JPS6029662Y2 - Internal combustion engine mixture supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the prevention of fuel wall flow occurring on the inner wall of the intake passage of a fuel-injected internal combustion engine.

As a conventional example of a fuel injection type internal combustion engine, a so-called single point injection (SPI) type engine in which fuel is injected at one location in an intake passage is shown in FIG.

An air cleaner 3 is attached to the upper end of a throttle body 2 provided with an intake throttle valve 1, and a Karman type intake flow rate detection device 4 is interposed in a part of the air cleaner 3.

A fuel injection valve 5 that injects an amount of fuel according to the amount of intake air measured by the device 4 is installed in the intake passage 6 on the downstream side of the intake throttle valve 1, and injects fuel in a direction perpendicular to the intake flow. .

A fuel collision plate 7 is disposed opposite to this fuel injection, and reflects the injected fuel to atomize the fuel.

Furthermore, an auxiliary air introduction passage 8 is provided in the throttle body 2 to bypass the intake throttle valve 1, and the air introduced through the passage 8 is passed from the outlet 8a around the fuel injection valve 5 to the intake air downstream of the intake throttle valve. The fuel is injected into the passage 6 to further promote atomization of the fuel injected from the injection valve 5.

In this way, by promoting atomization of the injected fuel, the mixture of fuel and air is improved, the air-fuel mixture properties are improved, and the distribution of the air-fuel mixture of the SPI system is improved.

The above effect is particularly significant in a low load region where the opening of the intake throttle valve is small.

In addition, 9 in the figure is a needle valve for adjusting the opening area of the auxiliary air introduction passage 8 (Japanese Patent Application Laid-Open No. 12411-1989).
(See Publication No. 8).

However, even with such a mixture supply device for an internal combustion engine, some of the fuel particles that collide with the fuel collision plate 7 and are scattered, or the injection that is diffused by the action of the air passing through the auxiliary air introduction passage 8. It was not possible to prevent a portion of the fuel from adhering to the inner wall of the intake passage 6, accumulating it, and flowing down the inner peripheral surface of the intake passage 6 as a wall flow.

This kind of fuel wall flow intermittently flows into the cylinder or drops from a part of the inner wall of the intake passage and flows intermittently, causing variations in the air-fuel mixture ratio, impeding the stability of the engine, and reducing the exhaust gas flow. This resulted in a deterioration in performance.

In addition, electronically controlled fuel injection systems detect the mixture air-fuel ratio from the oxygen concentration in the exhaust gas and perform feedback control of the fuel injection amount, but due to the above-mentioned variations in the mixture air-fuel ratio, a delay in response occurs during excessive operation. .

In view of the above-mentioned disadvantages of the conventional device, the present invention improves the outlet of the auxiliary air introduction passage that bypasses the intake throttle valve, and creates an air curtain on the inner wall of the intake passage to prevent fuel from adhering to it. This also prevents raw fuel wall flow.

Embodiments of the present invention will be described below based on the drawings from FIG. 2 onwards.

In the following description, the same elements as in the conventional device are given the same reference numerals as in FIG. 1 to simplify the description.

In the embodiment shown in FIGS. 2 and 3, the auxiliary air introduction passage 8
Unlike the conventional example described above, the outlet is opened in the inner wall of the intake passage between the intake throttle valve 1 and the fuel injection valve 5.

That is, a substantially annular recess 11 is provided on the inner wall of the intake passage 6 upstream of the collision plate 7 over approximately the entire circumference (excluding the area immediately upstream of the fuel injection valve 5), and communicates with the auxiliary air introduction passage 8.

The recess 11 is covered by a cylindrical guide 12 that is press-fitted into the inner circumferential wall of the intake passage 6 and is flush with the inner surface of the upstream intake passage 6 .

The peripheral edge of the cylindrical guide 12 on the downstream side of the intake air is overlapped with the inner surface of the intake passage 6 near the downstream side of the recess 11 with a gap therebetween, thereby forming the outlet 13 of the annular recess 11 .

Therefore, the shape of the outlet 13 is a substantially ring-shaped slit, and its opening direction is directed toward the intake downstream side along the inner surface of the intake passage 6.

In the figure, a collecting part 15 of an intake manifold 14 is connected to the lower end of the throttle body 2 via an insulator 16, and a cylindrical extension 17 that is continuous with the intake passage 6 of the throttle body 2 is connected to the collecting part 15 of the intake manifold 14. It's going deep inside.

Reference numeral 19 denotes a control unit that receives a detection signal from an intake flow rate detection device or the like, detects the engine operating state, and controls the fuel injection amount of the fuel injection valve 5.

Therefore, according to the above configuration, in an idling or partial load operating region where suction negative pressure is developed on the downstream side of the intake throttle valve 1, the pressure difference between the suction negative pressure and the pressure on the upstream side of the throttle valve causes air to flow from the auxiliary air introduction passage 8. Air is introduced into the annular recess 11
After being stored in the air, the air is ejected into the intake passage 6 at high speed from the outlet 13 that forms a gap between the guide 12 and the inner wall of the intake passage 6.

Here, since the outlet 13 opens toward the intake downstream side along the inner surface of the intake passage 6, the air ejected from the outlet 13 forms an air curtain along the inner surface of the passage.

As a result, even if the injected fuel that collides with the collision plate 7 and is reflected and scatters tries to adhere to the inner surface of the intake passage 6, it is blocked by the air curtain, so that the fuel wall flow flowing down along the inner wall of the intake passage and from the extension 17 It is possible to prevent fuel from dripping.

This effect is particularly large in the above-mentioned operating range where the injected fuel spray spreads widely due to the high suction negative pressure and tends to adhere to the inner wall of the intake passage without colliding with the collision plate 7.

The reason why the outlet 13 of the auxiliary air introduction passage 8 is not provided immediately upstream of the fuel injection valve 5 is to prevent the injected fuel from being blown away by this air flow, so that the fuel collides well with the collision plate 7 and the fuel is removed. This is intended to promote atomization of the particles.

In the high load area where the suction negative pressure decreases, the auxiliary air introduction passage 8
Although the flow rate of air flowing through the fuel tank decreases relative to the total air flow rate, in this operating range, the intake air flow is fast and the injected fuel is atomized well, so there is less risk of wall flow and there is no problem.

In the above embodiment, the outlet 13 of the auxiliary air introduction passage 8
Although the air curtain is provided in an annular shape around almost the entire circumference, if the air curtain is created concentratedly on the inner circumferential wall of the intake passage where wall flow is likely to occur, the air curtain can be reduced during idling and partial load when the amount of intake air is limited. This strengthens the wall flow and increases its effectiveness in preventing wall flow.

FIG. 4 shows an embodiment that takes this point into consideration.

That is, after the injected fuel collides with the collision plate 7, it is often scattered on both sides of the collision plate 7 in parallel with it, as shown in the figure.

Therefore, in this embodiment, the outlet 13A of the auxiliary air introduction passage 8,
13B is formed into a slit shape of a predetermined length and is formed in two places on the inner wall of the intake passage on both sides of the collision plate 7.

In addition, the embodiment shown in FIG. 5 has an outlet 13 of the auxiliary air introduction passage 8 in addition to the embodiment shown in FIG. The aim is to simultaneously promote atomization.

In this way, the mixing of fuel and air is improved or the number of large diameter fuel droplets penetrating the air curtain is reduced, further improving the effectiveness of the air curtain.

Although the above embodiment has been described with respect to the case of horizontal injection-gPI, it is also possible to similarly implement the case where fuel is injected within a carburetor or a throttle body.

Furthermore, it is effective to form this air curtain on the inner wall of the intake passage near the fuel injection valve, but even if it is formed on the inner wall of the intake passage other than that, the fuel wall flow will be blocked at the jetting part of the air curtain, and the air-fuel mixture will be Needless to say, it is possible to prevent fuel droplets from adhering inside.

As described above, according to the present invention, the outlet of the auxiliary air introduction passage that bypasses the intake side valve is formed in the shape of a slit having a predetermined length in the circumferential direction of the intake passage, and the outlet is formed in the shape of a slit having a predetermined length in the circumferential direction of the intake passage. Since the intake passage is open in both directions, an air curtain can be formed along the inner surface of the intake passage.

For this reason, it is possible to prevent the fuel injected from the injection valve from adhering to the inner wall of the intake passage, thereby preventing fuel wall flow, or blocking and blowing off the fuel wall flow that has formed in the upstream, thereby preventing wall flow or dripping. It is possible to reduce fluctuations in the air-fuel ratio of the mixture due to

As a result, engine stability and exhaust performance are improved, and response delay in fuel supply control can be improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a conventional mixture supply device, and FIG. 2 is a vertical sectional view showing an embodiment of the mixture supply device according to the present invention.
Fig. 3 is a sectional view taken along line A-A of the same as above, Fig. 4 shows another embodiment of the present invention, and is a view corresponding to the section B-B of Fig. 3, and Fig. 5 shows a third embodiment of the invention. FIG. 1... Intake throttle valve, 5... Fuel injection valve, 6... Intake passage, 7... Fuel collision plate, End... Auxiliary Air introduction passage, 11... recess, 12... cylindrical guide, 13.13A, 1
3B, 13C...Exit.

Claims (1)

[Claims for Utility Model Registration] 1. In an internal combustion engine in which fuel is injected into the intake passage from a fuel injection valve, the outlet of the auxiliary air introduction passage that bypasses the intake throttle valve is formed into a slit shape having a predetermined length in the circumferential direction of the intake passage. 1. An air-fuel mixture supply device for an internal combustion engine, characterized in that the air-fuel mixture is formed at a downstream side of an intake passage along an inner circumferential wall of an intake passage and is opened at a position upstream of the fuel injection valve. 2. The outlet of the auxiliary air introduction passage connects the intake downstream end side peripheral edge of the cylindrical guide fitted in the intake passage to the intake passage inner peripheral surface near the lower part of the recess so as to cover the recess formed in the intake passage inner peripheral wall. The air-fuel mixture supply device for an internal combustion engine according to claim 1, which is formed by overlapping the two with a gap serving as the outlet therebetween. 3. Utility model registration claim No. 3, characterized in that the outlet of the auxiliary air introduction passage is formed in an annular shape over substantially the entire inner circumference of the intake passage, or by providing l or a plurality of slits of a predetermined length at predetermined positions. A mixture supply device for an internal combustion engine according to item 1 or 2. 4 Utility model registration claims 1 to 3 in which a part of the outlet of the auxiliary air introduction passage is opened around the fuel injection valve
2. A mixture supply device for an internal combustion engine according to any one of paragraphs.