Start-assist circuit

Details Start-assist circuit Start-assist circuit

1999-09-03

2001-10-30

Kwon, John (Department: 3747)

Internal-combustion engines

Charge forming device

Fuel injection system

C123S179160

Reexamination Certificate

active

06308688

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to internal combustion engines having fuel injectors and more particularly to circuitry for increasing the fuel injection solenoid voltage above that of the battery voltage during the starting process of such an engine.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
It is well known that starting an internal combustion engine can sometimes be difficult for engines that have fuel injectors which often run at fuel injector solenoid activation voltages greater than 13 to 14 volts as is typically provided by the battery. Since the amount of fuel provided to the engine may be determined by the voltage applied to the fuel injector solenoids, a fuel injector which may be required to deliver fuel demands necessitating up to a 40-volt input will be limited to the amount of fuel provided by a 13-to-14-volt input during the starting process. When the engine is running, a demand for fuel in excess of that provided by a 13-to-14-volt is not a problem since the engine alternator may provide an output of greater than 40 volts. However, during the starting process, the alternator, of course, does not generate sufficient output and the only power source generally available is the battery, which normally will have an output of 13 to 14 volts with minimal load and significantly less under the cranking load experienced during the starting process.
Therefore, it would be extremely advantageous to have a power source available during the startup of a fuel injected internal combustion engine which could provide a voltage output to the fuel injectors significantly higher than the battery voltage so that an effective charge of fuel could be provided to the cylinders of the internal combustion engine during the starting process.
SUMMARY OF THE INVENTION
The present invention provides an “assist” circuit for increasing the fuel injector voltage during starting of an engine having fuel injectors. The start-assist circuit includes a switch for providing an engine start signal and a voltage boost circuit for receiving a battery DC input that may be insufficient to provide the necessary fuel infection voltage during the engine start process and provides an increased output voltage. A control unit is included in the boost circuit and is connected to the start switch so that the boost circuit provides the increased voltage only when the start signal is received.
Therefore, it is an object of the present invention to provide apparatus and methods to make available to the fuel injectors of an internal combustion engine a voltage greater than the battery voltage during the starting process.


REFERENCES:
patent: 4753207 (1988-06-01), Wright
patent: 4774624 (1988-09-01), Qualich
patent: 5150687 (1992-09-01), Paganon et al.
patent: 5975058 (1999-11-01), French et al.

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