| 摘要 |
A metering valve used with a pressurized dispensing container, the metering valve has a valve stem assembly that slides co-axially within an annular metering chamber that surrounds the valve stem assembly and forms a substantially cylindrical chamber body. The metering valve also has an outer seal at the top of the cylindrical chamber body and an inner seal at the bottom of the cylindrical chamber body. The valve stem assembly has an outlet and an associated passage that is above the line of the outer seal when the metering valve is at rest, and is below the line of the outer seal when the metering valve is actuated, thereby creating a dispensing passage for the metering chamber's contents. The valve stem assembly has an inlet and an associated passage that is above the line of the inner seal when the metering valve is at rest, and is below the line of the inner seal when the metering valve is actuated. This arrangement controls the amount of material and fluid dispensed in each metered dose, as both passages are never open to the metering chamber at the same time. The valve stem assembly forms a straight, central passage extending from an open inner end of the valve stem assembly to a mid-point of the valve stem assembly located longitudinally within the metering chamber. The valve stem assembly has at least two elongated openings in a wall of the valve stem assembly to allow radially-directed flow between an exterior of the valve stem assembly and the central passage, the elongated openings being located to extend either side of the inner seal when the valve stem assembly is in the non-dispensing position. These elongated inlet passages serve to assure that the device is more reliable during use.
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