Abstract: Methods and systems for detecting and correcting improper operation of a compressor in a refrigeration system and/or an HVAC system include a component level detection and prevention and a system level detection and prevention. The system level detection and prevention can be a backup or a confirmation of the component level detection and prevention. The component level detection and prevention can detect and prevent improper compressor operation within a predetermined time so that the compressor's operation period in an improper direction can be minimized, thereby minimizing wear and damage to the compressor.

Abstract: Described is a connection plug for connecting an ignition coil to a spark plug, comprising an electric line that has a first end for contacting an ignition coil and a second end for contacting the spark plug, a protective hose that surrounds the electric line, a protective pipe that surrounds the protective hose, wherein the protective hose is retained in the protective pipe in a positive-locking manner. The protective pipe has latching recesses at its ignition coil end, into which latching projections of the protective hose engage.

Abstract: A power supply control part supplies offset voltages from power supplies to each of signal wires at start time and then, after a predetermined delay time period, supplies a reference voltage from a power supply. A series resistor circuit of resistor elements is provided in each signal wire and a resistor element is connected between a supply node of the offset voltage and an input terminal of the series resistor circuit. A resistor element is connected between the supply node of reference voltage and the output terminal of the series resistor circuit provided in the signal wire of a high-potential side. A comparison logic part detects a disconnection of the signal wire based on a voltage developed at the input terminal of itself during the delay time.

Abstract: A mobile terminal, and a device and method for charging the same are provided. A power input of a Voltage Bus (VBUS) of a Universal Serial Bus (USB) interface in the mobile terminal is connected to a switch capable of switching off and switching on the power input of the VBUS. During charging, the mobile terminal controls the switch to control an input current to generate a specific current waveform; and a charging device is internally provided with a circuit for detecting the specific current waveform. If the circuit detects the specific current waveform generated by the mobile terminal, an output voltage of the charging device is increased to charge the mobile terminal. The charging device increases the charging power of the USB interface.

Abstract: A vehicle includes an engine, a transmission with a shift valve, an alternator, an auxiliary battery, a voltage sensor operable to measure an auxiliary voltage, and an electronic transmission range selection (ETRS) system. The ETRS system includes a controller, and also an electronic range selector device that transmits an electronic range request signal to the controller to request the shift of the transmission to a requested operating range. The controller executes a method to predict a loss of auxiliary power aboard the vehicle, and to control an action of the vehicle in response to the predicted loss of auxiliary power. The electronic range request signal is received from the range selector device and auxiliary voltage. The controller calculates a slope of a decrease in the measured auxiliary voltage. A control action is executed with the alternator is in the charging state and the calculated slope exceeds a calibrated slope threshold.

Abstract: There is provided an internal combustion engine ignition device which comprises a switching element for causing or interrupting flow of a current through a primary coil of an ignition coil; a secondary current detection circuit connected to a secondary coil for detecting a secondary current flowing at the time of ignition; an ion current detection circuit for detecting an ion current generated after the ignition; and an energy consumption circuit which is activated based on an output signal from the secondary current detection circuit that is output when the secondary current exceeds a predetermined threshold value, to constitute a circuit for discharging energy stored in the ignition coil.

Abstract: A self power circuit for ion sense circuitry is provided. The self power circuit is configured to supply the voltages required to generate and measure an ion current flow in a combustion chamber of an engine. The power circuit stores power from the current flow in the ignition coil secondary circuit during at least a portion of a sparking period for use during the ion current measurement period between sparking events. Ion current generation voltage as well as positive and negative sensor circuit power supply voltages are generated in one embodiment.

Abstract: A self power circuit for ion sense circuitry is provided. The self power circuit is configured to supply the voltages required to generate and measure an ion current flow in a combustion chamber of an engine. The power circuit stores power from the current flow in the ignition coil secondary circuit during at least a portion of a sparking period for use during the ion current measurement period between sparking events. Ion current generation voltage as well as positive and negative sensor circuit power supply voltages are generated in one embodiment.

Abstract: A coil tester for testing the functionality of a vehicle ignition coil that has been removed from its vehicle includes a circuit that can be quickly and conveniently connected between the ignition coil and a battery so as to provide a current of sufficient voltage to the ignition coil. The coil tester also includes a momentary switch for preventing overheating of the ignition coil and a scale for indicating the strength of the coil.

Abstract: A method providing diagnostics of operation of an internal combustion engine ignition coil further including at least one electric cable connecting the ignition coil to at least one spark plug installed in a cylinder head of the engine. The method temporarily introduces a voltage-controlled switch into the ignition circuit, causing the coil to supply a diagnostics voltage higher than a threshold value needed for the spark plug to form a spark, so as to cause a spark to form between the central electrode of the spark plug and a conducting element of the switch, and checks that a spark actually is formed in response to the supply.

Abstract: A simple “go or no go” ignition coil tester identifies coils that have failed or that are about to fail by driving a coil with sufficient voltage and amperage to operate at its peak output. Coils that have failed or that are close to failure cannot operate at peak output and thus fail the test. A standard kilovolt tester is used to simulate a spark plug and an audio indication of sparking produced by the kilovolt tester is used to confirm operation or failure of the coil. The system dispenses with short circuit and closed circuit test apparatus as well as the structures and failings associated with visual spark indicators.

Abstract: A system for detecting spark in an igniter for a gas turbine engine. An igniter generates a plasma, or spark, somewhat similar to an automotive spark plug. In the invention, an inductive pick-up is positioned adjacent the igniter, to detect current pulses in the igniter, to thereby infer the presence of spark. A detection system detects the spark, and informs the pilot of the aircraft of the detected spark. Thus, if the pilot encounters a problem in starting the engine, the pilot can rapidly determine whether the igniter is involved in the problem.

Abstract: A simple “go or no go” ignition coil tester identifies coils that have failed or that are about to fail by driving a coil with sufficient voltage and amperage to operate at its peak output. Coils that have failed or that are close to failure cannot operate at peak output and thus fail the test. A standard kilovolt tester is used to simulate a spark plug and an audio indication of sparking produced by the kilovolt tester is used to confirm operation or failure of the coil. The system dispenses with short circuit and closed circuit test apparatus as well as the structures and failings associated with visual spark indicators.

Abstract: The present invention relates to an ignition coil tester having a control module and an output electronics for testing the functioning of rod-type ignition coils, which is connectible to a diagnostic tester, the rod-type ignition coil having a primary winding and a secondary winding for generating the ignition voltage as well as a field guide plate, a plug connector and a secondary output. To be able to perform a component test on a rod-type ignition coil uninstalled from an internal combustion engine, the present invention provides for the ignition coil tester to have a housing and a spark plug dome for receiving the rod-type ignition coil, the dimensions and shape of which essentially correspond to those of a spark plug dome in an internal combustion engine and/or are adjustable to the dimensions of the latter.

Abstract: This feature of the present invention comprises a method and apparatus that provides a regulated power supply for in-cylinder ionization detection by harvesting the excess ignition coil leakage and magnetizing energy immediately following the turn off of the ignition coil IGBT. It uses an additional energy storage capacitor which replaces a first capacitor as the primary energy storage device. Thus, this feature of the present invention uses a two step method for charging the ionization detection circuit, as opposed to just one stage. The second capacitor is charged first, typically up to 400 Volts DC, and is then used as a reservoir to charge the first capacitor.

Abstract: A system and method for diagnosing ignition system performance of an internal combustion engine. The method operates an engine control unit to produce a sequence of spark ignition current pulses through primary windings of a plurality of ignition coils. The current pulses produce voltage pulses across electrodes of the spark plugs. The voltage pulses produce flyback voltages across the primary windings. Output pulses are produced in response to the flyback voltages having time durations related to the time durations of the sparks produced by the spark plugs. Digital signal are produced in response to each one of the output pulses representative of the spark time duration of a corresponding one of the sparks. A comparison of the digital signals determines whether the spark time duration of one of the spark plugs is substantially different from the spark time durations of the other ones of the plurality of spark plugs.

Abstract: The present feature of the invention is generally directed to a subsystem of an ignition diagnostics and feedback control system using ionization current feedback. It utilizes the ionization signal from an ionization detection circuit to monitor ignition parameters, such as primary charge timing, primary charge duration, ignition/spark timing, and ignition/spark duration for future “smart” ignition system control. In addition, the ionization signal is also used to detect spark plug carbon fouling, as well as plug insulator overheating. These parameters can be monitored for every cylinder of the engine for each engine cycle.

Abstract: A testing apparatus for testing a waste-power ignition coil is provided and includes an igniter simulator having a first switching device electrically connected to an output of the primary side of a waste-power ignition coil under test and a triggering means for changing a state of the first switching device at a predetermined interval. A second switching device bears a first pair of contacts being electrically connected to one of a positive going and negative going output of a secondary winding of the waste-power ignition coil under test and a second pair of contacts being electrically connected to another of a positive going and negative going output of the secondary winding of the waste-power ignition coil under test. The second switching device acts substantially synchronously with the igniter simulator actuator to ground a respective one of the positive going and negative going output of the secondary winding of the waste-power ignition coil under test to simulate a waste-stroke phase.

Abstract: A circuit for measuring ionization current in a combustion chamber of an internal combustion engine including an ignition coil, having a primary winding and a secondary winding, and an ignition plug. The ignition plug ignites an air/fuel mixture in the combustion chamber and produces an ignition current in response to ignition voltage from the ignition coil. A capacitor, charged by the ignition coil, provides a bias voltage producing an ionization current after ignition of the air/fuel mixture in the combustion chamber. A current mirror circuit produces an isolated current signal proportional to the ionization current. In the present invention, the ignition current and the ionization current flow in the same direction through the secondary winding of the ignition coil. The charged capacitor operates as a power source and, thus, the ignition current flows from the charged capacitor through the current mirror circuit and the ignition coil to the ignition plug.

Abstract: A coil-on plug testing apparatus generates an output signal representing an ignition signal. The testing apparatus includes an inductive sensor for detecting an electromagnetic flux generated by a coil-on plug device during a firing event and generating and outputting a voltage in response thereto, and a signal processing circuit electrically connected to the inductive sensor for generating an output signal in response to variations in the voltage output by the inductive sensor. A method for determining burn time for a coil-on plug ignition includes disposing an inductive sensor adjacent to a coil-on plug ignition housing, using the inductive sensor to detect an electromagnetic flux output by the coil-on plug ignition during a period encompassing at least one firing section, and determining a burn time by identifying a firing line, identifying an endpoint of a spark line and determining a time period therebetween.

Abstract: An apparatus for testing the actual functioning of an automotive coil includes a housing with a switch and a capacitor across the switch. Connections to ground and to a coil that is placed in series with the apparatus are provided. An opposite side of the coil either is or remains connected to a positive source of voltage, such as a battery in the automobile. The positive source of voltage is also connected to a visible spark tester. Cycling of the switch activates the coil and produces an arc that is visible in the spark tester. An additional circuit is provided in the housing that verifies the presence of a minimum required voltage.

Abstract: In an ignition coil assembly of an ion sensing ignition system having an ignition coil output, a buffered ion-sense current source circuit is provided and includes a current sensing circuit, the current sensing circuit being disposed so as to be communicated with the ignition coil output and an active current source circuit, the active current source circuit being disposed so as to be communicated with the current sensing circuit and a current measuring device.

Abstract: A circuit for measuring ionization current in a combustion chamber of an internal combustion engine including an ignition coil, having a primary winding and a secondary winding, and an ignition plug. The ignition plug ignites an air/fuel mixture in the combustion chamber and produces an ignition current in response to ignition voltage from the ignition coil. A capacitor, charged by the ignition coil, provides a bias voltage producing an ionization current after ignition of the air/fuel mixture in the combustion chamber. A current mirror circuit produces an isolated current signal proportional to the ionization current. In the present invention, the ignition current and the ionization current flow in the same direction through the secondary winding of the ignition coil. The charged capacitor operates as a power source and, thus, the ignition current flows from the charged capacitor through the current mirror circuit and the ignition coil to the ignition plug.

Abstract: A method includes diagnosing a solenoid circuit to determine if the circuit has begun to degrade. By measuring characteristics associated with the electrical waveform, it is determined if the characteristics of a solenoid circuit are different from the previously measured characteristics of the circuit, or of a known functioning circuit.

Abstract: Methods, apparatus, and systems for distinguishing between compression and exhaust strokes of a four-cycle engine is provided. A first ionization time of a spark plug for a known cylinder is measured on a first engine stoke. A second ionization time of the spark plug is measured on a second engine stroke. The second ionization time is compared to the first ionization time. It is determined that the engine stroke with the greater ionization time is a compression stroke.

Abstract: A coil-on plug testing apparatus generates an output signal representing an ignition signal. The testing apparatus includes an inductive sensor for detecting an electromagnetic flux generated by a coil-on plug device during a firing event and generating and outputting a voltage in response thereto, and a signal processing circuit electrically connected to the inductive sensor for generating an output signal in response to variations in the voltage output by the inductive sensor. A method for determining burn time for a coil-on plug ignition includes disposing an inductive sensor adjacent to a coil-on plug ignition housing, using the inductive sensor to detect an electromagnetic flux output by the coil-on plug ignition during a period encompassing at least one firing section, and determining a burn time by identifying a firing line, identifying an endpoint of a spark line and determining a time period therebetween.

Abstract: A method of detecting spark plug fouling in an internal combustion engine is provided. The method comprises calculating an integration value of discharge current flowing between electrodes of a spark plug during a period of a spark discharge and judging if the calculated discharge current integration value is smaller than an integration value criterion. The integration value criterion is set at such a value that can discriminate between normal discharge and interior jumping (i.e., jumping due to short circuit caused by fouling). When the calculated discharge current integration value is smaller than the integration value criterion, it is judged that the spark plug has been fouled. By this, it becomes possible to detect a spark plug fouling before the electrodes of the spark plug are short-circuited and disabled to generate spark discharge, i.e., before the spark plug is fouled to such an extent as to cause a misfire. An ignition system for detecting spark plug fouling is also provided.

Abstract: An improved system and method for adjusting an air gap in a core portion of an ignition coil includes a low-cost circuit for providing real-time determination of an inductance of one of the windings of the ignition coil being assembled. The circuit includes an AC power source in series relationship with a resistive element and the ignition coil. The circuit further includes a controller, such as a programmable logic controller (PLC) to read voltages across the resistor and ignition coil and calculate an inductance, using data determined in a calibration step. A machine is controlled to adjust the air gap until the calculated inductance equals a desired inductance. Reduced cost, and improved immunity to TIG welder noise is provided.

Abstract: An apparatus for determining component fault conditions associated with a capacitive discharge ignition system for an internal combustion engine includes a number of AC coupling circuits connected to a spark detection circuit, wherein the combination is responsive to a corresponding number of primary coil voltage signals to produce digital pulses indicative of reflected spark events from the various secondary coils to the respective primary coils of the ignition system. A number of level shifting circuits are also included and provide a pulse width circuit with a corresponding number of level-shifted primary coil voltage signals. A pulse width circuit is responsive to the number of level-shifted primary coil voltage signals to produce appropriate digital pulses timed to match the non-zero voltage times of the various primary coil voltage signals.

Abstract: A method and an arrangement for detecting combustion misfires in internal combustion engines are presented where a measured ionic current signal is subjected to a floating short-time integration and a feature is formed which corresponds to the maximum value of the floating short-time integrator within the entire measuring window. The window length of the short-time integrator is shorter than the total measuring window and is floatingly displaced over the measuring window.

Abstract: A method is provided for diagnosing a solenoid circuit to determine if the circuit has begun to degrade. By measuring characteristics associated with the electrical waveform, it is determined if the characteristics of a solenoid circuit are different from the previously measured characteristics of the circuit, or of a known functioning circuit.

Abstract: A method and apparatus for testing spark plugs and ignition coils. An apparatus includes a power supply for supplying power to an ignition coil to generate a spark across a spark plug. A capture circuit captures an energy signal reflected from the ignition coil in response to the spark. A comparator circuit compares the captured energy signal to a predetermined signal. A method includes the steps of supplying power to an ignition coil to generate a spark across a spark plug, capturing an energy signal reflected from the ignition coil in response to the spark and comparing the captured energy signal to a predetermined signal. The predetermined signal represents one of a distinct group of reflected energy signals which indicate various defects in the coil or plug. Preferably, a match between the captured energy signal and the predetermined signal is used to indicate to the user a defective coil or plug.

Abstract: An inductive ignition apparatus for a combustion engine includes a measurement device for ascertaining the ionization current at the spark plug of each cylinder, and includes for each spark plug an ignition coil device which forms the ignition high voltage, operates on the transformer principle, and has a primary and a secondary winding, and through whose secondary winding the ionization current flows. A switch is provided which short-circuits the primary winding for the duration of the ionization current measurement.

Abstract: An apparatus for measuring ignition charge signals produced by coils of coil-on-plug devices of an internal combustion engine. A signal detector comprises an insulating substrate having a first conductive planar layer on a first side and a second conductive planar layer on a second side. The first layer is coupled to a signal wire and the second layer is coupled to a ground wire. When the signal detector is held in close proximity to the coil of the coil-on-plug, ignition signals generated by the coil and passing to the plug are detected. The detected signals may be coupled to a signal analyzer for display and analysis. The amplitude of the signal that is output by the signal detector may be adjusted to different coils having different output signal strengths by modifying the ratio of the surface areas of the first layer and the second layer.

Abstract: An ignition coil with an isolated internal lead in proximity to the secondary side can be used in a capacitive discharge ignition system with a microprocessor-based signal-processing module to monitor system performance. The diagnostic lead is fed into a diagnostic signal interface circuit that provides a logic edge to the microprocessor when the spark plug fires. By measuring the time from the firing signal provided by the microprocessor to the logic edge provided by the diagnostic signal interface circuit, the precise energy necessary to fire the plug can be determined. An ignition system that includes an ignition coil with a diagnostic lead can extend spark plug life by automatically adjusting spark energy to minimize wear on the spark plug.

Abstract: The invention relates to an inductive ignition apparatus for a combustion engine, having a measurement device for ascertaining the ionization current at the spark plug of each cylinder, and having for each spark plug an ignition coil device which forms the ignition high voltage, operates on the transformer principle, and has a primary and a secondary winding, and through whose secondary winding the ionization current flows. According to the present invention, a switch (S1) is provided which short-circuits the primary winding (L1) for the duration of the ionization current measurement.

Abstract: A compression sense ignition system includes a sensing capacitor having a conductive sensing element disposed in proximity to the secondary winding leads of a first and a second ignition coil for developing a compression sense ignition signal. Epoxy potting material encapsulates the leads and the sensing element to reduce variation of the effective capacitance of the sensing capacitor. The compression sense ignition signal is processed to generate a cylinder identification signal which is used to determine absolute engine position. A fault mode detection and correction scheme is implemented wherein a controller responsive to the cylinder identification signal can determine correct absolute engine position notwithstanding the occurrence of one or more engine or ignition system faults which may impair the cylinder identification signal.

Abstract: A failure of a detecting circuit such as an ion current detecting circuit for detecting a combustion condition of an engine can be diagnosed at a stage for detecting a combustion condition by a combustion condition detecting apparatus equipped with a malfunction diagnosing apparatus. The engine combustion condition detecting apparatus equipped with the malfunction diagnosing apparatus is arranged by a sensing circuit for sensing an ion current flowing through a combustion chamber, a misfire judging means for judging misfire occurred in the engine in response to the detection signal derived from the sensing circuit, and a malfunction judging means for judging malfunction of the sensing circuit.

Abstract: An improved system and method for detecting solenoid-related faults in a solenoid-controlled actuator assembly. The system includes a processing circuit which controls a solenoid driver circuit for energizing and de-energizing the solenoid, a current sense circuit for sensing the current in the solenoid, and a power supply switching circuit for selectively connecting and disconnecting a supply voltage from the solenoid driver circuit. The processing circuit implements fault detection logic wherein the processing circuit senses the current in the solenoid and, if the sensed current exceeds a predetermined current value for a predetermined time period, disconnects the supply voltage from the solenoid driver circuit and measures the rate of voltage decay in the solenoid driver circuit to determine if an open circuit fault or a short circuit fault exists.

Abstract: An ignition secondary sensor is provided which is disposed in a high voltage path between an ignition coil and a spark plug for use with a detecting circuit for detecting ignition current and ion current flowing through a spark plug. The sensor comprises an ignition path connected in series with the high voltage path and having a pair of reverse current preventing diodes and a detection path connected to a spark plug side end portion of the ignition path and having a pair of current detecting diodes. A path portion of the detection path on the side of the current detecting diodes opposite to the ignition path and a path portion of the ignition path connecting between the reverse current preventing diodes are capacitively coupled. The detecting circuit is connected to the sensor for detecting the ignition current (ignition timing) on the basis of current flowing into the sensor therefrom and the ion current (combustion timing) on the basis of current flowing from the sensor thereinto.

Abstract: The primary-side voltage profile of an ignition voltage is converted into an analog current through the use of a first regulating circuit, whose output voltage is compared with a first comparison voltage in a first comparator. The output voltage is compared with a second comparison voltage in a second comparator. A diagnostic signal for the ignition switch can be tapped at the output of the first comparator, and a measurement signal for the burning duration can be tapped at the output of the second comparator.

Abstract: A combustion state detecting apparatus for an internal combustion engine is imparted with facility for determining discriminatively the causes for non-occurrence of combustion.

Abstract: An ion current detection device is disclosed that is designed to hold an ion current output voltage within a prescribed limit to ensure proper operation of a processing device connected to the output side thereof, while, at the same time, shortening the decay time of the LC resonance associated with an ignition coil. An ion current flows from one end of a capacitor and back to the other end thereof passing through an ignition coil secondary winding, a spark plug, an ion current detecting resistor, and a load resistor. A voltage equal to -(ion current value).times.detecting resistor value appears at a node between the ion current detecting resistor and the load resistor. This voltage is inverted by an inverting circuit and supplied as an ion current output to the processing circuit.

Abstract: The present invention relates to the monitoring of current drawn by an ignition coil for a spark ignition engine, and in particular to circuitry and a method for detecting a malfunction in the charging of an ignition coil or its associated drive circuitry. The electronic circuit comprises: circuitry to measure the voltage of a battery (VB) for charging the coil; software (52) to determine according to the measured battery voltage (VB) a nominal dwell time (TC) for charging fully the coil prior to discharge of the coil; circuitry (32,34) to measure an amount of current drawn by the coil over a time less than the time taken to charge fully the coil; software (36) to extrapolate from the measured current a calculated expected dwell time TD to charge fully the coil; and a device to indicate an error condition (44,62,64,66,68) if the difference (44) between the expected (TD) and nominal (TC) dwell times is beyond a predetermined error limit (58,60).

Abstract: An ion current detection apparatus for an internal combustion engine includes a voltage limiting device for limiting an amount of counterelectromotive force of a primary coil of ignition coil applied to switching elements, a capacitor for applying an ion current detection voltage to a spark plug, and an ion current detection circuit for detecting an ion current wherein the capacitor is connected to the voltage limiting device.

Abstract: An ion current detection device of an internal combustion engine includes a detection voltage generation device which applies a voltage to an ignition plug to generate an ion current in a cylinder of the engine. A current to voltage conversion circuit detects and converts the generated ion current to a voltage signal. A bandpass filter extracts an ac component within a specified frequency range from the voltage signal produced by the current to voltage conversion circuit. An ion current threshold detection portion produces an ion current detection signal when the detected ion current exceeds a predetermined threshold current. A filter characteristic control circuit controls the characteristic of the bandpass filter to suppress the sensitivity of the filter for a predetermined period of time right after the ion current detection signal is detected and, after the predetermined period of time, increase the sensitivity of the filter for detection of the ac signal with the specific frequency.

Abstract: An inductive coil ignition system for an engine, having at least one ignition coil which includes a primary winding fed from a voltage source and having two terminals, and a secondary winding also having two terminals. A switching apparatus is arranged parallel to the primary winding and connects the two terminals of the primary winding as a function of a control signal. An activation circuit generates the control signal.

Abstract: A failure of a detecting circuit such as an ion current detecting circuit for detecting a combustion condition of an engine can be diagnosed at a stage for detecting a combustion condition by a combustion condition detecting apparatus equipped with a malfunction diagnosing apparatus. The engine combustion condition detecting apparatus equipped with the malfunction diagnosing apparatus is arranged by a sensing circuit for sensing an ion current flowing through a combustion chamber, a misfire judging means for judging misfire occurred in the engine in response to the detection signal derived from the sensing circuit, and a malfunction judging means for judging malfunction of the sensing circuit.

Abstract: A measuring circuit for sensing ionization within a combustion chamber of an engine is arranged in the grounded end of the secondary winding (5) of an ignition coil (2), and includes a voltage source for measurements having a substantially constant potential. The voltage source for measurements used is a capacitor 13 which is charged by the spark current SC, and subsequently after the ignition spark goes out will apply a bias voltage over the spark plug gap 3 with a reversed polarity in relation to the spark voltage. The ionisation within the combustion chamber is detected with a measuring resistance 14 arranged in series with the capacitor 13. A rectifying element 11 is connected in parallel with the measuring resistance, which will secure that the spark current is developed in the spark plug gap 4 and that the measurement current passes through the measuring resistance 14. The rectifying element is grounded with a separated ground strap which does not pass the ground plane of the measuring resistance.

Abstract: An ignition system for internal combustion engines, which have means for detecting the secondary voltage transformed to the primary side of an ignition coil, the signal detected by these means being fed to an evaluation device. The evaluation device determines the damping of the voltage signal after the end of sparking, this damping representing a measure for the magnitude of the shunt resistance on the secondary side.