Resettable pressure activated device
A resettable pressure activated device ( 100 ), comprises an inner wall ( 102 ), a return spring ( 105 ), a resilient element ( 110 ) and an axially movable piston ( 120 ) arranged around the inner wall ( 102 ). The piston ( 120 ) comprises a radially extending piston area ( 121 ) in fluid communication with a central bore ( 101 ) within the inner wall ( 102 ) such that the piston ( 120 ) moves in an activation direction when a bore pressure within the central bore ( 101 ) exceeds the pressure around the device by a predetermined release pressure. The return spring ( 105 ) is configured to provide a return force that is directed opposite the activation direction and has a magnitude sufficient to return the piston ( 120 ) to an idle position when the bore pressure drops below a predetermined reset level. The resilient element ( 110 ) provides a retaining force, e.g. a friction force, equal to the difference between the release force and the return force. In a preferred embodiment, the retaining force is adjustable by adjustment means ( 111 ).
1. A resettable pressure activated device, comprising:
an inner wall;
an axially movable piston arranged around the inner wall, the piston including a radially extending piston area in fluid communication with a central bore within the inner wall such that the piston moves in an activation direction when a bore pressure within the central bore exceeds the pressure around the device by a predetermined release pressure
a return spring configured to provide a return force that is directed opposite the activation direction and has a magnitude sufficient to return the piston to an idle position when the bore pressure drops below a predetermined reset level, wherein the inner wall includes an inner shoulder extending outward across the return spring from the inner wall towards the piston, and the piston includes a piston shoulder extending inward across the return spring from the piston towards the inner wall; and
a resilient element configured to provide a retaining force equal to the difference between a release force and the return force;
adjustment means for adjusting the radial force acting from the resilient element on the piston.
2. The device according to claim 1 , wherein the return spring is mounted between the inner wall shoulder and the piston shoulder.
3. The device according to claim 1 , wherein the return spring is compressed when the piston moves in the activation direction.
4. The device according to claim 1 , wherein the resilient element is a collet finger.
5. The device according to claim 4 , wherein the collet finger comprises a tapered end configured to remove debris when the piston returns to its idle position.
6. The device according to claim 1 , wherein the resilient element is connected to a retaining element configured to fit in a groove in the piston.
7. The device according to claim 1 , wherein the adjustment means is configured to adjust a radial distance between the inner wall and the resilient element.
8. The device according to claim 1 , wherein the adjustment means comprise a rotatable threaded member.
9. A resettable pressure activated device, comprising:
an inner wall;
an axially movable piston arranged around the inner wall, the piston including a radially extending piston area in fluid communication with a central bore within the inner wall such that the piston moves in an activation direction when a bore pressure within the central bore exceeds the pressure around the device by a predetermined release pressure
a return spring configured to provide a return force that is directed opposite the activation direction and has a magnitude sufficient to return the piston to an idle position when the bore pressure drops below a predetermined reset level, wherein the inner wall includes an inner shoulder extending outward across the return spring from the inner wall towards the piston, and the piston includes a piston shoulder extending inward across the return spring from the piston towards the inner wall; and
a resilient element configured to provide a retaining force equal to the difference between a release force and the return force;
a filter between the central bore and the piston area.