201213067 六、發明說明： 【發明所屬之技術領域】* 力源而動作之打螺絲機 本發明係關於將壓縮空氣作為動 等打入工具。 【先前技掏·】 巧卞碩打搫供 於打入引導部之1個螺絲之頭部，-面於螺絲扭緊方向旋 轉而進行螺絲扭緊者’其具備内裝有以壓縮空氣作為動力 源在返移動之活塞及旋轉之空氣馬達之卫具本體部。於工 具本體部之打入方向前端設有上述打入引導部。空氣馬達 與活塞-體往返移動，其輸出轴上安裝有起子頭。起子頭 之前端部到達打入引導部内。打入引導部中，併設有盥工 具本體部之打人動作連動作動之螺絲供給部與收納有多、數 螺絲之箱殼。 於工具本體部之側部設有使用者把持之把手部，該把手 部之基部附近設有使用者以指尖操作之觸發形式之開關 桿。若拉伸操作開關桿則對工具本體部之活塞上室供給麼 縮空氣’活塞下動’又空氣馬達旋轉，完成螺絲打入。若 解除開關桿之拉伸操作則供給於活塞上室侧之壓縮空氣流 入於活塞下室側，活塞及空氣馬達一體返回至上死點。流 入於活塞下室側之屡縮空氣（返回空氣）之一部分流入於螺 絲供給部，作為螺絲發送之動力源而利用，此外主要經由 排氣通路與大氣相通。 如此之打螺絲機中，提供具備將用以對木材打入螺絲之 156792.doc 201213067 打木模式與用以對鋼板打入螺絲之打鋼板模式進行切換之 功能者。於前述之打木模式，為降低打入時之反作用力， 或避免螺牙之打入（導致不僅以空氣馬達使螺絲旋轉緊固 亦以釘之方式打入）而輸出比較低之打入力，另一方面， 於後者之打鋼板模式’輸出大於打木模式之打入力。先 冑’作為用以切換打人力之方法，除眾所周知切換向活塞 上室供給之壓縮空氣之壓力之技術外，下述專利文獻中揭 不有藉由切換活塞下室之排氣效率而進行輸出模式之切換 之技術。 下述專利文獻所揭*之輸錢式切換技術係利用使通過 於活塞下室之排氣通路之口徑變化時排氣效率產生變化， 活塞之下動速度亦產生變化之原理者，於工具本體部上設 置具有大小2個排出口之旋轉板，切換該旋轉板之位置， 將排氣通路之排出口之口徑切換成大徑孔（打鋼板模式） 時，活塞下室之排氣效率提高，結果變成活塞之下動速度 高速化，相對於螺絲之打擊力大於打木模式之構成。將旋 轉板之位置切換於小徑孔側（打木模式）時，排出口之口徑 變成小口徑，活塞下室之排氣效率下降，其結果變成活塞 之下動速度變慢，打擊力變小之構成。 又，下述專利文獻所揭示之打入工具中，作為打入結束 後用以使活塞從下死點返回至上死點之回收空氣，係採用 利用供給於活塞上室之打擊力之產生用壓縮空氣之排氣回 收方式。於該排氣回收方式，成為打入結束後不僅保持排 氣活塞上室之壓縮空氣，且若將暫時流入於活塞下室之其 156792.doc 201213067 -部分作為活塞回位用壓縮空氣而利用，則剩餘之壓縮空 氣經過排氣通路而排氣之構成。 [先前技術文獻] [專利文獻] [專利文獻1]曰本特開2006-983號公孝民 【發明内容】 [發明所欲解決之問題] 藉由如此採用#氣回收方<，且將排氣通路之口徑進行 大小切換，而進行輸出模式之切換之構成之打入工具中， 更提南先前打鋼板模式之輸出有限度。 採用上述排氣回收方式之情形中，為謀求高輸出化而使 排氣通路大口徑化而提高排氣效率時，會導致打入结束後 從活塞上室流入於活塞下室之較多壓縮空氣經過㈣通路 排氣m ’打入結束後用以使活塞返回至上死點之回 收空氣不足，有產生活塞無法返回至上死點之動作不良之 虞。因此’先前採用排氣回收方式之構成中，要藉由排氣 通路之大口徑化而謀求高輸出化有其限度。 " 、 因此，本發明之目的係例如在採用排氣回收方式之打入 工具/中’充分確保活塞下室内之回收空氣，且使職祕 大口徑化而提高排氣效率，藉此可使打入工具更高輸出 化0 [解決問題之技術手段] 上述問題由以下發明得以解決。 第1發明係一種打入工具，其係經由排氣通路將活塞下 156792.doc 201213067 室排氣’且以供給於活塞上室之壓縮空氣使活塞下動而產 生打入力者，且具備於活塞之下動時開放排氣通路、於活 塞之上動時擠壓排氣通路之排氣柯。 根據第1發明，使排氣通路大口徑化，提高活塞下室之 排氣效率，藉此可使打入力高輸出化。排氣通路利用排氣 閥之作動使其有效通氣面積產生變化。排氣通路在活塞上 動時排氣閥作動於擠壓側且小口徑化，另一方面在活夷 下動時排氣閥作動於打開側且大口徑化。 因此，即使謀求使排氣通路大口徑化，打入力之高輸出 化，打入結束後排氣閥亦作動，由此擠壓排氣通路，因此 可適當抑制活塞下室之排氣效率，藉此可使回收空氣充分 流入於下室内，可確實使活塞返回至上死點。 第2發明係如第i發明之打入工具’其具備利用手動操作 使排氣通路之排氣口之口徑變化、而使前述打入力變化之 輸出模式切換機構。 根據第2發明，例如藉由手動操作輸出模式切換刻产 盤，使排氣口之大小變化，而可切換打入力較小之打木: ^與打入力較大之打鋼板模式。除利用該輸出模式切換機 構之模式切換外，1次打入動 _ 中’排氣通路藉由排氣關 而以適當之時序擠壓，藉此在 徘礼閥 ^以塞下㈣可獲得較大打入 力，另一方面，活塞上動時可確 作保活塞下至内充分量之回 二軋，避免該打入工具之動作不良。 第3發明係如第丨或第2發明 收姓槿_ τ入工具’其具備排氣回 叹、，，。構，该排氣回收結構係 、使供給於活塞上室之壓縮空 156792.doc 201213067 里由回收空氣通路流入於活塞下室，將其一部分作為用以 使活塞返回至上死點之回收空氣加以利用，其餘經由排氣 通路予以排氣者。 根據第3發明’所謂具備排氣回收結構之打入工具中， 藉由利用排氣閥在活塞上動時擠壓排氣通路，而可確保活 塞下室充分之回收空氣，避免該打入工具之動作不良，因 此對進而使排氣通路大口徑化謀求該打入工具之高輸出 化’可消除先前之限度。 第4發明係如第3發明之打入工具，其係利用回收空氣通 路内之回收空氣使排氣閥於擠壓方向作動而構成。 根據第4發明，具備排氣回收結構之打入工具中，打入 結束後利用經由回收空氣通路從活塞上室流入於活塞下室 之回收空軋，使排氣閥作動於擠壓側，藉此以適當之時序 元成活塞下室之排氣效率之抑制。 第5發明係如第1〜第3之任一發明之打入工具，其具備將 活塞上室對蓄壓室開閉之頂閥，且利用關閉該頂閥之壓縮 空氣使排氣閥作動於擠壓方向而構成。 根據第5發明，取代利用上述排氣回收結構中之回收空 軋通路内之回收空氣而使排氣閥動作於擠壓側之構成，在 打入結束後利用使頂閥作動於關閉侧之壓縮空氣，使排氣 閥作動於擠壓側，藉此可適當抑制活塞下室之排氣效率， 利用充分量之回收空氣確貫使活塞返回至上死點。該構成 對於不具備排氣回收結構之打入工具亦可適用。 第6發明係第3或第4發明之打入工具，其中使排氣通路 I56792.doc 201213067 與回收空氣通路合流。根據第6發明，與使排氣通路與回 收空氣通路相互獨立而設之構成相比，可謀求通路構成之 簡化’又易使排氣通路更大口徑化。 第7發明係如第1〜第6之任一發明之所謂打螺絲機，其中 内裝有以壓縮空氣作動之空氣馬達，一面利用活塞之下動 打擊螺絲並使該空氣馬達旋轉而緊固螺絲。對於所謂打螺 絲機可應用第1〜第6之任一發明之構成。因此第丨〜第石之 任一發明之構成亦適用於不内裝如此空氣馬達之打入工具 的例如壓縮空氣式打釘機。 【實施方式】 接者’基於圖1〜圖1丨說明本發明之實施形態。圖丨係顯 示第1實施形態之打入工具i之全體之内部結構。例示之打 八1即所δ胃打螺絲機，係具備緊固於一面打擊丨個螺絲 Β —面於螺絲扭緊方向旋轉之打入材w之功能之空氣工 具。 打入工具1具備工具本體部2與把手部3與打入引導部4 與打入工具供給裝置5。工具本體部2具備大致圓筒體形狀 之本體殼2a上’内裝有以下說明之打擊機構部_空氣馬 達30等各機構之構成。從工具本體部2之側部向側方突出 之狀態設置使用者用以把持之把手部3。該把手部3之前端 側:圖不省略。通過經由連結器連接於該把手部3之前端 之空，管於該把手部3之内部儲存壓縮空氣。以下’將該 把手°P 3之内部，儲存作為動力源之壓縮空氣之區劃稱作 =B 儲存槽3a與於本體殼2a内側之打擊機構部10及 156792.doc 201213067 空氣馬達30周圍所區劃之蓄壓室2b時常連通。 該把手部3之基部附近，設有以使用者把持之手之指尖 進行拉伸操作之觸發形式之開關桿6，與利用該操作而作 動之觸發閥4 0。藉由伴隨開關桿6之操作之觸發閥4 〇之開 關’壓縮空氣在工具本體部2側給排氣。 打入引導σρ 4係具有將供給於打入通路4a内之1個螺絲b 以起子頭7打擊而引導至打入材w之功能者，設置成從工 具本體部2之下部向下方（打入材貿側）突出之狀態。打入引 導部4之前端設有接觸臂8。僅在該接觸臂8按壓於螺絲打 入部位之狀態下開關桿6之拉伸操作才有效，完成以工具 本體部2之打入動作，藉此防止不注意之打入動作。對於 該失誤操作防止機構係先前眾所周知，因此省略詳細說 明。 又，本實施形態在工具本體部2中之排氣結構上具有特 徵，對於打擊機構部1〇、空氣馬達3〇及觸發閥4〇等之基本 構成，係先前眾所周知，於本實施形態中無需特別改變。 再者’對於打入引導部4及打入工具供給裝置5，亦為先前 眾所周知，因此省略詳細說明。 以下’沿著供給於儲存槽3a之壓縮空氣之流動，自上游 側對各部分之構成進行說明。首先，觸發閥40收納於設於 把手部3之基部之閥殼部3b内。該觸發閥40具備閥外框部 41與閥内框部42與閥門桿43。閥殼部3b内側無法移動地安 裝有閥外框部41。閥外框部41之内側可上下移動地收納有 閥内框部42。閥内框部42之内側可上下移動地收納有閥門 156792.doc 201213067 桿43。閥門桿43之前端側從閥外框部41 1田同下方突 出’與開關桿6之背面碰撞。儲存槽3&之空氣壓時常作 於閥門桿43之上面。 用 不拉伸操作開關桿6之非作動狀態下，觸發閥4〇關閉。 於觸發閥40之關閉狀態，成為工具本體部2側之作動空氣 通路2c通過閥殼部3b之閥殼孔3c與閥外框部41之第！空氣 孔41a、閥外框部41與閥内框部42之間、閥外框部41之第2 空氣孔41b，與儲存槽3a連通之狀態，成為經由作動空氣 通路2c對頂閥上室1丨&供給壓縮空氣之狀態。 頂閥11具有使活塞上室12a對蓄壓室2b開閉之功能，利 用壓縮彈簧13而賦能於關閉側。因此，經由作動空氣通路 2c對頂閥上室lla供給壓縮空氣之狀態下，在與作用於打 開側之蓄壓室2b之壓縮空氣間，空氣壓相互抵消，結果頂 閥11藉由壓縮彈簧13而保持於關閉位置。頂閥丨丨保持於關 閉狀態，結果不對活塞上室12a供給壓縮空氣，從而工具 本體部2保持在非作動狀態》 如圖2所示，開關桿6向上方拉伸操作時，閥門桿43與壓 縮彈簧43a及儲存槽3a之空氣壓對抗而上動。若閥門桿43 上動’則儲存槽3a之空氣壓作用於閥内框部42之上面，因 此閥内框部42下動。若閥内框部42下動，則作動空氣通路 2c從儲存槽3a截斷，另一方面，經由閥外框部4丨之大氣開 放孔41c與大氣相通。若作動空氣通路2c與大氣相通，則 頂閥上室11 a與大氣相通，因此頂閥丨丨利用蓄壓室2b之空 氣壓與壓縮彈簧1 3對抗而向上方打開。若頂閥丨丨打開，則 156792.doc •12- 201213067 蓄壓室2b之壓縮空氣流入於活塞上室12a，此作用於活塞 12之内周側上面，壓縮空氣對該活塞12作用於下動方向。 另，圖3中，壓縮空氣之流動（給排氣）係以空白箭頭表示。 活塞12利用流入於活塞上室12a内之壓縮空氣而開始下 動。若活塞12開始下動，則空氣馬達3〇與其一體開始下 動。空氣馬達30之下部側（後述之底板34勾氣密地收納於安 裝於本體殼2a之氣紅18内。氣缸18之下部安裝有前緩衝塾 19。該前緩衝墊19之内周側插通有起子頭7。氣缸18之内 周側的空氣馬達30之下方相當於活塞下室25。 活塞下室25經由前緩衝墊19之内周側及排氣通路％與大 氣側連通。排氣通路26到達本體殼2a之上部。本實施形態 中，該排氣通路26形成為比先前更大口徑，其有效通氣面 積充:大地形成，藉此活塞下動時（打入螺絲時）之排氣效 率提高’可獲得先前所沒有之大打擊力。 於本體殼2a之上部，作為輸出模式切換機構之—例，安 裝有圓板形之輸出模式切換刻度盤45。該輸出模式切換刻 度盤45上，設有大口徑之大排氣口 45a與小口徑之小排氣 (圖中未』不）。稭由使用者手動旋轉該輸出模式切換刻 度盤❿可任意切換為使大排氣口仏位在排氣通路％上 端之狀癌（打鋼板模式），哎使+ # $ $ / a 端之狀態(打木模式)。此===排氣通路26上 之鋼球之止動裝置价予以保持。 八備鉍弹簧賦能 打:=，該輸出模式切換刻度盤45切換為前者之 ，排風通路26之有效通氣面積可维持原狀， i56792.doc • J3· 201213067 且可維持向排出效率。因此於該打鋼板模式下，在打鋼板 作業等中，可輸出大打擊力。相反，若將輸出模式切換刻 度盤45切換成後者之打木模式，則排氣通路％在其流出口 爻擠壓，因此其有效通氣面積縮小，排氣效率下降❶因此 於5亥打木模式下，可抑制打擊力變小、螺絲打入時之反作 用力’該點可提高該打入工具1之操作性。 如圖所示，排氣通路26中介裝有排氣閥2〇。該排氣閥2〇 八有藉由返回時縮小排氣通路26之有效通氣面積而降低其 排氣效率之功能，此成為本實施形態之一大特徵。後述關 於該排氣閥20之詳情。 空氣馬達30之衝程軸部31可上下相對移動地插通於活塞 12之内周側。於該衝程軸部31之上端部設有止動凸緣部 32 °該止動凸緣部32之下側設有4個馬達空氣流入口 33〜33。頂閥11打開而流入於活塞上室丨2a内之壓縮空氣， 亦經由§亥馬達空氣流入口 33〜33而流入於衝程轴部3 1之内 周側。 利用經由馬達空氣流入口 3 3 ~3 3流入於衝程軸部3 1之内 周側之壓縮空氣，使空氣馬達30開始旋轉。空氣馬達3〇具 備對其衝程軸部3 1偏心之馬達殼部34，於該馬達殼部34之 内周側具備可使輸出基座36與複數塊鰭片35〜35向放射方 向變位收納之眾所周知之構成。輸出基座36經由軸承 36a、36b對馬達殼部34可旋轉地收納❶經由衝程軸部31之 内周側於該馬達殼部3 4内流入壓縮空氣時，藉由使其接受 各鰭片35而使輸出基座36旋轉，藉此各鰭片35向放射方向 156792.doc •14- 201213067 往返移動而進行給排氣。如圖3所示，馬達空氣之排氣係 經由設於本體殼2a之側部之排氣口 2(1而進行。 於空氣馬達30之輸出基座36之下端部形成有輸出齒輪 36c。該輸出齒輪36c與減速用行星齒輪排37連結。該行星 齒輪排37之齒輪座37aJl安裝有起子頭7。齒輪座37&經由 軸承38而對馬達殼部34之底板34&可旋轉地支持。 利用流入於活塞上室12a之壓縮空氣，活塞12及空氣馬 達0 ϋ下動，且e亥空氣馬達3〇旋轉，藉此起子頭7使打 入通路4a内螺絲於緊固方向旋轉且下動，藉此供給於打入 通路4a内之1個螺絲B以起子頭7予以打擊，其後於緊固方 向旋轉而緊固於打入材^中。 如圖3所不，活塞12與空氣馬達3〇一體下動，活塞a到 達其下端位置後’空氣馬達3〇單獨進而下動。設於活塞Η 之上部周圍之活塞止動部12b與本體殼2a之中間基座部k 之上面抵接，藉此限制活塞12之下動端位置。 如圖3中之空白箭頭所示，活塞12到達下動端時，設於 其周圍之複數之辅助通氣孔12c〜12c與設於中間基座部“ 周圍之複數之辅助通氣孔2f〜2f 一致，因此向頂閥u及活塞 12,内周側之壓縮空氣之供給量立即增加，藉此空氣馬達 3 0單獨下動且以高扭矩開始旋轉。 如圖4所不，活塞12之下動停止後，藉由空氣馬達3〇單 獨下動而11又於其衝程軸部31上端之止動凸緣部3 2與活塞 之内周側上面抵接，該空氣馬達3 〇亦到達其下動端位 置。藉由止動凸緣32與活塞12之内周側上面抵接，而停止 156792.doc •15· 201213067 從活塞上室12a向空氣馬達3〇之壓縮空氣之供給，停止該 空氣馬達30之旋轉。於該時間點，螺絲8之相對於緊固材 W之緊固結束。 藉由如上拉伸操作開關桿6，使觸發閥4〇打開，而對活 塞上室12a供給壓縮空氣，使活塞12下動，且使空氣馬達 30—面旋轉一面與活塞12一體下動，其後進而一面以高扭 矩旋轉一面單獨下動，到達下動端位置，藉此將供給於打 入通路内4a之1個螺絲B打擊緊固至打入材w。 如圖5所示，螺絲打入結束後，若使用者解除開關桿6之 拉伸操作，則觸發閥40之閥門桿43利用壓縮彈簣43&之賦 能力及儲存槽3a内之空氣壓返回至下方之關閉位置。藉由 閥門桿43返回至關閉位置，而按壓開關桿6並返回至關閉 位置。 若閥門桿43返回至關閉位置，則儲存槽3a對閥内框部42 之上面阻斷，因此相對於該上面之儲存槽3a之空氣壓不作 用，其結果，閥内框部42利用壓縮彈簀43a之賦能力而上 動。若閥内框部42上動，則該閥内框部42與閥外框部41之 間與大氣側（大氣開放孔41c)阻斷，另一方面，作動空氣通 路2c經由閥殼部3b之閥殼孔3c、閥外框部41之第1空氣孔 41a、閥外框部41與閥内框部42之間、閥外框部41之第2空 氣孔41b而與儲存槽3a連通。 如此作動空氣通路2c與儲存槽33連通時，壓縮空氣經由 作動空氣通路2c流入於頂閥上室1丨a，頂閥丨丨利用壓縮彈 簧丨3下動，藉此活塞上室i2a與蓄壓室2b側阻斷，停止向 156792.doc 201213067 該活塞上室12a之壓縮空氣之供給。 若關閉頂閥11，則關入於活塞上室12 a内之壓縮空氣作 為用以使活塞12及空氣馬達30返回至上死點之回收空氣加 以利用。因此本實施形態之打入工具1成為排氣回收類型 之打入工具。 於本體殼2a之上部設有圓筒形狀之上部基座部2g »利用 該上部基座部2g區劃頂閥上室1 la。設於頂閥11上部之衝 程轴部11 b可上下衝程且氣密地保持於該上部基座部2g之 内周側。於該衝程軸部11 b之上方的上部基座部2g之上 部，安裝有閥止動件14。於閥止動件14之下側的上部基座 部2g之側部設有複數之排氣孔15〜15。於該所有排氣孔 15〜15之外周側安裝有環狀之止回閥16。又，回收空氣通 路17與上部基座部2g周圍連通。止回閥μ允許從上部基座 部2g之内周側經由排氣孔丨5〜1 5向回收空氣通路丨7之壓縮 空氣之流動’阻斷其相反方向之壓縮空氣之流動。 如圖2〜圖4所示’頂閥11上動’而活塞上室123相對於蓄 麗至2b為打開之狀態下，成為頂閥丨丨之衝程軸部1丨b與閥 止動件14碰撞，活塞上室12a對排氣孔15〜15為氣密阻斷之 狀態。與此相對，如圖丨及圖5所示，頂閥u下動，活塞上 室12a與蓄壓室孔阻斷之狀態下，成為頂閥u之衝程軸部 11b與閥止動件14分離，活塞上室12a與排氣孔15~15側連 通之狀態。因此，如圆5所示，頂閥u下動，關入於活塞 上至12a之塵縮空氣經由排氣孔1 $〜15及止回閥16流入於回 收空氣通路17内。 156792.doc 201213067 回收空氣通路17經由設於氣缸18之下部的前緩衝墊19之 外周側之回收孔1 8a與活塞下室25連通。因此，經由排氣 孔15~15及止回閥16從活塞上室12a流入於回收空氣通路17 内之壓縮空氣經由該回收空氣通路17及回收孔18a流入於 活塞下室25内。經由回收空氣通路17從活塞上室12a流入 於活塞下室25之壓縮空氣（回收空氣）作用於空氣馬達3〇之 底板34a，藉此最終活塞12及空氣馬達30從下死點返回至 上死點。 如圖6所示’空氣馬達39開始上動後，回收空氣之一部 分立即經由前緩衝墊19之内周側流入於排氣通路26内並排 氣。 此處，如前述’排氣通路26上設有排氣閥20。該排氣閥 20之詳情如圖7及圖8所示。根據第1實施形態，該排氣閥 20設於回收空氣通路π與排氣通路26之間《第1實施形態 之排氣閥20具備排氣活塞21與壓縮彈簧22 ^排氣活塞21在 圖中於左右方向可移動地支持於如圖5、圖6及圖8所示突 出擠壓於排氣通路26内之位置，與如圖丨〜圖4及圖7所示從 排氣通路26内退出之開放位置之間。若排氣活塞2丨移動至 前者之擠壓位置，則排氣通路26之有效通氣面積變小，因 而排氣效率下降。排氣活塞21移動至後者之開放位置時， 排氣通路26之有效通氣面積變大因而排氣效率提高。 該排氣活塞21利用壓縮彈簧22而賦能於開放排氣通路％ 之開放位置側。回收空氣通路17之空氣壓經由作動孔23作 用於排氣活塞21之上面（圖中左側面）。如圖7所示，壓縮空 156792.doc -18- 201213067 氣未流入於回μ氣通路17内之狀態下，排氣㈣利用塵 縮彈簧22保持在開放位置，因此維持排氣通路％之高排氣 效率。與此相對，如圖8所示1閉頂閥U，關入於活塞 上室12a之壓縮空氣經由排氣孔15七及止回閥⑽入於回 收空氣通路17内時，其空氣壓經由作動孔”作用於排氣活 塞21 ’藉此排氣活塞21與壓縮彈簧22對抗，移動至擠壓位 置因此，若從活塞上室12a經由回收空氣通路17對活塞 下室25供給回收空氣，則㈣與此同時排氣閥2叫動於擠 壓側，排氣通路26受擠壓，抑制排氣效率之狀態。 如此，使排氣通路26形成比先前大口徑，提高其排氣效 率，藉此可輸出先前所無法獲得之大打擊力，另一方面， 打擊、’、σ束後變成利用排氣閥2G抑制排氣通路26之排氣效率 之狀態’因此流入於活塞下室25之回收空氣之大部分為使 活塞12及^氣馬達3〇返回至上死點而消耗，因此活塞12及 空氣馬達30確實返回至上死點。 如圖5所示，若回收空氣流入於活塞下室乃，則其作用 於空氣馬達30之底板34^藉由底板34a與衝程軸部 31之上 面之面積差，首先空氣馬達3〇利用回收空氣室25側之空氣 壓而上動。如圖6所示，若空氣馬達3〇對活塞12上動，則 止動凸緣部32與活塞12之内周側上面分離，因此活塞上室 12a經由馬達空氣流入口 33〜33與衝程軸部31之内周側連 通，藉此活塞上室12a經由馬達空氣供給路及排氣口 2(1與 大氣相通。另一方面，經由回收空氣通路17流入於活塞下 至25之回收空氣利用止回閥μ防止向活塞上室12a之逆 156792.doc -19- 201213067 流。如此活塞上室12a與大氣相通，另一方面回收空氣流 入於活塞下室25，藉此空氣馬達30進而上動。 又，從活塞上室12a經由馬達空氣流入口 33〜33流入於馬 達空氣供給路之壓縮空氣（馬達排氣）之一部分作用於活塞 12之下面，因此於該時間點活塞12亦開始上動。 經過圖6所示之狀態，設於空氣馬達3〇之衝程軸部“周 圍之止動墊圈39與中間基座部2e之下面抵接，該空氣馬達 30到達上死點。如此，空氣馬達3〇返回至上死點，同時活 塞12利用馬達排氣而上動，最終空氣馬達3〇之止動墊圈 與下面抵接之狀態下，以上動之空氣馬達3〇按M，藉此返 回至上死點。 流入於活塞下室2 5之回收空氣經由排氣通路2 6從輸出模 式切換刻度盤45之大排氣口 45a向大氣排出，此外經過前 緩衝墊丨9之内周側亦從打入通路钧内向大氣排出。活塞下 室25内之回收空氣向大氣排出，結果回收空氣通路17内之 空氣壓下降時，排氣活塞21利用壓縮彈簧22返回至開放位 置，該排氣閥2 0返回至初始位置。 又，打入工具供給裝置5之空氣通路“與回收空氣通路 17連通。因此，如圖5所示打入結束後，從活塞上室流 入於回收空氣通路17之壓縮空氣之一部分經由空氣通路h 供給於打入工具供給裝置5。利用經由空氣通路&供給之 壓縮空氣發送之活塞5b與壓縮彈簧5c對抗而後退。若使活 塞下室25内之回收空氣排氣，則發送活塞5b藉由壓縮彈菁 5c前進。發送活塞5b上設有發送爪5d、若發送活塞％ 156792.doc •20· 201213067 前進，則1個螺絲B利用發送爪5d、5d供給於打入通路4a 内。 利用如上構成之第1實施形態之打入工具1，排氣通路26 形成比先前大口徑’提高活塞下室25之排氣效率，因此可 對板厚更厚之鋼板以高輸出打入螺絲B。 並且’排氟通路26上介裝有排氣閥20。該排氣閥2〇具有 使排氣通路26之有效通氣面積變化之功能。利用該排氣閥 20，在活塞下動時螺絲打擊時（緊固時）向開放位置移動， 使排軋通路26之有效通氣面積擴大，藉此提高活塞下室25 之排氣效率，完成更高輸出之打擊，另一方面，打擊結束 後活塞上動時向擠壓位置移動，縮小排氣通路26之有效通 氣面積，藉此抑制活塞下室25之排氣效率，藉此，可充分 確保用以使活塞12及空氣馬達3 〇返回至上死點之回收空 氣’防止該打入工具1之動作不良。 如此，先前為避免打擊結束後之回收空氣不足，而使排 氣通路大口徑化而提高活塞下室之排氣效率雖有限度，但 根據本實施形態之打入工具i，彳充分確保目收空氣，且 可謀求使排氣通路26更大口徑化之先前較_之打入力之 高輸出化，因此可消除如此先前之限度。 ’藉由與上述排氣閥 45 ’而可固定地切換 又’根據本實施形態之打入工具1 2〇分開旋轉操作輸出模式切換刻度盤 氣通路之有效通氣_只，柯μ任意、選擇高輸出之打鋼 板模式與低輸出之打木模式。任何情形中排氣閥都以一 定時序（打擊結束後活塞上動時）作動，因而可充分綠保回 156792.doc -21- 201213067 收空氣，使活塞12及空氣馬達3〇確實返回至上死點，因此 將不會產生動作不良。 可對以上說明之第1實施形態加入各種變更而實施。例 如，雖例示利用排氣回收結構中回收空氣通路17内之回收 工氣，使排氣閥20作動於擠壓側之構成，但亦可取代此， 在打入結束後利用在關閉頂閥丨丨側作動之壓縮空氣，而使 排氣閥50作動於擠壓側之構成。該第2實施形態之打入工 具顯示於圖9及圖10。第2實施形態之打入工具關於排氣閥 50之構成與第！實施形態不同，關於其他構成與第】實施形 態相同，因此使用相同符號省略其說明。 第2實施形態之情形中’如圖9及圖1〇所示，設有作動空 氣通路2c在頂閥上室11 a之前分歧之排氣閥作動通路53。 該排氣閥作動通路53與排氣通路26之間設有第2實施形態 之排氣閥50。第2實施形態之排氣閥50亦與第1實施形態相 同’具備排氣活塞5 1與將其賦能於開放側之壓縮彈簧$ 2。 排氣活塞51之上面（圖中下面）面向排氣閥作動通路53。 如圖9所示’壓縮空氣未流入於排氣閥作動通路53内之 狀態（大氣開放狀態）下，排氣活塞5 1利用壓縮彈簧5 2之賦 能力保持在使排氣通路26開放之位置（從排氣通路26内退 避之位置）。與此相對，如圖10所示，壓縮空氣經由作動 空氣通路2c流入於排氣閥作動通路53内時，排氣活塞51利 用其空氣壓與壓縮彈簧52對抗’向進入於排氣通路26内之 擠壓位置（圖中上方）移動。排氣活塞51到達擠壓位置時排 氣通路26之有效通氣面積受擠壓，抑制活塞下室25之排氣 156792.doc -22· 201213067 效率。 根據該第2實施形態之排氣閥5 〇 ’螺絲緊固結束後解除 開關桿6之拉伸操作，藉此若觸發閥4()關閉，則如前述自 儲存槽3a向作動空氣通路_供給壓縮空氣。如此，作動 空氣通路2c内從與大氣相通狀態切換成壓縮空氣供給狀辑 時，壓縮空氣流入於頂閥上室lla内，關閉頂闕n，結果 停止向活塞上室12a之壓縮空氣之供給，且壓縮空氣亦流 入於從作動空氣通路2e分歧而設之排氣閥作動通路53内， 其結果排氣活塞51向擠壓側作動’成為排氣通路％受擠壓 之狀態。 若頂閥11下動並關閉，則其衝程軸部Ub與閥止動件14 分離，因此變成排氣孔15〜15與活塞上室12a連通之狀態， 其結果被關入於活塞上室12a内之壓縮空氣經由排氣孔 15〜15及止回閥16流入於回收空氣通路17内。流入於回收 空氣通路17内之壓縮空氣流入於活塞下室25内，使活塞12 及空氣馬達30上動，另一方面，其一部分經由排氣通路％ 向大氣排氣。於該階段，由於排氣通路26藉由排氣閥5〇而 被擠壓’因此變成適當抑制其排氣效率之狀態。因此，經 由回收空氣通路17流入於活塞下室25之回收空氣為使活塞 12及空氣馬達3〇返回至上死點僅消耗充分量，使活塞丨之及 工氣馬達30確實返回至上死點。 如此’螺絲緊固結束後利用用以關閉活塞上室l2a之壓 縮空氣’使排氣閥50作動於擠壓侧，藉此亦可確保充分量 之回收空氣，確實防止打入工具1之動作不良（活塞12等之 156792.doc -23- 201213067 返回不良），因此可使排氣通路26之有效通氣面積比先前 充分大，可實現先前有困難之高輸出。 圖11係顯示對第2貫施形態之打入工具丨進而加入變更之 第3實施形態之打入工具1。該第3實施形態之打入工具1在 具備使第2實施形態中之回收空氣通路17與排氣通路％合 流之構成之點上與第2實施形態不同。關於排氣閥5〇及其 他構成未變更’因此使用相同符號並省略其說明。 與第2實施形態相同，設有作動空氣通路以在頂上室Ua 之近前分歧之排氣閥作動通路53，該排氣閥作動通路53到 達排氣閥50。因此，若於螺絲緊固結束後對作動空氣通路 2c内供給壓縮空氣，使頂閥丨丨關閉，則與此同時排氣閥％ 之排氣活塞51於擠壓側作動，使排氣通路55之有效通氣面 積受擠壓。 第3貫施形態之情形中，設於上部基座部2g周圍之回收 空氣通路56與排氣通路55連通。關閉頂閥U且被關入於活 塞上至12a之壓縮空氣經由排氣孔15〜15及止回閥16流入於 回收空乳通路5 6 ’其後經由排氣通路5 5流入於活塞下室2 5 内’作為用以使活塞12及空氣馬達30返回至上死點之回收 空氣發揮作用。 與第2實施形態相同，於該時間點，利用排氣閥5〇擠壓 排氣通路55 ’因此在活塞12及空氣馬達30返回至上死點之 期間’成為適當抑制活塞下室25之排氣效率之狀態。活塞 12及空氣馬達3〇返回至上死點後，活塞下室25内之壓縮空 氣主要經由排氣通路55從大排氣口 45a向大氣排氣，最終 156792.doc -24- 201213067 活塞下至25、回收空氣通路56及排氣通路55成為與大氣相 通狀態。 只要作動空氣通路2c為壓縮空氣供給狀態，則排氣閥5〇 成為向擠壓側作動之狀態。因此在接著拉伸操作開關桿6 而打開觸發閥40之時間點，排氣閥5〇返回至開放側。 如此根據使回收空氣通路56與排氣通路55合流之第3實 施形態之構成，亦與第2實施形態㈣，藉由螺絲緊固結 束後使排氣閥50作動於擠壓側，適當抑制排氣效率，而可 確保充分量之回收空氣，藉此可防止該打入工具〗之動作 不良，可獲得螺絲打入時之高輸出。又，第3實施形態之 凊开/中可使回收空氣通路56與排氣通路55合流，發揮作 為通氣面積更大之合流通路之功能，因此可謀求通路配置 之簡化且可謀求更增大排氣通路，進一步高輸出化。 可對以上說明之第1〜第3實施形態進而加入變更。例如 作為打入工具1例示内裝空氣馬達3〇之打螺絲機，但對於 不具備此種空氣馬達之僅打擊作用之打入工具，例如打釘 機亦可同樣適用。又，雖例示具備將活塞上室之壓縮空氣 作為用以使活塞返回至上死點之回收空氣利用之排氣回收 結構之打入工具’但藉由應用對於具備活塞下動時（打入 工具打擊時）將供給於活塞上室之壓縮空氣儲存於回收空 氣室，將其作為活塞上動時之回收空氣加以利用之給氣回 收結構之打入工具所例示之排氣閥20、50，亦可獲得相同 之作用效果。 【圖式簡單說明】 156792.doc -25- 201213067 視Γ係本發明之第1實施形態之打入工具之内部結構之側 圖本圖顯示非作動狀態》 ^係第i實施形態之打U具之内部結構之側視圖。本 圖顯示利用開關桿之拉伸操作而觸發閥打開之瞬間狀態。 :3係第丨實施形態之打入工具之内部結構之側視圖。本 系顯不頂閥打開對活塞上室供給麼縮空氣，活塞及空氣 5一體下動，活塞到達其下死點之時間點之狀態。空氣 馬達係下動中途。 圖4係第旧施形態之打入工具之内部結構之側視圖。本 二係顯不空氣馬達一面旋轉至下死點，螺絲之緊固結束之 時間點之狀態。 圖5係第叆施形態之打入工具之内部結構之側視圖。本 圖係顯示解除開關桿之拉伸操作，使觸發閥_，藉此頂 閥關閉瞬間之狀態。該階段下排氣閥作動於擠壓侧。曰 圖6係第⑸施形態之打入工具之内部結構之側視圖。本 圖係顯示活塞及空氣馬達返回至上死點之中途狀態。於該 階段，排氣閥保持在擠壓位置。 圖7係放大顯示圖3之一部分之圖，係頂間周邊之内部放 大圖。本圖中，排氣閥保持在開放位置。 ^ 圖8係放大顯示圆6之一部分之圖，係頂閱周邊之内部放 大圖。本圖中，排氣閥保持在擠壓位置。 ° 圖9係第2實施形態之打入工具中，放大顯示頂闕周邊之 :部結構之側視圖。本圖係顯示活塞下動時(螺 時）’排氣閥保持在開放位置之狀態。 156792.doc • 26- 201213067 放大顯示頂閥周邊 上動時排氣閥保持 圖10係第2實施形態之打入工具中， 之内部結構之側視圖。本圖係顯示活塞 在擠壓位置之狀態。 圖11係第3實施形態之打入工具之内部結構之側視圖。 【主要元件符號說明】 1 打入工具 2 工具本體部. 2a 本體殼 2b 蓄壓室 2c 作動空氣通路 2d 排氣口 2e 中間基座部 2f 輔助通氣孔 2g 上部基座部 3 把手部 3a 儲存槽 3b 閥殼部 3c 閥殼孔 4 打入引導部 4a 打入通路 5 打入工具供給裝置 5a 空氣通路 5b 發送活塞 5c 壓縮彈簧 156792.doc -27- 201213067 5d 6 7 8 10 11 lia lib 12 12a 12b 12c 13 14 15 16 17 18 18a 19 20 21 22 23 發送爪 開關桿 起子頭 連結臂 打擊機構部 頂閥 頂閥上室 衝程軸部 活塞 活塞上室 活塞止動部 輔助通氣孔 壓縮彈簧 閥止動件 排氣孔 止回閥 回收空氣通路 氣缸 回收孔 前緩衝墊 排氣閥 排氣活塞 壓縮彈簧 作動孔 -28- 156792.doc 201213067 25 活塞下室 26 排氣通路 30 空氣馬達 31 衝程軸部 32 止動凸緣部 33 馬達空氣流入口 34 馬達殼部 34a 底板 35 縛片 36 輸出基座 36a、36b 軸承 36c 輸出齒輪 37 行星齒輪 37a 齒輪座 38 轴承 39 止動墊圈 40 觸發閥 41 閥門外框部 41a 第1空氣孔 41b 第2空氣孔 41c 大氣開放孔 42 閥内框部 43 閥門桿 43a 壓縮彈簧 156792.doc -29- 201213067 45 輸出模式切換刻度盤 45a 大排氣口 45b 止動裝置 50 排氣閥（第2實施形態） 51 排氣活塞 52 壓縮彈簧 53 排氣閥作動通路 55 排氣通路（第3實施形態） 56 回收空氣通路（第3實施形態） B 螺絲 W 緊固材 156792.doc -30-201213067 VI. Description of the invention: [Technical field to which the invention pertains] * Screw machine for operating with force Source The present invention relates to a compressed air as a driving tool. [Previous Technology·] Qiao Yushuo slammed the head of a screw that was driven into the guide, and the screw was tightened in the direction of the screw tightening. The inside of the screw was tightened with compressed air. The source is the body of the returning piston and the body of the rotating air motor. The above-described driving guide is provided at the front end of the tool body portion in the driving direction. The air motor and the piston-body move back and forth, and a screwdriver head is mounted on the output shaft. The front end of the screwdriver head reaches the driving guide. It is inserted into the guide portion, and is provided with a screw supply portion for the action of the hitting action of the main body of the tool, and a case for housing a plurality of screws. A handle portion that the user grips is provided on a side portion of the tool body portion, and a switch lever in a triggering manner in which the user operates with a fingertip is provided in the vicinity of the base portion of the handle portion. If the switch lever is extended, the air is supplied to the upper chamber of the piston of the tool body portion, and the piston is moved downward, and the air motor is rotated to complete the screw insertion. When the stretching operation of the switch lever is released, the compressed air supplied to the upper chamber side of the piston flows into the lower chamber side of the piston, and the piston and the air motor are integrally returned to the top dead center. A part of the retracted air (return air) flowing into the lower chamber side of the piston flows into the screw supply portion, and is used as a power source for screw transmission, and is mainly connected to the atmosphere through the exhaust passage. In such a screw machine, there is provided a function of switching the wood pattern of the 156792.doc 201213067 and the steel plate type for screwing the steel plate into the screw. In the above-mentioned wood-working mode, in order to reduce the reaction force at the time of driving, or to prevent the screw from being driven in (causing not only the air motor to screw the screw but also the nail to enter), the output is relatively low, On the other hand, in the latter's steel plate mode, the output is greater than the driving force of the wood-working mode. First, as a method for switching the manpower, in addition to the technique of switching the pressure of the compressed air supplied to the upper chamber of the piston, the following patent documents disclose that the output is performed by switching the exhaust efficiency of the lower chamber of the piston. The technology of switching modes. The money-transfer switching technique disclosed in the following patent document utilizes a principle that changes the exhaust efficiency when the diameter of the exhaust passage passing through the lower chamber of the piston changes, and the dynamic speed under the piston also changes. A rotating plate having two discharge ports is provided on the portion, and the position of the rotating plate is switched, and when the diameter of the discharge port of the exhaust passage is switched to a large diameter hole (steel plate mode), the exhaust efficiency of the lower chamber of the piston is improved. As a result, the speed of the piston is increased at a higher speed, and the striking force with respect to the screw is larger than that of the wood-working mode. When the position of the rotating plate is switched to the small diameter hole side (wooding mode), the diameter of the discharge port becomes a small diameter, and the exhaust efficiency of the lower chamber of the piston is lowered, and as a result, the moving speed below the piston becomes slow, and the striking force becomes small. The composition. Further, in the driving tool disclosed in the following patent document, the recovery air for returning the piston from the bottom dead center to the top dead center after the end of the driving is compressed by the generation of the striking force supplied to the upper chamber of the piston. Air exhaust recovery method. In the exhaust gas recovery method, not only the compressed air in the upper chamber of the exhaust piston but also the compressed air in the lower chamber of the piston is temporarily used, and the portion 156792.doc 201213067 - which is temporarily inflow into the lower chamber of the piston is used as the compressed air for the piston return. Then, the remaining compressed air is exhausted through the exhaust passage. [Prior Art Document] [Patent Document] [Patent Document 1] 曰本特开2006-983 公公民 [Summary of the Invention] [Problems to be Solved by the Invention] By using the gas recovery party in this way <, and the driving tool configured to switch the diameter of the exhaust passage to switch the output mode, and to increase the output limit of the previous steel plate mode. In the case of the exhaust gas recovery method described above, in order to increase the output of the exhaust passage and increase the exhaust efficiency in order to increase the output, the compressed air from the upper chamber of the piston to the lower chamber of the piston after the end of the injection is caused. After the (four) passage exhaust m' is driven, the recovery air for returning the piston to the top dead center is insufficient, and there is a malfunction that the piston cannot return to the top dead center. Therefore, in the configuration in which the exhaust gas recovery method has been used, there is a limit to achieving high output by the large diameter of the exhaust passage. " Therefore, the object of the present invention is to sufficiently ensure the recovery air in the lower chamber of the piston, for example, in the driving tool of the exhaust gas recovery method, and to increase the exhaust efficiency by making the secretary larger in diameter. The driving tool is higher in output 0 [Technical means for solving the problem] The above problem is solved by the following invention. The first invention is a driving tool which lowers the piston via the exhaust passage 156792. Doc 201213067 Room exhaust' and the piston is moved by the compressed air supplied to the upper chamber of the piston to generate the driving force, and the exhaust passage is opened when the piston moves under the piston, and the exhaust passage is squeezed when the piston moves. Exhaust Ke. According to the first aspect of the invention, the exhaust passage is made larger in diameter, and the exhaust efficiency of the lower chamber of the piston is increased, whereby the driving force can be increased. The exhaust passage utilizes the actuation of the exhaust valve to cause a change in the effective aeration area. When the exhaust passage is moved by the piston, the exhaust valve is actuated on the pressing side and has a small diameter. On the other hand, when the piston is actuated, the exhaust valve is actuated on the open side and has a large diameter. Therefore, even if the exhaust passage is made larger in diameter, the driving force is increased in output, and the exhaust valve is actuated after the completion of the driving, thereby squeezing the exhaust passage, so that the exhaust efficiency of the lower chamber of the piston can be appropriately suppressed. This allows the recovered air to flow sufficiently into the lower chamber to reliably return the piston to the top dead center. According to a second aspect of the invention, the driving tool of the first aspect of the invention includes an output mode switching mechanism that changes a diameter of an exhaust port of the exhaust passage by a manual operation to change the driving force. According to the second aspect of the invention, for example, by switching the production tray by the manual operation output mode and changing the size of the exhaust port, it is possible to switch the wood having a small driving force: ^ and the steel plate mode having a large driving force. In addition to the mode switching using the output mode switching mechanism, the one-time intake _ middle exhaust passage is squeezed at an appropriate timing by the exhaust gas shutoff, thereby obtaining a comparison under the plugging valve (4) On the other hand, when the piston moves up, it can ensure that the piston is pressed down to a sufficient amount to return to the second rolling, so as to avoid the malfunction of the driving tool. According to a third aspect of the invention, the second or second invention is provided with a venting singer. The exhaust gas recovery structure is such that the compression space supplied to the upper chamber of the piston is 156792. Doc 201213067 The return air passage flows into the lower chamber of the piston, and a part of it is used as the recovery air for returning the piston to the top dead center, and the rest is exhausted through the exhaust passage. According to the third aspect of the invention, in the driving tool having the exhaust gas recovery structure, the exhaust passage is squeezed when the piston is moved by the exhaust valve, thereby ensuring sufficient recovery of the air in the lower chamber of the piston and avoiding the driving tool. Since the operation is poor, it is possible to eliminate the previous limit by further increasing the diameter of the exhaust passage and increasing the output of the driving tool. According to a fourth aspect of the invention, the driving tool according to the third aspect of the invention is characterized in that the exhaust valve is operated in the direction of extrusion by the recovered air in the recovery air passage. According to the fourth aspect of the invention, in the driving tool including the exhaust gas recovery structure, after the completion of the driving, the recovery air is introduced into the lower chamber of the piston through the recovery air passage, and the exhaust valve is actuated on the pressing side. This is suppressed by the appropriate timing element into the exhaust efficiency of the lower chamber of the piston. According to a fifth aspect of the invention, there is provided the driving tool according to any one of the first to third aspect, comprising: a top valve that opens and closes the pressure accumulating chamber of the upper chamber of the piston, and the exhaust valve is actuated by the compressed air that closes the top valve Composed in the direction of pressure. According to the fifth aspect of the invention, the exhaust valve is operated on the pressing side instead of the recovered air in the empty rolling passage in the exhaust gas recovery structure, and the top valve is actuated on the closing side after the completion of the driving. The air causes the exhaust valve to actuate on the pressing side, whereby the exhaust efficiency of the lower chamber of the piston can be appropriately suppressed, and the piston can be returned to the top dead center with a sufficient amount of recovered air. This configuration is also applicable to a driving tool that does not have an exhaust gas recovery structure. The sixth invention is the driving tool of the third or fourth invention, wherein the exhaust passage I56792 is provided. Doc 201213067 Confluence with the recovery air passage. According to the sixth aspect of the invention, it is possible to simplify the passage structure as compared with a configuration in which the exhaust passage and the return air passage are provided independently of each other, and the exhaust passage can be made larger. The seventh invention is the so-called screwing machine according to any one of the first to sixth aspects, wherein the air motor is operated by compressed air, and the screw is tightened by a piston and the air motor is rotated to tighten the screw. . The configuration of any of the first to sixth inventions can be applied to the so-called screw machine. Therefore, the constitution of any of the inventions of the first to the fourth is also applicable to, for example, a compressed air type nailing machine which does not incorporate the driving tool of such an air motor. [Embodiment] An embodiment of the present invention will be described based on Fig. 1 to Fig. 1 . The figure shows the internal structure of the entire driving tool i of the first embodiment. The δ stomach-spinning screw machine is an air tool that is fastened to one side to hit a screw Β--the function of the material to be rotated in the direction of the screw tightening. The driving tool 1 includes a tool body portion 2, a handle portion 3, a driving guide portion 4, and a driving tool supply device 5. The tool main body portion 2 has a configuration in which a main body casing 2a having a substantially cylindrical shape is provided with a mechanism such as a striking mechanism portion _ air motor 30 described below. The handle portion 3 for gripping by the user is provided in a state of protruding from the side portion of the tool body portion 2 to the side. The front end side of the handle portion 3: the figure is not omitted. The tube stores compressed air inside the handle portion 3 by being connected to the front end of the handle portion 3 via a connector. Hereinafter, the area of the compressed air which is stored as the power source inside the handle °P 3 is referred to as the =B storage tank 3a and the striking mechanism portions 10 and 156792 on the inner side of the main body casing 2a. Doc 201213067 The accumulator chamber 2b partitioned around the air motor 30 is constantly connected. In the vicinity of the base of the handle portion 3, a switch lever 6 in a triggering manner in which the fingertip of the hand held by the user is pulled is provided, and a trigger valve 40 which is activated by the operation is provided. The compressed air is supplied to the tool body portion 2 side by the opening of the trigger valve 4 伴随 with the operation of the switch lever 6. The driving guide σρ 4 has a function of guiding the one screw b supplied into the driving path 4a to the driving member w by striking the screwdriver head 7, and is disposed downward from the lower portion of the tool body portion 2 (into the lower side) Material trade side) prominent state. The front end of the driving guide 4 is provided with a contact arm 8. The stretching operation of the switch lever 6 is effective only in a state where the contact arm 8 is pressed against the screw insertion portion, and the driving operation of the tool body portion 2 is completed, thereby preventing an inadvertent driving operation. The error prevention mechanism is previously known, and thus the detailed description is omitted. Further, the present embodiment has a feature in the exhaust structure of the tool main body portion 2, and the basic configuration of the striking mechanism portion 1A, the air motor 3A, the trigger valve 4, and the like is conventionally known, and is not required in the present embodiment. Special changes. Further, the driving guide unit 4 and the driving tool supply device 5 are also known in the prior art, and thus detailed description thereof will be omitted. Hereinafter, the configuration of each portion from the upstream side will be described along the flow of the compressed air supplied to the storage tank 3a. First, the trigger valve 40 is housed in the valve casing portion 3b provided at the base of the handle portion 3. The trigger valve 40 includes a valve outer frame portion 41, a valve inner frame portion 42, and a valve stem 43. The valve outer frame portion 41 is attached to the inside of the valve casing portion 3b so as not to be movable. The valve inner frame portion 42 is accommodated inside the valve outer frame portion 41 so as to be movable up and down. The inside of the valve inner frame portion 42 can be vertically moved to accommodate the valve 156792. Doc 201213067 Rod 43. The front end side of the valve stem 43 protrudes from the valve outer frame portion 41 1 to the lower side and collides with the rear surface of the switch lever 6. The air pressure of the storage tank 3 & often acts above the valve stem 43. The trigger valve 4 is closed in the non-actuated state in which the switch lever 6 is operated without stretching. In the closed state of the trigger valve 40, the actuating air passage 2c on the tool body portion 2 side passes through the valve housing hole 3c of the valve housing portion 3b and the valve outer frame portion 41! The air hole 41a, the valve outer frame portion 41 and the valve inner frame portion 42, and the second air hole 41b of the valve outer frame portion 41 communicate with the storage tank 3a, and the upper valve upper chamber 1 is moved via the actuating air passage 2c.丨 & supply compressed air status. The top valve 11 has a function of opening and closing the upper chamber 12a of the piston to the pressure accumulation chamber 2b, and is energized on the closing side by the compression spring 13. Therefore, in a state where compressed air is supplied to the top valve upper chamber 11a via the actuating air passage 2c, the air pressure cancels out between the compressed air acting on the open side accumulating chamber 2b, and as a result, the top valve 11 is compressed by the spring 13 Keep it in the off position. The top valve 丨丨 is kept in the closed state, and as a result, the compressed air is not supplied to the upper chamber 12a of the piston, so that the tool body portion 2 is kept in the non-actuated state. As shown in FIG. 2, when the switch lever 6 is pulled upward, the valve stem 43 is The air pressure of the compression spring 43a and the storage tank 3a moves upward against each other. When the valve rod 43 is moved, the air pressure of the reservoir groove 3a acts on the upper surface of the valve frame portion 42, so that the valve inner frame portion 42 is moved downward. When the valve inner frame portion 42 is moved downward, the actuating air passage 2c is cut off from the storage tank 3a, and the atmosphere opening hole 41c through the valve outer frame portion 4 is opened to the atmosphere. When the actuating air passage 2c is open to the atmosphere, the top valve upper chamber 11a is open to the atmosphere. Therefore, the top valve port is opened upward by the air pressure of the accumulator chamber 2b against the compression spring 13 . If the top valve is open, then 156792. Doc • 12- 201213067 The compressed air in the accumulator chamber 2b flows into the upper chamber 12a of the piston, which acts on the inner peripheral side of the piston 12, and the compressed air acts on the piston 12 in the downward direction. In addition, in Fig. 3, the flow of compressed air (supply and exhaust) is indicated by a blank arrow. The piston 12 starts to move downward by the compressed air flowing into the upper chamber 12a of the piston. If the piston 12 starts to move down, the air motor 3 开始 starts to move down with it. The lower side of the air motor 30 (the bottom plate 34 to be described later is airtightly housed in the air red 18 attached to the main body casing 2a. A front buffer 塾19 is attached to the lower portion of the cylinder 18. The inner peripheral side of the front cushion 19 is inserted. There is a screwdriver head 7. The lower side of the air motor 30 on the inner circumference side of the cylinder 18 corresponds to the piston lower chamber 25. The piston lower chamber 25 communicates with the atmosphere side via the inner peripheral side of the front cushion 19 and the exhaust passage %. 26 reaches the upper portion of the body casing 2a. In the present embodiment, the exhaust passage 26 is formed to have a larger diameter than the previous one, and the effective ventilation area is filled: the earth is formed, whereby the piston is moved downward (when the screw is driven) The efficiency is improved to obtain a large strike force that has not been previously obtained. On the upper portion of the body casing 2a, as an output mode switching mechanism, a disk-shaped output mode switching dial 45 is mounted. The output mode is switched on the dial 45. There is a large-diameter exhaust port 45a and a small-caliber exhaust (not shown in the figure). The straw is manually rotated by the user to switch the output mode to arbitrarily switch to the large exhaust port. At the upper end of the exhaust passage (Plate mode), + + + # $ $ / a state of the end (wood mode). This === the price of the ball of the steel ball on the exhaust passage 26 is maintained. :=, the output mode switching dial 45 is switched to the former, and the effective ventilation area of the exhaust passage 26 can be maintained as it is, i56792. Doc • J3· 201213067 and maintains the efficiency of discharge. Therefore, in the steel plate mode, a large striking force can be output in a steel plate work or the like. On the contrary, if the output mode switching dial 45 is switched to the latter woodworking mode, the exhaust passage % is squeezed at its outflow port, so that the effective ventilation area is reduced, and the exhaust efficiency is lowered, so that the mode is 5 In the following, the reaction force at which the striking force becomes small and the screw is pushed in can be suppressed, which can improve the operability of the driving tool 1. As shown, the exhaust passage 26 is interposed with an exhaust valve 2〇. The exhaust valve 2 has a function of reducing the effective ventilation area of the exhaust passage 26 by returning and reducing the exhaust efficiency, which is one of the features of this embodiment. Details of the exhaust valve 20 will be described later. The stroke shaft portion 31 of the air motor 30 is inserted into the inner peripheral side of the piston 12 so as to be movable up and down. A stopper flange portion 32 is provided at an upper end portion of the stroke shaft portion 31. Four motor air flow inlets 33 to 33 are provided on the lower side of the stopper flange portion 32. The compressed air which is opened by the top valve 11 and flows into the upper chamber 2a of the piston flows into the inner peripheral side of the stroke shaft portion 31 through the air inlets 33 to 33 of the motor. The air motor 30 starts to rotate by the compressed air flowing into the inner peripheral side of the stroke shaft portion 31 through the motor air inflow ports 3 3 to 3 3 . The air motor 3A includes a motor case portion 34 that is eccentric to the stroke shaft portion 31, and the inner peripheral side of the motor case portion 34 is provided to allow the output base 36 and the plurality of fins 35 to 35 to be displaced in the radial direction. The well-known composition. The output base 36 rotatably accommodates the motor casing portion 34 via the bearings 36a and 36b, and receives the fins 35 when the compressed air is introduced into the motor casing portion 34 via the inner peripheral side of the stroke shaft portion 31. The output base 36 is rotated, whereby the fins 35 are radiated 156792. Doc •14- 201213067 It is moved back and forth for air supply and exhaust. As shown in Fig. 3, the exhaust of the motor air is performed via the exhaust port 2 (1) provided at the side of the body casing 2a. An output gear 36c is formed at the lower end of the output base 36 of the air motor 30. The output gear 36c is coupled to the reduction planetary gear row 37. The gear carrier 37aJ1 of the planetary gear row 37 is mounted with a driver head 7. The gear carrier 37& is rotatably supported by the bottom plate 34& of the motor casing portion 34 via a bearing 38. The compressed air flowing into the upper chamber 12a of the piston, the piston 12 and the air motor 0 are moved downward, and the air motor 3 is rotated, whereby the screwdriver head 7 rotates the screw in the driving passage 4a in the fastening direction and moves downward. Thereby, one screw B supplied into the driving passage 4a is struck by the bit 7 and then rotated in the fastening direction to be fastened in the driving material. As shown in Fig. 3, the piston 12 and the air motor 3 are When the piston a moves downward and the piston a reaches the lower end position, the air motor 3 is separately moved downward. The piston stopper 12b provided around the upper portion of the piston bore abuts against the upper surface of the intermediate base portion k of the body casing 2a. , thereby limiting the position of the moving end below the piston 12. As shown in Figure 3 As indicated by the arrow, when the piston 12 reaches the lower end, the plurality of auxiliary vent holes 12c to 12c provided around the piston 12 coincide with the plurality of auxiliary vent holes 2f to 2f provided around the intermediate base portion, and thus the top valve u And the piston 12, the supply amount of the compressed air on the inner peripheral side is immediately increased, whereby the air motor 30 is individually lowered and starts to rotate with a high torque. As shown in Fig. 4, after the piston 12 is stopped, the air motor is used. 3〇 is moved downward alone, and the stop flange portion 32 of the upper end of the stroke shaft portion 31 abuts against the inner peripheral side of the piston, and the air motor 3 〇 also reaches the lower end position thereof. The flange 32 abuts against the inner peripheral side of the piston 12, and stops 156792. Doc •15· 201213067 The supply of compressed air from the upper chamber 12a of the piston to the air motor 3 stops the rotation of the air motor 30. At this point in time, the fastening of the screw 8 with respect to the fastening material W is completed. By operating the switch lever 6 as described above, the trigger valve 4 is opened, and compressed air is supplied to the upper chamber 12a of the piston, the piston 12 is moved downward, and the air motor 30 is rotated side by side with the piston 12, Thereafter, the motor is rotated downward with a high torque to reach the lower end position, thereby fastening one screw B supplied to the driving path 4a to the driving material w. As shown in FIG. 5, after the screwing is completed, if the user releases the stretching operation of the switch lever 6, the valve stem 43 of the trigger valve 40 is returned by the capacity of the compression magazine 43& and the air pressure in the storage tank 3a. To the closed position below. By returning the valve lever 43 to the closed position, the switch lever 6 is pressed and returned to the closed position. When the valve stem 43 is returned to the closed position, the storage tank 3a blocks the upper surface of the valve inner frame portion 42, and therefore the air pressure with respect to the upper storage tank 3a does not act, and as a result, the valve inner frame portion 42 utilizes the compression bomb.箦43a's ability to move up. When the valve inner frame portion 42 is moved, the valve inner frame portion 42 and the valve outer frame portion 41 are blocked from the atmosphere side (the atmosphere opening hole 41c), and the actuating air passage 2c is passed through the valve casing portion 3b. The valve housing hole 3c, the first air hole 41a of the valve outer frame portion 41, the valve outer frame portion 41 and the valve inner frame portion 42, and the second air hole 41b of the valve outer frame portion 41 communicate with the storage groove 3a. When the actuating air passage 2c communicates with the storage tank 33, the compressed air flows into the top valve upper chamber 1a via the actuating air passage 2c, and the top valve 下 is moved downward by the compression spring 丨3, whereby the upper chamber i2a and the pressure accumulating portion of the piston Block 2b side blocked, stop to 156792. Doc 201213067 The supply of compressed air to the upper chamber 12a of the piston. When the top valve 11 is closed, the compressed air enclosed in the upper chamber 12a of the piston is utilized as the recovery air for returning the piston 12 and the air motor 30 to the top dead center. Therefore, the driving tool 1 of the present embodiment is a driving tool of the exhaust gas recovery type. A cylindrical upper portion base portion 2g is provided on the upper portion of the body casing 2a. The top valve portion upper chamber 1a is partitioned by the upper base portion 2g. The stroke shaft portion 11b provided on the upper portion of the top valve 11 is vertically stroked and airtightly held on the inner peripheral side of the upper base portion 2g. A valve stopper 14 is attached to the upper portion of the upper base portion 2g above the stroke shaft portion 11b. A plurality of vent holes 15 to 15 are provided at the side of the upper base portion 2g on the lower side of the valve stopper 14. An annular check valve 16 is attached to the outer peripheral side of all of the exhaust holes 15 to 15. Further, the recovery air passage 17 communicates with the periphery of the upper base portion 2g. The check valve μ allows the flow of the compressed air from the inner peripheral side of the upper base portion 2g to the recovery air passage 经由7 via the vent holes 丨5 to 15 to block the flow of the compressed air in the opposite direction. As shown in FIG. 2 to FIG. 4, the 'top valve 11 is moved' and the upper piston chamber 123 is opened with respect to the accumulating to 2b, and becomes the stroke shaft portion 1b of the top valve 与 and the valve stopper 14 In the collision, the piston upper chamber 12a is in a state of airtight blocking of the exhaust holes 15 to 15. On the other hand, as shown in FIG. 5 and FIG. 5, the top valve u is moved downward, and the piston upper chamber 12a and the pressure accumulation chamber hole are blocked, and the stroke shaft portion 11b of the top valve u is separated from the valve stopper 14 The piston upper chamber 12a is in communication with the exhaust holes 15 to 15 side. Therefore, as indicated by the circle 5, the top valve u is moved downward, and the dust-reduced air which is closed to the piston 12a flows into the recovery air passage 17 via the exhaust holes 1$ to 15 and the check valve 16. 156792. Doc 201213067 The recovery air passage 17 communicates with the piston lower chamber 25 via a recovery hole 18a provided on the outer peripheral side of the front cushion 19 provided at the lower portion of the cylinder 18. Therefore, the compressed air that has flowed into the recovery air passage 17 from the upper piston chamber 12a via the exhaust holes 15 to 15 and the check valve 16 flows into the lower piston chamber 25 through the recovery air passage 17 and the recovery hole 18a. The compressed air (recovered air) flowing from the upper piston chamber 12a into the lower piston chamber 25 via the recovery air passage 17 acts on the bottom plate 34a of the air motor 3, whereby the final piston 12 and the air motor 30 return from the bottom dead center to the top dead center. . As shown in Fig. 6, after the air motor 39 starts to move up, part of the recovered air immediately flows into the exhaust passage 26 through the inner peripheral side of the front cushion 19 and is exhausted. Here, the exhaust valve 20 is provided on the exhaust passage 26 as described above. Details of the exhaust valve 20 are shown in Figs. 7 and 8. According to the first embodiment, the exhaust valve 20 is provided between the recovery air passage π and the exhaust passage 26. The exhaust valve 20 of the first embodiment includes the exhaust piston 21 and the compression spring 22. The middle portion is movably supported in a left-right direction at a position protrudingly pressed into the exhaust passage 26 as shown in FIGS. 5, 6, and 8, and is exhausted from the exhaust passage 26 as shown in FIGS. 4 to 4 and 7. Exit between open positions. When the exhaust piston 2 is moved to the former pressing position, the effective ventilation area of the exhaust passage 26 becomes small, and the exhaust efficiency is lowered. When the exhaust piston 21 is moved to the latter open position, the effective ventilation area of the exhaust passage 26 is increased, and the exhaust efficiency is improved. The exhaust piston 21 is energized by the compression spring 22 to the open position side of the open exhaust passage %. The air pressure of the recovery air passage 17 is applied to the upper surface of the exhaust piston 21 (the left side in the drawing) via the operating hole 23. As shown in Figure 7, the compression is empty 156792. Doc -18- 201213067 In a state where the gas does not flow into the return gas passage 17, the exhaust gas (4) is held at the open position by the dust-reducing spring 22, so that the exhaust gas efficiency of the exhaust passage is kept high. On the other hand, as shown in Fig. 8, the closed valve U is closed, and the compressed air that has been placed in the upper chamber 12a of the piston enters the recovery air passage 17 via the exhaust hole 157 and the check valve (10), and the air pressure thereof is actuated. The hole acts on the exhaust piston 21', whereby the exhaust piston 21 opposes the compression spring 22 and moves to the pressing position. Therefore, if the recovery air is supplied from the upper piston chamber 12a to the lower piston chamber 25 via the recovery air passage 17, (4) At the same time, the exhaust valve 2 is called on the pressing side, and the exhaust passage 26 is pressed to suppress the state of exhaust efficiency. Thus, the exhaust passage 26 is formed to have a larger diameter than the previous one, thereby improving the exhaust efficiency. It is possible to output a large striking force that has not been previously obtained. On the other hand, the striking, ', σ beam becomes a state in which the exhaust gas efficiency of the exhaust passage 26 is suppressed by the exhaust valve 2G'. Therefore, the recovered air flows into the lower chamber 25 of the piston. Most of the piston 12 and the air motor 3 are consumed by returning to the top dead center, so the piston 12 and the air motor 30 are surely returned to the top dead center. As shown in Fig. 5, if the recovered air flows into the lower chamber of the piston, It acts on the bottom plate 34 of the air motor 30 By the difference in area between the bottom plate 34a and the upper surface of the stroke shaft portion 31, first, the air motor 3 is moved up by the air pressure on the side of the recovery air chamber 25. As shown in Fig. 6, if the air motor 3 is moved to the piston 12 When the stopper flange portion 32 is separated from the inner peripheral side surface of the piston 12, the upper piston chamber 12a communicates with the inner peripheral side of the stroke shaft portion 31 via the motor air flow inlets 33 to 33, whereby the upper piston chamber 12a passes through the motor. The air supply path and the exhaust port 2 (1 are connected to the atmosphere. On the other hand, the recovered air flowing into the piston through the recovery air passage 17 to 25 is prevented from being reversed to the upper chamber 12a by the check valve μ. Doc -19- 201213067 Stream. Thus, the upper piston chamber 12a is open to the atmosphere, and on the other hand, the recovered air flows into the lower piston chamber 25, whereby the air motor 30 is further moved upward. Further, one of the compressed air (motor exhaust) flowing from the upper piston chamber 12a to the motor air supply passage via the motor air inlets 33 to 33 acts on the lower surface of the piston 12, so that the piston 12 starts to move upward at this point of time. In the state shown in Fig. 6, the stopper washer 39 provided around the stroke shaft portion of the air motor 3 is abutted against the lower surface of the intermediate base portion 2e, and the air motor 30 reaches the top dead center. Thus, the air motor 3 〇 returning to the top dead center, while the piston 12 is moved up by the motor exhaust, and finally the air motor 3 〇 the stop washer abuts against the lower side, the upper air motor 3 〇 presses M, thereby returning to the top dead center The recovered air flowing into the lower chamber of the piston 2 is discharged to the atmosphere from the large exhaust port 45a of the output mode switching dial 45 via the exhaust passage 26, and also passes through the inner peripheral side of the front cushion 丨9. The exhaust gas is discharged to the atmosphere. The recovered air in the lower piston chamber 25 is discharged to the atmosphere. As a result, when the air pressure in the recovery air passage 17 is lowered, the exhaust piston 21 is returned to the open position by the compression spring 22, and the exhaust valve 20 is returned to The initial position. Further, the air passage that is driven into the tool supply device 5 "connects with the recovery air passage 17. Therefore, after the completion of the driving as shown in Fig. 5, a part of the compressed air that has flowed into the recovery air passage 17 from the upper chamber of the piston is supplied to the driving tool supply device 5 via the air passage h. The piston 5b transmitted by the compressed air supplied via the air passage & is opposed to the compression spring 5c and retracted. When the recovered air in the piston lower chamber 25 is exhausted, the transmitting piston 5b advances by compressing the elastic crystal 5c. The transmitting piston 5b is provided with a transmitting claw 5d, and if the transmitting piston is 156792. Doc •20· 201213067 When going forward, one screw B is supplied into the driving path 4a by the transmission claws 5d and 5d. According to the driving tool 1 of the first embodiment configured as described above, the exhaust passage 26 forms an exhaust efficiency higher than the previous large diameter 'the lower piston chamber 25, so that the steel plate having a thicker plate thickness can be screwed into the screw B at a high output. . And an exhaust valve 20 is interposed in the fluorine discharge passage 26. The exhaust valve 2A has a function of changing the effective ventilation area of the exhaust passage 26. The exhaust valve 20 is moved to the open position when the screw is moved downward (when tightening), and the effective ventilation area of the discharge passage 26 is enlarged, thereby improving the exhaust efficiency of the lower piston chamber 25 and completing the exhaust. On the other hand, when the piston is moved up, the piston is moved to the pressing position, and the effective ventilation area of the exhaust passage 26 is reduced, thereby suppressing the exhaust efficiency of the piston lower chamber 25, thereby ensuring sufficient The recovered air for returning the piston 12 and the air motor 3 to the top dead center 'prevents the malfunction of the driving tool 1. As described above, in order to avoid the shortage of the recovered air after the completion of the striking, the exhaust passage has a large diameter and the exhaust efficiency of the lower chamber of the piston is limited. However, according to the driving tool i of the present embodiment, the inspection is sufficiently ensured. In the air, it is possible to increase the output of the exhaust passage 26 with a larger diameter, and thus the above-mentioned limit can be eliminated. 'It can be fixedly switched by the above-mentioned exhaust valve 45' and 'effectively ventilating the gas passage of the dialing mode according to the driving tool 1 2 〇 separate rotation operation output mode of the present embodiment _ only, 柯μ arbitrary, high selection The output of the steel plate mode and the low output wood mode. In any case, the exhaust valve is actuated at a certain timing (when the piston is moved up after the end of the striking), so it can be fully green back to 156792. Doc -21- 201213067 The air is collected so that the piston 12 and the air motor 3〇 are indeed returned to the top dead center, so there will be no malfunction. The first embodiment described above can be implemented by adding various modifications. For example, although the exhaust gas in the exhaust gas passage 17 in the exhaust gas recovery structure is used to exemplify the operation of the exhaust valve 20 on the pressing side, it is also possible to use the closing top valve after the end of the driving. The compressed air is actuated on the side of the crucible, and the exhaust valve 50 is actuated on the pressing side. The driving tool of the second embodiment is shown in Figs. 9 and 10 . The driving tool of the second embodiment relates to the configuration and the first of the exhaust valve 50! The other embodiments are the same as the first embodiment, and the description thereof will be omitted by the same reference numerals. In the case of the second embodiment, as shown in Figs. 9 and 1B, the exhaust valve actuating passage 53 in which the actuating air passage 2c is branched before the top valve upper chamber 11a is provided. An exhaust valve 50 of the second embodiment is provided between the exhaust valve actuating passage 53 and the exhaust passage 26. The exhaust valve 50 of the second embodiment is also provided in the same manner as the first embodiment, and includes an exhaust piston 5 1 and a compression spring $ 2 that is energized to the open side. The upper surface (lower side in the figure) of the exhaust piston 51 faces the exhaust valve actuation passage 53. As shown in Fig. 9, in the state in which the compressed air does not flow into the exhaust valve actuating passage 53 (atmospheric open state), the exhaust piston 51 is held at a position where the exhaust passage 26 is opened by the biasing force of the compression spring 52. (a position to be retracted from the inside of the exhaust passage 26). On the other hand, as shown in FIG. 10, when the compressed air flows into the exhaust valve actuating passage 53 via the actuating air passage 2c, the exhaust piston 51 is opposed to the compression spring 52 by its air pressure to enter the exhaust passage 26. The extrusion position (upper in the figure) moves. When the exhaust piston 51 reaches the pressing position, the effective venting area of the exhaust passage 26 is squeezed to suppress the exhaust of the lower chamber 25 of the piston 156792. Doc -22· 201213067 Efficiency. According to the exhaust valve 5 〇 ' of the second embodiment, the tightening operation of the switch lever 6 is released after the screw fastening is completed, and when the trigger valve 4 () is closed, the self-storage tank 3a is supplied to the actuating air passage as described above. Compressed air. As described above, when the inside of the actuating air passage 2c is switched from the atmosphere-on state to the compressed air supply state, the compressed air flows into the top valve upper chamber 11a, and the top cymbal n is closed, so that the supply of compressed air to the upper chamber 12a of the piston is stopped. Further, the compressed air also flows into the exhaust valve actuating passage 53 which is branched from the actuating air passage 2e. As a result, the exhaust piston 51 is actuated toward the pressing side, and the exhaust passage is compressed. When the top valve 11 is moved down and closed, the stroke shaft portion Ub is separated from the valve stopper 14, and thus the vent holes 15 to 15 are in communication with the upper piston chamber 12a, and the result is locked in the upper chamber 12a of the piston. The compressed air therein flows into the recovery air passage 17 through the exhaust holes 15 to 15 and the check valve 16. The compressed air that has flowed into the recovery air passage 17 flows into the lower piston chamber 25 to move the piston 12 and the air motor 30, and a part thereof is exhausted to the atmosphere via the exhaust passage %. At this stage, since the exhaust passage 26 is pressed by the exhaust valve 5', it becomes a state in which the exhaust efficiency is appropriately suppressed. Therefore, the recovered air that has flowed into the lower chamber 25 of the piston through the recovery air passage 17 consumes a sufficient amount to return the piston 12 and the air motor 3 to the top dead center, so that the piston motor and the working motor 30 are surely returned to the top dead center. Thus, after the completion of the screw fastening, the exhaust valve 50 is actuated on the pressing side by the compressed air for closing the upper chamber l2a of the piston, thereby ensuring a sufficient amount of recovered air, and surely preventing the malfunction of the driving tool 1. (Piston 12, etc. 156792. Doc -23- 201213067 returns bad, so the effective ventilation area of the exhaust passage 26 can be made sufficiently larger than before to achieve a high output that was previously difficult. Fig. 11 is a view showing the driving tool 1 of the third embodiment in which the driving tool of the second embodiment is added. The driving tool 1 of the third embodiment differs from the second embodiment in that it has a configuration in which the collected air passage 17 and the exhaust passage % are combined in the second embodiment. The exhaust valve 5 〇 and other configurations are not changed. Therefore, the same reference numerals are used and the description thereof is omitted. As in the second embodiment, an exhaust valve actuating passage 53 is provided which actuates the air passage to be branched in the vicinity of the top chamber Ua, and the exhaust valve actuating passage 53 reaches the exhaust valve 50. Therefore, if the compressed air is supplied to the actuating air passage 2c after the screw fastening is completed, and the top valve 丨丨 is closed, the exhaust valve 51 of the exhaust valve % is actuated on the pressing side to make the exhaust passage 55. The effective ventilation area is squeezed. In the case of the third embodiment, the recovery air passage 56 provided around the upper base portion 2g communicates with the exhaust passage 55. The compressed air that closes the top valve U and is closed to the piston to 12a flows into the recovery empty milk passage 5 6 through the exhaust holes 15 to 15 and the check valve 16 and then flows into the lower chamber of the piston via the exhaust passage 5 5 . 2 5 ' acts as a recovery air for returning the piston 12 and the air motor 30 to the top dead center. As in the second embodiment, at this point of time, the exhaust passage 55' is pressed by the exhaust valve 5'. Therefore, during the period in which the piston 12 and the air motor 30 return to the top dead center, the exhaust of the lower chamber 25 is appropriately suppressed. The state of efficiency. After the piston 12 and the air motor 3 are returned to the top dead center, the compressed air in the lower piston chamber 25 is mainly exhausted from the large exhaust port 45a to the atmosphere via the exhaust passage 55, and finally 156792. Doc -24- 201213067 The piston down to 25, the recovery air passage 56 and the exhaust passage 55 are in an open state. When the operating air passage 2c is in the compressed air supply state, the exhaust valve 5 is in a state of being actuated toward the pressing side. Therefore, at the time when the operation of the switch lever 6 is subsequently stretched and the trigger valve 40 is opened, the exhaust valve 5 is returned to the open side. According to the configuration of the third embodiment in which the recovery air passage 56 and the exhaust passage 55 are merged, in the second embodiment (fourth), after the screw fastening is completed, the exhaust valve 50 is actuated on the pressing side, and the discharge is appropriately suppressed. The gas efficiency ensures a sufficient amount of recovered air, thereby preventing the malfunction of the driving tool and obtaining a high output when the screw is driven. Further, in the third embodiment, the recovery air passage 56 and the exhaust passage 55 can be combined to form a function as a merge passage having a larger ventilation area. Therefore, it is possible to simplify the arrangement of the passages and to increase the arrangement. The gas passage is further increased in output. The first to third embodiments described above can be further modified. For example, as the driving tool 1, a screwing machine incorporating a built-in air motor 3 is exemplified, but a driving tool that does not have such a blow action as the air motor, for example, a nailing machine can be applied in the same manner. Further, although the driving tool having the exhaust gas recovery structure in which the compressed air in the upper chamber of the piston is used as the recovery air for returning the piston to the top dead center is exemplified, the application is directed to the lowering of the piston. When the compressed air supplied to the upper chamber of the piston is stored in the recovery air chamber, the exhaust valve 20, 50 exemplified as the driving tool for the gas recovery structure, which is utilized as the recovered air when the piston is moved up, may also be used. Get the same effect. [Simple description of the diagram] 156792. Doc -25 - 201213067 The side view of the internal structure of the driving tool according to the first embodiment of the present invention is shown in the figure. The figure shows the side view of the internal structure of the U-shaped device in the i-th embodiment. This figure shows the moment when the trigger valve is opened by the stretching operation of the switch lever. : 3 is a side view of the internal structure of the driving tool of the third embodiment. The system does not open the valve to open the upper chamber of the piston to supply the air, the piston and the air 5 move downward, and the piston reaches the state of the bottom dead center. The air motor is moving halfway. Fig. 4 is a side view showing the internal structure of the driving tool of the first embodiment. This second series shows the state of the time when the air motor is rotated to the bottom dead center and the screw is tightened. Figure 5 is a side elevational view of the internal structure of the driving tool of the first embodiment. This figure shows the release operation of the release lever to trigger the valve _, thereby the state in which the top valve is closed. At this stage, the exhaust valve is actuated on the pressing side. Fig. 6 is a side view showing the internal structure of the driving tool of the (5)th embodiment. This figure shows the return of the piston and air motor to the middle of the top dead center. At this stage, the exhaust valve remains in the squeezed position. Fig. 7 is an enlarged view showing a portion of Fig. 3, showing an internal enlarged view of the periphery between the tops. In this figure, the exhaust valve remains in the open position. ^ Fig. 8 is an enlarged view of a portion of the circle 6, which is an internal enlarged view of the periphery. In this figure, the vent valve is held in the squeeze position. Fig. 9 is a side view showing the structure of the top of the top cymbal in the driving tool of the second embodiment. This figure shows the state in which the exhaust valve is kept in the open position when the piston is moved down (spiral time). 156792. Doc • 26-201213067 Enlarged display of the vicinity of the top valve Exhaust valve holding during the up movement Fig. 10 is a side view showing the internal structure of the driving tool of the second embodiment. This figure shows the state of the piston in the squeeze position. Fig. 11 is a side view showing the internal structure of the driving tool of the third embodiment. [Main component symbol description] 1 Driving tool 2 Tool body. 2a main body casing 2b accumulator chamber 2c actuating air passage 2d exhaust port 2e intermediate base portion 2f auxiliary vent hole 2g upper base portion 3 handle portion 3a storage tank 3b valve casing portion 3c valve casing hole 4 driving guide portion 4a The inlet passage 5 is driven into the tool supply device 5a. The air passage 5b sends the piston 5c to compress the spring 156792. Doc -27- 201213067 5d 6 7 8 10 11 lia lib 12 12a 12b 12c 13 14 15 16 17 18 18a 19 20 21 22 23 Sending claw switch lever screwdriver head connecting arm striking mechanism top valve top valve upper chamber stroke shaft piston Piston upper chamber piston stop auxiliary vent compression spring valve stop vent hole check valve recovery air passage cylinder recovery hole front cushion exhaust valve exhaust piston compression spring actuating hole -28- 156792. Doc 201213067 25 Piston lower chamber 26 Exhaust passage 30 Air motor 31 Stroke shaft portion 32 Stop flange portion 33 Motor air inlet 34 Motor housing portion 34a Base plate 35 Baffle 36 Output base 36a, 36b Bearing 36c Output gear 37 Planet Gear 37a Gearing 38 Bearing 39 Stop washer 40 Trigger valve 41 Valve outer frame portion 41a First air hole 41b Second air hole 41c Atmospheric opening hole 42 In-valve frame portion 43 Valve rod 43a Compression spring 156792. Doc -29- 201213067 45 Output mode switching dial 45a Large exhaust port 45b Stop device 50 Exhaust valve (2nd embodiment) 51 Exhaust piston 52 Compression spring 53 Exhaust valve actuating path 55 Exhaust path (3rd (Embodiment) 56 Recovery air passage (3rd embodiment) B Screw W Fastener 156792. Doc -30-