Level meter for liquefied petroleum gas tank - uses magnetic coupling through cylinder wall and reed switches to vary current through vehicle fuel gauge

摘要

This device measures the level of liquified petroleum gas in a vehicle tank. A float mounted on an arm operates a gear chain to rotate a spindle through an angle of nearly 360 deg.; the angular position is directly proportional to the level of the liquid. There is a magnet (19) on the other end of the spindle, close to the tank wall. Another magnet (20) outside the tank adopts the same angle, due to the magnetic coupling through the seal (33) in the wall (30). The outside magnet drives another small magnet (31) round a ring of reed switches (32), one of which is held closed at any moment. Each reed switch can short out part of a resistor chain, which is in series with the vehicle fuel gauge. The gauge thus indicates the angular position of the magnets and hence the level of liquid.