Abstract: An internal combustion engine with charge stratification and spark ignition comprises a cylinder head having a main combustion chamber and a cavity defined by surrounding walls of the cylinder head and opening toward the main combustion chamber. An auxiliary combustion chamber is formed within a cup-shaped insert frictionally maintained in the cavity and opening away from the main combustion chamber. The cup-shaped insert is thin-walled and has an opening providing a passage connecting the main combustion chamber and the auxiliary combustion chamber and a pair of openings for receiving a fuel delivery device and an ignition device, respectively.

Abstract: An auxiliary combustion chamber for a stratified chage internal combustion engine is formed by an insert secured in a bore of the cylinder head. The insert is in the form of a tubular shell having openings for ignition means, fuel supply means, and having a passage communicating with the main combustion chamber. The tubular shell has a relatively massive construction in the region of the passage and is relatively thin walled in the remaining regions to provide the capability for fast warm-up of the auxiliary combustion chamber and to prevent overheating of the chamber in the region of the passage.