201013034 六、發明說明： 【發明所屬之技術領域】 本發明是關於：在可自由旋轉地被汽缸頭所支承的凸 輪軸上，固設著汽門驅動凸輪，並安裝有凸輪輪廓不同於 該汽門驅動凸輪的異體凸輪，而可切換「使連動、連結於 引擎汽門的汽門驅動構件，從動於前述汽門驅動凸輪」的 狀態、及「使前述汽門驅動構件從動於與前述凸輪軸一起 旋轉的前述異體凸輪」的狀態之引擎的可變驅動汽門裝置 【先前技術】 專利文獻1揭示一種引擎的可變驅動汽門裝置，該引 擎的可變驅動汽門裝置是在一體設有汽門驅動凸輪之凸輪 軸上鄰接於前述汽門驅動凸輪的位置，將凸輪輪廓不同於 汽門驅動凸輪的異體凸輪安裝成不能相對旋轉，而可切換 φ 「使異體凸輪與凸輪軸及汽門驅動凸輪一體旋轉作動」的 狀態、及「使異體凸輪相對於凸輪軸及汽門驅動凸輪而自 由旋轉」的狀態，而這樣的技術已爲大眾所知悉。 〔專利文獻1〕日本特開2007 — 146740號公報 【發明內容】 〔發明欲解決之課題〕 然而，在上述專利文獻1所揭示的可變驅動汽門裝置 中，是藉由將不能與凸輪軸相對旋轉的鎖銷’嵌合在設於 -5- 201013034 異體凸輪的鎖銷嵌合部，而促使異體凸輪與凸輪軸及汽門 驅動凸輪一體旋轉，而在鎖銷嵌合於前述鎖銷嵌合部時產 生敲擊聲。 本發明是有鑑於上述的問題所硏發而成的發明，本發 明的目的是提供一種：既能避免凸輪軸的大型化，又能抑 制敲擊聲產生之引擎的可變驅動汽門裝置。 〔解決課題手段〕 爲了達成上述目的，請求項1所記載的發明，是在可 自由旋轉地被汽缸頭所支承的凸輪軸上，固設有汽門驅動 凸輪，並且安裝凸輪輪廓不同於該汽門驅動凸輪的異體凸 輪，而可切換：使連動、連結於引擎汽門的汽門驅動構件 從動於前述汽門驅動凸輪的狀態、及使前述汽門驅動構件 從動於與前述凸輪軸一起旋轉的前述異體凸輪的狀態之引 擎的可變驅動汽門裝置，其特徵爲：在前述凸輪軸設有： 與該凸輪軸同軸地延伸的中心孔；及連結於該中心孔之内 周面與前述凸輪軸之外周面間，並在前述凸輪軸的軸方向 上長距離延伸的導引孔，可在軸方向上移動且同軸地*** 前述中心孔内的桿、及可在軸方向上移動並安裝於前述凸 輪軸外周的前述異體凸輪，是由貫穿前述導引孔的連結銷 所連結’在爲了使前述汽門驅動構件從動於前述汽門驅動 凸輪而使前述異體凸輪從前述汽門驅動凸輪隔離的非作動 位置、與爲了使前述汽門驅動構件從動於前述異體凸輪而 使前述異體凸輪接近前述汽門驅動凸輪的作動位置之間， -6- 201013034 於軸方向上驅動前述桿的桿驅動手段，是連結於 而請求項2所記載的發明，其特徵爲：除了 所記載之發明的構造外，在透過第1軸承及第2 自由旋轉地被汽缸頭所支承之前述凸輪軸的第1 承間，「用來驅動進氣汽門開閉」的進氣凸輪； 驅動前述引擎汽門之排氣汽門開閉」的前述汽門 ，也就是指排氣凸輪，是將前述進氣凸輪配置在 φ 側而設成一體；用來驅動前述排氣汽門，而使燃 出之排放氣體的一部份回到前述燃燒室的排放氣 用凸輪，也就是指前述異體凸輪，是被配置在前 輪與第2軸承之間。 不僅如此，請求項3所記載的發明，其特徵 請求項1所記載之發明的構造外，前述凸輪軸一 排氣凸輪，該排氣凸輪是用來驅動前述引擎汽門 門開閉的前述汽門驅動凸輪；及進氣凸輪，該進 φ 用來驅動進氣汽門開閉；用來驅動前述排氣汽門 燒室所排出之排放氣體的一部份回到前述燃燒室 體再循環用凸輪，也就是指前述異體凸輪，是被 述排氣凸輪與前述進氣凸輪之間。 而實施形態的排氣汽門2 5是對應於本發明 門，實施形態的排氣側搖臂3 9是對應於本發明 動構件，實施形態的第1滾珠軸承44是對應於 第1軸承，實施形態的第2滾珠軸承45則對應 的第2軸承。 前述桿。 ‘請求項 1 軸承而可 及第2軸 及「用來 驅動凸輪 第1軸承 燒室所排 體再循環 述排氣凸 爲：除了 體設有： 之排氣汽 氣凸輪是 ，而使燃 的排放氣 配置在前 的引擎汽 的汽門驅 本發明的 於本發明 201013034 〔發明效果〕 根據請求項1所記載的發明，「可在軸方向上移動並 安裝於凸輪軸外周」的異體凸輪、和***「同軸地設於凸 輪軸的中心孔」的桿，是藉由貫穿「連結於中心孔之内周 面與凸輪軸之外周面間，且在前述凸輪軸的軸方向上長距 離延伸的導引孔」的連結銷所連結，而能以「利用驅動手 段在軸方向上對桿進行驅動」的簡易構造’來切換「使汽 門驅動構件從動於汽門驅動凸輪」的狀態、以及「使汽門 驅動構件從動於異體凸輪」的狀態，使異體凸輪平時與凸 輪軸一起旋轉，故能抑制切換作動時敲擊聲的產生’此外 ，藉由將桿收容於凸輪軸内，可避免凸輪軸的大型化。 此外，根據請求項2所記載的發明，在「透過第1及 第2軸承而可自由旋轉地被汽缸頭所支承之凸輪軸」的第 1及第2軸承之間，「用來驅動進氣汽門開閉」的進氣凸 輪、與「用來驅動排氣汽門開閉」的排氣凸輪，是將進氣 凸輪配置於第1軸承側而設成一體，並將作爲排放氣體再 循環用凸輪的異體凸輪，配置在排氣凸輪及第2軸承之間 ，故可在對凸輪軸形成良好的軸支承的狀態下’配置異體 凸輪。 不僅如此，根據請求項3所記載的發明，在凸輪軸一 體設有：用來驅動排氣汽門開閉的排氣凸輪、及用來驅動 進氣汽門開閉的進氣凸輪，並將作爲排放氣體再循環用凸 輪的異體凸輪配置在排氣凸輪及進氣凸輪之間’故能有效 地利用排氣凸輪與進氣凸輪間的空間來配置異體凸輪，而 -8 - 201013034 避免因異體凸輪的配置而導致凸輪軸之軸長度增加的情形 【實施方式】 以下，參考圖面說明本發明的實施形態。 第1圖〜第8圖是顯示本發明之第1實施形態的圖面 ，第1圖爲引擎之重要部分的縱剖面圖，第2圖爲第1圖 φ 中2— 2線的剖面圖，第3圖爲第2圖中箭號3所標示之 部份的放大圖，第4圖是減壓停止狀態下之第3圖中4 - 4 線的剖面圖，第5圖是顯示進氣汽門與排氣汽門之開啓汽 門揚程特性的圖，第6圖是顯示減壓停止狀態下之第3圖 中6-6線的放大剖面圖，第7圖爲減壓裝置的分解立體 圖，第8圖是對應於減壓啓動狀態下之第6圖的剖面圖。 首先，在第1圖及第2圖中，該引擎的引擎本體11， 是譬如搭載於機車的引擎本體，前述引擎本體11具備： Φ 汽缸體12，該汽缸體12具有可供活塞15自由滑動地嵌合 的汽缸孔16;和汽缸頭13，該汽缸頭13在其與前述汽缸 體1 2之間形成有面向前述活塞1 5之頂部的燃燒室1 7，且 結合於汽缸體12;和頭蓋14，該頭蓋14是從前述汽缸體 1 2的相反側結合於該汽缸頭1 3 ;及曲軸箱（圖面中未顯 示）’該曲軸箱是從前述汽缸頭13的相反側結合於前述 汽缸體12。 在前述汽缸頭13設有：在其一側面形成開口的進氣 埠1 8、及在汽缸頭1 3的另一側面形成開口的排氣埠〗9， -9- 201013034 形成有通往前述進氣埠18之進氣通路20的進氣管21是 連接於前述汽缸頭13，並在該進氣管21附設有燃料噴射 閥22。 此外，用來切換前述進氣埠18與前述燃燒室17間之 連通、遮斷的進氣汽門24;及用來切換前述排氣埠19與 前述燃燒室1 7間之連通、遮斷的排氣汽門25 ’是可開閉 作動地配設於前述汽缸頭1 3，進氣汽門24及排氣汽門25 是由汽門彈簧26、27朝汽門關閉方向彈推。不僅如此’ @ 在前述汽缸頭13還安裝有前端面向前述燃燒室17的火星 塞23。 一倂參考第3圖，前述進氣汽門24及前述排氣汽門 25，是藉由收容在「形成於前述汽缸頭13與前述頭蓋14 間之汽門驅動室28」的可變驅動汽門裝置29A所開閉驅 動，該可變驅動汽門裝置29A，是被配置在前述進氣汽門 24與排氣汽門25間，並且具備：凸輪軸32，該凸輪軸32 設有進氣凸輪30與排氣凸輪31;和異體凸輪33，該異體 @ 凸輪33的凸輪輪廓是不同於排氣凸輪31 ’並可在前述凸 輪軸32的外周移動於軸方向上且安裝成不能相對旋轉； 和減壓裝置34A，該減壓裝置34A是將前述排氣凸輪31 挾持於其與前述異體凸輪33間’並安裝於前述凸輪軸32 ;和進氣側與排氣側擺動軸3 6、3 7 ’該進氣側與排氣側擺 動軸36、37具有與前述凸輪軸32平行的軸線’且被汽缸 頭1 4所支承；和進氣側搖臂3 8 ’該進氣側搖臂3 8是從動 於前述進氣凸輪30 ’並用來驅動進氣汽門24開閉’且能 -10- 201013034 自由搖動地被進氣側擺動軸3 6所支承；及排氣側搖臂3 9 ，該排氣側搖臂3 9是從動於前述排氣凸輪3 1、前述異體 凸輪33或者前述減壓裝置34A的減壓凸輪35，並用來驅 動排氣汽門25開閉，且可自由搖動地被排氣側擺動軸3 7 所支承。 前述汽缸頭13 —體設有：第1支承部42，該第1支 承部42具有第1軸承孔40;及第2支承部43，該第2支 φ 承部43具有與第1軸承孔40同軸的第2軸承孔41。前述 凸輪軸32的其中一端部，是在與第1軸承孔40的内周之 間夾介著作爲第1軸承的第1滾珠軸承44，而可旋轉地由 第1支承部42所支承，前述凸輪軸32之靠近另一端的部 分，則可自由旋轉地貫穿第2軸承孔41，在第2軸承孔 41的内周及凸輪軸32之間，夾設有作爲第2軸承的第2 滾珠軸承45。而凸輪軸32是被壓入第1及第2滾珠軸承 44、45的内輪，前述進氣凸輪30及前述排氣凸輪31則形 φ 成：將進氣凸輪30配置於第1滾珠軸承44側，並將排氣 凸輪31配置於第2滾珠軸承45側，且在第1及第2滾珠 軸承44、45間一體形成於前述凸輪軸32，前述減壓裝置 34A是被配置在前述進氣凸輪30與前述排氣凸輪31之間 ，異體凸輪33，是在排氣凸輪31挾持於前述減壓裝置 34A的減壓凸輪35之間的位置，安裝於前述凸輪軸32。 來自於圖面中未顯示之曲柄軸的旋轉力，是透過定時 傳動機構（timing transmission mechanism) 47 而傳達至 前述凸輪軸32，該定時傳動機構47，是將無間斷狀的凸 -11 - 201013034 輪鏈條50捲掛於：被固定在來自於前述凸輪軸32的第2 滾珠軸承45之突出端部的從動鏈輪48、及被固設在前述 曲柄軸的驅動鏈輪（圖面中未顯示）所形成，凸輪鏈條50 是可行走地被收納於鏈條行走通路51內，該鏈條行走通 路51是遍及汽缸體12、汽缸頭13及頭蓋14所形成。 檢視第1圖，前述進氣凸輪30及前述排氣凸輪31具 有：圓弧狀的基圓部30a、31a，該圓弧狀的基圓部30a、 31a是以'前述凸輪軸32的軸線作爲中心；及高位部30b、 31b，該高位部30b、31b是較基圓部30a、31a更突出於 外側方，且連結於基圓部30a、31a的周方向兩端之間； 且前述進氣凸輪30及前述排氣凸輪31是藉由使高位部 30b、31b的相位錯開，而一體地形成於前述凸輪軸32。 在被前述進氣側擺動軸36支承成可搖動的進氣側搖 臂38的其中一端部，軸支著滾動接觸於進氣凸輪30的滾 子52 ’在該進氣側搖臂36的另一端部，抵接於進氣汽門 24之桿身末端24a的挺桿螺絲53，是可調整進退位置地 螺合。此外，在被前述進氣側擺動軸37支承成可搖動的 進氣側搖臂39的其中一端部，軸支著滾動接觸於進氣凸 輪31的滾子54’在該進氣側搖臂39的另—端部，抵接於 進氣汽門25之桿身末端25a的挺桿螺絲55，是可調整進 退位置地螺合。 前述滾子52、54沿著旋轉軸線的寬度，是被設定成 大於前述進氣凸輪30及前述排氣凸輪31在沿著凸輪軸32 軸線之方向上的寬度，滾子52、54是滾動接觸於：前述 -12- 201013034 進氣凸輪30及前述排氣凸輪31在沿著凸輪軸32軸線 方向上的中央部。此外’前述滾子52、54被配置成： 中一部份在從凸輪軸32之軸線方向觀看的視角中形成 疊，且在滾子52、54間保持著特定的間隔’以避免滾 52、54相互干涉，進氣凸輪30及排氣凸輪31’也保持 對應於上述間隔的間隔，而設於凸輪軸32。 不僅如此，在前述排氣側搖臂39的其中一端部， φ 抵接於前述異體凸輪33的抵接部39a、及可抵接於前述 壓裝置34A之減壓凸輪35的抵接部39b，是將前述滾 54挾持於其間而設成一體’兩抵接部39a、39b至少在 輪軸3 2側的端部形成：從沿著凸輪軸3 2軸線的方向觀 ，與前述滾子54的外周一致、或者較前述外周更突出 前述凸輪軸3 2側。 前述異體凸輪33，可在：接近前述排氣凸輪31且 接於排氣側搖臂39之抵接部39a的作動位置（第3圖 • 以實線表示的位置）、及從前述排氣凸輪31分離而避 與前述排氣側搖臂3 9之抵接部3 9a抵接的非作動位置 第3圖中以虛線表示的位置）間，移動於前述凸輪軸 的軸線方向上，並在凸輪軸32的外周嵌裝成無法對該 輪軸32的軸線週圍形成轉動。 一倂參考第4圖，前述異體凸輪33，是用來驅動前 排氣汽門2 5開啓汽門的排放氣體再循環用凸輪，可使 燃燒室1 7所排出之排放氣體的一部份回到燃燒室1 7， 具有：將前述凸輪軸32的軸線作爲中心的圓弧狀基圓 之 其 重 子 著 可 減 子 凸 看 於 抵 中 免 ( 32 凸 述 由 其 部 -13- 201013034 33a、及從基圓部33a朝外側方突出的高位部33b，異體凸 輪33的基圓部33a，是形成較排氣凸輪31的基圓部31a 更小的外徑。 此外，高位部33b，是在對應於進氣凸輪30中高位部 30b之關閉汽門末期的相位，從前述基圓部33a略微突出 的部分，高位部33b之周方向兩端是形成圓滑的曲線並連 接於前述基圓部33a。而當異體凸輪33移動至「抵接於排 氣側搖臂39之抵接部39a」的作動位置時，排氣側搖臂 39在藉由排氣凸輪31的高位部31b產生轉動而促使排氣 汽門25執行關閉汽門的動作後，是藉由抵接於排氣凸輪 31的基圓部31a而保持關閉汽門的狀態，但進氣汽門24 在關閉汽門作動時的末期，是如第5圖所示，由異體凸輪 33的高位部33b使排氣側搖臂39產生些微的轉動進而促 使排氣汽門25些微地開啓汽門。如此一來’可在壓縮行 程中使排氣汽門25暫時開啓，而由排放氣體促使混合氣 在燃燒室1 7内之燃燒的活性化，可達成NOx排出量的減 少、引擎輸出的提升及燃料費的降低等。 另外，當異體凸輪33移動至避免與排氣側搖臂39之 抵接部39a接觸的位置時，排氣側搖臂39僅由排氣凸輪 3 1所驅動轉動，排氣汽門25是以對應於排氣凸輪3 1之凸 輪輪廓的作動態樣進行開閉動作。換言之，可藉由異體凸 輪33沿著凸輪軸32軸線的移動而切換：對應於排氣凸輪 3 1之凸輪輪廓的排氣汽門25的開閉作動態樣；及在對應 於排氣凸輪31之凸輪輪廓的開閉作動狀態下，形成「可 -14- 201013034 在於原本關閉汽門期間獲得暫時開啓汽門之狀態」的排氣 汽門25的作動態樣。 中心孔57是在前述凸輪軸32及前述從動鏈輪48設 成同軸，在凸輪軸32的其中一端部，同軸地螺鎖著用來 封閉酣述中心孔57之一端部的螺栓58。此外，在其中一 端部同軸地具有面向前述螺栓58之小徑軸部59Aa的桿 59A，是可在軸方向上移動且同軸地***前述中心孔57， φ 而桿59A的另一端是從前述從動鏈輪48突出。 此外，在配置有異體凸輪33的部分，是於前述凸輪 軸32設有「連結於前述中心孔57的内周面與前述凸輪軸 32的外周面間，且在前述凸輪軸32的軸方向上長距離延 伸」的導引孔60。而在該實施形態中，如第4圖所示，具 有垂直於前述中心孔57軸線C之軸線的一對導引孔60、 60，是被設於凸輪軸32，而可移動於軸方向且被安裝於凸 輪軸32外周的前述異體凸輪33及前述桿5 9A，是由單一 • 連結銷61所連結，該連結銷61可在貫穿前述導引孔60... 的狀態下，在導引孔60 ...内滑動於沿著前述軸線C的方向 上。 如此一來，異體凸輪33形成：在不會對凸輪軸32之 軸線周圍產生相對轉動的狀態下，可在「接近排氣凸輪3 1 並抵接於排氣側搖臂39之抵接部3 9a」的作動位置、及「 從排氣凸輪31分離，而避免抵接於排氣側搖臂39之抵接 部3 9 a」的非作動位置之間，移動於前述凸輪軸3 2的軸線 方向上，且被嵌裝於該凸輪軸32的外周。 -15- 201013034201013034 VI. Description of the Invention: [Technical Field] The present invention relates to a valve driving cam fixed to a cam shaft rotatably supported by a cylinder head, and having a cam profile different from the steam The door drives the cam of the cam, and switches between a state in which the valve driving member coupled to the engine valve is interlocked, a state in which the cam drive cam is driven, and "the slave valve driving member is driven from the foregoing Variable-actuating valve device for an engine in a state in which the cam shaft rotates together (previously-shaped cam) [Prior Art] Patent Document 1 discloses a variable-drive valve device of an engine in which a variable-drive valve device is integrated a camshaft provided with a valve driving cam is adjacent to the position of the valve driving cam, and a camshaft having a cam profile different from that of the valve driving cam is mounted so as not to be relatively rotatable, and can be switched φ "to make the cam and the camshaft and The state in which the valve is actuated by the cam is rotated, and "the cam is freely rotated with respect to the camshaft and the cam drive cam" State, and this technology has been known by the public. [Problem to be Solved by the Invention] However, in the variable drive valve device disclosed in Patent Document 1, it is possible to The relatively rotating lock pin 'fitting is fitted to the lock pin fitting portion of the foreign body cam disposed at -5 to 201013034, and the external cam is integrally rotated with the cam shaft and the valve drive cam, and the lock pin is fitted to the lock pin. A knocking sound is produced when the part is joined. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a variable drive valve device capable of suppressing an increase in size of a camshaft and suppressing an engine of knocking sound generation. [Means for Solving the Problem] In order to achieve the above object, the invention according to claim 1 is characterized in that a cam drive cam is fixed to a cam shaft that is rotatably supported by a cylinder head, and the cam profile is different from the steam. The door drives the cam of the cam, and is switchable: a state in which the valve driving member coupled to the engine valve is interlocked with the valve driving cam, and the valve driving member is driven together with the cam shaft a variable drive valve device of an engine that rotates the state of the aforementioned cam, characterized in that: the cam shaft is provided with: a center hole extending coaxially with the cam shaft; and an inner circumferential surface coupled to the center hole a guide hole extending between the outer peripheral surfaces of the cam shaft and extending a long distance in the axial direction of the cam shaft, and a rod that is movable in the axial direction and coaxially inserted into the center hole and movable in the axial direction The dissimilar cam attached to the outer circumference of the cam shaft is coupled by a coupling pin penetrating the guide hole in order to move the aforementioned valve driving member to the aforementioned valve Moving the cam between the non-actuated position in which the dissimilar cam is isolated from the valve driving cam, and the actuating position in which the dissimilar cam is brought close to the valve driving cam in order to cause the valve driving member to be driven by the dissimilar cam; -6-201013034 The rod driving means for driving the rod in the axial direction is the invention described in claim 2, characterized in that the first bearing and the second free are transmitted in addition to the structure of the invention described. The first bearing of the cam shaft rotatably supported by the cylinder head, the "intake cam for driving the intake valve opening and closing", and the aforementioned valve for driving the exhaust valve of the engine valve to open and close" It means an exhaust cam which is integrally provided with the intake cam disposed on the φ side; and is used for driving the exhaust valve to return a part of the discharged exhaust gas to the exhaust gas of the combustion chamber. The cam, that is, the aforementioned foreign body cam, is disposed between the front wheel and the second bearing. In addition to the structure of the invention described in claim 1, the camshaft-exhaust cam is the exhaust valve for driving the engine door opening and closing. a driving cam; and an intake cam for driving the intake valve to open and close; a portion for driving the exhaust gas discharged from the exhaust valve chamber to return to the combustion chamber recirculation cam, That is, the aforementioned foreign body cam is between the exhaust cam and the intake cam. The exhaust valve 25 of the embodiment corresponds to the door of the present invention, and the exhaust side rocker arm 39 of the embodiment corresponds to the movable member of the present invention, and the first ball bearing 44 of the embodiment corresponds to the first bearing. The second ball bearing 45 of the embodiment corresponds to the second bearing. The aforementioned rod. 'Request item 1 bearing and the second shaft and "used to drive the cam 1st bearing chamber" to recirculate the exhaust protrusion: except for the body: the exhaust gas cam is, and the combustion According to the invention of claim 1, the invention is the same as the invention described in the first aspect of the invention, and the "variable cam that can be moved in the axial direction and attached to the outer circumference of the camshaft" And a rod inserted "coaxially disposed in the center hole of the cam shaft" is inserted through the inner circumferential surface of the center hole and the outer peripheral surface of the cam shaft, and extends in the axial direction of the cam shaft for a long distance. The connection pin of the guide hole is connected, and the state in which "the valve drive member is driven by the valve drive cam" can be switched by the "simplified structure" of "driving the rod in the axial direction by the drive means", and The state in which the valve driving member is driven by the foreign body cam causes the camshaft to rotate normally with the camshaft, so that the generation of the knocking sound during the switching operation can be suppressed. Further, by accommodating the lever in the camshaft To avoid large-scale camshaft. According to the invention of claim 2, the first and second bearings of the "camshaft that is rotatably supported by the cylinder head through the first and second bearings" are used to drive the intake air. The intake cam of the valve opening and closing and the exhaust cam for "opening and closing the exhaust valve" are integrally formed by arranging the intake cam on the first bearing side, and are used as a cam for exhaust gas recirculation. The dissimilar cam is disposed between the exhaust cam and the second bearing, so that the dissimilar cam can be disposed in a state in which the cam shaft is well supported. Further, according to the invention of claim 3, the cam shaft is integrally provided with an exhaust cam for driving the exhaust valve to open and close, and an intake cam for driving the intake valve to open and close, and will serve as an exhaust. The variant cam of the gas recirculation cam is disposed between the exhaust cam and the intake cam, so that the space between the exhaust cam and the intake cam can be effectively utilized to configure the foreign body cam, and -8 - 201013034 avoids the cam according to the foreign body Embodiment in which the axial length of the camshaft is increased. [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 8 are views showing a first embodiment of the present invention, wherein Fig. 1 is a longitudinal sectional view of an important part of the engine, and Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1 of Fig. 1, Fig. 3 is an enlarged view of a portion indicated by an arrow 3 in Fig. 2, Fig. 4 is a cross-sectional view taken along line 4 - 4 of Fig. 3 in a state in which the decompression is stopped, and Fig. 5 is a view showing an intake steam FIG. 6 is an enlarged cross-sectional view showing the 6-6 line in the third diagram of the decompression stop state, and FIG. 7 is an exploded perspective view of the decompression device. Fig. 8 is a cross-sectional view corresponding to Fig. 6 in a state in which the decompression is activated. First, in the first and second figures, the engine body 11 of the engine is, for example, an engine body mounted on a locomotive, and the engine body 11 is provided with a Φ cylinder block 12 having a piston 15 freely slidable. a fitting cylinder bore 16; and a cylinder head 13 formed between the cylinder block 12 and the combustion chamber 17 facing the top of the piston 15 and coupled to the cylinder block 12; a head cover 14 that is coupled to the cylinder head 13 from the opposite side of the cylinder block 12; and a crankcase (not shown) that is coupled to the aforementioned side from the cylinder head 13 Cylinder block 12. The cylinder head 13 is provided with an intake port 18 having an opening formed on one side thereof, and an exhaust port 9 forming an opening on the other side of the cylinder head 13, -9-201013034 being formed to advance to the foregoing The intake pipe 21 of the intake passage 20 of the air cylinder 18 is connected to the cylinder head 13 described above, and a fuel injection valve 22 is attached to the intake pipe 21. Further, an intake valve 24 for switching the communication between the intake port 18 and the combustion chamber 17 and for interrupting; and for switching the communication between the exhaust port 19 and the combustion chamber 17 and blocking The exhaust valve 25' is detachably actuated to the cylinder head 13, and the intake valve 24 and the exhaust valve 25 are pushed by the valve springs 26, 27 toward the valve closing direction. Not only this, but also the spark plug 23 whose front end faces the combustion chamber 17 is attached to the cylinder head 13 described above. Referring to Fig. 3, the intake valve 24 and the exhaust valve 25 are variable drive steam accommodated in a "valve drive chamber 28 formed between the cylinder head 13 and the head cover 14". The door device 29A is driven to open and close. The variable drive valve device 29A is disposed between the intake valve 24 and the exhaust valve 25, and is provided with a cam shaft 32, and the cam shaft 32 is provided with an intake cam. 30 and the exhaust cam 31; and the foreign body cam 33, the cam profile of the foreign body @ cam 33 is different from the exhaust cam 31' and is movable in the axial direction on the outer circumference of the aforementioned camshaft 32 and is mounted so as not to be relatively rotatable; a decompression device 34A that holds the exhaust cam 31 between the cam and the camshaft 32 and is mounted on the camshaft 32; and an intake side and an exhaust side swing shaft 36, 37 'The intake side and exhaust side swing shafts 36, 37 have an axis 'parallel to the aforementioned cam shaft 32' and are supported by the cylinder head 14; and the intake side rocker arm 3 8 'the intake side rocker arm 3 8 It is driven by the aforementioned intake cam 30' and used to drive the intake and exhaust valve 24 to open and close 'and can -10- 20101303 4 is freely rocked by the intake side swing shaft 36; and the exhaust side rocker arm 39, the exhaust side rocker arm 39 is driven by the exhaust cam 31, the aforementioned foreign cam 33 or the aforementioned reduction The decompression cam 35 of the pressing device 34A is used to drive the exhaust valve 25 to open and close, and is rotatably supported by the exhaust side swing shaft 37. The cylinder head 13 is provided with a first support portion 42 having a first bearing hole 40 and a second support portion 43 having a first bearing hole 43 and a first bearing hole 40. The second bearing hole 41 is coaxial. One end portion of the cam shaft 32 is a first ball bearing 44 that is interposed between the first bearing and the inner circumference of the first bearing hole 40, and is rotatably supported by the first support portion 42. A portion of the cam shaft 32 near the other end is rotatably inserted through the second bearing hole 41, and a second ball bearing as a second bearing is interposed between the inner circumference of the second bearing hole 41 and the cam shaft 32. 45. The cam shaft 32 is an inner ring that is pressed into the first and second ball bearings 44 and 45. The intake cam 30 and the exhaust cam 31 are shaped like φ to arrange the intake cam 30 on the first ball bearing 44 side. The exhaust cam 31 is disposed on the second ball bearing 45 side, and is integrally formed between the first and second ball bearings 44 and 45 on the cam shaft 32, and the pressure reducing device 34A is disposed on the intake cam. Between the exhaust cam 31 and the exhaust cam 31, the foreign body cam 33 is attached to the cam shaft 32 at a position where the exhaust cam 31 is held between the pressure reducing cams 35 of the pressure reducing device 34A. The rotational force from the crankshaft not shown in the drawing is transmitted to the camshaft 32 via a timing transmission mechanism 47, which is an uninterrupted convex -11 - 201013034 The wheel chain 50 is wound around: a driven sprocket 48 fixed to a protruding end portion of the second ball bearing 45 from the cam shaft 32, and a drive sprocket fixed to the crank shaft (not in the drawing) The cam chain 50 is movably housed in the chain traveling path 51 formed over the cylinder block 12, the cylinder head 13, and the head cover 14. In the first drawing, the intake cam 30 and the exhaust cam 31 have arc-shaped base portions 30a and 31a which are defined by the axis of the cam shaft 32. a center portion; and a high portion 30b, 31b which protrudes outward from the base portion 30a, 31a and is connected between both ends of the base portion 30a, 31a in the circumferential direction; The cam 30 and the exhaust cam 31 are integrally formed on the cam shaft 32 by shifting the phases of the upper portions 30b and 31b. At one end portion of the intake side rocker arm 38 supported by the aforementioned intake side swing shaft 36 to be rockable, the shaft supports a roller 52' that is in rolling contact with the intake cam 30 at the other side of the intake side rocker arm 36 The tappet screw 53 that abuts against the shaft end 24a of the intake valve 24 at one end is screwed in an adjustable forward and backward position. Further, at one end portion of the intake side rocker arm 39 supported by the aforementioned intake side swing shaft 37 to be rockable, the shaft supports a roller 54' that is in rolling contact with the intake cam 31 at the intake side rocker arm 39. The other end portion of the tappet screw 55 that abuts against the shaft end 25a of the intake valve 25 is screwed in an adjustable forward and backward position. The width of the rollers 52, 54 along the axis of rotation is set to be larger than the width of the intake cam 30 and the exhaust cam 31 in the direction along the axis of the camshaft 32, and the rollers 52, 54 are in rolling contact. The above-described -12-201013034 intake cam 30 and the aforementioned exhaust cam 31 are at a central portion along the axial direction of the cam shaft 32. Further, the aforementioned rollers 52, 54 are configured such that a middle portion forms a stack in a viewing angle viewed from the axial direction of the cam shaft 32, and a specific interval is maintained between the rollers 52, 54 to avoid the roll 52, 54 interferes with each other, and the intake cam 30 and the exhaust cam 31' are also provided at the cam shaft 32 while maintaining an interval corresponding to the above-described interval. Further, at one end portion of the exhaust side rocker arm 39, φ abuts against the abutting portion 39a of the different-body cam 33 and the abutting portion 39b of the decompression cam 35 that can abut against the press device 34A, The roller 54 is held together to be integrally formed. The two abutting portions 39a and 39b are formed at least at the end on the side of the axle 3 2: from the direction along the axis of the camshaft 32, and the outer circumference of the roller 54. The aforementioned camshaft 3 2 side is more uniform or more prominent than the aforementioned outer circumference. The foreign body cam 33 can be moved close to the exhaust cam 31 and connected to the abutting portion 39a of the exhaust side rocker arm 39 (Fig. 3: a position indicated by a solid line), and from the exhaust cam 31 is separated from the non-actuated position abutting the abutting portion 39a of the exhaust side rocker arm 39, and the position indicated by a broken line in Fig. 3, is moved in the axial direction of the cam shaft, and is in the cam The outer circumference of the shaft 32 is fitted so as not to be rotatable around the axis of the axle 32. Referring to Fig. 4, the aforementioned foreign body cam 33 is a discharge gas recirculation cam for driving the front exhaust valve 25 to open the valve, and a part of the exhaust gas discharged from the combustion chamber 17 can be returned. The combustion chamber 17 has a circular arc-shaped base circle having the axis of the cam shaft 32 as a center, and the weight of the base of the arc-shaped base circle is reduced by the convexity of the protrusion (32 embossed by its part-13-201013034 33a, and The base portion 33a of the variant cam 33 is formed to have a smaller outer diameter than the base portion 31a of the exhaust cam 31. The upper portion 33b is corresponding to the upper portion 33b of the outer cam 33. In the portion of the intake cam 30 that closes the end of the valve in the upper portion 30b, a portion slightly protruding from the base portion 33a, the both ends of the upper portion 33b in the circumferential direction form a smooth curve and are connected to the base portion 33a. When the foreign body cam 33 moves to the actuating position of "abutting against the abutting portion 39a of the exhaust side rocker arm 39", the exhaust side rocker arm 39 is caused to rotate by the rotation of the upper portion 31b of the exhaust cam 31. After the gas valve 25 performs the action of closing the valve, it is abutted by The base portion 31a of the exhaust cam 31 maintains the state in which the valve is closed, but the intake valve 24 is at the end of the operation of closing the valve, as shown in Fig. 5, and is arranged by the upper portion 33b of the foreign body cam 33. The gas side rocker arm 39 produces a slight rotation to cause the exhaust valve 25 to slightly open the valve. Thus, the exhaust valve 25 can be temporarily opened during the compression stroke, and the exhaust gas is caused to be in the combustion chamber by the exhaust gas. The activation of the combustion in 1 7 can achieve a reduction in the amount of NOx emission, an increase in engine output, a decrease in fuel cost, etc. Further, when the foreign body cam 33 is moved to avoid contact with the abutment portion 39a of the exhaust side rocker arm 39 In the position of the exhaust side, the exhaust side rocker arm 39 is only driven to rotate by the exhaust cam 31, and the exhaust valve 25 is opened and closed in a dynamic manner corresponding to the cam profile of the exhaust cam 31. In other words, it can be borrowed. Switching by the movement of the foreign body cam 33 along the axis of the camshaft 32: opening and closing of the exhaust valve 25 corresponding to the cam profile of the exhaust cam 3 1 as a dynamic sample; and opening and closing of the cam profile corresponding to the exhaust cam 31 In the state of being activated, the formation of "Can-14 - 201013 034 is a dynamic example of the exhaust valve 25 in a state in which the valve is temporarily opened during the closing of the valve. The center hole 57 is coaxially disposed on the cam shaft 32 and the driven sprocket 48, and the cam shaft 32 is provided. One end portion thereof is coaxially screwed with a bolt 58 for closing one end portion of the center hole 57. Further, a rod 59A having a one end portion coaxially facing the small diameter shaft portion 59Aa of the bolt 58 is coaxially Moving in the axial direction and coaxially inserting the center hole 57, φ and the other end of the rod 59A protrudes from the driven sprocket 48. Further, in the portion where the foreign body cam 33 is disposed, the cam shaft 32 is provided. A guide hole 60 that is connected between the inner circumferential surface of the center hole 57 and the outer circumferential surface of the cam shaft 32 and extends long in the axial direction of the cam shaft 32. In this embodiment, as shown in Fig. 4, a pair of guide holes 60, 60 having an axis perpendicular to the axis C of the center hole 57 are provided on the cam shaft 32 and are movable in the axial direction. The foreign body cam 33 and the rod 5 9A attached to the outer circumference of the cam shaft 32 are connected by a single coupling pin 61 which can be guided through the guide hole 60... The hole 60 ... is slid inside the direction along the aforementioned axis C. In this way, the foreign body cam 33 is formed to "close to the exhaust cam 3 1 and abut against the abutting portion 3 of the exhaust side rocker arm 39 in a state where the relative rotation around the axis of the cam shaft 32 is not caused. The operating position of 9a" and the "actuated position separated from the exhaust cam 31 to avoid abutting against the abutting portion 39 a of the exhaust side rocker arm 39" are moved between the axes of the cam shaft 32 In the direction, it is fitted to the outer circumference of the cam shaft 32. -15- 201013034
在前述桿59A與前述螺栓58間縮設有線圈狀的回動 彈賛（return spring) 62，該線圈狀的回動彈簧.（return spring) 62圍繞著前述桿59A的小徑軸部59Aa，桿59A 則是被前述回動彈簧62彈推至「使前述異體凸輪33成爲 非作動位置」的那一側。 前述桿59A，是可促使前述異體凸輪33在非作動位 置與作動位置之間移動，並由桿驅動手段63朝軸方向驅 動的構件，該桿驅動手段63具備：電磁閥64，該電磁閥 64是由複數支螺栓68、68...安裝於汽缸頭13的側壁；及 轉動撥桿67，該轉動撥桿67的基端部是透過支軸66而可 自由轉動地由前述汽缸頭13所支承，且前端部抵接於前 述桿59 A的另一端，前述電磁閥64所具備之輸出軸65的 前端，具有與前述凸輪軸32平行的軸線，且從前桿5 9A 的相反側抵接於前述轉動撥桿67。 根據上述的桿驅動手段63，當電磁閥64作動至使輸 出軸65突出的那一側時，轉動撥桿67將克服回動彈簧62 的彈簧力而朝第2圖及第4圖的順時針方向轉動，並克服 回動彈簧62的彈簧力後將桿59A壓入，使得異體凸輪33 移動至「接近排氣凸輪31，且抵接於排氣側搖臂39之抵 接部39a」的作動位置，在電磁閥64的非作動狀態下，異 體凸輪33是藉由回動彈簧62的彈簧力，而移動至「從排 氣凸輪31分離’而避免抵接於排氣側搖臂39之抵接部 3 9a」的非作動位置。 —倂參考第6圖及第7圖，減壓裝置34A，是爲了降 201013034 低引擎啓動時的排氣壓力以便於容易啓動，而在引擎旋轉 數、也就是指凸輪軸32的旋轉數較低的狀態下，促使排 氣汽門2 5在原本關閉的時間點些微地開啓汽門的裝置’ 該減壓裝置3 4A具備：減壓配重72，該減壓配重72是透 過具有與凸輪軸32平行之軸線的減壓銷7〗A，而可轉動 地由進氣凸輪30與排氣凸輪31所支承；及減壓凸輪35, 該減壓凸輪35是在低引擎旋轉數的狀態下，從排氣凸輪 φ 31的基圓部31a突出，並藉由隨著「抵接於排氣側搖臂 39之抵接部39b的凸輪軸32朝第6圖的箭號73所指示的 方向旋轉」所產生的離心力作用，在減壓配重72轉動時 不會抵接於前述排氣側搖臂39的抵接部39b，且連結於減 壓配重72，該減壓裝置34 A被配置於進氣凸輪30與排氣 凸輪31之間，且由進氣凸輪30與排氣凸輪31所支承。 減壓配重72，是從側方覆蓋凸輪軸32的略半周而形 成圓弧狀，且其中一面的局部滑接於凸輪軸32的進氣凸 • 輪30，並被配置於進氣凸輪30與排氣凸輪31之間，該減 壓配重72的其中一端，是被配置成對應於前述凸輪軸32 之排氣凸輪31的高位部31b。不僅如此，在減壓配重72 的其中一端部面對前述排氣凸輪31之那一側的面上，設 有朝排氣凸輪3 1側開放的圓形收容凹部74，在該收容凹 部74嵌合著圓筒狀支承突座75的其中一端部。此外’在 支承突座75的另一端，突出於半徑方向外側的鍔部75a’ 是與支承突座75的另一端面連接成同一平面地設成一體 ，支承突座75的另一端是抵接於前述凸輪軸32之排氣凸 -17- 201013034 輪3 1的高位部3 1 b。 前述減壓銷71A，是從進氣凸輪30側貫穿該進氣凸 輪30、減壓配重72、前述支承突座75及前述排氣凸輪31 ，在進氣凸輪30設有可供前述減壓銷71A貫穿的第1貫 穿孔76,在前述減壓配重72的其中一端部，可供前述減 壓銷71A貫穿的第2貫穿孔77是同軸地連通於前述收容 凹部74而設置，在前述排氣凸輪31的高位部31b，可供 前述減壓銷71A***的盲孔78是被設成：與前述第1及 第2貫穿孔76、77同軸，且朝前述進氣凸輪30側開放。 而減壓銷71A，是從進氣凸輪30側貫穿該進氣凸輪 30的第1貫穿孔76、減壓配重72的第2貫穿孔77、支承 突座75與排氣凸輪31的貫穿孔78，如此一來，減壓配重 72的其中一端部，是透過被進氣凸輪30與排氣凸輪31雙 方所支承的減壓銷71A，而可轉動地被進氣凸輪30與排 氣凸輪3 1所支承。 不僅如此，在其中一端部抵接於前述貫穿孔78之閉 塞端的前述減壓銷71A的另一端，是藉由抵接於墊圈79 的外周部，而阻止從減壓銷71A的前述第1貫穿孔76、 第2貫穿孔77、支承突座75與貫穿孔78離脫。換言之， 內周部被挾持於「可將前述第1滾珠軸承44與進氣凸輪 30間的間隔保持一定的第1滾珠軸承44的内輪44a與凸 輪軸32間」之墊圈79的外周部，是抵接於進氣凸輪30, 故可以不需要「使該墊圈79的外周抵接於前述減壓銷 71A的另一端，用來決定減壓銷71A之軸方向位置」的專 -18- 201013034 用構件。 此外，圍繞著前述支承突座75之線圈狀扭力彈簧80 的其中一端部，是卡合於設在前述凸輪軸32的有底卡合 孔81，而扭力彈簧80的另一端部，是卡合在設於前述減 壓配重72之其中一端部的卡合孔82。藉由該扭力彈簧80 的彈簧力，而將減壓配重72彈推至：使該減壓配重72的 中間部接近凸輪軸3 2外周面的那一側。 @ 前述減壓凸輪35，是在對應於排氣凸輪31之基圓部 31a的位置，被配置於前述減壓配重72的另一端側與前述 排氣凸輪31之間的構件，且可轉動地由植設於前述排氣 凸輪31的減壓凸輪軸84所支承。而減壓凸輪軸84，是具 有與凸輪軸32的軸線平行之軸線的構件，減壓凸輪35可 在與凸輪軸32之軸線平行的軸線周圍轉動，且被凸輪軸 3 2所支承。 雖然前述減壓凸輪35，基本上是形成與前述減壓凸輪 φ 軸84同軸的圓柱狀，但該減壓凸輪35之前述排氣凸輪31 側的局部，是被切割而形成與減壓凸輪35之軸線平行的 平面部85。換言之，減壓凸輪35之排氣凸輪31側的外周 是形成由以下構件所構成：將減壓凸輪軸84的軸線作爲 中心的圓弧部86、及連結於該圓弧部86的周方向兩端間 的前述平面部8 5，該減壓凸輪3 5可在以下的兩種狀態間 轉動：如第6圖所示，使較前述排氣凸輪31的基圓部31a 位於更内側的前述平面部8 5面向外側的減壓停止狀態； 及如第8圖所示，使前述圓弧部86的一部分較前述排氣 -19- 201013034 凸輪3 1的基圓部3 1 a更突出於外側的減壓啓動狀態。 而當減壓凸輪35的圓弧部86從前述基圓部31a朝外 側突出時，藉由使排氣側搖臂39的抵接部39b抵接於圓 弧部86，可使排氣側搖臂39轉動，而促使排氣汽門25些 微地開啓汽門。 在前述減壓配重72的另一端部，壓入著「具有與凸 輪軸32平行之軸線」的連結銷87，可供「來自於該連結 銷87之減壓配重72的突出部」嵌合的導引溝88，是沿著 減壓凸輪35的半徑方向延伸，而設於該減壓凸輪35之減 壓配重72側的部分。由於凸輪軸32的旋轉數較大而使作 用於減壓配重72的離心力較大，在減壓配重72反抗前述 扭力彈簧80的彈推力而轉動並促使該減壓配重72的中間 部從凸輪軸32的外周分離的減壓停止狀態中，如第6圖 所示，嵌合於導引溝88的連結銷87與減壓配重72 —起 轉動，在狀態下的減壓凸輪35，該平面部85是位在：在 較前述排氣凸輪31的基圓部31a更內側，且面臨外側的 轉動位置，排氣側搖臂39的抵接部39b並不會抵接於減 壓凸輪35，且排氣側搖臂39追隨著排氣凸輪31的凸輪輪 廓而搖動，排氣汽門25也追隨著排氣凸輪31之凸輪輪廓 的時間點進行開閉作動。此外，由於凸輪軸32的旋轉數 較小而使作用於減壓配重72的離心力較小，在減壓配重 72藉由前述扭力彈簧80的彈推力而轉動並促使該減壓配 重72的中間部接近凸輪軸32外周的減壓啓動狀態中，如 第8圖所示，嵌合於導引溝88的連結銷87是與減壓凸輪 -20- 201013034 35 —起轉動，該狀態下的減壓凸輪35’該圓弧部86的一 部分是位在：從前述排氣凸輪3 1的基圓部3 1 a朝外側突 出的轉動位置，由於排氣側搖臂39的抵接部39b抵接於 減壓凸輪35的圓弧部86，因此排氣側搖臂39在滾子54 接觸於排氣凸輪31之基圓部31a的時間點，藉由前述減 壓凸輪35而略爲搖動’排氣汽門25是形成：無視於排氣 凸輪3 1的凸輪輪廓，而在關閉汽門的時間點些微地開啓 φ 汽門。 除此之外，在減壓停止時，排氣汽門25開啓汽門的 時間點，是如第5圖所示，被設定在：在由異體凸輪33 促使排氣汽門25開啓汽門之時間點的附近，且從該時間 點略爲偏移的相位。 接著、說明該第1實施形態的作用，由於凸輪輪廓不 同於排氣凸輪31的異體凸輪33可切換：使排氣側搖臂39 從動於排氣凸輪31的狀態、及使與凸輪軸32 —起旋轉的 • 異體凸輪3 3從動於前述排氣側搖臂3 9的狀態，且是在排 氣凸輪31被挾持於與減壓凸輪35之間的位置，被安裝於 凸輪軸32’因此可一起使用減壓裝置3 4A與異體凸輪33 而促使排氣汽門25的汽門驅動特性有多樣的變化，且能 使可變驅動汽門裝置29A構成小型化。 此外，由於在透過第1與第2滾珠軸承44、45而可 自由旋轉地支承於汽缸頭13的前述凸輪軸32，設有被配 置於第1與第2滾珠軸承44、45之間的進氣凸輪30及排 氣凸輪31，且減壓裝置34A被配置於進氣凸輪30與排氣 -21 - 201013034 凸輪31之間，故能有效地利用進氣凸輪30與排氣凸輪31 間的空間來配置減壓裝置34 A，並可藉由減壓裝置34 A的 配置而避免凸輪軸32之軸長度增加。 除此之外，由於減壓裝置3 4A是被進氣凸輪30與排 氣凸輪31所支承，因此能以兩端支承的構造穩定地支承 減壓裝置34A。 不僅如此，由於在前述凸輪軸3 2設有：中心孔5 7， 該中心孔5 7是與凸輪軸3 2同軸地延伸；及導引孔60，該 ⑩ 導引孔60連結於中心孔57的内周面與凸輪軸32的外周 面間，且在凸輪軸32的軸方向上長距離延伸，而「可移 動於軸方向上，且同軸地***中心孔57内」的桿59A、 及「可移動於軸方向上且被安裝於凸輪軸32外周」的異 體凸輪33，是由貫穿導引孔60的連結銷61所連結；在「 能使排氣側搖臂39從動於排氣凸輪31的異體凸輪33，從 排氣凸輪3 1隔離」的非作動位置、與「能使排氣側搖臂 39從動於異體凸輪33的異體凸輪33，接近排氣凸輪31」 ◎ 的作動位置之間，於軸方向上驅動桿59A的桿驅動手段 63是連結於桿59A，因此，能以「利用桿驅動手段63在 軸方向上驅動桿59 A」的簡易構造，來切換「使排氣側搖 臂39從動於排氣凸輪3 1」的狀態、以及「使排氣側搖臂 39從動於異體凸輪33」的狀態，由於異體凸輪33通常是 與凸輪軸32 —起旋轉，故能抑制切換作動時之敲擊聲的 產生，此外，可藉由將桿59A收容於凸輪軸32内，避免 凸輪軸3 2的大型化。 -22- 25 201013034 此外，由於異體凸輪33，用來驅動前述排氣汽門 ，而使燃燒室17所排出之排放氣體的一部份回到燃燒 17的排放氣體再循環用凸輪，且該異體凸輪33是被配 在排氣凸輪31與第2軸承45之間，因此凸輪軸32是 由進氣凸輪30與排氣凸輪31兩側的第1及第2滾珠軸 44、45而可自由旋轉地支承於汽缸頭，藉此既能良好地 凸輪軸32軸支承，又能配置異體凸輪32。 φ 第9圖是顯示本發明的第2實施形態，爲對應於第 實施例之第3圖的剖面圖。 而對應於第1實施形態的部分僅標示相同的參考圖 來表示，並省略其詳細的說明。 進氣汽門24與排氣汽門25，是由「被收容在形成 汽缸頭13與頭蓋14之間的汽門驅動室28」的可變驅動 門裝置29B所開閉驅動，該可變驅動汽門裝置29B具備 凸輪軸32，該凸輪軸32被配置在前述進氣汽門24與排 φ 汽門25之間，並且設有進氣凸輪30與排氣凸輪31;和 體凸輪33，該異體凸輪33的凸輪輪廓不同於排氣凸輪 ，並可移動移軸方向且不能相對旋轉地安裝於前述凸輪 32的外周；和減壓裝置34B，該減壓裝置34B是被安裝 前述凸輪軸32，而使前述排氣凸輪31被挾持於其與前 異體凸輪3 3之間；和進氣側與排氣側擺動軸3 6、3 7， 進氣側與排氣側擺動軸36、37是被支承於汽缸頭14而 有與前述凸輪軸3 2平行的軸線；和進氣側搖臂3 8，該 氣側搖臂3 8是可自由搖動地支承於進氣側擺動軸3 6， 室 置 藉 承 對 號 於 汽 氣 異 3 1 軸 於 述 該 具 進 而 -23- 201013034 從動於前述進氣凸輪30，並驅動進氣汽門24;及排氣 搖臂39,該排氣側搖臂39是可自由搖動地支承於排氣 擺動軸37，而從動於具有前述排氣凸輪31、前述異體 輪33或前述減壓裝置34B的減壓凸輪35，並驅動排氣 門25開閉。 進氣凸輪30與排氣凸輪31，是在第1與第2滾珠 承44、45之間一體形成於凸輪軸32，而將進氣凸輪30 置於第1滾珠軸承44側，並將排氣凸輪31配置於第2 珠軸承45側，異體凸輪33是在進氣凸輪30與排氣凸 31之間，嵌裝於前述凸輪軸32的外周，前述減壓裝 3 4B是在排氣凸輪31與第2滾珠軸承45之間安裝於凸 軸32。 前述異體凸輪33是在凸輪軸32的外周嵌裝成：可 「接近前述排氣凸輪31且抵接於排氣側搖臂39之抵接 39b」的作動位置（第9圖中以實線表示的位置）、與 從前述排氣凸輪31分離而避免抵接於前述排氣側搖臂 之抵接部39b」的非作動位置（第9圖中以虛線表示的 置）之間’移動於前述凸輪軸32的軸線方向，並無法 該凸輪軸32的軸線周圍相對轉動。 「於其中一端部同軸地具有面向螺栓58之小徑軸 59Ba」的桿59B，是可移動於軸線方向且同軸地***前 凸輪軸32的中心孔57，在桿59B與螺栓58間縮設有 動彈簧62’在桿59B的另一端連結有：於軸方向上驅 該桿59B的桿驅動手段63。 側 側 凸 汽 軸 配 滾 輪 置 輪 在 部 厂 39 位 在 部 述 回 動 201013034 在凸輪軸32設有：連結於中心孔57的内周面與凸輪 軸32的外周面之間，且在凸輪軸32的軸方向上長距離延 伸的導引孔60，可移動於軸方向地安裝於凸輪軸32外周 的異體凸輪33與前述桿59B，是由貫穿前述導引孔60的 單一連結銷6 1所連結。 而當前述桿驅動手段63作動成「其轉動撥桿67克服 回動彈簧62的彈簧力而朝第9圖的順時針方向轉動」時 φ ，異體凸輪33是從排氣凸輪31分離而形成非作動位置， 此外當轉動撥桿67作動成「藉由回動彈簧62的彈簧力而 朝第9圖的逆時針方向轉動」時，異體凸輪33是接近排 氣凸輪31而移動至抵接於排氣側搖臂39之抵接部39b的 作動位置。 減壓裝置34B具備：減壓配重72，該減壓配重72是 透過具有與凸輪軸32平行之軸線的減壓銷71B，而可轉 動地支承於進氣凸輪30與排氣凸輪31;及減壓凸輪35, φ 該減壓凸輪35是連結於減重配重72，而可藉由隨著「在 引擎旋轉數低的狀態下，從排氣凸輪31的基圓部31a突 出，並抵接於排氣側搖臂39之抵接部39a的凸輪軸32的 旋轉」所產生之離心力的作用，當減壓配重72轉動時不 會抵接於前述排氣側搖臂39的抵接部39a;減壓裝置34B 被配置於排氣凸輪31與第2滾珠軸承45之間，並由進氣 凸輪30與排氣凸輪31所支承。 減壓配重72是形成圓弧狀，而從側方覆蓋凸輪軸32 的略半周’並且被配置於階梯部32a與前述排氣凸輪31 -25- 201013034 之間，而使局部滑接於「面向第2滾珠軸承45的相反側 ，並形成於前述凸輪軸32」的該階梯部3 2a，且在該減壓 配重72的其中一端、與位於前述凸輪軸32之排氣凸輪31 的高位部31b之間，夾設有圓筒狀的支承突座75。 前述減壓銷71B，是從進氣凸輪30側貫穿該進氣凸 輪30、前述排氣凸輪31、前述支承突座75及前述減壓配 重72的構件，減壓銷71B的軸方向移動，是由前述凸輪 軸32的階梯部32a、及「內周部被挾持於第1滾珠軸承 44的内輪44a與凸輪軸32間」之墊圈79的外周部所阻止 〇 此外，圍繞著前述支承突座75的線圈狀扭力彈簧80 ，是被設於減壓配重72與凸輪軸32間，減壓配重72是 將該減壓配重72的中間部，彈推至接近凸輪軸32外周面 的那一側。 前述減壓凸輪35，是由「具有平行於凸輪軸32之軸 線的軸線，且被植設於排氣凸輪31」的減壓凸輪軸84支 承成可轉動，減壓凸輪35是被凸輪軸32所支承，而可以 在平行於凸輪軸32之軸線的軸線周圍轉動。 該減壓裝置34B，與第1實施例相同，在凸輪軸32 的旋轉數較大的減壓停止狀態下，減壓凸輪35不會抵接 於排氣側搖臂39的抵接部39a，排氣側搖臂39是追隨著 排氣凸輪31的凸輪輪廓而搖動，排氣汽門25也在追隨於 排氣凸輪3 1之凸輪輪廓的時間點開閉作動。此外，在凸 輪軸3 2的旋轉數較小的減壓啓動狀態下，由於排氣側搖 -26- 201013034 臂39的抵接部39a抵接於減壓凸輪35的圓弧部86’因此 排氣側搖臂39是在「滾子54接觸於排氣凸輪31之基圓 部31a」的時間點’藉由前述減壓凸輪35而形成些微的搖 動，排氣汽門25也形成：無關於排氣凸輪31的凸輪輪廓 ，而在關閉汽門的時間點開啓汽門。 根據該第2實施形態’由於作爲排放氣體再循環用凸 輪的異體凸輪33’被配置在排氣凸輪31與進氣凸輪30之 間，因此能有效地利用排氣凸輪3 1與進氣凸輪3 0間的空 間來配置異體凸輪33，且能藉由異體凸輪33的配置而避 免凸輪軸32之軸長度的增加。 以上雖然是針對本發明的實施例所作的說明，但本發 明並不侷限於上述實施例，只要不逸脫申請專利範圍所記 載之本發明的範圍，是能有各種設計變更的可能》 【圖式簡單說明】 第1圖：是顯示第1實施形態，爲引擎之重要部分的 縱剖面圖。 第2圖：爲第1圖中2— 2線的剖面圖。 第3圖：爲第2圖中箭號3所指部份的放大圖。 第4圖：爲減壓停止狀態下之第3圖的4 - 4線剖面 圖。 第5圖：是顯示進氣汽門與排氣汽門之開啓汽門揚程 特性的圖。 第6圖：爲減壓停止狀態下之第3圖的6_6線放大 -27- 201013034 剖面圖。 第7圖：爲減壓裝置的分解立體圖。 第8圖：是對應於減壓啓動狀態下之第6圖的剖面圖 〇 第9圖：是顯示第2實施形態，爲對應於第3圖的剖 面圖。 【主要元件符號說明】 @ 1 3 :汽缸頭 1 7 :燃燒室 24 :進氣汽門 25 :作爲引擎汽門的排氣汽門 29A、29B :可變驅動汽門裝置 30 :進氣凸輪 3 1 :作爲汽門驅動凸輪的排氣凸輪 32 :凸輪軸 ❿ 33 :異體凸輪 3 9 :作爲汽門驅動構件的排氣側搖臂 44:作爲第1軸承的第1滾珠軸承 45:作爲第2軸承的第2滾珠軸承 5 7 :中心孔 59 :桿 60 :導引孔 61 :連結銷 -28- 201013034 63 :桿驅動手段A coil-shaped return spring 62 is retracted between the rod 59A and the bolt 58. The coil-shaped return spring 62 surrounds the small-diameter shaft portion 59Aa of the rod 59A. In the case of 59A, the return spring 62 is pushed to the side where "the above-described foreign body cam 33 is in the non-actuated position". The rod 59A is a member that urges the foreign body cam 33 to move between the non-actuated position and the actuating position, and is driven in the axial direction by the rod driving means 63. The rod driving means 63 is provided with a solenoid valve 64. The solenoid valve 64 is provided. It is mounted on the side wall of the cylinder head 13 by a plurality of bolts 68, 68... and a rotary lever 67. The base end portion of the rotary lever 67 is rotatably driven by the cylinder head 13 through the support shaft 66. The front end portion abuts against the other end of the rod 59 A, and the distal end of the output shaft 65 of the electromagnetic valve 64 has an axis parallel to the cam shaft 32 and abuts against the opposite side of the front rod 5 9A The aforementioned turning lever 67 is rotated. According to the above-described lever driving means 63, when the solenoid valve 64 is actuated to the side where the output shaft 65 protrudes, the rotary lever 67 will overcome the spring force of the return spring 62 toward the clockwise of Figs. 2 and 4. When the direction is rotated and the spring force of the return spring 62 is overcome, the rod 59A is pushed in, so that the foreign body cam 33 is moved to the "close to the exhaust cam 31 and abuts against the abutment portion 39a of the exhaust side rocker arm 39". At the position, in the non-actuated state of the solenoid valve 64, the foreign body cam 33 is moved to "separate from the exhaust cam 31" by the spring force of the return spring 62 to avoid abutment against the exhaust side rocker arm 39. The non-actuated position of the joint portion 3 9a". - Referring to Figures 6 and 7, the pressure reducing device 34A is for lowering the exhaust pressure at the start of the 201013034 low engine to facilitate easy starting, and the number of engine revolutions, that is, the number of rotations of the cam shaft 32 is low. In a state in which the exhaust valve 25 is slightly opened at a time when the exhaust valve 25 is closed, the decompression device 34A is provided with a decompression weight 72 that is transmitted through the cam and the cam. The decompression pin 7 A of the axis parallel to the axis 32 is rotatably supported by the intake cam 30 and the exhaust cam 31; and the decompression cam 35 is in a state of low engine rotation number Extending from the base circular portion 31a of the exhaust cam φ 31, by the direction indicated by the arrow 73 of Fig. 6 with the cam shaft 32 abutting against the abutting portion 39b of the exhaust side rocker arm 39 The centrifugal force generated by the rotation does not abut against the abutting portion 39b of the exhaust side rocker arm 39 when the decompression weight 72 rotates, and is coupled to the decompression weight 72, and the decompression device 34A is It is disposed between the intake cam 30 and the exhaust cam 31, and is supported by the intake cam 30 and the exhaust cam 31. The decompression weight 72 is formed in an arc shape by covering a slight half of the cam shaft 32 from the side, and one of the surfaces is partially slidably coupled to the intake cam wheel 30 of the cam shaft 32, and is disposed on the intake cam 30. Between the exhaust cam 31 and the exhaust cam 31, one end of the decompression weight 72 is a high portion 31b that is disposed to correspond to the exhaust cam 31 of the cam shaft 32. Further, on a surface of the one end portion of the decompression weight 72 facing the exhaust cam 31, a circular housing recess 74 that opens toward the exhaust cam 31 side is provided, and the housing recess 74 is provided in the receiving recess 74. One end portion of the cylindrical support protrusion 75 is fitted. Further, at the other end of the support projection 75, the flange portion 75a' projecting outward in the radial direction is integrally formed in the same plane as the other end surface of the support projection 75, and the other end of the support projection 75 is abutted. The upper portion 3 1 b of the wheel 3 1 of the exhaust cam -17- 201013034 of the camshaft 32 described above. The decompression pin 71A penetrates the intake cam 30, the decompression weight 72, the support protrusion 75, and the exhaust cam 31 from the intake cam 30 side, and the intake cam 30 is provided with the decompression. The first through hole 76 through which the pin 71A is inserted is provided at one end portion of the decompression weight 72, and the second through hole 77 through which the decompression pin 71A can pass is coaxially communicated with the housing recess 74. The upper portion 31b of the exhaust cam 31 is provided with a blind hole 78 into which the decompression pin 71A is inserted, and is coaxial with the first and second through holes 76 and 77, and is open toward the intake cam 30 side. The decompression pin 71A is a first through hole 76 that penetrates the intake cam 30 from the intake cam 30 side, a second through hole 77 that decompresses the weight 72, and a through hole that supports the protrusion 75 and the exhaust cam 31. 78. In this way, one end portion of the decompression weight 72 is rotatably received by the intake cam 30 and the exhaust cam through the decompression pin 71A supported by both the intake cam 30 and the exhaust cam 31. 3 1 support. Further, the other end of the decompression pin 71A at which one end portion abuts against the closing end of the through hole 78 is prevented from abutting from the outer peripheral portion of the washer 79 by the first through portion of the decompression pin 71A. The hole 76, the second through hole 77, and the support protrusion 75 are separated from the through hole 78. In other words, the inner peripheral portion is held by the outer peripheral portion of the washer 79 between the inner wheel 44a and the cam shaft 32 of the first ball bearing 44 that can maintain a constant interval between the first ball bearing 44 and the intake cam 30. Since the intake cam 30 is in contact with the intake cam 30, it is not necessary to "close the outer circumference of the washer 79 to the other end of the decompression pin 71A and determine the axial position of the decompression pin 71A". member. Further, one end portion of the coil-shaped torsion spring 80 surrounding the support protrusion 75 is engaged with the bottomed engagement hole 81 provided in the cam shaft 32, and the other end portion of the torsion spring 80 is engaged. An engaging hole 82 provided at one end portion of the pressure reducing weight 72 is provided. By the spring force of the torsion spring 80, the decompression weight 72 is pushed until the intermediate portion of the decompression weight 72 approaches the outer circumferential surface of the cam shaft 32. The decompression cam 35 is a member disposed between the other end side of the decompression weight 72 and the exhaust cam 31 at a position corresponding to the base circular portion 31a of the exhaust cam 31, and is rotatable The ground is supported by a decompression camshaft 84 that is implanted in the exhaust cam 31. The decompression camshaft 84 is a member having an axis parallel to the axis of the camshaft 32. The decompression cam 35 is rotatable about an axis parallel to the axis of the camshaft 32 and is supported by the camshaft 32. Although the decompression cam 35 basically has a cylindrical shape coaxial with the decompression cam φ axis 84, a portion of the decompression cam 35 on the side of the exhaust cam 31 is cut and formed with the decompression cam 35. A flat portion 85 whose axes are parallel. In other words, the outer circumference of the decompression cam 35 on the side of the exhaust cam 31 is formed by a circular arc portion 86 having the axis of the decompression camshaft 84 as a center, and two circumferential directions connected to the arcuate portion 86. The flat portion 85 of the end between the ends, the decompression cam 35 can be rotated between the two states: as shown in Fig. 6, the base portion 31a of the exhaust cam 31 is located on the inner side of the plane a portion 8 5 facing the outside of the decompression stop state; and as shown in Fig. 8, a part of the arc portion 86 is protruded from the base portion 3 1 a of the exhaust -19 - 201013034 cam 3 1 Decompression start state. When the arc portion 86 of the decompression cam 35 protrudes outward from the base portion 31a, the exhaust portion can be shaken by abutting the abutting portion 39b of the exhaust side rocker arm 39 against the arc portion 86. The arm 39 rotates to cause the exhaust valve 25 to slightly open the valve. At the other end of the decompression weight 72, a coupling pin 87 "having an axis parallel to the cam shaft 32" is press-fitted, and the "protrusion from the decompression weight 72 of the coupling pin 87" is embedded. The guide groove 88 is a portion extending along the radial direction of the decompression cam 35 and provided on the decompression weight 72 side of the decompression cam 35. Since the centrifugal force of the decompression weight 72 is large due to the large number of rotations of the cam shaft 32, the decompression weight 72 rotates against the spring force of the torsion spring 80 to urge the intermediate portion of the decompression weight 72. In the decompression stop state separated from the outer circumference of the cam shaft 32, as shown in Fig. 6, the coupling pin 87 fitted to the guide groove 88 rotates together with the decompression weight 72, and the decompression cam 35 in the state. The flat portion 85 is located on the inner side of the base circular portion 31a of the exhaust cam 31 and faces the outer rotational position, and the abutting portion 39b of the exhaust side rocker arm 39 does not abut against the decompression. The cam 35 and the exhaust side rocker arm 39 are swung in accordance with the cam profile of the exhaust cam 31, and the exhaust valve 25 also opens and closes at the time of following the cam profile of the exhaust cam 31. Further, since the centrifugal force acting on the decompression weight 72 is small due to the small number of rotations of the cam shaft 32, the decompression weight 72 is rotated by the spring force of the torsion spring 80 and urges the decompression weight 72. In the decompression starting state in which the intermediate portion is close to the outer circumference of the cam shaft 32, as shown in Fig. 8, the coupling pin 87 fitted to the guide groove 88 is rotated together with the decompression cam -20-201013034 35. A part of the circular arc portion 86 of the decompression cam 35' is located at a rotational position that protrudes outward from the base circle portion 31a of the exhaust cam 31, and the abutment portion 39b of the exhaust side rocker arm 39 Abutting against the arc portion 86 of the decompression cam 35, the exhaust side rocker arm 39 is slightly shaken by the decompression cam 35 at the time point when the roller 54 contacts the base circle portion 31a of the exhaust cam 31. The exhaust valve 25 is formed: the cam profile of the exhaust cam 3 1 is ignored, and the φ valve is slightly opened at the time of closing the valve. In addition, when the decompression is stopped, the timing at which the exhaust valve 25 opens the valve is set as shown in Fig. 5: the exhaust valve 25 is caused to open the valve by the foreign body cam 33. A phase that is slightly offset from the point in time. Next, the operation of the first embodiment will be described. The cam cam having a cam profile different from that of the exhaust cam 31 can be switched: the state in which the exhaust side rocker arm 39 is driven by the exhaust cam 31, and the camshaft 32. - Rotating - The foreign body cam 3 3 is driven by the state of the exhaust side rocker arm 39, and is mounted on the cam shaft 32' at a position where the exhaust cam 31 is held between the decompression cam 35 and the decompression cam 35. Therefore, the pressure reducing device 34A and the foreign body cam 33 can be used together to cause various changes in the valve driving characteristics of the exhaust valve 25, and the variable driving valve device 29A can be made compact. In addition, the cam shaft 32 rotatably supported by the cylinder head 13 through the first and second ball bearings 44 and 45 is provided between the first and second ball bearings 44 and 45. The air cam 30 and the exhaust cam 31, and the pressure reducing device 34A is disposed between the intake cam 30 and the exhaust gas 21 - 201013034 cam 31, so that the space between the intake cam 30 and the exhaust cam 31 can be effectively utilized. The pressure reducing device 34A is disposed, and the axial length of the cam shaft 32 can be prevented from being increased by the configuration of the pressure reducing device 34A. In addition, since the decompression device 34A is supported by the intake cam 30 and the exhaust cam 31, the decompression device 34A can be stably supported by the structure supported at both ends. Moreover, since the cam shaft 3 2 is provided with a center hole 5 7 , the center hole 57 extends coaxially with the cam shaft 32; and a guide hole 60 that is coupled to the center hole 57. A rod 59A extending between the inner peripheral surface and the outer peripheral surface of the cam shaft 32 and extending in the axial direction of the cam shaft 32, and "movable in the axial direction and coaxially inserted into the center hole 57" and " The foreign body cam 33 that is movable in the axial direction and attached to the outer circumference of the cam shaft 32 is connected by the coupling pin 61 that penetrates the guide hole 60; "the exhaust side rocker arm 39 can be driven by the exhaust cam The non-actuated position of the exclusive cam 33 of the 31 is isolated from the exhaust cam 31 and the position of the exhaust cam 31 that can move the exhaust side rocker 39 from the foreign body cam 33 to the exhaust cam 31 ◎ Since the lever driving means 63 for driving the lever 59A in the axial direction is coupled to the lever 59A, it is possible to switch the "exhaust" by a simple structure of "the lever 59A is driven in the axial direction by the lever driving means 63". The side rocker arm 39 is driven by the state of the exhaust cam 3 1", and "the exhaust side rocker arm 39 is In the state of the foreign body cam 33", since the special-body cam 33 normally rotates together with the cam shaft 32, generation of the knocking sound at the time of switching operation can be suppressed, and the rod 59A can be accommodated in the cam shaft 32, The enlargement of the camshaft 32 is avoided. -22- 25 201013034 Further, since the foreign body cam 33 is used to drive the exhaust valve, a part of the exhaust gas discharged from the combustion chamber 17 is returned to the exhaust gas recirculation cam of the combustion 17, and the foreign body is used. Since the cam 33 is disposed between the exhaust cam 31 and the second bearing 45, the cam shaft 32 is rotatable by the first and second ball shafts 44 and 45 on both sides of the intake cam 30 and the exhaust cam 31. The ground cylinder is supported by the cylinder head, whereby the cam shaft 32 can be pivotally supported and the foreign body cam 32 can be disposed. Fig. 9 is a cross-sectional view showing a second embodiment of the present invention, which corresponds to the third embodiment of the first embodiment. The parts corresponding to the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted. The intake valve 24 and the exhaust valve 25 are opened and closed by a variable drive door device 29B that is housed in a valve drive chamber 28 that forms a cylinder head 13 and a head cover 14, which is a variable drive steam. The door device 29B is provided with a cam shaft 32 disposed between the intake valve 24 and the exhaust valve φ, and is provided with an intake cam 30 and an exhaust cam 31; and a body cam 33, which is a body The cam profile of the cam 33 is different from the exhaust cam, and is movable in the direction of the shifting axis and is not rotatably mounted to the outer circumference of the aforementioned cam 32; and the pressure reducing device 34B is mounted with the aforementioned camshaft 32, and The exhaust cam 31 is held between the front and rear cams 3 3; and the intake and exhaust side swing shafts 36, 37, and the intake and exhaust side swing shafts 36, 37 are supported An axis parallel to the camshaft 32 is provided in the cylinder head 14; and an intake side rocker arm 3 8 is rotatably supported on the intake side swing shaft 36. The bearing number is in the steam and the gas is different from the 3 3 axis, and the bearing is further -23- 201013034. And driving the intake valve 24; and the exhaust rocker arm 39. The exhaust side rocker arm 39 is rotatably supported by the exhaust swing shaft 37, and is driven to have the exhaust cam 31 and the aforementioned body wheel 33. Or the pressure reducing cam 35 of the pressure reducing device 34B described above, and drives the exhaust valve 25 to open and close. The intake cam 30 and the exhaust cam 31 are integrally formed with the cam shaft 32 between the first and second ball bearings 44 and 45, and the intake cam 30 is placed on the first ball bearing 44 side, and the exhaust gas is exhausted. The cam 31 is disposed on the second bead bearing 45 side, and the dissimilar cam 33 is fitted between the intake cam 30 and the exhaust cam 31 on the outer circumference of the cam shaft 32, and the decompression device 34B is in the exhaust cam 31. The convex shaft 32 is attached to the second ball bearing 45. The foreign body cam 33 is fitted to the outer periphery of the cam shaft 32 so as to be "close to the exhaust cam 31 and abut against the abutment 39b of the exhaust side rocker arm 39" (indicated by a solid line in FIG. 9) 'movement' between the non-actuated position (indicated by a broken line in Fig. 9) that is separated from the exhaust cam 31 and is prevented from abutting against the abutting portion 39b" of the exhaust side rocker arm The cam shaft 32 is oriented in the axial direction and is not rotatable relative to the axis of the cam shaft 32. The rod 59B having a small diameter shaft 59Ba facing the bolt 58 coaxially at one end thereof is a central hole 57 which is movable in the axial direction and coaxially inserted into the front cam shaft 32, and is retracted between the rod 59B and the bolt 58. The movable spring 62' is coupled to the other end of the rod 59B with a rod driving means 63 for driving the rod 59B in the axial direction. The side camshaft is equipped with a roller wheel at the 39th position of the factory. The camshaft 32 is provided between the inner circumferential surface of the center hole 57 and the outer circumferential surface of the cam shaft 32, and is located at the camshaft. A guide hole 60 extending a long distance in the axial direction of the 32, and a different-body cam 33 attached to the outer circumference of the cam shaft 32 in the axial direction and the rod 59B are formed by a single joint pin 6 1 penetrating the guide hole 60 link. When the lever driving means 63 is actuated as "the turning lever 67 is rotated in the clockwise direction of the ninth drawing against the spring force of the return spring 62", the foreign body cam 33 is separated from the exhaust cam 31 to form a non- When the turning lever 67 is actuated to "rotate in the counterclockwise direction of FIG. 9 by the spring force of the return spring 62", the foreign body cam 33 moves closer to the exhaust cam 31 and abuts against the row. The operating position of the abutting portion 39b of the gas side rocker arm 39. The decompression device 34B includes a decompression weight 72 that is rotatably supported by the intake cam 30 and the exhaust cam 31 through a decompression pin 71B having an axis parallel to the cam shaft 32; And the decompression cam 35, φ, the decompression cam 35 is coupled to the weight reduction weight 72, and can protrude from the base circular portion 31a of the exhaust cam 31 in a state where the number of engine revolutions is low. The centrifugal force generated by the rotation of the cam shaft 32 abutting against the abutting portion 39a of the exhaust side rocker arm 39 does not abut against the abutment of the exhaust side rocker arm 39 when the decompression weight 72 is rotated. The connecting portion 39a and the decompressing device 34B are disposed between the exhaust cam 31 and the second ball bearing 45, and are supported by the intake cam 30 and the exhaust cam 31. The decompression weight 72 is formed in an arc shape and covers a slight half circumference of the cam shaft 32 from the side and is disposed between the step portion 32a and the exhaust cam 31 - 25 - 201013034 to partially slide the " The opposite side of the second ball bearing 45 is formed on the step portion 32a of the cam shaft 32", and at one end of the decompression weight 72 and the high position of the exhaust cam 31 located at the cam shaft 32 A cylindrical support protrusion 75 is interposed between the portions 31b. The decompression pin 71B is a member that penetrates the intake cam 30, the exhaust cam 31, the support protrusion 75, and the decompression weight 72 from the intake cam 30 side, and the decompression pin 71B moves in the axial direction. The stepped portion 32a of the cam shaft 32 and the outer peripheral portion of the washer 79 that "the inner peripheral portion is held between the inner ring 44a of the first ball bearing 44 and the cam shaft 32" are blocked by the outer peripheral portion of the washer 79. The coil-shaped torsion spring 80 of 75 is provided between the decompression weight 72 and the cam shaft 32, and the decompression weight 72 pushes the intermediate portion of the decompression weight 72 to the outer peripheral surface of the cam shaft 32. That side. The decompression cam 35 is rotatably supported by a decompression camshaft 84 having an axis parallel to the axis of the camshaft 32 and being implanted in the exhaust cam 31. The decompression cam 35 is a camshaft 32. Supported, it is rotatable about an axis parallel to the axis of the camshaft 32. In the decompression device 34B, the decompression cam 35 does not abut against the abutting portion 39a of the exhaust side rocker arm 39 in the decompression stop state in which the number of rotations of the cam shaft 32 is large, as in the first embodiment. The exhaust side rocker arm 39 is swung following the cam profile of the exhaust cam 31, and the exhaust valve 25 is also opened and closed at a time point following the cam profile of the exhaust cam 31. Further, in the decompression starting state in which the number of rotations of the cam shaft 3 2 is small, the abutting portion 39a of the arm 39 abuts against the arc portion 86' of the decompression cam 35 due to the exhaust side flap -26-201013034 The gas side rocker arm 39 is slightly rocked by the decompression cam 35 at the time point "the roller 54 is in contact with the base circle portion 31a of the exhaust cam 31", and the exhaust valve 25 is also formed: no relevant The cam profile of the exhaust cam 31 is opened, and the valve is opened at the time of closing the valve. According to the second embodiment, the foreign body cam 33' as the exhaust gas recirculation cam is disposed between the exhaust cam 31 and the intake cam 30, so that the exhaust cam 3 1 and the intake cam 3 can be effectively utilized. The foreign body cam 33 is disposed in a space of 0, and the increase in the axial length of the cam shaft 32 can be avoided by the arrangement of the foreign body cam 33. The above is a description of the embodiments of the present invention, but the present invention is not limited to the above embodiments, and various design changes are possible without departing from the scope of the invention described in the claims. Brief Description of the Drawings Fig. 1 is a longitudinal sectional view showing an important part of the engine in the first embodiment. Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1. Fig. 3 is an enlarged view of the portion indicated by arrow 3 in Fig. 2. Fig. 4 is a sectional view taken along line 4 - 4 of Fig. 3 in a state in which the decompression is stopped. Fig. 5 is a diagram showing the opening of the valve lift of the intake and exhaust valves. Fig. 6 is an enlarged view of line 6_6 of Fig. 3 in the state of decompression stop -27- 201013034. Fig. 7 is an exploded perspective view of the pressure reducing device. Fig. 8 is a cross-sectional view corresponding to Fig. 6 in a state in which the decompression is activated. Fig. 9 is a cross-sectional view corresponding to Fig. 3 showing the second embodiment. [Main component symbol description] @ 1 3 : Cylinder head 1 7 : Combustion chamber 24 : Intake valve 25 : Exhaust valve 29A, 29B as engine valve: Variable drive valve device 30 : Intake cam 3 1 : Exhaust cam 32 as a valve drive cam: Camshaft ❿ 33 : All-body cam 3 9 : Exhaust side rocker arm 44 as a valve drive member: First ball bearing 45 as a first bearing: As a second 2nd ball bearing of bearing 5 7 : Center hole 59 : Rod 60 : Guide hole 61 : Connecting pin -28- 201013034 63 : Rod driving method