JPH08326620A - Electromagnetic fuel injection valve for internal combustion engine - Google Patents

Abstract

PURPOSE: To reduce opening delay and closing delay by arranging a plurality of coils which compose a magnetic circuit, thereby carrying current to a plurality of coils at the opening operation for enlarging magnetic attraction force, and reducing attraction force in an opened state. CONSTITUTION: Two coils 30, 31 are wound, while each one side is connected to form a tap part 33 and connected to a power source 32, and the other side ends are arranged through driving circuits 36, 37. The driving circuits 36, 37 are switched ON or OFF based on a signal from a CPU 38, for controlling current carrying to the coils 30, 31. Current is carried to both the coils 30 and 31 for a specified time from starting the current carrying. Strong magnetic flux is generated and speedy opening operation is performed, for reducing opening delay. After a specified time passed, current carrying to one coil 30 is stopped, keeping the current carrying only to the other coil 31. In such a state, the current carrying to the coil 31 is also stopped. Since magnetic attraction force is small originally, speedy closing operation is enabled for reducing closing delay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic fuel injection valve for internal combustion engines.

[0002]

2. Description of the Related Art FIG. 1 shows a structural example of a conventional electromagnetic fuel injection valve for an internal combustion engine. The operation of the injection valve will be described with reference to this figure. The injection valve is provided with one coil 1 for exciting a magnetic circuit, and a pulse supplied from the terminal 10 is supplied to the coil 1 to generate a magnetic flux in the magnetic circuit including the core 6, the yoke 7 and the plunger 8 to generate a magnetic flux. A suction force is generated to overcome the force of the spring 3 for urging the plunger 8 toward the seat portion 4 to move it toward the core 6 and lift the valve body 2 connected to the plunger 8 from the seat portion 4. Then, the pressurized fuel supplied to the injection valve is injected from the gap of the seat portion 4 into the intake pipe through the orifice 5. The stroke range of the plunger 8 is the seat portion 4
It is regulated by the stopper 9. Both ends of the coil 1 are connected by two terminals 10 which are terminals 10-1 and 10-2.

[0003]

However, in such a fuel injection valve, due to the magnetic inductance of the magnetic circuit, the current and magnetic flux do not rise immediately even when the coil is energized, and the coil actually opens. A delay time is required until the operation starts and ends. On the other hand, when the energization is stopped, the magnetic flux does not disappear immediately, so the magnetic attraction force weakens and a delay time is required until the valve body returns to the valve closing position. These opening and closing delay times result in the cause of impairing the linearity of the injection amount characteristic with respect to the drive signal pulse width applied to the coil.

FIG. 2 shows the factors that impede the linearity of the injection amount.
Will be explained. 2A is a graph 20 showing the relationship between the pulse width and the fuel injection amount when the solenoid valve is driven with a pulse having a period of 10 ms, and FIG. 2B is a pulse width shown at 26. A diagram showing the movement of the valve body 2 when it is input is shown by a thick line 21, and movements of the valve body when driven by other pulse widths are shown by thin lines 23, 24, 35 and the like.

First, the obstruction of linearity due to the valve opening delay when the pulse width is small will be described. When the pulse width is small, the valve body does not move even if a pulse is applied, and therefore there are regions T1 and 22 where fuel is not injected. Next, if the pulse disc is turned off before hitting the stopper, the residual magnetic flux and the velocity of the disc in the valve opening direction will cause the disc to return more slowly than the normal closing operation. There are regions T2 and 23 where the injection amount increases. Further, the valve body 2 bounces after hitting the stopper, but when the pulse has a velocity in the valve closing direction due to the bounce, the pulse is turned off,
Since the valve body returns faster than the normal valve closing operation, there are regions T3 and 24 where the injection amount decreases.

Next, the obstruction of linearity due to the valve closing delay when the pulse width is large will be described. When the pulse width is large, the magnetic flux does not disappear immediately after the pulse is cut.Therefore, there is a delay time before the valve closing operation starts due to the weak magnetic attraction force. When the next pulse is input therein, there is a region T4, 25 in which the injection amount increases because the opening operation is performed before the valve body is closed.

That is, opening delay To, 27 closing delay T
The injection amount linearity can be improved by making c and 28 as small as possible. However, if the magnetic attraction force is increased or the spring force is decreased in order to reduce the opening delay 27, the closing delay 28 increases, and it is difficult to reduce both the opening and closing delays.

[0008]

The above problem can be solved by providing a plurality of coils and energizing more coils during the opening operation than during holding the open state.

[0009]

[Function] By providing a plurality of coils and energizing more coils during the opening operation than when maintaining the opened state, the magnetic attraction force for opening is increased, the opening delay is shortened, and the opened holding state is maintained. Then, by reducing the suction force, the closing delay time can be shortened.

[0010]

FIG. 3 shows a coil wiring diagram of an injection valve according to an embodiment of the present invention. The basic structure of the injection valve of this embodiment is
It is the same as the conventional injection valve shown in FIG. In this embodiment,
The coil 30 and the coil 31 are wound, and the tap portion 33 having one end coupled to each other is connected to the power source 32, and the other ends 34 and 35 of the respective coils are grounded via the drive circuits 36 and 37. The drive circuits 36 and 37 perform on / off operation in response to a signal from the CPU 38, and control the energization of the coils 30 and 31.

FIG. 4 shows the operation of the valve body in the case of this embodiment,
The comparison of the conventional example is shown. First, during the opening operation, both the coil 30 and the coil 31 are energized for a certain period from the start of energization,
By generating a strong magnetic flux, a quick opening operation is performed, and the opening delay To is shortened. After a certain period of time, the coil 30 is deenergized and only the coil 31 is energized.
The magnetic attraction force by the coil 31 at this time is the minimum force required to hold the valve body in the open state.

In this state, if the energization of the coil 31 is stopped in order to perform the closing operation, the magnetic attraction force is originally small, so that the quick closing operation is possible and the closing delay Tc can be shortened. .

According to the present embodiment, the opening operation rises faster and the opening speed increases, so that the linearity in the small pulse width region can be improved. Regarding the bounce after colliding with the stopper, although the collision speed increases, it quickly converges because the suction force in the core direction is large. During the closing operation, the magnetic attraction force is small, so the closing operation starts immediately when the power supply is stopped. This improves non-linearity when driven by pulses that are large in pulse width and close in time.

Further, according to the present embodiment, a large amount of current is passed only when the valve is opened, and the current can be reduced while the opened state is maintained. Therefore, heat generation of the injection valve can be suppressed.

Further, in a system where the fuel pressure is relatively high,
Even if a strong suction force is required for opening, it can be handled by adjusting the number of turns of the coil used for opening.

Further, even if the coil of the injection valve is broken or the drive circuit is broken, since one injection valve has a plurality of coils, the remaining coils are energized,
The operation at the time of failure can be enabled.

[0017]

According to the present invention, with a simple structure, it is possible to shorten the opening / closing valve delay of the electromagnetic fuel injection valve, improve the responsiveness, and improve the linearity of the pulse width and the injection amount.

Further, according to the present invention, the current is increased only when the opening operation is performed, and the current is decreased when the opening state is maintained, so that the heat generation of the injection valve can be suppressed.

Further, according to the present invention, even if a coil disconnection of the injection valve, a drive circuit failure or the like occurs, the remaining coil is energized so that the engine can be operated even in the event of a failure.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional embodiment and an electromagnetic fuel injection valve of the present invention.

FIG. 2 is an explanatory view showing linearity of injection amount and operation of a valve body.

FIG. 3 is a circuit diagram showing an embodiment of the present invention.

FIG. 4 is an explanatory view showing the operation of the valve body according to the embodiment of the present invention.

[Explanation of symbols]

30, 31 ... Coil, 36, 37 ... Drive circuit, 38 ... C
PU.

Claims (3)

[Claims] 1. An electromagnetic fuel injection valve for supplying fuel to an internal combustion engine, comprising a plurality of coils forming a magnetic circuit. 2. The electromagnetic fuel injection valve according to claim 1, wherein in the initial stage of the opening operation of the valve element, a current is applied to a larger number of the coils than when the open state is maintained. 3. A means for detecting a disconnection of the coil of the injection valve or a failure of a drive circuit, and when the occurrence of the failure is detected, the control state of the coil and the drive circuit which have not failed is different from the normal state. The control device for an internal combustion engine according to claim 1.