| US 7,475,665 B2 | ||
| Capacitance-based fluid level sensor | ||
| Charlie Ketelhohn, Cedarburg, Wis. (US); Robert Zimprich, Milwaukee, Wis. (US); and Pat Griesemer, Franklin, Wis. (US) | ||
| Assigned to Wacker Neuson Corporation, Menomonee Falls, Wis. (US) | ||
| Filed on Jan. 15, 2007, as Appl. No. 11/623,138. | ||
| Claims priority of provisional application 60/743134, filed on Jan. 17, 2006. | ||
| Prior Publication US 2007/0163534 A1, Jul. 19, 2007 | ||
| Int. Cl. F01M 11/10 (2006.01); G01F 23/00 (2006.01); B60Q 1/00 (2006.01) | ||
| U.S. Cl. 123—196S [123/198 D; 73/304 C; 340/450.3] | 26 Claims |
| 24. A method comprising:
(A) connecting a parallel plate capacitor probe to a printed circuit board, the capacitor having a capacitance field having
a frequency which varies with fluid levels thereacross;
(B) encapsulating the printed circuit board in a potting material to form a unit;
(C) mounting the unit in a drain hole of an oil pan monitoring or to form a sensor so that a low fluid level warning signal
output is generated only if the frequency exceeds a threshold value, and wherein the frequency threshold value is exceeded
only if an oil level in the oil pan drops below a level indicative of a low oil condition.
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