JPH07145767A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To provide a fuel injection valve capable of promoting atomization of injected fuel without using special auxiliary devices and parts. CONSTITUTION:In a fuel injection valve in which a valve seat 16, a flow passage part 17, and an injection hole 18 are formed in a nozzle body 10, and fuel is injected toward an outside the space 6 through the injection hole 18 when a needle 20 is separated from the valve seat 16. Air suction passages 19a-19c for introducing air from a space by mutually communicating the low pressure generation part of the flow passage part 17 and the space 6. Therefore fuel flow is rapidly varied because flow passage formation is varied in the flow passage part 17 from the valve seat 16 to the injection hole 18, and then a low pressure is generated by peeling, and then the air is sucked from a space outside the air suction passages 19a-19c to this low pressure part. 7 Accordingly, the fuel and the air are mixed together in the flow passage part 17, and the 7 mixed fuel is injected through the injection hole 18, and then atomization of the fuel is promoted.

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 which promotes atomization of fuel injected from an injection hole to reduce exhaust gas and improve fuel efficiency.

[0002]

2. Description of the Related Art In a device for injecting fuel into an internal combustion engine, when the atomization of the fuel injected from an injection valve is promoted, the ignitability of the fuel is improved, good combustion is secured, noise is reduced and exhaust gas It is known to be effective in reducing harmful components and improving fuel efficiency. It is also known that in order to atomize the injected fuel, air is mixed with the fuel and the mixed fuel is injected from the injection hole, and the fuel is crushed and atomized by the resistance of the air.

For this reason, in the past, the actual Kaihei 2-110252 was used.
The device disclosed in the publication is proposed. The technique described in the above publication has a structure in which air is pressurized by a supercharger, the high-pressure air is guided to a fuel injection valve through a pipe, mixed with fuel inside the injection valve, and injected from an injection hole. There is.

[0004]

However, the conventional fuel injection device disclosed in the above publication requires special auxiliary equipment such as a supercharger and parts such as pipes, which not only increases the number of parts. However, there is a problem that the mountability of these auxiliary devices in a vehicle becomes a problem, and the price increases.

The present invention has been made in view of such circumstances, and an object thereof is to provide a fuel injection valve capable of promoting atomization of injected fuel without using special auxiliary equipment or parts. Is what you are trying to do.

[0006]

In order to achieve the above-mentioned object, the present invention has a nozzle body, a valve seat, a flow passage portion continuous downstream of the valve seat, and an injection opening at the end of the flow passage portion. A fuel injection valve that forms a hole and accommodates a needle, and injects fuel through the injection hole toward a space where the injection hole is opened when the seat portion of the needle is separated from the valve seat, An air intake passage, which communicates with the space and introduces air from the space, is opened in the low-pressure generating portion of the flow passage portion, the fuel and air are mixed in the flow passage portion, and the mixed fuel is passed through the injection hole. It is characterized by jetting.

[0007]

According to the structure of the present invention, when the seat portion of the needle separates from the valve seat, the fuel flows along the valve seat into the flow passage portion and is injected from the flow passage portion to the external space through the injection hole.
In this case, since the shape of the flow passage changes in the flow passage from the valve seat to the injection hole, the fuel flowing along the valve seat surface flows rapidly at the place where the fuel enters the flow passage and the inlet of the injection hole. Changes, which creates a low pressure part. Air is automatically introduced into the low-pressure portion from the external space through the air intake passage, so that the fuel and the air are mixed in the flow passage and the mixed fuel is injected through the injection hole. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to FIGS.
A description will be given based on the first embodiment shown in FIG. FIG. 1 is an enlarged view of a nozzle tip portion showing a configuration of the present invention, and FIG. 2 is a configuration diagram showing an entire fuel injection system using a fuel injection valve of the present invention. In FIG. 2, 1 is a fuel injection valve, 2 is a fuel injection pump, and 3 is a fuel supply pipe. The fuel injection pump 2 is, for example, a row-type fuel injection pump.
Distributes and supplies a predetermined amount of fuel to the fuel injection valves 1 of each cylinder through the fuel supply pipes 3 at a predetermined timing according to the operating condition of the engine.

Explaining the fuel injection valve 1, 10 is a nozzle body, 11 is a nozzle holder, and 12 is a retaining nut for fastening the nozzle body 10 and the nozzle holder 11. 13 is the nozzle body 1
It is a packing plate held between 0 and the nozzle holder 11.

A guide hole 14 is formed in the nozzle body 10, and a needle 20 is slidably accommodated in the guide hole 14. A fuel reservoir 15 is formed at the lower end of the guide hole 14. And the nozzle body 10
A valve seat 16 is provided at the tip of the valve so as to communicate with the fuel reservoir 15, and the flow passage 17 shown in FIG. 1 and the end of the flow passage 17 shown in FIG. An injection hole 18 that is open to the inside is formed. The nozzle body 10 is attached to the engine 5, and the tip of the nozzle body 10 faces the combustion chamber 6 of the engine 5, so that the injection hole 18 is opened to the combustion chamber 6 of the engine 5. This combustion chamber 6 corresponds to the space of the present invention.

The needle 20 has a seat portion 21 at the lower end.
The seat portion 21 contacts and separates from the valve seat 16 formed on the nozzle body 10 to open and close the injection hole 18. An inclined pressure receiving surface 22 is formed in the middle of the needle 20 so as to face the fuel reservoir 15. Therefore, when the fuel pressure in the fuel reservoir 15 exceeds a predetermined value, the needle 20 is pushed up and the seat portion 21 separates from the valve seat 16, whereby the fuel in the fuel reservoir 15 is transferred to the valve seat 16, the flow passage portion 17, and the flow passage portion 17. Injection hole 18
Is injected into the combustion chamber 6 through.

A spring chamber 24 is formed in the nozzle holder 11, and a coil spring 25 is housed in the spring chamber 24. This coil spring 25 has a shim 26 at one end.
And the other end is in contact with the pressure pin 27 as a spring seat. This pressure pin 2
7 is locked to the upper end of the needle 20. The upper end of the needle 20 penetrates the packing plate 13 and is guided to the spring chamber 24. Therefore,
The needle 20 is pushed down by the pressing force of the coil spring 25, whereby the seat portion 21 is seated on the valve seat 16 and the injection hole 18 is closed.

The spring chamber 24 communicates with a fuel tank (not shown) through a fuel escape passage 28 so that fuel leaking into the spring chamber 24 can escape. The fuel reservoir 15 includes the nozzle body 10 and the packing plate 1.
3 and the nozzle holder 11 are connected to a fuel introduction passage 29 formed therein, and the fuel supply pipe 3 is connected to the fuel introduction passage 29.

Therefore, when a predetermined amount of fuel is supplied from the fuel injection pump 2 to the fuel introduction passage 29 through the fuel supply pipe 3 at a predetermined timing according to the operating condition of the engine, the fuel pressure in the fuel reservoir 15 is increased. When the fuel pressure rises and the fuel pressure rises above the valve opening pressure against the pressing force of the coil spring 25, the needle 20 is pushed up, and thus the seat portion 2
1 moves away from the valve seat 16. As a result, the fuel in the fuel reservoir 15 is injected into the combustion chamber 6 through the valve seat 16, the flow passage 17 and the injection hole 18.

When the fuel pressure in the fuel reservoir 15 becomes weaker than the force set by the pressing force of the coil spring 25 after the predetermined fuel injection is completed, the needle 20 is pushed down and the seat portion 21 is seated on the valve seat 16. Sit down. As a result, the injection of fuel from the injection hole 18 ends.

By the way, in this embodiment, as shown in FIG. 1, an air intake passage 19 is opened in the flow passage portion 17 located between the valve seat 16 formed in the nozzle body 10 and the injection hole 18. There is. The number of the air intake passages 19 may be one or more. In this embodiment, the plurality of air intake passages 1 are provided.
9a to 19d are formed. These air intake passages 19
a to 19d are located on the downstream side of the boundary between the valve seat 16 and the flow path portion 17, upstream of the opening end portion of the injection hole 18, and are opened to the flow path portion 17, and The end is the injection hole 1
8 is opened to the open space, that is, to the combustion chamber 6. These air intake passages 19a to 19d are provided in the combustion chamber 6
It is possible to introduce air (including the case of exhaust gas), however, it is formed in a size such that the fuel in the flow path portion 17 does not pass through, for example, a diameter of 0.02 to 0.08 mm.

The operation of the fuel injection valve 1 having such a configuration will be described. As described above, when the needle 20 is lifted and the seat portion 21 is separated from the valve seat 16, the fuel in the fuel reservoir 15 is transferred to the valve seat 16. Is injected into the combustion chamber 6 through the flow path portion 17 and the injection hole 18.

Generally, in the case of a diesel engine, the maximum pressure of the combustion chamber 6 is about 6 MPa, and in the gasoline engine, the maximum pressure of the combustion chamber 6 is about 3 MPa. On the other hand, the fuel pressure supplied to the fuel injection valve 1 through the fuel injection pump 2 is 100MP in the case of a diesel engine.
It is about a and about 10 MPa for a gasoline engine.

Therefore, when the needle 20 separates from the valve seat 16, the fuel in the fuel reservoir 15 flows vigorously toward the injection hole 18. At this time, the valve seat 16 has a conical surface, whereas the flow path portion 17 has a substantially cylindrical surface, and the injection hole 18 has a narrowed diameter. Therefore, the flow passage area is rapidly expanded from the valve seat 16 to the flow passage portion 17, and the flow passage area is reduced from the flow passage portion 17 to the injection hole 18, and the flow direction is rapidly changed. . Therefore, the fuel flowing along the conical valve seat 16 separates from the conical surface as soon as it reaches the flow passage portion 17, so-called separation occurs, and the flow is disturbed to generate a vortex. Further, when the fuel flows from the flow path portion 17 into the injection hole 18, resistance is generated and a vortex flow is generated. In the flow path portion 17 where such a turbulent flow is generated, a portion having an extremely low fuel pressure is generated. This low pressure portion is connected to the air intake passages 19a-1
Since it is communicated with the combustion chamber 6 by 9d, the flow path portion 1
Air is automatically sucked into the combustion chamber 6 from the combustion chamber 6.

The air sucked from the air suction passages 19a to 19d rides on the vortex in the flow passage portion 17 and is mixed with the fuel, and the mixed fuel is injected into the combustion chamber 6 through the injection holes 18.

FIG. 3 shows the results of measurement of the pressure distribution in the flow passage section 17. FIG. 3 shows the pressure of each part measured by simulating the flow of fuel by making a 40 times model of the nozzle body 10, and measuring the pressure at points a to i shown in FIG. The results are shown in Fig. 3 (B).
As can be seen from FIG. 3B, the passage changes rapidly e
It can be confirmed that the pressures at the points and g are in the negative region.

Therefore, if one end of the air suction passages 19a to 19d is opened and the other end is opened to the combustion chamber 6 at the points e and g or in the vicinity thereof, the air of the combustion chamber 6 will be in the flow passage portion 17. Can be forcibly inhaled, and the flow path portion 1
It is possible to automatically mix the fuel and the air in 7.

When such a mixed fuel is injected into the combustion chamber 6, the resistance of the mixed air causes the fuel to be finely pulverized, and the atomization angle of the atomized fuel spreads. That is, FIG. 4 schematically shows the spray form in the conventional case and the spray form in the case of the present embodiment. FIG. 4 (A) shows a spray form using a conventional fuel injection valve, in which a liquid column part (a) of fuel is formed in the center part, and a large particle group is formed around the liquid column part (a) and in the tip part of the spray. There is B, and there are atomized particle groups c around. Moreover, the spread angle of the spray is small. On the other hand, FIG. 4B shows a spray mode using the fuel injection valve of this embodiment, in which the spray spread angle is extremely large, and the spray is occupied by the atomized particle groups c. Has been.

As a result, when the fuel injection valve of the present embodiment is used, atomization of the fuel is promoted, and moreover, it is diffused and sprayed, so that the ignitability of the fuel is improved, good combustion becomes possible, and noise It is effective in reducing fuel consumption, reducing harmful components in exhaust gas, and improving fuel efficiency.

Moreover, according to the present embodiment, since the air is automatically sucked, no special auxiliary equipment such as a supercharger or a pump is required, and no parts such as pipes are needed. In addition to being small in number, it can be easily mounted on a vehicle and can be provided at low cost.

The present invention is not limited to the structure of the first embodiment. That is, the injection hole 18 shown in FIG. 1 is a single injection hole, but in the second and third embodiments shown in FIGS. 5 and 6, the injection holes 18 are two or more in number. The air intake holes 19 ... May be opened only at the points e and g shown in FIG.

Further, the injection hole may be a throttle type injection hole 18 as in the fourth embodiment shown in FIG. Further, the air suction holes 19 ...
7 may be opened eccentrically with respect to the center of the flow path portion as in the fifth embodiment shown in FIG. 8. In this example, the air suction holes 19 ... This is the case when the flow path portion 1 is formed.
A swirling flow is generated within 7, and the mixing and stirring action with the fuel is improved, which is more effective for atomization. Further, the injection valve of the present invention is not limited to the fuel injection valve that is opened by the fuel pressure, but may be an electromagnetic fuel injection valve.

[0028]

As described above, according to the present invention, when the fuel is injected into the external space through the injection holes, the air is automatically sucked from the external space, and thus the flow path portion is provided. At, the fuel and air are mixed and the mixed fuel is injected through the injection hole. For this reason,
Since the fuel spray is atomized and diffused, the fuel ignitability is improved, good combustion is possible, and it is effective in reducing noise, reducing harmful components in exhaust gas, and improving fuel efficiency. . Moreover, according to the present invention, since the low-pressure portion generated in the flow passage automatically sucks in air, no special auxiliary equipment such as a supercharger or pump is required, and parts such as pipes are not required. Therefore, there are advantages that not only the number of parts is small, but also the mountability on a vehicle is excellent, and it can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention and enlarging a tip portion of a fuel injection valve.

FIG. 2 is a configuration diagram showing an entire fuel injection system using the fuel injection valve of the embodiment.

3A and 3B are diagrams in which the pressure at each point of the nozzle body is measured, where FIG. 3A is a diagram showing the measurement points, and FIG.

FIG. 4 is a view showing a spray form, FIG. 4A is a view of a spray form of a conventional fuel injection valve, and FIG.

FIG. 5 is a sectional view showing the second embodiment of the present invention and enlarging the tip portion of the fuel injection valve.

FIG. 6 is a cross-sectional view showing the third embodiment of the present invention and enlarging the tip portion of the fuel injection valve.

FIG. 7 is a sectional view showing a fourth embodiment of the present invention and enlarging a tip portion of a fuel injection valve.

FIG. 8 is a cross-sectional view showing a fifth embodiment of the present invention and showing a communication relationship between a flow path portion and an air intake passage.

[Explanation of symbols]

1 ... Fuel injection valve 2 ... Fuel injection pump
6 ... Combustion chamber 10 ... Nozzle body 11 ... Nozzle holder 15 ... Fuel reservoir 16 ... Valve seat
17 ... Flow path part 18 ... Injection hole 19 ... Air intake passage 20 ... Needle 21 ... Seat part 25 ... Coil spring

Claims (1)

[Claims] 1. A nozzle body is provided with a valve seat, a flow passage portion continuous to the downstream side of the valve seat, and an injection hole opened at an end of the flow passage portion, and accommodates a needle, and a seat of the needle. In a fuel injection valve that injects fuel toward the space where the injection hole is opened through the injection hole when the part separates from the valve seat, the low pressure generating part of the flow path part communicates with the space. A fuel injection valve characterized by opening an air intake passage for introducing air from this space, mixing fuel and air in the flow path portion, and injecting the mixed fuel through the injection hole.