1323308 九、發明說明： 【發明所屬之技術領域】 本發明係關於降低引擎起動時引擎的壓縮壓力之減壓 • 機構。 . 【先前技術】 先前’已知有降低引擎起動時引擎的壓縮壓力之減壓機 構（decompressor )(起動時減壓機構）。該種減壓機構有如 下述者：於凸輪軸之一端側設有大徑孔，於該大徑孔内配 置有引導組（guide lot)，於該引導組中將滑動式減壓凸 輪（cam)、與對該減壓凸輪施壓之彈簧（spring)排列於軸 方向’並且將使減壓凸輪移動之離心配重（governor weight)軸支撐於減壓凸輪之周圍外侧（例如專利文獻 又’減壓機構中亦有下述者：於凸輪軸上沿軸方向，排 列有減壓凸輪、外轂（h〇using)、施壓單元、以及離心配 重，該外轂能夠於凸輪軸之軸方向上移動並與減壓凸輪齒 鲁合’該施壓機構對該外轂施壓’該離心配重使外轂移動並 齒合於減壓凸輪（例如專利文獻2)。 [專利文獻1]曰本專利2746985號 [專利文獻2]曰本專利實公平2— 23770號公報 【發明内容】 (發明所欲解決之問題） 然而，上述專利文獻丨所記載者，因其沿凸輪軸之軸方 向依順配置滑動式減壓凸輪及彈簧等，故將導致減壓機構 之總長（凸輪軸軸方向之長度）變長，又，由於以銷（pin) 312ΧΡ/^®^*(ΜίΦ)/96-02/95140351 5 13-23308 將離心配重轴支撐於凸輪軸之大徑孔内，故而將使構造複 雜化且零件數增多，而導致減壓機構的大徑化。 又’上述專利文獻2所記載者’因沿著凸輪軸之軸方向 -排列減壓凸輪、外轂（相當於滑件）以及施壓單元等，故將 •導致減壓機構之總長變長，再者，為了使減壓凸輪與外轂 齒合，必須分別設置扣合爪，而使得該等零件形狀複雜化 並且需要採用齒合構造，由此導致減壓機構複雜化。 本發明係鑒於上述情形而形成者，目的在於提供可使機 構簡單化且小型化之減壓機構。 (解決問題之手段） 為解決上述課題，本發明之減壓機構，其特徵在於具 備.離心式調速器，其設於引擎之凸輪軸上，具有藉離心 配重之離心力而於該凸輪軸之軸方向上移動之滑件；減壓 凸輪，其一體設置於該離心式調速器之滑件上；以及施壓 構件，其設於上述凸輪軸外周部與上述滑件内周部之間， 籲於對抗上述離心力以阻止上述滑件移動之方向上對上述 滑件施壓。 根據本發明，由於具備：減壓凸輪，其一體設置於離心 式調速器之滑件上；以及施壓構件，其設於凸輪軸外周部 與滑件内周部之間，於對抗離心力以阻止滑件移動之方向 上對滑件施壓；故相較於將滑件與用於對滑件施壓之彈簧 沿凸輪軸之軸方向排列者、和將離心配重配置於減壓凸輪 之周圍外側者，可降低零件數，且縮短減壓機構之凸輪轴 軸方向之總長，並且使減壓機構小徑化。又’由於無須使 6 3 UXP/發明說明書(補件)/96_〇2/95140351 丄义3308 滑件與減壓凸輪齒合之齒合構造，故而可避免零件妒 雜化以簡化減壓機構。 / 於此情況下，較佳為設置移動阻止構件，其於上述凸輪 -軸上突出，用於阻止上述滑件向凸輪軸之圓周方向移動。 *根據該構成，可利用移動阻止構件使滑件與凸輪軸一體旋 轉。 於此情況下，較佳為使上述施壓構件夾持於上述滑件與 鲁上述凸輪軸之間。根據該構成，不需要對施壓構件進行定 位、保持之零件，故可降低零件數。 又，亦可於排氣門（exhaust valve)搖臂（r〇cker肛… •上設置抵接於上述減壓凸輪之臂部（arm)。根據該構成， 可將本減壓機構應用於動閥機構中具有搖臂之引擎中。 (發明效果） 本發明之減壓機構，由於具備：減壓凸輪，其一體設置 於離心式調速器之滑件上；以及施壓構件，其設於凸輪軸 _外周β卩與滑件内周部之間，於對抗離心力以阻止滑件之移 動的方向上對滑件施壓；故而可降低零件數且縮短減壓機 構之凸輪軸軸方向之總長，並且使減壓機構小徑化。又， 因不需要使滑件與減壓凸輪齒合之齒合構造，故可避免零 件形狀複雜化以簡化減壓機構。 ★又，本發明中，由於設有移動阻止構件，其於凸輪軸上 大出，以阻止滑件向凸輪軸之圓周方向移動，故而可使滑 件與凸輪轴一體旋轉。 又，本發明中，由於使施壓構件夾持於滑件與凸輪軸之 312ΧΡ/__ 書(補件)/%-02/95140351 7 ' 1323308 間，故而不需要對施壓構件進行定位 可降低零件數。 保持之零件 因此 又，本發明中，由於在排氣門搖臂上設置抵接 輪之臂部，故而可將本減壓機槿靡 、減垄凸 臂之引擎中。不成&機構應用於動閥機構中具有搖 【實施方式】 以下，參照圖式對本發明之實施形態加以說明。 圖1係具備本實施形態之減壓機構的小輪機踏車 (scooter)型車輛等二輪機車中所搭載之引擎的側剖面 圖。該引擎10係單汽知四行程循環引擎，具有曲轴箱 (/rank caseM! ' 汽缸體（cylinder bl〇ck)12、以及汽缸 1 (cylinder head)13。曲轴箱 u 中，曲軸（crank shaft)20旋轉自如地被支撐著，汽缸體12中形成有活塞 (pist〇n)22進行滑動之汽缸23，該活塞22透過連^ (connecting r〇d)21連接於曲軸2〇。又，曲軸2〇上配設 鲁有用以維持旋轉平衡之平衡配重（balance weight)2〇A。 汽缸蓋13固定於汽缸體12上且夹持汽缸蓋襯墊 (gasket)於其間，汽缸蓋13中形成有：燃燒室 (combustion chamber)30，其面對活塞22之頂面；進氣 口（intake port)32 ’其與該燃燒室30相連且開口於汽缸 盍13之背面；以及排氣口（exhaust port )31，其與燃燒 室30相連且開口於汽缸蓋13之前面。各孔口（port )31、 32中分別設有開閉該孔口之進氣門（intake valve)35及 排氣門（exhaust valve)36 ;開閉驅動該等進氣門35以及1323308 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a decompression mechanism for reducing the compression pressure of an engine when the engine is started. [Prior Art] A decompressor (decompression mechanism at the time of starting) which reduces the compression pressure of the engine at the time of starting the engine has been known. The pressure reducing mechanism has a large diameter hole provided at one end side of the cam shaft, and a guide lot is disposed in the large diameter hole, and a sliding pressure reducing cam (cam) is disposed in the guiding group And a spring that presses the decompression cam is arranged in the axial direction 'and a centrifugal weight shaft that moves the decompression cam is supported outside the decompression cam (for example, the patent document) Also included in the pressure reducing mechanism is a pressure reducing cam, an outer hub, a pressure applying unit, and a centrifugal weight arranged on the cam shaft in the axial direction, the outer hub being capable of the shaft of the cam shaft The direction moves and is engaged with the decompression cam tooth. The pressing mechanism presses the outer hub. The centrifugal weight moves the outer hub and is engaged with the decompression cam (for example, Patent Document 2). Japanese Patent No. 2,746, 985 [Patent Document 2] PCT Patent Publication No. 2-23770 (Draft of the Invention) (The problem to be solved by the invention) However, the above-mentioned patent documents are described as being along the axis of the cam shaft. According to the configuration, the sliding type decompression cam and the spring are arranged, so Will cause the total length of the decompression mechanism (the length of the camshaft axis direction) to be lengthened, and, in turn, the centrifugal counterweight shaft by pin 312ΧΡ/^®^*(ΜίΦ)/96-02/95140351 5 13-23308 Supported in the large diameter hole of the camshaft, the structure is complicated and the number of parts is increased, and the diameter of the pressure reducing mechanism is increased. Further, the above-mentioned Patent Document 2 describes the direction of the axis along the cam shaft. Arranging the decompression cam, the outer hub (equivalent to the slider), the pressure applying unit, etc., so that the total length of the decompression mechanism is lengthened, and in order to make the decompression cam and the outer hub to be engaged, the fastening must be separately provided. The claws make the shape of the parts complicated and require a toothed structure, thereby complicating the pressure reducing mechanism. The present invention has been made in view of the above circumstances, and an object thereof is to provide a pressure reduction mechanism that can simplify the mechanism and miniaturize the mechanism. (Means for Solving the Problem) In order to solve the above problems, the pressure reducing mechanism of the present invention is characterized in that it is provided with a centrifugal governor which is provided on a cam shaft of an engine and has a centrifugal force by a centrifugal weight. In the direction of the axis of the camshaft a moving sliding member; a pressure reducing cam integrally provided on the sliding member of the centrifugal governor; and a pressing member disposed between the outer peripheral portion of the cam shaft and the inner peripheral portion of the sliding member The centrifugal force applies pressure to the sliding member in a direction preventing the sliding member from moving. According to the present invention, the pressure reducing cam is integrally provided on the sliding member of the centrifugal governor; and the pressing member is provided Between the outer peripheral portion of the cam shaft and the inner peripheral portion of the slider, the sliding member is pressed against the centrifugal force to prevent the sliding member from moving; therefore, the cam is pressed along the cam and the spring for pressing the sliding member When the axial direction of the shaft is arranged and the centrifugal weight is disposed outside the pressure reducing cam, the number of parts can be reduced, the total length of the camshaft axis direction of the pressure reducing mechanism can be shortened, and the pressure reducing mechanism can be reduced in diameter. In addition, since there is no need to make the 6 3 UXP/invention manual (supplement)/96_〇2/95140351 丄义3308 slider and the decompression cam toothed to the toothed structure, the part can be prevented from being complicated to simplify the pressure reducing mechanism. . In this case, it is preferable to provide a movement preventing member which protrudes on the cam-shaft to prevent the slider from moving in the circumferential direction of the cam shaft. * According to this configuration, the slider can be integrally rotated with the cam shaft by the movement preventing member. In this case, it is preferable that the pressing member is interposed between the slider and the cam shaft. According to this configuration, it is not necessary to position and hold the pressing member, so that the number of parts can be reduced. Further, an exhaust valve arm can be attached to the exhaust valve (r〇cker anus). The arm can be applied to the arm of the decompression cam. According to this configuration, the present decompression mechanism can be applied to the moving arm. The valve mechanism has an engine of a rocker arm. (Effect of the invention) The pressure reducing mechanism of the present invention includes: a pressure reducing cam which is integrally provided on a slider of the centrifugal governor; and a pressing member which is provided at Between the camshaft_outer circumference β卩 and the inner peripheral portion of the slider, the sliding member is pressed in a direction against the centrifugal force to prevent the movement of the slider; therefore, the number of parts can be reduced and the total length of the camshaft axis direction of the pressure reducing mechanism can be shortened. Further, since the pressure reducing mechanism is reduced in diameter, since the toothed structure in which the slider and the decompression cam are engaged is not required, the shape of the part can be prevented from being complicated to simplify the pressure reducing mechanism. Further, in the present invention, A movement preventing member is provided which is large on the cam shaft to prevent the sliding member from moving in the circumferential direction of the cam shaft, so that the sliding member and the cam shaft can be rotated integrally. Further, in the present invention, the pressing member is clamped 312ΧΡ/__ for the slider and camshaft (Repair) /%-02/95140351 7 'Between 1323308, it is not necessary to position the pressing member to reduce the number of parts. The part to be held is therefore, in the present invention, the abutment is provided on the exhaust valve rocker arm. The arm of the wheel can be used in the engine of the decompressing machine and the ridge reducing arm. The mechanism is not applied to the moving valve mechanism. [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a side cross-sectional view of an engine mounted in a two-wheeled vehicle such as a small-engined scooter type vehicle including the pressure reducing mechanism according to the embodiment. The engine 10 is a single-stroke four-stroke cycle engine having a crankshaft. a tank (/rank caseM! 'cylinder bl〇ck) 12 and a cylinder head 13. In the crankcase u, a crank shaft 20 is rotatably supported, and a cylinder block 12 is formed therein. The piston (pist〇n) 22 performs a sliding cylinder 23, which is connected to the crankshaft 2 through a connecting rod 21. Further, the crankshaft 2 is provided with a balance weight which is useful for maintaining the balance of rotation. (balance weight) 2〇A. Cylinder head 13 solid Positioned on the cylinder block 12 and sandwiching a cylinder head gasket therebetween, a cylinder chamber 13 is formed with a combustion chamber 30 facing the top surface of the piston 22; an intake port 32' is connected to the combustion chamber 30 and opens to the back of the cylinder bore 13; and an exhaust port 31 connected to the combustion chamber 30 and opening in front of the cylinder head 13. Ports 31 And 32 are respectively provided with an intake valve 35 and an exhaust valve 36 for opening and closing the orifice; and opening and closing the intake valves 35 and
312XP/發明說明書(補件)/96-02/95140351 S 3 5以及排氣門3 6保持關閉狀態，則僅因活塞2 2壓縮汽 缸23内以及燃燒室30内之空氣（或者混合氣體），就會導 致曲軸20旋轉不靈活。因此，當將自起動（self starting) 方式應用於引擎起動方式中時，尤其是大排氣量之引擎或 壓縮比較高之引擎時必須使自起動馬達（self starting m〇t〇r)大型化，又，當使用腳踏起動（kick starting)方 式時，則須要較強的腳踏力。 因此，於本實施形態中，將引擎起動時之壓縮行程α 中打開排氣門36的減壓機構7G g己置於凸輪軸5Q上，利 用該減壓機構70降低引擎起動時之壓縮壓力。 如圖2所示，減壓機構7〇具備離心式調速器8〇，該離 心式調速器8G係藉由凸輪# 5G之旋轉力而使減壓機構 作動’該離心式調速器8〇配置於凸輪軸5〇之排氣凸 輪46與支持凸輪軸5〇的其中一軸承之間。該離心式 調速器80包括：滑件8卜其由凸輪軸5()所插通並於凸 輪軸5G之軸方向上移動自力；以及配重保持體⑽，其由 凸輪轴5G所插通並在與滑件81之間保 錢 (球狀）82。 如，3(a)、⑻、（c)所示，滑件81 一體地包括：筒部 > ，八由凸輪軸50所插通；護套部（guard) 86，其延 外周部；以及減壓凸輪87，其相對於 :=空上出間隔配置於筒部85之轴方向(=凸輪轴 如圖3(b)所示’筒部85具有大致圓筒形狀於内周部 3】2XP/發明說明書(補件)/96-02/95140351 „ ζ ⑶3308 =減壓凸輪87的相反側，形成有 大出部m，該内周突出部8δΑ =之内周 ，(圖2)可轉動配合(run:二 之外D1係凸輪軸50之由軸承48所支持的支持部 筒部85去掉内周突出部88A的部分 =對於外徑職>D1，參照圖2)可轉 ： :分之外徑;… ^ 88LTr# C1 180 89A , •。"9“靖部85之減壓凸輪⑺側之端面向外部開口。 ㈣件81係’如圖2所示’以下述方式插人有凸 5〇’即，插通凸輪軸50之卡止銷（移動阻止構件）9〇之自 =轴50突出之兩端分別***上述槽部89A中；藉此， 》月件移動自如地配置於凸輪軸5〇之轴方向，並且 φ 阻止滑件81向凸輪轴50圓周方向移動，使得 /月件81與凸輪軸5〇 —體旋轉。 >護套部86係具有延伸設置於筒部的之整個外側周上之 護套形狀，且如圖3(b)所示，與減壓凸輪们相反侧之面 86A形成為傾斜面，該傾斜面係隨著向護套部86外周方 向移動，距離筒部85之減壓凸輪87的距離M逐漸變大。 如圖3(c)所示，該傾斜面86Α上一體形成有多個導轨 85Β，其等用以於筒部85之中心軸C1之放射方向上分別 對多個球狀離心配重82(圖2)加以引導。本實施形態中， 312XP/發明說明書(補件)/96-02/95140351 12312XP/Invention Manual (Supplement)/96-02/95140351 S 3 5 and the exhaust valve 36 remain in the closed state, and only the piston 2 2 compresses the air (or mixed gas) in the cylinder 23 and in the combustion chamber 30, This will cause the crankshaft 20 to rotate inflexibly. Therefore, when the self starting method is applied to the engine starting mode, especially for a large exhaust engine or a relatively high compression engine, the self starting motor (self starting m〇t〇r) must be enlarged. Moreover, when using the kick starting method, a strong pedaling force is required. Therefore, in the present embodiment, the pressure reducing mechanism 7Gg that opens the exhaust valve 36 in the compression stroke α at the time of starting the engine is placed on the cam shaft 5Q, and the pressure reducing mechanism 70 is used to reduce the compression pressure at the time of starting the engine. As shown in FIG. 2, the pressure reducing mechanism 7A is provided with a centrifugal governor 8G which operates the pressure reducing mechanism by the rotational force of the cam #5G'. The centrifugal governor 8 The 〇 is disposed between the exhaust cam 46 of the camshaft 5〇 and one of the bearings supporting the camshaft 5〇. The centrifugal governor 80 includes a slider 8 that is inserted by the cam shaft 5 () and moves in the axial direction of the cam shaft 5G; and a weight holding body (10) that is inserted by the cam shaft 5G. And a money (spherical) 82 is secured between the slider 81 and the slider 81. For example, as shown in 3(a), (8), and (c), the slider 81 integrally includes: a tubular portion>, which is inserted by the cam shaft 50, and a guard 86 which extends the outer peripheral portion; The decompression cam 87 is disposed in the axial direction of the tubular portion 85 with respect to the:=empty uppering interval (=the camshaft is as shown in FIG. 3(b). The tubular portion 85 has a substantially cylindrical shape on the inner peripheral portion 3] 2XP /Invention Manual (Supplement)/96-02/95140351 „ ζ (3) 3308 = opposite side of the decompression cam 87, a large portion m is formed, and the inner circumference protrusion 8δΑ = inner circumference, (Fig. 2) is rotatably fitted (run: the portion of the D1 camshaft 50 that is supported by the bearing 48 and the portion of the support portion cylindrical portion 85 that is removed by the inner peripheral projection portion 88A = for the outer diameter position > D1, with reference to Fig. 2): Outer diameter;... ^ 88LTr# C1 180 89A , •."9" The end of the relief cam (7) side of the Jing 85 is facing the outside opening. (4) The 81 series 'shown in Figure 2' is inserted in the following way. 5〇', the two ends of the locking pin (moving preventing member) 9 that is inserted into the cam shaft 50 are inserted into the groove portion 89A, respectively, and the moon piece is movably disposed on the cam. Axle 5 axis And, φ prevents the slider 81 from moving in the circumferential direction of the cam shaft 50, so that the moon member 81 and the cam shaft 5 are rotated in the body. The sheath portion 86 has an entire outer circumference extending over the tubular portion. As shown in Fig. 3(b), the surface 86A opposite to the decompression cams is formed as an inclined surface which is moved toward the outer circumferential direction of the sheath portion 86 and is reduced by the distance from the cylindrical portion 85. The distance M of the pressing cam 87 is gradually increased. As shown in Fig. 3(c), the inclined surface 86 is integrally formed with a plurality of guide rails 85, which are respectively used for the radial direction of the central axis C1 of the cylindrical portion 85. The plurality of spherical centrifugal weights 82 (Fig. 2) are guided. In the present embodiment, 312XP/invention specification (supplement)/96-02/95140351 12
構成為藉由該I 丨2個離心配重82軌咖能夠以等間隔⑽度間⑽導 減麗凸輪8 7彳备m 氣…凸輪:： = 1°於屋縮行…打開排 之凸輪輪汽^ v圖3(a)所不，形成為具有上推部87A == 廊，該上推部m係㈣縮行 所具備之臂部56A(圖2)。再者，如圖3二 凸輪87之凸輪輪廊除上推部87A以外，係形 狀:同圖(a)中以二點虛線表示該正圓之軌跡。 方延二“不上述臂部56A具有自排氣門搖臂56向側 =2!下方延伸之形狀，配置於不會干擾排氣凸輪 部8 W。該臂部5 6 A係，藉由與減壓凸輪8 7之上推 ::接’而將與臂部56A為一體之排氣門搖臂冗的 再者，該臂部56A既可與排氣門搖臂5 ⑩又，亦可❹其他零件製造並連接於錢門搖臂56上。 如圖4(a)、（b)、（c)所示，配重保持體83係、於中央具 有貫通孔83A之環狀板構件，該貫通孔83A之内徑 成為與凸輪軸50之外徑D1大致同徑的值。如圖2所示， 該配重保持體83係’於上述滑件81由凸輪轴5〇所插通 之後該配重保持體83由凸輪軸5〇插通’貫通孔ΜΑ之周 圍與支持凸輪軸50之其中一軸承48的内圈相接觸，該内 圈接觸部謂之外側形成為向滑件81側傾斜之傾斜部 83C，且形成為該配重保持體83僅與軸承48之内圈接觸 312XP/發明說明書(補件)/96-02/95140351 丄 之形狀。 於该傾斜部83C與滑件81之護套部86之間，沿凸輪軸 50之外周方向等間隔（3〇度間隔）配置有離心配重82。如 圖2所示，該傾斜部83c與滑件81之護套部86，由於形 成為沿凸輪軸50之外周方向移動而互相接近之形狀，故 而構成為即使離心配重82藉由凸輪軸5〇旋轉所產生之離 心力而向離心方向移動，離心配重82亦會受到傾斜部83C 鲁與滑件81之護套部86夾持，而不會向外脫落。再者，圖 2表示凸輪軸50旋轉而使離心力作用於離心配重82之狀 態，即，表示引擎處於運轉中之狀態。 此處’如圖2所示，於上述滑件81内周部與凸輪軸5〇 外周部之間配置有向排氣凸輪46之相反方向對該滑件81 施壓的施壓構件95。該施壓構件95係，使用有圈狀彈簧， 一端抵接於凸輪軸50之外徑D2部分與外徑D1部分〇)2 >D1)之段差部92，另一端抵接於滑件81之内周突出部 籲88A之段差部，藉此夾持於滑件81與凸輪軸5〇之間，沿 著凸輪軸50之軸方向向排氣凸輪46之相反方向對滑件 81施壓。 其次，參照圖2 ,對該減壓機構7〇之組裝順序加以說 明。再者，前提係於組裝軸承48之前將該減壓機構7〇組 裝於凸輪軸50上。首先，將卡止銷9〇插通凸輪軸5〇並 且插通施壓構件95，於此狀態下，自凸輪軸5〇之一端側 ***滑件81，使卡止銷90之兩端***該滑件81之槽部 89A内。其次，自凸輪軸50之一端側插通配重保持體83， 312XP/發明說明書(補件)/96·°2/9514〇351 14 將離心配重82配置於該配重保持體83與滑件81之護套 部86之間’並且依順將軸承48、分隔件49、從動鏈輪 61 、 以及凸緣62安裴於凸輪轴50。如此，僅將構成減壓機 構70之各零件依順***凸輪軸50，就可容易地組裝減壓 機構70。 其次，對減壓機構7〇之動作加以說明。圖5(a)、（b) 係表示引擎起動時之減壓機構7〇的圖。再者，圖5(a)表 ⑩:引擎10於壓縮行程α之情況，圖5(b)表示引擎1〇於 慶縮行程α以外之情況。 引擎起動時，凸輪軸5〇呈極低速旋轉或旋轉數大致為 零，此時，由於離心配重82中幾乎不產生離心力，故而 滑件81因施壓構件95之施壓力向排氣凸輪心相反方 向移動’藉由該移動’離心配重82沿滑件81之護套部 祁之傾斜面86Α以及配重保持體83之傾斜部83c向最^ 周=動’滑件81停止於抵接移動至該最内周侧的離心 籲配重82之位置（以下稱為第j位置）。 如圖5(a)、⑻所示，該第1位置係相當於滑件μ 所设置之減壓凸輪87對向於排氣門搖臂 位置。因此，當引擎！。於壓縮行程α之情：：5:的 5⑷所示，減壓凸輪87之上推部m將與 圖 體之排氣門搖㈣上推，使排氣門搖臂56自排= 46僅子起間隙5，由此打開排氣門36。 輪 另一方面，當引擎10於壓縮行程α以外之 圖5⑻所示’減壓凸輪87之上推部m並不二:二 312ΧΡ/發明說明書(補件)/96>〇2/95140351 j5 丄 56A排氣門搖臂56保持為抵接於排氣凸輪w之狀態， 依Z氣凸輪46之凸輪輪靡而使排氣門36開閉。 人對自上述狀態凸輪軸之旋轉數增加後（引擎起 動後?的減壓機構之動作加以說明。此處，_ 6(a)、 (b)係表示引擎起動後之減壓機構70的圖，冑6(a)表示 引擎1〇於壓縮行程α之情況，圖6(b)表示引擎1〇於壓 縮行程α以外之情况。 备紋轉數自凸輪軸50呈極低速旋轉或旋轉數為零之狀 態開始增加時，作用於離心配重82之離心力變大，則離 心配重+82之離心力作用於滑件81之護套部86之傾斜面 86Α藉此產生使滑件8丨向排氣凸輪側移動之力，當 該力超過施歷構j牛95之施壓力時，滑# 8 ^對抗施壓構件 95之施壓力而向排氣凸輪46側移動，藉此，如圖6(a)、 (b)所不，滑件81移動至抵接排氣凸輪“之位置（以 為第2位置）。 •該第2位置係相當於滑件81上所設置之減壓凸輪87避 處於排乳門搖臂56之臂部56A與排氣凸輪46之間之間隙 的位置，即，相當於不與臂部56A抵接之非抵接位置。因 此，於引擎起動後，即使引擎1〇處於壓縮行程α '燃燒 步驟、排氣行程以及進氣行程中任一環節，如圖6(心、 (b^所不，排氣門搖臂56仍然抵接於排氣凸輪铛，依照 排氣凸輪46之凸輪輪廓而使排氣門36開閉。 因此，利用上述減壓機構70，僅於引擎起動時於引擎 1〇之壓縮行程α中打開排氣門36,藉此降低引擎起動時 312ΧΡ/發明說明書(補件)/96-02/95140351 16 1323308 之壓縮壓力。因此’當引擎起動方式為使用自起動方式 時，相較於不具備減壓機構者可採用小型自起動馬達， 又，當使用腳踏起動方式時，能夠降低引擎起動時所須之 腳踏力，可易於使引擎起動。 ' 本實施形態中，上述減壓機構7〇具備離心式調速器 80，該離心式調速器80包括：滑件81，其由凸輪軸5〇 所插通；以及配重保持體83，其由凸輪軸5〇所插通並與 滑件81之間保持離心配重82 ;且在該滑件81内周部與 響凸輪轴50外周部之間配置有對該滑件81施壓之施壓構件 95 ’故而相較於沿凸輪軸之軸方向依順配置滑件及用於向 滑件施壓之彈簧的習知者，可縮短減壓機構7〇之凸輪轴 軸方向之總長。 又，本構成中，由於施壓構件95夾持於滑件81與凸輪 軸50之間，故而不需要對施壓構件95進行定位及保持之 零件，進而，由於使減壓凸輪87一體形成於滑件81上， φ故而相較於將滑件與減壓凸輪製成不同零件之習知者，可 降低零件數，因此亦可縮短減壓機構7〇之凸輪軸軸方向 之總長。又，由於不需要如習知般設置使滑件與減壓凸輪It is configured that the I 丨 2 centrifugal weights 82 rails can be used at equal intervals (10) degrees (10) to guide the reduction cam 8 7 m m gas ... cam:: = 1 ° in the house contraction line ... open the cam wheel The steam is not shown in Fig. 3(a), and is formed with an uplifting portion 87A == a gallery, and the pushup portion m is a fourth portion of the arm portion 56A (Fig. 2). Further, as shown in Fig. 3, the cam wheel gallery of the cam 87 has a shape other than the push-up portion 87A: the trajectory of the perfect circle is indicated by a two-dot chain line in the same figure (a). Fang Yan 2 "The above-mentioned arm portion 56A has a shape extending from the exhaust valve rocker arm 56 to the side = 2!, and is disposed so as not to interfere with the exhaust cam portion 8 W. The arm portion 5 6 A is The decompression cam 8 7 pushes up: "connects" and the exhaust valve rocker integrated with the arm portion 56A is redundant. The arm portion 56A can be combined with the exhaust valve rocker arm 5 10 or The other parts are manufactured and connected to the money gate rocker 56. As shown in Fig. 4 (a), (b), and (c), the weight holding body 83 is an annular plate member having a through hole 83A at the center. The inner diameter of the through hole 83A is a value substantially equal to the outer diameter D1 of the cam shaft 50. As shown in Fig. 2, the weight holding body 83 is after the slider 81 is inserted by the cam shaft 5'. The weight holding body 83 is in contact with the inner ring of one of the bearings 48 supporting the cam shaft 50 by the periphery of the through hole ΜΑ, and the outer ring contact portion is formed to be inclined toward the slider 81 side. The inclined portion 83C is formed such that the weight holding body 83 is only in contact with the inner ring of the bearing 48 312XP / invention specification (supplement) / 96-02 / 95140351 。. The inclined portion 83C and the slider 81 The centrifugal weight 82 is disposed between the sheath portions 86 at equal intervals (3 degrees intervals) in the outer circumferential direction of the cam shaft 50. As shown in Fig. 2, the inclined portion 83c and the sheath portion 86 of the slider 81 are Since they are formed in a shape that moves closer to each other in the circumferential direction of the cam shaft 50, the centrifugal weight 82 is tilted even if the centrifugal weight 82 is moved in the centrifugal direction by the centrifugal force generated by the rotation of the cam shaft 5〇. The portion 83C is clamped to the sheath portion 86 of the slider 81 without coming off. Further, Fig. 2 shows a state in which the cam shaft 50 rotates to cause centrifugal force to act on the centrifugal weight 82, that is, the engine is in operation. Here, as shown in FIG. 2, a pressure applied to the slider 81 in the opposite direction to the exhaust cam 46 is disposed between the inner peripheral portion of the slider 81 and the outer peripheral portion of the cam shaft 5〇. The member 95 is a ring-shaped spring, and one end abuts against the step portion 92 of the outer diameter D2 portion of the cam shaft 50 and the outer diameter D1 portion 〇) 2 > D1), and the other end abuts The inner peripheral protrusion of the slider 81 is called the step portion of the 88A, thereby being clamped to the slider 81 and the cam shaft 5 The slider 81 is pressed in the direction opposite to the exhaust cam 46 along the axial direction of the cam shaft 50. Next, the assembly procedure of the pressure reducing mechanism 7A will be described with reference to Fig. 2. The pressure reducing mechanism 7 is assembled to the cam shaft 50 before assembling the bearing 48. First, the locking pin 9 is inserted through the cam shaft 5〇 and inserted into the pressing member 95, in this state, from the cam shaft 5〇 One end side is inserted into the slider 81 so that both ends of the locking pin 90 are inserted into the groove portion 89A of the slider 81. Secondly, the weight holding body 83 is inserted from one end side of the cam shaft 50, 312XP/invention specification (Parts) / 96 · ° 2 / 9514 〇 351 14 The centrifugal weight 82 is disposed between the weight holding body 83 and the sheath portion 86 of the slider 81 ' and the bearing 48, the partition 49, the follower The sprocket 61 and the flange 62 are mounted to the camshaft 50. Thus, the pressure reducing mechanism 70 can be easily assembled by simply inserting the components constituting the pressure reducing mechanism 70 into the cam shaft 50. Next, the operation of the pressure reducing mechanism 7 will be described. Fig. 5 (a) and (b) are views showing the pressure reducing mechanism 7A at the time of starting the engine. Further, Fig. 5(a) shows the case where the engine 10 is in the compression stroke α, and Fig. 5(b) shows the case where the engine 1 is outside the contraction stroke α. When the engine is started, the camshaft 5 is rotated at a very low speed or the number of revolutions is substantially zero. At this time, since the centrifugal force is hardly generated in the centrifugal weight 82, the slider 81 is pressed toward the exhaust cam by the pressing force of the pressing member 95. Moving in the opposite direction 'by this movement' the centrifugal weight 82 is stopped along the inclined surface 86 of the sheath portion of the slider 81 and the inclined portion 83c of the weight holding body 83 to the most circumferentially-moving slider 81 The position of the centrifugal call weight 82 (hereinafter referred to as the jth position) is moved to the innermost circumference side. As shown in Figs. 5(a) and (8), the first position corresponds to the position of the exhaust cam arm of the exhaust cam 87 provided by the slider μ. So when the engine! . As shown in 5(4) of the compression stroke α::5:, the push-up portion m of the decompression cam 87 pushes up the exhaust valve of the figure (four), so that the exhaust valve rocker 56 is self-discharged = 46 only The gap 5 is opened, thereby opening the exhaust valve 36. On the other hand, when the engine 10 is outside the compression stroke α, the push-down portion m is not shown on the decompression cam 87 shown in Fig. 5 (8): two 312 ΧΡ / invention specification (supplement) / 96 > 〇 2 / 95140351 j5 丄The 56A exhaust valve rocker arm 56 is held in contact with the exhaust cam w, and the exhaust valve 36 is opened and closed in accordance with the cam rim of the Z gas cam 46. The operation of the decompression mechanism after the engine is started is increased after the number of rotations of the cam shaft in the above state is increased. Here, _ 6 (a) and (b) are diagrams showing the decompression mechanism 70 after the engine is started.胄6(a) shows the case where the engine 1 is in the compression stroke α, and Fig. 6(b) shows the case where the engine 1 is outside the compression stroke α. The number of rotations of the preparation is rotated from the camshaft 50 at a very low speed or the number of rotations is When the state of zero starts to increase, the centrifugal force acting on the centrifugal weight 82 becomes larger, and the centrifugal force of the centrifugal weight +82 acts on the inclined surface 86 of the sheath portion 86 of the slider 81, thereby causing the slider 8 to be aligned. When the force exceeds the applied pressure of the actuator, the slip #8^ moves against the pressing force of the pressing member 95 to the side of the exhaust cam 46, thereby, as shown in Fig. 6 ( a), (b) No, the slider 81 moves to a position that abuts the exhaust cam "is considered to be the second position." • The second position corresponds to the decompression cam 87 provided on the slider 81. The position of the gap between the arm portion 56A of the breast pump rocker arm 56 and the exhaust cam 46, that is, the non-contact position that does not abut against the arm portion 56A Therefore, after the engine is started, even if the engine 1〇 is in any of the compression stroke α 'burning step, exhaust stroke and intake stroke, as shown in Fig. 6 (heart, (b^ no, exhaust valve rocker 56) Still abutting against the exhaust cam 铛, the exhaust valve 36 is opened and closed according to the cam profile of the exhaust cam 46. Therefore, by the above-described pressure reducing mechanism 70, the row is opened only in the compression stroke α of the engine 1 when the engine is started. The valve 36, thereby reducing the compression pressure of the engine starting 312 ΧΡ / invention manual (supplement) / 96-02 / 95140351 16 1323308. Therefore, when the engine starting mode is the self-starting mode, compared with no decompression The mechanism can be a small self-starting motor, and when the kick start mode is used, the pedaling force required for starting the engine can be reduced, and the engine can be easily started. In the embodiment, the pressure reducing mechanism 7 is provided. a centrifugal governor 80, the centrifugal governor 80 includes: a slider 81 that is inserted by the camshaft 5〇; and a weight retaining body 83 that is inserted by the camshaft 5〇 and the slider Maintaining a centrifugal weight 82 between 81; and in the slider 81 A pressing member 95 that presses the slider 81 is disposed between the peripheral portion and the outer peripheral portion of the ring cam shaft 50. Therefore, the slider is disposed in accordance with the axial direction of the cam shaft and the sliding member is pressed. The conventional spring can shorten the total length of the camshaft axis direction of the pressure reducing mechanism 7 。. In this configuration, since the pressing member 95 is sandwiched between the slider 81 and the cam shaft 50, it is not necessary to apply The pressing member 95 performs the positioning and holding of the parts, and further, since the decompression cam 87 is integrally formed on the slider 81, φ can be reduced as compared with the conventional member in which the slider and the decompression cam are made of different parts. Therefore, the total length of the camshaft axis direction of the pressure reducing mechanism 7〇 can also be shortened. Moreover, since it is not necessary to provide the slider and the decompression cam as conventionally
齒合之齒合構造，故而可避免零件形狀複雜化，因此可簡 化減壓機構。 S 進而，本構成中，由於離心配重82保持於由凸輪軸5〇 所插通之滑件81與配重保持體83之間，故而於凸輪軸之 一端侧設置大徑孔，並於該大徑孔内配置引導組，該q導 組中將減壓凸輪與彈簧配置於軸方向，由此相較於在其周 312XP/發明說明書(補件)/96_〇2/9514()351 17 1323308 圍外側轴支撐使減壓凸輪移動之離心配重者，將不需要軸 支撐離心配重之構件，故能夠進一步降低零件數以及簡化 機構，且無須將離心配重配置於減壓凸輪之周圍外側，故 - 可使減壓機構小徑化。 - 藉此’本構成之減壓機構7 0可實現整體形狀之小型化 以及輕量化。因此，藉由採用該減壓機構7〇，亦能夠實 現降低引擎10之旋轉負荷、汽缸蓋13之小型化、以及汽 缸蓋13周圍之輕量化。 • (2)第2實施形態 圖7以及圖8(a)、（b)表示第2實施形態。 該實施形態中，表示以下述方式構成了離心式調速器 100之減壓機構200 :該離心式調速器丨〇〇係於滑件ι〇1 之内侧配置有向排氣凸輪4 6側對滑件1 〇 1施壓之施壓構 件115，當引擎1 〇起動時滑件i〇丨沿凸輪轴5〇向排氣凸 輪46之相反側移動。再者，為便於說明，對與第1實施 _形態大致相同之零件標記相同符號，並省略詳細說明。 如圖7所示，離心式調速器1〇〇包括滑件ι〇1，其由凸 輪軸50所插通並於凸輪軸5〇之軸方向上移動自如；以及 配重保持體103，其由凸輪轴所插通並與滑件1〇1之 間保持多個離心配重（球狀）8 2。 滑件101 —體包括：大致圓筒形狀之筒部1〇5，設於該 筒部105之一端侧之護套部1〇6，以及設於與筒部1〇5之 濩套部相反侧之減壓凸輪丨〇7。筒部丨〇5係減壓凸輪1 〇7 侧之内周徑形成為相對於凸輪軸5〇之外徑Μ可轉動配合 312XP/發明說明書(補件)/96_02/9514〇35】 1323308 之大致同徑的值，並且形成延伸設置於筒部⑽ 的槽部119Λ，插通凸輪軸50且一 釉方向 阻止構件）11G的突出端插人於該槽部U9A中。_銷(移= 件101移動自如地配置於凸輪轴5〇之轴方向，^ ^ 卡止銷11〇阻止滑件101向凸輪轴5〇之圓周方=由 又，筒部1〇5之護套部106側之内周徑 内周徑之大徑，藉此，如圖7所示，當將筒部1〇5:通： 凸輪軸50之情況下，與凸輪軸5〇 、於 # Π ^ ^ ^ ,, e 之間开夕成有配置施壓構 115之配置_ 116。該施壓構件115係例如 彈簧，配置間隙116中所配置之施壓構件115 一 =狀 接於配置間隙U6内部之壁部m，另一端抵接於;;= 二8:環構件118介插滑件m與支持凸輪軸心軸承 減壓凸輪107具有固定於锊1nc , 1η7Δ Ώ U疋於4部外周部之環構件 :以及固定於該環構件職外周部之凸輪部跡 再者’環構件mA以及凸輪部107B可形成為一體，又， 亦可將該等與滑件101形成為一體。 配重保持體103具有可使滑件1〇1自由***之大致圓筒 更具體而言，内徑具有相對於固定於滑件ι〇ι之環 構件107A可轉動配合之徑’並且具有所***之滑件ι〇ι 之凸輪部刪能夠通過的開口職，進而，一體包括於 由凸輪軸50插通之狀態下向轴承48側 部 103C〇 該減壓機構200之組裝係，首先，將配重保持體1〇3插 312XP/發明說明書(補件)/96-02/95140351 19 (· 1 1323308 入至凸輪軸50之後，將滑件ιοί***至凸輪軸5〇並*** 配重保持體103内，其次，將施壓構件115***至該滑件 101之配置間隙116中之後，將環構件118***至凸輪軸 50，藉此將減壓機構200組裝於凸輪軸5〇。 其次，就減壓機構200之動作加以說明。圖8(a)表示 引擎起動時之減壓機構200，圖8(b)表示引擎起動後之減 壓機構200。 引擎起動時，凸輪軸50呈極低速旋轉或旋轉數大致為 零，此時，由於離心配重82上幾乎不產生離心力，故而 滑件101藉由施壓構件115之施壓力向排氣凸輪46側移 動，藉由該移動，離心配重82沿滑件1〇1之護套部ι〇6 以及配重保持體103之傾斜部103C向最内周側移動，滑 ’件101停止於抵接移動至該最内周側之離心配重82之位 置（以下稱為第1位置）。 如圖8(a)所示，該第i位置係相當於滑件1〇1上所設 鲁置之減壓凸輪107對向於排氣門搖臂56之臂部56a的位 置。因此，當引擎10於壓縮行程α之情況下，如圖8(a) 所:，減壓凸輪107之上推部87A將與臂部56A為一體之 排乳門搖臂56上推，由此使排氣門搖臂56自排氣凸輪 46僅浮起間隙占而打開排氣門36。另一方面，當引擎 1 〇於壓縮行程α以外之情況下，減壓凸輪1 〇7之上推部 87Α並不抵接於臂部56Α，排氣門搖臂56抵接於排氣凸輪 並依了、排氣凸輪46之凸輪輪廊而使排氣門36開閉。 又，當旋轉數自凸輪軸5〇呈極低速旋轉或旋轉數為零 爾發明說明書(補件)/96〇2/951侧 13.23308 之狀態開始增加時，作用於離心配重82之離心力變大， 離心配重82之離心力作用於配重保持體1()3之傾斜部 i〇3C^藉此產生使滑件101向排氣凸輪46相反側移動之 力，當該力超過施壓構件115之施壓力時，滑件ι〇ι對抗 施壓構件115之施壓力向排氣凸輪46相反側移動，藉此， 如圖8(b)所示，滑件101移動至抵接環構件118之位^ 下稱為第2位置）。 該第2位置係相當於滑件1〇1上所設置之減壓凸輪 不與排氣門搖臂56之臂部56A抵接之非抵接位置。因此， 於^擎起動後，即使引擎10處於壓縮行程α、燃燒步驟、 排氣行程以及進氣行程中任一環節，如圖8(b)所示，排 氣門搖臂56仍然抵接於排氣凸輪46，依照排氣凸輪a 之凸輪輪廓而使排氣門36開閉。 因此，藉由該減壓機構200亦使得僅在引擎起動時於引 擎1〇壓縮行程α巾打開排氣門36,由此降低引擎起動 1之壓縮壓力。因此，當引擎起動方式使用自起動方式 時，相較於不具備減壓機構者可採用小型自起動馬達， 又，當使用腳踏起動方式時，可降低引擎起動時所須之腳 踏力，可易於引擎起動。 、 本實施形態中，由於上述減壓機構2〇〇具備離心式調速 器100，於該離心式調速器100之滑件1〇1内周部與凸輪 軸50外周部之間配置對該滑件1〇1施壓的施壓構件、η、 故而與第1實施形態相同，可縮短減壓機構2〇〇之凸輪 軸方向之總長。 312ΧΡ/發明說明書(補件)/96-02/95140351 21 1323308 圈狀彈簧應用於配置於滑件81、1〇1内側之施壓構件％、 115之情況’然而亦可使用圈狀彈簧以外之施壓構件。 =L本實施形態中，例示有將本發明應用於二輪機車用 2單〉飞缸引擎的減壓機構之情況，亦可應用於具有多個氣 同之引擎之減壓機構，又，並不限於二輪機車使用，亦= 廣泛應用於分類為ATVUU-terrain vehicle，全地形車 的三輪車輛及四輪車輛等各種車輛之引擎的減壓機 圖式簡單說明】 圖 圖1係具備第1實施形態之減壓機構之引擎的側剖面 圖2係圖1之π — π剖面圖 圖3(a)係減壓機構之滑件的前視圖，（…係 圖，（c)係滑件之後視圖。 =(a)係減|機構之配重保持體的前視圖，⑸係配重 丨保持體之剖面圖，（c)係配重保持體之後視圖。 圖5(a)係表示弓丨擎起動時壓縮行程α中之減壓機構的 圖，⑻係表示引擎起動時其他步驟中之減壓機構的圖。 圖6(a)係表示引擎起動後壓縮行程〇中之減壓機構的 Θ 係表不引擎起動後其他步驟中之減壓機構的圖。 圖7係表示採用第2實施形態之減壓機構之引擎之一 分的剖面圖。 ° 引表：引擎起動時之壤構的圖，⑻係表示 5丨擎起動後之減壓機構的圖。 ! 12ΧΡ/辦月說明書(補件)/96-02/95140351 23 1323308Since the toothed structure of the teeth is combined, the shape of the parts can be prevented from being complicated, so that the pressure reducing mechanism can be simplified. Further, in the present configuration, since the centrifugal weight 82 is held between the slider 81 inserted by the cam shaft 5〇 and the weight holding body 83, a large diameter hole is provided on one end side of the cam shaft, and A guide group is disposed in the large diameter hole, and the decompression cam and the spring are disposed in the axial direction in the q-guide group, thereby being compared with the 312XP/invention specification (supplement)/96_〇2/9514() 351 in the circumference thereof 17 1323308 The outer weight of the outer shaft supports the centrifugal weight of the decompression cam. It will not require the shaft to support the centrifugal weight. Therefore, the number of parts and the mechanism can be further reduced, and the centrifugal weight is not required to be placed on the decompression cam. Around the outside, so - the pressure reducing mechanism can be reduced in diameter. - The pressure reducing mechanism 70 of the present configuration can reduce the size and weight of the overall shape. Therefore, by using the pressure reducing mechanism 7, it is possible to reduce the rotational load of the engine 10, the downsizing of the cylinder head 13, and the weight reduction around the cylinder head 13. (2) Second Embodiment Fig. 7 and Figs. 8(a) and 8(b) show a second embodiment. In this embodiment, the pressure reducing mechanism 200 of the centrifugal governor 100 is configured such that the centrifugal governor is disposed on the side of the exhaust cam 4 6 inside the slider ι 1 The pressing member 115 that presses the slider 1 〇 1 moves the slider i 〇丨 along the cam shaft 5 〇 toward the opposite side of the exhaust cam 46 when the engine 1 〇 is started. In the following description, components that are substantially the same as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 7, the centrifugal governor 1 includes a slider ι 1 which is inserted by the cam shaft 50 and freely movable in the axial direction of the cam shaft 5 ;; and a weight holding body 103, which A plurality of centrifugal weights (spherical) 8 2 are inserted between the cam shaft and the slider 1〇1. The slider 101 includes a substantially cylindrical tubular portion 1〇5, a sheath portion 1〇6 provided on one end side of the tubular portion 105, and a side opposite to the crotch portion of the tubular portion 1〇5. The decompression cam 丨〇7. The inner circumference of the cylindrical portion 5 of the decompression cam 1 〇7 side is formed to be the outer diameter with respect to the cam shaft 5〇, and the rotation of the 312XP/invention specification (supplement)/96_02/9514〇35] 1323308 The value of the same diameter is formed, and a groove portion 119A extending from the cylindrical portion (10) is formed, and the protruding end of the insertion cam shaft 50 and a glaze direction preventing member 11G is inserted into the groove portion U9A. _ pin (shift = member 101 is movably disposed in the axial direction of the cam shaft 5 ,, ^ ^ the latch pin 11 〇 prevents the slider 101 from approaching the circumference of the cam shaft 5 由 = by the tube 1 〇 5 The large diameter of the inner circumference of the inner circumference of the sleeve portion 106 side, whereby, as shown in Fig. 7, when the tubular portion 1〇5: is passed: the cam shaft 50, with the cam shaft 5〇, at #Π Between the ^ ^ ^ and e, there is a configuration 117 of the pressure applying structure 115. The pressing member 115 is, for example, a spring, and the pressing member 115 disposed in the arrangement gap 116 is connected to the arrangement gap U6. The inner wall portion m, the other end abuts;; = 2: the ring member 118 intervenes the slider m and the support cam shaft bearing decompression cam 107 has a fixed at 锊1nc, 1η7Δ Ώ U疋 on the 4 outer peripheral portions The ring member: and the cam portion fixed to the outer peripheral portion of the ring member, the ring member mA and the cam portion 107B may be integrally formed, or may be integrally formed with the slider 101. The body 103 has a substantially cylindrical body that allows the slider 1〇1 to be freely inserted. More specifically, the inner diameter has a rotational fit with respect to the ring member 107A fixed to the slider ι. The diameter 'and the opening portion through which the cam portion of the inserted slider ι is removed, and further includes the assembly of the pressure reducing mechanism 200 to the side portion 103C of the bearing 48 in a state in which the cam shaft 50 is inserted. First, insert the weight holder 1〇3 into the 312XP/invention manual (supplement)/96-02/95140351 19 (·1 1323308 After entering the camshaft 50, insert the slider ιοί into the camshaft 5〇 and Inserted into the weight holding body 103, secondly, after the pressing member 115 is inserted into the arrangement gap 116 of the slider 101, the ring member 118 is inserted into the cam shaft 50, whereby the pressure reducing mechanism 200 is assembled to the cam shaft 5 Next, the operation of the pressure reducing mechanism 200 will be described. Fig. 8(a) shows the pressure reducing mechanism 200 at the time of starting the engine, and Fig. 8(b) shows the pressure reducing mechanism 200 after the engine is started. 50 is rotated at a very low speed or the number of rotations is substantially zero. At this time, since the centrifugal force is hardly generated on the centrifugal weight 82, the slider 101 is moved toward the exhaust cam 46 side by the pressing force of the pressing member 115, by the Moving, the centrifugal weight 82 is along the sheath portion ι 6 of the slider 1〇1 The inclined portion 103C of the weight holding body 103 moves to the innermost circumferential side, and the sliding member 101 stops at a position that is abutted to the centrifugal weight 82 on the innermost circumferential side (hereinafter referred to as a first position). (a), the i-th position corresponds to the position of the decompression cam 107 disposed on the slider 1〇1 facing the arm portion 56a of the exhaust valve rocker arm 56. Therefore, when the engine 10 is In the case of the compression stroke α, as shown in Fig. 8(a), the decompression cam 107 push-up portion 87A pushes up the ejector rocker arm 56 integral with the arm portion 56A, thereby causing the exhaust valve rocker arm The self-venting cam 46 opens the exhaust valve 36 only by floating the gap. On the other hand, when the engine 1 is outside the compression stroke α, the upper portion 87 of the decompression cam 1 〇7 does not abut against the arm portion 56, and the exhaust valve rocker arm 56 abuts against the exhaust cam. The exhaust valve 36 is opened and closed according to the cam rim of the exhaust cam 46. Further, when the number of revolutions starts to increase at a very low speed from the camshaft 5〇 or the number of revolutions is zero, the state of the invention is increased, and the centrifugal force acting on the centrifugal weight 82 becomes large. The centrifugal force of the centrifugal weight 82 acts on the inclined portion i3C of the weight holding body 1 () 3 to thereby generate a force for moving the slider 101 to the opposite side of the exhaust cam 46 when the force exceeds the pressing member 115 When the pressure is applied, the sliding member ι is moved against the pressing force of the pressing member 115 toward the opposite side of the exhaust cam 46, whereby the slider 101 is moved to the abutting ring member 118 as shown in Fig. 8(b). Bit ^ is called the second position). This second position corresponds to a non-contact position where the decompression cam provided on the slider 1〇1 does not abut against the arm portion 56A of the exhaust valve rocker arm 56. Therefore, after the engine is started, even if the engine 10 is in any of the compression stroke α, the combustion step, the exhaust stroke, and the intake stroke, as shown in FIG. 8( b ), the exhaust valve rocker arm 56 is still abutted. The exhaust cam 46 opens and closes the exhaust valve 36 in accordance with the cam profile of the exhaust cam a. Therefore, the decompression mechanism 200 also opens the exhaust valve 36 at the engine 1 〇 compression stroke α only when the engine is started, thereby reducing the compression pressure of the engine start 1. Therefore, when the engine starting mode uses the self-starting mode, a small self-starting motor can be used compared to the case where the pressure reducing mechanism is not provided, and when the pedal starting mode is used, the pedaling force required for starting the engine can be reduced. Easy to start the engine. In the present embodiment, the pressure reducing mechanism 2 is provided with the centrifugal governor 100, and is disposed between the inner peripheral portion of the slider 1〇1 of the centrifugal governor 100 and the outer peripheral portion of the camshaft 50. The pressing members η which are pressed by the slider 1〇1 are the same as in the first embodiment, and the total length of the camshaft direction of the pressure reducing mechanism 2〇〇 can be shortened. 312ΧΡ/Invention Manual (Supplement)/96-02/95140351 21 1323308 The coil spring is applied to the case of the pressing members %, 115 disposed inside the sliders 81 and 1〇1, however, it is also possible to use a coil spring. Pressure member. In the present embodiment, the present invention is applied to a decompression mechanism of a two-wheeled > two-cylinder engine for a two-wheeled vehicle, and can also be applied to a decompression mechanism having a plurality of engines of the same type, and is not It is limited to the use of the two-wheeled vehicle, and is also widely used in the ATVUU-terrain vehicle, the three-wheeled vehicle of the ATV, and the engine of the four-wheeled vehicle. FIG. 2 is a side view of the engine of the pressure reducing mechanism, FIG. 3 is a front view of the sliding member of the pressure reducing mechanism, (...), and (c) is a rear view of the slider. = (a) is the front view of the weight-retaining body of the mechanism, (5) the cross-sectional view of the weight-retaining body, and (c) the rear view of the weight-holding body. Figure 5(a) shows the bowing engine start A diagram of the pressure reducing mechanism in the compression stroke α, and (8) is a diagram showing the pressure reducing mechanism in the other steps at the time of starting the engine. Fig. 6(a) is a diagram showing the pressure reducing mechanism in the compression stroke 引擎 after the engine is started. Figure of the decompression mechanism in other steps after the engine is started. Figure 7 shows the second actual use. A sectional view of one of the engines of the decompression mechanism of the form. ° The reference table: the map of the soil structure at the start of the engine, and (8) shows the diagram of the decompression mechanism after the start of the 5 engine. ! 12ΧΡ/月月手册(补Piece)/96-02/95140351 23 1323308
【主要元件符號說明】 10 引擎 11 曲轴箱 12 汽缸體 13 汽缸蓋 14 蓋罩 20 曲轴 20A 平衡配重 21 連桿 22 活塞 23 汽缸 26 螺栓 30 燃燒室 31 排氣口 32 進氣口 35 進氣門 36 排氣門 37 汽門彈簧 38 火星塞 40 動閥機構 41 汽門室 45 進氣凸輪 46 排氣凸輪 47、48 轴承 312XP/發明說明書(補件)/96-02/95140351 13.23308 88A 内周突出部 89A 槽部 90 、 110 卡止銷（移動阻止構件） 92 段差部 95 、 115 施壓構件 103B 開口 107A 環構件 107B 凸輪部 116 配置間隙 117 壁部 118 環構件 119A 槽部 C1 中心軸 DA 距離 Dl、D2 外徑 dl ' d2 ' d2 内徑 26 312XP/發明說明書(補件)/96-02/95140351[Main component symbol description] 10 Engine 11 Crankcase 12 Cylinder block 13 Cylinder head 14 Cover 20 Crankshaft 20A Balance weight 21 Connecting rod 22 Piston 23 Cylinder 26 Bolt 30 Combustion chamber 31 Exhaust port 32 Intake port 35 Intake valve 36 Exhaust valve 37 Valve spring 38 Mars plug 40 Dynamic valve mechanism 41 Valve chamber 45 Intake cam 46 Exhaust cam 47, 48 Bearing 312XP / Invention manual (supplement) / 96-02/95140351 13.23308 88A Inner circumference Portion 89A Groove portion 90, 110 Locking pin (moving preventing member) 92 Step portion 95, 115 Pressing member 103B Opening 107A Ring member 107B Cam portion 116 Arranging gap 117 Wall portion 118 Ring member 119A Groove portion C1 Center axis DA Distance Dl , D2 outer diameter dl ' d2 ' d2 inner diameter 26 312XP / invention manual (supplement) / 96-02/95140351