| 摘要 |
<p>The invention contemplates a flow-switch construction of the straight flow-through variety wherein a magnet-bearing piston is displaced in response to a hydraulic-flow condition and in the displacement is caused to operate a magnetic-reed switch. The piston has piloted guidance in a first longitudinal portion of an elongate bore but is characterized by one or more straight channels in its periphery, whereby the piston per se constitutes lorelatively little restriction to flow; the downstream end of the piston carries a metering disc which substantially resists channel flow as long as the metering disc has predetermined close-clearance relation with the first longitudinal portion of the bore. Immediately downstream from the first longitudinal portion, the bore is substantially enlarged in a second longitudinal portion, whereby upon piston displacement such as to advance the metering disc into the second longitudinal portion, the metering disc is by-passed and unrestricted straight-through flow proceeds to the outlet end of the bore.</p> |
