201014991 六、發明說明： 【發明所屬之技術領域】 本申請主張基於2008年10月9日申請之日本專利申 請第2008-2 623 93號之優先權。該申請之全部內容藉由參 照援用在該說明書中。 本發明是關於減速裝置及減速裝置向對象機械之安裝 構造。 【先前技術】 於專利文獻1中，公開有將減速裝置之中空之輸出軸 直接嵌入到對象機械之被驅動軸之構造。在該文獻中，對 於該被驅動軸和輸出軸之連結，提出利用不具有間隙之摩 擦緊固連結之方法和利用由鍵之形狀性卡合之方法》 專利文獻1:日本特開2001-99177號公報 但是，由摩擦締結來連結上述被驅動軸和輸出軸之方 I 法，不僅在減速裝置之安裝時，在安裝後也需要始終適當 地管理固定轉矩。因此，具有減速裝置向對象機械之安裝 及其維持管理麻煩之問題。 另一方面，利用由鍵之形狀性之卡合而連結被驅動軸 和輸出軸之方法，由於殘留由軸和軸之尺寸差所引起之微 小間隙、及形狀性之卡合部之微小間隙，所以有不可避免 地容易產生磨損之問題。這是因爲，需要一面握持住重的 減速裝置同時對準被驅動軸和該輸出軸之軸心而將該減速 裝置嵌入到被驅動軸’需要在輸出軸之內徑和被驅動軸之 -5- 201014991 外徑之間確保適合之“尺寸差”。確保嵌入之容易性和防 止磨損是處於權衡取捨之係。若優先考量嵌入之容易性而 較大地設定尺寸差，則更容易產生磨損。若較小地設定尺 寸差，則雖難以產生磨損，但是嵌入作業會變得極其困難 【發明內容】 本發明是爲了消除以往之問題而硏創的，其課題在於 @ ，有效地防止磨損之產生，並且一倂簡化減速裝置向對象 機械之被驅動軸進行嵌入或運轉時之維護。 本發明是驅動對象機械之被驅動軸的減速裝置，具備 中空之輸出軸，該輸出軸可被上述對象機械之被驅動軸插 入，並與該被驅動軸具有間隙而結合爲可傳遞動力；從該 輸出軸之端部沿著該輸出軸，在該輸出軸之內周和上述被 驅動軸之外周之間，確保有可保持潤滑油之空間部，藉此 解決上述課題。 癰 於本發明中，由於在中空之輸出軸之內周和對象機械 之外周之間確保有可保持潤滑油之空間部，所以空氣不能 侵入到比該空間部更靠軸方向內側。因此，即使是被驅動 軸和輸出軸具有間隙而結合爲可傳遞動力之構造，也可以 持續長期確實地防止磨損之產生。 此外，該空間部，由於是形成在輸出軸之端部附近， 所以藉由該空間部之存在，使得在輸出軸之端部之對象機 械之外周直徑和在輸出軸之端面之內周直徑之差增大。因 -6- 201014991 • 此，減速裝置向對象機械之裝配極其容易。因此，在比空 間部靠軸方向內側處，可以無阻礙地反而比過去縮小尺寸 差，而更加難以產生磨損，並且也沒有產生噪音動作或擺 震動作等之憂慮。 而且，在本發明中，根據發明之宗旨，僅實施所謂 「倒角」處理者，並不被包含在本發明之「空間部」之槪 念。通常，進行倒角時之半徑R是小於軸之內徑（直徑） φ 之5%之半徑。例如，輸出軸之中空部之內徑（直徑）爲 15mm〜55mm時，倒角半徑是0.5mm〜2.5mm左右，即使 再大也是不到5%。因此，該範圍之倒角與本發明之「空 間部」之技術性意義不同。 發明之效果 根據本發明，能有效地防止磨損之產生，並且可簡化 減速裝置向對象機械之被驅動軸之嵌入或維護。 【實施方式】 以下，參照附圖對本發明之實施方式之一例詳細地進 行說明。 圖1是表示應用本發明之實施方式之一例之齒輪電動 機（減速裝置）之局部槪略俯視剖面圖。圖2是其箭頭所 示Π部分之放大剖面圖。 該齒輪電動機GM1主要由電動機16和減速機18所 構成。電動機16具備電動機外殻20，減速機18具備減 201014991 速機外殻22。減速機外殻22旋轉自如地支承有中空之輸 出軸24。 輸出軸24具備可被輸送機（對象機械：圖示省略） 等之被驅動軸28插入之貫通孔2 4h。輸出軸24和被驅動 軸28之間之動力傳遞是夾介鍵32而“形狀性之卡合” ’ 即，藉由具有間隙而結合爲可傳遞動力之構造來進行。而 且，取代由鍵32之形狀性之卡合，例如也可以設爲花鍵 等之形狀性之卡合。在本發明中，對於齒輪電動機GM1 ❿ 之具體性之電動機16之構成、或者減速機18之減速機構 等之構成並無特別限定。 如詳細地示於圖2，在輸出軸24之內周24A和對象 機械之被驅動軸28之外周28A之間’確保有可保持潤滑 油G1之空間部SP1。在此實施方式中，空間部SP1之軸 方向X之長度Lsl是設定爲輸出軸24之貫通孔24h之（ 空間部P S1以外的）半徑Hr 1之1 /2左右。例如，若是內 徑（Hrlex2)爲15mm之軸，則爲3〜5mm左右，若是內 參 徑（Hrlex2 )爲55mm之軸，則爲5〜10mm左右。這是 因爲考慮到：即使潤滑油G1多少發生乾燥，也可一面確 實地防止空氣侵入到比該空間部SP1更靠近軸方向內側， 同時一面防止磨損；明顯大於上述之通常之倒角R、相對 ^ 於該尺寸之內徑之軸之半〇.5mm〜2.5mm。 空間部SP1，其形狀是被設定爲：沿著輸出軸24之 軸方向X越朝向該輸出軸24之端部24B，該空間部SP1 之半徑方向R之高度SPhl越增大。其結果，在輸出軸24 -8- 201014991 • 之端面24C部分之該輸出軸24之貫通孔24h的半徑Hrle ，是比貫通孔24h之空間部SP1以外之部分的半徑Hrl還 大一△ 1 (若以直徑考慮則爲△ 1的2倍量）。例如，內 徑（Hrlex2)爲 15mm 〜55mm 時，Δ1 爲 1.5mm 〜5_5mm 左右（內徑的10%左右）。這也明顯大於倒角半徑R之 0 · 5mm〜2.5mm (內徑的5 %左右）。藉此，在效果上可取 得：將軸方向中央部附近之輸出軸24和對象機械之被驅 Φ 動軸28之間隙仍維持於〇.6mm左右之（難以產生磨損） 微小間隙，在兩個構件24、28之間之尤其是輸出軸24之 端部附近可大量地確保潤滑油G1，並且，輸出軸24向被 驅動軸28之嵌入也變得極爲容易。其效果，例如像食品 工廠’在必須頻繁地解並/洗淨該齒輪電動機GM1之工廠 中使用時，特別有益。 於此例中，對象機械之被驅動軸28，是具有限制輸 出軸24之嵌入終端的階梯面28B。階梯面28B是與被驅 • 動軸28呈直角’並藉由抵接於輸出軸24之端面24C，可 封塞空間部SP1(兼任封塞手段）。 接著說明該齒輪電動機GM1之作用。 齒輪電動機GM1向對象機械之被驅動軸28之組裝（ 嵌入）係由以下方式進行··使輸出軸24之軸心01對準 輸送機26之被驅動軸28的軸心02，將齒輪電動機GM1 握持於手中而將輸出軸24之貫通孔24h與鍵32 —起嵌入 在對象機械之被驅動軸28。 於嵌入前，在被驅動軸28的外周28A或（及）輸出 -9- 201014991 軸24的內周24A先塗上潤滑油（G1 )，若在該狀態下將 . 齒輪電動機GM 1組裝到對象機械之被驅動軸2 8，則所塗 上的潤滑油（G1)被擠出而良好地塡充在空間部SP1內 。輸出軸24被嵌入到與被驅動軸28之階梯面2 8B抵接爲 止。 . 該空間部SP1，由於是形成在輸出軸24之端面24C 附近，所以藉由該空間部SP1的存在，其結果爲：在輸出 軸24之端面24C部分處之、輸出軸24之貫通孔24h的半 ❿ 徑Hrle比貫通孔24h之空間部SP1以外之部位的半徑 Hrl還大一 Δ1，因此減速裝置向對象機械之嵌入/裝配極 爲容易。 拭去隨著嵌入而從階梯面28B和輸出軸24之端面 24C溢出之多餘潤滑油（G1 )，在空間部SP1內無間隙地 塡充保持潤滑油G1。 保持該潤滑油G1之空間部SP1係由被驅動軸28之 階梯面28B所封塞，而防止了空氣侵入。因此，有效地抑 參 制空間部SP 1內之潤滑油G 1之經時性的品質劣化（特別 是乾燥）或化學性變化。其結果，藉由保持該潤滑油G1 之空間部SP1的存在，持續長期可靠地防止輸出軸24與 被驅動軸28之內外周24A、28A及形成形狀性之卡合之 鍵32周圍之間之磨損。 其結果，可以兼具以往得擇一權衡之“確保嵌入之容 易性”和“防磨損”。 接著，對有關空間部之形成的變化例進行說明。 -10- 201014991 ’ 於本發明中，空間部之具體形狀不特別限定。作爲空 間部之形狀，例如考慮如圖3所示之型態。 於圖3 ( A)之空間部SP2塡充潤滑油G2之例子中 ’在該空間部SP2之軸方向大致中央的特定部分a處之 半徑方向之高度52h大於在該軸方向兩側部處之半徑方向 之高度52i、52j。即，在輸出軸62之貫通孔62h之空間 部SP2之特定部分A，作爲結果形成有潤滑油積存部52 # 。藉由該潤滑油積存部5 2之存在，即使空間部SP2之軸 方向長度Ls2與前面例子之空間部SP1之軸方向長度Lsl ' 相同’也可以更多地確保潤滑油G2之絕對量，可以更加 抑制潤滑油G2之品質劣化。 潤滑油積存部52之形狀不限於該形狀。此外，潤滑 油積存部52之軸方向之形成位置（特定部分A之軸方向 位置）也不限於圖3 ( A )之位置。潤滑油積存部52之軸 方向之形成位置即便設爲空間部SP2之軸方向最內側也可 • 得到同樣之作用效果。成爲底座之空間形狀也不限於圖3 之例子，例如也可以在後述之圖3 ( B)形成潤滑油積存 部。而且，對於與之前之實施方式相同或功能上相同之部 分，符號也標附相同之符號。在以後之實施方式中也同樣 〇 圖3 ( B )之空間部SP4之潤滑油G4之例子，由於輸 出軸64之貫通孔64h之開口大’所以容易嵌入輸出軸64 ，而且空間部SP4之軸方向長度Ls4更長’所以能夠極力 防止位於潤滑油G4之最深處之部分之品質劣化’對於磨 -11 - 201014991 損也得到有效之抑制作用。 · 於本發明中，空間部之封塞雖未必是必需’但由於封 塞的一方其潤滑油之品質劣化少’所以較佳。在上述之例 子中，被驅動軸28利用階梯面28B作爲封塞手段’但是 被驅動軸不具有階梯面時’例如圖4之（A)所示’附設 用於封塞空間部SP1之V型環（彈性圈：剖面形狀非得 是V字形狀亦可）70即可。V型環70係抵接於與對象機 械之被驅動軸29之外周29A和輸出軸24之端面24C。而 @ 且，在由V型環70、輸出軸24之端面24C、以及被驅動 軸29之外周29A所圍成之微小空間部SP11亦塡充潤滑 油Gl 1爲佳。作爲結果，塡充潤滑油Gl、G11之空間部 成爲 SP1+SP11 。 這樣，藉由配置V型環70、72’ 即使在被驅動軸 29沒有階梯面，也可以封塞空間部SP1、SP3而遮斷空氣 。其結果，可抑制潤滑油G1、G1 1、G3、G 1 3之品質劣化 ，進一步持續長期維持防磨損效果。 ⑩ 而且，在圖4(B)之例子中，基本上與之前之圖2 之實施型態相同，階梯面28B封塞著空間部SP1。因此， 可以說不需要V型環，但是期待進一步之封塞性，因而 與對象機械之被驅動軸28之基部外周面28D和輸出軸24 之端面24C抵接而配置有V型環74。此外，在藉由V型 環74之存在而形成之微小空間部SP21也塡充潤滑油G21 〇 其結果，塡充在空間部SP1內之潤滑油G1大致完全 -12- 201014991 被密封，而可以持續長期極小地維持其品質之劣化。因此 ，防磨損之效果極其高》 而且，這樣，在本發明中，考慮各種型態，但是綜合 性地說，圖2所示之實施型態最佳。這是因爲，在輸出軸 和被驅動軸之間的潤滑油，特別是輸出軸之端部附近以密 封狀態可大量地確保潤滑油G1，並且由於“無階梯”之 空間部收斂，所以輸出軸朝向被驅動軸之嵌入極爲容易且 # 可圓滑地完成。在該意義上，可以說圖2之實施型態最有 效地兼具防磨損和插入之容易性。 產業上之可利用性 如輸送機之減速裝置，可以利用作爲直接安裝在對象 機械之被驅動軸而使用之減速裝置。 【圖式簡單說明】 圖1是表示應用本發明之實施方式之一例之齒輪電動 機（減速裝置）之一部分之俯視剖面圖。 圖2是表示保持上述齒輪電動機之潤滑油之空間部之 圖1箭頭所示π部分之放大剖面圖。 圖3是表示空間部之其他例之相當於圖2之剖面圖》 圖4是表示附設v型環之例子之相當於圖2之剖面 圖0 【主要元件符號說明】 -13- 201014991 GMl :齒輪電動機 1 6 :電動機 18 :減速機 20 :電動機外殼 22 :減速機外殻 24 :輸出軸（中空軸） 24h :貫通孔 24A :內周 2 4 B :端部 24C :端面 2 8 :被驅動軸 28A :外周 28B :階梯面 32 :鍵The invention claims the priority of Japanese Patent Application No. 2008-2 623 93, filed on Oct. 9, 2008. The entire contents of this application are incorporated herein by reference. The present invention relates to a mounting structure of a reduction gear and a reduction gear to a target machine. [Prior Art] Patent Document 1 discloses a structure in which a hollow output shaft of a reduction gear is directly fitted into a driven shaft of a target machine. In this document, a method of using a frictional fastening connection without a gap and a method of engaging by a shape of a key are proposed for the connection between the driven shaft and the output shaft. Patent Document 1: Japanese Patent Laid-Open No. 2001-99177 However, the method of joining the driven shaft and the output shaft by friction is not only required to properly control the fixed torque even after the installation of the reduction gear. Therefore, there is a problem that the reduction gear is attached to the target machine and the maintenance thereof is troublesome. On the other hand, the method of connecting the driven shaft and the output shaft by the engagement of the shape of the key causes a small gap caused by the difference in size between the shaft and the shaft, and a small gap between the engaging portions of the shape. Therefore, there is an inevitable problem of wear and tear. This is because it is necessary to hold the heavy deceleration device while aligning the axis of the driven shaft and the output shaft to embed the reduction gear in the driven shaft 'required in the inner diameter of the output shaft and the driven shaft - 5- 201014991 Ensure a suitable "size difference" between the outer diameters. Ensuring ease of embedding and preventing wear and tear is a trade-off. If the size difference is set to a large extent by considering the ease of embedding, wear is more likely to occur. When the size difference is set small, abrasion is hard to occur, but the insertion work becomes extremely difficult. [Invention] The present invention has been made to eliminate the conventional problems, and the problem is @, which effectively prevents the occurrence of wear. And to simplify the maintenance of the deceleration device when it is embedded or operated to the driven shaft of the target machine. The present invention is a reduction gear for driving a driven shaft of a target machine, and has a hollow output shaft which can be inserted by a driven shaft of the target machine and has a gap with the driven shaft to be coupled to transmit power; The end portion of the output shaft is along the output shaft, and a space portion capable of retaining the lubricating oil is secured between the inner circumference of the output shaft and the outer circumference of the driven shaft, thereby solving the above problems. In the present invention, since a space portion for retaining the lubricating oil is secured between the inner circumference of the hollow output shaft and the outer circumference of the target machine, the air cannot enter the inner side in the axial direction of the space portion. Therefore, even if the drive shaft and the output shaft have a gap and are combined to transmit power, the wear can be surely prevented for a long period of time. Further, since the space portion is formed near the end portion of the output shaft, the outer diameter of the target machine at the end portion of the output shaft and the inner circumference diameter at the end surface of the output shaft are formed by the existence of the space portion. The difference is increased. -6- 201014991 • This makes it extremely easy to assemble the reduction gear to the target machine. Therefore, in the inner side in the axial direction of the space portion, it is possible to reduce the size difference without obstruction, and it is more difficult to cause wear, and there is no fear of noise action or vibration action. Further, in the present invention, according to the gist of the invention, only the so-called "chamfering" processor is not included in the "space portion" of the present invention. Usually, the radius R when chamfering is a radius smaller than 5% of the inner diameter (diameter) φ of the shaft. For example, when the inner diameter (diameter) of the hollow portion of the output shaft is 15 mm to 55 mm, the chamfering radius is about 0.5 mm to 2.5 mm, and even if it is larger, it is less than 5%. Therefore, the chamfer of the range is different from the technical meaning of the "space portion" of the present invention. EFFECTS OF THE INVENTION According to the present invention, it is possible to effectively prevent the occurrence of wear, and it is possible to simplify the embedding or maintenance of the speed reducing device to the driven shaft of the target machine. [Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a partially schematic plan cross-sectional view showing a gear motor (deceleration device) to which an embodiment of the present invention is applied. Fig. 2 is an enlarged cross-sectional view showing a portion of the arrow indicated by the arrow. The gear motor GM1 is mainly composed of an electric motor 16 and a speed reducer 18. The motor 16 is provided with a motor casing 20, and the reducer 18 is provided with a 201014991 speed reducer casing 22. The reducer housing 22 rotatably supports a hollow output shaft 24. The output shaft 24 is provided with a through hole 24h into which the driven shaft 28 can be inserted by a conveyor (object machine: not shown). The power transmission between the output shaft 24 and the driven shaft 28 is a sandwiching key 32, and the "shape of engagement" is performed by a structure having a gap and being coupled to transmit power. Further, instead of the engagement of the shape of the key 32, for example, a shape engagement such as a spline may be employed. In the present invention, the configuration of the motor 16 of the specificity of the gear motor GM1 、 or the speed reduction mechanism of the reducer 18 is not particularly limited. As shown in detail in Fig. 2, a space portion SP1 capable of holding the lubricating oil G1 is secured between the inner circumference 24A of the output shaft 24 and the outer circumference 28A of the driven shaft 28 of the target machine. In this embodiment, the length Lsl of the axial direction X of the space portion SP1 is set to about 1 / 2 of the radius Hr 1 of the through hole 24h of the output shaft 24 (other than the space portion P S1 ). For example, if the inner diameter (Hrlex2) is 15 mm, the axis is about 3 to 5 mm, and if the inner diameter (Hrlex2) is 55 mm, it is about 5 to 10 mm. This is because it is considered that even if the lubricating oil G1 is somewhat dried, it is possible to surely prevent the air from intruding closer to the inner side in the axial direction than the space portion SP1 while preventing wear; it is significantly larger than the above-described normal chamfering R, and relatively ^ A half of the axis of the inner diameter of the size. 5mm~2.5mm. The space portion SP1 is shaped such that the height SPhl of the radial direction R of the space portion SP1 increases as the axial direction X of the output shaft 24 faces the end portion 24B of the output shaft 24. As a result, the radius Hrle of the through hole 24h of the output shaft 24 at the end face 24C of the output shaft 24 -8 - 201014991 is larger than the radius Hrl of the portion other than the space portion SP1 of the through hole 24h by Δ 1 ( If it is considered as a diameter, it is twice the amount of Δ 1 ). For example, when the inner diameter (Hrlex2) is 15 mm to 55 mm, Δ1 is about 1.5 mm to 5 mm 5 mm (about 10% of the inner diameter). This is also significantly larger than the chamfer radius R of 0.5 mm to 2.5 mm (about 5% of the inner diameter). Therefore, it is possible to obtain an effect that the gap between the output shaft 24 near the center portion in the axial direction and the driven shaft 28 of the target machine is maintained at about 66 mm (hard to cause wear). The lubricating oil G1 can be largely ensured in the vicinity of the ends of the output shaft 24 between the members 24, 28, and the insertion of the output shaft 24 into the driven shaft 28 becomes extremely easy. The effect, such as, for example, a food factory, is particularly advantageous when used in a factory that must frequently disassemble/wash the gear motor GM1. In this example, the driven shaft 28 of the target machine is a stepped surface 28B having an embedded terminal that limits the output shaft 24. The step surface 28B is at a right angle to the driven shaft 28 and is closed to the end surface 24C of the output shaft 24, thereby closing the space portion SP1 (also serving as a sealing means). Next, the action of the gear motor GM1 will be described. The assembly (embedding) of the gear motor GM1 to the driven shaft 28 of the target machine is performed by aligning the axis 01 of the output shaft 24 with the axis 02 of the driven shaft 28 of the conveyor 26, and the gear motor GM1 The through hole 24h of the output shaft 24 is held in the hand and is embedded in the driven shaft 28 of the target machine together with the key 32. Before the insertion, the lubricating oil (G1) is first applied to the outer circumference 28A of the driven shaft 28 or (and) the inner circumference 24A of the output -9-201014991 shaft 24, and in this state, the gear motor GM 1 is assembled to the object. The mechanically driven shaft 2 8 is squeezed and the lubricant (G1) applied is well filled in the space portion SP1. The output shaft 24 is fitted into contact with the step surface 28B of the driven shaft 28. Since the space portion SP1 is formed near the end surface 24C of the output shaft 24, the space portion SP1 is present, and as a result, the through hole 24h of the output shaft 24 at the end surface 24C portion of the output shaft 24 is obtained. The radius Hrle of the half-turn diameter Hrle is larger than the radius HR1 of the portion other than the space portion SP1 of the through-hole 24h, so that the insertion/assembly of the reduction gear to the target machine is extremely easy. The excess lubricating oil (G1) overflowing from the step surface 28B and the end surface 24C of the output shaft 24 with the embedding is wiped off, and the lubricating oil G1 is held in the space portion SP1 without any gap. The space portion SP1 holding the lubricating oil G1 is closed by the step surface 28B of the driven shaft 28 to prevent air from entering. Therefore, the quality deterioration (especially drying) or chemical change of the lubricating oil G 1 in the space portion SP 1 is effectively suppressed. As a result, by holding the space portion SP1 of the lubricating oil G1, it is possible to reliably prevent the output shaft 24 from being surrounded by the inner and outer circumferences 24A, 28A of the driven shaft 28 and the periphery of the key 32 that forms the shape. abrasion. As a result, it is possible to combine the "preparation of ease of embedding" and "anti-wear" in the past. Next, a modification of the formation of the space portion will be described. -10-201014991 ′ In the present invention, the specific shape of the space portion is not particularly limited. As the shape of the space portion, for example, a form as shown in Fig. 3 is considered. In the example in which the space portion SP2 of FIG. 3(A) is filled with the lubricating oil G2, the height 52h in the radial direction at the specific portion a substantially at the center in the axial direction of the space portion SP2 is larger than the both sides in the axial direction. Heights 52i, 52j in the radial direction. In other words, the specific portion A of the space portion SP2 of the through hole 62h of the output shaft 62 is formed with the lubricating oil reservoir portion 52# as a result. By the presence of the lubricating oil reservoir 52, even if the axial length Ls2 of the space portion SP2 is the same as the axial length Lsl' of the space portion SP1 of the above-described example, the absolute amount of the lubricating oil G2 can be more ensured. The deterioration of the quality of the lubricating oil G2 is further suppressed. The shape of the lubricating oil reservoir 52 is not limited to this shape. Further, the position in the axial direction of the lubricating oil reservoir 52 (the axial direction position of the specific portion A) is not limited to the position of Fig. 3 (A). The position at which the lubricating oil reservoir 52 is formed in the axial direction can be set to the innermost side in the axial direction of the space portion SP2. The shape of the space to be the base is not limited to the example of Fig. 3. For example, the lubricating oil reservoir may be formed in Fig. 3 (B) which will be described later. Further, for the same or functionally identical parts as in the previous embodiments, the symbols are attached with the same symbols. In the following embodiment, the example of the lubricating oil G4 of the space portion SP4 of Fig. 3 (B) is also used. Since the opening of the through hole 64h of the output shaft 64 is large, the output shaft 64 is easily inserted, and the axis of the space portion SP4 is also inserted. Since the direction length Ls4 is longer, the quality deterioration of the portion located at the deepest portion of the lubricating oil G4 can be prevented as much as possible. The damage is also effectively suppressed for the grinding -11 - 201014991. In the present invention, the sealing of the space portion is not necessarily required, but it is preferable because the quality of the lubricating oil is less deteriorated. In the above-described example, when the driven shaft 28 uses the step surface 28B as the sealing means 'but the driven shaft does not have the step surface', for example, as shown in FIG. 4(A), the V-shaped portion for the plugging space portion SP1 is attached. The ring (elastic ring: the cross-sectional shape may not be a V shape) may be 70. The V-ring 70 is abutted against the outer peripheral surface 29A of the driven shaft 29 of the target machine and the end surface 24C of the output shaft 24. Further, @, the fine space portion SP11 surrounded by the V-ring 70, the end surface 24C of the output shaft 24, and the outer circumference 29A of the driven shaft 29 is preferably filled with the lubricating oil G11. As a result, the space portion of the lubricants G1 and G11 becomes SP1+SP11. Thus, by arranging the V-rings 70, 72', even if the driven shaft 29 has no step surface, the space portions SP1, SP3 can be blocked to block the air. As a result, deterioration of the quality of the lubricating oils G1, G1 1, G3, and G 1 3 can be suppressed, and the anti-wear effect can be further maintained for a long period of time. Further, in the example of Fig. 4(B), basically, the step surface 28B closes the space portion SP1 as in the previous embodiment of Fig. 2 . Therefore, it can be said that the V-ring is not required, but further sealing property is expected. Therefore, the V-ring 74 is disposed in contact with the base outer peripheral surface 28D of the driven shaft 28 of the target machine and the end surface 24C of the output shaft 24. Further, the minute space portion SP21 formed by the presence of the V-ring 74 is also filled with the lubricating oil G21. As a result, the lubricating oil G1 filled in the space portion SP1 is substantially completely -12-201014991, and can be sealed. Maintaining the deterioration of its quality for a long time and minimally. Therefore, the effect of preventing wear is extremely high. Further, in the present invention, various types are considered, but in general, the embodiment shown in Fig. 2 is optimal. This is because the lubricating oil G1 can be largely ensured in a sealed state in the vicinity of the end portion of the output shaft and the driven shaft in the vicinity of the end portion of the output shaft, and the output shaft is converged due to the "stepless" space portion. The insertion towards the driven shaft is extremely easy and can be done smoothly. In this sense, it can be said that the embodiment of Fig. 2 is most effective in preventing wear and insertion. Industrial Applicability As the speed reducer of the conveyor, a speed reducer that is directly mounted on the driven shaft of the target machine can be used. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan sectional view showing a part of a gear motor (deceleration device) to which an embodiment of the present invention is applied. Fig. 2 is an enlarged cross-sectional view showing a portion π shown by an arrow in Fig. 1 for holding a space portion of the lubricating oil of the gear motor. 3 is a cross-sectional view corresponding to FIG. 2 showing another example of the space portion. FIG. 4 is a cross-sectional view corresponding to FIG. 2 showing an example of attaching a v-ring. [Description of main component symbols] -13- 201014991 GMl: Gear Motor 1 6 : Motor 18 : Reducer 20 : Motor housing 22 : Reducer housing 24 : Output shaft (hollow shaft) 24h : Through hole 24A : Inner circumference 2 4 B : End 24C : End face 2 8 : Driven shaft 28A: outer circumference 28B: step surface 32: key