Capacitive pressure pickup for measuring pressure in IC engine combustion chamber

摘要

The sensor is encapsulated by a protective diaphragm (1). The combustion chamber pressure is transferred from the diaphragm as a force on a transfer plunger (2), for thermal decoupling. A lifting element is moved by the plunger, and its displacement alters the capacitance of a capacitor. The material of the measuring capacitor is chosen to match heat expansion coefficients, so that temperature changes produce insignificant capacitance changes.