201207273 六、發明說明： 【發明所屬之技術領域】 本發明係有關於一種撓性咬合式齒輪裝置。 【先前技術】 專利文獻1之撓性咬合式齒輪裝置，具備：具有剛性 的內齒輪；外齒輪，具有可內咬合於該內齒輪的可撓性； 及震盪體，藉由使該外齒輪於本身外周彎曲變形來實現前 述內齒輪與外齒輪之內咬合。並且，專利文獻1中，使外 齒輪彎曲變形的震盪體之外周形狀成爲連接不同的2個曲 率半徑的圓弧的形狀。另外，在其震盪體中，於2個圓弧 之連接部份共用切線。因此，於專利文獻1中，能夠將外 齒輪的曲率半徑之變化控制在最小限度並防止外齒輪之彎 曲應力之增大，從而能夠謀求提高傳遞扭矩。 專利文獻1:日本特開2009-299765號公報 【發明內容】 (本發明所欲解決之課題） 在專利文獻1中’著眼於外齒輪之齒形形狀和短軸部 (內齒輪和外齒輪未咬合的圓弧部）中的外齒輪之應力來 決定震盪體中2個圓弧之連接部份。在此，短軸部由規定 內齒輪和外齒輪所咬合之範圍的咬合角度Θ和震盪體（外 齒輪）之偏心量L決定。但是，例如當角度θ小且偏心量l 小時，在專利文獻1中，也還帶來於短軸部產生內齒輪與 -5- 201207273 外齒輪之齒形干涉的危險。亦即，僅以角度Θ和偏心量L的 2個參數很難對外齒輪之齒形形狀、短軸部中的外齒輪之 應力及內齒輪和外齒輪之齒形之干涉這3個課題找出最佳 値。 另外’即便是幾何學上無齒形干涉之狀態，亦有可能 因基於負載扭矩的外齒輪之變形，於（短軸部中之）設想 外的位置產生齒形之干涉。因此，確保內齒輪與外齒輪之 非咬合範圍，以便於短軸部中內齒輪與外齒輪之間隙盡可 能變大爲較佳方式。 另外，爲了避免上齒形之干涉，亦能考慮切割內齒輪 的齒頂。但是，此時，產生內齒輪和外齒輪之咬合數減少 這樣的問題。 由此，本發明是爲了解決前述問題點而完成的，其課 題在於提供一種盡可能抑制由外齒輪之變形引起的彎曲應 力來避免由外齒輪之變形引起的內齒輪與外齒輪之齒形之 干涉，從而實現負載扭矩增大之撓性咬合式齒輪裝置。 (用以解決課題之手段） 本發明藉由如下解決前述課題，一種撓性咬合式齒輪 裝置，具備：具有剛性的內齒輪；外齒輪，具有可內咬合 於該內齒輪的可撓性；及震盪體’藉由使該外齒輪於本身 外周彎曲變形來實現前述內齒輪與外齒輪之內咬合，其中 ，前述震盪體之前述外周形狀爲依序連接將前述內齒輪和 外齒輪設爲咬合狀態且爲圓弧形狀的第1曲線部、曲率半 201207273 徑小於該第1曲線部的第2曲線部、及曲率半徑大於該第1 曲線部且將該內齒輪和外齒輪設爲非咬合狀態的第3曲線 部的形狀，並且，於該第1曲線部、第2曲線部及第3曲線 部的連接部份中’分別共用該第1曲線部、第2曲線部及第 3曲線部之切線。 本發明中，藉由3個曲線部構成震盪體，增加決定短 軸部的參數之數量且避免齒形之干涉。在本發明中’震盪 體之外周形狀具體成爲將圓弧形狀之第1曲線部、第2曲線 部及第3曲線部依序連接起來的形狀。亦即，曲率半徑小 於將內齒輪和外齒輪設爲咬合狀態的第1曲線部的第2曲線 部配置於第1曲線部與曲率半徑大於第1曲線部的第3曲線 部之間。因此，與僅將第3曲線部直接連接於第1曲線部時 相比，能夠以更短的（旋轉）距離將內齒輪和外齒輪從咬 合狀態設爲非咬合狀態。此時，能夠任意決定第2曲線部 之曲率半徑。亦即，與以往技術相比，能夠進一步確實地 避免齒形之干涉。 同時，本發明中，由於各曲線部之曲率半徑限制於各 曲線部內，所以降低各曲線部中外齒輪之彎曲應力。並且 ，由於在第1曲線部、第2曲線部及第3曲線部之連接部份 分別共用第1曲線部、第2曲線部及第3曲線部之切線，所 以，防止震盪體之連接部份中急劇的彎曲變形。亦即，能 夠盡可能抑制由外齒輪變形引起的彎曲應力，並能夠提高 傳遞扭矩。 另外，若以一定的曲率半徑規定第2曲線部，則可簡 201207273 化規定震盪體之形狀的參數。因此，能夠有效地設計撓性 咬合式齒輪裝置。 根據本發明盡可能抑制由外齒輪的變形引起的彎曲應 力來避免由外齒輪之變形引起的內齒輪和外齒輪的齒形之 干涉，從而實現負載扭矩之增大。 【實施方式】 以下，參照附圖詳細說明本發明之第1實施形態之一 例。 首先，主要利用第1圖至第4圖槪略說明本實施形態之 整體結構。 撓性咬合式齒輪裝置100，具備有：具有剛性的減速 用內齒輪（內齒輪）13 0A;外齒輪12 0A，具有可內咬合 於減速用內齒輪13 0A的可撓性；及震盪體104，藉由使外 齒輪12 0A於本身外周彎曲變形來實現減速用內齒輪i30A 與外齒輪120A之內咬合。在此，如第4圖所示，震盪體104 之外周形狀（與軸向Ο正交的剖面中的外周形狀）爲將不 同的3個曲率半徑rl、r2、r3的圓弧部（第1圓弧部FA、第 2圓弧部SA'第3圓弧部TA)依序連接在一起的形狀。並 且’分別共用各圓弧部（第1圓弧部FA、第2圓弧部SA、 第3圓弧部TA)之連接部份C、E中的切線ΤΙ、T2。 以下’對各構成元件進行詳細說明。 如第3圖（A)及（B)所示，震盪體104爲柱形狀，其 中央形成有插入未圖示輸入軸的輸入軸孔106。當輸入軸 -8 - 201207273 被插入並旋轉時，在輸入軸孔106 ’設置有鍵槽！〇8’以便 震盪體104與輸入軸一體旋轉。 在此，如第3圖（A)所示’若使震盪體104之旋轉中 心位於XY座標之中心，則震盪體104之外形於X軸和Y軸兩 方成爲軸對稱的形狀。因此’以下利用第4圖僅對震盪體 1 04之第1象限之形狀進行說明。 如第4圖所示，震盪體104之外周形狀由將3個圓弧部 (第1圓弧部FA、第2圓弧部SA、第3圓弧部TA)連接在一 起的形狀（3個圓弧形狀）構成。第1圓弧部FA (第1曲線 部）爲以點A (稱爲偏心軸）爲中心的曲率半徑r 1之圓弧 ，構成將外齒輪1 2 0 A和減速用內齒輪1 3 0 A設爲咬合狀態 的圓弧部（亦稱爲咬合範圍）。第2圓弧部SA (第2曲線部 )是以離開點A的距離ΔΙΙ的點D爲中心的曲率半徑r2之圓 弧，構成將外齒輪120A和減速用內齒輪130A設爲非咬合 狀態的圓弧部（亦稱爲非咬合範圍）之一部份。距離ΔΙΙ最 終爲用於決定非咬合範圍（短軸部）中外齒輪120A與減速 用內齒輪130A之間隙的變數。第3圓弧部TA (第3曲線部 )是以點F爲中心的曲率半徑r3之圓弧，構成將外齒輪 1 20 A和減速用內齒輪1 3 0 A設爲非咬合狀態的圓弧部（非 咬合範圍之其他範圍）。第1圓弧部FA之長度是由長軸方 向X與點c處的切線法線所成的角度亦即咬合角度e丨來決定 。第2圓弧部SA之長度是從長軸方向X與點E處的切線法線 所成的角度Θ2減去咬合角度Θ1的角度來決定（Θ2>Θ1)。因此 ’點A ' D、F之各座標以L爲偏心量，在第4圖中分別成爲 201207273 (L，Ο)、（L +AR* co sθ 1，△ R * siηθ 1 )、 (0，-(L + AR*cosei)*tane2 +^R*sin01 卜 亦即，若在長軸方向X，從震盪體104之旋轉中心（咬 合範圍中的）到震盪體104之外周上之點B的距離r (震盪 體1 04之長軸半徑），則如第4圖所示，由式（1 )表示第1 圓弧部FA之曲率半徑rl。 r 1 = r — L ··· (1) 另外，如第4圖所示，由式（2)表示第2圓弧部SA之 曲率半徑r2。 r 2 = r 1 — Δ R = r — L —厶 R ··· (2) 另外，在第1圓弧部FA和第2圓弧部SA之連接部份C處 共用切線T 1。 另外，如第4圖所示’在第2圓弧部SA和第3圓弧部TA 之連接部份E處亦共用切線T2。並且，第3圓弧部TA之曲 率半徑r3爲（曲率半徑r2 +長度DF ) ’所以由式（3 )表示 曲率半徑r3。 r3=r—L -厶 R+ (L + AR*cos61) /cos02 …（3) 其中，由於角度Θ2大於角度Θ1 ’所以式（4)成立。 r2<rl<r3·.· (4) 如第2圖所示，震盪體軸承1 10A爲配置於震盪體104之 外側與外齒輪1 2 0 A內側之間的軸承。如第2圖、第5圖所示 ，震遺體軸承包括內圈112、保持器114A、作爲轉動 體的滾子116A及外圈118A。內圈112之內側與震盪體104 抵接、且內圈112與震盪體104 —體變形的同時進行旋轉。 -10- 201207273 滾子1 1 6 A爲圓筒形狀（包括滾針）。因此，與轉動體爲滾 珠時相比’由於滾子116A中與內圈112及外圏118A接觸的 部份增大’所以能夠加大負載容量。亦即，藉由利用滾子 116A’可以增大震盪體軸承11〇a之傳遞扭矩且能夠使之 長壽命化。外圈1 1 8 A配置於滾子1 1 6 A之外側。外圈1 1 8 A 通過震盪體1 04之旋轉彎曲變形，使配置於其外側的外齒 輪120A變形。 另外’如第2圖所示，震盪體軸承110B與震盪體軸承 110A相同，包括內圈112、保持器114B、滾子116B及外圈 118B。內圈112於震盪體軸承110A、110B中是共用的。並 且’保持器1MB、滾子116B及外圈118B是與保持器114A 、滾子1 16A及外圈1 18A分別在軸向〇上配置2個且分別爲 同一形狀。以後，將震盪體軸承110A、110B統稱爲震盪體 軸承1 1 0。 如第1圖、第2圖所示，外齒輪120A與減速用內齒輪 130A內咬合。外齒輪120A包括基礎構件122和外齒124A❶ 基礎構件1 22爲具有可撓性的筒狀構件，配置於震盪體軸 承1 10A之外側且與外齒124A成型爲一體。外齒124A是根 據次擺線曲線成型。 如第1圖、第2圖所示，外齒輪120B是與輸出用內齒輪 130B內咬合。並且，外齒輪120B與外齒輪120A相同，包 括基礎構件122和外齒124B。外齒124B和外齒124A爲相同 數量，並且成型爲同一形狀。在此，如第1圖所示，外齒 1 2 4 A和外齒1 2 4 B爲在軸向0上被分割的形態，但基礎構件 -11 - 201207273 122是共用的。因此，震盪體104之偏心量L以同相位傳至 外齒1 2 4 A和外齒1 2 4 B。以後，分別將外齒輪1 2 0 A、1 2 0 B 及外齒124A、124B統稱爲外齒輪120及外齒124。 減速用內齒輪1 3 〇 A由具有剛性的構件形成。減速用內 齒輪130A具備比外齒輪120A之外齒124A之齒數僅多i ( i = 2 、4、…）片的齒數。減速用內齒輪130A中，透過螺栓孔 132A固定未圖示的外殼。並且，減速用內齒輪130A藉由 與外齒輪120A咬合而有助於震盪體104旋轉之減速。減速 用內齒輪130A之內齒128A成型爲與基於次擺線曲線的外 齒124A理論咬合。 另一方面，輸出用內齒輪130B亦與減速用內齒輪130A 相同，由具有剛性的構件形成。輸出用內齒輪1 30B具備與 外齒輪120B之外齒124B之齒數相同的內齒128B之齒數（ 等速傳遞）。另外，輸出用內齒輪130B中，透過螺栓孔 13 2B安裝未圖示的輸出軸，將與外齒輪120B之自轉相同的 旋轉輸出至外部。以後，分別將減速用內齒輪1 3 0 A、輸出 用內齒輪130B及內齒128A、128B統稱爲內齒輪130及內齒 128 ° 接著，以下對震盪體104、外齒輪120及內齒輪130之 關係進行說明。 如上所述，震盪體1 04之外周形狀由式（1 )〜式（3 )規定。在此，將內齒輪130之內齒128假想成圓筒形狀之 銷時，將從震盪體104之旋轉中心至咬合範圍中內齒128 ( 銷）之中心位置的距離R考慮爲內齒輪130之齒形之實體半 -12- 201207273 徑。外齒輪1 2 0之形狀能夠從式（1 )〜式（3 )分別由式 (5)〜式（7)求出的曲率半徑R1〜R3規定。 R 1 =R- L " (5) r2=R-l-厶 R ··· (6) R3=R-l-AR+ (L+AR*cos01)/cos62 …（7) 其中，外齒輪120的彎曲變形前的半徑設爲Rd時，相 對於外齒輪120之周長2nRd，距離AR、角度Θ1、Θ2、半徑 R及偏心量L各自的關係可以如式（8 )所示。 〔數學式1〕 2*^Rd = 2*^*(R-L) + 4* Ζ + Δ R*cos Θ1 cos Θ2 !一卟樣· ⑻ 式（8)可對半徑R進行如式（9)的變形。 〔數學式2〕 2*02 -- Θ2 ^-*cos02 )__n_ 勢 wd·.· (9: 在此，將通過偏心軸A和震盪體1 04之旋轉中心的直線 '和由外齒輪120 (之外齒124)和內齒輪130 (之內齒128 )之咬合產生的接觸點之共同法線之交點作爲基於外齒輪 120和內齒輪130的節距點。另外，規定外齒輪120的半徑 R 1之圓形的（具有與內齒輪1 3 0內咬合的剛性）假想的外 齒輪（稱爲假想外齒輪）1 20C中，設定減速比（稱爲假想 減速比）η。由此，如式（1〇)，由參數Gs (稱爲節距係 數）表示半徑R與從震盪體104之旋轉中心至基於外齒輪 -13- 201207273 120和減速用內齒輪130的節距點的距離（n+l)*L之比。藉 由導入節距係數Gs，能夠容易掌握外齒輪120和內齒輪130 各自的齒形之實體位置與節距點的相對位置關係並且能夠 容易進行這些參數彼此的調整。另外，節距係數Gs或假想 減速比η之値因外齒輪120A和減速用內齒輪130A、外齒輪 12 0Β和輸出用內齒輪130Β及該等的組合而不同。 〔數學式3〕 …（1 0) 由式（9 )和式（1 0 )能夠求出關於偏心量L的式（1 1 )° 〔數學式4〕 L = · Δ R *cos ΘΙ cos 02 cos62 2*02 •*cose2 …（1 1〉 在此，根據日本發明專利申請2009- 1 693 92號（未公 開）中提案的內容，藉由適當地選擇節距係數G s ’能夠增 大外齒輪120和內齒輪130之同時咬合數且提高耐棘輪性。 亦即，藉由利用外齒輪1 2 0之周長之關係’能夠增大 外齒輪120和內齒輪130之同時咬合數的同時，同理可決定 距離ΔΙΙ、角度Θ1、Θ2、半徑R及偏心量L。 另外，在本實施形態中’減速用內齒輪130A之內齒 • 14 - 201207273 128A之齒數（102)相對外齒輪120A之外齒124A之齒數（ 100 )多2個齒。亦即，設爲齒數差i = 2。由此，設想比減 速用內齒輪130A之齒數（102 )例如少4個齒（j = 4 ’ j>i ) 的假想外齒輪120C。因此，由於以角度Θ1規定的第1圓弧 部FΑ而彎曲變形的外齒輪120之齒形設定爲與第6圖所示的 假想外齒輪120C之齒形相等。 其次，主要利用第2圖對撓性咬合式齒輪裝置1〇〇之動 作進行說明。 若震盪體104透過未圖示的輸入軸之旋轉而旋轉’則 根據其旋轉狀態，外齒輪1 2 0 A通過震盪體軸承1 1 〇 A彎曲 變形。另外，此時，外齒輪120B亦透過震盪體軸承1 10B與 外齒輪120A以同相位彎曲變形。 外齒輪120之彎曲變形根據作爲震盪體104之外周形狀 之曲率半徑rl、r2、r3而完成。由於第3圖、第4圖所示的 震盪體104之第1圓弧部FA、第2圓弧部SA及第3圓弧部TA 中，曲率分別爲一定，所以於各圓弧部中的外齒輪120之 彎曲應力爲一定。由於第1圓弧部FA和第2圓弧部SA之連 接部份C及第2圓弧部SA和第3圓弧部TA之連接部份E中的 位置中，切線T 1、T2分別相同，所以防止連接部份中的急 劇的彎曲變形。同時，從震盪體1 04之旋轉中心至滾子 1 16A、1 16B (稱爲滾子1 16 )之距離的變化率成爲最小限 度。亦即，由於在連接部份C、E中，沒有滾子1 1 6的急劇 的軌道變動，所以滾子1 1 6之滑行小且扭矩之傳遞損耗少 -15- 201207273 震盪體104由外齒輪120彎曲變形，藉此外齒124於第1 圓弧部FA (咬合範圍）之部份中移動至半徑方向外側且咬 合於內齒輪1 3 0之內齒1 2 8。外齒1 2 4爲基於次擺線曲線的 形狀，內齒128之齒形爲相對外齒124成理論咬合之形狀。 因此，通過外齒124與內齒128之咬合，隨著咬合數的增大 ，即使負載扭矩大，耐棘輪性也高，並且能夠減少損耗而 實現扭矩傳遞效率。 當咬合時，對外齒124A施加與外齒124B不同的負荷（ 方向和大小）。但是，震盪體軸承110A、110B除了內圈 1 1 2以外，在軸向Ο上被分離爲相對於和減速用內齒輪 13 0A咬合的外齒124A的部份及相對於和輸出用內齒輪 130B咬合的外齒124B的部份。因此，分別防止由減速用內 齒輪130A與外齒124A之咬合所引起滾子116B之偏斜及由 輸出用內齒輪130B與外齒124B之咬合引起之滾子116A的 偏斜。 另外，由於滾子116爲圓柱形狀，因此比具備相同大 小滾珠的滾珠軸承耐負荷更大，且與內圈Π2及外圈118A 、Π 8B接觸的部份更多，所以能夠增大負載扭矩。 另外，外齒124在軸向Ο上被分割爲減速用內齒輪 130A所咬合的部份（外齒124A)和輸出用內齒輪130B所 咬合的部份（外齒1 2 4 B )。因此’當外齒輪1 2 0 A和減速用 內齒輪130A咬合時，假如在外齒124B上有變形等’也不會 因其變形在外齒124 A產生變形。同樣，當外齒輪120B和輸 出用內齒輪130B咬合時，假如在外齒124A有變形等’也不 -16- 201207273 會因其變形在外齒1 24B產生變形。亦即，藉由預先分割外 齒124，能夠通過一方的外齒124A(124B)之變形使另一 方的外齒124B ( 124A)變形，從而防止使其咬合關係惡化 之類的傳遞扭矩之降低。 外齒輪120A和減速用內齒輪130A之咬合位置隨著震 盪體104之長軸方向X之移動而旋轉移動。在此，若震盪體 104轉1圏，則外齒輪120A之旋轉相位僅延遲與減速用內齒 輪13 0A之齒數差。亦即，基於減速用內齒輪130A的減速 比能夠求出（（外齒輪12 0A之齒數-減速用內齒輪13 0A之齒 數）/外齒輪120A之齒數）。 由於外齒輪120B和輸出用內齒輪130B之齒數均相同， 所以外齒輪120B和輸出用內齒輪130B相互咬合的部份不會 移動，而是由相同的齒彼此相咬合。因此，從輸出用內齒 輪130B輸出與外齒輪120B之自轉相同的旋轉。其結果，能 夠從輸出用內齒輪130B取出根據基於減速用內齒輪130A的 減速比使震盪體104之旋轉的輸出減速。 在本實施形態中，震盪體1〇4之外周形狀爲將第1圓弧 部FA.、第2圓弧部SA及第3圓弧部TA依序連接在一起的形 狀。亦即，曲率半徑小於將內齒輪130和外齒輪120設爲咬 合狀態的第1圓弧部FA的第2圓弧部SA配置於第1圓弧部FA 與曲率半徑r3大於第1圓弧部FA的第3圓弧部TA之間。因 此，與從咬合狀態僅將第3圓弧部TA直接連接於第1圓弧部 FA時相比，能夠以更短的（旋轉）距離將內齒輪130、外 齒輪120設爲非咬合狀態。此時，（藉著自由決定距離ΔΙΙ -17- 201207273 )能夠任意決定第2圓弧部S A之曲率半徑r2。因此，能夠 從咬合狀態以短時間確實地確保短軸部（內齒輪1 3 〇和外 齒輪120未咬合的圓弧部或非咬合範圍）中的內齒輪13〇與 外齒輪120之間隙，且能夠自由地決定其間隙。亦即，與 以往技術相比，能夠更加確實地避免齒形之干涉。 同時，於本實施形態中，各圓弧部FA、SA、TA中的 外齒輪120的彎曲應力分別爲一定。並且，於第1圓弧部FA 、第2圓弧部SA及第3圓弧部ΤΑ的連接部份分別共用第1圓 弧部FA、第2圓弧部SA及第3圓弧部ΤΑ之切線ΤΙ、Τ2。因 此，防止震盪體104之連接部份C、Ε處的急劇的彎曲變形 。亦即，能夠盡可能抑制由外齒輪1 20之變形產生的彎曲 應力，且能夠提高傳遞扭矩。 並且，由於第2圓弧部SA亦由一定的曲率半徑r2規定 ，所以能夠簡化規定震盪體1 〇4的形狀的參數。因此能夠 有效地設計撓性咬合式齒輪裝置1 〇〇。 另外，在本實施形態中，震盪體1〇4與外齒輪120之間 配置具有多數個滾子116的震盪體軸承11〇。從震盪體1〇4 之旋轉中心至滾子116之距離之變化率成爲最小限度。亦 即，由於連接部份C、E處沒有滾子Π 6的急劇的軌跡變動 ，所以滾子1 1 6之滑行少且能夠以高效率進行外齒輪1 2 0之 彎曲，能夠謀求提高傳遞扭矩。 另外，在本實施形態中，將減速用內齒輪130A與外齒 輪120A之齒數差設爲i = 2時，設想與減速用內齒輪130A之 齒數差爲大於i( = 2)的j( = 4)且具有與減速用內齒輪130A內 -18- 201207273 咬合的剛性的假想外齒輪120C，通過第1圓弧部FA彎曲變 形的外齒輪1 2 0 A之齒形設定爲與假想外齒輪1 2 0 C之齒形相 同。因此，尤其能夠實現外齒輪120A與減速用內齒輪 1 3 0 A之理論咬合的同時，能夠容易地進行震盪體1 〇 4、外 齒輪120及內齒輪130之齒形設計。 亦即，根據本實施形態，盡可能抑制由外齒輪1 2 0之 變形產生的彎曲應力來避免由外齒輪120之變形產生的內 齒輪130與外齒輪120之齒形之干涉，從而實現負載扭矩之 增大。 雖針對本發明舉出第1實施形態進行了說明，但是， 本發明並非限定於第1實施形態。亦即，能夠在不脫離本 發明主旨的範圍內進行改良及設計之變更是不言而喻的。 例如，本實施形態中，外齒1 24雖是根據次擺線曲線 成型，但本發明並非限定於此。外齒可以是圓弧齒形，亦 可以利用其他齒形。並且，內齒能夠利用與外齒對應的齒 形。例如，如第7圖的第2實施形態，亦可以於基礎構件 222上配置圓筒形之銷，並將以作爲外齒224A、224B。此 時，外齒224A、224B爲可旋轉的圓弧齒形，與各自相對應 ，內齒成爲基於次擺線曲線的齒形。 另外，於上述實施形態中，雖是利用具有滾子的震盪 體軸承，但本發明並非限定於此，亦可僅以促進滑動的構 件而非轉動體配置於震盪體與外齒輪之間。 另外，於上述實施形態中，從輸出用內齒輪取出被減 速的輸出，但本發明並非限定於此。例如，亦可以是不利 -19 - 201207273 用輸出用內齒輪，而是利用所謂的杯形的彎曲變形的外胃 輪且從該外齒輪僅取出其自轉成份的撓性咬合式齒輪裝® 〇 另外，於第1實施形態中雖是將減速用內齒輪1 3 0 A之 內齒128A之齒數與外齒輪120A之外齒124A之齒數差i設定 爲2，但本發明中該齒數差i並非限定於2。例如，齒數差i 只要爲2以上的偶數，則可爲適當的數。另外，假想外齒 輪之齒數也只要少於外齒輪之外齒之實際齒數，則可爲適 當的數，且未必一定需要設想假想外齒輪。 另外，在上述實施形態中，構成震盪體1 04之外周的 第1曲線部、第2曲線部及第3曲線部分別爲圓弧形狀的第1 圓弧部FA、第2圓弧部SA及第3圓弧部TA，但是對於第2曲 線部及第3曲線部，並非限定於圓弧形狀。就第2曲線部而 言，只要爲曲率半徑小於第1曲線部的曲線形狀即可，且 就第3曲線部而言，只要爲大於第1曲線部的曲率半徑的曲 線形狀即可。另外，第3曲線部也可包括與第1曲線部相同 曲率半徑的部份。 (產業上之實用性） 本發明由於可避免內齒輪與外齒輪的齒形之干涉來實 現負載扭矩之增大，所以，與負載扭矩之大小無關，能夠 在需要減速機構的各種領域中應用。 【圖式簡單說明】 -20- 201207273 第1圖是表示本發明之第1實施形態之撓性咬合式齒輪 裝置之整體結構之一例的分解立體圖° 第2圖是表示該裝置之整體結構之一·例的剖視圖。 第3圖是表示該裝置之震盪體的圖。 第4圖是用於說明該裝置之震盪體之形狀的模式圖。 第5圖是組合該裝置之震盪體和震盪體軸承的槪略圖 〇 第6圖是該裝置之假想外齒輪和內齒輪的咬合槪念圖 〇 第7圖是表示本發明之第2實施形態之撓性咬合式齒輪 裝置的整體結構之一例之分解立體圖。 【主要元件符號說明】 100、200:撓性咬合式齒輪裝置 104 :震盪體 110、110A、110B、210、210A、210B:震盪體軸承 1 1 2 :內圈 1 1 4A，1 1 4B ：保持器 116、1 1 6A、1 1 6B ：滾子 1 1 8 A、1 1 8 B :夕f 圈 120、120A ' 1 20B ' 220、220A、220B:外齒輪 120C :假想外齒輪 122、222 :基礎構件 124、 124A、 124B、 224、 224A、 224B ：外齒 -21 - 201207273 128 ' 128A ' 128B ：內齒 1 30、1 30A、23 0、23 0A :減速用內齒輪（內齒輪） 130B、23 0B :輸出用內齒輪 132A、132B:螺拴孔 〇 :軸向 X:震盪體之長軸方向 Y:震盪體之短軸方向 FA :第1圓弧部（第1曲線部） S A :第2圓弧部（第2曲線部） TA :第3圓弧部（第3曲線部） r:震盪體之長軸半徑 rl :震盪體的第1圓弧部之曲率半徑 r2:震盪體的第2圓弧部之曲率半徑 r3:震盪體的第3圓弧部之曲率半徑 -22-201207273 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a flexible snap-in gear device. [Prior Art] The flexible snap-in gear device of Patent Document 1 includes: an internal gear having rigidity; an external gear having flexibility capable of being internally engaged with the internal gear; and an oscillating body by causing the external gear to The outer circumference is bent and deformed to realize the inner engagement of the inner gear and the outer gear. Further, in Patent Document 1, the outer peripheral shape of the vibrating body in which the external gear is bent and deformed is a shape in which arcs of two different curvature radii are connected. In addition, in the concussion body, the tangent is shared by the connecting portions of the two arcs. Therefore, in Patent Document 1, the variation in the radius of curvature of the external gear can be minimized and the bending stress of the external gear can be prevented from increasing, and the transmission torque can be improved. [Patent Document 1] Japanese Laid-Open Patent Publication No. 2009-299765 (Problem to be Solved by the Invention) In Patent Document 1, "focusing on the tooth shape and the short-axis portion of the external gear (the internal gear and the external gear are not The stress of the external gear in the occluded arc portion determines the connecting portion of the two arcs in the oscillating body. Here, the short-axis portion is determined by the occlusion angle Θ of the range in which the internal gear and the external gear are engaged, and the eccentric amount L of the oscillating body (outer gear). However, for example, when the angle θ is small and the amount of eccentricity is 1 hour, in Patent Document 1, there is also a risk that the short shaft portion generates a tooth shape interference of the internal gear and the -5 - 201207273 external gear. In other words, it is difficult to find out the three parameters of the angle Θ and the eccentricity L, which are difficult to overcome the tooth shape of the external gear, the stress of the external gear in the short shaft portion, and the tooth shape of the internal gear and the external gear. Best choice. In addition, even in the state of geometrically non-toothed interference, there is a possibility that tooth-shaped interference occurs at an unexpected position (in the short-axis portion) due to deformation of the external gear based on the load torque. Therefore, it is preferable to ensure the non-engagement range of the internal gear and the external gear so that the gap between the internal gear and the external gear in the short shaft portion is as large as possible. In addition, in order to avoid interference of the upper tooth profile, it is also possible to consider cutting the tooth tip of the internal gear. However, at this time, there is a problem that the number of occlusions of the internal gear and the external gear is reduced. Accordingly, the present invention has been made to solve the above problems, and an object of the invention is to provide a tooth shape which avoids bending stress caused by deformation of an external gear as much as possible to avoid internal gears and external gears caused by deformation of an external gear. A flexible snap-in gear device that interferes to achieve an increase in load torque. (Means for Solving the Problems) The present invention solves the above-described problems, and a flexible snap-in gear device includes: an internal gear having rigidity; and an external gear having flexibility capable of being internally engaged with the internal gear; The oscillating body is configured to engage the inner gear and the outer gear by bending and deforming the outer gear on the outer circumference thereof, wherein the outer peripheral shape of the oscillating body is sequentially connected to set the inner gear and the outer gear to a nip state. And the first curved portion having an arc shape, the second curved portion having a curvature of less than 201207273, and the second curved portion having a smaller radius of curvature than the first curved portion and the non-engaged state of the internal gear and the external gear. The shape of the third curved portion, and the tangent of the first curved portion, the second curved portion, and the third curved portion are shared by the first curved portion, the second curved portion, and the third curved portion. . In the present invention, the three curved portions constitute the oscillating body, and the number of parameters determining the short-axis portion is increased to avoid the interference of the tooth shape. In the present invention, the outer peripheral shape of the oscillating body is specifically formed into a shape in which the first curved portion, the second curved portion, and the third curved portion of the circular arc shape are sequentially connected. In other words, the second curved portion having the radius of curvature smaller than the first curved portion in which the internal gear and the external gear are in the engaged state is disposed between the first curved portion and the third curved portion having the curvature radius larger than the first curved portion. Therefore, the internal gear and the external gear can be brought into a non-engaged state from the engaged state by a shorter (rotation) distance than when the third curved portion is directly connected to the first curved portion. In this case, the radius of curvature of the second curved portion can be arbitrarily determined. That is, the interference of the tooth profile can be further reliably avoided as compared with the prior art. Meanwhile, in the present invention, since the radius of curvature of each curved portion is limited to each curved portion, the bending stress of the external gear in each curved portion is reduced. Further, since the connecting portions of the first curved portion, the second curved portion, and the third curved portion share the tangent of the first curved portion, the second curved portion, and the third curved portion, the connecting portion of the shocking body is prevented. A sharp bending deformation. That is, it is possible to suppress the bending stress caused by the deformation of the external gear as much as possible, and to increase the transmission torque. Further, if the second curved portion is defined by a constant radius of curvature, the parameter of the shape of the vibrating body can be specified by 201207273. Therefore, the flexible snap-in gear device can be effectively designed. According to the present invention, the bending stress caused by the deformation of the external gear is suppressed as much as possible to avoid the interference of the tooth shapes of the internal gear and the external gear caused by the deformation of the external gear, thereby achieving an increase in the load torque. [Embodiment] Hereinafter, an example of a first embodiment of the present invention will be described in detail with reference to the drawings. First, the overall configuration of this embodiment will be briefly described using Figs. 1 to 4 . The flexible snap gear device 100 includes a rigid internal gear (internal gear) 13 0A having a rigidity, and an external gear 120A having flexibility for being internally engaged with the internal gear 1300 for deceleration; and the oscillating body 104 The inner gear of the deceleration internal gear i30A and the outer gear 120A are engaged by bending and deforming the outer gear 120A on its outer circumference. Here, as shown in FIG. 4, the outer peripheral shape (the outer peripheral shape in the cross section orthogonal to the axial direction 震) of the oscillating body 104 is an arc portion having three different radii of curvature rl, r2, and r3 (first The circular arc portion FA and the second circular arc portion SA' third circular arc portion TA) are sequentially connected to each other. Further, the tangent lines T2 and T2 in the connection portions C and E of the respective arc portions (the first arc portion FA, the second arc portion SA, and the third arc portion TA) are shared. Hereinafter, each constituent element will be described in detail. As shown in Fig. 3 (A) and (B), the oscillating body 104 has a columnar shape, and an input shaft hole 106 into which an input shaft (not shown) is inserted is formed at the center. When the input shaft -8 - 201207273 is inserted and rotated, a keyway is provided in the input shaft hole 106'! 〇 8' so that the oscillating body 104 rotates integrally with the input shaft. Here, as shown in Fig. 3(A), when the center of rotation of the oscillating body 104 is located at the center of the XY coordinate, the oscillating body 104 has an axisymmetric shape formed on both the X-axis and the Y-axis. Therefore, the shape of the first quadrant of the vibrating body 104 will be described below using Fig. 4 . As shown in Fig. 4, the outer peripheral shape of the vibrating body 104 is a shape in which three arc portions (the first arc portion FA, the second arc portion SA, and the third arc portion TA) are connected together (three Arc shape). The first circular arc portion FA (first curved portion) is an arc having a radius of curvature r 1 centered on a point A (referred to as an eccentric axis), and constitutes an external gear 1 2 0 A and a reduction internal gear 1 3 0 A The arc portion (also called the nip range) that is in the engaged state. The second arc portion SA (second curve portion) is an arc having a radius of curvature r2 around the point D of the distance ΔΙΙ from the point A, and constitutes the non-engaged state of the external gear 120A and the reduction internal gear 130A. One part of the arc portion (also known as the non-engagement range). The distance ΔΙΙ is finally a variable for determining the gap between the external gear 120A and the internal gear 130A for deceleration in the non-engagement range (short shaft portion). The third arc portion TA (third curve portion) is an arc having a radius of curvature r3 around the point F, and constitutes an arc in which the external gear 1 20 A and the reduction internal gear 1 3 0 A are in a non-engaged state. Department (other range of non-occlusion range). The length of the first circular arc portion FA is determined by the angle formed by the long axis direction X and the tangent normal at the point c, that is, the engagement angle e丨. The length of the second circular arc portion SA is determined by subtracting the angle of the occlusion angle Θ1 from the angle Θ2 between the long axis direction X and the tangent normal at the point E (Θ2>Θ1). Therefore, the coordinates of 'point A' D and F are L-centered, and in Fig. 4, they become 201207273 (L, Ο), (L + AR * co s θ 1, Δ R * si η θ 1 ), (0, - (L + AR * cosei) * tane2 + ^ R * sin01 That is, if in the long axis direction X, from the center of rotation of the oscillating body 104 (in the nip range) to the point B on the outer circumference of the oscillating body 104 The distance r (the major axis radius of the oscillating body 104) is as shown in Fig. 4, and the curvature radius rl of the first circular arc portion FA is expressed by the formula (1). r 1 = r — L ··· (1) Further, as shown in Fig. 4, the curvature radius r2 of the second circular arc portion SA is expressed by the formula (2). r 2 = r 1 - Δ R = r - L - 厶R · (2) In addition, The tangent line T 1 is shared by the connecting portion C of the first circular arc portion FA and the second circular arc portion SA. Further, as shown in Fig. 4, the connecting portion between the second circular arc portion SA and the third circular arc portion TA The tangential line T2 is also shared by the portion E. Further, the radius of curvature r3 of the third circular arc portion TA is (curvature radius r2 + length DF)', so the radius of curvature r3 is represented by the formula (3). r3 = r - L - 厶 R + ( L + AR*cos61) /cos02 (3) where, since the angle Θ2 is larger than the angle Θ1 ', the equation (4) R2 < rl < r3 · (4) As shown in Fig. 2, the oscillating body bearing 1 10A is a bearing disposed between the outer side of the oscillating body 104 and the inner side of the external gear 1 2 0 A. As shown in Fig. 5, the earthquake body bearing includes an inner ring 112, a retainer 114A, a roller 116A as a rotating body, and an outer ring 118A. The inner side of the inner ring 112 abuts against the vibrating body 104, and the inner ring 112 and the vibrating body 104 - Rotating while the body is deformed. -10- 201207273 Roller 1 1 6 A is cylindrical (including needle roller). Therefore, compared with when the rotating body is a ball, 'Because the roller 116A and the inner ring 112 The contact portion of the outer casing 118A is increased, so that the load capacity can be increased. That is, the transmission torque of the oscillating body bearing 11〇a can be increased by the use of the roller 116A' and the life can be extended. 1 8 A is disposed on the outer side of the roller 1 1 6 A. The outer ring 1 1 8 A is bent and deformed by the rotation of the oscillating body 104, and the external gear 120A disposed outside thereof is deformed. Further, as shown in Fig. 2, The slewing body bearing 110B is the same as the oscillating body bearing 110A, and includes an inner ring 112, a retainer 114B, a roller 116B, and an outer ring 118B. 112 is common to the oscillating body bearings 110A, 110B, and the 'holder 1MB, the roller 116B, and the outer ring 118B are disposed in the axial direction of the holder 114A, the roller 1 16A, and the outer ring 1 18A, respectively. And the same shape. Hereinafter, the oscillating body bearings 110A, 110B are collectively referred to as a oscillating body bearing 1 1 0. As shown in Figs. 1 and 2, the external gear 120A is engaged with the internal gear 130A for deceleration. The outer gear 120A includes a base member 122 and outer teeth 124A. The base member 1 22 is a flexible tubular member disposed on the outer side of the oscillating body bearing 1 10A and integrally formed with the outer teeth 124A. The outer teeth 124A are formed according to a trochoidal curve. As shown in Fig. 1 and Fig. 2, the external gear 120B is engaged with the inner gear 130B for output. Further, the external gear 120B is the same as the external gear 120A, and includes a base member 122 and external teeth 124B. The outer teeth 124B and the outer teeth 124A are of the same number and are formed into the same shape. Here, as shown in Fig. 1, the external teeth 1 2 4 A and the external teeth 1 2 4 B are divided in the axial direction 0, but the base members -11 - 201207273 122 are common. Therefore, the eccentric amount L of the oscillating body 104 is transmitted to the outer teeth 1 24 A and the outer teeth 1 2 4 B in the same phase. Thereafter, the external gears 1 2 0 A, 1 2 0 B and the external teeth 124A, 124B are collectively referred to as an external gear 120 and external teeth 124, respectively. The internal gear for deceleration 1 3 〇 A is formed of a member having rigidity. The decelerating internal gear 130A has a number of teeth of only i (i = 2, 4, ...) pieces of teeth smaller than the teeth 124A of the external gear 120A. In the reduction internal gear 130A, an outer casing (not shown) is fixed through the bolt hole 132A. Further, the reduction internal gear 130A contributes to the deceleration of the rotation of the oscillation body 104 by engaging with the external gear 120A. The internal gear 128A of the internal gear 130A is formed to be theoretically engaged with the external teeth 124A based on the trochoidal curve. On the other hand, the output internal gear 130B is also formed of a member having rigidity similar to the internal gear 130A for reduction. The output internal gear 1 30B has the number of teeth (equal speed transmission) of the internal teeth 128B having the same number of teeth as the teeth 124B outside the external gear 120B. Further, in the output internal gear 130B, an output shaft (not shown) is attached through the bolt hole 13 2B, and the same rotation as that of the external gear 120B is outputted to the outside. Thereafter, the internal gear 1 3 0 A for reduction, the internal gear 130B for output, and the internal teeth 128A and 128B are collectively referred to as an internal gear 130 and an internal tooth 128°, respectively. Next, the following applies to the oscillation body 104, the external gear 120, and the internal gear 130. The relationship is explained. As described above, the outer peripheral shape of the oscillating body 104 is defined by the formulas (1) to (3). Here, when the inner teeth 128 of the internal gear 130 are assumed to be cylindrically shaped pins, the distance R from the center of rotation of the oscillating body 104 to the center position of the internal teeth 128 (pin) in the nip range is considered as the internal gear 130. The solid shape of the tooth is half-12- 201207273. The shape of the external gear 1 220 can be defined by the curvature radii R1 to R3 obtained by the equations (5) to (7), respectively, from the equations (5) to (7). R 1 =R- L " (5) r2=Rl-厶R ··· (6) R3=Rl-AR+ (L+AR*cos01)/cos62 (7) where the external gear 120 is bent before deformation When the radius is set to Rd, the relationship between the distance AR, the angle Θ1, the Θ2, the radius R, and the eccentric amount L with respect to the circumference 2nRd of the external gear 120 can be expressed by the formula (8). [Math 1] 2*^Rd = 2*^*(RL) + 4* Ζ + Δ R*cos Θ1 cos Θ2 ! A sample (8) Equation (8) can perform radius R as in equation (9) Deformation. [Math 2] 2*02 -- Θ 2 ^-*cos02 )__n_ Potential wd··· (9: Here, a straight line passing through the center of rotation of the eccentric axis A and the oscillating body 104) and by the external gear 120 ( The intersection of the common normals of the contact points generated by the engagement of the external teeth 124) and the internal gears 130 (the internal teeth 128) is taken as the pitch point based on the external gear 120 and the internal gear 130. In addition, the radius R of the external gear 120 is specified. In a circular external gear (having a rigidity that engages with the internal gear 130), a virtual reduction gear (referred to as a virtual external gear) 1 20C sets a reduction ratio (referred to as a virtual reduction ratio) η. (1〇), the distance G from the center of rotation of the oscillating body 104 to the pitch point based on the external gear-13-201207273 120 and the internal gear 130 for deceleration is represented by the parameter Gs (referred to as the pitch coefficient) (n+) l) Ratio of * L. By introducing the pitch coefficient Gs, the relative positional relationship between the physical position of each tooth shape of the external gear 120 and the internal gear 130 and the pitch point can be easily grasped and adjustment of these parameters can be easily performed. In addition, the pitch coefficient Gs or the virtual reduction ratio η is caused by the external gear 120A and the internal gear 130A for deceleration, The gear 120 Β and the output internal gear 130 Β are different from each other. [Math 3] (1 0) From the equations (9) and (10), the equation about the eccentric amount L can be obtained (1 1 ° ° [Math 4] L = · Δ R *cos ΘΙ cos 02 cos62 2*02 •*cose2 (1 1> Here, according to the proposal in Japanese Patent Application No. 2009-1 693 92 (unpublished) By appropriately selecting the pitch coefficient G s ', the number of simultaneous engagement of the external gear 120 and the internal gear 130 can be increased and the ratchet resistance can be improved. That is, by using the relationship of the circumference of the external gear 1 2 0 While the number of meshing of the external gear 120 and the internal gear 130 is the same, the distance ΔΙΙ, the angle Θ1, the Θ2, the radius R, and the eccentric amount L can be determined. In addition, in the present embodiment, the internal gear of the internal gear 130A for deceleration is used. • The number of teeth (102) of 14 - 201207273 128A is two more than the number of teeth (100) of the teeth 124A outside the external gear 120A. That is, the difference in the number of teeth is i = 2. Therefore, it is assumed that the gear is smaller than the internal gear 130A for deceleration. The number of teeth (102) is, for example, an imaginary external gear 120C having 4 teeth (j = 4 ' j > i ). The tooth profile of the external gear 120 that is bent and deformed by the first circular arc portion FΑ defined by the angle Θ1 is set to be equal to the tooth profile of the virtual external gear 120C shown in Fig. 6. Next, the second embodiment is mainly used for the flexible occlusion. The operation of the gear unit 1 will be described. When the vibrating body 104 is rotated by the rotation of the input shaft (not shown), the external gear 1 2 0 A is bent and deformed by the vibrating body bearing 1 1 〇A according to the rotation state. Further, at this time, the external gear 120B is also bent and deformed in the same phase by the oscillating body bearing 1 10B and the external gear 120A. The bending deformation of the outer gear 120 is performed in accordance with the radius of curvature rl, r2, r3 which is the outer peripheral shape of the vibrating body 104. Since the curvatures of the first circular arc portion FA, the second circular arc portion SA, and the third circular arc portion TA of the vibrating body 104 shown in FIGS. 3 and 4 are constant, the arc portions are fixed. The bending stress of the outer gear 120 is constant. The tangent lines T 1 and T 2 are the same in the position of the connecting portion C between the first circular arc portion FA and the second circular arc portion SA and the connecting portion E between the second circular arc portion SA and the third circular arc portion TA. , so as to prevent sharp bending deformation in the joint portion. At the same time, the rate of change from the center of rotation of the oscillating body 104 to the rollers 1 16A, 1 16B (referred to as the roller 1 16 ) is minimized. That is, since there is no sharp orbital variation of the roller 1 16 in the connecting portions C and E, the sliding of the roller 1 16 is small and the transmission loss of the torque is small -15-201207273 The oscillating body 104 is composed of an external gear The bending deformation of 120 causes the outer teeth 124 to move to the outer side in the radial direction in the portion of the first arc portion FA (the nip range) and to engage the inner teeth 1 28 of the inner gear 130. The outer teeth 1 24 are shaped based on a trochoidal curve, and the teeth of the inner teeth 128 are in a shape that is theoretically engaged with the outer teeth 124. Therefore, by the engagement of the external teeth 124 and the internal teeth 128, as the number of occlusions increases, even if the load torque is large, the ratchet resistance is high, and the loss can be reduced to achieve the torque transmission efficiency. When engaged, the external teeth 124A exert a different load (direction and size) than the external teeth 124B. However, the slewing body bearings 110A and 110B are separated from the inner ring 112 in the axial direction, and are separated from the outer teeth 124A that are engaged with the reduction internal gear 130A and the outer gears 130B. The portion of the external tooth 124B that is engaged. Therefore, the deflection of the roller 116B caused by the engagement of the decelerating internal gear 130A and the external teeth 124A and the deflection of the roller 116A caused by the engagement of the output internal gear 130B and the external teeth 124B are prevented, respectively. Further, since the roller 116 has a cylindrical shape, it is more resistant to load than a ball bearing having the same small ball, and has more contact with the inner ring Π2 and the outer ring 118A, Π 8B, so that the load torque can be increased. Further, the external teeth 124 are divided into a portion where the decelerating internal gear 130A is engaged (the external teeth 124A) and a portion where the output internal gear 130B is engaged (the external teeth 1 2 4 B ). Therefore, when the external gear 1 2 0 A and the reduction internal gear 130A are engaged, if there is deformation or the like on the external teeth 124B, deformation of the external teeth 124 A is not caused by the deformation. Similarly, when the external gear 120B and the output internal gear 130B are engaged, if the external teeth 124A are deformed or the like, the deformation of the external teeth 1 24B is caused by the deformation thereof. In other words, by dividing the external teeth 124 in advance, the other external teeth 124B (124A) can be deformed by deformation of one of the external teeth 124A (124B), thereby preventing a decrease in the transmission torque such as deterioration of the engagement relationship. The meshing position of the outer gear 120A and the reduction internal gear 130A is rotationally moved in accordance with the movement of the long axis direction X of the vibrating body 104. Here, when the vibrating body 104 is rotated by one turn, the rotational phase of the external gear 120A is delayed only by the difference in the number of teeth from the decelerating internal gear 130A. In other words, the reduction ratio of the internal gear 130A for deceleration can be obtained ((the number of teeth of the external gear 120A - the number of teeth of the internal gear 13 0A for deceleration) / the number of teeth of the external gear 120A). Since the number of teeth of the external gear 120B and the output internal gear 130B are the same, the portions where the external gear 120B and the output internal gear 130B are engaged with each other do not move, but the same teeth are engaged with each other. Therefore, the same rotation as the rotation of the external gear 120B is output from the output internal gear 130B. As a result, the output of the rotation of the oscillating body 104 can be decelerated from the output internal gear 130B by the reduction ratio based on the internal gear 130A for deceleration. In the present embodiment, the outer peripheral shape of the oscillating body 1〇4 is a shape in which the first circular arc portion FA., the second circular arc portion SA, and the third circular arc portion TA are sequentially connected to each other. In other words, the second circular arc portion SA having the radius of curvature smaller than the first circular arc portion FA in which the internal gear 130 and the external gear 120 are in the engaged state is disposed on the first circular arc portion FA and the curvature radius r3 is larger than the first circular arc portion. Between the third arc portion TA of the FA. Therefore, the internal gear 130 and the external gear 120 can be brought into a non-engaged state at a shorter (rotational) distance than when the third circular arc portion TA is directly connected to the first circular arc portion FA from the engaged state. At this time, the radius of curvature r2 of the second arc portion S A can be arbitrarily determined (by the freedom determination distance ΔΙΙ -17 - 201207273). Therefore, it is possible to surely secure the gap between the internal gear 13A and the external gear 120 in the short-axis portion (the arc portion or the non-engagement range in which the internal gear 13 and the external gear 120 are not engaged) in a short time from the engaged state, and The gap can be freely determined. That is, it is possible to more reliably avoid the interference of the tooth shape as compared with the prior art. Meanwhile, in the present embodiment, the bending stress of the external gear 120 in each of the circular arc portions FA, SA, and TA is constant. Further, the first arc portion FA, the second arc portion SA, and the third arc portion are shared by the connecting portions of the first arc portion FA, the second arc portion SA, and the third arc portion 分别, respectively. Tangent Τ, Τ 2. Therefore, the sharp bending deformation of the connecting portion C and the weir of the vibrating body 104 is prevented. That is, the bending stress generated by the deformation of the external gear 120 can be suppressed as much as possible, and the transmission torque can be improved. Further, since the second circular arc portion SA is also defined by a constant radius of curvature r2, the parameters defining the shape of the oscillating body 1 〇4 can be simplified. Therefore, the flexible snap gear device 1 can be effectively designed. Further, in the present embodiment, the oscillating body bearing 11A having a plurality of rollers 116 is disposed between the oscillating body 1〇4 and the external gear 120. The rate of change from the center of rotation of the oscillating body 1〇4 to the distance of the roller 116 is minimized. In other words, since there is no sharp trajectory change of the roller Π 6 at the connection portions C and E, the roller 1 16 has less slid and the external gear 1 2 0 can be bent with high efficiency, and the transmission torque can be improved. . In the present embodiment, when the difference in the number of teeth between the internal gear 130A for deceleration and the external gear 120A is i = 2, it is assumed that the difference in the number of teeth from the internal gear 130A for deceleration is greater than i (= 2) j (= 4) The imaginary external gear 120C having a rigidity that is engaged with the inner gear of the reduction internal gear 130A -18-201207273, the tooth profile of the external gear 1 2 0 A that is bent and deformed by the first circular arc portion FA is set to be the imaginary external gear 1 2 0 C has the same tooth shape. Therefore, in particular, the toothed design of the oscillating body 1 〇 4, the external gear 120, and the internal gear 130 can be easily performed while the outer gear 120A and the internal gear for deceleration 1 3 0 A are engaged. That is, according to the present embodiment, the bending stress generated by the deformation of the external gear 1 20 is suppressed as much as possible to avoid the interference of the tooth shape of the internal gear 130 and the external gear 120 caused by the deformation of the external gear 120, thereby realizing the load torque. Increased. Although the first embodiment has been described with respect to the present invention, the present invention is not limited to the first embodiment. That is, it is needless to say that modifications and design changes can be made without departing from the spirit of the invention. For example, in the present embodiment, the external teeth 1 24 are formed according to a trochoidal curve, but the present invention is not limited thereto. The external teeth may be arcuate or other tooth shapes. Also, the internal teeth can utilize a tooth shape corresponding to the external teeth. For example, as in the second embodiment of Fig. 7, a cylindrical pin may be disposed on the base member 222 as the external teeth 224A and 224B. At this time, the external teeth 224A, 224B are rotatable arc-shaped teeth, corresponding to each, and the internal teeth become a tooth shape based on the trochoidal curve. Further, in the above embodiment, the oscillating body bearing having the roller is used. However, the present invention is not limited thereto, and the slidable member may be disposed between the oscillating body and the external gear only by the member that promotes sliding. Further, in the above embodiment, the decelerated output is taken out from the output internal gear, but the present invention is not limited thereto. For example, it is also possible to use the internal gear for the output of the -19 - 201207273, but to use the so-called cup-shaped curved deformed outer stomach wheel and to extract only the self-rotating component of the flexible bite gear from the external gear. In the first embodiment, the number of teeth i of the internal teeth 128A of the internal gear for deceleration 1 3 0 A and the tooth difference i of the external teeth 124A of the external gear 120A are set to 2, but the difference in the number i of the teeth is not limited in the present invention. At 2. For example, the difference in the number of teeth i may be an appropriate number as long as it is an even number of 2 or more. Further, the number of teeth of the imaginary external gear wheel may be an appropriate number as long as it is smaller than the actual number of teeth of the external gear, and it is not always necessary to envisage a virtual external gear. Further, in the above-described embodiment, the first curved portion, the second curved portion, and the third curved portion that constitute the outer periphery of the oscillating body 104 are the first circular arc portion FA and the second circular arc portion SA of the circular arc shape, respectively. The third arc portion TA is not limited to the circular arc shape for the second curved portion and the third curved portion. The second curved portion may be a curved shape having a radius of curvature smaller than that of the first curved portion, and the third curved portion may be a curved shape larger than the radius of curvature of the first curved portion. Further, the third curved portion may include a portion having the same radius of curvature as the first curved portion. (Industrial Applicability) The present invention can achieve an increase in load torque by avoiding interference between the internal gear and the external gear tooth shape, and therefore can be applied to various fields requiring a speed reduction mechanism regardless of the magnitude of the load torque. [Brief Description of the Drawings] -20-201207273 Fig. 1 is an exploded perspective view showing an example of the overall configuration of the flexible snap gear device according to the first embodiment of the present invention. FIG. 2 is a view showing one of the overall structures of the device. · A cross-sectional view of an example. Fig. 3 is a view showing a vibrating body of the apparatus. Fig. 4 is a schematic view for explaining the shape of a vibrating body of the apparatus. Fig. 5 is a schematic view showing a combination of a vibrating body and a vibrating body bearing of the apparatus. Fig. 6 is a view showing a occlusion of a virtual external gear and an internal gear of the apparatus. Fig. 7 is a view showing a second embodiment of the present invention. An exploded perspective view of an example of the overall structure of the flexible snap gear device. [Description of main component symbols] 100, 200: flexible snap-in gear device 104: oscillating body 110, 110A, 110B, 210, 210A, 210B: oscillating body bearing 1 1 2: inner ring 1 1 4A, 1 1 4B: keep 116, 1 1 6A, 1 1 6B: roller 1 1 8 A, 1 1 8 B : evening f circle 120, 120A ' 1 20B ' 220, 220A, 220B: external gear 120C: imaginary external gear 122, 222: Base member 124, 124A, 124B, 224, 224A, 224B: external tooth-21 - 201207273 128 '128A ' 128B: internal tooth 1 30, 1 30A, 23 0, 23 0A : internal gear for reduction (internal gear) 130B, 23 0B : Output internal gears 132A and 132B: threaded bore 〇: axial direction X: long axis direction of the oscillating body Y: short axis direction of the oscillating body FA: first circular arc portion (first curved portion) SA : 2 arc portion (second curve portion) TA: third arc portion (third curve portion) r: long axis radius of the oscillation body rl: radius of curvature of the first arc portion of the oscillation body r2: the first part of the oscillation body 2 radius of curvature of the arc portion r3: radius of curvature of the third arc portion of the vibrating body -22-