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US 4,064,755 AGranted
Liquid level sensor
AssigneeB/W Controls Inc.
InventorsEdgar A. Bongort, William T. Cruickshank
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Abstract
A liquid level sensor having a vertical guide tube with one or more magnetically operated switches therein at vertically spaced locations and a free float thereon which rises and falls with the liquid level and as it passes each switch magnetically latches it in one condition until the float returns in the opposite direction and unlatches it. The switches may be normally open, normally closed, or any combination, so that movement of the float past the switches may provide any desired circuit sequence.
Claims7
A liquid level sensor comprising, in combination:
- a guide tube for vertical positioning in the liquid whose level is to be sensed;
- a float externally surrounding the guide tube for longitudinal movement thereon to rise and fall with the liquid level and having a portion of magnetic material of low residual magnetism encircling the guide tube;
- a reed switch in the guide tube having reeds of low residual magnetism extending substantially parallel to the axis of the guide tube;
- a bias magnet in the guide tube adjacent one end of the reed switch with the magnet poles facing in opposite directions longitudinally of the guide tube;
- and
- said portion of magnetic material on the float functioning as a field conductor for the magnetic field of the bias magnet causing the switch reeds to open and remain open as the float passes by them moving in one direction, and close and remain closed as the float passes them moving in the opposite direction.
3 more elements
Dependencies are inferred from the claim text.