Adjustable snap action passive inline air valve

A bleed valve assembly comprising:

• a flow duct comprising:
• an inlet;
• and
• an outlet downstream from the inlet;
• a piston housing inside the flow duct between the inlet and the outlet so as to form an annular flow passage between the flow duct and the piston housing, wherein the piston housing is axially aligned with a center axis of the flow duct;
• a guide tube inside the piston housing, wherein the guide tube extends from an upstream end of the piston housing towards the outlet of the flow duct along a center axis of the piston housing;
• a piston inside the piston housing and configured to extend downstream of the piston housing in a closed position, and configured to slide on the guide tube;
• a fluid chamber between the piston and the upstream end of the piston housing;
• a control opening extending through the upstream end of the piston housing, wherein the control opening fluidically communicates with an interior of the guide tube;
• a hole extending through a wall of the guide tube, wherein the hole fluidically connects the fluid chamber with the interior of the guide tube;
• a control piston inside the guide tube, wherein the control piston blocks the hole from the control opening in a first position;
• a control seat inside the guide tube opposite the control piston;
• and
• a control spring between the control piston and the control seat, wherein the control spring biases the control piston toward the first position.

A valve assembly comprising:

• a flow duct comprising:
• an inlet;
• and
• an outlet downstream from the inlet;
• a piston housing inside the flow duct between the inlet and the outlet so as to form an annular flow passage between the flow duct and the piston housing, wherein the piston housing is axially aligned with a center axis of the flow duct;
• a piston inside the piston housing and configured to extend downstream of the piston housing in a closed position;
• a fluid chamber between the piston and an upstream end of the piston housing;
• a fluid passage extending through the upstream end of the piston housing, wherein the fluid passage fluidically connects the flow duct with the fluid chamber;
• and
• a control piston and a control spring inside the piston housing, wherein the control spring biases the control piston toward a first position that obstructs the fluid passage;
• and
• a control seat in contact with the control spring opposite the control piston, wherein a position of the control seat is adjustable relative the control piston.