US 4,206,901 AGranted

Pressure-actuated valve with metering choke

AssigneeThompson Manufacturing Company

InventorTom Williams

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Abstract

A metering apparatus for controlling the rate of closure of a pressure-actuated valve of a type normally used in irrigation systems. When a pressure-actuated valve is closing, fluid from a supply line must flow into a pressure-actuating chamber, gradually filling it to force the valve's plug member against its seat. The metering apparatus is a compressible spring through which fluid must flow to enter this pressure-actuating chamber. As the valve closes, it compresses the spring through which the fluid must flow, thereby restricting the rate of flow into the pressure-actuating chamber. This reduction in flow reduces the rate at which the valve's plug member approaches its seat in an exponential manner, allowing rapid closure at first which is reduced considerably as the plug approaches its seat. Such a restricted closure rate prevents pressure shock in the supply line, otherwise known as hammering or chatter, which causes damage and excess wear and tear to the supply line, to the pressure-actuated valve and to other valves in the line.

Claims1

Dependent claims

In a pressure-actuated diaphragm valve having a body member, a seat mounted within said body member, a plug member co-operable with said seat to form a valve control chamber, inlet and outlet passageways connecting said chamber with a fluid supply line, and pilot means to cause said control chamber to fill with fluid from said supply line to force said plug member against said seat, the improvement therein comprising:

a hollow shaft, with an interior first shoulder, in said plug member which allows a fluid to flow through said plug member and into said valve control chamber;
a stem having an exterior second shoulder and having a smaller cross sectional area than said hollow shaft, said stem being mounted within said body member to protrude into said hollow shaft past said first shoulder;
and
a helical coil mounted between said first and second shoulders such that said coil is compacted when said plug member is seated against said seat and is spaced apart when said plug member is positioned away from said seat and said helical coil provides exponentially increasing resistance to the flow of fluid through its coils and into said valve-control chamber as said plug member approaches said seat.

1 more element

Dependencies are inferred from the claim text.