1359903 Ο) 九、發明說明 【發明所屬之技術領域】 本發明係有關於一種裝設在諸如機車或三輪車輛上之 類的小型車輛上的內燃機，特別是有關於引擎汽缸大致上 水平設置而具有一用來偵測引擎運轉情形之感測器的內燃 機。 【先前技術】 在裝設於機車上而具有水平設置之汽缸的內燃機中， 其已知有一種引擎，其中的潤滑油溫度感測器係設置於汽 缸的下半部（參見日本專利JP-A-2004-293348 )。 此日本專利JP-A-2004-2 93 3 48中所揭露的油溫度感測 器係裝設在自左側向右側做向上傾斜設置之汽缸的下半部 內，而該油溫度感測器有一部份係傾斜地向下突伸。因此 ，被該車輛前輪所帶起的泥水、飛石及類似者會撞擊至該 油溫度感測器上，因之而沾污或損傷油溫度感測器。 爲處理此一情形，油溫度感測器的前半部必須要以一 特殊的感測器蓋子來加以遮蓋住。藉由在內燃機上裝設此 種特殊專用的感測器蓋子，即可保護該油溫度感測器免於 並飛石或類似者的撞擊。 因此，有必要製做此專用的感測器蓋子，並將此感測 器蓋子裝設在內燃機上，而零件的數量會因之而增加，也 需要有將該感測器蓋子裝設在內燃機上的安裝作業，故而 會推高製造成本。 -5- (2) (2)1359903 【發明內容】 本發明係針對此一情形而開發的，而本發明的目的在 於提供一種裝設在小型車輛上的內燃機，其可保護以突伸 方式裝設在汽缸之感測器免於飛石或類似者之撞擊而無需 特別的構件及特別的安裝作業。 爲達成前述之目的，本發明提供一種供裝設在小型車 輛上的內燃機，其具有一大致上水平設置而朝向車輛的前 方的汽缸，以及一設置在該引擎上以偵測該引擎的運轉情 形的感測器：其中該感測器係以突出的方式裝設於該汽缸 之一側；以及該車輛之一組件係裝設於該感測器的下方。 根據本發明，該組件係可接收在該車輛移動過程中自 地面彈跳起來的飛石或類似者，因之而可保護該感測器。 因此，其將無需設置特殊之用來保護該感測器免於受飛石 及類似者撞擊的保護構件，而用來安裝該特殊之保護構件 的安裝作業也不需要，因此可以達成製造成本的降低。 該車輛的該組件可以是該引擎之排氣管，延伸於該感 測器的下方。在此情形中，該排氣管可接收在該車輛移動 過程中自地面彈跳起來的飛石或類似者，因之而可保護該 感測器。 最好是將一構成該排氣管之一部份的觸媒裝置設置於 該感測器的下方。在此情形中，該觸媒裝置在該排氣管的 區域內具有最大的寬度，因此可以確實地保護該感測器免 於飛石或類似者的撞擊。 -6- (3) (3)1359903 該組件可以是該車輛之一支架部件來。在此情形中’ 該車體支架部件可接收在該車輛移動過程中自地面彈跳起 來的飛石或類似者，因之而可保護該感測器。 該支架部件可以是一下支架及一延伸於一對左側及右 側下支架間之橫構件之一者。在此情形中’該下支架或該 橫構件可以保護該感測器免於飛石或類似者的撞擊’而無 需使用特殊的保護構件。 一冷卻鰭片構件該汽缸之一部份’係形成於一位在該 感測器前方的位置處。在此情形中’即使是有飛入之飛石 或類似者存在時，該汽缸的該冷卻鰭片也可在無需使用特 殊的保護構件的情形下接收該等飛入的飛石等，進而可以 保護該感測器。 該冷卻鰭片可以形成爲L形，自該汽缸之一側表面延 伸至一下方表面。在此情形中，其可以透過維持該冷卻鰭 片之高強度而確實地保護該感測器免於飛入之飛石或類似 者的撞擊。 該感測器可裝設於該汽缸的旁側，而大致上水平而平 行於地面自該汽缸的旁側突伸出。在此情形中，該感測器 可以輕易地裝設至該汽缸上。 該感測器可以一種能自下方接觸之的方式裝設在該汽 缸的下方部位上。在此種情形中，該感測器可以輕易地自 下方裝設至該汽缸的下方部位上。 下文中將配合於所附的圖式來詳細地說明本發明。 1359903 ⑷ [實施方式】 第1圖中以側視圖顯示出一機車1，其上裝設著本發 明的內燃機2 0。 此機車1具有一車體支架，係構造如下。一主支架3 自一頭管2處沿著向後且傾斜向下之方向延伸，一對左側 及右側樞接板4垂直向下延伸，並固定在主支架3的後側 末端部位上，一對左側及右側後支架5沿著向後且傾斜向 上的方向自該主支架3的後側部位延伸出，以及副支架6 分別延伸於該等樞接板4與該等後支架5之間。 —前輪9可轉動地支撐於一前叉8的下方末端，該前 叉係以一種可讓該前叉8由一轉向手把7加以轉向的方式 裝設在頭管2上。 另一方面，擺臂11係以一種每一擺臂11均有一前側 末端樞轉地支撐於一樞軸10上的狀態，以可垂直擺動的 方式分別連接至樞接板4上，一後輪12係可轉動地支擦 在擺臂11的後側末端上。一後避震器13夾置於每一擺臂 1 1與每一上後支架5之間。 一燃料箱1 4裝設在該對左側及右側後支架5的前側 部位之間，一容置箱1 5係支撐於位在燃料箱1 4至後支架 5後側部位間的零件上，而一座位1 6裝設在容置箱15上 。該座位1 6可以開啓及關閉。 內燃機20係以懸吊的方式支撐於樞接板4及一向下 突伸出之引擎吊掛件17上，該引擎吊掛件係固定在主支 架3上稍微位於主支架3中心點後方的位置處。內燃機2〇 (5) 1359903 係一四行程單汽缸的內燃機。 內燃機20係裝設在車體支架而使得內燃機20係大 上水平朝向前側的方向。也就是說，汽缸體22、汽缸 23及汽缸頭蓋24係以此順序自一曲柄軸箱21朝向前方 置的。 一輸出軸25相對於機車自位在曲柄軸箱21的後側 位之變速箱處相左延伸，一驅動鏈輪26固定在輸出軸 的末端部位處，一驅動鏈28延伸於該驅動鏈輪26與一 置於後輪12之軸上的被動鏈輪27之間，以使得此內燃 20的驅動動力能傳遞至後輪12上。 一進氣管30自大致水平而向前設置的汽缸頭23的 方表面向上延伸，且進氣管30透過結合於噴射器內的 流閥本體31連接至裝設於主支架3上的空氣清淨器32 〇 如第1圖及以平面圖顯示出內燃機20之主要零件 第2圖中所示，一排氣管33自汽缸頭23的下方表面向 延伸，再向前彎折，而後向左彎折1 8 0度，再後延伸。 氣管33係沿著曲柄軸箱21的下方表面向後延伸。一觸 裝置34在汽缸頭23及汽缸體22的傾斜向左及向下位 處連接至排氣管33上，而位在曲柄軸箱21的前方。排 管33連接至一設在曲柄軸箱21後方的消音器35上。 消音器35係由一設置曲柄軸箱21與後輪12之間 寬度加大前側部位3 5 a及一自該寬度加大前側部位3 5 a 沿著後輪1 2的右側向後延伸的寬度縮減後側部位3 5b 致 頭 設 部 25 套 機 上 節 上 的 下 排 媒 置 氣 的 處 所 (6) (6)1359903 構成的（參見第2圖）。動消音器35係支撐於樞接板4 上’而排氣管3 3則連接至寬度加大前側部位3 5 a的前側 表面的左側部位上。 轉向手把7係由一把手蓋60加以遮蓋住，頭管2的 前側部位則由一前蓋61加以遮蓋住，主支架3的該部位 及其左側及右側部位均由一腿部擋件62加以遮蓋住，而 容置箱15周邊及下方部位則是由一本體蓋63加以遮蓋住 。再者，一前擋泥板64自前輪9的上方部位延伸至其後 側部位，而遮蓋住前輪9，而後擋泥板65則後輪12的傾 斜上方遮蓋之。 參閱第3圖，本發明的內燃機20採用OHC鏈閥致動 機構驅動系統，一凸輪鏈42用來將引擎曲柄軸40的旋轉 動作傳遞至裝設於汽缸頭23上的凸輪軸41上。在內燃機 20的左側部位上設有該使用凸輪鏈42之閥致動機構的動 力傳遞機構。 第4圖顯示出汽缸體22自汽缸頭23結合至該汽缸體 2 2之一側視之的前視圖。在此，在汽缸孔2 2 a的左側（第 4圖的右側）有一凸輪鏈室43，係形成爲垂直伸長而大致 上矩形的形狀。在此，凸輪鏈室43亦是延續至汽缸頭蓋 2 4內。 通過凸輪鏈室43的凸輪鏈42係延伸於套置於曲柄軸 40上的驅動鏈輪40a與套置於凸輪軸41上之被動鏈輪 4 1 a之間。 沿著凸輪鏈42被驅動鏈輪4〇a拉引之一側（下方側 -10- (7) (7)1359903 )，設有一固定鏈導件45,其自下方支撐著凸輪鏈42的 下方延伸部位，並導引該下方延伸部位，而在凸輪鏈42 被驅動鏈輪40a推出之一側（上方側）的上方延伸部位上 ，設有一凸輪鏈緊鏈器46，自上方提供凸輪鏈42張力。 在凸輪鏈室43的固定鏈導件45下方，形成有一油回返通 道或溝槽43a。 如第3圖中所示，一具貫穿孔的安裝凸座2 2b形成於 汽缸體22的左側表面的下方後側部位上，一潤滑油溫度 感測器50則自安裝凸座22b之貫穿孔的左側大致上水平 地插置於其內。 該油溫度感測器50 (用來偵測引擎之運轉情形的感測 器）的右半部（第4圖中所視的左半部內側部位）係插入 至該貫穿孔內。油溫度感測器50具有一溫度偵測部位50a ，形成在其內側遠端末端處而突伸進入至油回返通道43a 內。油溫度感測器50的左半部（第4圖中的右半部外側 部位）固定在汽缸體22的左側壁上，而使得該左半部大 致上水平而平行於地面向左突出。 因此，在汽缸體22係大致上水平設置的內燃機20內 ，本發明所使用的油溫度感測器50可以偵測可供所有油 回返流動通過之油回返通道43 a內的油溫度。此種配置方 式可使其得以正確地測量油溫度。 在汽缸體22的表面上形成有多個突出的冷卻鰭片22 f ，而在油溫度感測器50之左半部中外露出的前側部位上 亦形成有冷卻鰭片22F。冷卻鰭片22F係形成爲自汽缸體 -11 - (8) 1359903 22之左側表面至下方表面的L形形狀’因此可以增強冷 卻鰭片2 2F的強度（參見第4圖）。 可以透過形成在緊鄰於油溫度感測器50前方的冷卻 鰭片22F來保護油溫度感測器50免於受到飛過來的飛石 、異物及類似者的撞擊。 在油溫度感測器50的下方設置有該觸媒裝置34’其 構成排氣管33的一部份。觸媒裝置34係設置在排氣管33 φ 中排氣管33的直徑被加大的部位處，而油溫度感測器50 則是設置在該具有較大側向寬度及大縱向長度的觸媒裝置 34的上方。 ' 透過此種結構，觸媒裝置34可以接受特別是因爲前 輪9在機車移動過程中的轉動而造成自地面跳起之飛石及 類似者而保護油溫度感測器50。因此，其將可以保護油溫 度感測器50。 基於此等理由之故，其將無需設置特殊之用來保護油 φ 溫度感測器50免於受飛石及類似者撞擊的保護裝置，也 不需要進行保護裝置的安裝作業，因此可以減低製造成本 〇 腿部擋件62是設置在自汽缸頭23向左側突出之油溫 度感測器50(參見第1圖及第2圖）的左側及斜前方處， 因此可以透過腿部擋件62來保護油溫度感測器50免於受 到傾斜方向飛過來的飛石及類似者的撞擊。 接下來將配合第5圖及第6圖來討論在具有與機車1 之車體結構不同之車體結構的機車80上裝設相同之內燃 -12- (9) 1359903 機20的第二實施例。 機車80係爲鞍跨騎式車輛，其中一主支架82自一 管81處向後延伸，而同時一對下支架83自傾斜向下延 而具有一種可分割成左側及右側部位的結構。 該等下支架83在下方末端處彎折而向後延伸，該 下支架83的後側末端係連接至一對自主支架82中間部 傾斜向下延伸之左側及右側中支架8 4的向後彎曲的下 末端上。 —對左側及右側座位軌條8 5自主支架8 2向後延伸 而側支架8 6則延伸於中支架8 4的彎曲部位與座位軌條 之間。 一前輪88係可轉動地支撐於一可轉向地設置在頭 81上的前叉87的下方末端上，擺臂90係裝設於以可搖 方式裝設在中支架84之彎曲部位上的樞接板89上。每 擺臂90均具有一前側末端，樞轉地支撐於該樞接板89 ’而後輪9 1則係可轉動地支撐於該等擺臂90的後側末 上。 一後避震器92夾置於每一擺臂90的後側部位與每 上座位軌條85之間。 一燃料箱93支撐於該主支架82上，而一座位94 裝設在設置於燃料箱93後側的座位軌條85上。 內燃機20 (在此係以與第一實施例中相同的參考標 加以標示）具有與第一實施例中相同的結構，係支撐於 引擎吊掛件93及以突出之方式裝設於中支架84上之樞 頭 伸 等 位 方 85 管 擺 上 端 則 號 接 -13- (10) (10)1359903 板89上。 —進氣管95自內燃機20的汽缸頭23向上延伸，並 透過一節流閥本體96而進一步向後延伸。進氣管95係連 接至裝設於座位軌條85前側部位的下方的空氣清淨器97 上。 一排氣管98位在此機車之右側’自汽缸頭23的向下 延伸，而後彎折，再沿著曲柄軸箱21的下方表面進一步 向後延伸。該排氣管98係連接至裝設於後輪9 1右側的加 長消音器99上。 在此裝設於如前所述的機車80上的內燃機20中，一 油溫度感測器50以突出的方式裝設於汽缸體22的下方部 位而沿著汽缸體22的左側表面，使得油溫度感測器50朝 向左側而傾斜向下的方向。 由於油溫度感測器5 0係自傾斜下方側裝設的，油溫 度感測器50可自下方接觸到，並可輕易地組裝及固定在 定位上。 在此，油溫度感測器50係裝設成使該油溫度感測器 50以大致上水平突伸出而平行於地面。 在緊鄰於油溫度感測器50前側的位置處設有冷卻鳍 片22F，因此冷卻鰭片22F可以保護油溫度感測器50免 於受到飛石、異物或類似者的撞擊。 在油溫度感測器50下方傾斜向前的位置上，一橫管 100延伸該對左側及右側下管83之間，一橫板101則在該 橫管1 00的後方延伸於該對左側及右側下管83之間。該 -14- (11) (11)1359903 橫板101具有一前側末端，連接至該橫管100上。 在此種架構下，橫板101可自下方遮蓋住油溫度感測 器50，且該橫板101及該橫管100可以接受特別是因爲前 輪9在機車移動過程中的轉動而造成自地面跳起之飛石及 類似者，因之而可保護油溫度感測器50。 基於此等理由之故，其將無需設置特殊之用來保護油 溫度感測器50免於受飛石及類似者撞擊的保護裝置，也 不需要進行保護裝置的安裝作業，因此可以達成製造成本 的降低。 如上所述，油溫度感測器50可由橫板1 01、橫管1 00 及冷卻鰭片22 F加以保護而免於飛石及類似者的撞擊。但 是，爲能得到完整的保護，第5圖及第6圖中所示的防護 構件1 1 0可以事先設置，以防止飛石及類似者彈跳進入汽 缸體22與橫管100間的空間內。 防護構件110具有一近端末端，係以螺栓111牢固地 固定至。22的下方表面上。防護構件110係該近端末端向 後並傾斜向下延伸，並突伸進入至形成於油溫度感測器5 0 與橫管1 0 0間的空間內。 因此，防護構件110可接收彈跳進入至汽缸體22與 橫管1 00間之空間內的飛入之飛石及類似者，因此可以防 止該等飛入之飛石及類似者進一步進入至該空間的後側部 位內，故可確實地保護該油溫度感測器50。 該防護構件1 1 〇係一小型構件，因此此防護構件1 1 0 的安裝是相當的簡單 -15- (12) (12)1359903 【圖式簡單說明】 第1圖是一裝設有根據本發明實施例之內燃機的機車 的側視圖。 第2圖是該機車的部份平面圖。 第3圖是該內燃機之主要部份的側視圖，但有一部份 已略去。 第4圖是一汽缸體在自與汽缸頭接合之表面視之的前 視圖。 第5圖是根據本發明另一實施例之機車的側視圖。 第6圖是該根據本發明另一實施例之機車的主要部份 自下方視之的底視圖。 【主要元件之符號說明】 1 :機車 2 :頭管 3 :主支架 4 :樞接板 5 :後支架 6 :副支架 7 :轉向手把 8 :前叉 9 ·則輪 1 〇 ·樞軸 -16- (13) (13)1359903 11 :擺臂 12 :後輪 13 :後避震器 14 :燃料箱 15 :容置箱 1 6 :座位 17 :引擎吊掛件 20 :內燃機 2 1 :曲柄軸箱 22 :汽缸體 2 2 a :汽缸孔 22b :安裝凸座 22f :冷卻鰭片 22F :冷卻鰭片 23 :汽缸頭 24 :汽缸頭蓋 25 :輸出軸 體器 輪輪 本淨 鏈鏈鏈管閥清管 動動動氣流氣氣 驅被驅進節空排 (14) (14)1359903 34 :觸媒裝置 35 :消音器 3 5 a :寬度加大前側部位 3 5b :寬度縮減後側部位 40 :曲柄軸 40a :驅動鏈輪 41 :凸輪軸 4 1 a :被動鍵輪 42 :凸輪鏈 43 :凸輪鏈室 4 3 a :油回返通道 4 5 :鏈導件 46 :凸輪鏈緊鏈器 5 0 :油溫度感測器 5〇a :溫度偵測部位 60 :把手蓋 6 1 :前蓋 62 :腿部擋件 63 :本體蓋 64 :前擋泥板 6 5 :後擋泥板 80 :機車 81 :頭管 82 :主支架 -18 1359903 下支架 中支架 座位軌條 側支架 前叉 前輪 樞接板 擺臂 後輪 後避震器 燃料箱 座位 進氣管 節流閥本體 空氣清淨器 排氣管 消音器 =橫管 :橫板 :防護構件 :螺栓BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine mounted on a small vehicle such as a locomotive or a three-wheeled vehicle, particularly with respect to an engine cylinder being substantially horizontally disposed. An internal combustion engine for detecting a sensor operating condition of the engine. [Prior Art] In an internal combustion engine having a horizontally disposed cylinder mounted on a locomotive, there is known an engine in which a lubricating oil temperature sensor is disposed in a lower half of a cylinder (see Japanese Patent JP-A). -2004-293348 ). The oil temperature sensor disclosed in the Japanese Patent Publication No. JP-A-2004-2 93 3 48 is installed in the lower half of the cylinder which is inclined upward from the left side to the right side, and the oil temperature sensor has a portion. The parts protrude obliquely downward. Therefore, muddy water, flying stones and the like carried by the front wheel of the vehicle may hit the oil temperature sensor, thereby contaminating or damaging the oil temperature sensor. To handle this situation, the front half of the oil temperature sensor must be covered with a special sensor cover. By installing such a special dedicated sensor cover on the internal combustion engine, the oil temperature sensor can be protected from the impact of flying stones or the like. Therefore, it is necessary to manufacture the dedicated sensor cover, and the sensor cover is installed on the internal combustion engine, and the number of parts is increased, and the sensor cover is also required to be installed in the internal combustion engine. The installation work on the top will push up the manufacturing cost. -5- (2) (2) 1359903 [Invention] The present invention has been developed in view of this situation, and an object of the present invention is to provide an internal combustion engine mounted on a small vehicle, which can be protected in a protruding manner. The sensor located in the cylinder is free of impact from flying stones or the like without special components and special installation work. To achieve the foregoing objects, the present invention provides an internal combustion engine for a small vehicle having a cylinder disposed substantially horizontally toward the front of the vehicle, and a engine disposed on the engine to detect the operation of the engine. The sensor: wherein the sensor is mounted on one side of the cylinder in a protruding manner; and one of the components of the vehicle is mounted below the sensor. According to the present invention, the assembly can receive flying stones or the like that bounce off the ground during the movement of the vehicle, thereby protecting the sensor. Therefore, it is not necessary to provide a special protective member for protecting the sensor from being hit by flying stones and the like, and the mounting work for mounting the special protective member is not required, so that the manufacturing cost can be reduced. . The assembly of the vehicle may be the exhaust pipe of the engine extending below the sensor. In this case, the exhaust pipe can receive a flying stone or the like that bounces off the ground during the movement of the vehicle, thereby protecting the sensor. Preferably, a catalytic device constituting a portion of the exhaust pipe is disposed below the sensor. In this case, the catalyst device has the largest width in the region of the exhaust pipe, so that the sensor can be surely protected from the impact of flying stones or the like. -6- (3) (3) 13599903 This component can be one of the vehicle's bracket components. In this case, the body bracket member can receive a flying stone or the like that bounces from the ground during the movement of the vehicle, thereby protecting the sensor. The bracket member can be a lower bracket and one of the cross members extending between the pair of left and right lower brackets. In this case, the lower bracket or the cross member can protect the sensor from the impact of a flying stone or the like without the use of a special protective member. A cooling fin member is formed in a portion of the cylinder at a position in front of the sensor. In this case, the cooling fins of the cylinder can receive the flying flying stones or the like without using a special protective member even when there is a fly-in flying stone or the like, thereby protecting the Sensor. The cooling fins may be formed in an L shape extending from one side surface of the cylinder to a lower surface. In this case, it can surely protect the sensor from flying into the flying stone or the like by maintaining the high strength of the cooling fin. The sensor can be mounted to the side of the cylinder and protrude substantially horizontally from the side of the cylinder. In this case, the sensor can be easily mounted to the cylinder. The sensor can be mounted on the lower portion of the cylinder in such a manner as to be contacted from below. In this case, the sensor can be easily mounted from below to the lower portion of the cylinder. The invention will be described in detail hereinafter in conjunction with the accompanying drawings. 1359903 (4) [Embodiment] A locomotive 1 is shown in a side view in Fig. 1, and an internal combustion engine 20 of the present invention is mounted thereon. This locomotive 1 has a vehicle body bracket and is constructed as follows. A main bracket 3 extends from a tube 2 in a rearward and oblique downward direction, and a pair of left and right pivoting plates 4 extend vertically downward and are fixed to the rear end portion of the main bracket 3, a pair of left sides And the right rear bracket 5 extends from the rear side portion of the main bracket 3 in a rearward and oblique upward direction, and the sub-bracket 6 extends between the pivotal panels 4 and the rear brackets 5, respectively. The front wheel 9 is rotatably supported at the lower end of a front fork 8, which is attached to the head pipe 2 in such a manner that the front fork 8 is steered by a steering handle 7. On the other hand, the swing arm 11 is connected to the pivoting plate 4 in a vertically swingable state in a state in which each of the swing arms 11 is pivotally supported on a pivot shaft 10, and a rear wheel is vertically swingable. The 12 series is rotatably attached to the rear end of the swing arm 11. A rear shock absorber 13 is interposed between each of the swing arms 1 1 and each of the upper rear brackets 5. A fuel tank 14 is disposed between the front side portions of the pair of left and right rear brackets 5, and a receiving box 15 is supported on the components located between the fuel tank 14 and the rear side of the rear bracket 5, and A seat 16 is mounted on the receiving box 15. The seat 16 can be opened and closed. The internal combustion engine 20 is suspended in a suspended manner on the pivot plate 4 and a downwardly projecting engine hanger 17, which is fixed to the main bracket 3 at a position slightly behind the center point of the main bracket 3. Internal combustion engine 2〇 (5) 1359903 is a four-stroke single-cylinder internal combustion engine. The internal combustion engine 20 is mounted on the vehicle body bracket such that the internal combustion engine 20 is oriented substantially horizontally toward the front side. That is, the cylinder block 22, the cylinder 23, and the cylinder head cover 24 are oriented forward from a crankcase 21 in this order. An output shaft 25 extends leftward relative to the locomotive at the gearbox at the rear side of the crankcase 21, a drive sprocket 26 is fixed at the end of the output shaft, and a drive chain 28 extends from the drive sprocket 26 Between a passive sprocket 27 placed on the shaft of the rear wheel 12, the driving power of the internal combustion 20 can be transmitted to the rear wheel 12. An intake pipe 30 extends upward from a square surface of the cylinder head 23 disposed substantially horizontally forward, and the intake pipe 30 is connected to the air installed in the main bracket 3 through the flow valve body 31 coupled to the injector. 32. As shown in FIG. 1 and a plan view showing the main part of the internal combustion engine 20, as shown in FIG. 2, an exhaust pipe 33 extends from the lower surface of the cylinder head 23, and is bent forward and then bent to the left. 1 8 0 degrees, then extended. The air tube 33 extends rearward along the lower surface of the crankcase 21. The one-touch device 34 is connected to the exhaust pipe 33 at the inclined left and right positions of the cylinder head 23 and the cylinder block 22, and is positioned in front of the crankcase 21. The discharge pipe 33 is connected to a muffler 35 provided at the rear of the crankcase 21. The muffler 35 is reduced in width by a width-increasing front side portion 3 5 a between the crankcase 21 and the rear wheel 12 and a width extending from the width-increasing front side portion 3 5 a along the right side of the rear wheel 12 2 . The rear side portion 3 5b is formed by the head (25) (6) 1359903 (see Fig. 2) of the lower medium in the upper section of the machine. The muffler 35 is supported on the pivot plate 4 and the exhaust pipe 3 3 is connected to the left side portion of the front side surface of the wide front side portion 35 a. The steering handle 7 is covered by a handle cover 60, and the front side portion of the head tube 2 is covered by a front cover 61. The portion of the main bracket 3 and its left and right portions are both supported by a leg stop 62. Covered, and the peripheral portion and the lower portion of the receiving box 15 are covered by a body cover 63. Further, a front fender 64 extends from the upper portion of the front wheel 9 to the rear portion thereof to cover the front wheel 9, and the rear fender 65 covers the upper portion of the rear wheel 12 obliquely. Referring to Fig. 3, the internal combustion engine 20 of the present invention employs an OHC chain valve actuating mechanism drive system, and a cam chain 42 is used to transmit the rotational motion of the engine crankshaft 40 to the camshaft 41 mounted on the cylinder head 23. The power transmission mechanism of the valve actuating mechanism using the cam chain 42 is provided on the left side portion of the internal combustion engine 20. Figure 4 shows a front view of the cylinder block 22 from the cylinder head 23 to one side of the cylinder block 2 2 . Here, on the left side (the right side of Fig. 4) of the cylinder hole 2 2 a, there is a cam chain chamber 43 which is formed into a shape which is vertically elongated and substantially rectangular. Here, the cam chain chamber 43 also continues into the cylinder head cover 24. The cam chain 42 passing through the cam chain chamber 43 extends between the drive sprocket 40a that is placed over the crankshaft 40 and the passive sprocket 41a that is placed over the camshaft 41. One side of the drive chain sprocket 4A is pulled along the cam chain 42 (lower side -10 (7) (7) 1359903), and a fixed chain guide 45 is provided which supports the lower side of the cam chain 42 from below. The extension portion guides the lower extension portion, and on the upper extension portion of the cam chain 42 pushed out by one side (upper side) of the drive sprocket 40a, a cam chain tensioner 46 is provided, and the cam chain 42 is provided from above. tension. Below the fixed chain guide 45 of the cam chain chamber 43, an oil return passage or groove 43a is formed. As shown in FIG. 3, a through-hole mounting boss 2 2b is formed on the lower rear side portion of the left side surface of the cylinder block 22, and a lubricating oil temperature sensor 50 is self-mounting through the through hole of the mounting boss 22b. The left side is inserted substantially horizontally therein. The right half of the oil temperature sensor 50 (the sensor for detecting the operation of the engine) (the inner portion of the left half as viewed in Fig. 4) is inserted into the through hole. The oil temperature sensor 50 has a temperature detecting portion 50a formed at the inner distal end thereof and projecting into the oil return passage 43a. The left half of the oil temperature sensor 50 (the outer half of the right half in Fig. 4) is fixed to the left side wall of the cylinder block 22 such that the left half is substantially horizontal and protrudes leftward in parallel with the ground. Therefore, in the internal combustion engine 20 in which the cylinder block 22 is substantially horizontally disposed, the oil temperature sensor 50 used in the present invention can detect the temperature of the oil in the oil return passage 43a through which all of the oil flows back. This configuration allows it to properly measure the oil temperature. A plurality of protruding cooling fins 22f are formed on the surface of the cylinder block 22, and cooling fins 22F are also formed on the front side portions exposed in the left half of the oil temperature sensor 50. The cooling fins 22F are formed in an L-shape from the left side surface to the lower surface of the cylinder block -11 - (8) 1359903 22 so that the strength of the cooling fins 2 2F can be enhanced (see Fig. 4). The oil temperature sensor 50 can be protected from impact by flying flying stones, foreign objects, and the like through the cooling fins 22F formed in front of the oil temperature sensor 50. Below the oil temperature sensor 50, the catalyst device 34' is disposed to form a portion of the exhaust pipe 33. The catalyst device 34 is disposed at a portion where the diameter of the exhaust pipe 33 is increased in the exhaust pipe 33 φ, and the oil temperature sensor 50 is disposed at the contact having a larger lateral width and a large longitudinal length. Above the media device 34. Through this configuration, the catalyst device 34 can receive the oil temperature sensor 50, particularly because of the flying stones and the like which are caused by the rotation of the front wheel 9 during the movement of the locomotive. Therefore, it will be able to protect the oil temperature sensor 50. For these reasons, it is not necessary to provide a special protection device for protecting the oil φ temperature sensor 50 from being hit by flying stones and the like, and it is not necessary to perform the installation work of the protection device, thereby reducing the manufacturing cost. The leg rest 62 is disposed at the left side and the oblique front of the oil temperature sensor 50 (see FIGS. 1 and 2) protruding from the cylinder head 23 to the left side, and thus can be protected by the leg stopper 62. The oil temperature sensor 50 is protected from the impact of flying stones and the like that are flying in an oblique direction. Next, a second implementation of installing the same internal combustion-12-(9) 1359903 machine 20 on a locomotive 80 having a vehicle body structure different from that of the locomotive 1 will be discussed with reference to FIGS. 5 and 6. example. The locomotive 80 is a saddle straddle type vehicle in which a main bracket 82 extends rearward from a tube 81 while a pair of lower brackets 83 extend downward from the slant to have a structure that can be divided into left and right sides. The lower brackets 83 are bent at the lower end and extend rearward. The rear end of the lower bracket 83 is connected to the left side of the pair of autonomous brackets 82 and the left side of the right side bracket and the right side of the middle bracket 84. On the end. - For the left and right seat rails 8 5 the autonomous brackets 8 2 extend rearwardly and the side brackets 8 6 extend between the curved portions of the middle brackets 8 4 and the seat rails. A front wheel 88 is rotatably supported on a lower end of a front fork 87 steerably disposed on the head 81, and the swing arm 90 is mounted on a pivoting portion of the intermediate bracket 84 Board 89. Each of the swing arms 90 has a front end pivotally supported on the pivot plate 89' and a rear wheel 91 is rotatably supported on the rear side of the swing arm 90. A rear shock absorber 92 is interposed between the rear side portion of each swing arm 90 and each of the upper seat rails 85. A fuel tank 93 is supported on the main bracket 82, and a seat 94 is mounted on the seat rail 85 disposed on the rear side of the fuel tank 93. The internal combustion engine 20 (herein labeled with the same reference numerals as in the first embodiment) has the same structure as that of the first embodiment, is supported by the engine hanger 93 and is attached to the intermediate bracket 84 in a protruding manner. The pivotal extension of the equipotential square 85 tube upper end is connected to the-13- (10) (10) 1359903 board 89. The intake pipe 95 extends upward from the cylinder head 23 of the internal combustion engine 20 and further extends rearward through the throttle body 96. The intake pipe 95 is connected to an air cleaner 97 installed below the front side portion of the seat rail 85. An exhaust pipe 98 is located on the right side of the locomotive' from the lower end of the cylinder head 23, and then bent, and further extends rearward along the lower surface of the crankcase 21. The exhaust pipe 98 is connected to an extension muffler 99 mounted on the right side of the rear wheel 91. In the internal combustion engine 20 mounted on the locomotive 80 as described above, an oil temperature sensor 50 is attached to the lower portion of the cylinder block 22 in a protruding manner along the left side surface of the cylinder block 22, so that the oil The temperature sensor 50 is tilted downward toward the left side. Since the oil temperature sensor 50 is mounted from the lower side of the tilt, the oil temperature sensor 50 can be accessed from below and can be easily assembled and fixed on the positioning. Here, the oil temperature sensor 50 is mounted such that the oil temperature sensor 50 projects substantially horizontally parallel to the ground. The cooling fins 22F are provided at positions immediately adjacent to the front side of the oil temperature sensor 50, so the cooling fins 22F can protect the oil temperature sensor 50 from impact by flying stones, foreign objects or the like. In a position inclined forward of the oil temperature sensor 50, a horizontal tube 100 extends between the pair of left and right lower tubes 83, and a horizontal plate 101 extends rearward of the horizontal tube 100 to the left side and Between the right lower tube 83. The -14-(11)(11)1359903 transverse plate 101 has a front end that is coupled to the cross tube 100. In this configuration, the cross plate 101 can cover the oil temperature sensor 50 from below, and the cross plate 101 and the cross tube 100 can be taken from the ground especially because the front wheel 9 rotates during the movement of the locomotive. The flying stone and the like can protect the oil temperature sensor 50. For these reasons, it is not necessary to provide a special protection device for protecting the oil temperature sensor 50 from being hit by flying stones and the like, and it is not necessary to perform the installation work of the protection device, so that the manufacturing cost can be achieved. reduce. As described above, the oil temperature sensor 50 can be protected from the impact of the flying stone and the like by the cross plate 101, the cross tube 100 and the cooling fins 22F. However, in order to obtain complete protection, the shield members 1 10 shown in Figs. 5 and 6 may be previously provided to prevent the flying stones and the like from bouncing into the space between the cylinder block 22 and the cross tube 100. The guard member 110 has a proximal end that is securely secured thereto by bolts 111. 22 on the lower surface. The shield member 110 has the proximal end extending rearward and obliquely downwardly and projecting into a space formed between the oil temperature sensor 50 and the cross tube 100. Therefore, the protective member 110 can receive flying flying stones and the like that jump into the space between the cylinder block 22 and the cross tube 100, so that the flying flying stones and the like can be prevented from further entering the space. The oil temperature sensor 50 can be reliably protected in the side portion. The protective member 1 1 is a small component, so the installation of the protective member 1 1 0 is quite simple -15- (12) (12) 1359903 [Simple description of the drawing] Figure 1 is a set according to the present A side view of a locomotive of an internal combustion engine of an embodiment of the invention. Figure 2 is a partial plan view of the locomotive. Fig. 3 is a side view of the main part of the internal combustion engine, but a part thereof has been omitted. Figure 4 is a front elevational view of a cylinder block as viewed from the surface engaged with the cylinder head. Fig. 5 is a side view of a locomotive according to another embodiment of the present invention. Fig. 6 is a bottom view of the main part of the locomotive according to another embodiment of the present invention as seen from the lower side. [Symbol description of main components] 1 : Locomotive 2 : Head tube 3 : Main bracket 4 : Pivot board 5 : Rear bracket 6 : Sub bracket 7 : Steering handle 8 : Front fork 9 · Wheel 1 〇 · Pivot - 16- (13) (13)1359903 11 : Swing arm 12 : Rear wheel 13 : Rear shock absorber 14 : Fuel tank 15 : Housing box 1 6 : Seat 17 : Engine hanger 20 : Internal combustion engine 2 1 : Crank axle box 22: cylinder block 2 2 a : cylinder hole 22b: mounting boss 22f: cooling fin 22F: cooling fin 23: cylinder head 24: cylinder head cover 25: output shaft body wheel net chain chain tube valve pigging The moving air flow is driven into the empty row (14) (14) 1359903 34: Catalyst device 35: Silencer 3 5 a : Widening front part 3 5b: Width reduction Rear part 40 : Crank axis 40a: drive sprocket 41: camshaft 4 1 a : passive key wheel 42 : cam chain 43 : cam chain chamber 4 3 a : oil return passage 4 5 : chain guide 46 : cam chain tensioner 5 0 : oil temperature Sensor 5〇a: Temperature detecting portion 60: Handle cover 6 1 : Front cover 62: Leg block 63: Body cover 64: Front fender 6 5: Rear fender 80: Locomotive 81: Head tube 82: main bracket -18 1359903 in the lower bracket Bracket Seat rail Side bracket Front fork Front wheel Pivot plate Swing arm Rear wheel Rear shock absorber Fuel tank Seat Intake pipe Throttle body Air purifier Exhaust pipe Silencer = Cross tube : Horizontal plate : Protective member : Bolt