Pneumatic fuse

Claim 2

A pneumatic fuse including a housing enclosing a valve chamber which has inlet and outlet passages for connecting the valve chamber in a fluid line in which maximum flow is to be controlled, a valve seat in the chamber surrounding a flow passage through the chamber, valve means located entirely in the housing and including a valve element and guide means in which the valve element is movable toward and from the seat to close and open said flow passage, the valve element being movable in the direction of fluid flow to close the flow passage, the opposite ends of the valve element being located on different sides of the flow passage, said valve means including also aligned guide bearings in the chamber in which the opposite ends of the valve element slide, the valve element having enlarged diameter portions on different sides of the seat and connected by a stem of reduced diameter, said portions on each side of the seat being exposed only to pressure in the valve chamber on that side of the seat, means for pressure balancing the enlarged diameter portions of the valve element on each side of the seat including a pressure-balancing chamber enclosed by said guide and the end of the valve element that slides in the guide, said end of the valve element being exposed to balancing pressure at the location where the valve element moves against the pressure in said balancing chamber as the valve element moves between open and closed positions, and means comprising a bleed passage connecting one of the balancing chambers with the valve chamber for delaying changes in the pressure in said balancing chamber whereby the fuse is insensitive to short pressure surges caused by momentary changes in downstream pressure, yieldable apparatus urging the valve means into open position, and adjustable means for changing the rate of flow at which the valve means close the flow passage, a portion of the adjusting means being accessible from outside of the housing.

Claim 3

The pneumatic fuse described in claim 1 characterized By the yieldable apparatus being a spring, and the valve element being in the path of the fluid flow and urged away from the seat by said spring, and the adjustable means including a movable abutment on the side of the valve element opposite the spring.

Claim 4

The pneumatic fuse described in claim 1 characterized by the adjusting means including an axially movable element of much smaller cross section than the valve element and extending through a wall of the housing.

Claim 5

The pneumatic fuse described in claim 1 characterized by the actuator being in the housing with the valve element and being exposed partly to pressure from outside the housing, bearing surfaces in the housing in which the actuator is slidable in the direction of movement of the valve element, said actuator having areas facing in opposite directions thereon and exposed to fluid pressure of the chamber and other areas facing in opposite directions and exposed to pressure from outside the housing.

Claim 6

The pneumatic fuse described in claim 3 characterized by an actuator in the housing, said housing having a cylindrical chamber at an end of the actuator remote from the valve element, a piston portion at one end of the actuator axially movable in said cylindrical chamber and means sealing the piston portion to prevent flow of fluid into the upper part of said cylindrical chamber from the chamber in which the valve element is located, the axially movable element of the adjusting means extending through an end wall of said cylindrical chamber and into contact with one end of said piston portion.

Claim 7

The pneumatic fuse described in claim 5 characterized by the actuator having a shoulder at the end of said piston portion, a passage from the valve chamber to a space in the housing on the side of the shoulder remote from the valve chamber, the area of said shoulder being equal to the area of an end of the actuator facing the valve chamber and exposed to the fluid pressure therein, whereby the actuator is substantially pressure balanced.

Claim 8

The pneumatic fuse described in claim 6 characterized by the housing having an intermediate cylindrical chamber in which a main portion of the actuator slides axially, and there are axially spaced sealing means at locations along the length of said main portion, and a vent extending from the intermediate cylindrical chamber at a location between said axially spaced sealing means.

Claim 9

A pneumatic fuse including a housing enclosing a valve chamber with a seat dividing the chamber into upstream and downstream portions, a valve element that closes against the seat in the direction of flow of the fluid to be controlled, resilient means for holding the valve element in open position, an actuator that limits the movement of the valve element by the resilient means to control its spacing from the seat when in open position, guides in the housing, the actuator having portions that slide as pistons in the guides, the upper end of the actuator having a head end piston portion exposed on its upper side to the pressure of the ambient atmosphere outside of the housing and on its lower side the valve chamber pressure, a piston portion of the actuator larger in diameter than the head end piston and having an upper area exposed to the upstream pressure of the valve chamber and a lower area exposed to the pressure of the ambient atmosphere, the pressure against said upper area being in a direction to urge the valve element toward closed position, and the pressure against said lower area of the large diameter piston portion that is exposed to pressure of the ambient atmosphere being in a direction to urge the valve element toward open position, and an adjustable device for holding the actuator in different positions of spacing from the seat to change the rate of fluid flow at which the valve element moves into closed position.

Claim 10

A pneumatic fuse including a housing enclosing a valve chamber with a seat dividing the chamber into upstream and downstream portions, a valve element that closes against the seat in the direction of flow of the fluid to be controlled, resilient means for holding the valve element in open position, an actuator that limits the movement of the valve element by the resilient means to control its spacing from the seat when in open position, guides in the housing, the actuator having portions that slide as pistons in the guides, the upper end of the actuator having a head end piston portion exposed on its upper side to the pressure of the ambient atmosphere outside of the housing and on its lower side the valve chamber pressure, a piston portion of the actuator larger in diameter than the head end piston and having an upper area exposed to the upstream pressure of the valve chamber and a lower area exposed to the pressure of the ambient atmosphere, the pressure against said upper area being in a direction to urge the valve element toward closed position, and the pressure against said lower area of the large diameter piston portion that is exposed to pressure of the ambient atmosphere being in a direction to urge the valve element toward open position, and an adjustable device for holding the actuator in different positions of spacing from the seat to change the rate of fluid flow at which the valve element moves into closed position.

Claim 11

The pneumatic fuse described in claim 8 characterized by said adjustable device being threaded through an opening in the housing at one end of the gUides in which the actuator slides, and said opening providing access of the ambient atmosphere to the head end piston portion.

Claim 12

The pneumatic fuse described in claim 9 characterized by said opening being in line with the direction of movement of the head end piston portion whereby a rod can be inserted through the opening to exert mechanical pressure on the head end piston portion.

Claim 13

The pneumatic fuse described in claim 10 characterized by fitting in said opening for connection with a conduit through which working fluid can be supplied to the upper end of the guides in place of the ambient atmosphere to move the actuator in a direction to shift the valve element into closed position.

Claim 14

A pneumatic fuse including a housing having a valve chamber therein and inlet and outlet passages for connecting the housing in series with a fluid line in which maximum flow is to be controlled, a valve seat in the chamber and surrounding a flow passage through the chamber, valve means in the chamber and movable toward and from the seat to close and open said flow passage, the valve means being movable in the direction of fluid flow to close the flow passage, the opposite ends of the valve means being located on different sides of the flow passage, aligned guides in the chamber in which the opposite ends of the valve means slide, all of the valve means, including said opposite ends, being exposed to the pressure in the chamber so that said valve means are substantially pressure balanced and said valve means being responsive to the rate of gas flow to move the valve means into closed position, yieldable apparatus holding the valve means in open position, adjustable means for changing the position of said apparatus to change the rate of flow at which the valve means closes the flow passage, a portion of the adjusting means being accessible from outside of the housing, the adjusting means including an axially movable element of much smaller cross section than the valve element and extending through a wall of the housing, the valve means including an actuator disposed between the axially movable element and the valve element, said actuator having substantially equal areas on opposite sides thereof exposed to fluid pressure of the chamber and substantially pressure balancing said actuator, the housing having a cylindrical chamber at an end of the actuator remote from the valve element, a piston portion at one end of the actuator axially movable in said cylindrical chamber and means sealing the piston portion to prevent flow of fluid into said cylindrical chamber from the chamber in which the valve element is located, the axially movable element of the adjusting means extending through said wall in alignment with said cylindrical chamber and into contact with the head end of said piston portion.

Claim 15

A pneumatic fuse including a housing having a valve chamber therein and inlet and outlet passages for connecting the housing in series with a fluid line in which maximum flow is to be controlled, a valve seat in the chamber and surrounding a flow passage through the chamber, valve means in the chamber and movable toward and from the seat to close and open said flow passage, the valve means being movable in the direction of fluid flow to close the flow passage, the opposite ends of the valve means being located on different sides of the flow passage, aligned guides in the chamber in which the opposite ends of the valve means slide, all of the valve means, including said opposite ends, being exposed to the pressure in the chamber so that said valve means are substantially pressure balanced and said valve means being responsive to the rate of gas flow to move the valve means into closed position, yieldable apparatus holding the valve means in open position, adjustable means for changing the position of said apparatus to change the rate of flow at which the valve means closes the flow passage, a portion of the adjusting means being accessible from outside of the housing, the adjusting means including an axially movable element of much smaller cross section than the valve element and extending through a wall of the housing, the valve means including an actuator disposed between the axially movable element and the valve element, said actuator having substantially equal areas on opposite sides thereof exposed to fluid pressure of the chamber and substantially pressure balancing said actuator, the housing having a cylindrical chamber at an end of the actuator remote from the valve element, a piston portion at one end of the actuator axially movable in said cylindrical chamber and means sealing the piston portion to prevent flow of fluid into said cylindrical chamber from the chamber in which the valve element is located, the axially movable element of the adjusting means extending through said wall in alignment with said cylindrical chamber and into contact with the head end of said piston portion.