JPH06185429A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To uniformly mix fuel with air by improving atomization of the fuel injected from a fuel injection valve. CONSTITUTION:An air passage 10 having one end opened to an end surface 6C of a needle part 6A and the other end opened to an outer peripheral side surface 6D of the needle part 6A is formed on the needle part 6A of a valve body 6 which has the needle part 6A inserted into an injection port 9A and a valve part 6B capable of being seated on a valve seat 9C.

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 used in a fuel injection device for an internal combustion engine such as a four-wheeled vehicle, a two-wheeled vehicle and the like.

[0002]

2. Description of the Related Art As a fuel supply device for an internal combustion engine, a fuel injection device using a fuel injection valve is often used in terms of improving fuel efficiency and purifying exhaust gas. As a first conventional example, there is JP-B-4-13417. In this configuration, an external pressure introducing hole is provided at a merging portion on the downstream side of the fuel injection hole, which communicates the inside of the merging portion with the outside air at the tip of the fuel injection valve. A second conventional example is Japanese Utility Model Publication No. 48-38084. This is because a protective cylinder that covers the injection valve portion is fixedly provided downstream of the fuel of the externally opened injection valve portion configured in the injection valve holder, and the inside of the injection valve holder is provided through the externally opened injection valve portion. The protective cylinder is provided with a spray passage that communicates with the fuel introduction hole, and a throttle portion is provided at the center of the spray passage, and an air suction hole is formed in the throttle portion so as to communicate the spray passage. Also, as a third conventional example, there is JP-A-59-77074. This is that the injection nozzle is wrapped by an ejector mounting portion connected to the opening of at least one air passage extending from the nozzle discharge port into the combustion chamber, and the fuel injection injected from the injection nozzle is a mixture of air from the air passage. Is.

[0003]

In such a conventional fuel injection valve, the fuel injected from the fuel injection valve is not sufficiently atomized. First, in the first conventional example,
The fuel metered to a predetermined flow rate by the fuel injection holes enters the merging portion as the adapter passage, is branched into each injection fuel passage, and is injected toward the intake pipe. Here, since the passage area of the fuel passage from the fuel injection hole is enlarged at the merging portion, the flow velocity of the fuel injected from the fuel injection hole is weakened. On the other hand, since the outside air pressure (air) is introduced by providing the outside air pressure introduction hole in the merging portion, the fuel and the air are sufficiently mixed because the flow velocity of the fuel is weakened. Without it, it is impossible to achieve atomization of fuel. Further, the fuel injected from the fuel injection holes may be condensed at the bottom of the merging portion, which also hinders atomization of the fuel.

Further, according to the second conventional example, sufficient air cannot be supplied to the injected fuel from the air suction hole, and it is difficult to atomize the fuel satisfactorily.
That is, when a negative pressure is applied from the spray flow passage on the downstream side of the throttle portion, like the throttle portion of the carburetor, a high negative pressure is generated in the throttle portion, and air is sufficiently supplied to the throttle portion from the air suction hole. However, when the pressurized fuel is injected from the spray flow passage on the upstream side of the throttle, the injection pressure acts on the throttle and a large negative pressure is applied to the throttle. Since it is difficult to generate the air, the air cannot be sufficiently sucked into the throttle portion from the air suction hole. The fuel injected from the air intake hole may be ejected in the opposite direction.

Further, according to the third conventional example, the fuel injected from the fuel passage is supplied to the ejector passage through the hollow chamber and then to the combustion chamber. At this time, the lateral air passage is provided in the ejector passage. More air is sucked in and mixed with fuel. However, since the ejector passage is a mere throttle passage and the injected fuel can freely diffuse, it is difficult to greatly increase the flow velocity of the injected fuel flowing in the ejector passage. According to this, it is not possible to greatly increase the negative pressure generated in the air passage opening to the upstream side of the ejector passage, and sufficient intake of air from the air passage and mixing of air into the fuel to remove the fuel It is difficult to make the particles fine. In this conventional example, the mixture of fuel and air can be achieved only by highly compressing the air flowing through the air passage.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a fuel injection valve in which air is sufficiently mixed with fuel injected from the fuel injection valve and the atomization of the fuel is excellent.

[0007]

In order to achieve the above-mentioned object, a fuel injection valve according to the present invention has an injection hole at its tip, and the injection hole and a valve chamber provided therein are connected by a valve seat. The valve body housing, the main body housing connected to the rear end of the valve body housing, and the axially movable body are arranged in the valve chamber of the main body housing. The tip end of the main body housing is inserted into the injection hole and protrudes from the injection hole. In a fuel injection valve including a valve body having a needle portion and a valve portion that can be seated on a valve seat, and a solenoid for axially driving the valve body in the main body housing, In the needle portion, an air passage is formed, one end of which opens at the tip end surface of the needle portion and the other end of which opens at the outer peripheral side surface of the needle portion.

[0008]

The fuel injected from the injection hole is injected along the needle portion of the valve body, and at this time, a large negative pressure is generated on the outer peripheral surface of the needle portion. According to this negative pressure, air is sucked into the air passage from the tip end surface of the needle portion, and this air is mixed with the fuel injected from the outer peripheral side surface, so that the fuel and air are sufficiently mixed and good fuel Atomization can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel injection valve according to the present invention will be described below with reference to FIGS. 1 is a vertical cross-sectional view showing a fuel injection valve, FIG. 2 is an enlarged partial cross-sectional view of portion A of FIG. 1,
FIG. 3 is a cross-sectional view taken along the line BB of FIG. 1 is
It is a substantially cylindrical main body housing that opens in the vertical direction,
From the opening at the upper end of the body housing, the solenoid 2
The solenoid 3 and the core 3 are held in the main body housing 1 by inserting the core 3 and crimping the upper end of the main body housing 1 inwardly via the upper flange portion 3A of the core 3.
Further, a fuel passage 3B is bored in the axial direction of the core 3 and is opened at the upper side to be connected to, for example, a fuel distribution pipe (not shown). Further, a terminal member 4 is provided on the upper end of the main body housing 1, and the terminal member 4 is provided with a terminal 4A connected to the solenoid 2. From the lower end of the main body housing 1, a valve holding body 5 as an armature is arranged so as to face the end of the core 3 and the valve holding body 5
The valve body 6 fixed to the core 3 is inserted, and the spring 7 is contracted between the upper end of the valve holding body 5 and the core 3. Also, the valve body 6
A valve stop plate 8 for preventing the valve holder 5 from coming off and restricting the axial movement amount of the valve element 6 is attached to the main body housing 1 on the outer periphery of the connecting portion between the main body housing and the valve holder 5. 1, the valve body housing 9 is inserted onto the valve stop plate 8 from below, and the lower end portion of the main body housing 1 is swaged inward toward the outer periphery of the valve body housing 9 to inject the valve stop plate 8 and the valve body housing. 9 can be fixed to the body housing 1. An injection hole 9A is opened at the tip (lower end in FIG. 1) of the valve body housing 9,
A valve chamber 9B for slidably holding the valve body 6 in the valve body housing 9 and the injection hole 9A are connected by a conical valve seat 9C. On the other hand, the tip end portion of the valve body 6 is inserted into the injection hole 9A and the injection side opening end portion 9D of the injection hole 9A.
The more protruding needle portion 6A and the valve portion 6B seated on the valve seat 9C are continuously formed. The above is the structure of a conventionally known fuel injection valve, and the fuel injection valve according to the present invention has the following structure added to achieve the above object.

According to the fuel injection valve of the present invention, the valve body 6
The needle portion 6A is provided with an air passage whose one end is opened to the tip end surface of the needle portion and the other end is opened to the outer peripheral side surface of the needle portion. This will be described in detail with reference to FIGS. Reference numeral 10 is an air passage provided in the needle portion 6A of the valve body 6, and this air passage 10 is an air suction passage 10A.
And the air suction passage 10B. Air intake passage 10A
Has one end opened to the tip surface 6C of the needle portion 6A,
The needle portion 6A is bored upward in the axial direction. The tip surface 6C refers to a side that is substantially orthogonal to the axial direction of the needle portion 6A and excludes the outer circumference. The air suction passage 10B is
One end thereof opens to the air intake passage 10A, and the other end opens to the outer peripheral side surface 6D of the needle portion 6A. Thus, one end of the air passage 10 serves as the air suction passage 10A and the needle portion 6A is formed.
6C, and the other end opens to the outer peripheral side surface 6D of the needle portion 6A through the air suction passage 10B.

Next, the operation will be described. In the fuel injection valve, when the solenoid 2 is demagnetized, the valve body 6 is pressed toward the valve seat 13 by the spring force of the spring 7 via the valve holding body 5, so that the valve portion 6B of the valve body 6 is closed. The fuel is not injected from the injection hole 9A by being in contact with the seat 9C. On the other hand, when the solenoid 2 is excited, the valve holding body 5 is attracted to the core 3 against the spring force of the spring 7, and the valve portion 6B of the valve body 6 separates from the valve seat 9C to the valve stop plate 8. By moving axially until it abuts, the valve portion 6B
A gap is formed between the valve seat and the valve seat 9C. Thus, the fuel pressurized and flowing from the fuel flow path 3B is injected to the outside from the injection side opening end portion 9D of the injection hole 9A via the valve chamber 9B. At the time of fuel injection from such a fuel injection valve, particular attention should be paid to the following. That is,
The fuel injected with a positive pressure (usually 2.55 kg / cm2) from the injection hole 9A is the injection side opening end 9 of the injection hole 9A.
After passing through D, the outer peripheral side surface 6 of the needle portion 6A of the valve body 6
It flows down along D and is injected into an intake pipe (not shown) with a spray angle diffused. Generally, this spray angle is set in the range of 10 to 40 degrees. When fuel having a high flow velocity is injected and passes through the outer peripheral side surface 6D of the needle portion 6A, a large negative pressure is generated on the outer peripheral side surface 6D of the needle portion 6A, while the tip of the needle portion 6A is On the surface 6C, a large negative pressure is not generated because the surface 6C faces the inside of the intake pipe. According to the above,
A large pressure difference is generated between the outer peripheral side surface 6D and the tip surface 6C of the needle portion 6A, and an air flow is generated from the air suction passage 10A as the air passage 10 toward the air suction passage 10B, and the air suction passage 10B. Air is sucked and mixed with the inner portion of the injected fuel flowing through the outer peripheral side surface 6D of the needle portion 6A. The air sucked into the injected fuel expands along with the diffusion of the fuel and flows downward while mixing toward the outer side, which makes the injected fuel even from the inner portion to the outer portion. In addition, the air can be mixed well, and the atomization of the fuel can be remarkably improved. Furthermore, the provision of the air passage 10 in the needle portion 6A means that air can be mixed into the fuel before the fuel injected from the injection hole 9A largely diffuses (immediately before the diffusion). At the time of diffusion, air can be mixed by utilizing the diffusion energy of the fuel, and the atomization of the fuel can be effectively performed. In addition, since it is not necessary to provide new parts for the conventional fuel injection valve, it is possible to suppress the cost increase due to the increase in the number of parts and to have compatibility with the fuel injection valve used conventionally,
Moreover, it does not require any change in the attachment to the engine, and its implementation is extremely easy. The air passage 10
Does not necessarily require the two passages of the air suction passage 10A and the air suction passage 10B. As shown by the alternate long and short dash line in FIG. Can also be Furthermore, since the opening of the air suction passage 10B is opened in the outer peripheral side surface 6D of the needle portion 6A in the vicinity of the injection side opening end portion 9D of the injection hole 9A, extremely high fuel injected from the injection hole 9A can be obtained. Since the air can be mixed with the fuel injected from the air suction passage 10B with a flow velocity, the atomization of the fuel can be improved more effectively. This air suction passage 10B is shown by a one-dot chain line in FIG. Furthermore, the structure of the fuel injection valve itself is not limited to the structure as shown in the figure, and the point is that the valve body may be provided with a needle portion.

A second embodiment is shown in FIGS.
(The same reference numerals are used for the same structural parts as in FIG. 2.) In the present embodiment, a plurality of air suction passages 10B are provided in the cross section of the needle portion 6A, and according to this, mixing of air with fuel is more effective. And the atomization of the fuel is further improved.

FIG. 6 shows a third embodiment. (The same reference numerals are used for the same structural parts as those in FIG. 2.) In this embodiment, the air suction passages 10B are provided in multiple stages in the axial direction of the needle portion 6A. According to this, mixing of air with fuel is more effective. And the atomization of the fuel is further improved.

A fourth embodiment is shown in FIGS. 7 and 8.
(The same reference numerals are used for the same structural parts as those in FIG. 2.) This embodiment is a combination of the second embodiment and the third embodiment, and the effects of both are obtained in a reciprocal manner. Therefore, it is possible to achieve even better fuel atomization.

[0015]

As described above, according to the fuel injection valve of the present invention, air is sucked and mixed in the fuel injected from the outer peripheral side surface of the needle valve by the pressure difference utilizing the injection energy of the fuel. It is possible to diffuse the fuel from the inner part of the fuel near the outer circumference of the valve to the outer part and to mix the air uniformly with the fuel, which can greatly improve atomization of the fuel.
Furthermore, since air is sucked into the fuel immediately before the fuel injected from the injection hole diffuses, the air can be mixed well by the diffusion energy of the fuel. Further, since the air passage need only be formed by drilling holes in the conventional needle portion and it is not necessary to increase the number of parts, it is possible to suppress an increase in manufacturing cost, and further, it is possible to prevent the air passage from the conventional fuel injection valve. It is compatible and does not require any changes to other components such as the intake manifold to which the fuel injection valve is attached, and can be adopted very easily.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a fuel injection valve according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion A of FIG.

3 is a cross-sectional view taken along the line BB of FIG.

FIG. 4 is an enlarged cross-sectional view of essential parts showing a second embodiment of the present invention.

5 is a cross-sectional view taken along the line CC of FIG.

FIG. 6 is an enlarged cross-sectional view of an essential part showing a third embodiment of the present invention.

FIG. 7 is an enlarged sectional view of an essential part showing a fourth embodiment of the present invention.

8 is a cross-sectional view taken along the line DD of FIG.

[Explanation of symbols]

 6 Valve body 6A Needle part 6B Valve part 6C Tip surface 6D Outer peripheral side surface 9 Valve body housing 9A Injection hole 9C Valve seat 10 Air passage

Claims (5)

[Claims] 1. A valve body housing having an injection hole at its tip, which connects the injection hole and a valve chamber provided inside with a valve seat, and a main body housing connected to a rear end of the valve housing. A valve element that is axially movably arranged in the valve chamber of the main body housing and has a needle portion that is inserted into the injection hole at its tip and that projects from the injection hole, and a valve portion that can be seated on the valve seat, In a fuel injection valve provided with a solenoid for axially driving the valve body in the main body housing, in the needle portion 6A of the valve body 6, one end is opened to the tip surface 6C of the needle portion 6A, The other end is the needle portion 6A
A fuel injection valve having an air passage 10 that is open to the outer peripheral side surface 6D. 2. An opening to an outer peripheral side surface 6D of a needle portion 6A of the air passage 10 is formed by an injection side opening end portion 9 of an injection hole 9A.
The fuel injection valve according to claim 1, wherein the fuel injection valve is opened in the vicinity of D. 3. The fuel injection valve according to claim 1, wherein a plurality of openings to the outer peripheral side surface 6D of the needle portion 6A of the air passage 10 are formed in the cross section of the needle portion 6A. 4. The fuel injection valve according to claim 1, wherein the opening of the needle portion 6A of the air passage 10 to the outer peripheral side surface 6D is opened in multiple stages in the axial direction of the needle portion 6A. 5. The opening of the needle portion 6A of the air passage 10 to the outer peripheral side surface 6D is plural in the cross section of the needle portion 6A, and is opened in multiple stages in the axial direction of the needle portion 6A. Fuel injection valve.