Liquid level sensor

摘要

A liquid level sensor is provided with a single piece pivotable device which is used to move a permanent magnet into and out of the detection zone of a magnetically sensitive component, such as a Hall effect element. The pivotable device comprises a buoyant portion, a magnet holding portion and a pivot portion with arms connecting the pivot portion to the buoyant portion and the magnet holding portion. The pivot portion of the pivotable device is shaped to be received over a fixed post attached to a container. The injection gate of the mold used to form the pivotable device is advantageously located so that the pressures throughout the mold cavity are positive to the action of the foaming agent to result in the buoyant portion of the pivotable device having a significantly lower density than the other portions of the pivotable device. This variable density in a single piece device permits a smaller overall size to be used without sacrificing the sensitivity needed to detect changes in a liquid level.