# US 2019/0376441 A1 · Pre-Chamber Spark Plug > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0376441 A1 - Document ID: US20190376441A1 - Status: Published application - Kind: A1 - Application number: 16/003,272 - Filed: 2018-06-08 - Published: 2019-12-12 - Earliest claimed: 2018-06-08 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: John R. Brubaker - Web page: https://patentgrep.com/patent/US20190376441A1 ## CPC - F02B 19/12: with positive ignition (engines with non-timed positive ignition, and with incandescent chambers F02B9/08) - F02B 43/04: for improving efficiency of combustion - F02P 13/00: Sparking plugs structurally combined with other parts of internal-combustion engines ({connection of ignition coil to spark plug connector F02P3/02;} with fuel injectors F02M57/06 {; spark plug connector per se H01T13/04 – H01T13/06; predominant aspects of sparking plug, see H01T13/40 – H01T13/44}) - F02P 15/08: having multiple-spark ignition, i.e. ignition occurring simultaneously at different places in one engine cylinder or in two or more separate engine cylinders - H01T 13/20: characterised by features of the electrodes or insulation - H01T 13/32: characterised by features of the earthed electrode - H01T 13/467: {in parallel connection} - H01T 13/54: having electrodes arranged in a partly-enclosed ignition chamber - F02D 19/0647: {the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]} - Y02T 10/12: Improving ICE efficiencies - Y02T 10/30: Use of alternative fuels, e.g. biofuels - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - H01T: SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES (overvoltage protection circuits H02H) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A spark plug for an internal combustion engine includes a body that includes a terminal post, a central electrode, and a mounting sleeve that includes a threaded portion. A precombustion cavity is defined within the body. A free end of the central electrode extends into the precombustion cavity, and a plurality of posts is disposed through the mounting sleeve at the threaded portion, each of the plurality of posts protruding at least partially into the chamber by a predetermined distance (d). An electrode having one or more limbs is connected to the free end of the central electrode. A cap is disposed to close an open end of the precombustion cavity. ## Claims ### Claim 1 A spark plug for an internal combustion engine, comprising: a body that includes a terminal post adapted for connection to a source of electrical potential; a central electrode that is electrically connected to the terminal post; a mounting sleeve that includes a threaded portion, wherein the central electrode extends at least partially through the mounting sleeve; an internal insulator disposed between at least a portion of the central electrode and the mounting sleeve; a precombustion cavity defined partially within the body and between the mounting sleeve and the threaded portion, wherein a free end of the central electrode extends into the precombustion cavity; a plurality of posts disposed through the mounting sleeve at the threaded portion, each of the plurality of posts protruding at least partially into the chamber by a predetermined distance (d); an electrode having one or more limbs connected to the free end of the central electrode, each of the one or more limbs extending into the precombustion cavity and being disposed at a respective gap from a corresponding one of the plurality of posts, each respective gap having a predetermined length (D); and a cap disposed to close an open end of the precombustion cavity, the cap being connected to the threaded portion and having a cupped end forming one or more openings. ### Claim 2 (depends on 1) The spark plug of claim 1, wherein the cap includes a cylindrical wall forming a cylindrical sleeve that extends from the cupped end into the threaded portion at a location that overlaps the plurality of posts, and wherein the posts further extend through the cylindrical sleeve. ### Claim 3 (depends on 2) The spark plug of claim 2, wherein the cylindrical sleeve has an internal section that is reamed to a desired dimension at an axial location that at least overlaps the one or more limbs of the electrode. ### Claim 4 (depends on 1) The spark plug of claim 1, wherein the cap further includes a cylindrical wall that matingly engages an inner diameter of a cylindrical bore formed in the threaded portion and defines the chamber at least partially. ### Claim 5 (depends on 4) The spark plug of claim 4, wherein the cylindrical wall extends to an axial length within the chamber with respect to a centerline of the spark plug that does not overlap the electrode. ### Claim 6 (depends on 4) The spark plug of claim 4, wherein the cylindrical wall has a flat, annular end surface and an inner, concave surface. ### Claim 7 (depends on 6) The spark plug of claim 6, wherein the cap further includes a chamfer formed between the flat, annular end surface and the concave surface. ### Claim 8 (depends on 1) The spark plug of claim 1, wherein the electrode includes four limbs. ### Claim 9 (depends on 8) The spark plug of claim 8, wherein the four limbs are arranged in two pairs, each pair including two limbs that are aligned and coplanar in a radial orientation around a centerline of the spark plug, wherein first and second planes are defined by the two pairs of limbs. ### Claim 10 (depends on 9) The spark plug of claim 9, wherein the first and second planes are disposed at an angle (α) relative to one another and coincide along the centerline of the spark plug. ### Claim 11 (depends on 9) The spark plug of claim 9, wherein the plurality of posts consists of four posts, each of the four posts being aligned in the radial orientation with each of the four limbs. ### Claim 12 A spark plug for an internal combustion engine, the spark plug comprising: a body having a centerline extending along an axial direction, the body including a terminal post adapted for connection to a source of electrical potential; a central electrode that is electrically connected to the terminal post; a threaded portion connected to the terminal post via a mounting sleeve, the threaded portion forming a bore having an open end opposite the terminal post in the axial direction; a precombustion cavity defined in the body in an area opposite the terminal post, the precombustion cavity defined within and occupying the bore in the threaded portion; a cap connected to the threaded portion and closing the open end; wherein a free end of the central electrode extends into the precombustion cavity and is connected to an electrode having one or more limbs, each of the one or more limbs extending into the precombustion cavity; a plurality of posts disposed through the threaded portion and protruding into the chamber by a predetermined distance (d); wherein each of the plurality of posts is disposed at a respective gap from a corresponding one of the one or more limbs, each respective gap having a predetermined length (D). ### Claim 13 (depends on 12) The spark plug of claim 12, wherein the cap includes a cylindrical wall forming a cylindrical sleeve that extends into the bore of the threaded portion at a location that overlaps the plurality of posts, and wherein the posts further extend through the cylindrical sleeve. ### Claim 14 (depends on 13) The spark plug of claim 13, wherein the cylindrical sleeve has an internal section that is reamed to a desired dimension at an axial location that at least overlaps the one or more limbs of the electrode. ### Claim 15 (depends on 12) The spark plug of claim 12, wherein the cap further includes a cylindrical wall that matingly engages an inner diameter of the bore formed in the threaded portion and defines the chamber at least partially. ### Claim 16 (depends on 15) The spark plug of claim 15, wherein the cylindrical wall extends to an axial length within the chamber bore with respect to a centerline of the spark plug that does not overlap the electrode. ### Claim 17 (depends on 15) The spark plug of claim 15, wherein the cylindrical wall has a flat, annular end surface and an inner, concave surface. ### Claim 18 (depends on 17) The spark plug of claim 17, wherein the cap further includes a chamfer formed between the flat, annular end surface and the concave surface. ### Claim 19 (depends on 12) The spark plug of claim 12, wherein the electrode includes four limbs. ### Claim 20 (depends on 19) The spark plug of claim 19, wherein the four limbs are arranged in two pairs, each pair including two limbs that are aligned and coplanar in a radial orientation around a centerline of the spark plug, wherein first and second planes are defined by the two pairs of limbs, and wherein the two planes are disposed at an angle (α) relative to one another and coincide along the centerline of the spark plug.