JPS60164639A - Drive system for fuel injection valve - Google Patents

Abstract

PURPOSE:To precisely control the air-fuel ratio always irrespective of variations in the frequency of an injection valve drive signal, by giving a compensation in consideration with the frequency characteristic of a fuel injection valve to a pulse by which the fuel injection valve gives a basic air-fuel ratio to the engine. CONSTITUTION:When a computer 24 computes a basic pulse TP, a TP compensation map 2 is searched in accordance with an engine rotational speed Ne to calculate a compensating coefficient (k). At this time the map 32 is divided into nXn, and a compensating coefficient (kij) in accordance with the vairation ranges of the rotational speed Ne and the pulse width TP is stored in each divided map section. The larger (i) and (j), the less the value of (kij) would be. Further, the pulse width of a drive signal fed to an injector is given by an equation: Ti=k.K.TP, and the compensating coefficient (k) takes a value necessary for compensating the frequency characteristic of the injector. With this arrangement, by removing various compensating date K such as for example, an engine temperature, etc., the fuel injection amount Qf has no relation to the rotational speed Ne and the pulse width TP so that the air-fuel ratio may be given always, corresponding to the control of TP.

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 the invention relates to the control of a fuel injection valve in a fuel injection type internal combustion engine, and the amount of fuel injected per unit valve opening operation is controlled by 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, in order to meet strict exhaust gas regulations and maintain high performance, electronically controlled fuel injection type air-fuel mixture supply means have been widely adopted, and dynamic fuel injection valves have been used. Fuel, such as gasoline, is injected into the airflow passage to create an air-fuel mixture.

Therefore, an example of such an electromagnetically actuated fuel injection valve is
As shown in the figure.

Incidentally, such a fuel injection system is disclosed in, for example, Japanese Patent Application Laid-Open No. 56-9626, Japanese Patent Application Laid-Open No. 57-243'7, and the like.

This 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 a core, 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 pulp, 12 is a swirl tip, 13 is a return hole, 14 is a coil terminal, 15 is a spring adjuster , 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 8 of the nozzle 9 by a return spring 16.

Now, when a coil #5 K current is supplied from the terminal 14, 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 from the seat surface S. Pull apart by a predetermined distance. Note that the predetermined size at this time is determined by the large diameter portion of the plunger rod 7 coming into contact 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 lO portion as shown by the arrow while being maintained at a pressure of 0.7 Kf/-.

Therefore, the coil 5 is energized as described above.

When the ball valve 11 is pulled away from the seat surface S of the nozzle/L-9, fuel flows into the nozzle 9 through the annular gap formed between the ball valve 11 and the seat surface S. It swirls through a spiral groove formed on the outer periphery of the swirl tip 12 and is ejected downward as shown by the arrow, and mixes with the intake air flow of the engine to form 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 injection amount of fuel per unit time is regulated. The amount of fuel supplied can be controlled by supplying pulsed current to the fuel cell and changing the flow ratio of this pulsed current.

The air-fuel ratio of the air-fuel mixture can be controlled. The spring adjuster 15 functions to adjust the amount of compression of the return spring 16 and the force necessary to separate the ball valve 1it from the seat ms, thereby correcting variations in the valve opening characteristics.

By the way, in a fuel injection type air-fuel mixture supply system using such an electromagnetically actuated fuel injection valve, as mentioned above, it is not possible to open the fuel injection valve in a pulsed manner.
In order to control the amount of fuel supplied, a pulse current is supplied to the coil 5. For example, in the case of an automobile engine, the frequency of the pulse current is approximately 20
The pulse width varies over a range from [Hz:] to 200 (Hx), and in this state, the air-fuel ratio is controlled by further varying the pulse width.

Therefore, the reference E is when the frequency of the pulse current to be supplied to the fuel injector is 100 [Hz], the twisting material supply at that time is Qt, the frequency f is plotted on the horizontal axis, and the fuel is plotted on the vertical axis. An example of the characteristics of the fuel injection valve is shown in FIG. 2 by taking the supply amount deviation ΔQf/QfC%].

Here, the characteristic of the broken line is that the pulse width TI of one pulse current is t
, (:m8), and the solid line characteristic is the pulse width T.
I represents t and (ms), respectively; 1. <
1. This shows the case where .

As is clear from Fig. 2, the fuel injection valve (hereinafter referred to as an injector) shown in Fig. 1 has frequency characteristics in its operation, and as the frequency increases, the pulse width T
The injection amount Qt increases even under +, and the pulse width TIK
It can be seen that it also has the characteristic of increasing depending on the value. Note that Δq1 is the deviation ΔQt/ when pulse width TI = t.
Qt and Δq.

represents ΔQf/Q< when Tt=t.

Fig. 3 shows the relationship between the waveform of the drive current for the injector and the stroke of the ball valve 11, where the solid line shows the characteristics at 100 Hz) and the broken line shows the characteristics at 140 Hz.
(The characteristics are shown when Hz:l, and in each case, the pulse width T+ is kept constant.

As is clear from Fig. 3, the operation of the injector pulp does not completely follow the drive current waveform, and there is a time delay of Δt when the current waveform rises, and Δt when the current waveform falls. It can be seen that this is accompanied by a significant delay in the valve closing operation.This is due to the inductance of the coil 5, the mass of the pulp movable part, and the influence of residual magnetism in the magnetic circuit. As a result, even if the drive current pulse % + T i is kept constant, if the frequency f changes, the average value of the pulp stroke will differ, and the average value when f = 100 [H2] is =
140 (H2:] becomes ■. Then, the fuel injection amount Q
Since f is approximately determined by the average value of this valve stroke,
After all, as shown in FIG. 2, the fuel injection amount Qt is determined by the frequency f
It depends on the pulse width Ti and the pulse width Ti. Note that the dependence on the pulse width T1 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+ increases.

Therefore, in conventional fuel injection systems, when the engine speed changes and the frequency of the drive signal supplied to the injector changes, the accuracy of fuel injection amount control decreases, making it difficult to obtain sufficient air-fuel ratio control characteristics. The drawback was that it was not possible.

[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. An object of the present invention is to provide an injector control method that enables the above-mentioned control.

[Summary of the invention]

To achieve this objective, the present invention provides a method for determining the pulse width of the injector drive signal, which is determined by the intake air amount and rotational speed of the engine, and which is necessary to provide a predetermined air-fuel ratio to the engine at that time. hand.

The special feature is that the correction is provided in consideration of the frequency characteristics of the injector which depend on at least one of the frequency of the drive signal and its pulse width.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Hereinafter, the control method of the fuel injection valve according to the present invention will be explained with reference to the illustrated embodiment.

FIG. 4 shows an embodiment of the present invention, in which the intake air amount detector is shown;
22 is an engine rotation speed detector, 24 is a basic pulse width calculator, 26 is various correction calculation circuits, 28 is various detectors, 3
04-! , output device, 32 is a map, and 34 is a basic pulse width sleeve plus calculation circuit.

The intake air amount detection part is a movable flap type. /) It consists of a wire-type air flow rate sensor, an intake negative pressure sensor, etc., and functions to generate a signal Q8 representing the intake air flow rate of the engine.

The engine rotation speed detector n consists of a crank angle sensor, etc., and provides a signal N representing the rotation speed of the engine.

It functions to generate.

The basic pulse @ authenticator 24 is the basic pulse width Tp of the drive signal to be supplied to the injector based on the signals QII and Ne.
It functions to generate. In addition, this basic nokurusu@Tp
corresponds to the fuel supply required to provide a predetermined air-fuel ratio when the engine is in standard operating conditions.

As shown in FIG. 5, the map 32 stores in advance a correction coefficient k necessary for correcting the frequency characteristics of the injector shown in FIG. 2, corresponding to the data Tp and the rotational speed Ne. , thereby the coefficient k corresponding to the data Tp and Na at that time. ! 1-knn.

The basic pulse width correction calculation circuit A functions to correct the basic pulse width TpK using a correction coefficient k.

Various correction calculation circuits 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 U. It functions to provide correction by.

The detector path consists of various sensors such as a water temperature switch that operates when the engine coolant temperature reaches a predetermined value.
It functions to generate correction data K required by various correction calculation circuit sections.

The output device I supplies a drive signal with a pulse width TI to the electromagnetic coil of the injector at predetermined timings, for example, at timings synchronized with the rotation of the engine, thereby injecting fuel.

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

Next, the operation will be explained.

When the engine rotates, the signal Q is output depending on the state at that time.
II and Ne are generated, and the basic pulse width Tp is calculated from the calculation ROM accordingly. The pulse width Tp at this time may be calculated each time by # calculation, or may be determined by searching a map in which predetermined data is stored in advance.

Once the basic pulse width Tp is equalized in this way, the mag 32 is searched using this and the engine rotational speed Ne, and a correction coefficient is calculated.

As shown in FIG. 5, the map 32 at this time is divided into nXn pieces by a predetermined number n, and the corresponding correction coefficient kB is determined according to the range of change of the engine speed Ne and pulse width Tp. It is stored.

That is, the rotational speed Ne of the engine is divided from the minimum rotational speed N0 to the maximum rotational speed N, and the pulse width Tp is also divided from the minimum pulse width Tpo to Tpn. Regarding the pulse width TpK, the smaller value TpO corresponds to the light load side of the engine, and the larger value Tpn corresponds to full throttle operation 9i11. As explained in Fig. 2, the characteristics of the injector are that as the frequency f of the drive signal increases, the fuel injection amount (injection amount per unit number of valve openings) depends on the frequency f of the drive signal, and the pulse width of the drive signal remains the same. However, the pulse width T[
The thicker the K, the stronger the above tendency appears, so the correction coefficient to be written in the map 32 is +1.
As l becomes larger, the value becomes smaller as "mo" becomes larger.

Therefore, according to this embodiment, the pulse width T1 of the drive signal supplied to the injector is Ti = k·K −'
As mentioned above, the correction coefficient k is the value necessary to correct the frequency characteristics of the injector as shown in Figure 2, so six times the correction for engine temperature, etc. If we consider excluding the data K, the fuel injection 1t, Qf is independent of the frequency f of the drive signal, that is, the engine rotational speed N, and the basic pulse width Tp. It is possible to provide an air-fuel ratio that corresponds to the control of the pulse width Tp, and to perform accurate air-fuel ratio control.

By the way, when the embodiment shown in FIG. 4 is realized by a computer program, the flowchart shown in FIG.

In the embodiment shown in FIG. 6, the correction factor I! is calculated by calculating the pulse width Tp and the engine rotational speed Ne. Although it is preferable to use k, it goes without saying that a map search may be used instead, and a map search can generally be regarded as an ellipse of arithmetic.

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

Fig. 1 is a sectional view showing an example of a fuel injection valve, Fig. 2 is an explanatory drawing showing an example of the characteristics of the fuel injection valve, and Fig. 3 is an explanatory drawing showing an example of the relationship between the drive current waveform and stroke of the fuel injection valve. FIG. 4 is a block diagram showing an embodiment of a control system for a fuel injection valve according to the present invention. FIG. 5 is a conceptual diagram showing one embodiment of a correction map. Figure Wc6 is a flowchart showing the operation of another embodiment of the present invention. Addition: Intake air amount detector, 22: Engine rotation speed detector, 24: Basic pulse width calculator, 26: Various calculation correction circuits , 28...
... Various detectors, 30 ... Output device, 32
...Map, 34...Basic pulse width correction calculation circuit. Figure 1 Fuel out Figure 2 Figure 3 Figure 4 R Figure 5

Claims (1)

[Claims] 1. In an internal combustion engine using an electromagnetically actuated fuel injection valve that controls the amount of fuel injected per unit number of operations using the pulse width of a drive signal, the fuel injection valve controls the basic air flow of the internal combustion engine. A control method for a fuel injector, characterized in that the basic pulse width required to provide a fuel ratio is corrected in consideration of the frequency characteristics of the fuel injector. 2. The fuel injection according to claim 1, wherein the correction is performed by a correction coefficient given as a function of at least one of the rotational speed of the internal combustion engine and the basic pulse width. Valve control method. 3. In claim 2, the correction coefficient is
A control method for a fuel injection valve characterized in that the control method is configured to be given by map search.