Liquid level sensor
First Claim
Patent Images
1. 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 free rotatable and longitudinal movement thereon to rise and fall with the liquid level;
a reed switch in the guide tube having its reeds extending substantially parallel to the axis of the guide tube;
means for establishing a magnetic bias field across the reeds insufficient to close them but sufficient to hold them closed;
means on the float for establishing a symmetrical toroidal magnetic field about the guide tube having leading and trailing field portions of opposite direction for sweeping the switch reeds and augmenting the bias field to close the reeds as the float passes the switch moving in one direction and sweeping and overcoming the bias field opening the switch reeds as the float passes the switch moving in the opposite direction at substantially the same point where the reeds were closed.
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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.
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Citations
36 Claims
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1. A liquid level sensor comprising, in combination:
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a guide tube for vertical positioning in the liquid whose level is to be sensed; a float externally surrounding the guide tube for free rotatable and longitudinal movement thereon to rise and fall with the liquid level; a reed switch in the guide tube having its reeds extending substantially parallel to the axis of the guide tube; means for establishing a magnetic bias field across the reeds insufficient to close them but sufficient to hold them closed; means on the float for establishing a symmetrical toroidal magnetic field about the guide tube having leading and trailing field portions of opposite direction for sweeping the switch reeds and augmenting the bias field to close the reeds as the float passes the switch moving in one direction and sweeping and overcoming the bias field opening the switch reeds as the float passes the switch moving in the opposite direction at substantially the same point where the reeds were closed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification