JP2002257004A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve to promote rod-form spray of fuel and to meet requirements for emission control that has increasingly become tighter every year. SOLUTION: In the solenoid fuel injection valve, a dead volume V of fuel injection formed downstream a valve seat 12 is made to be smaller than a minimum fuel injection volume of the fuel injection. A ratio (P/Q) of a total area Q of a plurality of fuel injection holes 22 to an annular opening area P formed between a valve element 10 and the valve seat 12 is 2 to 9. From an outer periphery to a bottom face of a valve guide 20, plural fuel passage grooves 21 are formed to extend toward the inner periphery. Each connecting line of the centers of the fuel injection holes 22 is at an angle within ±15 deg. to each fuel passage groove 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection valve (injector) for an internal combustion engine used in an automobile engine or the like.
About.

[0002]

2. Description of the Related Art A fuel injection valve for an internal combustion engine is generally driven by electromagnetic force, and various types of injection holes (also referred to as nozzle holes, injection holes, etc.) for injecting fuel have conventionally been used. Proposed.

For example, in a fuel injection valve described in Japanese Patent Application Laid-Open No. 62-82268, in a pintle type, a communication space (branch orifice) in which an injection hole for measuring fuel and a fuel divided into two portions downstream thereof are injected. ) Are formed as separate members, and the area ratio between the sum of the cross-sectional areas of the communication space and the gap between the injection hole and the pintle, and the ratio between the minimum hole diameter of the communication space and the length of the branch orifice injection hole are set. Thus, the generation of vapor and the reduction of metering property are prevented.

In Japanese Patent Application Laid-Open No. 8-49622,
In a fuel injection valve provided with a single injection hole, the flow area (annular area) A1 between the valve element and the valve seat at the time of maximum lift of the valve element driven by electromagnetic force, the end of the injection hole and the valve element A2 and the flow area (cross-sectional area) B of the injection hole
Is set to B>A2> A1 to achieve atomization of fuel. In this prior art, the opening area B of the injection hole is made larger than the annular area A1 between the valve element and the valve seat.

[0005]

A fuel injection valve is arranged at one end of an intake manifold so as to face an intake port, and a plurality of injection holes are provided in a nozzle body to be directed to each intake valve of a plurality of intake valves (per cylinder). In the method of injecting fuel, it is desired to prevent the fuel spray from adhering to the intake passage wall surface as much as possible. This is because such fuel adhesion causes the fuel to flow into the cylinder in the form of droplets, which has an adverse effect on atomization of spray and measurement accuracy, and causes a reduction in exhaust gas purification.

[0006] Therefore, by reducing the spray angle together with the atomization of the fuel spray and reducing the spray angle (generally, reducing the spray angle and narrowing the spray shape is referred to as a spray-shaped rod). Attempts are made to inject fuel toward the target (intake valve).

[0007] A spray distribution measuring container (a graduated cylinder) is used to measure the fuel spray rod shape. With the measurement container facing the target (intake valve), the fuel injection valve is set at a position corresponding to the mounting, and the rod-like degree of the fuel spray is determined from the ratio of fuel entering the measurement container to the total amount of injected fuel. I have.

[0008] As a guideline of the conventional rod-shaped, even if the amount of fuel entering the measuring container is 70% or less of the whole, the specified exhaust gas regulation was satisfied. However, due to stricter exhaust gas regulations year by year, rods of fuel spray of 70% or more are required.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a fuel injection valve which promotes a rod-like fuel spray and can meet the stricter exhaust gas regulations year by year. To provide.

[0010]

SUMMARY OF THE INVENTION The present invention has made various attempts to further barify the fuel spray. As a result, it has been found that, in order to achieve the above object, it is basically preferable to configure as follows.

A valve body driven in the axial direction by an electromagnetic force;
In a fuel injection valve in which a plurality of injection holes are formed downstream of a valve seat corresponding to the valve element, a total area Q of the injection holes,
A ratio (P / Q) to an annular opening area P formed between the valve element and the valve seat during the maximum lift of the valve element is set to 2 to 9.

Further, by further setting the conditions in addition to the above configuration, the fuel spray can be further optimized.
These details will be described in the following embodiments.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a fuel injection valve according to an embodiment of the present invention, an enlarged view of a portion A, a sectional view taken along a line BB, and a sectional view taken along a line C-B of FIG.
FIG. 2A is a cross-sectional view of a nozzle 11 used for the injection valve.
And (b) is a partially enlarged view of FIG.

In this embodiment, a fuel injection valve (hereinafter, referred to as an injection) used for an engine having two intake valves per cylinder is taken as an example.

Before describing the structure of the fuel injection valve, the usage of the fuel injection valve will be described with reference to FIGS.

The intake manifold 3 has one end attached to the engine head 4 and a fuel injection valve (hereinafter, referred to as an injector) 1 attached to the intake manifold 3 so as to face the intake port 6.

The fuel delivery pipe 2 is supported above the intake manifold 3. Fuel in a fuel tank (not shown) is pumped up by a fuel pump, passes through a fuel filter, is adjusted to a predetermined pressure by a pressure regulator, and is supplied to the fuel delivery pipe 2.

The fuel delivery pipe 2 is integrally formed with a number of branch pipes 2a corresponding to the number of cylinders of the engine. The fuel supplied to the pipe 2 is distributed to each injector 1.

FIG. 4 shows that the tip 5 of the injector 1 is directed to the intake port 6 (intake valve) on the cylinder head 4 side, and fuel is injected in two directions. Injection holes for injecting fuel in a plurality of directions are drilled in the distal end portion 5 of the injector 1, and have a mounting structure for injecting fuel to each intake port.

Here, the configuration of the injector according to this embodiment will be described with reference to FIGS.

The magnetic circuit of the injector 1 includes a fixed iron core (center core) 7, an outer peripheral case (yoke) 8, and a movable iron core (plunger) 9. A part of the center core 7 is located in the center of the inside of the yoke 8, and an outer-molded electromagnetic coil 15 is arranged between the outer periphery of the center core 7 and the inner periphery of the yoke 8.

The center core 7 has a hollow fuel passage formed therein, a fuel filter 25 provided at one end, and a spring 13 for urging the plunger 9 with the valve body 10 in the valve closing direction at the other end. Inserted and the spring 13
A spring adjuster 14 for adjusting the spring load of the spring is provided.

The electromagnetic coil 15 excites the magnetic circuit described above, and includes a connector 16 for transmitting an external signal to the coil 15, a bobbin 17 for holding the coil 15, an outer mold 18 for enclosing the coil 15, and a coil assembly. A solid is formed.

A spherical valve body 10 is integrally attached to the tip (lower end) of the plunger 9 via a shoulder portion 24, and a guide ring 19 is provided at the rear end (upper end) of the plunger 9.
Is attached. The guide ring 19 is guided along the inner periphery of the core 7 when the plunger 9 moves.

Below the yoke 8, a cylindrical nozzle body 11 is mounted.

The nozzle body 11 is formed by molding a metal having corrosion resistance into a cylindrical shape, and extruding a central portion of a raised bottom portion 11B into a substantially hemispherical shape.
Two injection holes 22 are provided. On the inner surface of the extrusion,
A valve seat (sometimes called a seat portion) 12 is formed.

The configuration of the nozzle body 11 will be described in more detail.

As shown in FIG. 2A, the nozzle body 1
1 is formed as a bottomed cylindrical member 11A. The cylindrical member 11A has a hollow portion 11C provided with a valve seat 12 formed in the center of a bottom portion 11B by extrusion.
Performs valve opening and closing in cooperation with the valve element 10 (a needle valve is also possible).

The above-described injection hole 22 is provided at the bottom of the recess 11C.
Are perforated. The recess 11C is formed as a spherical surface or a conical surface. The two injection holes 22 in the embodiment shown in FIG. 2 are arranged with a predetermined divergence angle such that when the fuel injection valve is mounted on the wall surface of the intake passage, the center axes of the two injection valves are directed toward the two intake valves of the cylinder. Is established.

As another aspect of the fuel injection valve applied to the present embodiment, the fuel injection valve is used as a fuel injection valve attached to a surge tank. In this case, the two injection holes 22 are provided in the surge tank. May be formed such that the axis of the spray has a predetermined spread angle toward the opening of the independent intake pipe connected to the intake port of the cylinder.

A flat annular portion 11F having a uniform thickness is formed between the concave portion 11C and the cylindrical peripheral wall 11D on the bottom portion 11B.
Is provided.

An annular projection 11G projecting from the outer surface of the bottom 11B is formed in a specific range from the start of the depression 11C toward the center, and an injection hole 22 is formed at the center of the depression 11C. Is formed, and a constricted portion 11K is formed between the annular projection 11G and the spherical portion 11H.

Thus, the valve seat 1 against the collision of the valve element is provided.
2 while ensuring the mechanical strength of the injection hole 22 while maintaining the mechanical strength.

A guide 20 for guiding the movement of the valve body 10 is provided inside the nozzle body 11 at a position upstream of the seat. The guide 20 has a disk-shaped chip shape, the inner periphery of which serves as a guide surface for receiving the valve element 10, and a plurality of fuel passage grooves 21 formed on the outer periphery and the outer bottom surface of the chip.

A stopper 23 for determining the stroke of the valve is interposed between the nozzle 11 and the yoke 8.

When the coil 15 is energized, the core 7, the yoke 8, and the plunger 9 are excited, and the plunger 9 is
On the side, it is sucked against the force of the spring 13. When the plunger 9 moves, the valve body 10 also moves, and the nozzle 1
The valve is separated from the first valve seat 12 and opened. Here, plunger 9
Moves until the shoulder portion 24 hits the stopper 23, and the plunger 9 and the core 7 do not come into direct contact. Fuel is supplied from the filter 25 side, and is supplied to the nozzle 11 from between the yoke 8 and the plunger 9. Further, the fuel is injected through a groove 21 formed between the guide member 20 and the nozzle 11, through an annular gap formed between the valve seat 12 and the valve body 10 and two injection holes 22.

In this embodiment, the nozzle structure is configured as follows.

The volume V between the valve seat 12 and the injection hole 22 (this volume is a space surrounded by the valve body 10 when the valve is closed and the inner surface of the recess 11C having the injection hole 22 and is generally called a dead volume. Is smaller than the minimum injection amount of the fuel injection valve (the minimum injection amount during idling operation).

The dead volume is such that the valve body 10 is
If the minimum injection amount is smaller than the dead volume, the injection amount at the minimum injection amount point lacks stability. Therefore, the dead volume is set to be smaller than the minimum injection amount. For example, the injection pulse width for driving the solenoid valve is specified so that the dead volume is 0.8 mm ³ (8 cc) or less and the minimum fuel injection amount is more than that.

The total area Q of the plurality of injection holes 22 and the valve element 1
The ratio (P / Q) to the annular opening area P formed between the valve body 10 and the valve seat 12 at the time of the maximum lift of 0 was set to 2 to 9. Conventionally, P / Q is less than 2. The operating distance (maximum lift amount) of the valve body is set to 125 ± 15 μm. That is, when the maximum lift amount of the valve body is 110, P / Q corresponds to 2, and when the maximum lift amount is 130, P / Q corresponds to 9, whereby the maximum lift amount is 110 to 130. Set within the range.

The angle formed by the line connecting the centers of the injection holes 22 and the fuel passage groove 21 provided in the valve guide 20 is within ± 15 °.

As shown in FIG. 2B, the fuel injection holes 22
The ratio S / D between the distance S between the two and the injection hole diameter D is set to 0.5 or less, and the ratio L / D between the fuel injection hole length L and the injection hole diameter D is set to 1 or more.

In the embodiment, the interval S is set to (0.2 ± 0.0
2) mm. Incidentally, the wide interval S 'between the injection holes 22 is 0.39 mm, and the diameter D of each injection hole 22 is φ
(0.41 ± 0.005) mm, the length L of the injection holes 22 is (0.5 ± 0.01) mm, and the spread arrangement angle between the injection holes 22 is 7 ° ± 0.5 °.

[0045] These numerical values are merely examples.
It goes without saying that the present invention is not limited to this.

Of the above condition settings, the values of P / Q, the working distance (maximum lift amount) of the valve element, and the angle θ formed by the fuel passage groove 21 are optimized through trial and error so that the rod-shaped spray becomes 70% or more. It is obtained as a ratio or a numerical value.

For the measurement of fuel spray rod formation, a spray distribution measuring instrument is used. As shown in FIG. 4, the measuring operator sets two cylindrical measuring containers (measurement cylinders) A and B on a target (intake valve) and arranges them in a container C wider than that. The fuel injection valve is set at a position corresponding to the mounting with respect to the container, and the total amount of the injected fuel (the above containers A, B, C
The rod-like degree of the fuel spray is determined from the ratio of the fuel entering the measurement containers A and B to the fuel entering the fuel container (here, this is referred to as distribution X).

FIGS. 6 and 7 show the results of the experiment. FIG. 6 is a characteristic result obtained by examining the distribution X with respect to the valve opening stroke (maximum lift amount) S of the valve element 10. This value is obtained by setting the fuel passage groove 21 to an intermediate value ± 7.5 ° of ± 15 in FIG.
FIG. 6 is a characteristic diagram when the power supply is fixed at. FIG.
Is a result of examining the distribution X with respect to the angle θ formed by the line connecting the center of the fuel passage groove 21 and the fuel passage groove 21 when the above P / Q is fixed to an intermediate value 5.5 of 2 to 9 (maximum lift amount S = 120 μm). FIG.

That is, according to the above test results, the dead volume is smaller than the minimum injection amount of the fuel injection valve, and the P / Q is set to 2 to 9 (operating amount of the valve element 125 ± 15 μm).
m), the fuel flow is rectified when the valve is opened and closed, and the spray distribution is about 70% or more, and the spray is rod-shaped. I understand.

On the other hand, the dead volume is smaller than the minimum injection amount of the fuel injection valve, and P / Q is set to a value other than 2 to 9 (conventionally, when the operating distance of the valve element is 100 ± 10 μm,
/ Q is 2 or less), and in the case of the injector of the comparative example in which the angle θ was specified to be ± 15 ° or more, as a result of an experiment conducted under the same settings as the above conditions, the fuel flow at the time of valve opening was smaller than that of the product of the present invention. Is also sprayed in the direction that spreads outward,
The spray distribution was found to be wide at an angle of about 70% or less.

In this case, if P / Q is 2 or less, the spray distribution X
Spreads to 70% or less, and conversely if P / Q is 9 or more,
It was found that the fuel was rod-shaped, but the fuel atomization was reduced.

Table 1 summarizes the condition settings and spray forms of the product of the present invention and the injector of the comparative example. The row of the spray A is the condition set value of the present invention in which the rod-shaped spray is promoted, and the spray B is the condition set value of the comparative example in which the spray has a wider angle than the present invention.

[0053]

[Table 1] Under the conditions set in the above experiment, the ratio S / D between the distance S between the injection holes 22 and the diameter D of the injection holes was 0.5 or less, and the ratio L / L between the length L of the fuel injection holes and the diameter D of the fuel injection holes. When / D was 1 or more, a spray distribution X of about 80% was further obtained.

According to the present embodiment, the spray is formed into a thin rod shape, and the spray becomes a linear spray shape toward the intake valve. Therefore, it is possible to prevent wall flow in the intake manifold and obtain good emission. Was done.

Further, the fuel injection and the optimal injection in the form of rods in multiple directions can be realized by one member (for example, a single nozzle), so that the number of parts of the injection valve and the assembly can be simplified, and good fuel emission can be obtained. Can be

According to the present embodiment, the injection holes 22 can be formed at relatively thin portions of the bottom hollow portion 11C of the bottomed cylindrical shape, so that a plurality of injection holes are arranged in an arbitrary direction. However, the valve seat 12 can be formed with a relatively large thickness in the recess 11C, which is the same as the injection hole, so that the mechanical strength of the valve seat can be secured and the valve body 10
Impact resistance against

[0057]

As described above, according to the present invention, it is possible to provide a fuel injection valve which promotes the rod-shaped fuel spray and can meet the stricter exhaust gas regulations year after year.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fuel injection valve according to an embodiment of the present invention, and an enlarged view of a portion A, a sectional view taken along a line BB, and a sectional view taken along a line CC of the fuel injection valve.

FIG. 2A is an enlarged sectional view of a nozzle 11 used in the injection valve, and FIG. 2B is a partially enlarged view thereof.

FIG. 3 is an explanatory view showing an example of a mounting structure of a fuel injection valve.

FIG. 4 is an explanatory diagram showing an example of a spray state of fuel injection.

FIG. 5 is a distribution measurement diagram of the present embodiment.

FIG. 6 shows a valve opening stroke (maximum lift amount) of a fuel injection valve.
FIG. 6 is a characteristic diagram showing a result of examining a fuel spray distribution X with respect to S.

FIG. 7 is a characteristic diagram showing a result of examining a distribution X with respect to an angle θ formed by a line connecting a center of an injection hole and a fuel passage groove;

[Explanation of symbols]

10: valve body, 9: movable iron core, 12: valve seat, 22: injection hole.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 61/12 F02M 61/12 61/18 320 61/18 320Z 350 350Z 350E

Claims (4)

[Claims] 1. A valve body driven in an axial direction by electromagnetic force, and a fuel injection valve having a plurality of injection holes formed downstream of a valve seat corresponding to the valve body, wherein a total area Q of the injection holes is A fuel injection valve, wherein a ratio (P / Q) to an annular opening area P formed between the valve element and the valve seat at the time of maximum lift of the valve element is 2 to 9. 2. The dead volume is made smaller than a minimum fuel injection amount, and the dead volume is set to 0.8 mm.
³ or less, the operating distance of the valve is 125 ± 15μ
The fuel injection valve according to claim 1, wherein m is m. 3. A valve guide, which is located upstream of the valve seat and guides the reciprocating operation of the valve element, is provided inside a valve body having the injection hole and the valve seat formed therein. In the chip, the inner periphery becomes a guide surface of the valve body, a plurality of fuel passage grooves directed toward the inner periphery are formed from the outer periphery to the bottom surface, and a line connecting the center of the injection holes and the fuel passage groove is formed. 3. The fuel injection valve according to claim 1, wherein the angle formed is within ± 15 °. 4. The ratio S / D of the distance S between the injection holes to the diameter D of the injection holes is set to 0.5 or less, and the ratio L / D of the length L of the injection holes to the diameter D of the injection holes is set to 1 or more. The fuel injection valve according to any one of claims 1 to 3, wherein