Auxiliary circuit for electronic fuel control systems to facilitate cold starting

Claim 2

In combination with an energizable internal combustion engine fuel control system of the type having engine operating parameter sensors including triggering means responsive to engine crank angle operative to generate signals indicative of engine crank angle and engine temperature sensor means operative to generate a signal having a level which increases in response to decreases in sensed temperature, a computing means responsive to the engine sensors for controlling the actuation of injector valve means whereby the quantity of fuel delivered to the engine is controlled, the improvement comprising circuit means responsive to the engine temperature sensor operative to produce an output pulse having a duration directly related to the level of sensed signal whereby the injector valve means may be actuated by the pulse to provide a quantity of fuel in proportion to pulse duration for cold starting of the engine, and including means operative to limit pulse production to a predeterminable maximum number of pulses per fuel system energization and without regard to the triggering means signals.

Claim 3

The system as claimed in claim 1 wherein said circuit means comprise first and second circuit, said first circuit operative to inhibit operation of said second circuit for a predetermined period of time and said second circuit operative to produce an output pulse having a duration indicative of the cold starting fuel requirement.

Claim 4

The system as claimed in claim 2 wherein said first circuit is comprised of a monostable multivibrator having a fixed-time period of instability and said second circuit is a monostable multivibrator having a variable time period of instability.

Claim 5

The system as claimed in claim 1 wherein said circuit means comprise means for receiving a signal having a magnitude which is related to the difference between a selected temperature and the temperature of the engine and monostable multivibrator means responsive to said signal to produce an output pulse having a time duration proportional to the magnitude of said signal.

Claim 6

A fuel control system for engines having an energizable electrical system comprising: sensory means operative to sense operating parameters of the engine and to produce signals representative of sensed parameters, including means responsive to engine crank angle operativE to generate signals indicative thereof; at least one of said sensory means being engine temperature sensor means operative to produce a signal having a signal level indicative of engine temperature; computing circuit means energizable in relation to the energization of the engine electrical system responsive to said sensory means operative to generate an output signal indicative of an engine demand for fuel and adapted to control injector valve means to thereby control the delivery of fuel to the engine; and cold start circuit means responsive to said engine temperature sensor means signal when said signal level is indicative of a need for additional fuel operative to generate a pulse signal having a duration which varies in response to variations in the temperature signal level indicative of the cold-starting fuel requirement and adapted to actuate injector valve means and including means responsive to said computing means energization operative to limit maximum additional fuel delivery to a predeterminable amount for each computing means energization and without regard to the engine crank angle signal.

Claim 7

A fuel control system for engines having an energizable electrical system comprising: sensory means operative to sense operating parameters of the engine and to produce signals representative of sensed parameters, including means responsive to engine crank angle operativE to generate signals indicative thereof; at least one of said sensory means being engine temperature sensor means operative to produce a signal having a signal level indicative of engine temperature; computing circuit means energizable in relation to the energization of the engine electrical system responsive to said sensory means operative to generate an output signal indicative of an engine demand for fuel and adapted to control injector valve means to thereby control the delivery of fuel to the engine; and cold start circuit means responsive to said engine temperature sensor means signal when said signal level is indicative of a need for additional fuel operative to generate a pulse signal having a duration which varies in response to variations in the temperature signal level indicative of the cold-starting fuel requirement and adapted to actuate injector valve means and including means responsive to said computing means energization operative to limit maximum additional fuel delivery to a predeterminable amount for each computing means energization and without regard to the engine crank angle signal.

Claim 8

The system as claimed in claim 5 wherein the engine fuel system includes a fuel-pumping means and said second circuit means includes a first circuit for establishing a fixed time delay operative to permit pressurization of the fuel-pumping means.

Claim 9

The system as claimed in claim 6 wherein said second circuit means includes a second circuit energizable after the fixed time delay and operative to produce an output signal having a duration which is a function of temperature drop below a selected temperature and means for applying an energization signal to said separate injector valve in response to said output signal.

Claim 10

The system as claimed in claim 5 wherein said second circuit means comprises signal generator means responsive to the engine temperature sensor operative to produce an output signal having a duration which is a function of temperature drop below a selected value.

Claim 11

The system as claimed in claim 8 wherein said signal generator means comprise a monostable multivibrator energized by a voltage whose magnitude is inversely related to the temperature drop below the selected value.

Claim 12

The system as claimed in claim 1 wherein said predeterminable maximum number is one.

Claim 13

In an internal combustion engine electronic fuel control system of the type comprising injector valve means actuable to discharge fuel upon receipt of an activation signal, energizable computing means operative to generate activation signals having a duration corresponding to the engine demand for fuel and a frequency in excess of the frequency of energization of the computing means, sensory means operative to provide signals for the computing means indicative of the engine demand for fuel, including engine temperature sensor means responsive to engine temperature to produce a signal having a level which varies in response to variations in sensed engine temperature, and circuit means intercommunicating the injector valve means and computing means and the sensor means, the improvement comprising cold start circuit means responsive to said engine temperature sensor means operative to generate an output pulse having a duration directly related to the engine temperature sensor signal level, means for communicating said pulse to the injector valve means, and inhibiting means operative to limit said circuit means output pulse productions to a predetermined maximum number of pulses per energization of the computing means.

Claim 14

In an internal combustion engine electronic fuel control system of the type comprising injector valve means actuable to discharge fuel upon receipt of an activation signal, energizable computing means operative to generate activation signals having a duration corresponding to the engine demand for fuel and a frequency in excess of the frequency of energization of the computing means, sensory means operative to provide signals for the computing means indicative of the engine demand for fuel, including engine temperature sensor means responsive to engine temperature to produce a signal having a level which varies in response to variations in sensed engine temperature, and circuit means intercommunicating the injector valve means and computing means and the sensor means, the improvement comprising cold start circuit means responsive to said engine temperature sensor means operative to generate an output pulse having a duration directly related to the engine temperature sensor signal level, means for communicating said pulse to the injector valve means, and inhibiting means operative to limit said circuit means output pulse productions to a predetermined maximum number of pulses per energization of the computing means.

Claim 15

The system as claimed in claim 11 wherein said cold start circuit means comprise a first and second circuit, said first circuit operative to inhibit operation of said second circuit for a predetermined period of time and said second circuit operative to produce an output pulse having a duration indicative of the cold starting fuel requirement.

Claim 16

The system as claimed in claim 12 wherein said first circuit is comprised of a monostable multivibrAtor having a fixed-time period of instability and said second circuit is a monostable multivibrator having a variable time period of instability.

Claim 17

The system as claimed in claim 11 wherein said cold start circuit means comprise means for receiving a signal having a magnitude which is related to the difference between a selected temperature and the temperature of the engine and monostable multivibrator means responsive to said signal to produce an output pulse having a time duration proportional to the magnitude of said signal.