Patent ID: 8800364

Claim:
A device ( 1 ) for providing a signal indicating the instantaneous level of a liquid in a container, comprising a hollow body ( 2 ) wherein there is defined an inner region ( 14 , 15 ) which is divided into first and second chambers ( 14 , 15 ) which are sealingly separated from one another by a resilient diaphragm ( 6 ), the first chamber ( 14 ) having an inlet opening ( 2 c ) for pneumatic communication with the region which in the container is above said liquid, the second chamber ( 15 ) communicating with the atmosphere; a winding or coil ( 8 ) mounted in a fixed position in the body ( 2 ), on the side opposite the first chamber ( 14 ) with respect to the diaphragm ( 6 ); a core ferromagnetic ( 11 ) coupled to the diaphragm ( 6 ) and movable with respect to the winding ( 8 ) such that in the operation the inductance of the winding ( 8 ) varies as a function of the position of said core; and first resilient means ( 12 ) tending to move the core ( 11 ) towards the diaphragm ( 6 ) and second resilient means ( 16 ) tending to oppose the action of the first resilient means ( 12 ); said second resilient means ( 16 ) being disposed in said second chamber ( 15 ), wherein said second resilient means comprise a spiral spring ( 16 ) whose peripheral portion is mounted in the body ( 2 ) by a coupling which is essentially of the bayonet type, wherein the winding ( 8 ) is carried by a spool member ( 7 ) mounted in the body ( 2 ) and having an hollow lower portion ( 7 b ) in which there is mounted said spiral spring ( 16 ), and wherein the spiral spring ( 16 ) has first guiding cut-outs ( 18 ) alternated with second coupling cut-outs ( 19 ), and said hollow portion ( 7 b ) of the spool member ( 7 ) has a plurality of guiding protuberances ( 20 ) adapted to engage with said first cut-outs ( 18 ) of the spring ( 16 ) to allow the introduction of the spring in the spool member ( 7 ) up to a position in which the spring ( 16 ) is capable of being rotated such that the coupling cut-outs ( 19 ) are aligned and capable of being coupled with corresponding retaining formations ( 21 ) of said lower portion ( 7 b ) of the spool member ( 7 ).