Liquid level sensing device
View Patent ↗A liquid level sensor includes a housing with circuitry provided therein. An inner and outer tube extend from the housing. The inner tube is positioned within a hollow center of the outer tube to form a coaxial configuration. A slot extends through the wall of the outer tube into the hollow center of the outer tube. The slot extends essentially the entire length of the outer tube. The circuitry, outer tube, and inner tube form a capacitive circuit to measure liquid. The slot allows the liquid to flow more easily into the hollow center of the outer tube and between the inner tube and outer tube to allow the sensor to provide accurate measurements with many types of fluids. The circuitry generates a pulse width modular output which is sent to a gauge to provide a visual representation of the level of the fluid in the container. By providing the pulse width modular output signal to the gauge, the sensor of the present invention can operate as a two-wire system, thereby mimicking a passive signal wire system, allowing the sensor to be a drop-in replacement for most prior art sensors.
1. A liquid level sensor comprising:
a housing having circuitry provided on a printed circuit board positioned in the housing by locating members which cooperate with openings of the printed circuit board, wherein the printed circuit board is retained in the housing by screws which make electical engagement with the circuit board,
an inner tube extending from the housing, and
an outer tube extending from the housing, the inner tube being positioned within a hollow center of the outer tube to form a coaxial configuration, a slot provided in the outer tube, the slot extending through the wall of the outer tube into the hollow center of the outer tube, the slot extending essentially the entire length of the outer tube,
the circuitry, outer tube, and inner tube form a capacitive circuit to measure liquid,
whereby the slot allows the liquid to flow more easily into the hollow center of the outer tube and between the inner tube and outer tube to allow the sensor to provide accurate measurements with many types of fluids.
2. The liquid level sensor as recited in claim 1 wherein a potting material is provided in a cavity of the housing into which the printed circuit board is inserted, the potting material provides a seal to protect the printed circuit board from environmental harm.
3. The liquid level sensor as recited in claim 1 wherein the circuitry generates a pulse width modulated output which is sent to a gauge which provides a visual representation of the level of fluid.
4. The liquid level sensor as recited in claim 3 wherein the liquid level sensor is powered through the gauge, thereby eliminating the need for a separate power supply.
5. The liquid level sensor as recited in claim 1 , wherein the screws are in electrical contact with pads on the printed circuit board and the inner tube and the outer tube are each in electrical contact with a respective one of the screws.
6. A liquid level sensor comprising:
a housing having circuitry provided therein,
an inner tube extending from the housing,
an outer tube extending from the housing, the inner tube being positioned within a hollow center of the outer tube to form a coaxial configuration,
the circuitry, outer tube, and inner tube form a capacitive circuit to measure liquid in a container.
the circuitry generates a pulse width modulated output which is sent to a gauge to provide a visual representation of the level of the fluid in the container.
7. The liquid level sensor as recited in claim 6 wherein the liquid level sensor is powered through the gauge, thereby eliminating the need for a separate power supply.
8. The liquid level sensor as recited in claim 7 wherein the circuitry is provided on a printed circuit board.
9. The liquid level sensor as recited in claim 8 wherein the printed circuit board is positioned in the housing by locating members which cooperate with openings of the printed circuit board, and the printed circuit board is retained in the housing by screws which make electrical engagement with the circuit board.
10. The liquid level sensor as recited in claim 9 wherein a potting material is provided in a cavity of the housing into which the printed circuit board is inserted, the potting material provides a seal to protect the printed circuit board from environmental harm.
11. The liquid level sensor as recited in claim 9 wherein a slot is provided in the outer tube, the slot extending through the wall of the outer tube into the hollow center of the outer tube.
12. The liquid level sensor as recited in claim 11 wherein the slot extends essentially the entire length of the outer tube.
13. A system for measuring liquid in a container, the system comprising:
a sensor having a housing with circuitry provided therein, a first tube and a second tube extend from the housing and cooperate with the liquid, the circuitry, first tube and second tube forming a capacitive circuit,
a gauge electronically connected to the sensor, the sensor providing the visual display of the level of the full for an operator to read, the gauge provides power to the sensor and the sensor sends pulse width modulated outputs to the gauge to control the visual display.
14. The liquid level sensor as recited in claim 13 wherein a slot is provided in the outer tube, the slot extending through the wall of the outer tube into the hollow center of the outer tube.
15. The liquid level sensor as recited in claim 13 wherein the slot extends essentially the entire length of the outer tube.