Air flow sensor

Claim 1

An air flow sensor for measuring the rate of air flow, the sensor comprising: an air flow body having a substantially cylindrical hollow tubular cross section having at least two different internal diameters to exhaust air at a first end and receive air at the other end, said body having a shoulder formed at the junction of said diameters, an input port intermediate said other end and said shoulder and an exhaust port intermediate said shoulder and said first end and axially aligned with said input port; a cylindrical venturi insert member inserted into said first end of said air flow body and into abutment with said shoulder, said venturi insert member having a ring slot on the outer surface thereof with at least two spaced slots therein extending through the minor diameter of the venturi section for communicating with said exhaust port; a tubular impact tube extending along a diameter from the inner wall of said air flow body through said input port to the outer surface of said air flow body, said impact tube having a first and second oppositely disposed slots for receiving air flow into said first slot and exhausting air flow from said second slot, said impact tube having an axially extending passageway for diverting air flow from said first slot to a passageway along the axis of said tubular cross section; an air bypass housing mounted on said air flow body and enclosing said input and exhaust ports providing an air flow bypass chamber therebetween for receiving diverted air from said impact tube and exhausting the diverted air through said exhaust port; first and second sensors in said air bypass housing and aligned along the axis of said impact tube, said sensor elements located to receive the maximum velocity of the bypass air flowing from said impact tube; and electronic circuit means electrically connected to said sensor elements and operable to generate electrical signals proportional to the rate of air flow through said air flow sensor.