Patent ID: 6921029

Claim:
In an irrigation sprinkler of the type comprising a casing having a water inlet connection at the bottom for coupling the sprinkler with a pressurized source of water and a cap at the top end, and an extensible tubular riser having a water directing bore disposed within the case for movement between a retracted inoperative position within the casing and an extended operative position projecting through the cap out of the casing, the riser including a spray nozzle at its upper end and an entrance end disposed within the casing below the cap, the riser serving to direct water from the source to the nozzle for irrigating an area extending outwardly from the sprinkler, the improvement comprising: a flow stop valve assembly coupled to the entrance end of the riser within the casing including a valve head adapted to move between an open and a closed position, respectively unblocking and blocking the entrance end of the riser, and a lost motion piston and cylinder assembly coupled to said valve head for moving said valve head between said open and closed positions, said lost motion piston and cylinder assembly including a piston cyclically moveable within a cylinder between an upper and a lower position for effecting closing and opening, respectively, of said valve head; a water flow path extending between said cylinder below said piston and said bore of said riser above said valve head; a first flow control device disposed in said water flow path for limiting the rate of flow of water through said water flow path when said piston is moving downwardly within said cylinder; and a second flow control device disposed in said flow path for limiting the rate of flow of water through said water flow path when said piston is moving upwardly within said cylinder, whereby the time during which said valve head is in said closed position is controlled by said first flow control device, and the time during which said valve head is in the open position is controlled by said second flow control device.