JPH0372827B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to the control of a fuel injection valve in a fuel injection type internal combustion engine, and in particular to controlling the fuel injection amount per unit valve opening operation using only the pulse width of a drive signal. The present invention relates to a control method for an electromagnetically actuated fuel injection valve.

[Background of the invention]

Conventionally, carburetors have been widely used as an air-fuel mixture supply means for gasoline engines and the like.

However, in recent years, it has cleared strict exhaust gas regulations,
Moreover, in order to maintain high performance, electronically controlled fuel injection type air-fuel mixture supply means has come to be widely adopted.

This type of air-fuel mixture supply means uses an electromagnetically actuated fuel injection valve, which injects fuel such as gasoline into the intake air flow path to obtain an air-fuel mixture.

An example of such an electromagnetically actuated fuel injection valve is shown in FIG.

Furthermore, this kind of fuel injection system is
For example, it is disclosed in JP-A-56-9626 and JP-A-57-2437.

Figure 1 shows an example of an electromagnetically actuated fuel injection valve using a ball as a valve body. In the figure, 1 represents the entire fuel injection valve, 2 is the core, and 3
is a yoke, 4 is a bobbin, 5 is a coil, 6 is a plunger, 7 is a plunger rod, 8 is a stopper, 9
is a nozzle, 10 is a filter, 11 is a ball valve, 12 is a swirl tip, 13 is a return hole,
14 is a coil terminal, 15 is a spring adjuster, and 16 is a return spring.

The ball valve 10 is attached to the tip of the plunger rod 7 by welding or the like, and is normally pressed against the valve seat surface S of the nozzle 9 by a return spring 16.

Now, when current is supplied from the terminal 14 to the coil 5, the core 2 is magnetized and attracts the plunger 6, and the plunger rod 7 is pulled up against the tension of the return spring 16, and the ball valve 10 is moved a predetermined distance from the seat surface S. Just pull away. The predetermined size at this time is determined by the contact of the large diameter portion of the plunger rod 7 with the stopper 8.

Fuels such as gasoline are kept at a constant pressure by pressurizing means such as pumps and pressure adjusting means (not shown).
For example, it is supplied to the filter 10 as shown by the arrow while being maintained at a pressure of 0.7 kg/cm ² .

Therefore, as mentioned above, the coil 5 is energized,
When the ball valve 11 is separated from the seat surface S of the nozzle 9, the ball valve 11 and the seat surface S
The fuel flows into the nozzle 9 through the annular gap formed between the swirl tip 12, and is spouted downward as shown by the arrow while swirling through the spiral groove formed on the outer periphery of the swirl tip 12. It mixes into the engine's intake airflow and forms an air-fuel mixture.

At this time, the fuel is measured by the annular gap formed between the ball valve 11 and the seat surface S, and the amount of fuel injected per unit time is regulated. By supplying a pulse current to the fuel pump 5 and changing the flow ratio of this pulse current, the amount of fuel supplied can be controlled, and the air-fuel ratio of the air-fuel mixture can be controlled.
In addition, the spring adjuster 15 adjusts the amount of compression of the return spring 16, and the ball valve 11
It functions to correct for variations in valve opening characteristics by adjusting the force required to separate the valve from the seat surface S.

By the way, in a fuel injection type mixture supply system using such an electromagnetically actuated fuel injection valve, as mentioned above, the fuel supply amount is controlled by opening the fuel injection valve in a pulsed manner. For this reason, a pulse current is supplied to the coil 5, but the frequency of the pulse current at this time varies over a range of about 20 [Hz] to 200 [Hz] in the case of an automobile engine, for example. However, under this condition, the air-fuel ratio is controlled by further changing the pulse width.

Therefore, the frequency f of the pulse current to be supplied to the fuel injection valve is set as a reference when the frequency is 100 [Hz], the fuel supply amount at that time is Q _f , and the frequency f is plotted on the horizontal axis.
FIG. 2 shows an example of the characteristics of the fuel injection valve, with the deviation ΔQ _f /Q _f [%] of the fuel supply amount plotted on the vertical axis. Here, the characteristics of the magnetic wire are shown when the pulse width T _i of the pulse current is t ₁ [mS], and the characteristics of the solid line are shown when the pulse width T _i is t ₂ [mS], and t ₁ <t ₂ is shown.

As is clear from this Fig. 2, a fuel injection valve (hereinafter referred to as an injector) as shown in Fig. 1
has a frequency characteristic in its operation, and as the frequency increases, the injection amount Q _f increases even under the same pulse width T _i , and also has the characteristic that it increases depending on the pulse width T _i I understand. Note that Δq ₁ is the pulse width
represents the deviation ΔQ _f /Q _f when T _i = t ₁ , and Δq ₂ is T _i
ΔQ _f /Q _f when = t ₂ .

Figure 3 shows the relationship between the waveform of the drive current for the injector and the stroke of the ball valve 11. The solid line represents the characteristics at 100 [Hz], and the broken line represents the characteristics at 140 [Hz]. In all cases, the pulse width T _i is kept constant.

As is clear from Figure 3, the operation of the injector valve does not completely follow the drive current waveform, and there is a time delay of Δt ₁ when the current waveform rises, and Δt ₂ when it falls. , and it can be seen that there is a significant delay in the valve closing operation. This is due to the inductance of the coil 5, the mass of the valve's moving parts, and the influence of residual magnetism in the magnetic circuit.As a result, even if the pulse width T _i of the drive current is kept constant, its frequency f The average value of the valve stroke that changes will be different, and the average value when f = 100 [Hz] is f = 140
[Hz] becomes. And since the fuel injection amount Q _f is almost determined by the average value of this valve stroke,
After all, as shown in FIG. 2, the fuel injection amount Q _f depends on the frequency f and the pulse width T _i . Note that the dependence on the pulse width T _i appears because the operation at the falling edge of the valve stroke due to the residual magnetism described above causes interference between each pulse as the pulse width T _i becomes larger.

Therefore, in conventional fuel injection systems,
When the rotational speed of the engine changes and the frequency of the drive signal supplied to the injector changes, the accuracy of fuel injection amount control decreases, resulting in a drawback that sufficient air-fuel ratio control characteristics cannot be obtained.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and even if the frequency of the drive signal to the injector changes, the fuel injection amount relative to the pulse width of the drive signal is always kept constant, and the air-fuel ratio can be controlled accurately at all times. The object of the present invention is to provide an injector control method that enables the above-mentioned injector control.

[Summary of the invention]

In order to achieve this object, the present invention provides basic pulse width calculation means for calculating a basic pulse width corresponding to the amount of fuel supplied necessary to obtain the basic air-fuel ratio of the engine, and A correction map that uses both as search inputs and outputs correction coefficients necessary for correcting both the fuel injection amount characteristics relative to the driving pulse signal frequency of the electromagnetically actuated fuel injector and the fuel injection amount characteristics relative to the driving pulse signal pulse width. and a pulse width correction means for correcting the basic pulse width data using the correction coefficient to determine the pulse width of the pulse signal, and based on the pulse signal whose pulse width has been corrected by the pulse width correction means. It is characterized by driving an electromagnetically actuated fuel injection valve.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection valve control system according to the present invention will be explained in detail below using illustrated embodiments.

FIG. 4 shows an embodiment of the present invention, in which 20 is an intake air amount detector, 22 is an engine rotation speed detector, 24 is a basic pulse width calculator, 26 is various correction calculation circuits,
28 is various detectors, 30 is an output device, 32 is a map, and 34 is a basic pulse width correction calculation circuit.

The intake air amount detector 20 is composed of a movable flap type, hot wire type, etc. air flow rate sensor, or an intake negative pressure sensor, and functions to generate a signal Q _a representing the intake air flow rate of the engine.

The engine rotation speed detector 22 consists of a crank angle sensor, etc., and is a signal indicating the rotation speed of the engine.
It functions to generate N _e .

The basic pulse width calculator 24 functions to generate a basic pulse width T _p of the drive signal to be supplied to the injector based on the signals Q _a and N _e . Note that this basic pulse width T _p corresponds to the fuel supply amount required to provide a predetermined air-fuel ratio when the engine is in a standard operating state.

As shown in FIG. 5, the map 32 has data T _p
The correction coefficient k necessary for correcting the frequency characteristics of the injector shown in Fig. 2 is stored in advance in accordance with the rotation speed N _e and the data T _p and N at that time. It functions to give one of the coefficients k _po to k _oo corresponding to _e .

The basic pulse width correction calculation circuit 34 has a basic pulse width
It functions to correct T _p using a correction coefficient k.

Various correction calculation circuits 26 are provided for correction of the fuel supply amount depending on the engine temperature and necessary corrections when the engine is accelerating or decelerating, and further apply a correction coefficient K to the pulse width corrected by the correction calculation circuit 34. It functions to provide correction by.

The detector 28 is comprised of various sensors such as a water temperature switch that operates when the temperature of the engine coolant reaches a predetermined value, and functions to generate correction data K required by the various correction calculation circuits 26.

The output device 30 supplies a drive signal with a pulse width T _i to the electromagnetic coil of the injector at predetermined timings, for example, at every timing synchronized with the rotation of the engine,
It functions to inject fuel.

Note that, except for the correction map 32 and the basic pulse width correction circuit 34 using the coefficient k, the configuration of the system shown in FIG. 4 is almost the same as the conventional system.

Next, the operation will be explained.

When the engine rotates, signals Q _a and N _e are generated depending on the state at that time, and the basic pulse width T _p is calculated by the calculator 24 in accordance with these signals. The pulse width T _p at this time may be calculated each time, or may be obtained by searching a map in which predetermined data is stored in advance.

Once the basic pulse width T _p is determined in this way, the map 32 is searched using this and the engine rotational speed N _e to calculate the correction coefficient k.

At this time, the map 32 is divided into n×n pieces by a predetermined number n, as shown in FIG.
Correcting coefficients k _ij corresponding to the change ranges of the engine rotational speed N _e and the pulse width T _p are stored. That is, the engine rotational speed N _e varies from the minimum practical rotational speed N ₀ to the maximum rotational speed N _o , and the pulse width T _p also varies from the minimum pulse width T _p0
Each is divided up to T _po . Regarding the pulse width T _p , the smaller value T _p0 corresponds to the light load side of the engine, and the larger value T _p0 corresponds to the full throttle operation side. As explained in Fig. 2, the characteristics of the injector are such that the higher the frequency f of the drive signal, the higher the fuel injection amount (injection amount per unit number of valve openings), even if the pulse width of the drive signal is the same. Furthermore, as the pulse width T _p becomes larger, the above tendency becomes more pronounced. Therefore, as the correction coefficient k _ij to be written in the map 32, the larger the i becomes, the more the above-mentioned tendency appears. , and the value becomes smaller as j becomes larger.

Therefore, according to this embodiment, the pulse width T _i of the drive signal supplied to the injector is given by T _i =k・K・T _p , and as described above, the correction coefficient k is As shown in Figure 2, it is a value necessary to correct the frequency characteristics of the injector, so if we exclude various correction data K such as engine temperature, the fuel injection amount Q _f is equal to the frequency f of the drive signal, i.e. Regardless of changes in engine speed N _e or basic pulse width T _p , Q _f = C・T _p. However, C: is a constant determined by the injector, etc., and always provides an air-fuel ratio that corresponds to the control of pulse width T _p . It is possible to perform accurate air-fuel ratio control.

By the way, if the embodiment shown in FIG. 4 is realized by a computer program, the result will be as shown in the flowchart shown in FIG. can.

In the embodiment shown in FIG. 6, the pulse width T _p
The correction coefficient k is calculated by calculating the engine speed N _e
, but it goes without saying that a map search may be used instead, and a map search can generally be regarded as a type of calculation.

In addition, in the above embodiment, the case of an injector using a ball valve as shown in Fig. 1 was explained, but in general, an electromagnetically actuated injector has a frequency as shown in Fig. 2 regardless of the type of valve. It goes without saying that the present invention can be implemented regardless of the valve type of the injector because of the characteristics.

〔Effect of the invention〕

As explained above, according to the present invention, even if the engine speed and load condition change, it is possible to always provide a fuel injection amount that accurately corresponds to the basic pulse width, thereby eliminating the drawbacks of the conventional technology. , it is possible to provide a fuel injection valve control method that allows easy air-fuel ratio control with high accuracy.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of a fuel injection valve, Figure 2 is a sectional view showing an example of a fuel injection valve.
The figure is an explanatory diagram showing an example of the characteristics of a fuel injection valve.
The figure is an explanatory diagram showing an example of the relationship between the drive current waveform and the stroke of the fuel injector, FIG. 4 is a block diagram showing an example of the control method for the fuel injector according to the present invention, and FIG. FIG. 6 is a conceptual diagram showing one embodiment. FIG. 6 is a flowchart showing the operation of another embodiment of the present invention. 20... Intake air amount detector, 22... Engine rotation speed detector, 24... Basic pulse width calculator,
26...Various calculation correction circuits, 28...Various detectors, 30...Output devices, 32...Map, 34...
Basic pulse width correction calculation circuit.

Claims (1)

[Claims] 1. In an internal combustion engine control device comprising an electromagnetically actuated fuel injection valve driven by a pulse signal synchronized with engine rotation, the fuel injection amount per unit operation is controlled by the pulse width of the pulse signal. A basic pulse width calculation means that calculates a basic pulse width corresponding to the amount of fuel supplied necessary to obtain the basic air-fuel ratio of the engine, and a basic pulse width calculation means that uses both the basic pulse width and the engine speed as search inputs, and uses the electromagnetically actuated fuel a correction map means for outputting a correction coefficient necessary for correcting both the fuel injection amount characteristic with respect to the driving pulse signal frequency of the injection valve and the fuel injection amount characteristic with respect to the pulse width of the driving pulse signal; and pulse width correction means for correcting the width data to determine the pulse width of the pulse signal, and driving the electromagnetically actuated fuel injection valve based on the pulse signal whose pulse width has been corrected by the pulse width correction means. A drive control device for a fuel injection valve, characterized in that it is configured as follows.