Passive exhaust valve with dual torsion spring

1. A method of assembling a snap-action valve assembly, the method comprising:

fixing a valve flap to a shaft and supporting the valve flap in a conduit for rotation about a pivot axis between a closed position and an open position;

supporting a roller for rotation on the valve flap;

coupling a first end of a torsion spring to a housing and a second end of the torsion spring to the roller;

moving the housing into contact with the conduit to apply a spring preload such that the valve flap is urged into contact with an inner surface of the conduit when the valve flap is in the closed position; and

fixing the housing to the conduit to maintain the spring preload.

2. The method of assembling a snap-action valve assembly of claim 1 , further including extending a portion of the spring through an aperture extending through a wall of the conduit.

3. The method of assembling a snap-action valve assembly of claim 1 , further including sealingly fixing the housing to the conduit to restrict contaminant ingress.

4. The method of assembling a snap-action valve assembly of claim 1 , further including forming spaced apart straps on the valve flap, translating a bushing between the straps, and positioning the shaft within the bushing.

5. The method of assembling a snap-action valve assembly of claim 1 , further including positioning an end of the spring at a location to contact the valve flap as the valve flap moves from the open position toward the closed position.