Abstract: A low pressure throttle body injection apparatus for a spark ignition internal combustion engine includes an injector mechanism mounted above a throttle body having at least one throttle bore with a throttle controlling flow therethrough. A valve controlled fuel injector is supported in a socket in the injector mechanism with its spray tip end positioned to inject fuel toward the throttle bore wall upstream of the throttle. An annular fuel well is defined by an internal socket wall and the exterior of the fuel injector, that is in communication with the valve end interior of the fuel injector via injector side ports. The injector mechanism defines a fuel inlet passage, including a fuel reservoir, opening into the fuel well and connectable to a source of low pressure fuel and a fuel return passage opening from the fuel well and connectable to the engine fuel supply tank. A pressure regulator connected in the fuel return passage is used to regulate the pressure of fuel in the fuel well.

Abstract: In a fuel injected vehicle engine having pulse generating apparatus for controlling the activation of a fuel injector for the duration of fuel injection pulses according to the fuel requirements of the engine, apparatus responsive to the normal duration of the pulses is effective, when the normal pulses are shorter than a predetermined minimum desired pulse duration, to increase simultaneously both the intervals between the pulses and the durations of the pulses by a common factor N from the normal interval and durations, to increase fuel flow accuracy at low fuel supply rates.

Abstract: In a pulse width modulated, fuel injected internal combustion engine having at least one injector characterized by transient fuel flow associated with injector opening and closing which tends to decrease the accuracy of the amount of injected fuel for short pulse durations, apparatus and method are provided for increasing the accuracy of injected fuel amount at low engine fuel requirements. When the normal determined pulse duration is less than a predetermined minimum pulse duration, the normal energization of the fuel injector is prevented and a number representing said determined pulse duration is summed in an accumulator. When the accumulator sum reaches the predetermined minimum pulse duration, the injector is energized for a duration at least equal to the predetermined minimum duration and the accumulator sum is reduced by a number corresponding to said duration.

Abstract: A fuel injection apparatus with wetting action for use on a spark ignition internal combustion engine has a fuel injector positioned coaxially above the upstream end of an associated upstanding cylindrical throttle bore in a throttle body so as to discharge liquid fuel in a pulsed spray pattern toward the bore wall above the circular disc type throttle valve pivotably supported in the throttle bore to control air flow therethrough. The spray pattern is such that at closed or nearly closed throttle liquid fuel droplets will travel to the bore wall and collect on the same so as to gravitate downward toward the small openings between opposite sides of the throttle and bore wall for pick up and vaporization by the then substantially sonic air flow through these openings and, under open throttle conditions, the fuel droplets are dispersed in the airstream flowing through the throttle bore before any substantial quantity can reach the bore wall.

Abstract: A memory type fuel control system and method of operating a motor vehicle internal combustion engine having a three-way catalytic converter. A fuel flow control system provides a fuel supply rate near the air/fuel ratio at which the catalytic converter has maximum three-way conversion efficiency. The fuel supply rate so determined is trimmed by a trim factor recalled from memory, the authority of this trim factor being sufficient to compensate for engine and controller variations with time, manufacturing tolerances, etc. In the preferred form, the trim factor is stored in memory at an address determined by the same engine operating conditions that control the fuel supply. The engine exhaust gas oxidizing/reducing conditions are sensed by exhaust gas sensors.

Abstract: A digital closed loop fuel control system for an internal combustion engine having a zirconia sensor which provides a signal changing abruptly between first and second values as the air/fuel ratio varies through a stoichiometric ratio. The output of the zirconia sensor is sampled at constant frequency sampling intervals and an up/down counter is set in one of its counting modes as a function of whether the air/fuel ratio is less than or greater than the stoichiometric ratio. During each sampling interval, a first number of clock pulses from a clock pulse generator are coupled to the up/down counter when the air/fuel ratio is greater than a stoichiometric ratio and a second number of the clock pulses are coupled to the up/down counter when the air/fuel ratio is less than the stoichiometric ratio.

Abstract: A combustible gas sensor for use in a closed loop fuel control system for a combustion engine comprises a pair of sensor conduits within the main exhaust conduit of the engine, with exhaust gas drawn through one of the sensor conduits and a mixture of exhaust gas and air drawn through the other by engine induction vacuum at controlled rates. A catalyst coated capillary tube within each secondary conduit has air drawn through it at a constant rate. On account of the catalytically induced combustion on its outer surface, the capillary tube exposed to the air-exhaust mixture heats more than the other by an amount dependent upon the concentration of combustible gas in the exhaust. The capillary tubes are connected in series; and the pressure at the junction, when compared with a reference, is a function of the combustible gas concentration. The use of two capillary tubes in each conduit connected in a "bridge" configuration eliminates the need for a separately generated reference pressure.