# US 4,393,282 A · Electrode for ignition systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,393,282 A - Document ID: US4393282A - Status: Granted - Kind: A - Application number: 06/245,170 - Filed: 1981-03-18 - Granted: 1983-07-12 - Earliest claimed: 1978-10-26 - Assignees: Robert Bosch GmbH - Inventors: Werner Grunwald; Ernst Zehender; Karl-Hermann Friese; Jurgen Schmatz; Hans Neu; Kuno Kirner; Bernd Schumacher - Web page: https://patentgrep.com/patent/US4393282A ## CPC - F02P 7/025: {with noise suppression means specially adapted for the distributor} - 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) ## Abstract The part of the distributor electrode in the breakdown region has a resistance of at least 400 ohms per millimeter. The total resistance of the electrode is in the range of between 0.5 and 1.0 kilo-ohms. The material is a mixture of a resistive ceramic material and a finely dispersed additive of metallic conductivity. Arrangements for creating surface discharge gaps thereby slowing down the sparking process and decreasing interference are also illustrated. ## Claims ### Claim 1 Electrical interference suppressed spark apparatus, paticularly distributor for an internal combustion engine, to provide a spark across a spark gap, comprising a first electrode (11); and a second electrode (16) separated from said first electrode by a spark gap, said second electrode comprising a plurality of sections (17, 18, 19) in a direction of propagation of said spark, said plurality of sections including a spark gap section (19) closest to said spark gap, said spark gap section (19) closest to the spark gap having a predetermined resistance per unit length of at least 400 ohms per millimeter in the direction of propagation of said spark. ### Claim 2 (depends on 1) Spark apparatus as set forth in claim 1, wherein the total resistance of said second electrode is at least 0.5 kiloohms. ### Claim 3 (depends on 1) Spark apparatus as set forth in claim 1, wherein the total resistance of said second electrode is between 0.5 and 1.0 kiloohms. ### Claim 4 (depends on 3) Apparatus as set forth in claim 3, wherein each of said plurality of sections of said second electrode has a different resistance per unit length, said spark gap section (19) closest to said spark gap having a highest resistance per unit length. ### Claim 5 Electrical interference suppressed spark apparatus, particularly distributor for an internal combustion engine, to provide a spark across a spark gap, comprising a first electrode (11, 21, 31, 41); and a second electrode (16, 26, 27, 37, 44, 46, 54, 56) separated from said first electrode by said spark gap, said second electrode having an end part adjacent said spark gap, and wherein at least said end part has a minimum resistance per unit length of at least 400 ohms per millimeter. ### Claim 6 (depends on 5) Spark apparatus as set forth in claim 5, wherein said second electrode is made of a material having a positive temperature coefficient above a predetermined minimum temperature. ### Claim 7 (depends on 6) Spark apparatus as set forth in claim 6, wherein said material is a silicon. ### Claim 8 (depends on 5) Spark apparatus as set forth in claim 5, wherein said second electrode is made of ceramic material comprising 10-50 mol% Cu.sub.2 O, 45-88 mol% Al.sub.2 O.sub.3, 2-5 mol% Cr.sub.2 O.sub.3 and additionally 0-1% by weight of SiO.sub.2. ### Claim 9 (depends on 8) Spark apparatus as set forth in claim 8, wherein said second electrode is made of ceramic material comprising 78 mol% Al.sub.2 O.sub.3, 19 mol% Cu.sub.2 O, 3 mol% Cr.sub.2 O.sub.3 and additionally at least 0.2% by weight SiO.sub.2. ### Claim 10 (depends on 9) Spark apparatus as set forth in claim 9, wherein the percentage by weight of SiO.sub.2 is 0.8%. ### Claim 11 (depends on 5) Spark apparatus as set forth in claim 5, further comprising means (23) arranged on said second electrode (26) for creating a surface discharge gap. ### Claim 12 (depends on 11) Spark apparatus as set forth in claim 11, wherein said means for creating a surface discharge gap comprises a plate (23) of insulating ceramic. ### Claim 13 (depends on 12) Spark apparatus as set forth in claim 12, wherein said plate is made of Al.sub.2 O.sub.3. ### Claim 14 (depends on 11) Spark apparatus as set forth in claim 11, wherein said means for creating a surface discharge gap comprises a first and second plate (23, 23) of insulating ceramic; and wherein said surface discharge gap includes a thick film between said first and second plates. ### Claim 15 (depends on 5) Spark apparatus as set forth in claim 5, wherein said second electrode comprises a plurality of high resistance sections 46, (56) and a plurality of highly conductive sections 44, (54), each of said highly conductive sections connecting two adjacent resistive sections. ### Claim 16 (depends on 15) Spark apparatus as set forth in claim 15, further comprising an auxiliary electrode (55) connected to reference potential, and an insulating layer (53) separating said second auxiliary electrode and said electrode sections. ### Claim 17 (depends on 15) Spark apparatus as set forth in claim 15, wherein said electrode is manufactured by a screen printing process. ### Claim 18 (depends on 5) Spark apparatus as set forth in claim 5 wherein said electrode is made of a mixture of resistive ceramic material and a finely dispersed additive having a high conductivity. ### Claim 19 (depends on 18) Spark apparatus as set forth in claim 18, wherein said finely dispersed additive is a metal powder. ### Claim 20 (depends on 19) Spark apparatus as set forth in claim 19, wherein said metal powder is platinum and/or palladium and/or nickel. ### Claim 21 (depends on 19) Spark apparatus as set forth in claim 19, wherein said metal powder is a mixture of palladium and silver. ### Claim 22 (depends on 19) Spark apparatus as set forth in claim 19, wherein said metal powder constitutes between 0.01 and 20% by volume of said electrode. ### Claim 23 (depends on 5) Spark apparatus as set forth in claim 5, further comprising a distributor rotor, and a center contact (14) mounted on said distributor rotor, and wherein the second electrode comprises an additional electrode part (36) abutting said distributor rotor, and a plate (33) of insulating ceramic abutting said additional electrode part; wherein said end part (37) abuts said insulating ceramic plate (33); and said additional electrode part (36), plate (37), and end part (37) are located at respective first, second and third predetermined distances from said center contact (14), said first, second and third predetermined distances increasing in that order. ### Claim 24 (depends on 5) Spark apparatus as set forth in claim 5, wherein the total resistance of said second electrode is at least 0.5 kiloohms. ### Claim 25 (depends on 5) Spark apparatus as set forth in claim 5, wherein the total resistance of said second electrode is between 0.5 and 1.0 kiloohms.