JPH11336643A - Electromagnetic fuel injection valve for cylinder injection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve ignitability and combustibility of an engine by providing a collision wall having a larger face than the diameter of a fuel jet and extended axially downstream on either one face side of a face passing the center of the fuel jet. SOLUTION: A nozzle member 7 is provided with a collision wall 25 integrally formed at the tip. The collision wall 25 is positioned slightly separated from a jet 8 and extended axially downstream on either one face side of a face passing the center of the jet 8. The length of a plane facing the jet 8 is sufficiently longer than the diameter of the jet 8. Fuel spray with partially strong flow can be added into widely dispersed fuel spray with swirling force effectively imparted by a fuel swirling element 22, by the collision wall 25 provided at the outlet part of the fuel jet 8. Ignitability of an engine is therefore made excellent, and lean-burn is realized to reduce the exhaust quantity of unburnt gas components and to improve fuel consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which gasoline is directly injected into a combustion chamber and burns it (hereinafter referred to as a direct injection gasoline engine), and can be adapted to a combustion situation which varies widely depending on a load. The present invention relates to an in-cylinder injection electromagnetic fuel injection valve that can be injected with spray characteristics.

[0002]

2. Description of the Related Art An in-cylinder fuel injection device that injects fuel directly into a combustion chamber is known, while an in-pipe fuel injection device that injects fuel into an intake pipe of an engine is known.

As such a direct injection gasoline engine, there is JP-A-6-146886. In this reference, lean combustion is performed with a fuel leaner than the stoichiometric air-fuel mixture by considering the mounting position of the fuel injection valve and forming a vertical vortex intake flow in the combustion chamber by an intake port extending upward from the intake opening end. It is intended to stabilize and improve fuel efficiency.

On the other hand, the in-cylinder injection gasoline engine studied by the present inventors generates an intake swirl flow in a combustion chamber and attempts to realize lean combustion without largely changing the cylinder head of the conventional engine. is there. Less than,
The spray forming method for ensuring stable combustion will be described with reference to FIG. As will be described in detail later, the electromagnetic fuel injection valve attached to the direct injection gasoline engine is attached to the cylinder head at an inclination of about 30 ° to 45 °, and its injection hole is formed in a cavity (a concave portion) provided in the piston. ).

[0005] This type of direct injection gasoline engine selectively uses homogeneous combustion and stratified combustion depending on the load. According to the authors' experimental analysis results, in homogeneous combustion, the uniform spray is effective at a wide spray angle to diffuse the spray throughout the combustion chamber and homogenize the air-fuel mixture. It was found that it was effective to create a partially strong flow in the spray because it was necessary to guide combustible vapor around the plug. On the other hand, it was found that in the stratified combustion, a compact spray with a small spray angle is effective to prevent excessive dispersion of the air-fuel mixture and concentrate combustible vapor around the spark plug.

[0006]

As described above, in homogeneous combustion, sprays that are widely dispersed and partially strong flow are required, and in stratified combustion, compact sprays are required. Have used a swirl-type electromagnetic fuel injection valve to generate the pressure.

[0007] The swirl type spray has a hollow conical shape having a cavity inside at atmospheric pressure. The liquid film at the outlet of the fuel injection hole is rapidly divided and atomized, and the momentum of the droplet is immediately lost, thereby suppressing the penetration. For this reason, a widely dispersed spray is relatively easy to obtain, but on the other hand, a partially strong flow cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electromagnetic fuel injection valve capable of generating a spray having a partially strong flow even at atmospheric pressure. An object of the present invention is to provide an in-cylinder injection type electromagnetic fuel injection valve in which both ignition performance and combustion performance are improved.

[0009]

In the swirl type spray, the penetration is suppressed by the increase in the atmospheric density under the pressurization, and the spray is reduced by the pressure difference between the inside and the outside of the spray. Becomes In stratified combustion, fuel is injected during the compression stroke (the piston rises and the pressure in the combustion chamber increases)
Such a shape change is preferred. Therefore, in a direct injection gasoline engine that uses homogeneous combustion and stratified combustion selectively, it is possible to achieve both ignitability and flammability by adjusting and adding a partly strong flow to spray under atmospheric pressure.

For this purpose, the in-cylinder electromagnetic fuel injection valve of the present invention has a fuel passage through which fuel is formed, a valve member for opening and closing the fuel passage, and a valve member for the valve member. A fuel swirling member for turning fuel on the upstream side of the valve seat, and a fuel injection hole for allowing the passage of fuel on the downstream side of the valve seat; Providing a collision wall having a surface larger than the diameter of the fuel injection hole and extending axially downstream on one side of a surface passing through the center of the fuel injection hole, and the collision wall partially collects spray. And a strong flowing spray.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view of an in-cylinder electromagnetic fuel injection valve 1 showing one embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing an enlarged valve portion, and FIG. 4
5 is a schematic diagram showing the flow of the spray in the cylinder. The structure and operation will be described with reference to each drawing.

The electromagnetic fuel injection valve 1 performs fuel injection by opening and closing a seat portion in response to a duty ON-OFF signal calculated by a control unit. The magnetic circuit includes a core 2 including a bottomed cylindrical yoke 3, a plug 2 a for closing an open end of the yoke 3, and a columnar portion 2 b extending to the center of the yoke 3, and a plunger facing the core 2 with a gap therebetween. 4 At the center of the columnar portion 2b, a movable portion 4A composed of a plunger 4, a rod 5, and a ball valve 6 is pressed against a seat surface 9 on the upstream side of an injection hole portion 8 formed in a nozzle member 7 to allow passage of fuel. A hole for inserting and holding a spring 10 as an elastic member is provided. The upper end of the spring 10 is in contact with the lower end of a spring adjuster 11 inserted into the center of the core 2 to adjust the set load.

A gap facing the columnar portion 2b of the core 2 and the movable portion 4A of the yoke 3 has a seal ring 12 mechanically fixed between the two to prevent fuel from flowing out to the coil 14 side. Is provided. A coil 14 for exciting a magnetic circuit is wound around a bobbin 13 and its outer periphery is molded with a plastic material. The terminals 17 of the coil assembly 15 composed of these are inserted into holes 16 provided in the flange of the core 2. The terminal 17 is connected to a terminal of a control unit (not shown). A plunger receiving portion 18 for receiving the movable portion 4A is opened at the bottomed portion of the yoke 3, and a nozzle formed to have a diameter larger than that of the plunger receiving portion 18 at a lower portion thereof to receive the stopper 19 and the nozzle member 7. The receiving portion 20 extends through to the tip of the yoke.

The movable part 4A is a plunger 4 made of a magnetic material.
And a ball 5 joined at one end to the plunger 4 and a ball 6 joined at the other end of the rod 5.
The plunger 4 is provided with a cavity 5A that allows the passage of fuel. The cavity 5A is provided with a fuel outlet 5B. The movable portion 4A is guided in its axial direction by the outer periphery of the plunger 4 abutting against the seal ring 12, and the ball 6 joined to the other end is attached to the inner wall 21 of the hollow portion of the nozzle member 7. Each is guided by contacting the inner wall of the cylindrical fuel swirl element 22 to be inserted. The nozzle member 7 is provided with a seat surface 9 for seating the ball valve 6 following a cylindrical fuel swirl element 22 for guiding the ball valve 6, and the center of the seat surface 9 allows passage of fuel. An injection hole 8 is provided. The stroke of the movable portion 4A (the amount of upward movement) is
Is determined by the size of the gap between the receiving surface 5a of the neck portion and the stopper 19. A filter 26 is provided to prevent dust and foreign matter in the fuel and pipes from entering the sheet.

At the tip of the nozzle member 7, an integrally formed collision wall 25 according to the present invention is provided. Here, the operation will be described with reference to FIGS.
FIG. 2 is an enlarged cross-sectional view of the vicinity of the tip portion, and FIG. 3 is a view in the direction A of FIG.

The collision wall 25 is located at a position slightly distant from the injection hole 8, and extends axially downstream to one of the surfaces passing through the center of the injection hole 8. The length of the plane facing the injection hole 8 is sufficiently larger than the diameter of the injection hole 8. In the embodiment, the cross section is shown as a three-month type, but the surface corresponding to the injection hole 8 may be deformed such as to be slightly curved.

Returning to the description, the fuel swirling element 22 is provided with an axial groove 23 and a radial groove 24. In the present embodiment, the axial groove 23 is formed by a D-cut surface, but may be another shape such as an annular passage. The axial groove 23 and the radial groove 24 are fuel passages that are introduced from above the valve. Fuel passing through the axial groove 23 is eccentrically introduced from the axial center by the radial groove 24. In other words, the fuel is swirled to promote atomization when the fuel is injected from the injection holes 8 provided in the nozzle member 7. Here, the swirling strength (swirl number S) provided by the fuel swirling element 22 is obtained by the following equation.

[0018]

[Number 1] S = (angular momentum) / (momentum injection axis direction) × herein (orifice _{radius) = 2 · d 0 · Ls} / n · ds 2 · cos θ / 2, d 0: the fuel injection holes Diameter Ls: Eccentric amount of groove n: Number of grooves θ: Angle of valve seat ds: Rheologically equivalent diameter, expressed using groove width W and groove height H.

= 2 · W · H / W + H. Increasing the swirl number promotes atomization and disperses the spray.

The operation of the injection valve 1 configured as described above will be described. The injection valve 1 operates the movable part 4A to open and close the valve seat surface 9 in response to an electrical ON-OFF signal given to the electromagnetic coil 14, thereby performing fuel injection control. When an electric signal is applied to the coil 14, a magnetic circuit is formed by the core 2, the yoke 3, and the plunger 4, and the plunger 4 is attracted to the core 2. When the plunger 4 moves, the ball valve 6 integrated therewith
Also moves away from the seat surface 9 of the valve seat of the nozzle member 7 to open the injection hole 8. The fuel is pressurized and adjusted via a fuel pump (not shown) or a regulator that adjusts the fuel pressure.
The fuel flows into the injection valve 1 from the filter 26, and passes through the lower passage of the coil assembly 15, the outer peripheral portion of the plunger 4, the gap between the stopper 19 and the rod 5, the grooves 23 and 2 of the fuel swirling element 22.
4, is swirled and supplied to the seat portion, and is injected through the injection hole 8 into the combustion chamber of the engine.

Here, the flow will be described with reference to FIGS. 4 and 5, which schematically show the spray form.

FIG. 4 shows how the fuel is injected during the intake stroke. Spray that has a widely dispersed spray and a spray that has a partially strong flow. This corresponds to the idle operation and high load operation of the direct injection gasoline engine, and the mixture is homogenized to perform combustion (homogeneous combustion). carry out. Such spray can be obtained by sufficiently increasing the swirling strength (swirl force) of the fuel. In the present embodiment, the amount of eccentricity Ls (distance between the groove center and the axis) of the groove 23 of the fuel swirling element 22 is increased. ing. When the swirl force is sufficiently increased, the pressure energy of the fuel is replaced by the swirling velocity energy at the injection holes 8 and the film formation of the fuel proceeds. Thereafter, the liquid film sprayed in the shape of a hollow cone is rapidly divided and atomized, the momentum of the droplet is lost, the penetration is suppressed, and the liquid film is uniformly dispersed. further,
In the present embodiment, since the collision wall 25 is provided at the outlet of the injection hole 8, a part of the liquid film is collected by the effect of adhesion to the collision wall 25, and a partially strong flow as shown in FIG. Generate. This partially strong flow is arranged towards the piston cavity, which is further deflected at the R-plane of this cavity and towards the spark plug so as to entrain a part of the dispersed spray.

FIG. 5 shows the flow of the spray injected in the latter half of the compression stroke. In response to partial load operation of the direct injection gasoline engine, stratified charge combustion is performed by leaning the mixture. In the latter half of the compression stroke, the pressure in the combustion chamber becomes
Since the pressure rises by about 5 MPa, the penetration of the spray is suppressed by the increase in the atmosphere density, and the spray is deflated by the pressure difference between the inside and the outside of the spray, forming a compact spray as shown in FIG.
Except for this portion, the combustion chamber is diluted to produce a stratified mixture.

FIGS. 6 and 7 show a second embodiment of the present invention. FIG. 7 is a view as viewed in the direction B in FIG. In this embodiment, a nozzle cover 27 having a collision wall 28 is provided on the nozzle member 7. The difference from the first embodiment is that the collision wall 28 is formed separately from the nozzle member 7, whereby the injection valve can be manufactured at low cost. When the material of the nozzle cover 27 is made of a material having good thermal conductivity, the temperature is raised during combustion, and a self-cleaning effect of deposits (which is a gasoline or an engine lubricating oil mixed with gasoline which is being carbonized) can be obtained. Can be Also in this embodiment,
The spray forms shown in FIGS. 4 and 5 are obtained, and the same operation and effects as those of the first embodiment are obtained.

FIGS. 8 and 9 show a third embodiment of the present invention. FIG. 9 is a view in the direction C of FIG. In this embodiment, a step is provided at the outlet portion of the fuel injection hole 30. At the time of fuel injection, the spray is partially collected on the end face side 29 where the injection hole length is large, and a strong flow of the spray is obtained. It is configured so that Unlike the first embodiment and the second embodiment, since the injection valve is configured by partial additional processing, the injection valve can be manufactured at lower cost.

Next, the configuration and combustion operation of the in-cylinder direct-injection gasoline engine 60 used in the study by the present inventors will be described with reference to FIG. The figure shows an enlarged view of a main part around the engine. Reference numeral 61 denotes an intake air amount control device having a built-in throttle valve, and reference numeral 62 denotes an intake manifold to which the intake air amount control device 61 is attached. A cylinder head 63 is provided with an intake valve 64 on the intake manifold 62 side, a spark plug 65 in the center, and an exhaust valve 66 on the side opposite to the intake valve 64. The in-cylinder electromagnetic fuel injection valve 1 according to the present invention includes an intake manifold 62 of a cylinder head 63.
It is attached at an angle of 30 ° to 45 ° in the vicinity of the joint with the above. The injection direction is fixed so as to be directed to a cavity 69A provided in a piston 69 in the combustion chamber 67. 68 is a cylinder. In the drawing, white arrows indicate the flow of intake air, and hatched arrows indicate the flow of exhaust gas.

In this gasoline engine, the combustion state is controlled by the load as follows. At partial load, stratified charge combustion is performed by late-stage in-cylinder injection (compression stroke injection), and at high load, homogeneous combustion is performed by the in-cylinder injection (intake stroke injection). In the stratified combustion, a layer of a rich air-fuel mixture is formed in the vicinity of the ignition plug 65 to realize stable combustion of a lean air-fuel mixture. In the homogeneous combustion, the mixture is homogenized in the entire combustion chamber, thereby realizing the premixed lean combustion. These aim at realizing low fuel consumption and high output at the same time, and the spray injected from the in-cylinder electromagnetic fuel injection valve 1 is generated at the timing of intake, compression, and the like. . The injection signal is issued by a control unit (not shown) based on the operation information of the engine. The figure shows the situation of fuel injection during the intake stroke, in which the spray fuel promotes mixing with air in the combustion chamber 67. At this time, the spray having a strong flow partially in the spray The flow direction is regulated by 69A. That is, the flow is directed toward the ignition plug 65 as indicated by the dark arrow in the drawing. On the other hand, small-diameter droplets having a low velocity are generated in the combustion chamber 6.
7 to promote mixing with air. After a while
The air-fuel mixture is compressed in the compression stroke and ignited by the spark plug 65, thereby realizing stable lean combustion in which the amount of unburned gas discharged is suppressed.

[0028]

As described above, according to the present invention,
The spray having a strong flow can be added partially by the collision wall provided at the outlet of the fuel injection hole during the widely dispersed spray obtained by the swirling force being effectively applied by the fuel swirling element. When such a spray is supplied to the combustion chamber of a direct injection gasoline engine, the flow of the spray and the dispersion of the small-diameter droplets improve the ignitability of the engine. The amount is reduced and the fuel efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an in-cylinder electromagnetic fuel injection valve according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the vicinity of a leading end portion of the in-cylinder electromagnetic fuel injection valve of the present invention.

FIG. 3 is a front view as viewed from a direction A in FIG. 2;

FIG. 4 is a schematic view of spraying during intake stroke injection (under atmospheric pressure).

FIG. 5 is a schematic view of spraying in compression stroke injection (under pressure).

FIG. 6 is a sectional view of the vicinity of a leading end of an electromagnetic fuel injection valve according to a second embodiment of the present invention.

FIG. 7 is a front view as viewed from a direction B in FIG. 6;

FIG. 8 is a sectional view of the vicinity of an injection hole portion of an electromagnetic fuel injection valve according to a third embodiment of the present invention.

FIG. 9 is a front view as viewed from a direction C in FIG. 6;

FIG. 10 is an enlarged view of a main part of a direct injection gasoline engine incorporating the electromagnetic fuel injection valve of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic fuel injection valve, 6 ... Ball valve, 8 ... Fuel injection hole, 22 ... Fuel swirl element, 23 ... Axial groove, 24 ... Radial groove, 25 ... Collision wall.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Yamamon 502, Kandachi-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. Hitachi, Ltd.Automotive Equipment Division (72) Inventor Yasuhisa Hamada 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Within Hitachi Car Engineering Co., Ltd.

Claims (3)

[Claims] 1. An electromagnetic fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, wherein a valve member for forming a fuel passage through which fuel flows and opening and closing the fuel passage is provided. A fuel swirling member for turning fuel on the upstream side of the valve seat of the valve member; and a fuel injection hole for allowing passage of fuel on the downstream side of the valve seat. And a collision wall having a surface that is larger than the diameter of the fuel injection hole and extends axially downstream on one of the surfaces passing through the center of the fuel injection hole. Electromagnetic fuel injection valve for internal injection. 2. An electromagnetic fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, the valve including a fuel passage through which fuel flows, and a valve member for opening and closing the fuel passage. A fuel swirling member for turning fuel on the upstream side of the valve seat of the valve member; and a fuel injection hole for allowing passage of fuel on the downstream side of the valve seat. A collision wall having a surface larger than the diameter of the fuel injection hole and extending downstream in the axial direction on one of the surfaces passing through the center of the fuel injection hole. An electromagnetic fuel injection valve for in-cylinder injection, characterized in that the fuel is partially collected to form a strong flowing spray. 3. An electromagnetic fuel injection valve for directly injecting fuel into a combustion chamber of an internal combustion engine, wherein a valve member for forming a fuel passage through which fuel flows and opening and closing the fuel passage is provided. A fuel swirling member for turning fuel on the upstream side of the valve seat of the valve member; and a fuel injection hole for allowing the passage of fuel on the downstream side of the valve seat, wherein the end face of the fuel injection hole is provided. Is characterized in that it has a partly stepped portion, and at the time of fuel injection, the spray is partially collected on the end face side where the length of the injection hole is large to form a strong flow spray. Electromagnetic fuel injection valve for injection.