Spark plug gap resistance meter

Claim 1

An apparatus for providing an indication of the resistance across a spark plug gap comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including an impedance and a constant voltage source, the series circuit and the spark plug gap combining to supply an output voltage across the impedance having a magnitude inversely proportional to the resistance across the spark plug gap; a capacitor; means for coupling the output voltage across the capacitor through a oneway current passing means to charge the capacitor to a voltage substantially equal to the output voltage; amplifying means having a high input impedance terminal and an output terminal; circuit means for applying the voltage on the capacitor to the high input impedance terminal, the amplifying means being responsive to the magnitude of the voltage applied to the high input impedance terminal for generating at its output terminal a signal directly related to said magnitude; and indicator means coupled to the output terminal of the amplifying means and responsive to the signal generated thereat for indicating the resistance across the spark plug gap.

Claim 2

An apparatus for providing an indication of the resistance across a spark plug gap comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including an impedance and a constant voltage source, the series circuit and the spark plug gap combining to supply an output voltage across the impedance having a magnitude inversely proportional to the resistance across the spark plug gap; a capacitor; means for coupling the output voltage across the capacitor through a oneway current passing means to charge the capacitor to a voltage substantially equal to the output voltage; amplifying means having a high input impedance terminal and an output terminal; circuit means for applying the voltage on the capacitor to the high input impedance terminal, the amplifying means being responsive to the magnitude of the voltage applied to the high input impedance terminal for generating at its output terminal a signal directly related to said magnitude; and indicator means coupled to the output terminal of the amplifying means and responsive to the signal generated thereat for indicating the resistance across the spark plug gap.

Claim 3

An apparatus for providing an indication of the resistance across a spark plug gap positioned in a combustion chamber and having a series of ignition voltage pulses applied thereacross to effect ignition of combustible materials injected into the combustion chamber comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including a first one-way current passing means, an impedance and a constant voltage source, the first one-way current passing means being poled so as to be reverse biased by the ignition voltage pulses applied across the spark plug gap and the constant voltage source being poled so as to forward bias the first one-way current passing means when said means is not reversed biased by the ignition voltage pulses, the series circuit and the spark plug gap combining to generate an output voltage across the impedance when the first one-way current passing means is not reverse biased by an ignition voltage pulse, the output voltage having a magnitude inversely proportional to the resistance across the spark plug gap; a capacitor; means for coupling the output voltage across the capacitor through a second one-way current passing means to charge the capacitor to a voltage substantially equal to the output voltage; amplifying means having a high input impedance terminal and an output terminal; circuit means for applying the voltage on the capacitor to the high input impedance terminal, the amplifying means being responsive to the magnitude of the voltage applied to the high input impedance terminal for generating at its output terminal a signal directly related to said magnitude, and indicator means coupled to the output terminal of the amplifying means and responsive to the signal generated thereat for indicating the resistance across the spark plug gap.

Claim 4

An apparatus for providing an indication of the resistance across a spark plug gap positioned in a combustion chamber and having a series of ignition voltage pulses applied thereacross to effect ignition of combustible materials injected into the combustion chamber comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including a first one-way current passing means, an impedance and a constant voltage source, the first one-way current passing means being poled so as to be reverse biased by the ignition voltage pulses applied across the spark plug gap and the constant voltage source being poled so as to forward bias the first one-way current passing means when said means is not reversed biased by the ignition voltage pulses, the series circuit and the spark plug gap combining to generate an output voltage across the impedance when the first one-way current passing means is not reverse biased by an ignition voltage pulse, the output voltage having a magnitude inversely proportional to the resistance across the spark plug gap; a capacitor; means for coupling the output voltage across the capacitor through a second one-way current passing means to charge the capacitor to a voltage substantially equal to the output voltage; amplifying means having a high input impedance terminal and an output terminal; circuit means for applying the voltage on the capacitor to the high input impedance terminal, the amplifying means being responsive to the magnitude of the voltage applied to the high input impedance terminal for generating at its output terminal a signal directly related to said magnitude, and indicator means coupled to the output terminal of the amplifying means and responsive to the signal generated thereat for indicating the resistance across the spark plug gap.

Claim 5

An apparatus for providing an indication of the resistance across a spark plug gap positioned in a combustion chamber and having a series of ignition voltage pulses applied thereacross to effect ignition of combustible materials injected into the combustion chamber comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including a first one-way current passing means, an impedance and a constant voltage source, the first one-way current passing means being poled so as to be reverse biased by the ignition voltage pulses applied across the spark plug gap and the constant voltage sOurce being poled so as to forward bias the first one-way current passing means when said means is not reversed biased by the ignition voltage pulses, the series circuit and the spark plug gap combining to generate an output voltage across the impedance when the first one-way current passing means is not reverse biased by an ignition voltage pulse, the output voltage having a magnitude inversely proportional to the resistance across the spark plug gap; a capacitor; means for coupling the output voltage across the capacitor through a second one-way current passing means to charge the capacitor to a voltage substantially equal to the output voltage, amplifying means having a high input impedance terminal and an output terminal; circuit means for applying the voltage on the capacitor to the high input impedance terminal, the amplifying means being responsive to the magnitude of the voltage applied to the high input impedance terminal for generating at its output terminal a signal directly related to said magnitude; indicator means coupled to the output terminal of the amplifying means and responsive to the signal generated thereat for indicating the resistance across the spark plug gap; a high impedance element; selectively operable switch means having a first position for coupling the high impedance element across the capacitor and a second position for decoupling the high impedance element from across the capacitor, whereby the voltage on the capacitor tracks the output voltage coupled thereacross through the second one-way current passing means to cause the meter means to provide a continuous indication of the instantaneous value of the resistance across the spark plug gap when the selectively operable switch means is in the first position and the capacitor is charged to a voltage substantially equal to the maximum output voltage coupled thereacross through the second one-way current passing means to cause the meter means to provide an indication of the minimum resistance across the spark plug gap when the selectively operable switch means is in the second position.

Claim 6

An apparatus for providing an indication of the resistance across a spark plug gap positioned in a combustion chamber and having a series of ignition voltage pulses applied thereacross to effect ignition of combustible materials injected into the combustion chamber comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including a first one-way current passing means, an impedance and a constant voltage source, the first one-way current passing means being poled so as to be reverse biased by the ignition voltage pulses applied across the spark plug gap and the constant voltage sOurce being poled so as to forward bias the first one-way current passing means when said means is not reversed biased by the ignition voltage pulses, the series circuit and the spark plug gap combining to generate an output voltage across the impedance when the first one-way current passing means is not reverse biased by an ignition voltage pulse, the output voltage having a magnitude inversely proportional to the resistance across the spark plug gap; a capacitor; means for coupling the output voltage across the capacitor through a second one-way current passing means to charge the capacitor to a voltage substantially equal to the output voltage, amplifying means having a high input impedance terminal and an output terminal; circuit means for applying the voltage on the capacitor to the high input impedance terminal, the amplifying means being responsive to the magnitude of the voltage applied to the high input impedance terminal for generating at its output terminal a signal directly related to said magnitude; indicator means coupled to the output terminal of the amplifying means and responsive to the signal generated thereat for indicating the resistance across the spark plug gap; a high impedance element; selectively operable switch means having a first position for coupling the high impedance element across the capacitor and a second position for decoupling the high impedance element from across the capacitor, whereby the voltage on the capacitor tracks the output voltage coupled thereacross through the second one-way current passing means to cause the meter means to provide a continuous indication of the instantaneous value of the resistance across the spark plug gap when the selectively operable switch means is in the first position and the capacitor is charged to a voltage substantially equal to the maximum output voltage coupled thereacross through the second one-way current passing means to cause the meter means to provide an indication of the minimum resistance across the spark plug gap when the selectively operable switch means is in the second position.

Claim 7

An apparatus for providing an indication of the resistance across a spark plug gap positioned in a combustion chamber and having a series of ignition voltage pulses applied thereacross to effect ignition of combustible materials injected into the combustion chamber comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including a first one-way current passing means, an impedance and a constant voltage source, the first one-way current passing means being poled so as to be reverse biased by the ignition voltage pulses applied across the spark plug gap and the constant voltage source being poled so as to forward bias the first one-way current passing means when said means is not reverse biased by the ignition voltage pulses, the series circuit and the spark plug gap combining to generate an output voltage across the impedance and having a magnitude inversely proportional to the resistance across the spark plug gap in the absence of an ignition voltage pulse, the voltage across the impedance being zero when the first one-way current passing means is reverse biased by the ignition voltage pulses; one shot multivibrator means coupled to the spark plug gap and responsive to an ignition voltage pulse for clamping the voltage across the impedance of the series circuit at zero potential for a predetermined time period following the ignition of the combustible material in the combustion chamber to prevent an erroneously high output voltage from appearing across the impedance resulting from excessive currents through the spark plug gap caused by combustion conditions within the combustion chamber; a capacitor; means for coupling the output voltage across the capacitor through a second one-way current passing means to charge the capacitor to a voltage having a magnitude substantially equal to the magnitude of the output voltage; amplifying means having a high impedance input teRminal and an output terminal; circuit means for coupling the voltage on the capacitor to the high impedance input terminal, the amplifying means being responsive thereto for generating a signal at the output terminal having a magnitude related thereto; and meter means coupled to the output terminal and responsive to the signal generated thereat for indicating the resistance across the spark plug gap.

Claim 8

An apparatus for providing an indication of the resistance across a spark plug gap positioned in a combustion chamber and having a series of ignition voltage pulses applied thereacross to effect ignition of combustible materials injected into the combustion chamber comprising a series circuit coupled in shunt with the spark plug gap, the series circuit including a first one-way current passing means, an impedance and a constant voltage source, the first one-way current passing means being poled so as to be reverse biased by the ignition voltage pulses applied across the spark plug gap and the constant voltage source being poled so as to forward bias the first one-way current passing means when said means is not reverse biased by the ignition voltage pulses, the series circuit and the spark plug gap combining to generate an output voltage across the impedance and having a magnitude inversely proportional to the resistance across the spark plug gap in the absence of an ignition voltage pulse, the voltage across the impedance being zero when the first one-way current passing means is reverse biased by the ignition voltage pulses; one shot multivibrator means coupled to the spark plug gap and responsive to an ignition voltage pulse for clamping the voltage across the impedance of the series circuit at zero potential for a predetermined time period following the ignition of the combustible material in the combustion chamber to prevent an erroneously high output voltage from appearing across the impedance resulting from excessive currents through the spark plug gap caused by combustion conditions within the combustion chamber; a capacitor; means for coupling the output voltage across the capacitor through a second one-way current passing means to charge the capacitor to a voltage having a magnitude substantially equal to the magnitude of the output voltage; amplifying means having a high impedance input teRminal and an output terminal; circuit means for coupling the voltage on the capacitor to the high impedance input terminal, the amplifying means being responsive thereto for generating a signal at the output terminal having a magnitude related thereto; and meter means coupled to the output terminal and responsive to the signal generated thereat for indicating the resistance across the spark plug gap.