PROBLEM TO BE SOLVED: To provide an automatic water supply device which can be put into action in such a wide range where a minimum effective water top for putting the automatic water supply device into action is roughly around 20 cmAq. to around 350 cmAq.SOLUTION: The automatic water supply device is provided with: an aqueduct 102 one opening of which is communicated with a water path 101 comprising a supply source of irrigation water a valve main body 103 mounted at another opening of the aqueduct 102 a valve body 108 moving up and down pivotally around an optional supporting point 113a, closely kept into contact with and separated from the valve seat part 104 of the valve main body 103 and a tank 112 having an air breeder 116 at an arm 111 mounted so as to face the supporting point 113a with a central focus on the valve body 108 and/or the valve body 108. A balance arm 109 engaged with the valve body 108 is extended to the valve body 108 at the opposite side of the tank 112. The gravity center of the tank 112 when filled with water is set at a position facing to a counter weight 110 with a central focus on the supporting point 113a.COPYRIGHT: (C)2008,JPO&INPIT【課題】自動給水装置を作動させる最低有効水頭が、概ね20cmAq.程度から、350cmAq.程度の有効水頭までの広範囲にわたり作動させることのできる自動給水装置を提供する。【解決手段】一方の開口が用水の供給源である水路101に連通された導水管102と、導水管102の他方の開口に設けられた弁本体103と、任意の支点113aを枢軸に上下動し、弁本体103の弁座部104に圧接離間する弁体108と、弁体108を中心にして支点113aと対向して設けられたアーム111の端部及び/又は弁体108にエアー抜き116を有するタンク112を設ける。タンク112の反対側に弁体108と連動するバランスアーム109が弁体108に延設する。タンク112の満水時の重心が、支点を113a中心としてカウンターウエイト110と対峙する位置に設ける。【選択図】図1
