# US 11,898,528 B2 · Ignition device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,898,528 B2 - Document ID: US11898528B2 - Status: Granted - Kind: B2 - Application number: 18/304,871 - Filed: 2023-04-21 - Published: 2023-12-07 - Granted: 2024-02-13 - Earliest claimed: 2022-06-07 - Assignees: Diamond&Zebra Electric Mfg. Co., Ltd. - Applicants: Diamond & Zebra Electric Mfg. Co., Ltd. - Inventors: Tsutomu Kusuhara; Mitsuhiro Izumi; Hiroyuki Kimura - Web page: https://patentgrep.com/patent/US11898528B2 ## CPC - F02P 3/0435: {with semiconductor devices (F02P3/0453, F02P3/051, F02P3/0552 take precedence)} - F02P 3/051: {Opening or closing the primary coil circuit with semiconductor devices} - 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 An ignition device for an internal combustion engine that uses fuels including hydrogen. The ignition device includes an ignition coil including a primary coil and a secondary coil, a power supply device, a switching element, a spark plug, and a limiting diode. The switching element performs switching between passage and interruption of a primary current. The spark plug causes discharge at a gap, based on a high voltage induced at the secondary coil. The limiting diode includes a Zener diode that is forward-biased when oriented in a direction from the one end to the other end of the secondary coil. A breakdown voltage of the limiting diode is higher than the maximum value of an ON-state voltage obtained by multiplication of a value of a direct-current voltage applied to the primary coil by a ratio of the number of turns of the secondary coil to that of the primary coil. ## Claims ### Claim 1 An ignition device for use in an internal combustion engine that uses a fuel including at least hydrogen, comprising: an ignition coil formed by electromagnetic coupling of a primary coil and a secondary coil; a power supply device configured to apply a direct-current voltage to one end of the primary coil via a power supply line; a switching element interposed between the other end of the primary coil and a ground point, the switching element being capable of performing switching between passage and interruption of a primary current flowing through the primary coil from the power supply device; a spark plug configured to ignite the fuel by occurrence of discharge at a gap, based on a high voltage induced at one end of the secondary coil; and a limiting diode including a Zener diode or an avalanche diode that is interposed in a first connecting wire connecting directly or indirectly the other end of the secondary coil and the power supply device or the ground point, or a second connecting wire connecting the one end of the secondary coil and the spark plug, and is forward-biased when the diode is oriented in a direction from the one end of the secondary coil to the other end of the secondary coil, wherein a breakdown voltage of the limiting diode is higher than a maximum value of an ON-state voltage obtained by multiplication of a voltage value of the direct-current voltage applied to the one end of the primary coil by the power supply device, by a ratio of the number of turns of the secondary coil to the number of turns of the primary coil. ### Claim 2 (depends on 1) The ignition device according to claim 1, further comprising a control unit configured to control the switching of the switching element, wherein the control unit performs: charge control in which the switching element is placed in a closed state, and a primary current flows through the primary coil to charge the primary coil; and discharge control in which, after the charge control, a state of the switching element is changed to an open state and a high voltage is induced at the one end of the secondary coil, to cause discharge at the gap of the spark plug. ### Claim 3 (depends on 1) The ignition device according to claim 1, wherein the breakdown voltage is 1 kV or higher. ### Claim 4 (depends on 1) The ignition device according to claim 1, wherein a floating capacitor is formed between the one end of the secondary coil and the spark plug. ### Claim 5 (depends on 1) The ignition device according to claim 1, wherein the breakdown voltage is lower than an electrical breakdown voltage at the gap of the spark plug. ### Claim 6 (depends on 5) The ignition device according to claim 5, wherein the breakdown voltage is 2 kV or less. ### Claim 7 (depends on 1) The ignition device according to claim 1, wherein the limiting diode is interposed in the first connecting wire. ### Claim 8 (depends on 1) The ignition device according to claim 1, wherein the limiting diode is interposed in the second connecting wire.