Abstract: A twin spark ignition apparatus having two high-voltage (HV) outputs incorporates features for balancing load capacitance on each HV output. The ignition apparatus provides a first high-voltage (HV) connection configured for direct mounting on a first spark plug, and a second HV connection for coupling to a second spark plug by way of an HV cable. The HV cable adds capacitance at the second HV output, as compared to a direct mount. The secondary winding is shifted by a predetermined distance, relative to the primary winding, in direction toward the direct mount end of the ignition apparatus. The shifting reduces the internal load capacitance at the second end (top), so that when the capacitance added by the HV cable is considered, the respective load capacitances are balanced. The voltage variation between the two HV outputs is reduced.

Abstract: An ignition coil includes a coil portion that has a primary coil, a secondary coil, and an outer core. The outer core is arranged on a radially outer side of both the primary coil and the secondary coil. A fitting member, which is in a substantially cylindrical shape, has an inner periphery via which the fitting member is fitted to the outer core. A connector case has a fit hole via which the connector case is fitted to an outer periphery of the fitting member. The connector case connects with an axial end of the coil portion via the fitting member. The fitting member includes an embedded member that is at least partially embedded in the fitting member. The embedded member is formed of a material that is different in Young's modulus from a material constructing the fitting member.

Abstract: An ignition coil, which is adapted to being mounted to a sparkplug, includes a coil body having a primary coil and a secondary coil. The ignition coil further includes a plug cap provided to an axial end of the coil body. The coil body is adapted to being mounted to the sparkplug via the plug cap. The plug cap has a plug-fitting hole adapted to being axially fitted to an insulator of the sparkplug. The plug cap has an end surface defining the plug-fitting hole. The end surface includes circumferential portions respectively located at axial positions each being different from each other with respect to a circumferential direction.

Abstract: An ignition coil device mounted on the cylinder head of an internal combustion engine. The ignition coil includes: a cylindrical pipe inserted into a plug hole while a first clearance is formed between the cylindrical pipe and the plug hole; a coil tower arranged over the cylindrical pipe; a seal member arranged below the coil tower for sealing the plug hole; and a cover arranged between the seal member and the coil tower. The seal member is formed with an air bleeding hole extending from the first clearance to a side of the coil tower. The air bleeding hole includes a protruding opening. A circumferential wall portion is positioned on the outer circumference side of the protruding opening while a second clearance is formed between the cover and a periphery of the protruding opening.

Abstract: An ignition device for an internal combustion engine has a spark plug, an ignition coil, a housing and a mounting portion. The spark plug is for discharging a current to ignite an air-fuel mixture in a combustion chamber of the internal combustion engine. The ignition coil is for supplying the current to the spark plug. The housing encloses the spark plug and the ignition coil therein. The housing has a mounting portion to be disposed in a mounting hole provided in a cylinder head of the internal combustion engine. The mounting portion includes a screw portion a non-screw portion. The screw portion is to be screw-fastened to the mounting hole. The non-screw portion is not to be screw-fastened to the mounting hole.

Abstract: An ignition coil is disclosed. The ignition coil includes an insulative material, a body, and a head coupled to the body. A portion of the insulative material is included in the body, and a portion of the insulative material is included in the head. The head includes a casing, a flange for coupling to an engine case, and a connector adapted to be connected to an external device. The head also includes a conducting terminal with a connector pin, an exposed contact, and a connecting part. The connector pin is coupled to the connector, the exposed contact is coupled to the casing or the flange, and the connecting part couples the exposed contact and the connector pin. A portion of the connecting part is embedded in the insulative material, and wherein a remaining portion is embedded in the casing. A method of manufacturing the ignition coil is also disclosed.

Abstract: A plurality of spark electrodes are disposed in an arc shape on the surface or so as to be projected from the surface of an insulating member formed on a part of the wall face of a combustion chamber, and are formed so as to be in series electrically via discharging gaps. A spark plug is provided integrally with an injector, and the spark plug and the ignition coil are integrated. The three members are constructed as an integral unit, thereby improving installability to an engine.

Abstract: A spark plug includes a metal shell, an insulator, a center electrode, a ground electrode, and a terminal fixed to the insulator. The dimensional parameters in the structure of the spark plug, such as a maximum diameter A of the terminal and a diameter B of the insulator satisfy a dimensional relationship defined through experimental investigation. The structure facilitates an attachment of a plug cap to the spark plug.

Abstract: A stick ignition coil apparatus for an ignition plug includes a primary coil arrangement, a secondary coil arrangement, a center core, a coil case, a high voltage terminal, a spring case and dielectric resin. The primary coil arrangement is located radially outward of the secondary coil arrangement, which is located radially outward of the center core. The coil case is located radially outward of the primary coil arrangement. The high voltage terminal is located at a distal end of the secondary coil arrangement. The spring case holds a spring. The dielectric resin is filled in a space defined radially inward of the coil case. An open end of the high voltage terminal is connected to an annular corner portion of a distal projecting portion of a secondary spool of the secondary coil.

Abstract: An ignition terminal assembly including a serpentine conduction element having an end and a formed terminal connected to said end.

Abstract: An ignition device for an internal combustion engine has a primary and secondary coils of an ignition coil, a center and ground electrodes of a spark plug, a cylinder shaped insulator and a cylinder shaped tube. The center electrode is disposed apart from the secondary coil in a longitudinal direction of the ignition device. The insulator is made of an insulating material and has a coil surrounding portion surrounding the secondary coil and a plug surrounding portion surrounding the center electrode. The primary coil is wound on an outer circumferential face of the coil surrounding portion. The ground electrode is disposed on an outer circumferential face of the plug surrounding portion. The tube is made of a magnetic material and has a coil covering portion covering the primary coil and a plug covering portion covering the plug surrounding portion and the ground electrode.

Abstract: Described herein is a coil housing for receiving a plurality of coils for a two-cylinder motorcycle having a plurality of spark plugs and ignition coils. The invention consists of a plurality of coil receptacles conjoined by frame mounting means for attaching the coil housing to the motorcycle such that each coil housing is juxtaposed adjacent a cylinder of the motorcycle. Each coil receptacle defines a cavity having means for retaining a coil and spark plug wires for connection between the output terminals of the coils and the terminals of the spark plugs. When the coil housing is mounted to a motorcycle, the external surface conforms to the corresponding external surface of each of the cylinder.

Abstract: An internal combustion engine ignition device has a resin layer in a clearance between an insulator and a winding contained in the insulator. The ignition device has a cylindrical insulator and a resin layer. The insulator has an opening portion at one end and a bottom portion at the other end. The insulator contains one of a primary winding and a secondary winding. The resin layer is formed by charging a resin in the clearance between the insulator and one of the windings. The diameter of the inner periphery of the insulator gradually increases from the opening portion to the bottom portion. When the resin layer shrinks from the opening portion toward the bottom portion of the insulator, the resin layer can shrink without getting snagged on the inner periphery of the insulator.

Abstract: An ignition unit for igniting propellants having at least one electrically conductive pin with a pin holder comprising a metal ring which encloses the pin by leaving an annular cavity with an insulating filing in the annular cavity. An electrically conductive bridge or a semi-conductor bridge connects between the metal ring and the pin with a sealing cap which is connected to the one face side of the pin holder and which receives the propellant. A plug can be connected in a positive or non-positive way with the metal ring on its end averted from the sealing cap and which enters into an electrically conductive connection with the pin in operation. At least one of the two elements, either the metal ring or the plug are provided with a coating in the region between the mutual connection, which coating has a low electric contact resistance between the plug and the metal ring.

Abstract: An insulator includes a plug side cylindrical portion having an inner space for accommodating a center electrode and a coil side cylindrical portion extending in a direction departing from a combustion chamber. The high-voltage portion of an ignition coil is entirely accommodated inside the coil side cylindrical portion. According to this arrangement, the coil side cylindrical portion can assure insulation between the high-voltage portion and the low-voltage portion. The portion to be insulated and fixed by an insulating resin is limited only to the secondary winding.

Abstract: An integrated ignition apparatus has a coil section and a plug section. The coil section has a spring as a connection member internally. The spring electrically connects other inside terminal members of the plug section. When the coil section and the plug section are integrated, the spring is pressed, and resiliently deforms in the axial direction. Spring-back force of the spring maintains electrical connection steadily, and prevents disconnection of the spring and the terminal members due to vibration. This structure prevents failure in electric conduction between the coil section and the plug section.

Abstract: An axially potted progressive wound remote mount ignition coil (axially potted ignition coil) includes a coil case, at least one coil assembly, and a quantity of potting material. Each coil assembly is progressively wound. The coil case includes a coil cavity for each coil assembly, a primary connector, and two secondary connectors for each coil cavity. Each primary coil is connected to the primary connector and an end of each secondary coil is connected to a single secondary connector. A quantity of potting material is poured over the open end of each coil cavity. A second embodiment of the axial potted ignition coil includes a modular coil case, at least one coil assembly, and a quantity of potting material. The modular coil case includes at least one coil tube, a rear end cap and a forward end cap. Each coil assembly is inserted into a respective coil tube.

Abstract: Internal combustion engine (ICE) on-plug ignition coils with transistor drivers located in powertrain control modules (PCM) or other remote locations are prone to high electrical and magnetic interference (EMI) emissions and are subject to interference from other components due to long connecting wires. Ionization detection circuits have even greater sensitivity to EMI because of their very low signal current levels (mioroampere). The present feature of the invention integrates both the coil driver transistor and ionization detection circuits into the on-plug ignition coil. By placing the circuit on top or on the side of the coil, the connection distance from the circuit to the secondary winding is minimized. Thus, the circuit is less susceptible to electrical and electromagnetic noise.

Abstract: An interesting coil supporting unit for an engine includes an elongated casing and a plurality of coil units. Each coil unit has a coil support portion and an ignition coil. The coil support portions are disposed inside the casing at predetermined intervals. The casing and the respective coil support portions are fastened to a cylinder block by means of a plurality of bolts. In this state, each coil unit is supported by the corresponding bolt so as to be slidable in its radial direction. Therefore, the coil units can be positionally slid in the casing and thereby installed easily on the engine.

Abstract: An ignition coil cassette having bushings retained by an irregularity of the bushings being encased by epoxy. As a result, the process by which the bushings are installed into the ignition coil cassette avoids the cost associated with the overmolding installation process, and further avoids the potential for damage associated with the ultrasonic insertion process. The irregularity is located generally adjacent one end of each of the bushings and may be, for example, in the form of an undercut or a protrusion.

Abstract: An ignition coil assembly includes a base member formed with collars having corrugated faces at the bottom ends thereof. Corresponding bosses are formed on the engine head cover, which also have corrugated faces conforming to those of the collars. When the base member is mounted on the engine, the ribs of one of the corrugated faces are fitted in the ridges of a corresponding corrugated face. When removing the ignition coil assembly from the engine, the relative positions of these corrugated faces are changed so that the ribs of one of the corrugated faces ride up onto the ribs of the other one, whereby the base member is lifted up.

Abstract: An air throttle body assembly having an integrated electronic control unit, ECU, is part of robust and compact electronic fuel injection system of a combustion engine. The ECU has an internal heat sensitive microprocessor located in an environmentally protected inner compartment of the ECU defined between an external surface of thermally conductive throttle body and a circuit board of the ECU. The throttle body has a through air passage for flowing of combustion air into the piston cylinder. The relatively cool and non-laminar flow of air also serves to cool the inner compartment of the ECU through the throttle body thus protecting the microprocessor from overheating. Moreover, a thermally conductive heat sink member of the ECU is exposed within the inner compartment and directly engages various heat producing transistors for transfer of heat by thermal conduction away from internal circuitry an into the surrounding environment outward from the throttle body assembly.

Abstract: An ignition coil includes a connecting device for contacting a spark plug of an internal combustion engine, the connecting device being designed to have a sleeve made of insulating material. The sleeve is able to be connected at a first end section to a high voltage side of the ignition coil, and at a second end section has an accommodation for the spark plug. Furthermore, in the sleeve at least one conductive contact part, touching the spark plug, is situated for the electrical connection of the ignition coil to the spark plug. At the high voltage side of the ignition coil, between it and the spark plug, a plurality of electrically conductive modular components are able to be positioned, which in the installed state are connected in a detachable, electrically conducting manner.

Abstract: An ignition apparatus includes a secondary winding spool having a secondary winding wound thereon. The secondary winding includes a low voltage end and a high voltage end that is configured for connection to a spark plug. The secondary winding at the high voltage end is configured in accordance with a predetermined radial thickness profile taken in the direction from the high voltage end towards the low voltage end. The profile is determined as a function of (1) a reflected voltage associated with the spark gap breakdown of the spark plug and (2) an induced voltage due to magnetic flux coupled through a central core. The profile is determined so as to reduce layer-to-layer voltage levels in the secondary winding near the high voltage end. The profile can be wound or can be molded in the secondary spool itself.

Abstract: A center core 1, a secondary coil 3 wound at a secondary bobbin 2 and a primary coil 5 wound at a primary bobbin 4 are placed concentrically inside a coil case 6 in sequence from the inside of the coil case. One end of the secondary coil 3 is connected to the primary coil side and becomes a low-voltage side, and the other side becomes a high-voltage side due to an induced voltage and used with connection to the individual ignition plugs of the internal combustion engine. The radial thickness of the bobbin at the low-voltage side 3a and the high-voltage side 3c of the secondary coil, each located at the both ends of the secondary coil, is made larger than the radial thickness of the bobbin at the center part 3b of the secondary coil. The radial thickness of an insulating layer 8 between the secondary coil 3 and the primary coil 5 at the low-voltage side 3a of the secondary coil is smaller and the radial thickness of the insulating layer at the high-voltage side 3b of the secondary coil is larger.

Abstract: An ignition device for a personal watercraft engine, which allows mounting of a four-cycle engine on the personal watercraft and prevents occurrence of leakage of current. The engine for driving a jet propelling pump is provided in a watercraft body surrounded by a hull and a deck. A spark plug for spark ignition is provided in a cylinder head of the engine, and an integral cap ignition coil having a water-proof structure is water-tightly provided in the cylinder head in such a manner as to be located on the spark plug at an uppermost portion of the engine. A water-escape groove continuous to a recess for receiving a cap is formed in an upper surface of the cylinder head. A bottom surface of the escape groove is formed into a shape tilted downwardly.

Abstract: Plural ignition coils are inserted into corresponding plug holes. Each coil-head of the ignition coil is received by a holder. The coil-head is pressed by a base plate toward the engine. The holder has hooking claws. The base plate has hooking slots to movably engage with the hooking claws, so that relative position between the ignition coils and the plug holes can be adjusted. In case one ignition coil fails, the disabled ignition coil can be replaced individually. A first connector is formed on the coil-head, and a second connector is formed on the holder. The second connector is connected with the first connector when the holder is engaged with the ignition coil at one time. Thus, assembly work process can be reduced.

Abstract: An object of the present invention is to provide an ignition coil which has a structure to make it possible to connect the ignition coil to a spark plug directly and in which an installation space need not be changed largely when the ignition coil is mounted in a cylinder head, and an internal combustion engine ignition system having the ignition coil.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine. A base cover includes a plurality of receiving through holes, which are arranged at corresponding positions that correspond to positions of the plug holes, respectively. A top cover covers a top surface of the base cover and secures each ignition coil through engagement with the head of each ignition coil. Fastening bolts temporarily fasten the top cover and the base cover in a manner that allows sliding adjustment of a securing position of each ignition coil, which is loosely received in a corresponding one of the base cover through holes, in an imaginary plane that is perpendicular to an axis of each ignition coil.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine. A base cover includes a plurality of receiving through holes, which are arranged at corresponding positions that correspond to positions of the plug holes, respectively. A top cover covers a top surface of the base cover and secures each ignition coil through engagement with the head of each ignition coil. Fastening bolts temporarily fasten the top cover and the base cover in a manner that allows sliding adjustment of a securing position of each ignition coil, which is loosely received in a corresponding one of the base cover through holes, in an imaginary plane that is perpendicular to an axis of each ignition coil.

Abstract: An individual ignition type ignition coil is adopted to an engine having a plastic head cover. A secondary coil is positioned at an inner side of a primary coil, and between a secondary bobbin and a center core, a soft epoxy rein is filled The soft epoxy resin has a dent according to a compression molding and has a glass transition point Tg which satisfies a specified condition. The secondary bobbin is formed by PTS and the primary bobbin is set to the primary coil at the outer side of the secondary assembling body, and under an assembling condition the winding is carried out.

Abstract: An ignition coil has a case and a central core placed in the case. A secondary spool is wound with a secondary coil and placed outside the central core in the case. A cylindrical primary spool is wound with a primary coil and placed outside the secondary spool in the case. A resin insulator is filled in the case to maintain the insulation between each member. Air layer is partitioned in at least one of a gap between the central core and the secondary spool and a gap between the primary spool and the case.

Abstract: An integrated ignition apparatus has a coil section and a plug section. The coil section has a spring as a connection member internally. The spring electrically connects other inside terminal members of the plug section. When the coil section and the plug section are integrated, the spring is pressed, and resiliently deforms in the axial direction. Spring-back force of the spring maintains electrical connection steadily, and prevents disconnection of the spring and the terminal members due to vibration. This structure prevents failure in electric conduction between the coil section and the plug section.

Abstract: Plural ignition coils are inserted into corresponding plug holes. Each coil-head of the ignition coil is received by a holder. The coil-head is pressed by a base plate toward the engine. The holder has hooking claws. The base plate has hooking slots to movably engage with the hooking claws, so that relative position between the ignition coils and the plug holes can be adjusted. In case one ignition coil fails, the disabled ignition coil can be replaced individually. A first connector is formed on the coil-head, and a second connector is formed on the holder. The second connector is connected with the first connector when the holder is engaged with the ignition coil at one time. Thus, assembly work process can be reduced.

Abstract: In an ignition device for use in an internal combustion engine in which a spark plug and an ignition coil are integrated with each other and mounted in a cylinder head, a case is made of an electrical conductive material and one end portion of a secondary winding of the ignition coil is electrically connected to a center electrode of the spark plug while the other end portion of the secondary winding and an earth electrode of the spark plug are electrically connected to the case. Thus, the low-voltage side of the secondary winding and the earth electrode are electrically connected to each other through the case. This eliminates the need for a connector terminal and a wire harness for the electrical connection of the low-voltage side of the secondary winding to the internal combustion engine.

Abstract: In an ignition device for an internal combustion engine, comprising a spark plug made to carry out an electric discharge between an center electrode and an earth electrode and an ignition coil having a primary winding and a secondary winding for supplying a high voltage to the spark plug, notch portions are made in a ceramic spool on which one of the primary and secondary windings is wound and projecting portion are made in an insulating-resin-made holding member into which connector terminals are incorporated, with the projecting portions being engaged with the notch portions. The engagement of the projecting portions and the notch portions prevents the connector terminals from moving with respect to the ceramic spool in circumferential directions of the ceramic spool during terminal connection work.

Abstract: A product, product by process, and process according to the present invention integrates an ignition coil driver electronics or ignitor into a plughole coil housing. Electronic components are mounted directly to a printed circuit board serving as a direct connection to connector terminals and/or coil leads via plated-apertures. If required, at least one protective layer can be applied directly to an external surface of at least some of the electronic components mounted on the printed circuit board to compensate for differences in the coefficients of thermal expansion. The protective layer is selected from a group including a conformal coating, a soft buffer material, a hard epoxy globtop, and combinations thereof.

Abstract: An ignition device for an internal combustion engine has a housing, which includes a first case adjacent to the combustion chamber of the engine and a second case away from the combustion chamber. The first case has a flange formed at its end away from the combustion chamber. The second case has a flange formed at its end adjacent to the combustion chamber. The first case flange faces the side of the second case flange that is away from the combustion chamber. A bolt is screwed into the second case to engage the flanges with each other, substantially integrating the cases with each other.

Abstract: An ignition apparatus includes a high resistivity ferrite central core with a secondary winding disposed directly thereon. The ignition apparatus also includes, in a progressively coaxial fashion, a primary spool, a primary winding disposed on the spool, a case, and an outer core or shield of magnetically permeable material. The ignition apparatus exhibits reduced capacitance, and eliminates radial partial discharge at the inside diameter of the secondary winding.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine. A base cover supports the ignition coils at corresponding positions, which correspond to positions of the plug holes, respectively. A top cover covers a top surface of the base cover. Connecting bolts connects between the top cover and the base cover. Fastening bolts secures only the base cover to the engine.

Abstract: An insulator includes a coil side cylindrical portion extending from a plug side cylinder portion in a direction departing from a combustion chamber. One end of the coil side cylindrical portion protrudes in the direction departing from the combustion chamber with respect to a primary winding and a secondary winding. A pressure sensing element is disposed next to the one end of the coil side cylindrical portion. The signal lines of the pressure sensing element are taken out of a casing without passing aside an ignition coil. Thus, the diameter of the casing does not increase. The output signal of the pressure sensing element is not adversely influenced by discharge noises generated from the ignition coil.

Abstract: An ignition coil assembly of the type which is directly mounted onto an associated internal combustion engine spark plug. The coil assembly includes a spark plug boot section made of a highly elastic material with an inside cylindrical passageway. The inside passageway features ribs which engage a high voltage connection coil spring positioned in the passageway to make an electrical connection between the coil and spark plug high voltage terminals. The spring has a generally constant outside diameter outer section except its end segments have a reduced diameter where they contact the high voltage terminals. The passageway ribs retain the spring in position prior to its installation and after its removal from the associated spark plug.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine. A base cover supports the ignition coils at corresponding positions, which correspond to positions of the plug holes, respectively. A top cover covers a top surface of the base cover. Connecting bolts connects between the top cover and the base cover. Fastening bolts secures only the base cover to the engine.

Abstract: An ignition coil according to the invention is an ignition coil having a case and a coil portion accommodated in the case. The case comprises a base resin whose dielectric breakdown voltage exceeds that of polyphenylene sulfide and whose spiral flow length exceeds that of polybutyrene terphthalate. As the base resin has a high fluidity, there is only a limited risk that a defect such as a weld line is caused when molding a thin case. In addition, while the thickness of the case and the electrical insulation properties are in proportion to each other, the case comprising the base resin can ensure sufficient electrical insulation properties even if the case is formed thin.

Abstract: An ignition coil unit to be installed in a hole opened through a cylinder head of an engine having a case, an ignition coil installed in the case and comprising a primary coil connected to a power source and a secondary coil connected to a spark plug which is installed in a combustion chamber of a cylinder of the engine for producing spark discharge to ignite air-fuel mixture to generate combustion thereof in the combustion chamber, and a circuit board on which an ionic-current detection circuit, connected to the secondary coil, which detects ionic-current that flows during the combustion of the air-fuel mixture; and a processing circuit, connected to the ionic-current detection circuit, which generates an output indicative of the detected ionic-current, are formed; In the unit, an igniter is also installed in the case, thereby improving detection accuracy of ionic-current and misfiring.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine, and a base member detachably engages and holds the ignition coils at corresponding positions, which correspond to positions of the plug holes. Disengaging force for disengaging each ignition coil and the base member from each other is set to be smaller than disengaging force for disengaging each ignition coil and the corresponding one of the spark plugs from each other.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine, and a base member detachably engages and holds the ignition coils at corresponding positions, which correspond to positions of the plug holes. Disengaging force for disengaging each ignition coil and the base member from each other is set to be smaller than disengaging force for disengaging each ignition coil and the corresponding one of the spark plugs from each other.

Abstract: In an ignition device for an internal combustion engine, comprising a spark plug made to carry out an electric discharge between an center electrode and an earth electrode and an ignition coil having a primary winding and a secondary winding for supplying a high voltage to the spark plug, notch portions are made in a ceramic spool on which one of the primary and secondary windings is wound and projecting portion are made in an insulating-resin-made holding member into which connector terminals are incorporated, with the projecting portions being engaged with the notch portions. The engagement of the projecting portions and the notch portions prevents the connector terminals from moving with respect to the ceramic spool in circumferential directions of the ceramic spool during terminal connection work.

Abstract: An insulator includes a coil side cylindrical portion extending from a plug side cylinder portion in a direction departing from a combustion chamber. One end of the coil side cylindrical portion protrudes in the direction departing from the combustion chamber with respect to a primary winding and a secondary winding. A pressure sensing element is disposed next to the one end of the coil side cylindrical portion. The signal lines of the pressure sensing element are taken out of a casing without passing aside an ignition coil. Thus, the diameter of the casing does not increase. The output signal of the pressure sensing element is not adversely influenced by discharge noises generated from the ignition coil.

Abstract: In an ignition device for use in an internal combustion engine in which a spark plug and an ignition coil are integrated with each other and mounted in a cylinder head, a case is made of an electrical conductive material and one end portion of a secondary winding of the ignition coil is electrically connected to a center electrode of the spark plug while the other end portion of the secondary winding and an earth electrode of the spark plug are electrically connected to the case. Thus, the low-voltage side of the secondary winding and the earth electrode are electrically connected to each other through the case. This eliminates the need for a connector terminal and a wire harness for the electrical connection of the low-voltage side of the secondary winding to the internal combustion engine.