Abstract This disclosure describes an improved valve, which may be used as a check valve, in which the flow of fluid in the direction to close the valve, is designed to operate the closure mechanism at a preselected rate of fluid flow. There is a housing having an inlet at one end and a valve seat at the second end. There is an axial support means which carries a valve stem with a valve head at one end, adapted to seal against the seat. The valve stem is urged away from the seat and against the flow by means of a spring, until the valve head is seated against the end of the support means. The cross sectional area of the support means is less than the cross sectional area of the valve head. The valve head is of less diameter than the internal diameter of the housing which provides an annular space through which the fluid flows, and in which there is a pressure drop. Thus, the unit pressure on the leading, upstream face is higher than the unit pressure on the lower downstream face of the valve head. The upper pressure times the exposed area on the upper surface of the head provides a downward force which is balanced by the sum of the upward forces of the fluid pressure on the lower surface of the head and the spring force. As the fluid flow increases the pressure drop increases and at a selected value of fluid flow the downward force on the valve head will be sufficient to overcome the upward forces and the valve will move downward. This movement provides a space between the lower end of the support means and the upper surface of the valve head and exposes the entire upper surface of the valve head to the upstream pressure which now provides a greater downward force on the valve head, causing it to rapidly close, shutting off all fluid flow.
A fluid flow valve adapted to close under fluid flow of a selected flow rate comprising: a valve housing having a flow passageway therein having an upstream end and a downstream end; a valve seat in said flow passageway; an axial support means within said body upstream of said valve seat; a valve head having a forward surface and a rearward surface; a valve rod extending from said valve head rearward face, the valve rod being reciprocally received by said support means, the valve head being thereby reciprocally positionable between a closed position in which the foward surfaces sealably engages said valve seat, and an opened position in which said valve head is displaced upstream of said valve seat; A shield means supported by said axial support contiguous to said valve head rearward surface when said valve head is in the opened position, the area of said shield contacting said valve head being less than the area of said valve head rearward surface whereby an unshielded area of said valve head rearward surface is impacted by fluid flow when in the closed position, such surface being substantially less than the total area of said valve head rearward surface which is impacted by fluid flow after said valve head is moved downstream away from said shield, the ratio of the valve head rearward surface unshielded area to the total area being preselected; and spring means urging said valve head upstream and into engagement with said shield, the force of said spring being sufficient to maintain the valve head in opened position against impingement thereon of fluid flow against the unshielded area until the preselected maximum flow rate is reached at which time the valve head moves away from said shield, and the force of said spring being substantially less than necessary to resist impingement of fluid flow at the preselected maximum rate against the unshielded valve head rearward surface.
Claim 2
Dependent Claim
318 words
A fluid flow valve adapted to close under fluid flow of a selected flow rate comprising: a valve housing having a flow passageway therein having an upstream end and a downstream end; a valve seat in said flow passageway; an axial support means within said body upstream of said valve seat; a valve head having a forward surface and a rearward surface; a valve rod extending from said valve head rearward face, the valve rod being reciprocally received by said support means, the valve head being thereby reciprocally positionable between a closed position in which the foward surfaces sealably engages said valve seat, and an opened position in which said valve head is displaced upstream of said valve seat; A shield means supported by said axial support contiguous to said valve head rearward surface when said valve head is in the opened position, the area of said shield contacting said valve head being less than the area of said valve head rearward surface whereby an unshielded area of said valve head rearward surface is impacted by fluid flow when in the closed position, such surface being substantially less than the total area of said valve head rearward surface which is impacted by fluid flow after said valve head is moved downstream away from said shield, the ratio of the valve head rearward surface unshielded area to the total area being preselected; and spring means urging said valve head upstream and into engagement with said shield, the force of said spring being sufficient to maintain the valve head in opened position against impingement thereon of fluid flow against the unshielded area until the preselected maximum flow rate is reached at which time the valve head moves away from said shield, and the force of said spring being substantially less than necessary to resist impingement of fluid flow at the preselected maximum rate against the unshielded valve head rearward surface.
Claim 3
Dependent Claim
57 words
A fluid flow valve according to claim 1 in which said shield has a truncated conical external configuration, the base of the conically shaped portion being smaller in diameter than the diameter of said valve head, the base of the conically shaped portion being contiguous with said valve head when the valve is in the opened position.
Claim 4
Dependent Claim
44 words
A fluid flow valve according to claim 1 wherein said shield has at least one slot in the exterior surface thereof exposing a portion of said valve head to the force of fluid flow through the valve when the valve is in opened position.