| 摘要 |
A liquid level sensor adapted to be installed inside a reservoir of a liquid to be monitored. The level sensor includes a float made from magnetic material which moves between two opposed end positions along a predetermined up-and-down path following the top surface level of the liquid. An a.c. coil driven by a pulse generator is located at one end of the float path such that the magnetic material of the float is closer to the coil at this one end of the path than at the opposite end, and is thus a variable part of the "core" of the coil which changes in response to the liquid level in the reservoir. The magnetic flux generated by the coil and/or its inductive reactance, also being a function of the variable core and thus a function of the liquid level, can be monitored electrically to provide an indication of the liquid level to an operator. The level sensor can be used to provide a signal at a predetermined level, or to provide an output which is proportional to the level of the liquid in the reservoir. It is adaptable to be used in hot and other hostile environments, and therefore has special application in the automotive industry to automatically monitor the oil level in the crankcase of an automobile. An electronic monitoring circuit is also disclosed which can be used with the level sensor to provide an indication of the liquid level to an operator. The circuit includes filter means which reduces the response of the circuit to transient indications due, for example, to movement or "sloshing" of the liquid in the reservoir.
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