Measuring and testing – Liquid level or depth gauge – Float
Reexamination Certificate
2001-10-23
2003-07-15
Kwok, Helen (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Float
C073S30400R, C340S623000, C417S040000, C417S044100
Reexamination Certificate
active
06591676
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for detecting the level of liquid, particularly for submersed pumps.
BACKGROUND ART
The most frequent application of submersed pumps is the emptying of traps or the like to remove an excessive amount of liquids that gradually accumulates.
A typical case is the emptying of drainage traps and of water accumulated in excavations in building yards.
Submersed pumps usually have liquid level detection devices which allow to operate the pump when the level of the liquid exceeds a maximum value and to stop its operation if the level of the liquid reaches a minimum value.
Conventional liquid level detection devices are substantially constituted by appendages which protrude out of the bulk of the pump with end floats and which, by being affected by the rise or fall of the level of liquid, activate electrical connections.
Conventional detection devices are not free from drawbacks.
As mentioned, these devices in fact protrude out of the bulk of the pumps; accordingly, the trap or room from which the liquid is to be removed must be larger than the dimensions of the pump associated with the detection device.
Moreover, the correct operation of these devices also depends on the presence or absence of objects floating in the liquid.
The presence of a floating foreign object might in fact alter the detections performed by the device or even damage it.
Sometimes the detections performed by the devices can be altered also as a consequence of a turbulent motion of the liquid.
DISCLOSURE OF THE INVENTION
The aim of the present invention is to eliminate or substantially reduce the problems of conventional liquid level detection devices.
Within this aim, an important object of the invention is to provide a liquid level detection device whose detection cannot be influenced by any turbulent motions of the liquid or by the presence of foreign objects floating in the liquid.
Another object of the invention is to provide a detection device which is contained within the dimensions of the pump.
Another object of the invention is to provide a device which can detect the level of liquid with a precision which is at least equal to, or higher than, known types of device.
This aim and these and other objects which will become better apparent hereinafter are achieved by a liquid level detection device, particularly for submersed pumps, characterized in that it comprises means for detecting variation of electric and/or magnetic field in relation to the variation of the level of the liquid, said means being associated with a controller for switching on and off a submersed pump.
REFERENCES:
patent: 3553575 (1971-01-01), Shea
patent: 4053398 (1977-10-01), Venema
patent: 4091671 (1978-05-01), McLees
patent: 5856783 (1999-01-01), Gibb
patent: 6203281 (2001-03-01), Gurega
patent: 198 02 227 (1998-09-01), None
Askoll Holding S.r.l.
Josif Albert
Kwok Helen
Modiano Guido
O'Byrne Daniel
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