Air turbine starter having a force balanced, pressure energized, weighted check valve

A check valve assembly for placement between a first environment, at least a portion of which is at a first pressure (P1), and a second environment, at least a portion of which is at a second pressure (P2), wherein the difference between the first and second pressures generate a pressure force (Fp), the check valve assembly comprising:

• a valve body having an inlet port, an outlet port, and a flow passage therebetween;
• a valve seat adjacent to the valve body and having an opening therethrough, the valve seat opening in fluid communication with the valve body flow passage;
• and
• a valve element disposed between the valve seat and the valve body, the valve element capable of being acted upon by a gravitational force (Fw), a viscous force of the fluid to be communicated between the gearbox assembly and the starter housing (Fv), a buoyancy force of the valve element (Fb), and the pressure force on the valve element (Fp), the valve element further configured to translate axially to a closed position when P2<P1 and Fw<Fv+Fb+Fp.

A check valve assembly for placement between a first environment, at least a portion of which is at a first pressure (P1), and a second environment, at least a portion of which is at a second pressure (P2), wherein the difference between the first and second pressures generate a pressure force (Fp), the check valve assembly comprising:

• a backing plate having an inlet port, an outlet port, and a flow passage extending therebetween;
• a cage coupled to the backing plate, at least one portion of the cage extends across the flow passage;
• a protrusion extending from a surface of the at least one portion of the cage configured to selectively contact the valve element;
• a valve seat adjacent to the cage and having an opening therethrough, the valve seat opening in fluid communication with the valve body flow passage;
• and
• a valve element disposed between the valve seat and the valve body, the valve element capable of being acted upon by a gravitational force (Fw), a viscous force of the fluid to be communicated between the gearbox assembly and the starter housing (Fv), a buoyancy force of the valve element (Fb), and the pressure force on the valve element (Fp), the valve element further configured to translate axially to a closed position when P2<P1 and Fw<Fv+Fb+Fp.