JPH0656139B2 - Electromagnetic fuel injection valve - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electromagnetic fuel injection valve used in, for example, an internal combustion engine for automobiles.

[Conventional technology]

A conventionally known electromagnetic fuel injection valve of this type is shown in FIG.
That is, 1 is a valve case, and the case body 2 and the body 3 are integrally connected by bending the ends of the case body 2. A case cover 4 is attached to the body 3 by press fitting. The electromagnetic coil 5 in the case body 2 is connected to the computer (CP
U) 7 gives an electric signal to generate an electromagnetic force. Due to this electromagnetic force, a suction force is generated between the stator 8 and the armature 9, and the armature 9 is returned to the coil spring 10 for return.
It is moved upward in the figure against the pressing force of. A needle valve 11 is integrally connected to the armature 9,
The needle valve 11 is also moved integrally with the armature 9 upward in the drawing.

As shown in FIG. 3, the armature 9 includes an end surface facing the one end surface of the cylindrical stator 8 and the armature 9
And a cylindrical outer peripheral surface extending along the moving direction of the outer peripheral surface, and the outer peripheral surface faces the case body 2.

On the other hand, the fuel pumped from the fuel tank 12 by the electromagnetic pump 13 passes through the filter 14 and is sent to the main fuel injection valve and the pressure control valve 15. The pressure control valve 15 keeps the fuel pressure in the supply passage extending from the electromagnetic pump 13 to the pressure control valve 15 constant, and as a result, the fuel having a constant pressure regulated by the pressure control valve 15 is sent to the fuel injection valve. Has been. The fuel having a constant pressure applied to the present fuel injection valve is passed through the joint portion 16 and the filter 17 to a fuel passage 18 formed inside the stator 8, inside and the outer peripheral portion of the armature 9 and the outer peripheral portion of the needle valve 11. Through to the valve seat portion 19. Normally, the lower end of the needle valve 11 abuts the valve seat portion 19 to close the fuel injection hole 20, but as described above, the armature 9 and the needle valve 11 move upward due to the energizing action when the electromagnetic coil 5 is energized. When moved, the needle valve 11 opens the valve seat portion 19 and causes the fuel in the fuel passage 18 to be ejected from the injection hole 20. When the signal from the computer 7 is stopped, the armature 9 and the needle valve 11 are moved downward and downward by the pressing force of the coil spring 10, the needle valve 11 is seated on the valve seat portion 19 and the injection hole 20 is closed. Therefore, the fuel injection is stopped. A magnetic flow path (hereinafter referred to as “magnetic path”) generated when a current flows through the electromagnetic coil 5 by a signal from the computer 7 is indicated by an arrow in the figure. In this magnetic path, the portion having the smallest transverse cross section in the direction perpendicular to the flow of magnetism is the facing area of the stator 8 and the armature 9.

The above operating characteristics are shown by the solid line in FIG. 4, and have the following characteristics with respect to the elapsed time t. That is, the fourth
In the figure, To is the time required from the moment when a signal is given from the computer 7 until the movable side stopper 21 provided integrally with the needle valve 11 hits the fixed side stopper 22 fixed to the case body 2 (hereinafter referred to as the valve opening operation. And Tc represents the time required from the moment the signal from the computer 7 stops until the needle valve 11 is seated on the valve seat portion 19 (hereinafter referred to as the valve closing operation time).
The time T ₁ during which a signal is applied from the computer 7 to the electromagnetic coil 5 is called a pulse. Here, the current flowing through the electromagnetic coil 5 is shown by a solid line, and shows a response with a substantially constant delay with respect to the pulse t ₁ .

[Problems to be solved by the invention]

Since this type of electromagnetic fuel injection valve shown in FIG. 3 is usually required to operate at high speed, it is designed to obtain a large suction force with a small current. Therefore, when a rectangular voltage pulse is applied to such an electromagnetic fuel injection valve, the needle valve 11 opens with a small magnetic flux, and the magnetic flux rises even after the valve-opening operation time, increasing unnecessary suction force. . Furthermore, since the current flowing through the coil 5 also exhibits a first-order lag response, it takes a long time to reach a constant current and magnetic flux. Subsequently, after the pulse is removed, the high magnetic flux state is demagnetized, so that the valve closing operation time becomes long. or,
If the current and magnetic flux have short pulses as shown in Fig. 4 so that they do not reach a certain value, the values of the current and magnetic flux at the time of pulse removal are different from those when the pulse is long. There is a drawback that the direct relationship of the injection amount with respect to t ₁ is broken. Further, in Japanese Patent Laid-Open No. 57-159955, a structure in which high-speed response is taken into consideration is taken into consideration, but the behavior of the current flowing through the electromagnetic coil is the same as that shown by the solid line in FIG. It cannot be said that the problem of was improved sufficiently.

Further, in the technology of Japanese Utility Model Laid-Open No. 56-162371, the magnetic field is analyzed by the finite element method to increase the speed of the solenoid valve. However, in this technology, in order to effectively pass the magnetic flux, the magnetic flux is directed in the direction of the magnetic flux. Along with the above-mentioned prior art, it is impossible to suppress an excessive rise above the magnetic flux required to move the armature.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 53-10129, a strong suction force is exerted in the initial stage of movement of the valve body, and thereafter the increase of the suction force is suppressed, but this technique can move the direction of the magnetic flux lines. In addition to requiring a complicated shape for the facing surfaces of the fixed iron core and the movable iron core to change according to the amount of movement of the iron core, the problem that an excessive rise in magnetic flux cannot be suppressed as in the above-mentioned conventional technique There was a point.

Further, in the technique of Japanese Patent Laid-Open No. 51-137648, a member that easily causes magnetic saturation is adopted as a member through which a magnetic flux passes in the initial stage of suction to prevent a change in initial suction force due to a change in power supply voltage. However, even if the voltage is low, the effective magnetic flux is reduced and high-speed response cannot be obtained, and the structure is such that the facing area increases after suction, and the excessive increase in magnetic flux cannot be suppressed. there were.

Further, Japanese Utility Model Laid-Open No. 55-135416 discloses a technique of increasing the resistance of a magnetic circuit to reduce the residual magnetic force in order to prevent the recovery time of the electromagnet from being prolonged due to the residual magnetic force. However, this technique reduces the residual magnetic flux density remaining after demagnetizing the operating coil, and does not disclose limiting the total magnetic flux during energization of the operating coil. In particular, as shown in FIG. 3 of the publication, the technology of this publication is characterized in that the BH curve is made to have a gentle slope, and that the magnetoresistance and the magnetomotive force (ampere turn) are increased. However, there is no intention to change the saturation characteristics. Therefore, although it is a technique for increasing the magnetic resistance of the magnetic circuit, there is no disclosure that the magnetic circuit is used in a region where the magnetic flux is saturated, and there is a problem that the magnetic flux excessively rises during energization. Further, in this technique, as a result of the BH curve being gently inclined, it becomes impossible to generate a sufficient magnetic flux when the magnetomotive force is small, and the responsiveness at the start of energization of the electromagnetic coil is impaired.

In view of the above-mentioned problems of the prior art, the present invention can quickly attract the armature even with a magnetomotive force due to a small current when the electromagnetic coil is energized when the stator and the armature are separated from each other, and the electromagnetic coil It is an object of the present invention to provide an electromagnetic fuel injection valve capable of quickly demagnetizing the magnetic flux state upon energization to a residual magnetic flux state upon energization stop and returning the armature at high speed.

[Means for solving problems]

In order to achieve the above object, the present invention relates to an electromagnetic fuel injection valve for adjusting a fuel supply amount to an internal combustion engine by a fuel injection time from an injection hole, including: a stator formed of a magnetic material; and a stator formed around the stator. An electromagnetic coil provided, an end face formed of a magnetic material and movably facing the one end face of the stator, facing the one end face of the stator, and an outer peripheral surface extending in the moving direction. An armature that is attracted and moves in the direction of the stator when the electromagnetic coil is energized, and is made of a magnetic material, passes from the other end of the stator to the outside of the electromagnetic coil, and reaches the outer peripheral surface of the armature. A magnetic path forming member that constitutes a magnetic path; a valve body that is opened and closed by the movement of the armature to intermittently inject fuel from the injection hole; and the armature. And a spring for urging the valve body in a direction away from the stator, and a cross-sectional area orthogonal to the direction of the magnetic flux at the time of energizing the electromagnetic coil in a part of the stator or the armature, the stator and the armature. The magnetic flux is in a non-saturated state when the electromagnetic coil is energized and before the armature is attracted and moved, and when the electromagnetic coil is energized and the armature is energized. The magnetic flux is saturated immediately after the suction movement of
And a magnetic diaphragm that restricts an increase in magnetic flux when the valve body is in a valve open state. Technical means called an electromagnetic fuel injection valve is adopted.

[Action]

 The operation of the above-described configuration of the present invention will be described.

A magnetic flux is generated when the electromagnetic coil is energized. This magnetic flux passes through the magnetic path, and among the members that make up this magnetic path,
A magnetic diaphragm is formed in a part of the stator or the armature facing each other through the facing surface. Especially the magnetic diaphragm
The cross-sectional area in the direction orthogonal to the magnetic flux generated when the electromagnetic coil is energized is smaller than the facing surface area between the stator and the armature.

Here, the magnetic circuit at the start of energization can be regarded as a magnetic circuit having an air gap on the opposing surface of the stator and the armature, and most of the magnetomotive force of the electromagnetic coil is consumed because the magnetic flux passes through this air gap. To be done. However, since the magnetic resistance of the air gap decreases as the facing area increases, a large magnetic flux can be generated with a small magnetomotive force by increasing the facing area. In the present invention, since the cross-sectional area of the magnetic diaphragm is smaller than the facing area of the stator and the armature, that is, the magnetic diaphragm is formed with the facing area secured, a small current generated at a small current in the initial stage of energization of the electromagnetic coil is generated. Even with a magnetic force, a large magnetic flux can be generated, and the armature is attracted at high speed against the biasing force of the spring. As a result, the valve element connected to the armature opens, and fuel is injected from the injection hole.

Then, by energizing the electromagnetic coil, the armature is attracted and the current gradually increases and the magnetic flux rises. Here, the stator and the armature made of a magnetic material have magnetic flux saturation characteristics, and even if the magnetomotive force continues to increase, the magnetic flux is limited by the saturation magnetic flux density. Therefore, the magnetic diaphragm having a small cross-sectional area and in which the magnetic flux is concentrated is in a saturated magnetic flux state and suppresses the rise of the total magnetic flux passing through the magnetic circuit.

Furthermore, when the energization of the electromagnetic coil is stopped, the magnetomotive force disappears and the magnetic flux drops sharply. Here, the magnetic flux of the magnetic material is reduced only to the residual magnetic flux even if the magnetomotive force is completely disappeared, but since the total magnetic flux during energization is limited in the present invention, the residual magnetic flux is rapidly reduced, The armature is returned at high speed by the biasing force of the spring. As a result, the valve body is closed and fuel injection from the injection hole is stopped.

〔Example〕

 The first embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a part of the stator 8 is provided with a cross-sectional area portion smaller than the opposing area of the stator 8 and the armature 9, and a magnetic diaphragm 23. This cross-sectional area is needle valve 1
It is set so that there is no resistance to magnetism up to the magnetic flux required for the valve opening operation of No. 1 and the saturation magnetic flux density of the stator 8 is reached for the magnetic flux flowing immediately after the valve opening operation is completed. The other structure is the same as that of the electromagnetic fuel injection valve shown in FIG.

According to the above configuration, as shown in FIG. 4, the electromagnetic coil 5 is energized in response to the rise of the signal from the computer 7. The behavior of the current flowing through the electromagnetic coil 5 at this time is similar to the conventional behavior due to the counter electromotive force due to the inductance component of the electromagnetic coil 5 at the valve opening operation time To as shown by the broken line, but immediately after the valve opening operation is completed. Since the stator 8 is brought into the saturated magnetic flux density state by the magnetic diaphragm 23 and the rise of the magnetic flux is eliminated, the inductance component of the electromagnetic coil 5 becomes zero and the value immediately settles to a predetermined value determined by the internal resistance of the electromagnetic coil 5. This eliminates the unnecessary increase in the suction force that accompanies the increase in the magnetic flux after the valve opening operation that is seen in the conventional injection valve. In the valve closing operation, the valve closing operation time Tc is determined by the time until the demagnetization from the magnetic flux state determined by the magnetic diaphragm 23. Therefore, the valve closing operation time Tc becomes short, and the high speed valve is operated. Operation will be obtained. Since the magnetic flux density of the stator 8 is saturated immediately after the opening operation is completed, regardless of the length of the pulse t _1, the closing operation time Tc becomes constant value, the linear relationship between the injection quantity with respect to the pulse t ₁ is short It can be sufficiently secured even in the pulse.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, a hollow portion 91 is provided inside the armature 9, and a portion of the magnetic path of the armature 9 has a cross-sectional area smaller than the facing area between the stator 8 and the armature 9, that is, the magnetic diaphragm 23 by the hollow portion 91. It has become. This cross-sectional area has the same conditions as the magnetic diaphragm 23 provided in the stator 8 of the first embodiment. Further, the cross-sectional areas of the cavity 91 and the magnetic diaphragm 23 are determined in consideration of the strength and durability of the armature 9 itself and the connecting portion of the armature 9 and the needle valve 11 with respect to the fluctuation of the armature 9.

In the above construction, the electromagnetic coil 5 is energized in response to a signal from the computer 7 as in the first embodiment, and a current flows as shown by the broken line in FIG. 4, but immediately after the valve opening operation is completed, the armature is closed. 9 becomes a saturated magnetic flux density state by the magnetic diaphragm 23, and the rise of the magnetic flux disappears.
The inductance component of the electromagnetic coil 5 becomes zero and the current settles at a predetermined value determined by the internal resistance of the electromagnetic coil 5. Therefore, as in the first embodiment, unnecessary suction force is eliminated. Further, the valve closing operation time Tc is also shortened, high-speed response is obtained, and even with a short pulse, the linear relationship between the pulse t ₁ and the injection amount is sufficiently secured.

Therefore, in each of the above-described embodiments, the armature 9 moves in response to the pulse from the computer 7, and the needle valve 11 moves.
Accordingly, the valve seat portion 19 is seated on and off, and a desired amount of fuel is injected from the fuel injection hole 20.

〔The invention's effect〕

According to the electromagnetic fuel injection valve of the present invention described above, since the stator or the armature is formed with the magnetic throttle having the cross-sectional area smaller than the facing area of the stator and the armature, the facing area of the stator and the armature is ensured. At the start of energization of the coil, a large amount of magnetic flux can be passed even with a small amount of current, and the armature can be moved at high speed. Since it is suppressed, demagnetization is promptly performed after the energization of the electromagnetic coil is stopped, and the armature can be returned and moved at high speed.
Therefore, according to the present invention, it is possible to provide an electromagnetic fuel injection valve having a high-speed responsiveness to intermittent energization of an electromagnetic coil.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a first embodiment of the present invention, and FIG.
FIG. 4 is a partial sectional view showing a second embodiment of the present invention, FIG. 3 is a partial sectional view showing a conventional electromagnetic fuel injection valve, and FIG. 4 is a signal time showing an operating state of the conventional and the present invention. It is a chart. 1 ... Valve case, 2 ... Case body, 5 ... Electromagnetic coil, 8 ... Stator, 9 ... Armature, 11 ... Needle valve, 20 ... Fuel injection hole, 23 ... Magnetic throttle.

Claims (3)

[Claims] 1. An electromagnetic fuel injection valve for adjusting the amount of fuel supplied to an internal combustion engine according to a fuel injection time from an injection hole, a stator made of a magnetic material, and an electromagnetic coil provided around the stator. A magnetic material is provided so as to be movable opposite to one end surface of the stator, and has an end surface facing the one end surface of the stator and an outer peripheral surface extending in the moving direction. An armature that is attracted and moves in the direction of the stator when energized, and a magnetic path that is formed of a magnetic material and that passes through the outside of the electromagnetic coil from the other end side of the stator to the outer peripheral surface of the armature. A path forming member, a valve body that is opened and closed by movement of the armature, and connects and disconnects fuel injection from the injection hole; and the armature and the valve body. A spring urging in a direction away from the theta and a part of the stator or the armature that has a cross-sectional area orthogonal to the direction of the magnetic flux when the electromagnetic coil is energized is smaller than the facing area of the stator and the armature. The magnetic flux is in a non-saturated state when the armature is attracted and moved when the electromagnetic coil is energized, and immediately after the armature is attracted and moved when the electromagnetic coil is energized. The magnetic flux is saturated,
An electromagnetic fuel injection valve, comprising: a magnetic throttle that limits an increase in magnetic flux when the valve body is open. 2. The electromagnetic fuel injection valve according to claim 1, wherein the magnetic throttle is formed in the stator. 3. The electromagnetic fuel injection valve according to claim 1, wherein the magnetic throttle is formed in the armature.