| 摘要 |
A metering device that includes a housing defining a cylindrical chamber containing a reciprocating shuttle. The two opposed end parts of the chamber are interconnected by fluid flow ducts to a cylindrical valve bore. Contained with the valve is a rotary valve rod driven rotationally by a stepping motor. The valve rod has part cut away to form channels or recesses. In one rotational position of the valve rod a flow path is established from an inlet to one end of the chamber and a separate flow path is established from the other end of the chamber to an outlet. In an alternate orientation of the valve rod a flow path is formed from the inlet to the other end of the chamber and the first end of the chamber is connected to an outlet.
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