Abstract: A pressure sensor including a housing extending along an axial line, a diaphragm fixed to a front-end side of the housing, a piezoelectric unit disposed in a hole in the housing and including a piezoelectric element, a transmission member that transmits deformation of the diaphragm to the piezoelectric unit, and a guide member having a through hole extending along the axial line and surrounding the piezoelectric unit in the through hole. (SL/AL)?0.26 is satisfied in the cross section perpendicular to the axial line passing through the piezoelectric element, where SL is the maximum value of the distance in the radial direction between the center of the through hole and the center of the piezoelectric element and AL is the maximum value of the distance in the radial direction between the outside surface of the piezoelectric element and the center of the through hole.

Abstract: A pressure sensor including: a cylindrical casing extending in an axial direction; a diaphragm joined to the distal end side of the casing, extending in a direction intersecting the axis of the casing and deforming in accordance with pressure received on the distal end side; and a sensor section disposed inside the casing and outputting an electric signal corresponding to the deformation of the diaphragm. The diaphragm is provided with a plate-shaped base part and three or more protruding parts protruding from the distal end side surface of the base part toward the distal end side and set apart from each other. The relationships 0.05?H?2.5T and 0.05?(S2/S1)?0.8 are satisfied, where T (thickness), H (length), S1 (area of base distal end surface) and S2 (total area of protruding distal end surfaces) are as defined herein.

Abstract: A pressure sensor including: a cylindrical casing extending in an axial direction; a diaphragm joined to the distal end side of the casing, extending in a direction intersecting the axis of the casing and deforming in accordance with pressure received on the distal end side; and a sensor section disposed inside the casing and outputting an electric signal corresponding to the deformation of the diaphragm. The diaphragm is provided with a plate-shaped base part and three or more protruding parts protruding from the distal end side surface of the base part toward the distal end side and set apart from each other. The relationships 0.05?H?2.5T and 0.05?(S2/S1)?0.8 are satisfied, where T (thickness), H (length), S1 (area of base distal end surface) and S2 (total area of protruding distal end surfaces) are as defined herein.

Abstract: A pressure sensor includes: a diaphragm joined to a front side of a housing via a joint portion; a sensor portion; a connection portion connecting the diaphragm to the sensor portion; and a heat receiving portion disposed at the front side of the diaphragm. When: a minimum value of an area of a minimum inclusion region which is a virtual region, which include a cross-section of a portion from the heat receiving portion to the diaphragm and of which an overall length of a contour become minimum on a cross-section perpendicular to the axial line, is defined as a connection area Sn; and an area of a region surrounded by the joint portion on a projection plane perpendicular to the axial line when the diaphragm and the heat receiving portion are projected onto the projection plane is defined as a diaphragm effective area Sd, (Sn/Sd)?0.25 is satisfied.

Abstract: A pressure sensor including a housing extending along an axial line, a diaphragm fixed to a front-end side of the housing, a piezoelectric unit disposed in a hole in the housing and including a piezoelectric element, a transmission member that transmits deformation of the diaphragm to the piezoelectric unit, and a guide member having a through hole extending along the axial line and surrounding the piezoelectric unit in the through hole. (SL/AL)?0.26 is satisfied in the cross section perpendicular to the axial line passing through the piezoelectric element, where SL is the maximum value of the distance in the radial direction between the center of the through hole and the center of the piezoelectric element and AL is the maximum value of the distance in the radial direction between the outside surface of the piezoelectric element and the center of the through hole.

Abstract: A pressure sensor includes: a diaphragm joined to a front side of a housing via a joint portion; a sensor portion; a connection portion connecting the diaphragm to the sensor portion; and a heat receiving portion disposed at the front side of the diaphragm. When: a minimum value of an area of a minimum inclusion region which is a virtual region, which include a cross-section of a portion from the heat receiving portion to the diaphragm and of which an overall length of a contour become minimum on a cross-section perpendicular to the axial line, is defined as a connection area Sn; and an area of a region surrounded by the joint portion on a projection plane perpendicular to the axial line when the diaphragm and the heat receiving portion are projected onto the projection plane is defined as a diaphragm effective area Sd, (Sn/Sd)?0.25 is satisfied.

Abstract: A pressure sensor includes a tubular housing; a diaphragm which is joined to one end portion of the housing through a fusion zone; and a sensor element which is disposed in the housing and to which pressure received by the diaphragm is transmitted. As viewed in a section which contains the center axis of the housing, a pair of the fusion zones exist, and each of the fusion zones is formed in such an inclined manner that its distance from the center axis increases as it extends from the outer surface of the diaphragm toward the other-end-portion side of the housing.

Abstract: A spark plug includes: an insulator having an axial hole; a conductive member disposed around the insulator; a center electrode disposed inside the axial hole, having a bar shape extending in the axial direction, and located on a rear end side with respect to a front end of the conductive member; a ground electrode forming a spark gap between the ground electrode and the center electrode; and a connection part including a plurality of spokes extending in a radial direction whose inner ends are connected to the ground electrode, and connecting the conductive member to the ground electrode. The connection part includes a joint part that is jointed to an inner surface of the conductive member, and the ground electrode has at least one of a notch and a groove at a position that is different from a position connected to the spokes in a circumferential direction.

Abstract: A plasma ignition device 20 includes a spark plug 100, a DC power supply 210, an AC power supply 220, and a coupling section 300. The coupling section 300 includes a capacitor 320 which electrically connects the AC power supply 220 to the spark plug 100. The coupling section 300 reduces the capacitance of the capacitor 320 in the second ignition mode in which transmission of AC power is halted, as compared with that in the first ignition mode in which AC power is transmitted to the spark plug 100.

Abstract: A method of manufacturing a pressure sensor including a tubular housing having a lid-shaped support plate formed at one end of the housing, a diaphragm, a piezoelectric element for outputting an electrical signal corresponding to pressure received by the diaphragm, and a rod-shaped transmission section for transmitting the pressure to the piezoelectric element. The method includes the steps of accommodating the piezoelectric element into the housing, and fixing the transmission section to the housing through the diaphragm in a state in which a predetermined preload is applied to the piezoelectric element in an axial direction of the housing by pressing the piezoelectric element against the support plate by the transmission section.

Abstract: A pressure sensor includes a tubular housing; a diaphragm which is joined to one end portion of the housing through a fusion zone; and a sensor element which is disposed in the housing and to which pressure received by the diaphragm is transmitted. As viewed in a section which contains the center axis of the housing, a pair of the fusion zones exist, and each of the fusion zones is formed in such an inclined manner that its distance from the center axis increases as it extends from the outer surface of the diaphragm toward the other-end-portion side of the housing.

Abstract: An ignition device (100) includes a power supply (2) for discharge; an AC power supply (3); an ignition coil (41) for generating a secondary voltage in a secondary coil (41B); an ignition plug (1) connected to the secondary coil (41B); an AC electrode (43) electrically connected to the AC power supply (3); a high-voltage electrode (42) located between the secondary coil (41B) and the ignition plug (1); an insulator (44) located between the two electrodes (42, 43); and a second insulator (47) which covers the ignition coil (41) and a capacitor (49) composed of the two electrodes (42, 43) and an insulator (44). The secondary voltage and AC power are supplied to the ignition plug (1) via the high-voltage electrode (42). Thus, excellent ignition performance can be implemented while the occurrence of misfire is restrained.

Abstract: A spark plug having a metal shell, center electrode and a ground electrode. The ground electrode includes an electrode base portion extending from a front end portion of the metal shell toward the front, a bent portion connected at one end thereof to a front end of the electrode base portion and an electrode distal end portion extending from the other end of the bent portion and forming a spark discharge gap with a center electrode. The ground electrode has a base material and a coating layer applied to the base material. The coating layer is formed on at least a front end face and an outer circumferential surface other than a center-electrode-side surface of the electrode distal end portion of the ground electrode. The base material of the ground electrode is exposed at least at a part of the electrode base portion.

Abstract: An ignition system includes an ignition plug, a discharge power supply for applying a high voltage to the gap of the ignition plug, a high-frequency power supply for supplying a high-frequency current to the gap, a matching unit provided between the ignition plug and the high-frequency power supply, and a mixer through which currents output from the two power supplies flow. An oscillation frequency fs (Hz) which maximizes the current flowing between the matching unit and the mixer when spark discharge is generated and an oscillation frequency fo (Hz) which maximizes the current flowing between the matching unit and the mixer when spark discharge is not generated satisfy a relation fs/fo?0.85. Thus, a current whose oscillation frequency is equal to the oscillation frequency fs flows between the matching unit and the mixer when spark discharge is not generated.

Abstract: A technique of improving the life of a spark plug which generates spark discharge and AC plasma. A plasma ignition device includes a power control section which reduces AC power P after generation of AC plasma in an AC power supply period Sa during which the AC power P is continuously supplied to a spark plug within a maintainable power range Rp within which the AC plasma can be maintained.

Abstract: An ignition system wherein creation of misfires is suppressed and excellent ignition ability is realized. The ignition system includes a spark plug; a discharge power source applying a voltage in order to generate a spark discharge at the spark plug; an AC power source supplying AC power to a spark generated by the spark discharge; and an ignition cable electrically connecting the spark plug, the discharge power source and the AC power source. The ignition cable includes a discharge electrode connecting the discharge power source and the spark plug, an AC electrode transmitting AC power from the AC power source to the spark plug, and an insulator interposed between the discharge and AC electrodes.

Abstract: An ignition system that sufficiently utilizes the energy output from a power supply, to thereby realize excellent ignition performance. The ignition system includes an ignition plug having a spark discharge gap formed between a center electrode and a ground electrode, and a power supply for supplying electric energy to the spark discharge gap. Electric energy output from the power supply for producing spark discharge of one unit is set to 100 mJ or greater. S1?[{?30 (mm?1)×G1+60}/100]×S2 and G1<2.0 are satisfied wherein G1 represents the size (mm) of the spark discharge, S1 represents an area (mm2) defined with a region obtained by removing, from a projection region of the center electrode, a region where the projection region overlaps with a projection region of the ground electrode and S2 represents an area (mm2) defined with the projection region of the center electrode.

Abstract: A spark plug having a metal shell, center electrode and a ground electrode. The ground electrode includes an electrode base portion extending from a front end portion of the metal shell toward the front, a bent portion connected at one end thereof to a front end of the electrode base portion and an electrode distal end portion extending from the other end of the bent portion and forming a spark discharge gap with a center electrode. The ground electrode has a base material and a coating layer applied to the base material. The coating layer is formed on at least a front end face and an outer circumferential surface other than a center-electrode-side surface of the electrode distal end portion of the ground electrode. The base material of the ground electrode is exposed at least at a part of the electrode base portion.

Abstract: A spark plug includes: an insulator having an axial hole; a conductive member disposed around the insulator; a center electrode disposed inside the axial hole, having a bar shape extending in the axial direction, and located on a rear end side with respect to a front end of the conductive member; a ground electrode forming a spark gap between the ground electrode and the center electrode; and a connection part including a plurality of spokes extending in a radial direction whose inner ends are connected to the ground electrode, and connecting the conductive member to the ground electrode. The connection part includes a joint part that is jointed to an inner surface of the conductive member, and the ground electrode has at least one of a notch and a groove at a position that is different from a position connected to the spokes in a circumferential direction.

Abstract: A technique for lowering power loss involved in supply of high-frequency electric power to an ignition plug. The ignition plug includes a tubular insulator having an axial bore extending therethrough; a center electrode disposed in the axial bore; a metal terminal disposed rearward of the center electrode in the axial bore, electrically connected to the center electrode, and supplied with high-frequency electric power from an external source; a metallic shell disposed to circumferentially surround the insulator; and a ground electrode electrically connected to the metallic shell and adapted to generate plasma in cooperation with the center electrode through supply of high-frequency electric power to the metal terminal. At least a portion of the inner surface of the axial bore is coated with metal coating. The center electrode and the metal terminal are in electrical contact with the metal coating.