Abstract: A ceramic heater is provided which may be built in a gas sensor to heat a sensor element up to a desired activation temperature. The ceramic heater includes a pair of electrical conductors formed on a ceramic body. Each of the conductors is equipped with a terminal. Leads are joined to the terminals for supplying electrical power to the conductors. Joints between the leads and the terminals are covered hermetically by a seal, thereby minimizing corrosion thereof to avoid disconnections of the terminals from the leads. This improves the durability of the ceramic heater.

Abstract: A ceramic heater is provided which may be employed in a gas sensor. The ceramic heater includes a heating element disposed inside a ceramic body, a connector assembly, and a cover coating. The connector assembly consists of an external terminal, a connector terminal, and a metallic joint layer. The external terminal is affixed to an outer surface of the ceramic body in electrical connection with the heating element. The joint layer is formed on the external terminal to establish an electrical joint between the external terminal and the connector terminal. The cover coating is wrapped over a surface of the connector assembly and made of a metallic material containing a main component of one of Au, Pt, and Cr, thereby ensuring a corrosion resistance of the connector assembly.

Abstract: A ceramic heater is provided which may be built in a gas sensor to heat a sensor element up to a desired activation temperature. The ceramic heater includes a pair of electrical conductors formed on a ceramic body. Each of the conductors is equipped with a terminal. Leads are joined to the terminals for supplying electrical power to the conductors. Joints between the leads and the terminals are covered hermetically by a seal, thereby minimizing corrosion thereof to avoid disconnections of the terminals from the leads. This improves the durability of the ceramic heater.

Abstract: A ceramic heater is provided which may be employed in a gas sensor. The ceramic heater includes a heating element disposed inside a ceramic body, a connector assembly, and a cover coating. The connector assembly consists of an external terminal, a connector terminal, and a metallic joint layer. The external terminal is affixed to an outer surface of the ceramic body in electrical connection with the heating element. The joint layer is formed on the external terminal to establish an electrical joint between the external terminal and the connector terminal. The cover coating is wrapped over a surface of the connector assembly and made of a metallic material containing a main component of one of Au, Pt, and Cr, thereby ensuring a corrosion resistance of the connector assembly.

Abstract: An improved structure of a spark plug which provides higher durability of a joint of a noble metal chip to an electrode such as a center or a ground electrode. The joint is formed by laser welding. A fused portion made of materials of the noble metal chip and the electrode fused together by the laser welding is formed in the joint so that it may continue over at least half a circumference of a contact between the noble metal chip and the electrode without interfaces of welds, thereby enhancing the activity of the fused portion as a thermal stress absorber. A welding method is also provided.

Abstract: An improved structure of a gas sensor is provided which is designed to ensure the reliability of electrical joints between a ceramic heater disposed in a sensor element and connector terminals for supplying electric power to the heater. The connector terminals are joined to lead wires extending outside the gas sensor to a power source. The connector terminals are elastically deformable and fitted on power supply electrodes affixed to the heater to establish electric contacts therebewteen without use of a brazing material. This permits the connector terminals and the power supply electrodes to thermally expand independently of each other when subjected to intense heat, thus resulting in almost no thermal stress on the electric contacts, which ensures the reliability of such contacts in high temperature environments.

Abstract: In producing a spark plug including a central electrode having a first chip including noble metal and an earth electrode having a second chip including the noble metal, a spark gap being disposed between the first and second chips, a chip including the noble metal. The chip is welded to an end of the central electrode and to an end of the earth electrode. The welded chip is cut to form the first and second chips and the spark gap.

Abstract: An improved structure of a spark plug which provides higher durability of a joint of a noble metal chip to an electrode such as a center or a ground electrode. The joint is formed by laser welding. A fused portion made of materials of the noble metal chip and the electrode fused together by the laser welding is formed in the joint so that it may continue over at least half a circumference of a contact between the noble metal chip and the electrode without interfaces of welds, thereby enhancing the activity of the fused portion as a thermal stress absorber. A welding method is also provided.

Abstract: A temperature sensor has a sensing element (13) consisting of a thermistor (11) and leads (12) and a sheath pin (15) containing core wires (14), to accurately detect temperature. A method of manufacturing such a temperature sensor includes the steps of connecting the leads to the core wires, arranging an insulator (130) around the sensing element, filling the insulator with an inorganic adhesive (135) to fix the sensing element in the insulator, arranging a metal cover (16) around the insulator, and joining an end of the metal cover to an end of the sheath pin.

Abstract: A tip holding jig having a receiving hole is placed below an electrode of a spark plug. A noble metallic tip is positioned at least partly in an inlet of the receiving hole. The noble metallic tip is fixed to the electrode by resistance welding under a condition that the electrode presses the noble metallic tip to the jig.

Abstract: In producing a spark plug including a central electrode having a first chip including noble metal and an earth electrode having a second chip including the noble metal, a spark gap being disposed between the first and second chips, a chip including the noble metal. The chip is welded to an end of the central electrode and to an end of the earth electrode. The welded chip is cut to form the first and second chips and the spark gap.

Abstract: A spark plug for use in an internal combustion engine comprises a central electrode made of a base metal and an earth electrode. A tip portion is provided on the central electrode. The tip portion includes a noble metal tip layer for defining a spark discharge gap between the noble metal tip layer and the earth electrode, and an alloy layer provided between the noble metal tip layer and the central electrode. The tip portion is provided with grooves to be divided into a plurality of sections. The tip portion has an outer peripheral wall flared towards the earth electrode, and a width of the grooves gradually increases from a bottom thereof to a surface of the noble metal tip layer for defining the shark discharge gap.

Abstract: A spark plug which realizes reliability against thermal stress even in a case where dissimilar noble metal materials are disposed on the tip portion of the center electrode opposing the ground electrode and which realizes improved productivity while assuring durable reliability. The spark plug includes a center electrode electrically insulated from a housing and having a small-diameter portion at a tip portion which has a diameter smaller than that of a main body of the center electrode and composed of similar kinds of material as the center electrode, and a round-shape material, which is formed into a cylindrical or a ring shape, composed of dissimilar metal material.

Abstract: According to the present invention, a spark plug for an internal combustion engine includes a center electrode, a ground electrode so as to form a spark gap with the center electrode, and a tip electrode composed of a material having a superior consumable resistance as compared to the center electrode and disposed on an end face of the center electrode so as to form a spark gap with the ground electrode. An axial length of the discharge portion of the ground electrode where spark discharge occurs is substantially larger than an axial length of the tip electrode where spark discharge occurs. When used for an internal combustion engine, a spark discharge is mainly generated between the peripheral surface of the center electrode and the ground electrode during early operation. Consequently, as the center electrode has been consumed, the spark discharge is mainly generated between the tip electrode and the ground electrode.

Abstract: A spark discharge tip, such as for a spark plug for an internal combustion engine in which the life of the tip is prolonged. A composite material is formed by bonding a material for a discharge layer, mainly composed of platinum, to a material for a thermal stress relieving layer, which is an alloy mainly composed of platinum, and having a coefficient of thermal expansion between that of the electrode and that of the discharge layer. A composite tip is formed by stamping the composite material into a columnar shape from the discharge layer side so that the periphery of the interface between the discharge layer and stress relieving layer is covered by the discharge layer. The composite tip is then resistance welded to the electrode.

Abstract: There is disclosed a spark plug which can maintain a low spark voltage for a long period of time even if a noble metal tip is used in a small amount. A discharge gap is formed between a central electrode and an earth electrode. The noble metal tip is formed on that end face of the central electrode facing the earth electrode. A cross-shaped groove is formed in that end face of the noble metal tip joined to the central electrode. The cross-shaped groove is exposed when the noble metal tip is consumed by a discharge developing in the discharge gap.

Abstract: A spark plug for use in an internal combustion engine comprises a central electrode made of a base metal and an earth electrode. A tip portion is provided on the central electrode. The tip portion includes a noble metal tip layer for defining a spark discharge gap between the noble metal tip layer and the earth electrode, and an alloy layer provided between the noble metal tip layer and the central electrode. The tip portion is provided with grooves to be divided into a plurality of sections. The tip portion has an outer peripheral wall flared towards the earth electrode, and a width of the grooves gradually increases from a bottom thereof to a surface of the noble metal tip layer for defining the spark discharge gap.

Abstract: A spark plug for an internal combustion engine includes a central electrode, and an earth electrode disposed in opposed relation to the central electrode on an axis of the central electrode to thereby form a spark gap between the central electrode and the earth electrode. The central electrode has a pillar-like portion provided at a distal end thereof disposed close to the spark gap, the pillar-like portion having a predetermined thickness corresponding to an intended lifetime of the spark plug. The central electrode also has a smaller-diameter portion disposed adjacent to a proximal end of the pillar-like portion, the smaller-diameter portion being smaller in diameter than the pillar-like portion. The pillar-like portion and the smaller-diameter portion are interconnected in a step-like manner. A step portion may be provided between the pillar-like portion and the smaller-diameter portion so as to limit the position of a spark discharge.

Abstract: A spark plug for an automotive internal combustion engine providing improved ignition even when carbon is deposited on the insulator of the plug. A rich fuel-air ratio causes carbon to be deposited on spark plug insulators, thereby decreasing its effective insulation. By limiting the geometrical dimension of the plug's center electrode the problem of carbon build-up is overcome. The sizes of these elements have certain allowable ranges that enhance the igniting effect of the plug.

Abstract: A spark plug for an internal combustion engine including a center electrode, an earth electrode, a metal tip joined by welding to an ignition section of at least one of the center electrode and the earth electrode, and an alloy layer located at a welding portion between the metal tip and the at least one electrode. The metal tip is formed of material highly resistant to heat and wear which is distinct in the coefficient of thermal expansion from the material of the electrodes. The alloy layer is formed to have a thickness of at least about 10.mu., so as to avoid the rupture of the metal tip along the surface thereof adjacent to the welding portion.