Cold start auxiliary circuit for electronic fuel control system

Claim 2

In combination with an internal combustion engine fuel control system of the type having energizable computing means, a means to generate a signal indicative of engine temperature and injector valve means, the improvement comprising energizable circuit means responsive to the signal indicative of engine temperature and to its own energization and having a control electrode, operative to generate an output signal having a characteristic indicative of the engine cold starting fuel requirement, injector valve means responsive to said signal operative to deliver a quantity of fuel for cold starting of the engine in relation to the magnitude of the output signal variable characteristic and feedback-locking means coupled to said control electrode response to said output signal operative to bias said control electrode to prevent further actuation until said circuit has been deenergized for a predeterminable period of time.

Claim 3

The system as claimed in claim 1 wherein said locking means comprise means for applying a high-voltage potential to a portion of said circuit to render said portion of said circuit insensitive to false triggering.

Claim 4

The system as claimed in claim 2 wherein said circuit means includes an emitter coupled pair of transistors and said portion of said circuit comprises the base of one of said emitter coupled pair of transistors.

Claim 5

A fuel control system for engines having energizing means comprising in combination: sensory means operative to sense at least one operating parameter of the engine, including engine temperature sensor means operative to generate a signal having a level which varies in relation to sensed engine temperature; first energizable circuit means responsive to said sensory means operative to generate an output signal, said signal being comprised of a plurality of pulses having a duration indicative of the engine fuel requirement; injection valve means; at least a portion of said injection valve means adapted to receive said output signal and to be periodically intermittently energized in response thereto whereby fuel delivery to the engine may be controlled; and second energizable circuit means including means responsive to the engine temperature signal and means responsive to second circuit energization to generate a signal having a characteristic which varies with elapsed time from the moment of energization by the energizing means to receive and compare said temperature signal and said elapsed time signal and bistable switching means operative to be in one stable state when the temperature signal exceeds the elapsed time signal and to be in the other stable state when the elapsed time signal exceeds the temperature signal; said second circuit means further including latching means interconnecting said switching means and said comparison means operative to apply a bias signal to override said elapsed time signal whenever said switching means are in a selected one of their stable states whereby false triggering is prevented.

Claim 6

A fuel control system for engines having energizing means comprising in combination: sensory means operative to sense at least one operating parameter of the engine, including engine temperature sensor means operative to generate a signal having a level which varies in relation to sensed engine temperature; first energizable circuit means responsive to said sensory means operative to generate an output signal, said signal being comprised of a plurality of pulses having a duration indicative of the engine fuel requirement; injection valve means; at least a portion of said injection valve means adapted to receive said output signal and to be periodically intermittently energized in response thereto whereby fuel delivery to the engine may be controlled; and second energizable circuit means including means responsive to the engine temperature signal and means responsive to second circuit energization to generate a signal having a characteristic which varies with elapsed time from the moment of energization by the energizing means to receive and compare said temperature signal and said elapsed time signal and bistable switching means operative to be in one stable state when the temperature signal exceeds the elapsed time signal and to be in the other stable state when the elapsed time signal exceeds the temperature signal; said second circuit means further including latching means interconnecting said switching means and said comparison means operative to apply a bias signal to override said elapsed time signal whenever said switching means are in a selected one of their stable states whereby false triggering is prevented.

Claim 7

A fuel system as claimed in claim 4 wherein said second circuit comprises: means for receiving a variable signal indicative of engine temperature; means for receiving a time-varying signal; means for comparing said signals; said switching means responsive to said comparing means operative to produce an injector valve means control signal while said engine temperature signal exceeds said time-varying signal; and said disabling means are responsive to the termination of said control signal and are operative to apply a blocking signal to said comparing means.

Claim 8

The system as claimed in claim 5 wherein said switching means comprise a plurality of solid state switches having an ''''on'''' state and an ''''off'''' state and said disabling means are responsive to the change of state of one of said plurality of switches.

Claim 9

The system as claimed in claim 6 wherein said disabling means comprise: means for receiving a high voltage input signal; and means for communicating said signal to said comparing means.

Claim 10

The system as claimed in claim 5 wherein said comparing means comprise a pair of electronic devices and said time-varying signal and said high-voltage signal are applied to a control electrode of said pair of electronic devices.

Claim 11

The system as claimed in claim 8 wherein said time-varying signal is generated by the time required for the voltage across a capacitor to rise to a selected value whereby said capacitor accumulates electrical energy, said accumulated electrical energy operative to prevent switching of said switching means until said first and second circuit means have been deenergized for a predetermined period of time.

Claim 12

The system as claimed in claim 4 wherein said elapsed time signal-generating means comprise capacitive means chargeable in response to energization of said second circuit means and said comparison means comprise an emitter coupled pair of transistors having a pair of control electrodes arranged to receive on one control electrode the elapsed time signal and on the other control electrode the engine temperature signal.

Claim 13

The system as claimed in claim 10 wherein said switching means comprise electronic switches operative to change state when the state of conduction of the transistors in said emitter coupled pair reverses.

Claim 14

The system as claimed in claim 11 wherein said latching means interconnect said switching means with the elapsed time signal-receiving control electrode.