1272344 (1) 玖、發明說明 【發明所屬之技術領域] 本發明是關於內燃機的起動馬達的安裝構造，特別是 關於作成：使起動馬達與曲軸的配設位置接近，讓上述起 動馬達的旋轉軸與上述曲軸的雙軸間距離變短，的這種方 式的上述內燃機的起動馬達的安裝構造。 【先前技術】 以往的內燃機的起動馬達的安裝，相對於該內燃機的 曲軸箱的外殼部所描繪出的外型線，以位於該外型線的外 側的關係來進行安裝，上述起動馬達是被配設在距離曲軸 較遠的位置，讓該起動馬達的旋轉軸與上述曲軸的兩軸間 的距離增加，則從上述起動馬達朝向曲軸的旋轉驅動力的 傳達實質上是經由複數的中間軸來進行（例如，參照專利 文獻1 )。 【專利文獻1】 曰本特開平7 - 2 0 8 1 4 1號公報（第3頁，第！圖及第 2圖） 【發明內容】 〔發明欲解決的課題〕 在上述專利文獻1所記載的以往的起動馬達的安裝動 作，如第5圖及第6圖所圖示，該起動馬達〇2相對於內 .4 - (2) 1272344 燃機的曲軸箱〇 1，相對於該曲軸箱〇 1的側面來看的該箱 體0 1的外殼部所描繪的外型線，是配設成，位於該外型 線的外側（參照第5圖）。 上述起動馬達〇 2與曲軸〇 5是被配設在互相分離的位 置’該起動馬達0 2的旋轉軸〇 2 d與上述曲軸0 5的兩軸部 間距離很大’由上述起動馬達02朝向上述曲軸〇 5的旋轉 驅動力的齒輪傳達，是從與上述起動馬達〇 2的旋轉軸 0 2 d —體的齒輪〇 2 e開始，經由：中間軸〇4 1的齒輪〇 3 ! 、中間軸Oh的齒輪〇32、曲軸〇5的齒輪05!，該驅動力 的傳達是經由中間軸〇4!、〇4 2來進行的（參照第6圖） 〇 如上述，關於上述以往的內燃機的起動馬達的安裝構 造’該起動馬達的主體構造部的大部分或主體構造部的全 體，是位於曲軸箱的側面（與曲軸垂直相交的面部）來看 的該曲軸箱所描繪的外型線的外側，是成爲這樣的配設關 係，曲軸與上述起動馬達的位置是分離的，該起動馬達的 旋轉軸與上述曲軸間的距離較大，從上述起動馬達朝向上 述曲軸的上述旋轉驅動力的傳達，在利用齒輪來傳達的情 況是經由複數支的中間軸，是作成至少經由兩支中間軸。 經由上述複數支中間軸的上述旋轉驅動力的齒輪傳達 ’不只會導致其動力傳達機構的複雜化，也會導致增加齒 輪等的零件數量，而讓機構大型化，並且，上述旋轉驅動 力的傳達效率也會增加。 (3) 1272344 在上述的狀況中，需要著眼於上述內燃機的起動馬達 的安裝構造的改良，特別是關於從該起動馬達朝向上述曲 軸的上述旋轉驅動力的傳達機構的簡化、關於其傳達效率 的提昇、以及減少零件數量讓成本減低等等的改良構造。 〔用以解決課題的手段以及發明的效果〕 本發明，是關於用來解決上述課題的內燃機的起動馬 達的安裝構造的改良，藉由將該起動馬達的安裝儘可能地 接近配設於曲軸，使該起動馬達的旋轉軸與上述曲軸間的 軸間距離縮短，讓從上述起動馬達朝向上述曲軸的旋轉驅 動力的傳達機構簡化之起動馬達的安裝構造， 是具有·起動馬達、曲軸、設置在該曲軸的其中一側 的被動齒輪、設置在該曲軸的另一側的初始傳動齒輪、以 及用來將起動馬達的旋轉驅動力傳達到上述被動齒輪的起 動馬達的齒輪與中間齒輪之起動馬達的安裝構造，其特徵 爲：在曲軸箱內，具有：收容著用來將來自於上述起動馬 達的旋轉驅動力傳達到曲軸的上述中間齒輪與上述被動齒 輪的收容部、以及收容著與上述初始傳動齒輪嚙合的初始 從動齒輪的收容部，在對應於兩收容部所夾著的空間區域 的上述曲軸箱上部的外殼部上形成凹部，在該凹部收容著 上述起動馬達，並且在該起動馬達的收容狀態，用來安裝 上述起動馬達的安裝轂部是被設置在對應於收容著上述初 始從動齒輪的上述收容部的曲軸箱上部的外殼部上。 第1發明，是在曲軸箱內，具有：收容著用來將來自 (4) 1272344 於上述起動馬達的旋轉驅動力傳達到曲軸的上述中間齒輪 與上述被動齒輪的收容部、以及收容著與上述初始傳動齒 輪嚙合的初始從動齒輪的收容部，在對應於兩收容部所夾 著的空間區域的上述曲軸箱上部的外殼部上形成凹部，在 該凹部收容著上述起動馬達，並且在該起動馬達的收容狀 態，用來安裝上述起動馬達的安裝轂部是被設置在對應於 收容著上述初始從動齒輪的上述收容部的曲軸箱上部的外 殻部上； 讓起動馬達與曲軸的配設位置接近’而能大幅度地縮 短起動馬達的旋轉軸與曲軸的軸間距離，當旋轉驅動力從 該起動馬達的旋轉軸傳達到曲軸時，不是像以往的經由複 數支中間軸的方式，而是讓上述旋轉驅動力的傳達經由一 支中間軸來進行，所以可讓用來傳達旋轉驅動力的構造簡 化，減少用來傳達驅動力的零件數量，並且也減少了該旋 轉驅動力在齒輪傳達時所造成的耗損。 第2發明，用來在收容狀態將上述起動馬達安裝在上 述凹部的上述安裝轂部，爲了進行上述起動馬達的安裝， 是設置了 一對在上述曲軸箱上部的外殼部上的位置，以適 合用來收容固定一對安裝用臂部的前端部附近，該一對安 裝用臂部是延伸成：從上述起動馬達的後部的端部或該端 部附近略八字型地擴張， 上述起動馬達是以重心較低且穩定的狀態被收容在上 述凹部，且確實且堅固地被支承著，而由於上述一對安裝 用臂部是呈現八字型，所以對於上述起動馬達起動時的旋 (5) 1272344 轉扭矩的變動的支承力很強，能夠對應於該旋轉扭矩的變 化’而可確保該馬達的安裝狀態。 【實施方式】 以下根據第1圖〜第4圖來說明本發明的實施方式。1272344 (1) Technical Field of the Invention The present invention relates to a mounting structure of a starter motor of an internal combustion engine, and more particularly to a rotation axis of the starter motor in which the starter motor and the crankshaft are disposed close to each other. The mounting structure of the starter motor of the above-described internal combustion engine in such a manner that the distance between the two shafts of the crankshaft is shortened. [Prior Art] The mounting of the starter motor of the conventional internal combustion engine is mounted on the outer side of the outer profile with respect to the outer profile drawn by the outer casing of the crankcase of the internal combustion engine, and the starter motor is Provided at a position far from the crankshaft to increase the distance between the rotating shaft of the starter motor and the two shafts of the crankshaft, the rotational driving force from the starter motor toward the crankshaft is substantially transmitted via a plurality of intermediate shafts. This is performed (for example, refer to Patent Document 1). [Patent Document 1] 曰本特开平 7 - 2 0 8 1 4 1 (3rd page, Fig. 2 and Fig. 2) [Problem to be solved] [Patent Document 1] The mounting operation of the conventional starter motor, as illustrated in Figures 5 and 6, the starter motor 〇2 is relative to the inner crankshaft 〇1 of the internal combustion engine, relative to the crankcase 〇1 The outer profile drawn by the outer casing of the casing 0 1 as viewed from the side of the first aspect is disposed so as to be located outside the outer profile (see Fig. 5). The starter motor 〇2 and the crankshaft 〇5 are disposed at positions separated from each other. The distance between the rotation axis 〇2d of the starter motor 02 and the two shaft portions of the crankshaft 505 is large. The gear transmission of the rotational driving force of the crankshaft 5 is from the gear 〇 2 e of the rotating shaft 0 2 d of the starter motor 〇 2, via the gear 〇 3 ! of the intermediate shaft 〇 4 1 , and the intermediate shaft The gear 〇 32 of the Oh and the gear 05 of the crankshaft 〇 5 are transmitted via the intermediate shafts !4! and 〇4 2 (see Fig. 6). As described above, the above-described conventional internal combustion engine is started. The mounting structure of the motor 'the majority of the main body structure of the starter motor or the entire body structure portion is the outer side of the profile line drawn by the crankcase when viewed from the side surface of the crankcase (the surface perpendicular to the crankshaft) In such an arrangement relationship, the crankshaft is separated from the position of the starter motor, and a distance between the rotation shaft of the starter motor and the crankshaft is large, and the rotational driving force from the starter motor toward the crankshaft is Convey, in the gear case to convey the intermediate shaft via a plurality of branch is made via at least two intermediate shaft. The gear transmission via the above-described rotational driving force of the plurality of intermediate shafts not only complicates the power transmission mechanism, but also increases the number of components such as gears, increases the size of the mechanism, and conveys the rotational driving force. Efficiency will also increase. (3) 1272344 In the above-described situation, it is necessary to pay attention to the improvement of the mounting structure of the starter motor of the internal combustion engine, and in particular to the simplification of the transmission mechanism of the rotational driving force from the starter motor toward the crankshaft, and the communication efficiency thereof. Improved construction that improves and reduces the number of parts to reduce costs. [Means for Solving the Problems and Effects of the Invention] The present invention relates to an improvement in the mounting structure of a starter motor of an internal combustion engine for solving the above problems, and the installation of the starter motor is arranged as close as possible to the crankshaft. The starter motor mounting structure for simplifying the transmission mechanism of the rotational driving force from the starter motor toward the crankshaft, and the starter motor, the crankshaft, and the a driven gear on one side of the crankshaft, an initial transmission gear disposed on the other side of the crankshaft, and a starter motor for transmitting the rotational driving force of the starter motor to the starter motor of the driven gear and the intermediate gear The mounting structure is characterized in that the crankcase includes: a housing portion for transmitting the rotational driving force from the starter motor to the intermediate gear and the driven gear of the crankshaft, and housing and the initial transmission The housing portion of the initial driven gear that meshes with the gear is sandwiched between the two receiving portions A recessed portion is formed in an outer casing portion of the upper portion of the crankcase in the space region, and the starter motor is housed in the recessed portion, and in a state in which the starter motor is housed, a mounting hub portion for mounting the starter motor is provided corresponding to the housing The housing portion of the initial driven gear is provided on an outer casing portion of the upper portion of the crankcase. According to a first aspect of the invention, in the crankcase, the accommodating portion for transmitting the rotational driving force from the (4) 1272344 to the crankshaft to the crankshaft and the driven gear is housed and stored in the crankcase a housing portion of the initial driven gear that meshes with the initial transmission gear has a recess formed in an outer casing portion of the crankcase upper portion corresponding to a space region sandwiched between the two housing portions, and the starter motor is housed in the recess portion, and the starter is mounted The mounting state of the motor, the mounting hub portion for mounting the starter motor is provided on the outer casing portion corresponding to the upper portion of the crankcase that houses the accommodating portion of the initial driven gear; and the arrangement of the starter motor and the crankshaft When the position is close to ', the distance between the rotating shaft of the starter motor and the shaft of the crankshaft can be greatly shortened, and when the rotational driving force is transmitted from the rotating shaft of the starter motor to the crankshaft, it is not like the conventional method of passing through a plurality of intermediate shafts. The transmission of the above-mentioned rotational driving force is performed via an intermediate shaft, so that the structure for transmitting the rotational driving force can be simplified. Reduce the number of parts used to convey the driving force, and also reducing the depletion of the rotational driving force caused by gear conveyed. According to a second aspect of the invention, in the housing state, the starter motor is attached to the mounting boss portion of the recessed portion, and in order to mount the starter motor, a pair of positions on the outer casing portion of the upper portion of the crankcase are provided to fit In the vicinity of the front end portion for accommodating and fixing the pair of attachment arm portions, the pair of attachment arm portions are extended to be slightly splayed from the end portion of the rear portion of the starter motor or the vicinity of the end portion, and the starter motor is The recessed portion is housed in the recessed portion in a state where the center of gravity is low and stable, and is reliably and firmly supported. Since the pair of mounting arm portions are in a figure-eight shape, the rotation of the starter motor is started (5) 1272344 The supporting force of the fluctuation of the torque is strong, and the mounting state of the motor can be ensured in accordance with the change in the rotational torque. [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to Figs. 1 to 4 .
第1圖是顯示沿著內燃機的曲軸箱1的曲軸（沒有圖 不）的方向的一縱剖面圖，在該第1圖是圖示著曲軸箱1 的部分構造，在該圖面是記載著本發明的特徵構造也就是 起動馬達2與其周邊構造部。 而顯示了中間齒輪3，該中間齒輪3是與齒輪2 e嚙 合，齒輪2e則是與上述起動馬達2的旋轉軸2cl爲一體， 該中間園輪3錯由與設置在沒有圖示的曲軸6的其中一側 的被動齒輪5嚙合，來讓上述起動馬達2的旋轉驅動力經 由上述中間齒輪3傳達到上述曲軸6 (參照第2圖）。1 is a longitudinal cross-sectional view showing a direction along a crankshaft (not shown) of a crankcase 1 of an internal combustion engine, and FIG. 1 is a partial view showing a structure of a crankcase 1, and the drawing shows The characteristic configuration of the present invention is also the starter motor 2 and its peripheral structure. The intermediate gear 3 is shown, the intermediate gear 3 is meshed with the gear 2 e, and the gear 2 e is integrated with the rotating shaft 2cl of the starter motor 2, and the intermediate wheel 3 is misplaced and disposed on a crankshaft 6 (not shown). One of the driven gears 5 is engaged to transmit the rotational driving force of the starter motor 2 to the crankshaft 6 via the intermediate gear 3 (see Fig. 2).
上述中間齒輪3，是具有大直徑齒輪部3 ^與小直徑 齒輪部3 b的兩個齒輪部的構造的齒輪，該中間齒輪3的 大直徑齒輪部3 a是做成與上述起動馬達2的旋轉軸2 d爲 一體而與上述齒輪2e嚙合，且具備有該中間齒輪3的小 直徑齒輪部3 b與設置在上述曲軸6的其中一側的上述被 動齒輪5嚙合（參照第2圖）的構造，經由該齒輪5的嚙 合來讓上述起動馬達2的旋轉驅動力傳達到上述曲軸6。 相對於傳達來自於上述起動馬達2的旋轉驅動力的曲 軸6的其中一側，在該曲軸6的另一側，是設置了沒有圖 不的初始傳動齒輪，該初始傳動齒輪是與初始從動齒輪7 (6) 1272344 嚙合著。 在弟1圖〜第3圖，8是離合器，9是變速機構，1 〇 是正時鏈條’ 1 1是氣缸體。 i：：4lS軸箱15在其上部的外殼上是具備有用來安裝 起動馬達2的構造部，該構造部具有由凹部〗a所構成的 構® ’該凹部1 a ’在第1圖的圖示中，是被形成在：作 爲使上述起動馬達2的旋轉軸2d的旋轉驅動力傳達到上 述曲軸6的上述中間齒輪3與上述被動齒輪5的收容部也 就疋i:述曲軸6其中〜側的曲軸箱內空間區域、以及上述 丰刀$台彳專動齒輪與上述初始從動齒輪7的嚙合的該齒輪的收 谷部也/就是上述曲軸6另一側的上述曲軸箱內空間區域所 夾者的該曲軸箱內空間所對應的該箱體1的上述上部的外 殼部上。 用來安裝上述起動馬達2的上述凹部1 a，其剖面形 狀是做成略筒狀的較淺的圓弧狀（參照第3圖），其長軸 方向是以上述筒狀延伸預定長度的構造，在該凹部1 a是 以第1圖〜第3圖所圖示的狀態配設著上述起動馬達2。 上述起動馬達2的上述配設動作，是藉由將該起動馬 達2的配設狀態的其下方部收容在上述凹部1 a所進行的 ，藉此讓該起動馬達2對上述凹部1 a的配設狀態，上述 起動馬達2距離上述曲軸箱1的外殼部所描繪的外型線的 突出量是被抑制了相當程度。 上述起動馬達2對上述凹部1 a的配設狀態，該起動 馬達2，其前部旋轉軸2 d側是藉由以開孔部1 e所構成的 -9- 1272344 · (7) 環爿犬支承部1 d所支承，開孔部1 e是設置成從上述曲軸箱 1上部外殼部突出，其後物2b則是經由從該起動馬達2 的後部2b朝斜後方延伸的一對安裝用臂部2f、2g而被安 # 13 7E在從上述曲軸箱1外殼部突出預定量的安裝轂部 1 b、1 b。 上述起動馬達2前部的利用上述環狀支承部1 d所進 打的支承，更具體來看，是藉由將上述起動馬達2的殼體 部前方突出部2 a，經由環狀的彈性構件2 c (例如0型環 )’嵌合支承在上述曲軸箱1的上述上部外殼部上的凹部 la長軸方向上的設置在其中一側形成端的環狀的開孔部 1 e，的這種方式來進行的。 利用該開孔部i e所進行的上述馬達殼體前方突出部 2 a的肷合支承，實暫上該開孔部1 e的中心是與上述起動 馬達2的旋轉軸2 d的中心一致，而從該關係可推導出上 述開孔部1 e的中心是大致與馬達2的長軸方向中心一致 的關係。 上述起動馬達2後部2b的經由上述一對的安裝用臂 部2f、2g的該馬達2的支承，更具體來說’是經由上述 曲軸箱1的上述上部外殼上的凹部1 a長軸方向上的設置 在另一側形成端的兩個突出相當程度的安裝轂部1 b、1 b 來進行的（參照第4圖）〇 從上述起動馬達2的後邰2b朝向斜後方延伸的上述 〜對的安裝用臂部2 f、2 g的個別則端部，是分別使用螺 拴】c等而被固定在上述兩個安裝轂部ib、ib的上邰，該 - 10- (8) 1272344 兩個安裝轂部1 b、1 b，從第1圖可以看出，是 略對應於上述曲軸箱2內的上述初始傳動齒輪7 該曲軸箱1上部的外殼部上的位置。 從上述起動馬達2後部2 b延伸的上述一對 部2f、2g，如第4圖放大圖示，是從上述起動f 後部2b朝向斜後方呈略八字型地延伸，該一對 部2f、2g的上述八字型的從上述馬達2後部2b 方的延伸，如第3圖及第4圖所圖示，是由於在 裝用臂部2f側有氣缸體1 1，而是一種妥協性的言5 也就是說，因爲上述氣缸體1 1的存在，所 側的安裝用臂部2f相對於上述馬達2的長軸方 向直角方向延伸，另一方面，而爲了要抵抗上述 2起動時的旋轉扭矩而穩定地支承該馬達2，而 以相對於該馬達2的長軸方向直角延伸的安裝用 行支承的矛盾的狀況中，選擇使用了上述八字型 的安裝用臂部2f、2g來做爲支承構造。 經由呈現上述八字型的一對安裝用臂部2 f、 上述兩個安裝轂部1 b、1 b所進行的上述起動馬| 2 b的安裝支承，是藉由從在該起動馬達2的側 其中心線大致相同高度的位置朝向上述斜後方從 延伸的上述一對安裝用臂部2f、2g所進行，藉 馬達2相對於安裝支承位置是將其重心設定在較 ，而能進行穩定的支承，能有助於控制上述起動, 起動時的旋轉扭矩的變化。 被設置在 的上部的 安裝用臂 I達2的 安裝用臂 朝向斜後 右側的安 :計。 以上述右 向無法朝 起動馬達 在要求要 臂部來進 相互延伸 2g而以 I 2後部 面來看與 該馬達2 此，上述 低的位置 達2在 -11 - (9) 1272344 上述起動馬達2 ’是藉由：以其後部2b的上述兩個 安裝轂部1 b、1 b所進行且經由呈現上述八字型延伸的一 對安裝用臂部2f、2g的上述安裝支承、以及其前部的前 方关出邰2 a的上述ί哀狀支取部1 d的上述開孔部1 e所進 行的使該開孔部1 e中心線與馬達2的旋轉軸線一致的上 述支承的三點支承，該起動馬達2實質上會被支承爲水平 狀態，並且相對於上述馬達2的安裝支承位置，該馬達2 的重心位置是在略相同高度的位置或是在稍微下方的位置 ’所以能以穩定且堅固的狀態安裝支承該起動馬達2。 第1圖〜第4圖的圖示的實施方式，由於是如上述的 構xa，起動馬達2貫質上，是被安裝在上述曲軸箱1上部 的外殼部上所形成的凹部1 a且被收容在其下部，距離該 曲軸箱1的外殼部所描繪的外型線的突出量是被控制得較 小0 於疋’ δ亥起動馬達2的女裝位置，會靠近上述曲軸6 ，會讓上述起動馬達2的旋轉軸2 d與上述曲軸6的兩軸 之間的距離縮短，所以從該馬達2的旋轉軸2 d朝向上述 曲軸6的旋轉驅動力的傳達可以經由一支中間軸4來進行 ，其構造可以簡化，且可減少齒輪等的零件數量，也可抑 制旋轉驅動力在傳達上的耗損。 上述起動馬達2的安裝支承，可以經由從上述馬達2 後部2b朝向斜後方八字型擴張地延伸的一對安裝用臂部 2f、2g而以上述安裝轂部lb、lb來進行，所以其支承很 堅固，可以得到能適當對應該馬達2的旋轉扭矩的變化的 -12- (10) 1272344 穩定的安裝支承構造。 上述起動馬達2的安裝支承，是藉由：以及該馬達2 前部的上述環狀支承部1 d所進行的支承、以該馬達2的 後2 b的呈現上述八字型延伸的一對安裝用臂部2 f、2 g 的利用上述安裝轂部1 b、1 b的實質上是水平狀態的三點 支承，該馬達2的支承，是在從上述起動馬達2的側面來 看與中心高度位置大致相同高度的位置，該馬達2的重心 位置相對於上述安裝支承位置是在略相同高度的位置或是 在稍微下方的位置，所以能得到可適當地對應該馬達2起 動時的旋轉扭矩變動的上述起動馬達2的安裝支承構造。 【圖式簡單說明】 第1圖是顯示本發明的主要構造的曲軸箱的縱剖面圖 〇 第2圖是顯示本發明的內燃機的槪觀狀況的從與曲軸 垂直的其中一方向來看的剖面圖。 第3圖是顯示本發明的內燃機的槪觀狀況的從與曲軸 垂直的另一方向來看的剖面圖。 第4圖是本發明的起動馬達安裝部的放大圖。 第5圖是以剖面來顯示以往的內燃機的槪觀狀況與曲 軸箱的一部分構造部的顯不圖。 第6圖是以剖面來顯示以往發明的主要構造部的視圖 -13- (11) 1272344 【圖號說明】 1 :曲軸箱 1 a :凹部 1 b :安裝轂部 1 c :螺栓 1 d :環狀支承部 1 e :開孔部 2 :起動馬達 2a :起動馬達殼體的前方突出部 2b :起動馬達後部 2c :環狀的彈性體 2 d :旋轉軸 2e :與旋轉軸一體的齒輪部 2f、2g :安裝用臂部 3 :中間齒輪 3 a :大直徑齒輪部 3 b :小直徑齒輪部 4 :中間軸 5 :曲軸的被動齒輪 6 :曲軸 7 :初始從動齒輪 8 :離合器 9 :變速機構 1 0 :正時鏈條 -14 - 1272344The intermediate gear 3 is a gear having a configuration of two gear portions of a large diameter gear portion 3^ and a small diameter gear portion 3b, and the large diameter gear portion 3a of the intermediate gear 3 is formed with the above-described starter motor 2 The rotating shaft 2d is integrally meshed with the gear 2e, and the small-diameter gear portion 3b including the intermediate gear 3 meshes with the driven gear 5 provided on one side of the crankshaft 6 (see FIG. 2). The structure transmits the rotational driving force of the starter motor 2 to the crankshaft 6 via the meshing of the gear 5. With respect to one side of the crankshaft 6 that conveys the rotational driving force from the above-described starter motor 2, on the other side of the crankshaft 6, there is provided an initial transmission gear that is not shown, and the initial transmission gear is initially driven Gear 7 (6) 1272344 is engaged. In the drawings 1 to 3, 8 is the clutch, 9 is the shifting mechanism, and 1 〇 is the timing chain '1 1 is the cylinder block. The i::4lS axle box 15 is provided with a structural portion for mounting the starter motor 2 on the upper casing, and the structural portion has a configuration of the recessed portion A 'the recessed portion 1 a ' in the first figure In the above description, the accommodating portion of the intermediate gear 3 and the driven gear 5 that transmits the rotational driving force of the rotating shaft 2d of the starter motor 2 to the crankshaft 6 is also described. The inner space region of the crankcase and the valley portion of the gear that meshes with the first driven gear 7 and/or the inner space region of the crankcase on the other side of the crankshaft 6 The inner space of the upper portion of the casing 1 corresponding to the space in the crankcase is clamped. The recessed portion 1a for mounting the starter motor 2 has a cross-sectional shape of a shallow circular arc shape (see FIG. 3), and a long axis direction thereof is a predetermined length extending in the cylindrical shape. The starter motor 2 is disposed in the recessed portion 1a in a state illustrated in Figs. 1 to 3 . The arrangement operation of the starter motor 2 is performed by accommodating the lower portion of the starter motor 2 in the recessed portion 1a, thereby allowing the starter motor 2 to match the recessed portion 1a. In a state where the amount of protrusion of the starter motor 2 from the outer casing of the crankcase 1 is suppressed to a considerable extent. In the state in which the starter motor 2 is disposed in the recessed portion 1a, the starter motor 2 has a front side rotating shaft 2d side which is constituted by the opening portion 1e - 9 - 1272344 · (7) The support portion 1 d is supported, and the opening portion 1 e is provided to protrude from the upper outer casing portion of the crankcase 1 , and the rear object 2 b is a pair of attachment arms extending obliquely rearward from the rear portion 2 b of the starter motor 2 . The portions 2f and 2g are protruded by a predetermined amount of the mounting boss portions 1b and 1b from the outer casing portion of the crankcase 1. More specifically, the front portion of the starter motor 2 is supported by the annular support portion 1d, and more specifically, the front portion 2a of the casing portion of the starter motor 2 is passed through an annular elastic member. 2c (for example, a 0-ring) is fitted to the annular opening portion 1e in which the end portion is formed on one side of the concave portion 1a of the upper casing portion of the crankcase 1 The way to do it. The center of the opening portion 1 e is aligned with the center of the rotating shaft 2 d of the starter motor 2 by the twisting and supporting of the motor housing front protruding portion 2 a by the opening portion ie. From this relationship, it can be inferred that the center of the opening portion 1 e is substantially in line with the center of the motor 2 in the longitudinal direction. The support of the motor 2 via the pair of mounting arm portions 2f and 2g of the rear portion 2b of the starter motor 2 is more specifically "through the longitudinal direction of the recess 1a on the upper casing of the crankcase 1. Provided by the two mounting ends 1 b, 1 b protruding to the opposite side of the other side forming the end (refer to FIG. 4), the above-mentioned pair of diagonally extending from the rear cymbal 2b of the starter motor 2 The respective end portions of the mounting arm portions 2 f and 2 g are fixed to the upper jaws of the two mounting hub portions ib and ib by using screws φ or the like, respectively, the 10- 10 (8) 1272344 Mounting the hub portions 1b, 1b, as can be seen from Fig. 1, corresponds slightly to the position on the outer casing portion of the upper portion of the crankcase 1 of the initial transmission gear 7 in the crankcase 2. As shown in the fourth diagram, the pair of portions 2f and 2g extending from the rear portion 2b of the starter motor 2 are slightly splayed from the starter rear portion 2b toward the oblique rear portion, and the pair of portions 2f and 2g are extended. The extension of the octagonal shape from the rear portion 2b of the motor 2, as shown in Figs. 3 and 4, is due to the fact that the cylinder block 1 is on the side of the arm portion 2f for mounting, but a compromise is made. In other words, the mounting arm portion 2f on the side extends in a direction perpendicular to the longitudinal direction of the motor 2 due to the presence of the cylinder block 11 described above, and in order to withstand the rotational torque at the time of starting the above 2, In the case where the motor 2 is stably supported, the mounting arm portions 2f and 2g of the figure-eight type are selected as the support structure in a contradiction between the mounting row supports extending at right angles to the longitudinal direction of the motor 2. . The mounting support of the starting horse | 2 b by the pair of mounting arm portions 2 f and the two mounting boss portions 1 b and 1 b that exhibit the above-described splayed shape is from the side of the starter motor 2 The position of the center line having substantially the same height is performed toward the pair of mounting arm portions 2f and 2g extending obliquely rearward, and the center of gravity of the motor 2 is set to be relatively large with respect to the mounting support position, thereby enabling stable support. It can help to control the change of the above-mentioned starting and starting torque. The mounting arm of the upper part of the mounting arm I is set to 2, and the mounting arm is oriented toward the right side of the slope. In the above right direction, it is impossible to extend 2g to the starter motor at the required arm portion and to the motor 2 with the I 2 rear face. The low position is up to 2 at -11 - (9) 1272344. ' is by the above-described two mounting bosses 1 b and 1 b of the rear portion 2b, and the above-described mounting support of the pair of mounting arm portions 2f, 2g extending in the above-described splayed shape, and the front portion thereof a three-point support of the support that allows the center line of the opening portion 1 e to coincide with the rotation axis of the motor 2 by the opening portion 1 e of the above-described smashing portion 1 d of the front side of the 邰 2 a, The starter motor 2 is substantially supported in a horizontal state, and the position of the center of gravity of the motor 2 is at a position of a slightly higher height or a position slightly lower than the mounting support position of the motor 2 described above, so that it can be stabilized and strong. The state is mounted to support the starter motor 2. In the illustrated embodiment of the first to fourth figures, since the starter motor 2 is mechanically connected, the starter motor 2 is a recessed portion 1a formed on the outer casing portion of the upper portion of the crankcase 1, and is Included in the lower portion thereof, the amount of protrusion of the profile line drawn from the outer casing portion of the crankcase 1 is controlled to be smaller than 0. The position of the women's wear of the motor 2 is close to the crankshaft 6 and will be Since the distance between the rotating shaft 2 d of the starter motor 2 and the two shafts of the crankshaft 6 is shortened, the transmission of the rotational driving force from the rotating shaft 2 d of the motor 2 toward the crankshaft 6 can be transmitted via the intermediate shaft 4 . The construction can be simplified, and the number of parts such as gears can be reduced, and the loss of the rotational driving force can be suppressed. The mounting and supporting of the starter motor 2 can be performed by the pair of mounting arm portions 2f and 2g extending from the rear portion 2b of the motor 2 toward the obliquely rear splayed shape, and the mounting hub portions 1b and 1b can be used. Sturdy, a -12-(10) 1272344 stable mounting support structure that properly accommodates changes in the rotational torque of the motor 2 can be obtained. The mounting support of the starter motor 2 is supported by the annular support portion 1d at the front of the motor 2, and the pair of mountings in which the rear bb of the motor 2 is extended in the splayed shape. The arm portions 2 f and 2 g are supported by a substantially horizontal three-point support using the above-described mounting boss portions 1 b and 1 b. The support of the motor 2 is at a center height position from the side of the starter motor 2 . At the position of substantially the same height, the position of the center of gravity of the motor 2 is at a position of a slightly higher height or a position slightly lower than the mounting support position, so that it is possible to appropriately respond to the fluctuation of the rotational torque when the motor 2 is started. The mounting support structure of the starter motor 2 described above. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a crankcase of a main structure of the present invention. FIG. 2 is a cross-sectional view showing a state of view of the internal combustion engine of the present invention as viewed from one direction perpendicular to the crankshaft. Figure. Fig. 3 is a cross-sectional view showing the observing condition of the internal combustion engine of the present invention as seen from the other direction perpendicular to the crankshaft. Fig. 4 is an enlarged view of the starter motor mounting portion of the present invention. Fig. 5 is a cross-sectional view showing the appearance of the conventional internal combustion engine and a part of the structural portion of the crankcase. Fig. 6 is a cross-sectional view showing the main structure of the conventional invention-13-(11) 1272344 [Description of the figure] 1 : Crankcase 1 a : Recess 1 b : Mounting hub 1 c : Bolt 1 d : Ring The support portion 1e: the opening portion 2: the starter motor 2a: the front protruding portion 2b of the starter motor casing: the starter motor rear portion 2c: the annular elastic body 2d: the rotary shaft 2e: the gear portion 2f integrated with the rotary shaft 2g: mounting arm 3: intermediate gear 3 a : large diameter gear portion 3 b : small diameter gear portion 4 : intermediate shaft 5 : driven gear 6 of crankshaft : crankshaft 7 : initial driven gear 8 : clutch 9 : shifting Agency 1 0 : Timing Chain - 14 - 1272344