning at the beginning of the start so as not to cause such problems.

That is, in this embodiment, it is assumed that “the first explosion always occurs at the same location every time counting from the start of injection”.
If the water temperature is about 25 ° C., the initial explosion timing is almost the same.
Further, the amount of change in engine speed, which is the degree of increase in engine speed at each injection, is calculated, and the learning for that time is updated based on the amount of change in engine speed.
Further, the injection amount within the next start-up period becomes the injection amount including learning, and becomes an optimum value as learning progresses.
Even if the timing of the first explosion is shifted, if the learning update amount at one time is small, it is possible to reduce the point at which the injection amount is desired to be reduced by repeating the number of start-ups.

An example of implementation will be described.
As shown in FIGS. 3, 4, and 6, when the counter (N = 1 to 20) is counted for each injection from the start of injection, the learning values a [1], a [2], a [3], a [4], a [5], ..., a [20] are provided in advance.
Then, for example, when the engine rotation fluctuation rate (which can also be referred to as “amount of change in engine speed”) is large, that is, when the first predetermined number is N = 10, it is desired to reduce the amount as shown in FIG. In the case of four cylinders, the point is between N = 6 and N = 10, that is, N = 7, 8, and 9.
That is, in the case of four cylinders, the learning values a [7], a [8], and a [9] may be corrected by reducing the amount.
When the timing is N = 10 and there are three cylinders, the point to be reduced is between N = 7 and N = 10, that is, N = 8, 9, and the learning values a [8], a [9 ] May be corrected by reducing the amount.

The “first explosion” is a phenomenon in which cranking starts, injection and ignition progress, ignition occurs for the first time, and an engine speed higher than the cranking speed is generated.
If the second predetermined number of times is set to N = 4, which is smaller than the first predetermined number of N = 10, the timing of the initial explosion is between learning values a [1] to a [3]. If there is, it is between the first time and the second predetermined number N = 4, so learning is omitted, that is, updating is prohibited.
This is because the initial explosion may be between N = 6 and N = 9 if the weight loss update progresses too much.
At this time, by always fixing the injection amount necessary for the first explosion, it is possible to improve the stability in the subsequent correction of the injection amount.

  Next, the operation will be described along the control flowchart of the fuel injection control device 1 of the internal combustion engine.

When the control program of the fuel injection control device 1 of the internal combustion engine starts (101), the control means 2 inputs a cooling water temperature signal from the water temperature sensor 3, and the water temperature at the start is within a predetermined range, that is, T1 <start Water temperature <T2
T1: Water temperature lower limit value T2: Transition to determination (102) of whether or not the water temperature upper limit value is reached.
When this determination (102) is YES, the engine speed increase degree Δne [i] is expressed by the following expression: Δne [i] = ne [i] −ne [i−1]
The process proceeds to the process (103) calculated by the above.
If the determination (102) is NO, the process proceeds to determination (111) as to whether or not an ignition switch (also referred to as “IG”), which will be described later, is in an OFF state.

The above engine speed increase Δne [i] is expressed by the following equation: Δne [i] = ne [i] −ne [i−1]
After the process (103) calculated by the above, the engine speed increase Δne [i] is less than the lower limit guard value X1, that is, Δne [i] <X1
It shifts to judgment (104) of whether it is.
If this determination (104) is YES, the process proceeds to the process (105) for obtaining the provisional learning value A [i].
In this process (105), the formula A [i] = B [i] + C
B [i]: Learning value C: A provisional learning value A [i] is obtained by an increase coefficient.
When the determination (104) is NO, the engine speed increase Δne [i] is within a predetermined range, that is, X1 <Δne [i] <X2.
X2: The process proceeds to determination (106) as to whether or not the upper limit guard value is reached.

The engine speed increase degree Δne [i] is within a predetermined range, that is, X1 <Δne [i] <X2.
If the determination (106) is YES in the determination (106) of whether or not there is, the expression A [i] = B [i]
Thus, the process proceeds to the process (107) for obtaining the provisional learning value A [i].
If the determination (106) is NO, the formula A [i] = B [i] -D
D: The process proceeds to the process (108) for obtaining the provisional learning value A [i] using the weight loss coefficient.
And after calculating | requiring the temporary learning value A [i] by the above-mentioned process (105), a process (107), and a process (108), in order to make a new value by performing "+1" to the injection count COUNT to learn, COUNT = COUNT + 1
Then, the process proceeds to the process (109) for obtaining the injection count COUNT learned.

After obtaining the injection count COUNT to be learned in the process (109), whether the learned injection count COUNT exceeds N, that is, COUNT> N
It shifts to judgment (110) of whether it is.
When this determination (110) is NO, the above engine speed increase Δne [i] is expressed by the following equation: Δne [i] = ne [i] −ne [i−1]
The process returns to (103) calculated by
If the determination (110) is YES, the process proceeds to determination (111) as to whether or not the ignition switch is OFF.

In the determination (111) of whether or not the ignition switch is in the OFF state, if the determination (111) is NO, the determination is repeated until the determination (111) becomes YES.
If the determination (111) is YES, the process proceeds to the “self-shutdown” process (112).
The term “during self-shutdown” means that driving of the engine, auxiliary equipment, etc. is stopped, and then only the control means (also referred to as “ECM”) 2 remains in the activated state, and the control means 2 performs calculation, Processing such as storage is possible.

Then, after the “in self-shutdown” process (112), whether the number of injections COUNT to be learned exceeds N, that is, COUNT> N
It shifts to judgment (113) of whether it is.
If this determination (113) is YES, whether the engine stop water temperature exceeds a predetermined value T3, that is, the engine stop water temperature> T3.
It shifts to judgment (114) of whether it is.
When determination (113) is NO, it transfers to the process (115) which does not update learning value B [i].
That is, in this process (115), the value learned previously is left as is, and the formula A [i] = B [i]
To return the provisional learning value A [i] to the previously learned value, and the number of injections COUNT to be learned is
COUNT = 0
And

Also, whether the water temperature when the engine is stopped exceeds a predetermined value T3, that is, the water temperature when the engine is stopped> T3
If the determination (114) is YES in the determination (114) of whether or not, the process proceeds to processing (116) for updating the learning value B [i].
In this processing (116), the formula B [i] = A [i]
Holds the temporary learning value A [i], and the number of injections COUNT to be learned is
COUNT = 0
And
When judgment (114) is NO, it transfers to the process (115) which does not update learning value B [i].

  Then, after the process (115) for not updating the learning value B [i] and the process (116) for updating the learning value B [i], the process proceeds to the end (117).

  Thereby, the control means 2 of the fuel injection control device 1 of the internal combustion engine performs a predetermined engine start including a start-up fuel injection process in which the engine speed per unit time is equal to or less than a predetermined value (determination speed after start). Under each condition, each process of monitoring the amount of change in the engine speed corresponding to each process of supplying the injection after calculating the fuel injection amount, and supplying the injection so that the amount of change in the engine speed falls within a predetermined range By learning the fuel injection amount for each injection, it is possible to grasp in detail the excess or deficiency of the fuel based on the rotation change, and to obtain the optimum fuel injection amount.

  Further, the control means 2 of the fuel injection control device 1 of the internal combustion engine corrects the learning value of the starting injection amount for each injection by decreasing the amount of change in the engine speed when it deviates from a predetermined range. And a function to increase and correct the learning value of the starting injection amount for each injection when the amount of change in the engine speed deviates from a predetermined range. By having a function of setting a guard value that regulates the range of learning values to be updated, more accurate and stable startability can be obtained if the number of updates increases.

  Further, the control means 2 of the fuel injection control device 1 for the internal combustion engine sets a second predetermined number of times less than the first predetermined number of times, and omits the counting of the number of strokes from the first time to the second predetermined number of times. Therefore, it is possible to selectively secure learning in a more important range. In addition, the amount of data can be reduced.

  The present invention is not limited to the above-described embodiments, and various application modifications are possible.

  For example, after calculating the fuel injection amount in the process of fuel injection at start-up when the engine speed is equal to or less than a predetermined value (determination speed after start-up), the fuel injection control device for an internal combustion engine described in the embodiment of the present invention It is also possible to adopt a special configuration applied to a fuel injection control device that can stop injection supply.

3 is a flowchart for control of a fuel injection control device for an internal combustion engine showing an embodiment of the present invention. It is a schematic block diagram of the fuel-injection control apparatus of an internal combustion engine. It is a time chart of the fuel-injection control apparatus of an internal combustion engine. It is a time chart when Δne [2] is large and Δne [5] is small. It is a schematic explanatory drawing which shows that there is a shift of about 360 degrees in crank angle between the suction stroke (injection) and the expansion stroke (explosion). It is a figure which shows arrangement | positioning of each stroke in a 4-cylinder engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection control apparatus of internal combustion engine 2 Control means (it is also called "ECM")
3 Water temperature sensor 4 Cam angle sensor 5 Pressure sensor 6 Throttle sensor 7 Intake air temperature sensor 8 Vehicle speed sensor 9 Air conditioner switch (also described as “air conditioner SW”)
10 Shift switch (also referred to as “shift SW”)
11 Air-fuel ratio sensor (also described as “A / F sensor”, or in other words, a rear oxygen sensor)
DESCRIPTION OF SYMBOLS 12 Battery 13 Atmospheric pressure sensor 14 VSV drive detection part 15 Fuel injector 16 Basic injection time calculating part 17 Basic injection time calculating part 18 Injection time calculating part 19 Correction | amendment part

Claims (3)

  In a fuel injection control device for an internal combustion engine that supplies fuel after calculating a basic fuel injection amount based on at least the engine speed per unit time, fuel injection at start-up when the engine speed per unit time is a predetermined value or less Under a predetermined engine starting condition including the process, the amount of change in the engine speed corresponding to each stroke in which the injection is supplied after the fuel injection amount is calculated is monitored so that the amount of change in the engine speed falls within a predetermined range. A fuel injection control device for an internal combustion engine, which learns the fuel injection amount of each stroke for supplying fuel to each injection.   The engine start condition is a range of a stroke in which continuous fuel injection is performed from the first fuel injection to the first predetermined number of times of fuel injection, and the change amount of the engine speed deviates from the predetermined range to the increasing side. While the learning value of the starting injection amount for each injection is corrected and reduced, the learning value of the starting injection amount for each injection is updated when the amount of change in the engine speed deviates from a predetermined range. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein a guard value that restricts a range of learning values to be updated is set by correcting the increase and updating.   3. The learning according to claim 1, wherein a second predetermined number of times less than the first predetermined number of times is set, and the number of strokes is learned by omitting a period between the first time and the second predetermined number of times. A fuel injection control device for an internal combustion engine.

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