Abstract: A communication bus test tool for motor vehicles having a plurality of electronic modules connected to a common communication bus in a body controller by a wiring harness. The wiring harness has an individual bus signal wire for the bus signal for each electronic module and at least one connector for connecting to a corresponding connector of the body controller. The wiring harness's connector has an individual terminal connected to each individual bus signal wire and the body controller's connector has terminals corresponding to the wiring harness' connector terminals. The bus test tool has a first connector for connecting to the wiring harness's connector with individual terminals corresponding to the individual terminals in the wiring harness connector including individual bus terminals corresponding to the terminals in the wiring harness connector connected to the bus signal wires.

Abstract: A combustion monitoring apparatus for an internal combustion engine is provided which is designed to distinguish abnormal combustion conditions from a normal combustion conditions using a combustion ion current included in a current flowing through plug electrodes of a spark plug, resulting from motion of ions between the plug electrodes which are produced by combustion. For example, if a maximum value of the combustion ion current during one combustion cycle is smaller than a given value, it is determined that a misfire has occurred. If an attenuation time from generation of the current flowing through the plug electrodes until a variation in the current is decreased to a given value is shorter than a given time period, it is determined that a flame has been blown out before combustion is completed.

Abstract: An ion current in the combustion chamber of an internal combustion engine is measured by using the spark plug as an ion current sensor. The ignition circuit arrangement has an ignition coil or transformer with a primary winding forming a primary circuit and a secondary winding forming a secondary circuit in which the spark plug is connected. A measuring voltage is applied to the secondary circuit by circuit components forming a measuring circuit for measuring the ion current. The measuring circuit provides a measuring voltage at a value that is lower than the battery voltage of the ignition system or corresponds to the battery voltage at most. A rectifying element is connected to the secondary circuit which feeds the secondary or ignition current into the battery circuit of the ignition system while an ion current caused to flow by the measuring voltage applied to the secondary circuit is measured between sparking times when no ignition current is flowing.

Abstract: In a keyless entry control apparatus having a fault diagnosis unit provided separately from a car and a keyless entry C/U, the fault diagnosis unit transmits a signal to each control unit connected to a communication line, and when receiving a communication enabling signal transmitted from the keyless entry C/U, the fault diagnosis unit can communicate with the keyless entry C/U. In the case where ID codes are entered in the keyless entry C/U, a signal for setting the keyless entry C/U to ID entry mode is transmitted from the fault diagnosis unit to the keyless entry C/U. The keyless entry C/U which received the signal is set to ID entry mode, and transmits entry information of the ID codes entered in an EEPROM to the fault diagnosis unit immediately. The entry information is displayed on a display device of the fault diagnosis unit.

Abstract: An combustion state detecting apparatus for an internal-combustion engine is equipped with: an ignition coil (4) for applying a high voltage (V2) for igniting to the spark plugs (8a through 8d) of the cylinders of an internal-combustion engine; an ionic current detecting circuit for applying a bias voltage (VBi) to at least one spark plug to detect ionic currents (ia, ib) flowing via the spark plug which has just been subjected to ignition control; comparator circuits (14a, 14b) which compare detected ionic current signals (Eia, Eib) with threshold values (TH1, TH2) and turn them into ionic current pulses (Gia, Gib); and an ECU (2A) which drives the ignition coil according to a crank angle signal (SGT) and determines the combustion state of the internal-combustion engine. The ECU changes the threshold values for each ignition control and judges the combustion state according to the respective threshold values and the state in which the ionic current pulses are generated.

Abstract: A hand-held ignition voltage tester for detecting voltage on a spark plug wire in an ignition system, such as a distributorless ignition system. The tester includes a housing, positive and negative power cables and a capacitive probe for capacitively coupling to the spark plug wire. The capacitive probe generates a voltage signal which is representative of the voltage on the spark plug wire. A plurality of voltage level indicators are mounted to the housing to form a bar graph, with each indicator corresponding to a selected voltage level. A measurement circuit is coupled to the power cables and the capacitive probe for activating the voltage level indicators in response to the voltage signal.

Abstract: A timing light adapter includes first and second light transmissive channels. The first light transmissive channel injects light into an engine case and illuminates a timing mark therein. The second light transmissive channel carries light reflected from the timing mark out of the engine case. The timing light adapter thereby isolates a body of oil within the engine case while allowing visibility of the timing mark without light energy interference from a timing light source.

Abstract: The quality of a fuel-air mixture shall be evaluated by a process and a device during a phase of combustion, especially in a spark ignition engine, in order to make possible a low-emission, fuel-saving and knock-free operation. An electrical testing pulse P is sent for this purpose to the spark plug during the phase of combustion V following the ignition pulse Z. The effect of the actual fuel-air mixture of the combustion chamber on the testing pulse is detected and evaluated as an electrical variable.

Abstract: An apparatus for detecting pressure in an engine cylinder comprises a cylinder pressure sensor inserted between an ignition plug screwed into an engine cylinder head and a bearing surface on which the ignition plug is mounted. The sensor outputs a detection signal depending upon a change in the sensor load corresponding to a change in the pressure in the cylinder, to detect the pressure in the cylinder based on a detection signal from the cylinder pressure sensor. The detection signal from the cylinder pressure sensor is invalidated for only a predetermined period based on an ignition signal that controls the ignition of the ignition plug so that the S/N ratio in the sensor output will not be deteriorated by the ignition noise.

Abstract: An apparatus for reliably conveying real time shaft position information, without cables, between a stationary sensor connected to a reciprocating engine or compressor, or other rotating machinery, and an engine analyzer, in the presence of high energy ignition voltages employs a combination of conventional and non-conventional radio frequency technologies and digital signal processing to both encode and accurately reproduce real time shaft position information. The apparatus provides a safer and more efficient method for an engine maintenance technician to make predictive maintenance measurements on reciprocating engines.

Abstract: An ion current detector device for an internal combustion engine, including: a spark plug having a metallic shell in which a tubular insulator is disposed, a center electrode extending in an axial direction of the tubular insulator and having a front end, a ground electrode which forms a spark gap (G1) with the front end of the center electrode, and at least one slanted bore provided in the metallic shell which is slanted inwardly against the axial direction with respect to the center electrode. An ion current detector electrode is provided within the slanted bore of the metallic shell and located proximate to the front end of the center electrode of the spark plug so as to form an ion current gap (G2) therebetween, the ion current gap (G2) being dimensionally wider than the spark gap (G1), and the spark plug being connected to an ignition circuit to be provided in a cylinder of the internal combustion engine.

Abstract: An apparatus for testing an internal combustion engine is disclosed. The apparatus comprises a probe for electrical connection to at least one spark plug wire of the engine being tested. A peak hold circuit operates to store a representation of a peak firing voltage of the rectified secondary ignition signal and attenuates the stored representation at a predetermined rate over time to enable measurement of peak firing voltage. The testing apparatus is connected to a voltmeter to display a value of the peak firing voltage. Alternatively, the testing apparatus includes a display for displaying the value of the peak firing voltage. Preferably, the testing apparatus is housed in a housing of a size to be held in a user's hand, with a power supply contained therein.

Abstract: A detector for detecting a secondary voltage supplied to a spark plug of an engine comprises a rubber tube mounted on a high tension cord and equipped with a detecting electrode, and a shield case or shield layer enclosing the rubber tube. The rubber tube is made up of first and second semicylindrical rubber members joined together into a tubular shape. The detecting electrode is U-shaped and has a middle portion embedded in the first rubber member and left and right ends which project, respectively, from left and right joint surfaces of the first rubber member, and are sheathed in grooves in left and right joint surfaces of the second rubber member. A lead wire is connected to one of the left and right projecting ends of the detecting electrode. This structure of the secondary voltage detector can facilitate the production process.

Abstract: A pressure transducer suitable for use in measuring the pressures created by the combustive events that occur in internal combustion engines. The transducer utilizes the magnetostrictive effect to measure stress waves present in magnetized metallic components associated with sparkplug devices typically placed in apertures into internal combustion engine cylinders. The present invention includes a replacement sparkplug device that incorporates a pickup coil for measuring magnetostrictive events within the magnetized metal components of the sparkplug device and alternatively a sparkplug boot cover that separately incorporates a removable pickup coil for measuring the stress waves. In either embodiment, the present invention utilizes the magnetostrictive sensor signals measured as a basis for identifying internal combustion cylinder pressures and for identifying the characteristics of the ignition events within the cylinder.

Abstract: A portable apparatus is provided for testing an engine control system of a reciprocating engine. The apparatus includes a processor for generating a simulated waveform of an at least one engine position sensor and a connector for operably coupling the selected waveform to the engine control system.

Abstract: A compression detection apparatus for determining which one of a pair of phase-opposed cylinders is under compression has a capacitive probe coupled to both ends of the secondary winding of an ignition coil servicing both spark plugs of the pair of cylinders. Phase and magnitude of the voltage signal appearing on the capacitive probe line are processed by a single comparator for determining which on of the pair of cylinders is under compression.

Abstract: An internal combustion engine misfire sensing circuit comprises an ion current sensing circuit for sensing an ion current in the combustion chamber of an internal combustion engine, a current/voltage conversion circuit for converting the sensed ion current into a voltage and a waveform shaping circuit for shaping the waveform of an output of the current/voltage conversion circuit. The waveform shaping circuit includes a second comparator for comparing a voltage of a third capacitor with first and second reference voltages for outputting a misfire sensing signal and a capacitor charging/discharging circuit for charging the third capacitor in response to the rising up of an output of the current/voltage conversion circuit and discharging the third capacitor based on the input of the misfire sensing signal. With this arrangement a misfire can be sensed even in an internal combustion engine having multiple cylinders, the number of parts can be reduced as well as the area of circuits can be reduced.

Abstract: An ignition system test instrument used on spark ignited engines includes a housing having a spark chamber. A sleeve with an open and a closed end is slidably mounted over the housing. A compression chamber is formed between the sleeve closed end and the housing. An air passage connecting the spark and compression chambers extends through the housing. The sleeve can be moved relative to the housing, from a lower to an upper position to compress the air in the compression chamber and the spark chamber. A pair of electrodes is mounted to the housing and extend into the spark chamber to form a spark gap. The electrodes are connected in circuit to an engine ignition voltage source. With the spark gap under pressure, the engine can be turned over and the arc (if any) between the electrodes can be observed. A pressure gauge is carried by the housing for sensing and indicating the air pressure in the spark chamber.

Abstract: An engine monitor includes, in a self-contained preferably sealed unit, a spark sensor, inductively and capacitively coupled through the case to a spark pick up wire, a timer, and a running time detector, responsive to inputs from the spark pick up to provide total running time, job time, and service time metering. Preferably, storage means are included for storing maximum RPM and spark mode data, that is, data indicating the number of firings per RPM for the particular engine, as well as a preset service interval and one or more auxiliary timers.

Abstract: An adaptable engine usage meter includes engine monitoring circuitry arranged within a front housing. Three different rear housings can be interchangeably attached to the front housing. A first rear housing includes a concave back portion, so that in conjunction with a complementary concave mounting bracket, it allows the meter to be attached to a round handlebar, such as that on a push mower. A second rear housing is slightly narrower than the front housing, so that a shoulder is formed when they are attached together. The second rear housing allows the meter to be mounted on an instrument panel by fitting it through a cutout until the shoulder engages the panel. When either the first or second rear housing is used, the circuitry in the front housing is connected to the ignition wire and the ground of an engine via a cable extended through the rear housing.

Abstract: An adapter that enables the testing of secondary ignition signals of vehicle engines equipped with wireless secondary ignition systems is disclosed. The adapter detects secondary ignition voltage pulses generated by such an ignition system. It includes an input port coupled to an engine ground for receiving an electrical signal comprising a secondary ignition signal; an output port; and a filter coupled between said input port and said output port, said filter passing an electrical representation of said secondary ignition signal to said output port. In a preferred embodiment, the adapter includes a preamplifier coupled between the input port and the filter to amplify the electrical signal and an amplifier coupled between the filter and the output port to amplify the secondary ignition signal. The output port preferably is coupled to an oscilloscope allowing a technician to visually inspect the secondary ignition system waveform.

Abstract: An inductive pickup sensor employing an isolation transformer to achieve substantially improved immunity to capacitively-induced cross-talk signals is provided. A magnetic pickup coil is coupled to a spark plug wire to receive a spark signal. The spark signal developed across the magnetic pickup coil is then coupled to via a sensor cable to the primary winding of an isolation transformer which is configured to provide a relatively low interwinding capacitance level to substantially reduce the cross-talk signal amplitude relative to the spark signal at a detector circuit. The detector turns the spark signal into a trigger signal at a pair of output terminals.

Abstract: A diesel timing light includes a flash circuit for flashing a xenon lamp in response to ignition events sensed by a knock sensor. A trigger circuit enables the flash circuit only in the presence of an enable signal, which is generated by a sensing circuit immediately before the ignition of the no. 1 cylinder. The sensing circuit includes a visible laser source which illuminates a patch of reflective tape on the engine flywheel just ahead of a timing mark corresponding to engine top dead center. The tape reflects the visible laser light to a sensor which generates the enable signal. The trigger disables the flash circuit immediately after the flash triggered by the first ignition event after the enable signal. LED indicators indicate when the photosensor is detecting the reflected beam and when the knock sensor is detecting ignition events.

Abstract: A system and method for accurately detecting misfires in an internal combustion engine which includes an ignition coil 12 with a primary winding 22 and a secondary winding 30, at least one spark plug 62, and an ignition controller 20 responsive to engine operating conditions for generating an ignition signal. Preferably, the ignition coil generates sparking voltage for firing the spark plug in response to the ignition signal. Sparking voltage and firing of an ignition spark are detected (steps 402-410). An average sparking voltage after the firing of the ignition spark and a peak sparking voltage after the firing of the ignition spark are determined (steps 412-420). And, an indication of misfire in response to the average sparking voltage and the peak sparking voltage is provided (steps 422-428).

Abstract: Ignition events in a direct ignition system are sensed by capacitively coupling positive and negative ignition voltages generated by the secondary winding of the ignition transformer. A pair of planar conductive plates disposed remote from each of the secondary winding leads capacitively couple the ignition voltages to a common node to provide an input to a processing circuit for determination of absolute engine position. The secondary coil and leads are at least partially immersed in an epoxy potting material, which forms a dielectric through which the conductive plates are capacitively coupled to the respective coil leads. The plates are electrically coupled by a conductor to form a common node, which in turn is electrically coupled to a signal processing circuit. Conveniently, the plates and conductors are formed as a single leadframe element and insert molded in the polyester material.

Abstract: In a spark plug voltage probe device which detects a voltage applied to a spark plug installed in an internal combustion engine so as to analyze a burning condition in the internal combustion engine on the basis of the voltage applied to the spark plug, a rubber clamper (9) is secured to the internal combustion engine, and having a groove (92) in which a spark cable (60) is located so as to form a static capacity between the rubber clamper (9) and the spark plug cable (60). An electrical conductor (93) is embedded in the rubber clamper (9) along the groove (92) while the electrical conductor (93) is connected to a microcomputer by way of an output cable (64) so as to analyze a spark plug voltage waveform. A condenser (42) is connected to a common point (A) between the electrical conductor (93) and the microcomputer so as to reduce the spark plug voltage according to a capacity of the condenser (42).

Abstract: In a sparkplug voltage probe device in use for an internal combustion engine, an insulator base is attached to the internal combustion engine, an upper surface of the insulator base having a plurality of grooves in which the sparkplug cables are placed. An insulator sheet is embedded in the insulator base. An electrode layer is provided on an upper surface of the insulator base along the grooves to form a static capacity between the electrode layer and the sparkplug cables when the voltage is applied across the spark plugs. On a lower surface of the insulator sheet an electrical shield layer is provided connected to the internal combustion engine by a ground wire. A lead wire electrically connects the electrode plate to a microcomputer so as to analyze the engine burning condition based on the static capacity between the electrode plate and the sparkplug cables.

Abstract: An apparatus for diagnosing the presence and location of faults within a vehicle's electrical system includes a signal generator for generating an a.c. test signal; a switching circuit connected to an interface between the system's ECU and the system's components for selectively and sequentially applying the a.c. test signal into each electrical lead therein; and a first detector connected to the system's common ground for detecting the system's response to the applied signals, thereby obtaining a set of transitory characteristics for the vehicle's electrical system.

Abstract: In combination, a gas turbine engine ignition system exciter, an igniter, a conductor that connects the exciter to the igniter to form a discharge circuit, and a current pulse detector for detecting current pulses in the circuit, the detector comprising a wire disposed in close proximity to a current carrying element in the circuit so that a sense current is induced in the wire across a coreless gap; the detector further comprising a signal conditioning circuit for converting the sense current to an output that indicates occurrence of a spark discharge.

Abstract: Apparatus for detecting and displaying the revolution speed of an internal combustion engine having an electrical distribution system including at least one spark plug includes a hand held housing having a digital display. An antenna is connected to the housing which is for placement adjacent to the spark cable. A pulse to direct digital interphase circuit is in the housing and counts the electrical energy pulses received by the antenna from the spark cable within a predetermined time frame to determine electrical pulse frequency and to convert the determined electrical pulse frequency into internal combustion engine revolution speed and to display the internal combustion engine revolution speed on the digital display.

Abstract: An apparatus for identifying the power stroke of a particular cylinder in a multi-cylinder engine which utilizes a wasted spark electronic distributorless ignition system but lacks a camshaft driven cylinder identification sensor, wherein a single sensor can be placed in a coil pack adjacent to and substantially equidistant from the ignition coil towers. The sensor will produce a signal reflecting the difference in voltage drops between corresponding pairs of spark plugs who share the same coil and which utilizes this signal to determine the power stroke of individual cylinders to produce a resulting synthetic cylinder identification signal. This apparatus can further be used as a permanent on-board sensor, thereby negating the need for a separate camshaft driven sensor, to determine the cylinder identification.

Abstract: A diagnostic tool having a communications interface adapter for flexible diagnostic communications with automotive vehicle electronic devices automatically identifies, when connected to the adapter, the vehicle type associated with the adapter, and automatically establishes from stored communications information, the diagnostic communications format under which the electronic devices associated with the identified vehicle type communicate. Diagnostic tool communications hardware is then automatically initialized to prepare for diagnostic communications with minimum operator intervention.

Abstract: In a sparkplug voltage probe device, an insulator base is attached to the internal combustion engine, an upper surface of the insulator base having a plurality of grooves in which the corresponding cables are placed. An electrode plate is embedded in the insulator base along the grooves to form a static capacity between the electrode plate and an array of all the cables in the grooves, both of the longitudinal sides of the electrode plate being curled around the outermost cables respectively to compensate shortage of static capacitance so as to form a capacitance adjusting function in order to substantially even a distribution of the static capacity between the electrode plate and the array of all the cables in a direction perpendicular to a length of the electrode plate. A lead wire is provided to electrically connect the electrode plate to a microcomputer.

Abstract: A spark plug cap covering the terminal of a spark plug for an internal combustion engine, made up of an insulative cap body, an ignition coil unit case housing the coil and having a terminal for the ignition coil, a first conductive shaft housed in the insulative cap body for carrying an ignition voltage produced by the ignition coil to the spark plug terminal, and a second conductor located around the first conductor keeping a predetermined distance therefrom separated by the insulative material of the cap body such that a capacitor is formed between the first and second conductors for detecting the ignition voltage.

Abstract: In a spark plug voltage probe device which detects voltage applied to a spark plug installed in an internal combustion engine so as to analyze burning conditions in the internal combustion engine on the basis of the voltage applied to the spark plug, a rubber collar (74) is provided to surround rubber cap (7) secured to high tension terminal (71a) of spark plug (71) so as to form a static capacity between high tension terminal (71a) and rubber collar (74). Electrical conductor (73) is provided between rubber cap (7) and rubber collar (74), and conductor (73) is electrically connected to a microcomputer by output cable (64) so as to analyze the spark plug voltage waveform. Condenser (42) is connected at one end to the ground and the other end to a common point (A) between electrical conductor (73) and the microcomputer so as to reduce the spark plug voltage according to the capacity of condenser (42).

Abstract: High voltage transformer, in particular an ignition coil for a combustion engine, with a conductor section carrying a high voltage with respect to a reference potential (earth) and with at least one conductor surface in the proximity of the conductor section, and galvanically separated therefrom to which a voltage is applied, the variation of which is dependent upon the high voltage. Between the conductor surface (7, 7') and a test output (12) a non-linear electrical transmission element (13) is interconnected.

Abstract: An ignition coil has a capacitor for detecting ignition voltage of a spark-ignition internal combustion engine to determine if misfire occurs. The ignition coil has a primary winding and a secondary winding both wound around a core. A connector section, connected to the secondary winding by a lead, is provided for receiving a high-voltage cable to transmit the secondary winding voltage current to an ignition distributor. These components are embedded integrally in an insulator resin at the time of completing the coil. A conductor is also embedded in the insulator resin such that it is located around the connector section keeping a predetermined distance therefrom and sandwiching the insulator resin, whereby a capacitor, which constitutes a capacitive divider in cooperation with a second capacitor for detecting misfire through the ignition voltage, is formed between the connector section and the conductor. A ceramic insulator can be positioned between the conductor and the connector section.

Abstract: In a snap-in type spark plug voltage probe device, the insulator base has an upper half and a lower half, both ends of which are integrally connected by means of a flexible portion. The upper half and the lower half have a plurality of grooves in which spark plug cables are placed. The upper half and the lower half are joined together by the flexible portion when in a closed position. The upper half has an opening to receive a protrusion provided on the lower half of the insulator base to maintain the upper half of the insulator base along the grooves, providing static capacity between the electrode layer and the spark plug cables when voltage is applied across the spark plugs. A lead wire electrically connects the electrode layer to a microcomputer so as to analyze the burning condition based on the static capacity between the electrode layer and the spark plug cables.

Abstract: A spark plug voltage waveform detector probe for use in an internal combustion engine and which is mounted on a secondary circuit of an ignition circuit to form static capacity therebetween so as to detect a spark plug voltage waveform. The detector probe includes an insulator body and an electrode plate which is embedded in the insulator body and electrically connected to a lead wire. A pair of readily replaceable insulator plates are located under the insulator body each of the insulator plates having at least one groove, the at least one groove of each of the insulator plates opposing each other and cooperating to form an opening in which a spark plug cable is placed which is extended from the secondary circuit. Electromagnetic shield plates are provided to liquid-tightly sandwich the insulator body and the insulator plates so as to form a laminated detector probe structure. The electromagnetic shield plates are electrically connected to the internal combustion engine for grounding.

Abstract: An ionization current detector for an internal combustion engine which includes a single ionization current detecting circuit 11 connected to a plurality of ignition coils 1 for detecting an ionization current flowing through at least one of the ignition coils 1 upon combustion of the fuel. Accordingly, an ionization current detector which is simple in organization and inexpensive can be obtained.

Abstract: A device is provided for detecting high-voltage characteristics in an ignition system having at least two ignition coils. The device includes a plurality of first capacitive signal couplers each being disposed on a respective one of the ignition coils for capacitively extracting a voltage signal from the ignition coil. A circuit arrangement is connected to the plurality of first capacitive signal couplers and includes an output, and a signal combiner for combining the voltage signals extracted from the ignition coils and producing a combined voltage signal at the output. A plurality of second capacitive signal couplers each connected between the signal combiner and a respective one of the first capacitive signal coupler provides for potential isolation between the plurality of first capacitive signal couplers and a further portion of the circuit arrangement.

Abstract: A sparking voltage detecting device for an internal combustion engine having an ignition system having at least one secondary side high-tension cord, is mounted on the secondary side high-tension cord, for detecting sparking voltage generated in the engine. A main body formed of an insulating material has at least one through hole formed therein. The main body includes a pair of halves fabricated separately at least in part from each other and abutting each other along a line extending through the center of the main body. The high-tension cord is fitted through the through hole in a liquidtight manner. At least one conductive member is embedded in the main body at a location radially outward of the through hole and spaced from the high-tension cord by a predetermined distance.

Abstract: In a spark plug voltage probe device, an electrically shield casing (301) is provided in which electrical circuit boards (302) are accommodated, the shield casing (301) having an electrically conductive wall (313) connected to the ground. An insulator base (303) is securely attached to an outer bottom of the electrical shield casing (301) and has an electrode plate (332) embedded in the insulator base to be connected to the electrical circuit boards (302). A rubber plate (342) is securely attached to a lower surface of the insulator base (303). A plurality of grooves (333, 341) are provided between the insulator base (303) and the rubber plate (342) to locate the corresponding cables (305) in the grooves (333,341) so as to form a static capacity (C1) between the electrode plate (332) and the cables (305). This makes it possible to reduce a noise level by the ratio of the static capacity (C1) to a static capacity (C2) between the electrically conductive wall (313) and the electrode plate (332).

Abstract: An ignition coil unit for an internal combustion engine for containing an ignition voltage detective capacitor for misfire discrimination, including a core, a primary and a secondary coil wound around the core, and a case housing the core and the primary and secondary coils which is filled with an insulative material. In this unit, a first conductive electrode plate is placed in the case and electrically connected with the output of the secondary coil, and a second conductive electrode plate is also placed in the case in parallel with the first conductive electrode plate while maintaining a predetermined distance therefrom. An insulator is interposed between the first and second conductive electrode plates forming a capacitor that uses the insulator as the dielectric.

Abstract: A secondary ignition voltage peak meter provides an indication of ignition operation. A capacitive sensor picks up secondary ignition voltage, and an inverting amplifier reduces and inverts that voltage to a second signal. The second signal is conducted to first and second signal storage circuits and is respectively stored as third and fourth signals. Signal from the second storage device is provided to a second amplifier and converted to an on-off gating signal. The signal from the first storage device is provided to a first power terminal of a field effect transistor, and the gating signal is provided to the gate terminal. A third storage device is connected to a second power terminal of the FET, and a third amplifier is connected to the third storage device to provide an output which is moved by a capacitor and adjusted by a potentiometer. The output signal is delivered to a display driver, and the display driver converts the signal to a sensible signal of good, fair and poor ignition operation.

Abstract: A method of manufacturing a spark plug cap covering a spark plug for an internal combustion engine, equipped with an ignition voltage detective capacitor having a first conductor housed in a cap body for carrying an ignition voltage produced by an ignition coil to the spark plug and a second conductor located keeping a predetermined distance from the first conductor while sandwiching an insulative material such that the capacitor is formed between the first and second conductors for detecting the ignition voltage. The method comprises separately fabricating said insulative body and a member from the insulative material embedding said second conductor therein and fixing the member at said insulative body such that said detective capacitor is formed. The second conductor may be formed in the shape of a plate to be wound around the cap body.

Abstract: A sensor (10) detects misfires of combustion cylinders in an internal combustion engine by monitoring the exhaust from the engine. The sensor (10) comprises a spark gap (18) to be situated in exhaust from the engine and a transformer assembly (34). The transformer assembly (34) has an ignition transformer (41a) for providing a potential difference between the electrodes (18a, 18b) of the spark gap (18) and a detection transformer (41b) for sensing the occurrence of an arc across the spark gap (18). An ignition pulse shaper (68) provides an ignition pulse to the ignition transformer (41a) upon receiving a trigger signal from an engine control system (66), and a detection pulse shaper (72) monitors the detection transformer (41b) and forwards an arc detection signal to the engine control system (66) upon detecting an arc across the electrodes (18a, 18b) of the spark gap (18).

Abstract: An ignition distributor cap having a first capacitor for detecting ignition voltage of a spark-ignition internal combustion engine to determine if misfire occurs. The ignition distributor cap has a coil contact tower connected to the secondary winding of an ignition coil of the engine, spark plug terminals connected to spark plugs of the engine, and a rotor connecting the coil contact tower to one of the spark plug terminals with a gap to generate an electric path carrying ignition voltage current produced at the ignition coil to the spark plug. In the ignition distributor cap, a conductor is located around the electric path keeping a predetermined distance from the electric path and forming a first capacitor such that the first capacitor constitutes a capacitive divider with a second capacitor for ignition voltage detection between the electric path and the conductor positioned at the coil contact tower or the individual spark plug terminals.

Abstract: A spark plug cap having a capacitor for detecting ignition voltage of an internal combustion engine to determine if misfire occurs. The spark plug cap covers the terminal of a spark plug and has a conductor for carrying ignition voltage current from an ignition coil to spark plug terminals to generate an electronic spark between spark plug electrodes and an insulator surrounding the conductor. In the spark plug cap, a second conductor is located around the first conductor keeping a predetermined distance from the first conductor such that a capacitor, which constitutes a capacitance divider with a capacitor for ignition voltage detection, is formed between the first and the second conductors. A ceramic insulator may be positioned between the first and the second conductors to provide higher insulation property.

Abstract: A self-contained, clip-on engine operating time log comprises a case containing circuitry for monitoring the accumulated operating time of a spark ignition engine. A plastic sensor, rigidly extending from the case, has two semi-cylindrical channels for clipping the time log directly onto an ignition wire of the engine. The sensor and the circuitry detect spark impulses in the ignition wire for determining the operating time of the engine. A liquid crystal display, visible through a window of the case, digitally displays the accumulated operating time.