JP2001020835A - Fuel injection valve and internal combustion engine mounting the valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve which has less bouncing of a valve element without severely controlling size precision of the valve element, a housing, and a guide clearance. SOLUTION: This fuel injection valve comprises a fuel injection nozzle 2; a valve seat 3 disposed in the vicinity of the fuel injection nozzle; a valve element 4 to open and close a fuel passage between the valve seat and the valve element; a spring 12 to generate a force to press the valve element against the valve seat; and a drive meant to drive the valve element, the fuel injection valve being constituted such that an interlocking member 13 different from the valve element is located between the valve element 4 and the spring 12. This constitution absorbs energy of collision between the valve element 4 and the valve seat 3 through displacement of the interlocking member 13 and reduces bouncing of the valve element 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve,
In particular, the present invention relates to a fuel injection valve for controlling a fuel supply amount and an internal combustion engine equipped with the same.

[0002]

2. Description of the Related Art A fuel injection valve includes a fuel injection hole, a valve seat disposed in the vicinity thereof, a valve body slidably supported in an axial direction at a position facing the valve seat, and a spring. Is provided.
The spring generates a force that presses the valve body toward the valve seat.

In a state where the valve seat and the valve body are in contact with each other by the spring force, the fuel passage is closed, so that no fuel is injected from the fuel injection hole. When the valve element slides in the axial direction and moves away from the valve seat by driving means using electromagnetic force or fuel pressure, the fuel passage is opened,
Fuel is injected from the fuel injection holes. As described above, in the fuel injection valve, the fuel supply amount is controlled by switching the position of the valve element.

Here, when switching the position of the valve element,
A collision between the valve seat and the valve body or a collision between the stroke restricting means and the valve body on the opposite side of the valve seat in the axial direction occurs. The behavior of the valve body bouncing during the collision (hereinafter referred to as bouncing) may cause a slight variation in the fuel injection amount, so it is desirable to reduce bouncing.

[0005] As a conventional technique for reducing bouncing, there is Japanese Patent Application Laid-Open No. Hei 8-189439. this is,
By forming a fuel throttle passage in the gap between the valve element and the housing that supports the valve element, and by applying viscous resistance to the valve element, it is possible to reduce the speed at which the valve element collides with the valve seat and reduce bouncing. Is what you do.

[0006]

However, in the above-mentioned prior art, when the size of the gap between the valve body and the housing slightly changes, the viscous resistance force acting on the valve body greatly changes. Therefore, when the processing dimensions of the valve element and the housing vary, or when the central axis of the valve element deviates from the central axis of the housing in the range of the guide gap, a sufficient viscous resistance cannot be obtained. Therefore, in order to obtain a stable bouncing reduction effect, there is a problem that it is necessary to strictly control the dimensional accuracy of the valve element, the housing, the guide gap, and the like.

An object of the present invention is to solve the above-mentioned problem and to obtain a stable bouncing reduction effect without strictly controlling the dimensional accuracy of a valve element, a housing, a guide gap and the like.

[0008]

According to the present invention, an interlocking member separate from the valve element is provided between a valve element constituting the injection valve and a spring for pressing the valve element against a valve seat.
When the valve is driven to open and close by electromagnetic force, the valve remains on the valve seat surface, and the interlocking member to which the spring force directly acts acts to absorb the bouncing action.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the fuel injection valve of the present invention.

[0010] The nozzle 1 is provided with a fuel injection hole 2 and a valve seat 3. The valve element 4 includes a movable iron core 5, a rod 6, and a ball 7.
And supported so as to be slidable in the axial direction of the rod 6. At a position facing the shoulder portion 8 of the rod 6, a stopper 9 as a stroke regulating means is provided. The valve element 4 can slide in a range from a lower end position where the ball 7 contacts the valve seat 3 to an upper end position where the shoulder portion 8 contacts the stopper 9. Even when the valve element 4 is at the upper end position, a gap is provided between the movable iron core 5 and the inner iron core 10. Fuel is supplied to fuel supply port 1
6 and is guided to the fuel injection holes 2.

A spring adjuster 11 is fixed in the inner core 10. The spring 12 is provided in a compressed state with the lower end of the spring adjuster 11 as a fixed end. Between the spring 12 and the valve element 4, there is provided an interlocking member 13 which is a movable member which is independently movable with a predetermined weight and is slidable in the axial direction. The spring force is controlled by the interlocking member 13.
Is transmitted to the valve body 4, and the valve body 4 is pressed against the valve seat 3. In this state, the fuel passage is closed,
No fuel injection from the fuel injection holes 2 is performed.

The interlocking member 13 operates as a bouncing absorbing member for absorbing the bouncing of the valve body.

A coil 15 is provided in a space surrounded by the inner core 10 and the outer core 14. When a current is applied to the coil 15, the inner core 10, the movable core 5, and the outer core 14 constitute a magnetic circuit, the movable core 5 is attracted to the inner core 10 by electromagnetic force, and the valve body 4 moves to the upper end position. In this state, a gap is formed between the valve body 4 and the valve seat 3, so that the fuel passage is opened and fuel is injected from the fuel injection hole 2.

The function of the fuel injection valve is to control the amount of fuel supplied by switching the position of the valve element 4 as described above.

Here, when the position of the valve element 4 is switched, a collision between the valve element 4 and the valve seat 3 and a collision between the valve element 4 and the stopper 9 occur. The bouncing of the valve element 4 at the time of the collision may cause a slight variation in the fuel injection amount, so it is desirable to reduce the bouncing.

Therefore, in the present invention, the spring 12
An interlocking member 13 slidable in the axial direction is provided between the valve elements 4. An example of the mechanism by which the bouncing of the valve element 4 is reduced by the operation of the interlocking member 13 will be described with reference to FIGS.

FIG. 2 shows the process of taking out only the valve seat 3, the valve body 4, the stopper 9, the spring 12, and the interlocking member 13 from the fuel injection valve and shifting from the valve-open holding state to the valve-closed holding state. ) To (e).

(A) In the valve-open holding state, the valve body 4 is held at the upper end position by electromagnetic force.

(B) In the movement of the valve body, the electromagnetic force is cut off,
The valve body 4 and the interlocking member 13 move in the direction of the valve seat 3 by the spring force.

(C) The collision between the valve element 4 and the valve seat 3
Represents the moment of collision.

(D) Immediately after the collision, a state in which the interlocking member 13 jumps upward due to the impact due to the collision is shown. Since the collision energy between the valve body 4 and the valve seat 3 is absorbed by the interlocking member 13 jumping up, bouncing of the valve body 4 is reduced.

(E) In holding the valve closed, the interlocking member 13 returns to the state of contacting the valve body 4 again.

FIG. 3 shows the process of taking out only the valve seat 3, the valve body 4, the stopper 9, the spring 12, and the interlocking member 13 from the fuel injection valve and transitioning from the valve-closed holding state to the valve-opening holding state. ) To (e).

(A) In the valve-closed holding state, the valve body 4 is pressed against the valve seat 3 by a spring force.

(B) In the movement of the valve body, the electromagnetic force acts,
The valve body 4 and the interlocking member 13 move upward.

(C) The valve body-stopper collision represents the moment when the valve body 4 and the stopper 9 collide.

(D) Immediately after the collision, a state in which the interlocking member 13 jumps upward due to inertia is shown. Valve 4 and interlocking member 1
3 is temporarily separated, so that there is no spring force acting in the direction in which the valve element 4 rebounds, so that bouncing is reduced.

(E) In holding the valve open, the interlocking member 13 returns to the state of contacting the valve body 4 again.

The bouncing reduction mechanism shown in FIGS. 2 and 3 is an example, and the bouncing may be reduced by a different mechanism depending on the shape of the spring load, the fuel passage, the magnetic circuit, the stopper, and the like. For example, when the electromagnetic force is cut off from the valve open holding state,
The valve element 4 may collide with the valve seat 3 in a state where the valve element 4 is separated from the interlocking member 13 and there is a slight gap between them. When the valve element 4 attempts to rebound from the valve seat 3, the interlocking member 13 collides with the valve element 4 with a slight delay, so that bouncing may be reduced.

FIG. 4 is a graph showing how bouncing is reduced by the mechanism shown in FIGS. 2 and 3, with time being plotted on the horizontal axis and displacement of the valve element on the vertical axis. In a conventional fuel injection valve having no interlocking member 13, large bouncing of the valve body 4 is observed at the stroke end. On the other hand, in the fuel injection valve of the present invention having the interlocking member 13, the bouncing of the valve body 4 can be reduced or the bouncing can be almost eliminated.

In FIG. 4, the time when the electromagnetic force is cut off and the valve body starts to move from the valve opening position to the valve closing position is called Tp. When a small amount of fuel is to be injected, Tp will be reduced. In the case of the conventional structure, the valve starts to move while the valve is bouncing near the valve opening position.

If the electromagnetic force is cut off when the valve element has a negative speed, a valve displacement waveform as shown in FIG. Before the valve element shuts off the electromagnetic force, the time required to reach the valve closing position is short because the valve element already has a negative speed.

On the other hand, if the electromagnetic force is cut off when the valve body has a positive velocity, a valve displacement waveform as shown in FIG. It takes a long time to reach the valve closing position by the time required to reverse the speed of the valve element from positive to negative.

The bouncing does not always occur in the same way, but the period and the amplitude change. Therefore, even if the electromagnetic force is cut off at the same time, the speed of the valve body at that time differs for each operation. As a result, there is a possibility that the valve closing time varies, and a minute variation occurs in the injection amount.

According to the present invention, the bouncing is small or almost non-existent, so that the valve body starts moving from the state where it is always stopped at the valve opening position toward the valve closing position. Therefore, the time during which the valve is closed is constant, the injection amount is constant for the same Tp, and precise injection amount control is possible.

FIG. 5 shows the state of spraying immediately after the valve is closed in comparison with the prior art and the present invention.

In the conventional waveform shown in FIG. 4, since the bouncing occurs even after the valve is closed, secondary and tertiary injections are performed even after the valve is closed, as shown in FIG. Could cause significant variations. If the bouncing after closing the valve is small or not at all, the fuel is not injected after closing the valve as shown in FIG. 5 (b). The injection amount can be controlled.

As described above, according to the present invention, the bouncing of the valve element 4 can be reduced without reducing the machining accuracy of parts such as the valve element 4 and the nozzle 1 of the fuel injection valve, and the fuel injection amount can be reduced. Can be precisely controlled.

Next, another aspect of the present invention will be described with reference to FIG.

In the present invention, the interlocking member 13 is made hollow,
The inside is a fuel passage. Inner core 1 that constitutes a magnetic circuit
In the case where a fuel passage is provided in 0 or the outer iron core 14, etc.,
In order not to increase the magnetic resistance, it is necessary to increase the outer dimensions by the area of the fuel passage. However, as in the present invention, the interlocking member 1 which does not constitute a magnetic circuit is used.
If the inside of 3 is used as a fuel passage, the interlocking member 13 can be provided without increasing the outer dimensions.

The method of providing the fuel passage in the interlocking member 13 is not limited to the above. For example, interlocking member 1
One or a plurality of grooves communicating with each other in the axial direction may be provided on the outer peripheral portion of 3.

Further, another aspect of the present invention will be described with reference to FIG.

In the present invention, the interlocking member 13 is provided,
The shape of the portion of the valve body 4 that contacts the valve seat 3 is spherical.

Conventionally, there has been known a method in which the shape of the valve body 4 is spherical, and the centering function is used. However, valve seat 3
When the coaxial accuracy between the valve body 4 and the valve body 4 is poor, there are the following problems. At the time of the valve closing operation, the tip of the valve body 4 collides with one side wall of the valve seat 3 and causes lateral bouncing.
Preventing precise control of injection volume. For this reason, conventionally,
The coaxial accuracy between the valve seat 3 and the valve body 4 was strict. For example, a coaxial accuracy of 20 μm or less, preferably 5 μm or less has been required.

However, according to the configuration of the present invention, the self-centering function of the spherical surface and the effect of the interlocking member 13 attenuating the bouncing in the lateral direction at an early stage are combined, so that the valve seat 3 and the valve body 4 Coaxial accuracy can be reduced. For example, the coaxial accuracy can be reduced to 60 μm or less, preferably to about 30 μm or less.

The shape of the distal end of the valve body 4 is not limited to a ball shape as shown in FIG. 1. If the contact portion between the valve body 4 and the valve seat 3 is spherical, the shape of the other parts is not limited. Absent.
For example, the distal end shape of the valve body 4 may be a shape combining a spherical surface and a cone.

Further, another aspect of the present invention will be described with reference to FIG.

The valve element 4 has a movable iron core 5 and a rod 6. The movable iron core 5 is made of a soft magnetic material having excellent magnetic properties to form a magnetic circuit. For example, pure iron, electromagnetic stainless steel and the like are suitable, but not limited thereto. Since the rod 6 does not form a magnetic circuit, it is made of a material having relatively high hardness. For example, carbon steel, stainless steel and the like are suitable, but not limited thereto.
Also, it is desirable, but not necessary, to perform a quenching process. In the hole provided in the center of the movable iron core 5,
Through the interlocking member 13, the upper end of the rod 6 and the interlocking member 1
3 so that it contacts the lower end.

According to such a configuration, since the material of the movable iron core 5 is excellent in magnetic properties, a high electromagnetic attraction force can be secured, so that the valve element 4 can be moved at a high speed. At the same time, since the hardness of the contact portion of the valve body 4 with the interlocking member 13 is high, it is possible to ensure wear resistance against a repeated load in the axial direction.

At least one of the outer peripheral portion of the interlocking member 13, the inner peripheral portion of the inner core 10, and the inner peripheral portion of the movable iron core 5 has a surface such as quenched, nitrided or plated. It is desirable to perform a treatment to prevent sliding wear, but the present invention is not limited to this.

An example in which the fuel injection valve is mounted on an internal combustion engine will be described with reference to FIG.

The internal combustion engine 100 includes a piston 101, a cylinder 102, an intake valve 103, an exhaust valve 104, a spark plug 105, and a fuel injection valve 106. The intake valve 103 is opened and closed in accordance with the reciprocation of the piston 101, and air is introduced into the cylinder 102. Fuel is supplied to the fuel injection valve 106 from a fuel supply system such as a tank and a pump (not shown). The operation of the engine control unit and the fuel injection valve drive circuit allows the fuel injection valve 106
Is supplied to the fuel cell, and fuel injection suitable for the operation state of the internal combustion engine is performed. The mixture is ignited and burned by the ignition plug 105. The air after combustion is discharged by opening the exhaust valve 104. As described above, when the internal combustion engine is configured using the fuel injection valves described with reference to FIGS. 1 to 5, useless fuel injection due to bouncing can be prevented, and the fuel supply amount can be precisely controlled. An internal combustion engine having excellent output and exhaust characteristics can be obtained.

In FIG. 1, the means for driving the valve element 4 in the axial direction uses an electromagnetic force. However, the use of another driving means does not impair the effects of the present invention. . For example, the present invention can be applied to a case where a pressure difference is created above and below the valve element 4 using fuel pressure to drive the valve element 4 in the axial direction.

However, as shown in FIG. 1, in the case of the driving means using the electromagnetic force, the force attracted by the movable core 5 to the inner core 10 rapidly increases with the approach of both, so that the valve opening operation is performed. There is an inherent problem that bouncing at the time tends to be large. The present invention is effective for reducing bouncing during the valve opening operation.

In FIG. 1, the movable range of the valve element 4 in the axial direction is determined by the stopper 9, but the movable range of the valve element 4 is restricted by the lower end face of the inner iron core 10 instead of the stopper. Needless to say, the effects of the present invention can be obtained.

[0056]

According to the present invention, the collision energy between the valve element and the valve seat can be reduced without reducing the dimensional accuracy of the components constituting the fuel injection valve, that is, without increasing the cost.
The collision energy between the valve element and the stopper is absorbed by the displacement of the interlocking member, so that the valve element bouncing can be reduced.
This makes it possible to obtain a fuel injection valve capable of precise injection amount control.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating an embodiment of a fuel injection valve of the present invention.

FIG. 2 is a schematic diagram illustrating a valve closing operation of an embodiment of the fuel injection valve of the present invention.

FIG. 3 is a schematic diagram illustrating a valve opening operation of an embodiment of the fuel injection valve of the present invention.

FIG. 4 is a valve body displacement waveform diagram showing an effect of one embodiment of the fuel injection valve of the present invention.

FIG. 5 is a schematic diagram showing a state of spraying of the fuel injection valve of the present invention in comparison with a conventional spray.

FIG. 6 is a sectional view showing an embodiment of the internal combustion engine of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Nozzle, 2 ... Fuel injection hole, 3 ... Valve seat, 4 ... Valve element, 5
.. Movable armature, 6 rod, 7 ball, 8 shoulder part, 9 stopper, 10 inner core, 11 spring adjuster, 12 spring, 13 interlocking member, 14
... outer core, 15 ... coil.

Continued on front page (72) Inventor Makoto Yamamon 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Motoyuki Abe 502, Katsumachi-cho, Tsuchiura-shi, Ibaraki Pref. (72) Inventor Yuzo Kadokomu 502 Kandate-cho, Tsuchiura-city, Ibaraki Pref., Machinery Research Laboratories, Hitachi, Ltd. (72) Inventor Atsushi 502, Katsumachi-cho, Tsuchiura-shi, Ibaraki Pref. Inventor Yoshio Okamoto 502 Kandate-cho, Tsuchiura-city, Ibaraki Pref., Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Yoshiyuki Tanabe 7-1-1, Omikamachi, Hitachi City, Ibaraki Pref., Hitachi Research Laboratory, Hitachi, Ltd. ) Inventor Atsushi Sekine 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Car Engineering Co., Ltd. (72) Inventor Takashi Ishikawa 2520 Ojitakaba, Hitachinaka City, Ibaraki Prefecture F-term in the Automotive Equipment Division of Hitachi, Ltd. (Reference) 3G066 AA02 AB02 AD12 BA09 BA11 BA16 BA17 BA23 BA31 BA40 BA49 BA54 CC08U CC14 CC15 CC20 CC51 CC66 CD30 CE24 CE31 DA01

Claims (7)

[Claims] 1. A fuel injection hole, a valve seat disposed in the vicinity of the fuel injection hole, a valve body for opening and closing a fuel passage between the valve seat, and the valve body being attached to the valve seat. In a fuel injection valve including a spring for generating a pressing force and driving means for driving the valve element, an interlocking member separate from the valve element is provided between the valve element and the spring. Characteristic fuel injection valve. 2. A fuel injection hole, a valve seat disposed near the fuel injection hole, a valve element for opening and closing a fuel passage between the valve seat, and the valve element being attached to the valve seat. In a fuel injection valve including a spring that generates a pressing force and electromagnetic driving means that drives the valve element, an absorbing member that absorbs bouncing of the valve element is provided between the valve element and the spring. A fuel injection valve characterized by the above-mentioned. 3. The fuel injection valve according to claim 1, wherein a fuel passage is provided in the interlocking member. 4. The fuel injection valve according to claim 1, wherein a shape of a contact portion of the valve body with the valve seat is spherical. 5. The fuel injection valve according to claim 1, wherein the valve element comprises a movable core portion made of a soft magnetic material, and a rod portion made of a material having a higher hardness than the movable core. The fuel injector according to claim 1, wherein the interlocking member is configured to contact the valve body at the rod portion. 6. A fuel injection hole, a valve seat disposed in the vicinity of the fuel injection hole, a contact portion with the valve seat having a spherical shape, and a movable core portion made of a soft magnetic material; A valve element configured of a rod portion made of a material having a hardness higher than that of an iron core and opening and closing a fuel passage between the valve element and the valve seat; and a spring generating a force for pressing the valve element against the valve element, In a fuel injection valve comprising: an electromagnetic driving means for driving the valve element by an electromagnetic force acting on the valve element, an interlocking member having a fuel passage and contacting the valve element at the rod portion is formed by the valve element and the interlocking member. Between the spring,
A fuel injection valve characterized by being interposed. 7. A piston provided in a cylinder chamber, an intake valve for introducing air into the cylinder chamber, a fuel injection valve for supplying a predetermined amount of fuel to the cylinder chamber, and a spark plug for igniting the fuel And an exhaust valve for exhausting gas after combustion, wherein the fuel injection valve opens and closes a fuel passage between the valve seat disposed near a fuel injection hole and the valve seat. A valve body to be operated, a spring for pressing the valve body against a valve seat, an interlocking member separate from the valve body between the valve body and the spring, and a driving unit for driving the valve body. An internal combustion engine characterized in that: