Abstract: A two-piece spark plug includes an electrically conductive outer housing including a cylindrical member having an outer wall and an inner wall, the inner wall defining a passage through the outer housing, and a plug member releasably coupled within the outer housing and including an axial electrode and an electrically insulating insulator element encircling the axial electrode, the axial electrode having a first end for connection to an electrical source and a second end for connection within a combustion chamber, and the insulator element having a circumferential first groove and adapted to be positioned within the passage of the outer housing such that a gas-tight seal is formed between the insulator element and the inner wall of the outer housing.

Abstract: An ignition coil, spark plug, and pressure sensor for an internal combustion engine are integrated into a single assembly and mounted directly on a plug hole of an internal combustion engine. A hard spark plug shell serves as a magnetostrictive section for pressure detection. A radially polarized biasing magnet is disposed adjacent the spark plug shell thereby generating an initial flux through a sensing winding. The sensing winding is wound about the lower end of the coil case to sense changes in the induction characteristics of the spark plug shell as a result of pressure changes in the cylinder. A first passive method of sensing pressure whereby the flux change due to the permeability change generates a signal voltage in the sensed coil. This voltage is proportional to the time rate of change of pressure which is integrated to produce a cylinder pressure waveform.

Abstract: A method of using a petroleum based fuel in an internal combustion gasoline engine. The fuel has a flash point of at least 100.degree. F. and the fuel is heated, within the engine, to a temperature above 100.degree. F. The heated fuel is introduced into the cylinders in the engine and ignited within the cylinder to start the engine. The heat source is removed after the engine has become warm. In an alternate embodiment, the electrodes of the spark plugs are continually energized until the electrodes are at a temperature above the flashpoint of the fuel. The electrodes of the spark plugs are then energized intermittently and the fuel is introduced into the heated cylinders to ignite the fuel in the cylinders in a selected sequence.

Abstract: A spark electrode assembly and method of assembling same is disclosed. A ceramic housing having a cylindrical passage provides clearance for a conductive metal electrode. The electrode has a tubular body with rod shaped wires inserted at each end, the wires extending outwardly from the tubular body at each of its ends colinearly. During assembly, the wires are crimped into the tubular body in such a manner that the tubular body is deformed outwardly forming bosses. The bosses are of such a size as to cause an interference fit between the tubular body and the housing passage so that the electrode is captured within the housing. An impact force on the electrode forces the tubular body to expand radially outwardly, thereby further engaging the ceramic housing for holding the electrode in the housing. That part of the electrode body that is not in contact with the housing still has ample room to expand within the housing.

Abstract: An arrangement for easily and rapidly replacing a spark plug in a bore of a cylinder head includes a conductive cylindrical body that screws into the bore. It has a tapered internal passage that receives a replaceable plug with a tapered metal outer surface. A resilient sealing ring retained by the plug seals gas tight against the inner passage. An annular groove on the outer surface of the plug receives groove engaging elements or balls mounted in the body to lock the plug securely in position. A sliding locking sleeve surrounds the groove engaging elements and prevents the elements from moving out of the groove in a locked position. The sleeve may be manually reciprocated to an unlocked position in which the elements are free to move out of the groove so that the plug may be easily replaced. A spring biases the sleeve to the locked position.

Abstract: A plurality of ultrasound whistles formed into a ceramic core of a conventional spark plug used in a cylinder of a gasoline combustion engine for greatly improved air fuel mixture prior to ignition. The spark plug with ultrasound whistles provides for increased engine performance and acceleration, improved fuel mileage and an improvement cleaner burning air fuel mixture thereby providing for reduced fuel emissions into the environment. The ultrasound whistles are constructed in the form of whistle holes. The whistle holes are disposed around a circumference of the ceramic core in a spaced relationship and next to the spark plug's electrode. The holes have a depth in a range of 0.032 to 0.050 inches. Also, the whistle holes have a diameter in a range of 0.031 to 0.033 inches. Around the top of the small closed end whistle holes are upwardly extending lips. The upwardly extending lips have a height above the surface of the ceramic core of 0.015 to 0.040 inches.

Abstract: A spark plug (80) having a center electrode (82) with a cylindrical body and having a tip (84) at one end and a terminal (123) near the other end with an insulator (86) extending around the center electrode (82). A ground shield and retainer unit extends around the insulator (86) and includes a threaded portion (88) near one end and a ground electrode (85) near the other end, having a portion thereof aligned with the center electrode tip (84) to form a spark gap, with a sealing portion (92) disposed therebetween for sealing the engine combustion chamber from the outside environment when the spark plug (80) is installed. The ground shield and retainer unit can be formed from two parts (88,90) which are deformed during manufacturing to be in mechanical engagement and securely holding the insulator (86) in place. The spark plug (80) can also have two or more center electrodes (82,84) with two or more corresponding ground electrodes (83,85) projecting from the ground shield (90).

Abstract: An internal combustion engine spark plug provides an overpressure release mechanism to avert engine component damage as a result of hydrostatic lock caused by liquids (typically water) entering the combustion chamber under operating conditions. This spark plug incorporates predictably and adjustably weakened structural zones such that, upon encountering overpressure situations, the central portion of the plug is ejected, generating sufficient flow area to expel gasses and liquids from the combustion chamber and venting the cylinder to the atmosphere. The invention is also useful in the detection and avoidance of damage under conditions of detonation.

Abstract: A spark plug quick release system is provided including a spark plug with an annular detent formed therein. An adapter is provided with a hollow cylindrical configuration having a lower end with a plurality of threaded grooves formed in an outer surface thereof for screwably coupling with a spark plug threaded mount. Next provided is a quick release assembly including a sliding tube slidably situated about an outer surface of the adapter. By this structure, the sliding tube has a lowered orientation and a raised orientation wherein ball bearings protrude from the corresponding circular aperture of the adapter. As such, upon the lowering of the quick release assembly and the insertion of the spark plug within the adapter, the quick release assembly may be released such that the ball bearings engage the annular detent of the spark plug.

Abstract: An internal combustion engine spark plug provides an overpressure release mechanism to avert engine component damage as a result of hydrostatic lock caused by liquids (typically water) entering the combustion chamber under operating conditions. This spark plug incorporates predictably and adjustably weakened structural zones such that, upon encountering overpressure situations, the central portion of the plug is ejected, generating sufficient flow area to expel gasses and liquids from the combustion chamber and venting the cylinder to the atmosphere. The invention is also useful in the detection and avoidance of damage under conditions of detonation.

Abstract: An arrangement for easily and rapidly replacing a spark plug in a bore of a cylinder head includes a conductive cylindrical body that screws into the bore. It has a tapered internal passage that receives a replaceable plug with a tapered metal outer surface. A resilient sealing ring retained by the plug seals gas tight against the inner passage. An annular groove on the outer surface of the plug receives groove engaging elements or balls mounted in the body to lock the plug securely in position. A sliding locking sleeve surrounds the groove engaging elements and prevents the elements from moving out of the groove in a locked position. The sleeve may be manually reciprocated to an unlocked position in which the elements are free to move out of the groove so that the plug may be easily replaced. A spring biases the sleeve to the locked position.

Abstract: A spark plug (11) having a center conductive path (21) with a cylindrical body having a tip (33, 51, 77) at one end and a terminal (23) near the other end has an insulator (41, 45) radially surrounding the center electrode and a substantially cylindrical body with at least first and second diameter sections separated by a shoulder (29). A ground shield (37) surrounds the insulator first diameter section and including near one end a frustoconical section (31) juxtaposed with the insulator shoulder. There is a ground electrode (55, 57, 73) near the other end having a portion thereof (53, 75) aligned with the center electrode tip to form a spark gap. An annular retainer (59) surrounds the insulator second diameter section and including a threaded portion (61) threadedly engaging the threaded portion (17) of a generally cylindrical opening in the head of an internal combustion engine.

Abstract: A double ignition spark plug has a cavity which is evacuated of substantially all gasses. The insulation portion of the spark plug is formed in two steps at a temperature of 800.degree. to 1000.degree. C. where the first sintering step is when the cavity is open and a first conductor is in place, and a second sintering step is effective to close the cavity and fix a second conductor in place. At least the second sintering step is conducted in a vacuum. The completed double ignition spark plug has substantially all gasses removed from the spark gap within the insulator.

Abstract: A sparking plug cap for internal combustion engines which is made of a resin selected from the group consisting of an alloy of polyphenylene sulfide and polyphenylene oxide, polyarylate, polyether imide and a liquid crystalline polymer, which sparking plug cap is excellent in insulation durability at a high temperature, particularly under a high humidity or in the presence of water.

Abstract: An ignition plug having a center electrode tip and a substantially aerodynamically shaped ground electrode mounted coaxial to the center electrode tip. This construction substantially eliminates shielding and increases the ignition presentation and the aerodynamic flow of fuel in the gap and tip area. This provides greater power, increased gas mileage and reduced pollution. A circular ignition presentation is achieved by positioning the ground electrode around the center electrode forming a substantially uniform gap. Sparks will be emitted from the ground electrode to the center electrode throughout the gap. This provides a greater region of ignition thereby igniting more fuel. Conductive coatings are applied selectively to the inner surface of the ground electrode to control the distribution of electron flow about the gap to improve ignition uniformity. The electrode and insulator in the plug tip have decreased abrupt surface contour discontinuities to allow for aerodynamic flow of fuel.

Abstract: An improved igniter and cable connector assembly for turbine engines. An igniter mounting adapter is secured to the engine. The igniter slides into a hole through the adapter and is retained by an enlarged head on the igniter. An annular seal is positioned around a high voltage terminal on the igniter head and a terminal on the cable connector is positioned against the igniter terminal. The cable connector is secured to the adapter, for example, by either a clamp assembly or a coupling nut or a quick release connector. As the cable connector is secured to the adapter, the seal is compressed between the igniter and connector insulators and, optionally, the connector terminal is rotated and pressed against the igniter terminal to establish a reliable electrical contact. The connector and igniter terminals preferably have mating conical or spherical surfaces, one of which may be an annular segment to provide an increased electrical contact area.

Abstract: The apparatus for measuring spark plug ignition current to monitor combustion in an internal combustion engine includes a spark plug having a spark plug housing containing a spark plug insulating body (12), a pin-shaped central electrode located in the spark plug housing, a ground electrode held in the spark plug housing insulated from the central electrode so as to cooperate with the central electrode and a current measuring resistor (19) for measuring an ignition current of the spark plug. The ground electrode is grounded by electrical connection to the spark plug housing (10) via the measuring resistor (19). The ignition can be monitored by measuring the ignition current passing through the measuring resistor, since the ignition current must pass directly and entirely through the measuring resistor, and the combustion occurring can be assessed from the measured ignition current.

Abstract: A spark plug for insertion into a boring in the cylinder head of an internal combustion engine which does not require threads on the spark plug or in the boring of the cylinder head, but rather use a clip and a seal ring.

Abstract: The invention relates to a plurality of spark plugs each being provided with an ancillary ground cable, the ancillary ground cables all being connected to the negative pole of a vehicle battery to provide an additional ground path.

Abstract: A spark plug for use in an internal combustion engine having a insulator with a cylindrical body that surrounds a center electrode. The cylindrical body has a first diameter section separated from a second diameter section by a shoulder. A sleeve that surrounds the second diameter has an integral base that is positioned a fixed distance from the tip of the center electrode by the engagement of a flange on the sleeve with shoulder on the cylindrical body. A radial tab that extends from the sleeve is located in a slot in a head on a combustion chamber of an internal combustion engine to establish the position of a ground electrode defined by the base in the combustion chamber. An end nut that surrounds the first diameter and engages the flange to locate and position the spark plug within the combustion chamber.

Abstract: An internal combustion engine includes a cylinder head and a spark plug assembly adapted to be received in a cylinder head bore. The spark plug assembly includes a metal ground electrode element having an annulus disposed on a transverse annular seat of the cylinder head bore and a ground side electrode extending from the annulus. The ground side electrode is received in an axial slot of the cylinder head bore between the seat and a cylinder head inner wall and protrudes into the combustion chamber. The orientation of the ground electrode relative to the cylinder head, and thus to the geometry of the combustion chamber, is established by the circumferential location of the axial slot relative to the bore. The spark plug assembly also includes a center electrode element having a center electrode and surrounding insulator body.

Abstract: An ignition amplifier device for the secondary circuit of an ignition system comprises the series connection of a spark gap having an electrode spacing of between 0.05 and 0.2 mm with a condenser. The so formed series connection is shunted to the electrodes of the spark plug.

Abstract: A process and device for indexing and storing electrode oriented spark plugs for use in internal combustion engines where the ground electrode position is critical to engine performance.

Abstract: A power supplementing system for an engine utilizes the selective delivery of electrical charge to a plate in the vicinity of a driving member of the engine, e.g. a piston, to increase the power of the engine. A high voltage AC signal is generated from a lower voltage DC signal by chopping the DC signal and applying it to a step-up transformer. The output of the transformer is rectified and stored in a capacitor. Through the use of cams or actuators on the crankshaft of the engine the charge is applies to the plate so as to attract or repulse the piston at the proper time to supplement its motion.

Abstract: The invention relates to a pressurized ignition system for an engine. The service life of the igniter for the engine and high altitude operation of the engine are substantially reduced due to arc-over between the terminal of the igniter and the metallic shell of the igniter or the nearest ground. The service life of the igniter and associated components are affected by the hot, contaminated environment in which they operate. The present pressurized ignition system includes a chamber around at least a portion of the igniter and the chamber pressurized to a value of, for example, about two atmospheres for suppressing arc-over. The chamber is pressurized by an air compressor drivingly connected to the engine with the air cooled by an engine aftercooler. Pressurizing the chamber prevents contaminates from entering or collecting in the chamber and affecting operation of the system.

Abstract: The invention relates to an ignition system in which a parameter of the charge in a cylinder prior to ignition is measured in order to predict the burning characteristics of that charge and the timing of the spark for igniting that charge in the same cycle is varied in dependence upon the measured parameter in such a sense as to reduce cycle to cycle variations in the engine output torque. A hot film anemometer integrated into the spark plug provides a measurement of the charge velocity, this being one parameter which can predict the burning rate of the charge.

Abstract: A spark plug having a heat pipe located between the insulating core and the shell in the skirt portion thereof to vary the heat range automatically in response to the operating conditions of the engine in which it is fitted. The heat pipe is charged with a non-condensible gas and a working medium that undergoes a phase change at a predetermined design temperature to transport heat by means of an evaporation-condensation cycle from the firing end of the spark plug to prevent the overheating thereof. Below the design temperature, the heat pipe is thermally non-conducting such that the firing end of the spark plug is allowed to reach a temperature that will burn off combustion deposits that cause misfiring. In one embodiment, the heat pipe is fabricated as a separate integral annular element which is installed in the skirt of the spark plug during the manufacture thereof.

Abstract: Improved apparatus (10) for releasably securing a plurality of non-externally threaded ignition devices (12) in cylinder head bores (29) for facilitating the insertion and removal of the ignition devices therefrom, the apparatus (10) comprising means (20) defining a pair of slots (30) about each bore (29); a retaining member (22) for each ignition device (12) having a bearing surface (44) and a pair of projections (42) receivable in a pair of slots (30); and means for releasably securing the projections (42) in the slots (30) with the bearing surfaces (44) abutting the ignition devices (12) for urging them into their respective bores (29).

Abstract: An ignition system for a stratified charge internal combustion engine is disclosed. The engine has at least one combustion chamber and a fuel injection means effective to inject fuel in a conical spray pattern into a predetermined zone of the combustion chamber for establishing a stratified charge. The system has walls dening a plasma ionizing chamber with an outlet orifice, electrical discharge means to apply an electrical charge across the plasma ionizing chamber causing the contents thereof to be shock heated to an ionized condition and released through the outlet orifice as a jet, and means interrupting the outlet orifice to form said plasma jet into a hollow cone and to direct the conical jet into the zone of the injected fuel.

Abstract: Apparatus senses the temperature in a cylinder of an internal combustion engine. The apparatus comprises a spark plug having a central electrode located on the axis of the spark plug, a ceramic insulator encircling the centrally located electrode, a metal casing encircling the ceramic insulator, and a second electrode extending from the metal casing to a position adjacent to the central electrode. The metal casing has continuous threads formed therein and encircling the metal casing for threaded engagement with corresponding threads of an internal combustion engine. A thermocouple is located within the outer periphery of the metal casing and extends to a position adjacent to the gap between the electrodes. The thermocouple has a temperature-sensing junction adjacent to the gap and which junction is located in the cylinder when the spark plug is threaded with the corresponding threads of the engine. A meter connected with the thermocouple indicates the temperature in the cylinder when the engine is operated.

Abstract: To protect the ignition system against high over voltages upon removal of a load in the high voltage circuit, represented by the spark gap of a spark plug, and a distribution gap of a distributor, an electrically conductive terminal element, such as a flag, a spring biased tab, or a push spring which is connectible to ground or chassis is so located that, when the spark plug cable terminals are connected, the insulator of the spark plug cable terminal will be interposed between the flag and the high voltage terminal which is to be protected.

Abstract: Disclosed are several devices for supplementing conventional fuels (liquid or gas) in internal combustion engines with gaseous fuel supplements. The first device contains means for introducing a stream of hydrogen and/or oxygen gas into the spark gap. The second device contains means for introducing a gaseous fuel supplement into the combustion chamber through the piston. The third and fourth devices both contain means for introducing a gaseous fuel supplement into the venturi.

Abstract: An igniter plug that has the forward insulator 80 connected to the outer electrode 24 by a metal ring 60 which is brazed at 62 to the insulator 80 and welded at 61 to the outer electrode 24.

Abstract: An igniter plug that includes a metal sleeve 10 to retain a central electrode 30 within a ceramic insulator 40 to prevent vibration of the electrode tip 35 during operation.

Abstract: An integral spark plug coil comprising a step-up coil within a canister which canister is mounted to a unique double-walled container. The container fits over the neck of the spark plug and is secured to the shell of the spark plug. An inner ceramic bushing is arranged within a metal sleeve defining the outer wall of the container. The space adjacent the neck of the spark plug is in communication with the exterior of the metal sleeve through the small quenched space defined by the inner diameter of the sleeve and the outer diameter of the ceramic bushing and through ports in the sleeve located generally outward of the terminal end of the neck of the spark plug.

Abstract: An integral spark plug coil comprising a step-up coil within a canister which canister is mounted to an aircraft-type spark plug. The canister is secured to the barrel of the spark plug. A ceramic bushing having a hub-like shape is arranged within a metal sleeve defining part of the outer wall of the canister. The space adjacent the recessed terminal of the spark plug is in communication with ports in the metal sleeve through the small quenched space defined in part by an axial face of the ceramic bushing.

Abstract: A spark plug adapter is provided with a small lower portion adapted to be threaded into the spark plug-receiving bore of an internal combustion engine and an upper enlarged portion adapted to receive the spark plug. Around the spark gap of the spark plug is relatively large chamber which functions together with an axial bore which extends through the lower portion as a preliminary combustion chamber. A relatively thin transverse member is arranged diametrically across the axial bore and functions to divide the combustion products into two separate and substantially equal streams and to impart a turbulence thereto as they pass into the internal combustion engine. If desired, the transverse member may carry a conical member with its apex directed toward the spark gap and its base uniformly spaced from the axial bore in order to direct the combustion products in substantially annular sheet form into the internal combustion engine.

Abstract: A method and apparatus for delivering high electrical energy levels by means of an igniter to an air-fuel mixture within an engine, is disclosed. The method and apparatus utilizes any of a variety of igniters of simple construction in an ignition system powered by an non-DC source to obtain extremely high current excursion peaks and extremely high alternating voltage levels feeding the igniters sequentially with the result of obtaining high intensity and high velocity plasma arcs of ionized matter. Such ionized matter may be subjected to a magnetic field integral with each igniter to substantially increase the energy level of the plasma, visually noting the increase in plasma intensity with audible increase in plasma velocity in an experimental set-up. The plasma generates ozone from the air component of the mixture or in the experimental set-up from the air surrounding the igniter, which ozone materially increases the fuel combustion rate and consequently improves engine operating efficiency.

Abstract: Method and apparatus for reducing the nitrogen oxide component from the oxygen-poor combustion products of a hydrocarbon fuel combustion device, which product would ordinarily contain an undesirable excess quantity of oxides of nitrogen. The method and apparatus include the means for associating gaseous hydrocarbon compounds in said products of combustion at a sufficiently high temperature in a related selected contained volume such that a degree of acceleration of the reduction of oxides of nitrogen is obtained so that the NO is reduced to an acceptable level within a selected reaction time related to said volume which reaction time, volume and temperature are reasonably associated with or present within said combustion device.

Abstract: An internal combustion engine ignition apparatus includes a secondary spark plug having a center electrode to which a high voltage is applied. A cylindrical peripheral electrode surrounds the center electrode and has peripheral openings. Upon the formation of a corona discharge due to the high voltage applied to the center electrode, a strong ionic wind and convection of an air-fuel mixture are produced. The ionic wind causes fuel constituents to be gathered in the vicinity of the peripheral electrode thus preventing production of hydrocarbons due to cooling or quenching of the fuel on the combustion chamber wall. Initial ignition of the air-fuel mixture is by means of a main spark plug. The resultant flames are propagated to the corona discharge portion of the secondary spark plug. The corona discharge is then changed to secondary continuous spark discharge, to thereby positively fire the stratified air-fuel mixture.

Abstract: A spark plug cap is provided for use on a spark plug of an internal combustion engine to intensify sparking across the gap between central and ground electrodes of the plug. The spark plug cap includes a cap body which comprises upper and lower insulating body sections detachably interconnected together. The upper body section is provided with a terminal head adapted to be connected to an ignition current supply cord, while the lower body section with a connector socket for mechanically connecting the cap to the spark plug. A conductor rod extend through the cap body to electrically connect the terminal head with the center electrode of the spark plug. At least one capacitor unit is supported within the cap body and connected in parallel to the spark gap between the plug electrodes. The capacitor unit includes a cylindrical dielectric and a pair of electrodes positioned on the opposite end faces of the cylindrical dielectric.

Abstract: An anti-pollution head construction for internal combustion engines is disclosed in which a storage chamber is formed in the head adjacent the spark plug opening, said storage chamber being in constant communication with the cylinder chamber by passages contained in the head. The storage chamber receives unburnt hydrocarbons during the compression stroke of the engine and returns the unburnt hydrocarbons to the cylinder chamber during the subsequent expansion stroke following combustion. The hydrocarbons mix with the oxides of nitrogen at a temperature of at least 2200.degree. Rankine, thereby reducing the oxides of nitrogen to the equilibrium value. Preferably the storage chamber is annular and is arranged concentrically about the spark plug opening.

Abstract: A spark plug generally similar to standard design including a body member supporting a pair of electrodes to provide a spark gap in the combustion chamber of an internal combustion engine, the side electrode carrying a projecting extension outside the spark gap but still within the flame ignition and combustion zone of the engine so as to provide a reaction member which enhances the action of catalytic agents in the fuel or alternatively incorporated in the reaction member, itself.

Abstract: An improved engine for burning a lean air-fuel mixture includes a main combustion chamber into which the air-fuel mixture is introduced and an auxiliary combustion chamber wherein the air-fuel mixture is initially ignited. A spark plug in the auxiliary combustion chamber has central and side electrodes which define a spark gap. A corona discharge is established in an electrostatic field between the central electrode and a field electrode. The ions in the corona discharge collect on fuel particles in the air-fuel mixture so that these particles are electrically charged and deposited on the field electrode, the walls of the auxiliary combustion chamber, and the side electrode. The fuel particles which come toward the central electrode are electrostatically atomized by the corona discharge and accelerated away.

Abstract: The improved combination of a rotary internal combustion engine and spark plug provides a bore in the engine housing extending from the exterior of the housing into communication with the rotor cavity defined by the housing. The bore has a threaded portion to receive the threaded shank portion of the spark plug and an annular shoulder extending in a plane substantially normal to the longitudinal axis of the bore. The spark plug has a complementary annular shoulder portion extending in a plane substantially parallel to the plane of the shoulder of the bore. The shoulder portion of the spark plug is so located as to engage the shoulder of the bore to thereby position the spark gap end of the spark plug relative to the rotor cavity. An annular channel means is provided adjacent the shoulder of the bore to provide an annular space into which is placed a gasket to prevent fluid leakage through the interstices between the bore and spark plug.

Abstract: A resistor built-in spark plug comprises an insulator formed with an axially extending inner hole, a stem fitted in the upper part of said hole in said insulator, a center electrode fitted in the lower part of said hole, a resistor disposed in the central part of said hole, and copper-glass electrode layers disposed between said resistor and said stem and between said resistor and said center electrode. Said resistor is made by firing and solidifying powder of resistor mixture consisting of 75 to 38 volume percent of main resistor component containing tin oxide and 25 to 62 volume percent of glass powder with softening temperature of 300.degree. to 600.degree.C. Said copper-glass electrode layers are made by firing and solidifying a mixture of copper powder and glass powder with the softening temperature of above 530.degree.C and more than 30.degree.C higher than the softening point of glass in the resistor portion.

Abstract: Apparatus for measuring the temperature of the insulator tip of a spark plug being operated in an internal combustion engine. A thermocouple is embedded in the surface of the insulator tip adjacent the spark gap for sensing temperature. The output of the thermocouple is connected through an electro-optical ignition voltage isolation circuit to circuitry which maintains a substantially constant temperature signal during the time interval that ignition voltage is applied to fire the spark plug. The temperature signal may drive a temperature indicating display or devices such as chart or tape recorders to produce records which may be used in analyzing either operation of the spark plug or combustion.