PreChamber

Prechamber is a term with more than one technical meaning. In architecture, it refers to a small room that precedes a larger main chamber, serving as an intermediary space. In mechanical engineering, it denotes an auxiliary combustion chamber connected to a main combustion chamber, used to improve ignition and combustion characteristics.

In architecture, a prechamber, sometimes called an antechamber or vestibule, functions as a transitional area between an exterior door and the main living or public spaces. It provides a staging area for visitors and staff, screens access, helps regulate temperature and noise, and can support storage and reception tasks. In historic homes, prechambers were commonly located near entry halls or audience rooms and could play a role in social protocol, security, and climate control within large domestic or ceremonial complexes.

In engines and related machinery, a prechamber is a small auxiliary chamber linked to the main combustion chamber by apertures or jets. It is used to initiate ignition and promote rapid, more complete combustion, with the aim of improving efficiency and reducing emissions. The prechamber contains a pilot charge or flame source; when ignited, jets issuing into the main chamber help ignite the main charge. Variants exist across spark- and compression-ignition systems, and the approach is more common in research and some heavy-duty applications than in typical modern passenger engines.

See also: antechamber, vestibule.