Internal combustion engine with a secondary combustion chamber

Claim 1

An internal combustion engine comprising a head defining a primary combustion chamber, a secondary combustion chamber connected to the primary combustion chamber through a substantially straight passage at one end of the secondary chamber and extending in a direction substantially parallel thereto, and a spark plug with an electrode extending into the passage, the mixture in the secondary combustion chamber being supplied thereto only through the passage and being first ignited and burnt by a spark from the spark plug, the mixture in the primary combustion chamber being then ignited and burnt by the burnt gas which is produced in the secondary combustion chamber and is injected into the primary combustion chamber through said passage, a projection, immediately adjacent said one end of the secondary chamber, projecting into the passage and extending in a direction transverse to the passage, and structurally distinct from the spark plug, for striking the flow of the mixture pressed out of the primary combustion chamber into the secondary combustion chamber through said passage against the electrode and for shielding the electrode from direct exposure to the flow of the burnt gas injected into the primary combustion chamber from the secondary combustion chamber, said projection being substantially coextensive with the portion of the spark plug which extends into the passage in a direction transverse to said passage.