Fuel injection quantity control system for starting a two-cycle

Details Fuel injection quantity control system for starting a two-cycle Fuel injection quantity control system for starting a two-cycle

1992-01-10

1993-08-10

Dolinar, Andrew M.

Internal-combustion engines

Charge forming device

Fuel injection system

F02D 4106

Patent

active

052339653

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a two-cycle engine, and particularly to a system of controlling a fuel injection quantity for starting.
2. Background Art
In two-cycle engines for motorcycles and snowmobiles employing a fuel supply system by means of a carburetor, an exhaust port is opened during scavenging air, therefore, some air-fuel mixture (new air) passes through a cylinder with combustion gas. Consequently, fuel consumption is increased. Accordingly, instead of such a conventional fuel supply system by means of carburetor, two-cycle engines for motorcycles and snowmobiles frequently employ a fuel supply system of electronically controlled fuel injection type using a fuel injection valve. (Refer to, for example, Japanese Unexamined Patent Publication No. 63-255543.) This sort of system provides the intake manifold of each cylinder with a fuel injection valve to simultaneously inject fuel to all cylinders.
The fuel injection quantity control for starting the two-cycle engine of electronically controlled fuel injection type is achieved as follows.
A slightly larger fuel injection quantity in starting a two-cycle engine than in normally driving the engine is set, thereby easily starting the engine.
When an ignition switch is turned to a start position for cranking the engine, a value expressed with the following equation is output. T.sub.ILNTWK a basic fuel injection quantity for starting the engine, K.sub.LN a rotational speed factor, and K.sub.LT a time factor.
The basic fuel injection quantity which differs depending on engine temperature is stored in advance in a memory. The rotational speed factor changes depending on cranking speed. The time factor changes depending on cranking time.
As shown in FIG. 9, the time factor K.sub.LT set depending on time is updated at a predetermined interval of time (for example, 65 ms) by subtracting a predetermined value .DELTA.K.sub.LT (1at first).
Namely, the time factor K.sub.LT is successively updated according to K.sub.LT =K.sub.LT -.DELTA.K.sub.LT and decreased according to elapsing time as shown in FIG. 10.
Such a two-cycle engine shows the following problem in case the engine was started and once driven to a complete combustion state, thereafter, due to a certain reason, the engine stalled and was then restarted.
Namely, the time factor K.sub.LT is newly set for every starting operation, thereby setting a large time factor in correcting a fuel injection quantity for restarting the engine. As a result, the actual fuel injection quantity exceeds the required fuel injection quantity of the engine, thereby setting an air-fuel ratio to be too dense and failing in restart (FIG. 11).
In view of the problem of the conventional system, an object of the present invention is to provide a fuel injection quantity control system for starting a two-cycle engine for easily restarting the engine by setting a time factor to be suitable for cranking time in such a way that the fuel injection quantity may not exceed the required fuel injection in restarting the engine, thereby improving the starting operation of the engine.


DISCLOSURE OF THE INVENTION

To achieve the object, as shown in FIG. 1, a fuel injection quantity control system for starting a two-cycle engine according to the present invention comprising: a fuel injection valve; a means for correcting a basic injection quantity for starting the engine stored in advance in a memory depending on the engine temperature depending on cranking speed; and a means for correcting said basic fuel injection quantity depending on cranking time; provides as the means for correcting said basic fuel injection quantity depending on cranking time: a time factor setting means for updating, at predetermined intervals; a time factor by subtracting a predetermined subtrahend from a last time factor; a first subtrahend setting means for setting a first subtrahend to be applied to the time factor at a first engine start; a start judging means for judging, when an engine start is detected, whether it is a secon

REFERENCES:
patent: 4432325 (1984-02-01), Auracher et al.
patent: 4735184 (1988-04-01), Kasanami et al.
patent: 4765300 (1988-08-01), Fujimura et al.
patent: 5074271 (1991-12-01), Suzuki et al.

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