Engine fuel injection control apparatus with simultaneous pulse width and frequency adjustment

Claim 2

In a fuel injected vehicle engine including means effective to generate fuel injection pulses at first predetermined times separated by first intervals, the pulses having first variable durations the magnitude of which are determined by control means in accordance with engine fuel flow requirements and said first intervals, the engine further including means responsive to said pulses to inject fuel into the engine for the duration of said pulses, the injecting means thereby providing fuel to the engine in accordance with the requirements thereof but with an accuracy tending to decrease with decreasing pulse duration, the improvement comprising: means responsive to the first time duration of each of said fuel injection pulses as determined by said control means and effective, when said first pulse time duration is shorter than a predetermined minimum desired pulse duration, to generate and apply to the injecting means alternate fuel injection pulses having second intervals therebetween and second durations both increased by a common factor N from the first intervals and first durations, respectively, whereby the accuracy of the fuel injecting means is increased at low fuel supply rates.

Claim 3

In a fuel injected vehicle engine including means to inject fuel into the engine for the duration of fuel injection pulses with an accuracy tending to decrease with decreasing duration of said fuel injection pulses, apparatus for generating said fuel injection pulses comprising, in combination: first means effective to generate first fuel injection timing pulses at predetermined times separated by first time intervals; second means for generating first clock pulses at a first rate faster than that of the first fuel injection timing pulses; third means responsive to one or more engine operating parameters to repetitively compute a required fuel flow rate and generate fuel pulse numbers representative thereof; fourth means effective to compare said fuel pulse numbers to a reference indicative of a minimum desired fuel injection pulse duration and generate a first output when the numbers are less than said reference and a second output when the numbers are greater than said reference; fifth means responsive to the first clock pulses to generate alternative clock pulses at a rate slower than the rate of said first clock pulses by a factor N; sixth means responsive to the first means to generate alternative fuel injection timing pulses separated by intervals which are a multiple N of the first intervals; seventh means effective to generate a fuel injection pulse beginning with each fuel injection timing pulse and having duration equal to a fuel pulse number of clock pulses; eighth means responsive to the comparator to provide the first clock pulses and first fuel injection timing pulses to the seventh means while the comparator is in its first state and to provide the alternative clock pulses and alternative fuel injection timing pulses to the seventh means when the comparator is in its second state, whereby the fuel injection means can provide fuel accurately even when the first fuel injection pulse duration would be less than the minimum desired pulse duration.

Claim 4

In a fuel injected vehicle engine including means to inject fuel into the engine for the duration of fuel injection pulses with an accuracy tending to decrease with decreasing duration of said fuel injection pulses, apparatus for generating said fuel injection pulses comprising, in combination: first means effective to generate first fuel injection timing pulses at predetermined times separated by first time intervals; second means for generating first clock pulses at a first rate faster than that of the first fuel injection timing pulses; third means responsive to one or more engine operating parameters to repetitively compute a required fuel flow rate and generate fuel pulse numbers representative thereof; fourth means effective to compare said fuel pulse numbers to a reference indicative of a minimum desired fuel injection pulse duration and generate a first output when the numbers are less than said reference and a second output when the numbers are greater than said reference; fifth means responsive to the first clock pulses to generate alternative clock pulses at a rate slower than the rate of said first clock pulses by a factor N; sixth means responsive to the first means to generate alternative fuel injection timing pulses separated by intervals which are a multiple N of the first intervals; seventh means effective to generate a fuel injection pulse beginning with each fuel injection timing pulse and having duration equal to a fuel pulse number of clock pulses; eighth means responsive to the comparator to provide the first clock pulses and first fuel injection timing pulses to the seventh means while the comparator is in its first state and to provide the alternative clock pulses and alternative fuel injection timing pulses to the seventh means when the comparator is in its second state, whereby the fuel injection means can provide fuel accurately even when the first fuel injection pulse duration would be less than the minimum desired pulse duration.