| 摘要 |
A pool sweep having a continuously-cycling, flow-interrupting valve at the upstream entrance to an inertial flow chamber. The valve has an entrance mouth with one or more closure lips pivoting been open and closed positions to open and close the mouth. The lips are biased towards closure with low creep biasing means, as by materials having a strain at its elastic limit of below 0.5 such as one or more metal springs urging the lip toward closure. The magnitude of the opening bias throughout the range of movement of the lips between open and close under dynamic flow conditions is substantially less than the closing force created by the water flow through the valve mouth urging the lips towards closure and substantially greater than the closing force imparted by flow through the mouth during lip travel from full closure to the open position. Over an initial closure-initiating region beginning from the fully open position the opening bias is substantially less than the closing force on the lips created by the water flow through the valve mouth under steady flow conditions, such as occur at start-up. Desirably, the opening bias is substantially less than the closing force on the lips created by the water flow under steady flow conditions as well over an opening-initiating region towards the open position beginning from the full closure and in the region intermediate these two end regions. |
