| 摘要 |
WATER TIMER A water timer including a housing having an inlet and outlet through which water flows to drive an impeller and speed reducer used to determine the open time of a valve member. The valve member is movable in one direction, corresponding with one direction of axial movement of the timer dial, into a water flow position out of engagement with a valve seat and movable in an opposite direction, corresponding with an opposite direction of axial movement of the dial, into engagement with the valve seat into a water shut-off position. The valve member has a first pressure responsive surface area facing in the opposite direction disposed in communication with water under pressure communicating with the housing inlet and a second pressure responsive surface area facing in the one direction. A controllable water pressure chamber within the timer housing communicates with the second surface area and through a first series of passages with water under pressure communicating with the first surface area when the valve member is in its water shut-off position. A biasing arrangement including the relative sizes of the first and second pressure responsive surface areas functions to bias the valve member into its water shut-off position when the dial is in its water shut-off position and a source of water under pressure is communicated with the inlet. A chamber pressure control is operable in response to the axial movement of the dial in the one direction into its water flow position to communicate the chamber with the outlet thereby changing the biasing arrangement to an extent sufficient to cause the same to bias the valve member from its water shutoff to its water flow position. |
