JP2536617B2 - Fuel supply amount control method during acceleration of internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel supply amount control method during acceleration of an internal combustion engine.

(Prior Art) The amount of fuel supplied to an internal combustion engine is determined according to the engine speed and the engine load such as intake air amount, intake negative pressure, throttle opening, etc. There is known a fuel supply amount control method in which the fuel amount corrected in accordance with the above is injected and supplied to the engine by the fuel injection valve.

In such a fuel supply amount control method, when the throttle valve is widely opened to accelerate the engine, the fuel supply amount is on the rich side (the air-fuel ratio is on the fuel rich side of the theoretical air-fuel ratio) so as to obtain a high output. Value (for example, 12 to 1 at air-fuel ratio
It is set to 3). When the air-fuel ratio is set to a value on the rich side, the exhaust gas temperature tends to rise, and particularly when the throttle valve is fully opened, there is a risk that the upper limit temperature allowed for the exhaust valve and the exhaust manifold will be exceeded. Therefore, when operating the engine in such an operating region, considering the durability of the engine, the air-fuel ratio is set to a value on the rich side (for example, about 10 in the air-fuel ratio), and the latent heat of vaporization of the fuel is set. Is used to prevent the temperature from exceeding the above limit temperature. In particular,
In an engine equipped with a turbocharger or other supercharger, as described above, it is necessary to set a wide operating range in which the air-fuel ratio should be set to a value on the rich side due to exhaust temperature limitation.

(Problems to be solved by the invention) However, if the air-fuel ratio during acceleration is set to a value on the rich side of the optimum value, the output required for acceleration cannot be obtained, or the fuel consumption (fuel consumption) is large, Exhaust gas characteristics also deteriorate.

The present invention has been made in order to solve such a problem, and a high output can be obtained without exerting a thermal adverse effect on an exhaust valve, an exhaust manifold, etc. at the time of acceleration of an internal combustion engine, and a fuel consumption characteristic can be obtained as an exhaust gas characteristic. It is an object of the present invention to provide an excellent fuel supply amount control method.

(Means for Solving the Problems) According to the present invention in order to achieve the above-mentioned object, when an internal combustion engine is operated in a predetermined acceleration operation range in which exhaust gas temperature is to be regulated, the internal combustion engine is supplied to the engine. The fuel amount is set in accordance with the engine speed and the magnitude of the load so that the air-fuel ratio of the air-fuel mixture is on the fuel rich side of the theoretical air-fuel ratio, and is supplied to the internal combustion engine based on the set fuel amount. When the internal combustion engine detects that the internal combustion engine has entered the predetermined acceleration operation range when controlling the fuel amount, the engine speed and the load are increased from the time when the internal combustion engine is detected until the predetermined period ends. In the fuel supply amount control method at the time of acceleration of the internal combustion engine that corrects the fuel amount set according to the amount of decrease by correcting the air-fuel ratio to the fuel lean side, from the time when the rush to the acceleration region is detected. The prescribed A procedure for detecting the passage of a period until the end of the period, and the fuel amount reduced and corrected at the start of the predetermined period, the fuel set according to the engine speed and the magnitude of the load at the end of the predetermined period When returning to the fuel amount, a procedure for setting the fuel amount to be changed according to the elapsed time of the detected period is included, and the rate of change of the fuel amount in the vicinity of the start time of the predetermined period is in the vicinity of the end time of the predetermined period. The fuel supply amount control method at the time of acceleration of the internal combustion engine is provided, wherein

Preferably, the ignition timing is retarded according to the passage of the detected period.

Note that throughout the present specification, "lean air-fuel ratio" means
It does not necessarily mean that the air-fuel ratio is set to a value closer to the fuel lean side than the stoichiometric air-fuel ratio, but means that the air-fuel ratio is set to a value leaner to the fuel lean side than a certain value.

(Function) Considering the case where the engine is operated for a long time in a predetermined acceleration operation range where the exhaust temperature of the engine should be regulated, the fuel amount supplied to the engine is an optimum value for obtaining the maximum output of the air-fuel ratio. The value is set to a value on the richer side so that the exhaust valve and the exhaust manifold are not adversely affected by heat. However, when the engine is operated for a short time in the predetermined acceleration operation range as described above, the exhaust gas temperature is
Even if the exhaust gas temperature upper limit value, which is set assuming the operation for a long time, is exceeded for a short time, there is no concern that the exhaust valve or the exhaust manifold will be thermally adversely affected.

The present invention is based on such recognition. When it is detected that the internal combustion engine plunges into the predetermined acceleration operation range, the engine speed is from the time when the plunge is detected until the predetermined period ends. Also, the fuel amount set according to the magnitude of the load is reduced and corrected, and the air-fuel ratio is made lean.

At this time, the lean degree of the air-fuel ratio is set to a value at which the maximum output is obtained immediately after the internal combustion engine has entered the above-described predetermined acceleration operation region, and then the lean degree is gradually reduced,
It is preferable to set the lean degree to 0 when the number of engine revolutions reaches a predetermined value. The method of gradually reducing the lean degree is appropriately set to a gradient depending on the type of engine and the like.

Further, preferably, the ignition timing is retarded according to the lean degree of the air-fuel ratio described above, and the output characteristics and the exhaust gas characteristics are optimized.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an engine control apparatus for carrying out the method of the present invention. In the figure, reference numeral 1 is, for example, a 4-cylinder gasoline engine, and an intake manifold 2 is connected to each cylinder of the engine 1, and an intake manifold is provided. 2 is connected to the intake pipe 3 via a surge tank 2a. An air cleaner 4 is attached to the end of the intake pipe 3 open to the atmosphere, and a throttle valve 5 is arranged in the middle of the air cleaner 4.

Each cylinder 1a of the engine 1 is provided with an ignition plug 9 for igniting an air-fuel mixture in the cylinder 1a. The ignition plug 9 is provided in the electronic control unit 10 via a distributor 16, an ignition coil 17, and a drive circuit 18. It is connected to the output side. The drive circuit 18 supplies a primary voltage to the ignition coil 17 in response to a control signal supplied from the electronic control unit 10, and the ignition coil 17 generates a secondary high voltage when the supply of the primary voltage is stopped.

A fuel injection valve 20 attached to the intake manifold 2 of each cylinder 1a is electrically connected to the output side of the electronic control unit 10. The fuel injection valve 20 is driven by a valve opening drive signal from the electronic control unit 10. The valve is opened to inject and supply a required amount of fuel according to the engine operating state to each cylinder 1a.

On the input side of the electronic control unit 10, various sensors for detecting the engine operating state, for example, a throttle opening sensor 22 for detecting the valve opening of the throttle valve 5 and a surge tank 2a are attached to the input side of the throttle valve 5. Negative pressure sensor 24 for detecting intake negative pressure, cooling water temperature sensor 26 for detecting cooling water temperature of engine 1, and attached to distributor 16,
A crank angle sensor 28 for detecting a predetermined crank angle position of a crankshaft (not shown), an atmospheric pressure sensor for detecting atmospheric pressure, an intake air temperature sensor for detecting intake air temperature, etc. are connected.

It should be noted that the electronic control unit 10 includes the above-mentioned crank angle sensor 28
The engine speed Ne can be detected from the time interval for detecting the predetermined crank angle position described above, and the number of rotations N of the engine 1 can be detected from the number of times the predetermined crank angle position is detected.

Next, a fuel supply amount control procedure and an ignition timing control procedure of the engine 1 by the electronic control unit 10 will be described.

First, the electronic control unit 10 calculates the valve opening time T _OUT of the fuel injection valve 20 according to the following equation (1) according to the operating state of the engine 1 detected by the various sensors described above.

T _OUT = T _B × K 1 × K _AFWOT + Tv (1) where T _B is the basic valve opening time, which is detected by the engine speed Ne detected by the crank angle sensor 28 and the negative pressure sensor 24 described above. According to the intake negative pressure Pb, the basic valve opening time map stored in advance in the storage device (not shown) of the electronic control unit 10 is read. K _AFWOT is a lean correction coefficient at the time of acceleration according to the present invention, the details of which will be described later. K1 is another correction coefficient such as engine cooling water temperature, atmospheric pressure, intake air temperature, and Tv is a battery correction value set according to the battery voltage.

FIG. 5 shows the above-mentioned basic valve opening time map stored in the storage device of the electronic control unit 10. The basic valve opening time T _{Bij is associated} with each engine speed value Ne _i and the intake negative pressure value Pb _j. The value is stored and the basic valve opening time according to the detected engine speed Ne and the intake negative pressure Pb by the known 4-point interpolation method.
T _B is calculated.

Here, FIG. 3 shows the engine operating region divided by the engine speed Ne and the load (intake negative pressure Pb), and the hatched portion in FIG. 3 indicates a predetermined acceleration at which the exhaust temperature should be regulated below a predetermined value. Indicates the operating area. The map value T _{Bij in} FIG. 5 set corresponding to the predetermined acceleration operation region is a value necessary for cooling the exhaust system of the engine 1 by the latent heat of vaporization of the fuel, for example, the air-fuel ratio is about 10. Is set to

The electronic control unit 10 calculates the valve opening time calculated as described above.
Based on T _OUT , the valve opening drive signal is supplied to the fuel injection valve 20 of the cylinder to which the fuel should be injected and supplied this time, and the fuel amount corresponding to the valve opening time T _OUT is injected and supplied to the cylinder.

On the other hand, the electronic control unit 10 calculates the ignition timing θig based on the following equation (2).

_θig = θ _B + Δθ ₁ + Δθ _RDWOT (2) Here, θ _B is the basic ignition timing, and like the basic valve opening time T _OUT , the basic value stored in advance in the storage device of the electronic control unit 10. From the ignition timing map, the engine speed Ne detected by the crank angle sensor 28 and the negative pressure sensor
It is read according to the intake negative pressure Pb detected by 24.
The basic ignition timing map value in a predetermined acceleration operation region shown in FIG. 3, the optimum corresponds to the basic valve opening time T _B which is set in this region, the air-fuel ratio obtained by the basic valve opening time T _B Is set to any value. Δθ ₁ is an advance or retard correction value set by the engine coolant temperature detected by the coolant temperature sensor 26, the intake temperature detected by the intake temperature sensor, the knock intensity detected by the knock sensor, and the like, Δθ _RDWOT is a correction value according to the present invention, and as will be described later in detail, it is set to a value that _retards the ignition timing according to the degree of leaning of the air-fuel ratio set during acceleration operation.

The electronic control unit 10 controls the ignition timing θig set in this way.
Based on the above, an ignition control signal is supplied to the drive circuit 18 described above, and the air-fuel mixture in the cylinder to be ignited this time is ignited at the calculated ignition timing θig.

Next, with reference to FIG. 2, the acceleration leaning coefficient calculation routine executed by the electronic control unit 10 will be described.

This routine is executed every time the crank angle sensor 28 detects the predetermined crank angle position, and the electronic control unit 10 firstly executes the engine 1 in step S10.
Determines whether the vehicle is operating in the above-described predetermined acceleration operation range. This judgment is based on the detected engine speed value.
This is performed depending on whether Ne and the intake negative pressure value Pb are values in the shaded area shown in FIG.

If the determination result is negative (No), that is, if the engine 1 is not operating in the above-described predetermined acceleration operation region, a program variable (engine speed) N described below is reset to 0 in step S11, and in step S12. Leaning coefficient K _AFWOT and leaning retard correction value Δθ
_RDWOT is set to a value of 1.0 and a value of 0, respectively, and the routine ends.

In this case, the air-fuel ratio supplied to the engine 1 is not _leaned by the leaning coefficient K _AFWOT , and the ignition timing is not retarded by the _leaned retard correction value Δθ _RDWOT .

If the determination result of step S10 is affirmative (Yes), that is,
When the engine 1 is operating in the above-described predetermined acceleration operation range, the process proceeds to step S14, and the value 1 is added to the previous value of the engine rotation number N. The engine rotation number N represents the engine rotation number from the time when the engine 1 first enters the predetermined acceleration operation region. Then, in the subsequent steps S16 and S17, the engine speed N
Is compared with the first predetermined value N1 and the second predetermined value N2, and the return coefficient value K _AFWOT and the lean retard correction value Δθ _RDWOT are calculated and set according to the comparison result.

4 (a) and 4 (b) show the engine rotation number N and
The relationship between the leaning coefficient value K _AFWOT and the leaning retard correction value Δθ _RDWOT set by this is shown. Immediately after the engine 1 enters the predetermined acceleration operation range (at this time, the engine speed N value is a value 1), step S1
6 and S17 are both negative, go to step S18,
Leaning coefficient value K _AFWOT and leaning retard correction value Δ
θ _RDWOT is _calculated by the following equations (3) and (4).

K _AFWOT = α + α1 · N (3) Δθ _RDWOT = β + β1 · N (4) where α is a predetermined value smaller than 1.0 (eg 0.8)
The leaning coefficient value K _AFWOT set only by the predetermined value α is applied to the above equation (1) to calculate the valve opening time T _OUT, and the air-fuel ratio obtained by this calculated value is the predetermined value. A value suitable for obtaining maximum output in the acceleration operation range (for example, 12
~ 13). α1 is a constant and is a coefficient value K _AFWOT from when the engine speed N reaches the value 1 to the first predetermined value N1.
Defines the rate of change (gradient) of. β is a predetermined correction value that gives an optimum ignition timing to this air-fuel ratio, corresponding to the air-fuel ratio obtained by applying the leaning coefficient value K _AFWOT set only by the predetermined value α. β1 is a constant and _defines the changing speed (gradient) of the lean retard correction value Δθ _RDWOT from when the engine speed N reaches the first predetermined value N1 from the value 1.

Until the engine speed N reaches the first predetermined value N1,
The determination results of steps S16 and S17 are both negative, so that step S18 described above is executed and the leaning coefficient value K _AFWOT
Also, the lean retard correction value Δθ _RDWOT is calculated by the above equations (3) and (4).

Next, when the engine speed N is equal to or greater than the first predetermined value N1 and smaller than the second predetermined value N2, the determination result of step S16 is negative, the determination result of step S17 is affirmative, and the electronic control unit 10 executes step S19. Execute and lean coefficient value K
_{The AFWOT} and the lean retard correction value Δθ _RDWOT are calculated by the following equations (5) and (6).

K _AFWOT = α + α1 · N1 + α2 (N-N1) (5) Δθ _RDWOT = β + β1 · N1 + β2 (N-N1) (6) where α2 and β2 are constants set to values smaller than the above α1 and β1, respectively. Is. Therefore, step S19
The leaning coefficient value K _AFWOT and the leaning retard correction value Δθ _RDWOT calculated in step 2 are different from those calculated during the period in which the engine speed N reaches the value 1 from the first predetermined value N1. ) Is small.

When the number of engine revolutions N reaches the second predetermined value N2, the step S12 is executed, and the lean coefficient value K _AFWOT and the lean retard correction value Δθ _RDWOT are set to 1.0 and 0, respectively. It is set (see FIG. 4).

In this way, the leaning coefficient value K _AFWOT is set to a value smaller than 1.0 until the engine speed N reaches the second predetermined value N2. By multiplying the basic valve opening time T _B by the correction coefficient K _AFWOT , the fuel injection amount is reduced and corrected to the lean side, and unless the acceleration operation is continued for a long time, the mixture supplied to the engine 1 is mixed. The air-fuel ratio of air will be set to a suitable value depending on the output characteristics during acceleration.

Further, the leaning coefficient value K _AFWOT and the leaning retard correction value Δθ _RDWOT control the tailing amount of these values according to the engine speed N, and therefore the tailing is fast at high speed operation and slow at slow speed operation. The durability of the engine 1 can be ensured over the entire operating range from high speed to low speed.

The first and second predetermined values N1 and N2, constant values α1 and α2,
Both β1 and β2 are set in consideration of the allowable heat resistance temperature of the exhaust system, and may be set to appropriate values for each engine. _Further , the gradual increase ratios of the leaning coefficient value K _AFWOT and the lean retarding correction value Δθ _RDWOT are not limited to those in the embodiment shown in FIG. 4, and the gradual increase curve has three folds. Various modifications are conceivable.

Further, in the above-mentioned embodiment, the basic valve opening time T _B and the basic ignition timing θ _B are explained as an example in which they are calculated and set according to the engine speed Ne and the intake negative pressure Pb. It may be set according to the engine load such as the amount and the opening degree of the slot valve.

(Effects of the Invention) As described above in detail, according to the fuel supply amount control method for accelerating the internal combustion engine of the present invention, the internal combustion engine is operated in the predetermined acceleration operation range in which the exhaust gas temperature should be regulated. At this time, the fuel amount is set according to the engine speed and the magnitude of the load so that the air-fuel ratio of the air-fuel mixture to be supplied to the engine is on the fuel rich side of the theoretical air-fuel ratio, and the set fuel amount is set to the set fuel amount. When controlling the amount of fuel supplied to the internal combustion engine based on the engine, when it is detected that the internal combustion engine has rushed into the predetermined acceleration operation range, from the time when the rush is detected until the predetermined period ends, the engine is In the fuel supply amount control method at the time of acceleration of the internal combustion engine that corrects the air-fuel ratio to the lean fuel side by correcting the amount of fuel set according to the rotation speed and the magnitude of the load, the entry into the acceleration region is performed. When detected To the end of the predetermined period, the amount of fuel reduced and corrected at the start of the predetermined period is set according to the engine speed and the load at the end of the predetermined period. And a step of setting the fuel amount to be changed according to the elapsed time of the detected period when returning to the specified fuel amount. Since it is set to be larger than the rate of change of the fuel amount in the vicinity of the end point, and preferably, the ignition timing is retarded according to the passage of the detected period, so that the exhaust valve, the exhaust manifold, etc. are accelerated when the internal combustion engine is accelerated. High output can be obtained without adversely affecting the heat, and fuel consumption characteristics and exhaust gas characteristics can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the overall configuration of an engine control device for carrying out the method of the present invention, and FIG. 2 is an acceleration lean coefficient calculation executed by an electronic control device 10 shown in FIG. FIG. 3 is a flowchart showing a routine, FIG. 3 is a graph showing a predetermined acceleration operation region in which the exhaust gas temperature should be regulated, and FIG.
Of the lean system coefficient value K _AFWOT and the retard correction value Δθ _RDWOT at the time of leaning, which changes with the increase of the engine, and FIG. 5 shows the basic valve opening time T _OUT read according to the engine speed Ne and the intake negative pressure Pb. FIG. 1 ... Engine, 5 ... Throttle valve, 9 ... Spark plug,
10 ... Electronic control unit, 20 ... Fuel injection valve, 24 ... Negative pressure sensor, 28 ... Crank angle sensor.

Claims (2)

(57) [Claims] 1. When an internal combustion engine is operated in a predetermined acceleration operation range in which the exhaust gas temperature is to be regulated, the air-fuel ratio of the air-fuel mixture to be supplied to the engine is set to be on the fuel rich side of the theoretical air-fuel ratio. When the fuel amount is set according to the engine speed and the magnitude of the load and the fuel amount supplied to the internal combustion engine is controlled based on the set fuel amount, the internal combustion engine operates in the predetermined acceleration operation range. When it is detected that the air fuel ratio has been detected, the fuel amount set according to the engine speed and the magnitude of the load is reduced and corrected from the time when the rush is detected until the predetermined period ends. In the fuel supply amount control method for accelerating an internal combustion engine for correcting the fuel lean side, a procedure for detecting a lapse of a period from the time when the entry into the acceleration region is detected until the predetermined period ends, and the predetermined period The amount of fuel to be reduced at the beginning of the period is returned to the amount of fuel set according to the engine speed and the magnitude of the load at the end of the predetermined period. The internal combustion engine is characterized in that the change rate of the fuel amount in the vicinity of the start time point of the predetermined period is set to be greater than the change rate of the fuel amount in the vicinity of the end time point of the predetermined period. Fuel supply amount control method during engine acceleration. 2. The method for controlling the fuel supply amount during acceleration of an internal combustion engine according to claim 1, wherein the ignition timing is retarded according to the passage of the detected period.