Electronic ignition timing system for internal combustion engines

Claim 3

A system as defined in claim 1 wherein said first and second characteristics of said engine are crankshaft speed and manifold vacuum, respectively.

Claim 4

A system as defined in claim 1 wherein said function generating means includes a memory device programmed in accordance with the relationship of the timing of ignition pulses to said first and second characteristics of said engine.

Claim 5

A system as defined in claim 3 wherein said memory device is programmed in accordance with the slope and limit of a piece-wise linear approximation of the relationship of the timing of ignition pulses to said first and second characteristics of said enGine, and said function generating means includes memory sequencing means connected to said comparing means and to said memory device for causing said memory device to provide said third digital signals sequentially, said third digital signals being representative of the slopes and limits of sequential segments of the relationship of the timing of ignition pulses to said first and second characteristics of said engine.

Claim 6

A system as defined in claim 4 wherein said comparing means includes first counter means connected to said first and second signal generating means for successively receiving said first and second digital signals, second counter means connected to said memory device and to said memory sequencing means for receiving the portions of said third digital signals representative of the limits of said sequential segments and for providing sequencing signals to said memory sequencing means when said second counter means has counted through a number of states representative of the limits of said sequential segments, and third counter means connected to said memory device and to said first and second counter means for providing pulses to said first and second counter means at rates proportional to the slopes of said sequential segments, said first counter means providing output signals indicative of the results of the comparisons.

Claim 7

A system as defined in claim 5 wherein said accumulating means includes a counter for counting clock pulses in synchronism with third counting means.

Claim 8

A system as defined in claim 1 wherein said first signal generating means includes a transducer means for providing pulse signals representative of engine speed, and a signal generator connected to said transducer means for converting the signals therefrom to said first digital signals.

Claim 9

A system as defined in claim 7 wherein said transducer means provides pulse signals at predetermined intervals of crankshaft rotation of said engine, and said signal generator includes a first counter for counting clock pulses scaled by a predetermined factor between successive ones of the pulses from said transducer means for generating a number N and a second counter including a register connected to said first counter to which the number N is transferred, said second counter for counting clock pulses in groups of N clock pulses each and for providing output pulses after each group of N pulses has been counted whereby a predetermined number of output pulses of said second counter are provided equally spaced between successive ones of the pulses from said transducer means.

Claim 10

A system as defined in claim 7 wherein said pulse generating means is connected to said transducer means and to said signal generator for counting a number of pulses from said signal generator equal to one of said timing values after each pulse signal from said transducer means.

Claim 11

An electronic system for controlling exhaust emissions of an internal combustion engine by varying the timing of ignition pulses in response to the speed and vacuum of said engine comprising: first signal generating means for providing first digital signals representative of the speed of said engine; second signal generating means for providing second digital signals representative of the vacuum of said engine; function generating means for sequentially providing third digital signals representative of the slopes and limits of piece-wise linear segments of the relationship of the timing of ignition pulses to the speed and vacuum of said engine for controlling exhaust emissions of said engine; comparing means, including counter means, connected to said first and second signal generating means and to said function generating means for comparing said first and second digital signals to said third digital signals by counting in said counting means in response to said third digital signals; accumulating means connected to said comparing means for counting in synchronism with said counting means for accumulaTing timing values responsive to the results of comparisons between said first and second digital signals and said third digital signals; and pulse generating means connected to said accumulating means for generating ignition pulses at times responsive to said timing values.

Claim 12

An electronic system for controlling exhaust emissions of an internal combustion engine by varying the timing of ignition pulses in response to the speed and vacuum of said engine comprising: first signal generating means for providing first digital signals representative of the speed of said engine; second signal generating means for providing second digital signals representative of the vacuum of said engine; function generating means for sequentially providing third digital signals representative of the slopes and limits of piece-wise linear segments of the relationship of the timing of ignition pulses to the speed and vacuum of said engine for controlling exhaust emissions of said engine; comparing means, including counter means, connected to said first and second signal generating means and to said function generating means for comparing said first and second digital signals to said third digital signals by counting in said counting means in response to said third digital signals; accumulating means connected to said comparing means for counting in synchronism with said counting means for accumulaTing timing values responsive to the results of comparisons between said first and second digital signals and said third digital signals; and pulse generating means connected to said accumulating means for generating ignition pulses at times responsive to said timing values.

Claim 13

An electronic system as defined in claim 10 wherein said first signal generating means includes transducer means for providing pulses at predetermined intervals of crankshaft rotation of said engine, interpolator means connected thereto for providing a predetermined number of equally spaced pulses between successive ones of the pulses from said transducer means, and second counter means connected to said interpolator means for providing said first digital signals.

Claim 14

An electronic system as defined in claim 11 wherein said interpolator means includes a first counter for counting clock pulses scaled by said predetermined number between successive pulses from said transducer means, a register connected to said first counter for retaining digital signals provided by said first counter, and a second counter connected to said register for counting clock pulses in groups determined by the digital signals retained by said register and for providing an output signal after each of the groups of clock pulses counter thereby.

Claim 15

An electronic sysem as defined in claim 11 wherein said pulse generating means is connected to said transducer means and to said interpolator means for counting a number of pulses from said interpolator means equal to one of said timing values after each pulse from said transducer means.

Claim 16

An electronic system as defined in claim 10 wherein said counter means of said comparing means includes a first counter connected to said function generating means for providing output pulses corresponding to clock pulses scaled by portions of said third digital signals representative of said slopes of said segments, a second counter connected to said first counter and to said function generating means for counting output pulses from said first counter and for sequencing said function generating means when the numbers of output pulses from said first counter equal portions of said third digital signals representative of said limits of said segments to provide the next successive ones of said third digital signals, and a third counter connected to said first counter for determining when the numbers of pulses from said first counter equal said first and second digital signals.

Claim 17

An electronic system as defined in claim 14 wherein said function generating means includes a memory device for providing said third digital signals, and a memory sequencer connected to said memory device and to said second counter for sequencing said memory device in response to output pulses from said second counter.