Engine and engine spark timing control with knock limiting etc.

• US 4,002,155 A
• Filed: 01/12/1976
• Issued: 01/11/1977
• Est. Priority Date: 01/12/1976
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Harned, John L., Herrick, Donald F.
• Primary Examiner(s): Geoghegan, Edgar W.
• Application Number:
  US05/648,313
• Time in Patent Office: 365 Days
• Field of Search: 123/148 E, 123/117 R, 123/119 R, 123/146.5 A, 73/35, 73/116
• US Class Current: 123/406.39
• CPC Class Codes: F02P 5/152 dependent on pinking detecting or indicating knocks in internal-combustion engines G01L23/22
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In a spark ignition internal combustion engine, an accelerometer is mounted on an engine component, preferably the intake manifold, and senses vibration including individual ringing vibrations due to engine knock or detonation. A reference signal is derived from the accelerometer signal during the portion of the engine cycle prior to possible knock-induced vibrations, which signal indicates the background accelerations due to noise. The number of individual ringing vibrations exceeding the reference signal during a predetermined amount of engine crankshaft rotation is counted. When the number of such counts exceeds a predetermined number during the predetermined crankshaft rotation, engine spark timing is retarded. If the number of such counts is less than a predetermined number during the predetermined crankshaft rotation, engine spark is advanced.

Claims

1. In an apparatus to generate sparking voltages at the spark electrodes of the respective cylinders of a spark ignition internal combustion engine in automotive application, the improvement comprising:

first means responsive at least to engine crankshaft rotation and effective to generate programmed spark voltage pulses and apply the same to the engine cylinders in sequence for the successive firings of each engine cylinder;

an accelerometer responsive to the background engine vibrations due to engine operation and the individual ringing engine vibrations due to engine knock;

a sampler responsive to the magnitude of the accelerometer signal during successive sample periods terminating, respectively, before ringing vibrations due to engine knock commence and effective to generate an output signal varying generally with the average magnitude of said accelerometer signal without said ringing vibrations;

a comparator simultaneously responsive to the sampler output signal and to the magnitudes of the individual ringing vibrations in said accelerometer signal and effective to generate a pulse each time the latter exceeds the former;

second means effective to count the number of said pulses during a predetermined counting time, said second means being further effective to change a stored number count in one direction by a predetermined number when the number of said pulses during said predetermined counting time exceeds a first reference number and to change said stored number count in the opposite direction by a predetermined number when the number of said pulses during said predetermined counting time does not exceed a second predetermined reference number no greater than said first predetermined reference number;

and means responsive to said second means to retard the sparking events due to said first means by a predetermined amount for each count stored by said second means and in sense to delay the spark as the second means senses increased numbers of ringing vibrations;

whereby knock intensity in said engine is limited to a desired level.

2. In an apparatus to generate sparking voltages at the spark electrodes of the respective cylinders of a spark ignition internal combustion engine in automotive application, the improvement comprising:

first means responsive at least to engine crankshaft rotation and effective to generate programmed spark voltage pulses and apply the same to the engine cylinders in sequence for the successive firings of each engine cylinder;

an accelerometer responsive to the background engine vibrations due to engine operation and the individual ringing engine vibrations due to engine knock;

a sampler responsive to the magnitude of the accelerometer signal during successive sample periods terminating, respectively, before ringing vibrations due to engine knock commence, and effective to generate an output signal varying with the average magnitude of said accelerometer signal without said ringing vibrations;

second means effective to count the number of individual ringing vibrations in said accelerometer signal that exceed said output signal by a predetermined low reference value during a predetermined first counting period and to count the number of individual ringing vibrations in said accelerometer signal that exceed said output signal by a predetermined higher reference value during a second predetermined counting period shorter than said first predetermined counting period, said second means being further effective to increase a stored number count by a predetermined number when either (a) the number of such vibrations in the first counting period exceeds a first predetermined reference count number or (b) the number of such vibrations in any of said second counting periods within the time of said first counting period exceeds a second predetermined reference count number smaller than said first reference count number and to decrease said stored number count by a predetermined number when both (a) the number of such vibrations in the first counting period is less than a predetermined number no greater than said first predetermined reference count number and (b) the number of vibrations in each of said second counting periods within the time of said first counting period is less than a predetermined number no greater than said second predetermined reference count number;

and means responsive to said second means to retard the sparking events due to said first means by a predetermined amount for each count stored by said second means the amount of said retard increasing with increasing stored count;

whereby knock intensity in said engine is limited to a desired level.

3. In an apparatus to generate sparking voltages at the spark electrodes of the respective cylinders of a vehicle mounted spark ignition internal combustion engine in automotive application, the improvement comprising:

first means responsive at least to engine crankshaft rotation and effective to generate programmed spark voltage pulses and apply the same to the engine cylinders in sequence for the successive firings of each engine cylinder;

an accelerometer responsive to the background engine vibrations due to engine operation and the individual ringing engine vibrations due to engine knock;

sampling means responsive to the magnitude of the accelerometer signal during successive sample periods terminating, respectively, before ringing vibrations due to engine knock commence and effective to generate an output signal indicative of the average value of said accelerometer signal during said sample periods;

means for generating a threshold signal from said output signal, said means comprising an amplifier effective to amplify said output signal by a fixed amount and means to add thereto a fixed bias, said fixed amount and fixed bias being predetermined to cause said threshold signal to approximate, over varying vehicle operating conditions, a level of engine knock just below that audible to an occupant of the vehicle;

a comparator responsive to the threshold signal and the magnitudes of the individual ringing vibrations in said accelerometer signal and effective to generate a pulse each time the latter exceeds the former;

second means effective to count the number of said pulses during a predetermined counting time, said second means being further effective to increase a stored number count by a predetermined number when the number of said pulses during said predetermined counting time exceeds a reference number and to decrease said stored number count by a predetermined number when the number of said pulses during said predetermined counting time does not exceed said reference number;

third means to generate a spark-creating voltage and apply the same to the engine cylinders in sequence; and

means responsive to said second means to retard the firings due to said first means by a predetermined amount for each count stored by said second means, the amount of said retard increasing with increasing stored count;

whereby knock intensity in said engine is limited to said level just below that audible to an occupant of the vehicle.

4. In an apparatus to generate sparking voltages at the spark electrodes of the respective cylinders of a spark ignition internal combustion engine in automotive application, the improvement comprising:

an accelerometer responsive to background accelerations due to engine operation and to individual ringing vibrations produced by knocking combustion;

a sampler responsive to the signal of the accelerometer during the successive times immediately prior to the occurrence of ringing vibrations due to engine combustion events, if knocking combustion occurs;

a comparator responsive to the output of the sampler and the magnitudes of individual ringing vibrations effective to produce an output pulse for each ringing oscillation that exceeds a reference amount determined by the output of said sampler;

a first counter responsive to said pulses and effective to count the same during a predetermined counting period;

a second counter responsive to said first counter and effective to make an increased count whenever the first counter counts more than a predetermined number during said predetermined counting period and to make a decreased count whenever the first counter counts less than a predetermined number during said predetermined counting period;

means responsive to engine crankshaft rotation effective to generate a pulse for the sparking events of the respective cylinders and in predetermined timed relation to the respective piston positions, said timing being advanced from the times knock free combustion is certain to occur under all engine operation conditions;

a third counter effective in response to each last mentioned pulse to count in accordance with successive increments of crankshaft rotation up to a count determined by the count of said second counter; and

means to generate a spark-creating voltage when said second counter reaches said count and to apply the same to the engine cylinders in sequence;

whereby spark events occur in the respective engine cylinders at times producing an average number of said individual ringing vibrations exceeding said reference amount, which average number is less than substantially the number of said first count.

5. In an apparatus to generate sparking voltages at the spark electrodes of the respective cylinders of a spark ignition internal combustion engine in automotive application, the improvement comprising:

first means responsive to engine operating conditions including engine crankshaft rotation effective to generate a first digital number for the sparking event of each cylinder representing the timing of said sparking event in relation to a reference crankshaft position, said timing being advanced from the times knock-free combustion is certain to occur under all variations of said engine operating conditions;

an accelerometer responsive to background accelerations due to engine operation and to individual engine ringing vibrations produced by knocking combustion;

a sampler responsive to the accelerometer signal during regularly short sample period at a time in the combustion cycle immediately prior to knock-induced ringing vibrations;

second means effective to count the number of said vibrations during a predetermined counting time a predetermined amount in excess of a reference level determined from the sampler signal, said means including a further counter effective to generate a second digital number by successively increasing the count on said last counter by a predetermined number when the number of such vibrations during said counting time exceeds a predetermined count number and decreasing the count of said last counter by a predetermined number when the number of such vibrations during said counting time does not exceed said predetermined count number;

means to generate a spark-creating voltage and apply the same to the engine cylinders in sequene; and

means responsive to engine crankshaft rotation and said first and second digital numbers to combine said first and second digital numbers arithmetically and actuate said last means, with respect to said reference crankshaft rotation in the sense of increased delay with increased numbers of ringing vibrations counted by said second means, in accordance with the arithmetic combination of said first and second digital numbers;

whereby the engine operates at its most effective spark timing value as determined by said first means while being limited to the spark timing as limited by knocking effects as determined by said second means.

6. The method of operating a spark ignition internal combustion engine in automobile usage, said engine having a plurality of cylinders within each of which a piston reciprocates in accordance with crankshaft rotation and an intake manifold through which gas is admitted to the respective cylinders for combustion in power strokes at successive uniformly spaced crank angles, comprising the steps of:

sensing acceleration of the manifold with rapidity of response sufficient to sense individual ringing vibrations associated with knock;

generating in a knock-free period immediately following the successive spark events in the respective cylinders a reference signal determined by the average acceleration of the manifold due to vibrations during such period;

counting, in each period when knock vibrations occur, if there is knocking, the number of times the sensed acceleration due to such vibrations exceeds a value determined by the reference signal;

retarding the engine spark event to all cylinders in unison by a predetermined fixed amount of crankshaft rotation when such count exceeds a first predetermined number during a predetermined crankshaft rotation at least substantially equal to the rotation between successive power strokes of the engine and advancing the engine spark event to all cylinders in unison by a like amount when the count is less than a second predetermined number no greater than said first predetermined number during such crankshaft rotation.

7. The method of operating a spark ignition internal combustion engine in automobile usage, the engine having a plurality of pistons which normally execute power strokes at successive uniformly spaced crank angles, comprising the steps of:

generating a spark timing voltage from the crankshaft position at times advanced from the times spark events should normally occur;

generating a first digital number determined by engine operating conditions and indicative of the retard of said spark timing voltage in terms of crankshaft rotation required for predetermined engine operation irrespective of knocking or detonation;

sensing the presence or absence of individual knock-induced ringing vibrations exceeding a predetermined magnitude during the successive power strokes of the engine;

counting the number of such individual vibrations during a predetermined amount of crankshaft rotation at least substantially equal to the crankshaft rotation between successive power strokes;

generating a second digital number of increasing the count on a counter by a predetermined number when the number last counted is greater than a first predetermined value and decreasing the count on the counter by a predetermined number when the number last counted is greater than a second predetermined value no greater than said first predetermined value; and

generating spark voltages for the engine in accordance with said first spark timing voltage, but delayed by an increment of crankshaft rotation units equal the difference of said first and second counting numbers.

8. A spark timing system for an internal combustion engine having a crankshaft and a plurality of spark plugs to which ignition voltage pulses are successively applied as the crankshaft rotates, comprising in combination:

first means responsive to individual knock-induced ringing vibrations of the engine in excess of a predetermined threshold level so as to provide a digital pulse signal not timed in relation to crankshaft rotation;

a first counter effective to count the number of pulses in said signal occurring during successive predetermined first angles of crankshaft rotation;

a second counter effective to increase its count when the count of the first counter is greater than a first predetermined number during any of a second predetermined number of successive predetermined first angles of crankshaft rotation and effective to decrease its count when the count of the first counter is less than a third predetermined number at most equal to said first predetermined number during all of said second predetermined number of predetermined first angles of crankshaft rotation;

second means to generate a spark timing pulse for each spark ignition event, each said pulse having a predetermined timing determined by mechanism not directly responsive to engine knock; and

third means to generate an ignition pulse for each spark timing pulse and effective to retard each ignition pulse from each spark timing pulse by a second angle of crankshaft rotation proportional to the count of the second counter.

9. A spark timing system for an internal combustion engine having a crankshaft and a plurality of spark plugs to which ignition voltage pulses are successively applied as the crankshaft rotates, comprising in combination:

first means responsive to individual knock-induced ringing vibrations of the engine in excess of a predetermined threshold level so as to provide a digital pulse signal not timed in relation to crankshaft rotation;

a first counter effective to count the number of pulses in said signal occurring during a predetermined first angle of crankshaft rotation;

a second counter effective to decrease its count when the first count is less than a first predetermined number during said first angle of crankshaft rotation and to increase its count when the first count is greater than a second predetermined number at least equal to said first predetermined number during said first angle of crankshaft rotation;

second means to generate a spark timing pulse for each spark ignition event, each said spark timing pulse having a predetermined timing determined by mechanism not directly responsive to engine knock; and

third means to generate an ignition voltage pulse for each spark timing pulse and effective to retard each ignition pulse from each spark timing pulse by a second angle of crankshaft rotation proportional to the count of said second counter.

10. A spark timing system for a multi-cylinder internal combustion engine having a crankshaft and a plurality of spark plugs to which ignition voltage pulses are successively applied as the crankshaft rotates, the rotation between successive ignition voltage pulses defining predetermined first angles, the engine completing an operating cycle upon each successive firing of one of said spark plugs, said system comprising in combination:

first means responsive to individual knock-induced ringing vibrations of the engine in excess of a predetermined threshold level so as to provide a digital pulse signal not timed in relation to crankshaft rotation;

a first counter responsive to said pulse signal and crankshaft rotation and effective to count the pulses in said pulse signal during each said predetermined first angle;

a second counter effective at substantially the beginning of each operating cycle to increase its count when said first counter has had at least a first predetermined number at the conclusion of any of the predetermined first angles in the immediately previous operating cycle and to decrease its count when said first counter has had less than a second predetermined number at most equal to said first predetermined number at the conclusion of all of the predetermined first angles in the immediately previous operating cycle;

second means to generate a spark timing pulse for each spark ignition event, each said pulse having a predetermined timing determined by mechanism not directly responsive to engine knock; and

third means to generate an ignition voltage pulse for each spark timing pulse and effective to retard each ignition voltage pulse from each spark timing pulse by a second angle of crankshaft rotation proportional to the count of said second counter, whereby the amount of retard, if any, of the ignition voltage pulses from the spark timing pulses is controlled by the cylinder having the greatest number of knock-induced ringing vibrations.

11. A spark ignition internal combustion engine suitable for vehicle use comprising an intake manifold of the type exhibiting ringing vibrations in response to engine knock and background vibration not related to engine knock, a crankshaft, and a plurality of cylinders with spark plugs to which ignition voltage pulses are successively applied as the crankshaft rotates to initiate combustion events in the cylinders, and further comprising:

an accelerometer mounted on the intake manifold and responsive to individual knock-induced ringing vibrations and the background vibrations;

a comparator responsive to the accelerometer and having a predetermined threshold level determined by said background vibrations so as to provide an output digital pulse signal for each individual ringing vibration in excess of the predetermined level;

a first counter effective to count the number of pulses in said signal occurring during successive predetermined first angles of crankshaft rotation;

a second counter effective to increase its count when the count of the first counter exceeds a first predetermined number during any of a second predetermined number of one or more such successive predetermined first angles of crankshaft rotation and effective to decrease its count when the count of the first counter is less than a third predetermined number at most equal to said first predetermined number during all of said second predetermined number of successive predetermined first angles of crankshaft rotation;

first means effective to generate a basic spark timing pulse for each spark ignition event, each said pulse having a predetermined timing determined by mechanism not directly responsive to engine knock; and

second means effective to generate an ignition pulse for each spark timing pulse and further effective to retard each ignition pulse from each spark timing pulse by a second angle of crankshaft rotation proportional to the count of the second counter, whereby engine knock, as measured by numbers of knock-induced ringing vibrations of said intake manifold in predetermined reference angles of crankshaft rotation, is limited to a predetermined maximum acceptable level.