Arrangements for electronically determining and adjusting the ignition time of an internal combustion engine

Abstract

The signals of one or more engine operating parameters, such as r.p.m. and throttle valve vacuum are altered by function generators to correspond to the desired relationship between ignition timing and the parameters that are taken into account. These altered signals are added together and conducted to a comparator that receives as a second input a time and r.p.m. dependent signal from a saw tooth generator, the output of the comparator being fed to the ignition device. .Iadd.

We claim: 
     
       1. An ignition arrangement for internal combustion engines, comprising in combination first means for generating a first variable electrical signal absolutely indicative of crankshaft position; second means for generating as a function of at least one engine operating variable a second variable electrical signal indicative of a crankshaft position at which an ignition spark is to be produced; comparator means for comparing said first and second signals and for generating an ignition signal when the crankshaft position indicated by said first signal corresponds to the crankshaft position indicated by said second signal; and igniting means for producing an ignition spark in response to generation of said ignition signal. 
     
     
       2. An arrangement as defined in claim 1, wherein said first means comprises means for generating a saw-tooth waveform each pulse of which is initiated at a fixed time relative to the combustion cycle and has a slope proportional to engine speed. 
     
     
       3. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as a function of a plurality of engine operating variables. 
     
     
       4. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as a function of engine speed. 
     
     
       5. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as a function of engine speed and accelerator position. 
     
     
       6. An arrangement as defined in claim 1, wherein said second means comprises a plurality of transducers for generating respective electrical monitoring signals indicative of said operating variables, and plurality of function generators each associated with one of said transducers for producing a respective output signal as a respective predetermined function of the respective monitoring signal, and adder means for generating said second signal as the sum of said output signals. 
     
     
       7. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as a function of engine speed and throttle-valve vacuum. 
     
     
       8. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as a function of temperature. 
     
     
       9. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as a function of engine speed and throttle-valve position. 
     
     
       10. An arrangement as defined in claim 1, and further including means for applying to said igniting means ignition signals at predetermined unvarying angular positions of the crankshaft when the engine speed falls below a predetermined value. 
     
     
       11. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as an adjustable function of at least one engine operating variable. 
     
     
       12. An arrangement as defined in claim 1, wherein said second means comprises means for generating said second signal as an adjustable function of a plurality of engine operating variables. 
     
     
       13. An ignition arrangement for internal combustion engines, comprising in combination first means for generating a first variable electrical signal indicative of crankshaft position independently of engine speed; second means for generating as a function of at least one engine operating variable a second variable electrical signal indicative of a crankshaft position at which an ignition spark is to be produced; comparator means for comparing said first and second signals and for generating an ignition signal when the crankshaft position indicated by said first signal corresponds to the crankshaft position indicated by said second signal; and igniting means for producing an ignition spark in response to generation of said ignition signal.