Precision distributorless ignition control system for internal combustion engines

• US 4,649,881 A
• Filed: 08/12/1985
• Issued: 03/17/1987
• Est. Priority Date: 08/17/1983
• Status: Expired due to Term

• Current Assignee: Electromotive Incorporated
• Original Assignee: Electromotive Incorporated
• Inventors: Long, Alexander
• Primary Examiner(s): Argenbright, Tony M.
• Application Number:
  US06/764,970
• Time in Patent Office: 582 Days
• Field of Search: 123/416, 123/417, 123/418, 123/606, 123/609, 123/611, 123/643
• US Class Current: 123/406.63
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02P 5/1502 using one central computing unit
• CPC Class Codes: F02P 7/035 without mechanical switching means
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An electronic ignition system is disclosed for controlling as a function of a selected engine parameter the ignition instants of an internal combustion engine having at least one cylinder, a piston, a spark plug for effecting combustion in the cylinder and a rotatable crankshaft coupled to the piston to be rotatably driven as combustions within said cylinder occur at said ignition instants. The crankshaft has a reference position defining a positional relationship of the crankshaft to the cylinder. The ignition system includes an optical encoder directly coupled to the crankshaft for generating ignition signals upon the termination of a variable crankshaft arc beginning at a point fixed with respect to the reference position. The length of the crankshaft arc is set as a function of one or more selected engine parameters.

Claims

1. An electronic ignition system for controlling as a function of a selected engine parameter the ignition instants of an internal combustion engine having at least one cylinder, a piston, and a rotatable crankshaft coupled to said piston to be rotatably driven as combustions within said cylinder occur at said ignition instants, said crankshaft having at least one first reference position defining a positional relationship of said crankshaft to said cylinder, said crankshaft having a second reference position disposed a fixed angular distance before said first reference position considering the rotational direction of said crankshaft, said ignition instant intended to occur upon the termination of a variable crankshaft arc beginning at said second reference position, the length of said crankshaft arc determined as a function of said selected engine parameter, said electronic ignition system comprising:

(a) a rotor coupled to rotate with said crankshaft and having at least one first reference indicium and a plurality of N second reference indicia thereon for each first reference indicium, said first reference indicium positionally related to said second reference position, said second reference indicia including at least one second reference indicium aligned with said first reference indicium, said second reference indicia being spaced from each other by substantially equal angles;

(b) first and second signal generating means disposed at a point fixed in relation to the rotation of said crankshaft for providing respectively a first train of signals and a second train of signals, each first signal occurring in time when said first reference indicium rotates past said fixed point, each second signal occurring in time when each of said second reference indicia rotates past said fixed point;

(c) arc termination means initiated in response to said first signal for measuring said variable crankshaft arc in response to said second train of signal to provide a first ignition signal when said measured crankshaft arc equals the variable crankshaft arc set as a function of said selected engine parameter;

(d) reference position identifying means initiated in response to said first signal for measuring said fixed angular distance in response to said second train of signals to provide a second ignition signal when said measured crankshaft arc equals said fixed angular distance;

(e) closed loop circuit means comprising comparison means coupled to receive said second train of signals for providing an error signal;

(f) oscillator means for providing a corrected, third train of signals of a frequency proportional to the magnitude of said error signal; and

(g) feedback means for coupling said third train of signals to said comparison means, whereby said comparison means provides said error signal as a function of the phase difference between said first and third trains of signals.

2. The electronic ignition system as claimed in claim 1, wherein there is further included control means responsive to said first and second ignition signals for controlling the ignition instant as the first to occur of said first and second ignition signals.

3. The electronic ignition system as claimed in claim 1, wherein said reference position identifying means comprises counter means set with a count corresponding to said fixed angular distance, and said counter means is responsive to said second train of signals for incrementing said set count.

4. The electronic ignition system as claimed in claim 1, wherein there is included logic means operative in a first state when said error signal is substantially zero to use said first ignition signal to effect the ignition instant, and operative in a second mode when said error signal is not zero for using said second ignition signal to control the ignition instant.

5. An electronic ingition system for controlling a dwell period of an internal combustion engine as a substantially constant period of time, said internal combustion engine having at least one cylinder, a piston disposed within said cylinder, an ignition coil, a spark plug coupled to said ignition coil, a voltage source adapted to be coupled to said ignition coil during said dwell period and to be disconnected therefrom for an antidwell period beginning at an ignition instant causing a high voltage to be applied to said spark plug and combustion within said cylinder, and a rotatable crankshaft coupled to said piston to be rotatably driven as combustions occur within said cylinder, said crankshaft having at least one reference position defining the positional relationship of said crankshaft to said cylinder, said crankshaft having a second reference position disposed a fixed angular distance before said first reference position considering the rotational direction of said crankshaft, said ignition instant intended to occur upon the termination of a variable crankshaft arc beginning at said second reference position, said crankshaft arc determined as a function of a selected engine parameter, said electronic ignition system comprising:

(a) a rotor coupled to rotate with said crankshaft and having at least one first reference indicium and a plurality of N second reference indicia thereon for each first reference indicium, said first reference indicium positionally related to said second reference position, said second reference indicia including at least one second reference indicium aligned with said first reference indicium, said second reference indicia being spaced from each other by substantially equal angles;

(b) first and second signal generating means disposed at a point fixed in relation to the rotation of said crankshaft for providing respectively a first train of signals and a second train of signals, each first signal occurring in time when said first reference indicium rotates past said fixed point, each second signal occurring in time when each of said second reference indicia rotates past said fixed point;

(c) arc termination means initiated in response to said first signal for measuring said variable crankshaft arc in response to said second train of signals to produce an ignition signal when said measured crankshaft arc equals the variable crankshaft arc set a function of said selected engine parameter;

(d) crankshaft speed determining means response to crankshaft speed for providing a manifestation indicative of crankshaft speed;

(e) dwell/antidwell determining means initiated in response to said ignition signal for setting the length of said antidwell period in response to said crankshaft speed manifestation and for initiating said dwell period upon the termination of said antidwell period and for terminating said dwell period upon the occurrence of said ignition signal, whereby said dwell period is a substantially constant period of time regardless of crankshaft speed;

(f) closed loop circuit means comprising comparison means coupled to receive said second train of signals for providing an error signal;

(g) oscillator means for providing a corrected, third train of signals of a frequency proportional to the magnitude of said error signal; and

(h) feedback means for coupling said third train of signals to said comparison means, whereby said comparison means provide said error signal as a function of the phase difference between said first and third trains of signals.

6. The electronic ignition system as claimed in claim 5, wherein there is further included reference position identifying means initiated in response to said first signal for measuring said fixed angular distance in response to said second train of signals to provide a second ignition signal when said measured crankshaft arc equals said fixed angular distance, and OR logic means coupled to receive said first mentioned and second ignition signals to effect ignition upon the first to occur of said first mentioned and second ignition signals.

7. The electronic ignition system as claimed in claim 5, wherein there is included reference position identifying means initiated in response to said first signal for measuring said fixed angular distance in response to said second train or signals to provide a second ignition signals when said measured crankshaft arc equals said fixed angular distance.

8. The electronic ignition system as claimed in claim 7, wherein there is included logic means operative in a first mode in response to said error signal being substantially zero for terminating said dwell period upon the occurrence of said first mentioned ignition signal and for initiating said dwell period upon the termination of said antidwell period, and in a second mode of operation in response to said error signal not being substantially zero for terminating said dwell period upon the occurrence of said second ignition signal and for initiating said dwell period upon the occurrence of said first signal.

9. An electronic ignition system for controlling as a function of at least first and second selected engine parameters the ignition instants of an internal combustion engine having at least one cylinder, a piston and a rotatable crankshaft coupled to said piston to be rotatably driven as combustions within said cylinder occur at said ignition instants, said crankshaft having at least one reference position defining a positional relationship of said crankshaft to said cylinder, said crankshaft having a second reference position disposed a fixed angular distance before said first reference position considering the rotational direction of said crankshaft, said ignition instants intended to occur upon the termination of a variable crankshaft arc beginning at said second reference position, the length of said crankshaft arc determined as a function of said first and second selected engine parameters, said electronic ignition system comprising:

(a) a rotor coupled to rotate with said crankshaft and having at least one first reference indicium and a plurality of N second reference indicia thereon for each first reference indicium, said first reference indicium positionally related to said second reference position, said second reference indicia including at least one second reference indicium aligned with said first reference indicium, said second reference indicium, said second reference indicia being spaced from each other by substantially equal angles;

(b) first and second signal generating means disposed at a point fixed in relation to the rotation of said crankshaft for providing respectively a first train of signals and a second train of signals, each first signal occurring in time when said first reference indicium rotates past said fixed point, each second signal occurring in time when each of said second reference indicia rotates past said fixed points;

(c) arc determining means initiated in response to said first signal for measuring said variable crankshaft arc in response to said second train of signals to provide an ignition signal when said measured crankshaft arc equals said crankshaft arc set as a function of said first and second selected engine parameters;

(d) first and second parameter sensing means for providing respectively first and second parameter signals indicative of the magnitude of said sensed first and second selected engine parameters, said first parameter sensing means being responsive to crankshaft rotation for providing said first parameter signal to be indicative of crankshaft speed, said second parameter sensing means responsive to manifold vacuum for providing said second parameter signal indicative of engine load;

(e) memory means for storing a plurality of values of the length of said variable crankshaft arc addressable as a function of said first and second selected engine parameters, said memory means comprising a plurality of first memory sections, each first memory section storing values of the length of said variable crankshaft arc empirically determined for a particular engine to achieve a maximum mean torque output from said internal combustion engine as a function of said first selected engine parameter, each first section of said memory means storing values of said variable crankshaft arc empirically determined for one value of said second selected engine parameter, and a second memory section storing values of the length of said variable crankshaft arc determined empirically to effect a given engine function and value of the length of said variable crankshaft arc for implementing engine idle control, said engine being set to idle at a predetermined crankshaft speed, said values of the length of said variable crankshaft arc increasing inversely proportional to crankshaft speeds less than said predetermined crankshaft speed;

(f) means responsive to said second parameter signal for addressing a corresponding section of said memory means, responsive to said first parameter signal for addressing a value of the length of said variable crankshaft arc stored within said addressed section and for loading said addressed value of the length of said crankshaft arc in said arc determining means, whereby said ignition signal occurs at a point in time as a function of said first and second selected engine parameters, said addressing means being responsive to values of said first parameter signal below a first predetermined level and said second parameter signal above a predetermined level for addressing said second memory section, said addressing means being responsive to values of said second parameter for addressing a value of said variable crankshaft arc as a function of crankshaft speed and for transferring said addressed value to said arc determining means.