JPS581653Y2 - Fuel supply system for multi-cylinder internal combustion engine - Google Patents

Description

[Detailed description of the invention] The present invention is a fuel supply system for a multi-cylinder internal combustion engine, in particular, one fuel injection valve is provided in the intake passage downstream of the throttle valve and upstream of the riser part, and all cylinders are supplied from this one injection valve. This invention relates to an improvement in a single point injection type fuel supply device that supplies fuel.

The structure of a generally adopted single point injection type fuel supply system is explained with reference to FIG.
It consists of a plurality of branch parts 3 and a collector part 4 in which these veranti parts 3 are assembled, and the bottom part of the collector part 4 is a riser stove part 6 which is adjacent to an exhaust manifold 5 and heats intake air.

An intake passage 8 equipped with a throttle valve 7 is connected to the upstream side of the collector portion 4, and a fuel injection valve 9 is connected to the fuel injection valve 9 through a bracket member 8a downstream of the throttle valve 7 in the intake passage 8 so that the direction of fuel injection is determined by the intake air flow. It is installed so that it intersects with the

In such a fuel supply system, a part of the injected fuel collides with and adheres to the inner wall of the opposite intake passage on the opposite side of the fuel injection valve, and this becomes a wall flow that travels along the inner wall, causing intake swirl. Since the fuel is easily guided to a specific branch portion along the flow, the fuel distribution between the cylinders is poor and the air-fuel mixture concentration is highly uneven between the cylinders.

In addition, when using a lean mixture for the purpose of reducing NOx emissions, there are even stricter requirements for fuel atomization and improved mixing properties. It became difficult to accelerate the engine, which was disadvantageous in terms of exhaust gas and fuel efficiency measures, and reduced engine performance.

In particular, when the engine is idling, the amount of intake air is small, so an improvement in the mixing properties of air and fuel would have been expected.

The present invention addresses the shortcomings of the conventional single-point injection type fuel supply system, and includes:
A pair of air nozzles are used to direct the intake air flow parallel to the intake air flow from above and below both sides toward the boundary point where the liquid film flow of the fuel injected from the fuel injection valve is about to scatter as droplets. Air is injected in a direction perpendicular to the fuel injection axis, which promotes atomization of fuel and improves mixing with intake air and distribution of fuel supply between each cylinder, improving engine operating performance and exhaust performance. The present invention provides a fuel supply device that achieves improvements.

The embodiment will be described below based on FIGS. 2 to 4.

In the embodiment, the same components as in FIG. 1 are given the same reference numerals to avoid duplication of explanation.

Referring to FIG. 2, the air nozzle constituting the present invention is formed as follows.

One inlet port 12 and one
A passageway 15 is formed with a pair of outlet ports N3.14.

A pipe member 16 is connected to the inlet port 12 of the passage 15.
The pipe member 16 and the opening end 17a cut off at an acute angle are connected to the intake passage 8 upstream of the throttle valve 7.
The pipe member 17 is connected to the pipe member 17 through a tube 18.

Curved nozzles 19 and 20 are connected to the pair of outlet ports 13 and 14, respectively, and a nozzle hole 19 is opened at the tip of each nozzle.
a.

20a (for example, about 1φ to 1.5φ) is oriented within a plane that includes the central injection axis l of the fuel injection valve 9 and is parallel to the flow direction of intake air, and is sandwiched at right angles to the central injection axis l, for example, They are arranged to face each other with an interval of about 7 to 8 IIX211.

As a result, the intake passage 8 upstream and downstream of the throttle valve 7 is
A bypass intake passage 10 is formed which bypasses and connects the two.

In the fuel supply device equipped with the air nozzle configured as described above, during engine operation, air on the upstream side of the throttle valve 7 is drawn into the bypass intake from the opening end 17a due to the differential pressure on the downstream side of the throttle valve 7 in the intake passage 8. Nozzle holes 19a, 2 introduced into the passage 10
Two colliding air streams facing each other are emitted from 0a.

These nozzle holes 19a because the collided airflow diffuses all radially in a plane orthogonal to the intake airflow that has passed through the throttle valve 7.

Fuel injected from the injection valve 9 so as to pass through the gaps 21a is spread and spread within the above-mentioned plane, promoting atomization of the fuel.

(At this time, the injection state seen from the direction of the intake air flow is like a fan-shaped diffuser as shown in FIG. 3A.

FIG. 3B is viewed from the same direction as FIG. 2.

) Furthermore, since the direction of diffusion of the fuel is perpendicular to the flow direction of the intake air, the diffused fuel is effectively mixed with the intake air, thereby increasing the uniformity of the mixture concentration.

In this way, the air-fuel mixture whose concentration has already been sufficiently homogenized in the intake passage is distributed to each cylinder of the engine body 1 via the branch section 3, so that the air-fuel mixture concentration among the cylinders becomes uniform, resulting in good combustibility. is obtained.

Further, by improving fuel atomization, it is possible to widen the lean limit of the air-fuel mixture concentration, reduce harmful exhaust components such as CO, HC, and NOx, and lead to improved fuel efficiency.

The air flow injected from the nozzle holes 19a and 20a becomes stronger in the operating region where the differential pressure upstream and downstream of the throttle valve 7 is large and the throttle valve opening is small, that is, in low-load operation or idling region, so that the above-mentioned mixing occurs. Uniform air concentration is extremely effective in these operating regions.

According to the experimental results, when the air nozzle has a pair of nozzle holes as in the present invention, in the fuel injection state shown in FIG. Therefore, it was confirmed that it is most effective to sandwich the particles near point A in the figure on the boundary where they are about to scatter.

In other words, the surface tension of the liquid film is high in the liquid film flow area, so it is difficult to atomize it even if air is blown there.On the other hand, the droplet formation area is radially diffused, so air is blown in a concentrated manner. However, since the surface tension is low and the degree of convergence is large near the boundary point, the effect of atomization by air blowing is most remarkable.

In addition, in this embodiment, the air injection from the nozzle is performed by the differential pressure between the upstream and downstream sides of the throttle valve I, so when the pressure difference is large during idle linking, the air injection amount is particularly large and effective, but the air injection amount is large and effective. In order to increase the amount of air ejected in a region, air may be supplied to the nozzle using an air pump or the like.

As explained above, the present invention provides a system in which the injected fuel flux is moved from both sides of the injected fuel flux toward the boundary point where the fuel flux is about to scatter as droplets from the liquid film flow in a direction parallel to the intake air flow. By creating colliding air currents,
Since the fuel is diffused radially in one plane and its atomization is significantly promoted, the mixing property with the intake air is improved, and the fuel distribution property of each cylinder and the uniformity of the mixture concentration are improved.

In addition, since the mixing property is improved, the dilution of the air-fuel mixture concentration can be further promoted, which is advantageous in terms of exhaust gas countermeasures and leads to improved fuel efficiency.

In particular, if a nozzle is installed to inject air through a bypass intake passage that bypasses the throttle valve, it is possible to improve atomization by utilizing a large differential pressure even during idling when the intake air flow rate is small. Therefore, the effect is remarkable.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a conventional single point injection type fuel supply device, Fig. 2 is a cross-sectional view showing an embodiment in which the present invention is applied to the same type of fuel supply device, and Fig. 3 is a cross-sectional view showing a conventional single point injection type fuel supply device. In the diagrams showing the fuel injection state, A is a view seen from the direction of flow of intake air, B is a view seen from the same direction as FIG. 2, and FIG. 4 is a view showing an example of the arrangement of air nozzles. 6... riser stove part, 7... throttle valve, 8...
Intake passage, 9...fuel injection valve, 10...bypass intake passage, 19a, 20a...nozzle hole.

Claims (2)

[Scope of utility model registration request] (1) A button is pressed on the fuel supply system of an internal combustion engine in which a fuel injection valve is placed in the intake passage downstream of the throttle valve and upstream of the riser part, and droplets are removed from the liquid film flow of the fuel flux injected from the fuel injection valve. Near the boundary point where the fuel is about to scatter, the pair of O injection holes are parallel to the flow direction of the intake air, are located in a plane that includes the central axis of fuel injection, and are opposed to each other with the central axis of fuel injection at almost right angles. 1. A fuel supply device for a multi-cylinder internal combustion engine, characterized in that air nozzles are arranged to blow air so as to collide with each other. (2) Fuel supply for a multi-cylinder internal combustion engine according to claim 1, wherein the air nozzle is provided at the outlet end of a bypass intake passage that bypasses a throttle valve and communicates intake passages upstream and downstream thereof. Device.