Pressure compensating trickle rate fluid outlet

Claim 1

In a device of the character described for releasing fluid at a low rate from a pressurized source with compensation for changes in the fluid pressure at the device, the combination of: a valve cage forming a passage for fluid flow from an inlet port of the cage to an outlet port of the cage; a valve seat member forming a valve seat at the outlet port; a valve member in the cage, said valve member being biased to an idle position away from the valve seat, said valve member being smaller in cross section than the passage to permit initial fluid flow through the passage to sweep past the valve member to flush out the valve cage and the outlet port, said valve member being of a weight and cross section to be moved from its idle position to the valve seat of the valve seat member by the rising dynamic pressure of the fluid in the passage when fluid flow through the passage is initiated, whereby initiating flow of pressurized fluid through the valve cage results in flushing out the valve cage together with the outlet port and then movement of the valve member into the valve seat, and, finally, retention of the valve member in the valve seat by the pressure differential across the outlet port as long as the cage remains in communication with the pressurized source, said valve seat of the valve seat member having a minute recess to release the pressurized fluid to the outlet port when the valve member is seated in the valve seat, said valve seat member being made of resiliently deformable elastomer for progressive deformation by progressive increase in the pressure of the valve member against the valve seat in response to rise in said pressure differential, said recess being shaped, dimensioned, and located to be progressively restricted by progressive rise in said pressure differential against the valve member thereby to minimize the affect of variations in the magnitude of the pressure differential on the rate of flow through the minute recess, the outlet port of the valve cage being formed with a surrounding annular shoulder that faces downstream, the valve seat member being mounted in the outlet port, the valve seat member being of stepped configuration with a circumferential shoulder that faces upstream and seats against the annular shoulder; and retaining means abutting the downstream side of the valve seat member and pressing the valve seat member against said annular shoulder, the valve seat member thereby being under longitudinal compression in an outer circumferential zone corresponding to said annular shoulder, said recess in the valve seat member being at an inner circumferential zone spaced radially inwardly from said outer circumferential zone so that the recess is substantially unaffected by the compression of the valve seat member in said outer circumferential zone.