Fluid operated needle valve

Claim 1

In a fluid operated needle valve comprising: a valve housing having an inlet and an outlet and an annular valve seat between said inlet and said outlet, a conical needle valve element reciprocable in said housing toward and away from sealing engagement with said valve seat to control fluid flow between said inlet and said outlet; a separate actuator housing releasably attached to said valve housing on the opposite side of said needle valve element from said valve seat, said actuator housing providing a fluid chamber, a fluid-displaceable actuator reciprocable in said fluid chamber between a retracted position away from said valve housing and an extended position toward said valve housing, fluid inlet and outlet means communicating with said fluid chamber for effecting movement of the actuator, and spring means in said actuator housing biasing said actuator to said retracted position; the improvement wherein said valve housing has a cavity therein which is open at its outer end at the side of the valve housing toward the actuator housing and is located on the opposite side of the needle valve element from said valve seat; and said actuator housing has an end wall extending across said fluid chamber therein and extending flat across the open outer end of said cavity in the valve housing, said end wall having an opening therein leading into said cavity in the valve housing and aligned with said needle valve element and said valve seat; and further comprising: a valve stem connected to said needle valve element and extending therefrom into said cavity in the valve housing and terminating thereat in an enlarged head, spring means in said cavity engaged between the inner end of said cavity in the valve housing and said head to bias the latter outwardly against said end wall of the actuator housing and to position said needle valve element away from sealing engagement with said valve seat; and a plunger attached to said fluid displaceable actuator and extending therefrom toward said end wall of the actuator housing and slidably received in said opening in said end wall in all positions of the actuator between said retracted and extended positions, said plunger in said retracted position of the actuator being retracted thereby to a position permitting said enlarged head on the valve stem to directly engage said end wall of the actuator housing around said openIng in the latter, said plunger being engageable with said head on the valve stem to move the needle valve element toward the valve seat upon displacement of the actuator from its retracted position toward its extended position.