JPS633425Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a fuel injection device for an engine.

Conventionally, as shown in FIG. 1a, a multi-cylinder engine 1
, a so-called multi-point fuel injection device has been put into practical use, which injects and supplies fuel from each fuel injection valve 4, . . . , 4 provided in each intake passage 3, . However, in this type of fuel injection device, the fuel injection valve 4,
. . , 4 are required in the number corresponding to each intake passage 3, . Therefore, in order to improve this drawback, as shown in FIG. 1b, a fuel injection device (for example, Japanese Utility Model Application No. 55-20604 For example, two fuel injection valves 4,..., 4 are provided, and each intake passage 3,...,
A so-called single-point fuel injection device has been proposed that distributes and supplies an air-fuel mixture to three fuel injection systems.

Note that 5 in FIGS. 1a and 1b is a throttle valve.

The fuel injection valve of the latter device is installed upstream of the throttle valve in order to improve fuel atomization and distribution, and in order to ensure the amount of fuel injected at high engine output and improve tracking performance. The two fuel injection valves are configured to inject fuel alternately at equal intervals.

However, in this type of fuel injection device, when the opening degree of the throttle valve is small, such as when idling, the injected fuel flows along the top surface of the throttle valve and is sucked into the engine. If the arrangement direction of the fuel injection valves is not taken into account, even though fuel is injected at equal intervals from each fuel injection valve, there will be a difference in the distance that the fuel flows over the top surface of the throttle valve, which will cause the engine This increases fluctuations in the air-fuel ratio of the air-fuel mixture taken into the engine, which adversely affects the distribution of the air-fuel mixture to each cylinder, resulting in problems such as deterioration of engine performance and an increase in harmful substances in the exhaust gas. On the other hand, if the opening of the throttle valve is large, for example when it is fully open, there is no problem because the fuel injected from the fuel injection valve at even intervals hardly collides with the throttle valve and is drawn into the engine at even intervals. .

This idea was made in view of the above-mentioned conventional problems, and by arranging a plurality of fuel injection valves in the axial direction of the throttle valve, fluctuations in the air-fuel ratio at low throttle valve openings are reduced. This improves engine performance and exhaust gas at low speeds and low rotations.

Hereinafter, embodiments of this invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 2 and 3, the main intake passage 2
Two fuel injection valves 6 and 7 are arranged upstream of the throttle valve 5 in the direction of the axis 5a of the throttle valve 5 toward the throttle valve 5, and more preferably, the arrangement direction of the fuel injection valves 6 and 7 is arranged in the direction of the throttle valve 5. 5
offset with respect to the axis 5a.

Reference numeral 8 denotes a Karman vortex type intake air amount detection device that outputs a signal with a frequency proportional to the intake air amount, and 9 divides the signal from the detection device 8 at an appropriate frequency division ratio to generate the frequency-divided signal. each fuel injector 6,
This is a control circuit that alternately outputs a driving signal to 7 as a drive signal.

If the fuel injection device is configured as described above, even when the opening degree of the throttle valve 5 is small, the distance that the fuel injected from the fuel injection valves 6 and 7 follows the upper surface of the throttle valve 5 is equal, so that the fuel is injected. The air is drawn into the engine at approximately the same intervals as the air-fuel ratio, thereby making it possible to reduce fluctuations in the air-fuel ratio. Furthermore, in the above embodiment, since the fuel injection valves 6 and 7 are offset with respect to the axis 5a of the throttle valve 5, when the opening degree of the throttle valve 5 increases rapidly, such as during acceleration, the injected fuel is throttled. There is an advantage that the fuel is immediately sucked into the engine without colliding with the valve 5, and thus the fuel followability during acceleration can be improved.

In this invention, it is not necessary to use the Karman vortex type as the intake air amount detection device as in the above embodiment, and the intake air amount may be detected by another method.

Further, the number of fuel injection valves does not need to be two, and may be more than two.

As is clear from the above explanation, this invention aims to align the arrangement direction of the plurality of fuel injection valves located upstream of the throttle valve with the axial direction of the throttle valve, so that the injected fuel can be directed to the upper surface of the throttle valve. By making the distances along the throttle valves equal to each other, it is possible to reduce fluctuations in the air-fuel ratio when the throttle valve bottom opens, thereby improving engine performance and exhaust gas conditions.

[Brief explanation of the drawing]

1A and 1B are schematic diagrams of a conventional fuel injection device, FIG. 2 is a cross-sectional view of a fuel injection device according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view taken from FIG. 2. 1... Engine, 2... Main intake passage, 5... Throttle valve, 5a... Shaft, 6, 7... Fuel injection valve.

Claims (1)

[Scope of utility model registration request] In a fuel injection device for an engine, a plurality of fuel injection valves are provided in an intake passage upstream of a throttle valve, and fuel is alternately injected and supplied by the plurality of fuel injection valves at least when the throttle valve is at a bottom opening position, A fuel injection device for an engine, characterized in that the plurality of fuel injection valves are arranged in the axial direction of the throttle valve so that the distance that the injected fuel travels along the upper surface of the throttle valve is equal.