JPH04153568A - Fuel injector - Google Patents

Abstract

PURPOSE:To uniformly and finely mix fuel with air by forming the outer shape of a fuel injection passage boss to an expanded inclined part whose outside diameter part gradually spreads toward the downstream side along the axis line Y-Y in the longitudinal direction of the fuel injection passage. CONSTITUTION:An expanded inclined part 6C whose inside diameter gradually spreads toward an opened port edge part 6B on the downstream side from an expansion starting point A of a fuel injection passage 6 is formed, and the inside diameter is spread continuously along the axis center line Y-Y in the longitudinal direction of the fuel injection passage 6. In the fuel injection passage 6, a cone member 9 forming an annular gap together with the inside diameter of the fuel injection passage 6 is arranged. The outer shape of a fuel injection passage boss 10 on which the fuel injection passage 6 is drilled is formed so a to have the expanded inclined part 10A whose outside diameter part gradually spreads towards the downstream side along the axis center line Y-Y in the longitudinal direction of the fuel injection passage 6. Accordingly, in all the operation regions from ranging the low speed operation to the high speed operation of an engine, the fuel containing air which is jetted into an intake passage from the opened port edge part of the fuel injection passage is allowed to directly collide with the cone member, and can be finely dispersed into an annular gap.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fuel injection device that injects fuel pressurized by a fuel pump into an intake passage through a fuel injection valve, and particularly relates to a fuel injection device that injects fuel pressurized by a fuel pump into an intake passage through a fuel injection valve. Fuel in the so-called single point injection method (hereinafter referred to as the SPI method), in which fuel is injected from a single fuel injection valve toward the intake path on the downstream side, and this fuel is supplied to the intake pipes connected to each cylinder of the engine. This relates to an injection device.

[Conventional technology]

JP-A-53-7 as a fuel injection system H in the SPI system
There is No. 2923. The main purpose of this is to discharge fuel uniformly into the intake passage and to evenly supply fine fuel to each intake pipe connected to each cylinder.
an internal air chamber located upstream of the throttle valve that controls air passing through the throttle valve to receive air from the throttle valve's main air passage and to receive fuel injected by a fuel injector at right angles to the inner surface; a circular fuel swirl chamber forming a fuel ring therein, an orifice restricting air flow through the atomizer, and an outlet port returning the vaporized mixture to the main air passage downstream of the throttle valve; It has been established.

Thus, fuel injected by the fuel injection valve in response to actuation by the electronic controller enters the groove at a relatively high velocity and forms a fuel ring within the groove. The circular motion of the fuel within the groove spreads the fuel in a thin film on the inner surface of the groove. This film of fuel is gradually carried away by the air stream exiting the orifice, breaking it into smaller particles than can be obtained with conventional atomizers.

Also, the residence time of the fuel inside the groove significantly increases the fuel supply time.

[Problem to be solved by the invention]

This conventional fuel injection device has the following problems to be solved.

~1. This is because fuel is injected eccentrically from a fuel injection valve in the tangential direction of the groove, creating a vortex within the groove to form a thin film-like fuel ring on the inner surface of the groove, and this fuel ring is gradually carried away by air. , ■When the spray angle of the fuel injected into the groove from the fuel injection valve changes (the spray angle of the fuel injection valve is generally between 10° and 40°), it forms on the inner surface of the groove. Even if the amount of air supplied from the orifice into the groove is constant, the amount of fuel carried by the air from the outlet boat into the main air passage may change as the thin film vortex of the fuel changes (thin film). (This is due to changes in the vortex state) which is unfavorable in terms of uniform fuel supply.

However, if the discharge pressure of the fuel pump that supplies pressurized fuel to the fuel injection valve changes, the pressure of the fuel injected from the fuel injection valve into the groove changes, and this causes the fuel to be formed on the inner surface of the groove. The thin film vortex state of the fuel changes, resulting in the same problem as in (2) above.

■The injection energy of the fuel injected into the premises is used to create a vortex on the inner peripheral surface of the groove, and does not actively affect the mixing with the air supplied from the air passage. The film of fuel that forms on the inner surface is gradually carried away by the air flow exiting the orifice. Therefore,
The fuel and air are not actively mixed finely within the groove.

(2) When the engine suddenly decelerates, an extremely large intake negative pressure is generated in the intake passage downstream of the throttle valve, and this intake negative pressure acts on the entire interior of the groove via the outlet.

Therefore, this intake negative pressure also acts on the fuel surface of the thin-film fuel ring formed on the circumferential surface of the groove, and there is a risk that the fuel may be peeled off toward the inside of the groove. This causes disturbances in the fuel mixture in the vicinity. In other words, the distribution of fuel near the outlet of the groove becomes uneven, which prevents uniform fuel supply.

■Fuel injected from the fuel injection valve is injected into a groove with a relatively large chamber volume and forms a fuel ring on the inner surface of the groove, but the flow velocity of the fuel ring on the inner surface of this groove decreases as it goes downward. However, there is a possibility that this fuel may scatter (sag) inward of the groove, resulting in a worsening of the fuel mixing condition near the outlet of the groove.

■The injection shape of the discharged fuel injected from the fuel injection valve is a flare shape in which the fuel diffuses, and a pencil beam shape in which the fuel converges. In order to form a vortex flow in w, it is desirable for the fuel to move circularly at a relatively high speed on the inner surface of the groove, and for this purpose, a fuel injection valve having a pencil beam injection shape is preferable.

In the flared shape, fuel diffuses into the groove and is less likely to generate swirl on the inner surface of the groove.

Therefore, the injection shape of the fuel injection valve is easily limited.

~2. As shown in Figures 3 and 4 of JP-A-53-72923, an orifice is provided between the groove and the outlet, and the air supplied from the air passage and the inner surface of the groove are Mixing with the thin film of fuel flowing through the air is carried out in a groove with a relatively large volume upstream of the orifice, and when supplied to the intake passage, this air-fuel mixture is throttled again at the orifice, so that the fuel is converged by the orifice. This is not preferable in terms of fuel atomization.

[Means to solve problems]

The fuel injection device of the present invention was created in view of the above-mentioned problems, and aims to provide a fuel injection device with excellent fuel atomization characteristics and uniformity in the SPI method, and to achieve the above-mentioned purpose. In a fuel injection device for an internal combustion engine that supplies fuel injected from a fuel injection valve to the engine via an intake passage downstream of a throttle valve, a Approximately parallel to the longitudinal axis x-x, the upstream side is closed and the downstream side is open, and the downstream opening has an inner diameter portion that gradually expands toward the downstream side of the intake path. A fuel injection passage provided with an enlarged slope: An injection valve injection passage that opens into the fuel injection passage for injecting and supplying fuel injected from the fuel injection valve into the fuel injection passage; One end is connected to the atmosphere or a throttle valve. Opens in the intake path on the more upstream side,
an air passage whose other end opens into the injector injection path; an annular air passage disposed at least within the enlarged slope of the fuel injection path and continuous along the longitudinal axis Y-Y of the fuel injection path together with the expansion slope; The outer shape of the fuel injection passage boss is composed of a cone member having an enlarged inclined protrusion forming a gap, and is located in the intake passage on the downstream side of the throttle valve and has the fuel injection passage bored in the center thereof. Longitudinal axis of fuel injection path Y-Y
This is an expanding sloped portion whose outer diameter portion gradually expands toward the downstream side along the slope.

[Effect]

According to the fuel injection device configured as described above, the fuel injected from the fuel injection valve is injected toward the cone member in the fuel injection path via the injection valve injection path. Atmospheric air or air in the intake passage upstream of the throttle valve flows into the fuel flowing through the air passage, and the fuel and air mix in the injection passage of the injection valve, and the fuel containing this air is injected by the injection valve. The fuel is injected from the fuel injection path toward the cone member within the fuel injection path.

The air-containing fuel that has collided with the cone member is dispersed at a high injection speed into the annular gap formed between the enlarged inclined part of the fuel injection path and the enlarged inclined protrusion of the cone member, and is dispersed into the annular gap. The fuel containing air flows down toward the outlet of the fuel injection passage, and is injected into the intake passage from the outlet on the downstream side of the fuel injection passage.

The annular gap is formed with a relatively small gait ff1 (small gap), and the flow rate of the fuel containing air does not decrease. By being formed continuously towards
A reliable annular fuel form can be formed, and the annularly formed fuel containing air can be injected while expanding from the end of the fuel injection path toward the inner surface of the intake path.

On the other hand, in the outer diameter portion of the fuel injection passage boss, the air flowing down in the intake passage flows down along the outer shape of the fuel injection passage boss. Air flowing through the outer shape of the boss expands and flows from the lower end of the fuel injection passage boss toward the inner wall surface of the intake passage.

The annular fuel injected from the fuel injection passage toward the inner wall of the intake passage mixes with the air flowing from the outer part of the fuel injection passage boss toward the inner wall of the intake passage, and the flow is directed toward the inner wall of the intake passage. It is oriented further toward the wall surface, and the fuel and air can be mixed more finely and uniformly in the portion where the air flow rate is high.

〔Example〕

Hereinafter, one embodiment of a fuel injection device according to the present invention will be described with reference to FIG.

Reference numeral 1 denotes a throttle valve body through which an intake passage B extends from the top to the bottom in FIG. A throttle valve 3 is arranged, and the opening and closing of the intake passage B is controlled by this throttle valve 3.

Reference numeral 4 denotes an injection valve body disposed below the throttle valve body 1, and an intake passage B passes through this injection valve body 4 from the top to the bottom, connecting the throttle valve body 1 and the injection valve body. 4
By connecting these, an intake passage B is formed that vertically penetrates each main body 1, 4.

5 is ECU (Electronic Control)
When a current flows through the solenoid coil in response to a signal from Unit E, the core is sucked until the flange of the needle pulp that is integrated with the core hits the Nupesa, the valve is fully opened, and the fuel pump is applied. This is a known fuel injection valve that injects pressurized fuel from its tip. (Description of the internal structure of the fuel injection valve will be omitted.

) 6 is a fuel injection path provided in the injection valve body 4 and is configured as follows. That is, the fuel injection path 6 has a circular cross section, is located in the intake path B downstream from the throttle valve 3 (lower side on the engine side in FIG. 1), and is located within the intake path B.
The longitudinal axis Y-Y of the intake passage B is the longitudinal axis x
-x, its upstream side is closed by a closed end 6A, and its downstream side opens into the intake path B via an open end 6B.

Then, the inner diameter of the fuel injection passage 6 gradually expands toward the opening end 6B on the downstream side from the expansion starting point A (between the closed end 6A and the open end 6B of the fuel injection passage 6). A sloped portion 6C is provided. The enlarged inclined portion 6C has an inner diameter that continuously expands along the longitudinal axis Y-Y of the fuel injection passage 6, and whether the inclination is linear or curved, there is no step. However, the inner diameter must be expanded and not reduced (funnel-like).

FIG. 1 shows a linear enlarged inclined portion 6C.

Reference numeral 7 denotes an injection valve injection passage for injecting fuel injected from the fuel injection valve 5 into the fuel injection passage 6, one end of the injection valve injection passage 7 is connected to the nozzle portion of the fuel injection valve 5, and the other end is connected to the nozzle portion of the fuel injection valve 5. opens into the fuel injection passage 6. The longitudinal axis Z-Z of the injector injection passage 7 opens toward the longitudinal axis Y-Y of the fuel injection passage 6, and in this example, the fuel injection passage 6 upstream from the expansion starting point A Open to. (Furthermore, the fuel injection valve 5 may be arranged in the throttle valve main body l.) One end of the fuel injection valve 8 opens into the intake passage B on the upstream side of the throttle valve 3, and the other end opens into the injection passage 7 of the injection valve. It is an open air passage,
One end of this air passage 8 may be opened to the atmosphere.

A cone member 9 is disposed within the fuel injection passage 6 and forms an annular gap with the inner diameter of the fuel injection passage 6.

This cone member 9 is disposed within an enlarged inclined portion 6C of the fuel injection passage 6, and includes an enlarged inclined protrusion 9A having a continuous enlarged portion toward the downstream side and an enlarged inclined protrusion 9A in the fuel injection passage 6D upstream from an enlarged starting point A. The cylindrical portion 9B of the cone member 9, the fuel injection path 6D on the upstream side of the expansion starting point A of the fuel injection path 6, and the expansion inclination of the fuel injection path 6. The portion 6C and the enlarged inclined protrusion 9A of the cone member 9 form an annular gap extending downward from above.

Thus, at the open end 6B of the fuel injection passage 6, an annular gap opens toward the intake passage B on the downstream side. The annular gap is preferably about one layer thick, but is not limited to this value and can be set as appropriate.

The fuel injection passage 6 is bored in the fuel injection passage boss lo, and the fuel injection passage boss 10 is located along the longitudinal axis of the intake passage B in the intake passage B on the downstream side of the throttle valve 3. placed on x-x.

The outer shape of the fuel injection path post 10 is the same as that of the fuel injection path 6.
Longitudinal axis of &! It has an enlarged inclined portion 1OA whose outer diameter portion gradually enlarges toward the lower yt side along YY. That is, the outer diameter of the fuel injection path post lO outside the open end 6B of the fuel injection path 6 is larger than the outer diameter of the other (upstream) fuel injection path post lO.

In this example, the upstream portion thereof forms a cylinder, and an enlarged inclined portion 10A is formed downstream from the middle portion of the cylinder.

Incidentally, as shown by a dashed line in FIG. 1, an enlarged inclined portion 10A may be provided continuously from upstream to downstream of the outer diameter portion of the fuel injection path post 10.

Further, the enlarged inclined portion 10A may be linear, curved, or stepped.

Numeral 11 is a fuel passage connected to a fuel pump (not shown), and the fuel injection valve 5 receives fuel from this fuel passage 11.

Next, its effect will be explained.

When the engine is operating, the intake path B downstream of the throttle valve 3
Air controlled by the throttle valve 3 and air passing through the air passage 8 flow inside, while fuel controlled by the fuel injection valve 5 is injected from the fuel injection passage 6 toward the intake passage B. be done.

Here, we will look at the behavior of the air and fuel flowing through the fuel injection path 6. Fuel injected from the fuel injection valve 5 in response to an output signal from the ECUE is injected into the fuel injection path 6D upstream of the expansion starting point A via the injection valve injection path 7. In the air passage 8, an opening 8B at one end opens into the atmosphere or into the intake passage B upstream from the throttle valve 3, and an opening 8A at the other end.
is opened in the injection valve injection path 7, and on the other hand, the injection valve injection path 7 is pressurized to a high pressure (for example, 2.55 kg/c rn') by a fuel pump (not shown) as described above. As fuel is discharged and flows through the fuel injection valve 5, a negative pressure is generated in the opening 8A at the other end of the air passage 8 that opens into the injection valve injection path 7 due to the high-pressure fuel flow. and the pressure at the opening 8A at the other end of the air passage 8 is
Since the pressure is lower than that of B, air flows down from the opening 8B at one end of the air passage 8 toward the opening 8A at the other end, and this air is drawn into the fuel flowing inside the injection valve injection path 7. and mix.

Thus, fuel mixed with air (fuel containing air) is injected into the fuel injection path 6D upstream of the expansion starting point A via the injection valve injection path 7. The air-containing fuel injected into the fuel injection path 6D collides with the cylindrical portion 9B of the cone member 9 at a high speed, and the air-containing fuel is finely scattered by this collision and is dispersed into one cylindrical portion 9B. It is finely dispersed over the entire outer circumference. This is because a small annular gap is formed between the fuel injection path 6D upstream of the expansion starting point A and the cylindrical portion 9B of the cone member 9 (maintained at a small volume), and the injection contains air. This is achieved by not reducing the velocity of the fuel.

The fuel containing finely dispersed air having a high velocity within the annular gap between the cylindrical portion 9B of the cone member 9 and the fuel injection path 6D on the upstream side of the expansion starting point A is transported to the cone member 9. The fuel is injected into the annular gap formed by the enlarged inclined protrusion 9A and the enlarged inclined part 6C of the fuel injection path 6, and flows down along the inclined annular gap while being evenly distributed within this annular gap. .

This is because the annular gap is so small that it is possible to suppress the drop in the wave speed of the fuel containing dispersed air, and the slanted annular gap is arranged along the longitudinal axis Y-Y of the fuel injection path 6. This is achieved by forming them continuously and regulating the direction of fuel flow at a certain distance.

Then, the fuel mixed with the air is injected into the intake passage B through an annular gap formed at the open end 6B of the fuel injection passage 6 in a completely annular spray shape that is evenly distributed.

In order to supply even fuel to each cylinder that makes up the engine, it is necessary to have symmetry at least in the intake passage of the fuel injection device and to supply fine and uniform fuel. . When the engine is operated at high speed when the throttle valve 3 is opened to a high opening degree, the amount of fuel consumed by the engine is large, so the amount of fuel injected from the fuel injection valve 5 toward the fuel injection path 6 is large. be. When this large amount of air-containing fuel is injected into the minute annular gap formed by the fuel injection path 6 and the cone member 9, the speed of the air-containing fuel flowing through this gap is weakened. The fuel containing finely divided and uniformly dispersed air within the annular gap is injected into the intake passage B in a perfect annular injection shape that follows the annular gap and maintains symmetry.

On the other hand, when the engine is operated at low or medium speeds with the throttle valve 3 opened to a low or medium opening degree, the amount of fuel consumed by the engine is smaller than that during high-speed operation, and the fuel injection path is The amount of fuel injected into 6 will be small.

However, in the injection valve injection path 7, the injection valve injection path 7
Air flows into the air passage 8 due to the negative pressure generated by the fuel flowing through the injector, mixes with the fuel flowing through the injection valve injection passage 7, and the fuel mixed with this air is injected into the fuel injection passage 6. in.

The capacity of the fuel mixed with air within the annular gap of the fuel injection passage 6 is not significantly reduced.
Although the amount of fuel supplied into the fuel injection path 6 is small, the volume of the fuel mixed with air is not reduced so much that the flow rate of the fuel containing air flowing through the annular gap of the fuel injection path 6 is maintained in a high state. The fuel does not adhere to the walls of the annular gap, the fuel and air are mixed well, and the air is finely and uniformly dispersed within the annular gap. The fuel flows into the intake passage B with a perfect annular injection shape that has symmetry following the annular gap.
Injected inside.

In this way, the annular fuel injected into the intake passage B is uniformly and well mixed with the air flowing inside the intake passage B. This is because the fuel injected from the open end 6B of the fuel injection path 6 forms a completely annular spray shape as described above, and is expanded from the open end 6B and injected toward the inner wall of the intake path B. Things.

The airflow flowing down along the outer diameter of the fuel injection path pos 10 is annular from the downstream end of the fuel injection path pos 10 toward the inner wall of the intake path B along the enlarged inclined portion 10A of the fuel injection path pos 10. The fuel injected from the fuel injection passage 6 is caused to expand and flow further toward the inner wall of the intake passage B in an annular manner by the air flowing around the outer diameter of the fuel injection passage post 10. by.

That is, the fastest part of the air flow undulating in the intake passage B is the part relatively close to the inner wall of the intake passage B, and the air-containing fuel injected from the open end 6B of the fuel injection passage 6 reaches this flow velocity. This is because the annular fuel is uniformly injected toward the fast airflow, and the fuel is well mixed with the air flowing through the intake passage B.

By being able to inject symmetrical and uniform fuel into the intake passage B, uniform fuel can be supplied to each intake pipe connected to each cylinder of the engine, which improves the engine's output.
This resulted in significant improvements in engine performance, including stable rotation.

Moreover, the opening end 6B of the fuel injection passage 6 is connected to the intake passage B on the engine side.
If the positive pressure part of the pulsating pressure generated during engine operation acts on the annular gap from the open end 6B, the upper part of the fuel injection path 6 will open toward the closed end 6A. Since high-pressure fuel is injected into the fuel injection passage 6 into the injection valve injection passage 7 which is closed and opens into the fuel injection passage 6, even if such positive pressure is received, the fuel injection passage 6
The fuel injected into the injector does not flow back into the injection path 7 and the air passage 8, and all the fuel injected into the fuel injection path 6 flows into the intake path B from the open end 6B without any time delay. Since the fuel is injected and supplied at high pressure, it is possible to prevent variations in the air-fuel mixture in each cylinder and to suppress delays in fuel discharge, thereby making it possible to stabilize rotation and improve acceleration response.

Moreover, when the opening of the injector injection path 7 to the fuel injection path 6 is opened toward the enlarged inclined portion 6C of the fuel injection path 6, the cylindrical portion 9B of the cone member 9 and the enlarged starting point A of the fuel injection path 6 are upstream. There is no particular need to provide an annular gap formed by the side fuel injection passage 6D.

〔Effect of the invention〕

As described above, the fuel injection device according to the present invention provides the following special effects.

In a fuel injection device for an internal combustion engine that supplies fuel injected from a fuel injection valve to the engine via an intake passage downstream of a throttle valve, the fuel injection device is located within the intake passage downstream of the throttle valve and extends in the longitudinal direction of the intake passage. It is substantially parallel to the axis x-x, and its upstream side is closed and its downstream side is open, and the downstream opening has an expanding slope whose inner diameter gradually expands toward the downstream side of the intake path. a fuel injection passage having a section; an injection valve injection passage opening into the fuel injection passage for injecting and supplying fuel injected from the fuel injection valve into the fuel injection passage; one end of which is connected to the atmosphere or upstream of the throttle valve; Opens into the side intake passage,
an air passage whose other end opens into the injector injection path; an annular air passage disposed at least within the enlarged slope of the fuel injection path and continuous along the longitudinal axis Y-Y of the fuel injection path together with the expansion slope; The outer shape of the fuel injection passage boss is made of a cone member having an enlarged inclined protrusion that forms a gap, and is located in the intake passage on the downstream side of the throttle valve, and has the fuel injection passage bored in the center. Longitudinal axis of fuel injection path Y-Y
Since the expanding inclined part is formed so that the outer diameter part gradually expands toward the downstream side along the Due to the gap formed by the fuel injection valve, the flow velocity of the fuel containing air injected from the fuel injection valve does not decrease in the entire operating range, from low-speed operation of the engine with a small fuel flow rate to high-speed operation with a large fuel flow rate. The fuel can be finely dispersed within the annular gap by directly impinging on the cone member, and the continuously formed annular gap forces the fuel to contain air into an annular shape, allowing the throttle valve to open at a low opening. From to a high opening degree, it is possible to inject and supply fuel containing uniform and fine perfect annular air toward the inner wall of the intake passage, and only the injection valve injection passage is open to the fuel injection passage. Since the air passage is not open, even if a positive pressure portion of the pulsating pressure generated in the intake passage acts on the fuel injection passage, the fuel will not flow back into the air passage. The air-containing fuel that is injected from the end of the fuel injection passage toward the intake passage is mixed with the air that expands and flows toward the inner wall of the intake passage by the expanding slope of the outer diameter of the fuel injection passage boss. Since this fuel mixes with the fast-flowing air flowing near the inner wall of the intake passage, it is possible to supply uniform and finely dispersed fuel to the engine, which improves the engine's output and speed, especially when using an SPI fuel injection system. This has an extremely large effect on improving the stability of.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a main part showing an embodiment of a fuel injection device according to the present invention. 1. Throttle valve body 3. Throttle valve 4
, Injector main body 5 , Fuel injection valve 6 , Fuel injection path 6B, Open end 6C, Enlarged inclined portion 7, Injector injection path 8, , Air passage 9 , Cone member 9A, Enlarged inclined protrusion 10 , Fuel injection path boss 10 A, Enlarged inclined portion

Claims (1)

[Scope of Claims] A fuel injection device for an internal combustion engine that supplies fuel injected from a fuel injection valve to the engine via an intake passage downstream of a throttle valve, comprising: , is approximately parallel to the longitudinal axis X-X of the intake passage, its upstream side is closed and its downstream side is open, and the downstream opening has an inner diameter portion extending toward the downstream side of the intake passage. a fuel injection passage provided with an enlarged slope that gradually expands; an injection valve injection passage opening into the fuel injection passage for injecting and supplying fuel injected from the fuel injection valve into the fuel injection passage; Opens into the atmosphere or into the intake passage upstream of the throttle valve,
an air passage whose other end opens into the injector injection path; an annular air passage disposed at least within the enlarged slope of the fuel injection path and continuous along the longitudinal axis Y-Y of the fuel injection path together with the expansion slope; a cone member having an enlarged inclined protrusion that forms a gap; , the longitudinal axis of the fuel injection path Y-Y
A fuel injection device that forms an expanding sloped portion whose outer diameter portion gradually expands toward the downstream side.