Capacitance-based fluid level sensor

摘要

A fluid level sensor comprises a parallel plate capacitor coupled to an integrated circuit located in the bottom of an oil pan or other receptacle in which fluid level is being sensed. The sensor is preferably mounted on a drain plug for the receptacle. It includes an integrated circuit board encapsulated in a potting material disposed within the drain plug and a probe extending upwardly from the integrated circuit with its lower end also encapsulated with a resin such that its leads are protected by the resin encapsulating the integrated circuit. The probe may include one or more slotted plates in which capacitance bridges are formed within the slots or a plurality of parallel plates in which capacitance bridges are formed between adjacent plates. The sensor can be used to control operation of a gauge and/or an ignition control circuit for the machine's engine.