Flow sensor and fuel control system

摘要

A flow sensor comprising a cylinder (1) and a piston (2) movable within the cylinder (1) and dividing the cylinder (1) into first and second chambers (3, 4). The first chamber (3) communicates with an inlet (5) and the cylinder (1) has an orifice (10) which cooperates with the piston (2) to define an outlet (11) from the first chamber (4). The area of the orifice (10) varies with the position of the piston (2) within the cylinder (1). The apparatus operates to vary the pressure in the second chamber (4) so as to move the piston (2) in response to fluid flow to maintain a substantially constant pressure drop between the inlet (5) and outlet (11), each unique axial position of the piston (2) within the cylinder (1) indicating a particular flow rate. A transducer (20) senses the position of the piston (2) and thus the direction and rate of flow. <IMAGE>