Fuel injection control system

Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters

Reexamination Certificate

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Details

C123S041310

Reexamination Certificate

active

06247441

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a fuel-injected engine for an outboard motor. More particularly, the present invention relates to an improved fuel injection control system for a direct injection internal combustion engine used in a marine environment.
2. Related Art
Two cycle engines are widely used, particularly in applications where high specific outputs and relatively uncomplicated, simple engine constructions are desirable. Thus, two cycle engine are frequently employed as the power plant in a marine outboard motor because of the small space available in the powerhead of such engines and the demand for relatively high performance.
However, because of environmental concerns, there is a desire to significantly improve the performance of two cycle engines particularly in the area of exhaust emission control. One particularly advantageous method for reducing unburned hydrocarbons in the exhaust emissions without sacrificing engine performance is using direct cylinder injection.
It should be noted that, particularly in two-stroke applications, it is desirable to open and close the fuel injectors as rapidly as possible. The rapid opening and closely results in longer available injecting time. To accomplish this rapid opening and closing, the fuel injectors are provided with springs of sufficient stiffness to rapidly close the fuel injector while not causing a rebound opening upon closing. Accordingly, the increased spring stiffness requires a larger current to be circulated through a solenoid which controls opening and closing of the fuel injector.
If the engine speed increases, the fuel injector must be increasingly actuated or if the load on the engine increases, the actuation duration must be increased respectively. Either scenario results in increased energy sent to the transistor that controls the solenoid. The transistor, therefore, is susceptible to rapid increases in temperature over time. Accordingly, high-speed, high-load applications of direct cylinder injected engines or indirectly injected engines featuring certain configurations of injectors are subject to possible heat damage of the transistors.
SUMMARY OF THE INVENTION
Accordingly, one aspect of the present invention involves decreasing the operating temperature of such injector drivers. Another aspect of the present invention involves decreasing the engine speed during high-load, high-speed operating conditions.
Accordingly, one aspect of the present invention involves an engine control method comprising determining when a fuel injector driver overheat condition is impending and then initiating at least one of the following responses: reducing the speed of the engine by altering a volume of fuel injected by a fuel injector; reducing the speed of the engine by altering a timing of an initiation of fuel injection by the fuel injector; reducing the speed of the engine by altering an ignition timing; or activating a cooling fan to increase a level of heat transfer from the fuel injector driver.
Another aspect of the present invention involves an outboard motor comprising a power head. An internal combustion engine is mounted within the power head. The internal combustion engine preferably has at least one fuel injector with a fuel injector driver actuating the fuel injector. A fuel injector driver box preferably contains the fuel injector driver and a sensor capable of monitoring the temperature of the fuel injector driver. A control device preferably communicates with the sensor whereby the control device can initiate an engine speed reduction technique when the fuel injector driver temperature exceeds a predetermined temperature.
Yet another aspect of the present invention involves an engine comprising a cylinder block with at least one cylinder defined within the cylinder block. Preferably, at least one piston is arranged for reciprocation within the cylinder and the piston is connected to an output shaft. A combustion chamber is preferably defined within the cylinder between a cylinder head assembly and an upper surface of the piston. An induction system desirably communicates with the combustion chamber and comprises a throttle valve and a fuel injector. The fuel injector preferably includes an injector driver. An engine speed sensor is positioned proximate the output shaft and is capable of reading an engine speed while a throttle position sensor is capable of determining a throttle position angle. A control unit is in communication with the engine speed sensor and the throttle position sensor, wherein the control unit can initiate an injector driver cooling operation when the engine speed sensor indicates an engine speed above a predetermined engine speed and the throttle position sensor indicates a throttle position angle larger than a predetermined angle.


REFERENCES:
patent: 5150685 (1992-09-01), Porter et al.
patent: 5404843 (1995-04-01), Kato
patent: 5715793 (1998-02-01), Motose
patent: 5755207 (1998-05-01), Kushibe

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