200809082 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種引擎冷卻結構，尤指一種適用於強 制空冷式引擎冷卻結構。 5 【先前技術】 對於一般車輛而言，其引擎必須設計有冷卻結構以使 引擎不致於產生過熱情形，而可以因此使引擎持續正常運 作。 10 一般引擎之冷卻結構可分為空（氣）冷式與水冷式，而 空（氣）冷式又可分為強制空冷與自然空冷二種，差別在於強 制二冷係以一冷卻風扇強制吸入（導入）外部空氣以對引擎 進行冷卻，而自然空冷則是使外部空氣自然流入以對引擎 進行冷卻。 15 請參閱圖1係習知強制空冷式引擎之立體圖，其包括有 一 缸體91、一導風罩92、以及一冷卻風扇93。其中，導 風罩92係引導由冷卻風扇93所吸入（導入）之外部空氣流動 至缸體91 ’並對汽缸體91進行散熱冷卻。 然而，由於汽缸體91具有相對高溫與相對低溫等區 20 域，而冷卻風扇93所吸入之外部空氣係整個對汽缸體91之 相對局溫與相對低溫區域進行散熱冷卻，故容易造成散熱 不均等現象，且外部空氣流動至汽缸體91時，汽缸體91會 形成一迎風面911，外部空氣則衝擊此迎風面911而造成能 量損失，故亦會影響汽缸體91之散熱冷卻效果。 5 200809082 請參閲圖2係習知另一強制空冷式引擎之立體圖，盆主 要結構皆與上述習知強制空冷式引擎相同，唯差別在^將 導風罩94做-設計上之變更，亦即於導風罩料之内側面941 再設有複數個導風板942，而此複數個導風板942係依照汽 5缸體95之散熱鰭片951之方向而設計，故可引導外部空氣之 流動以避免亂流。 然而，導風罩94之導風板942與汽缸體％之散熱鰭片 951必須互相配合設計，才可達到引導外部空氣流動以避免 亂流之目的，例如，散熱轉片951必須配合導風板—而設 丄〇収傾斜狀、或曲面狀、或其他形狀、或其他角度等，作 前述之設計方式則容易造成散熱鰭片951製造不易、影響汽 缸體95之散熱冷卻效果等問題。 因此，不論是圖1或圖2之習知強制空冷式引擎，皆合 造成汽缸體9丨，95產生散熱不均或散熱效果不佳、或外部^ b氣衝擊汽缸體91，95之迎風面而造成損失等問題，且若嚴^ 的話，會造成汽缸體91，95產生變形而使其壽命減短，故 十分理想。 【發明内容】 μ本發明係可使冷卻風扇所導人之外部空氣對汽缸體進 ^散熱冷卻時，不會因為衝擊汽缸體而產生能量損失之問 題’故可有效對汽紅體進行散熱冷卻，並因此使汽叙體之 溫度可以均勻分佈。 6 200809082 =外，本發明係能於w響汽㈣之設計與製造下， 有效對汽缸體進行散熱冷卻，並因 可以均勻分佈。 股里度 f此，本發明之強制空冷式引擎冷卻結構包括一汽缸 小一冷：風扇、以及-導風罩。其中，汽缸體包括有至 ^目對高溫區、以及至少一相對低溫區，且導風罩係連 通汽缸體與冷卻風扇。 罩係連 10 15 一、上述之導風罩圍繞有一導風通路，此導風通路包括有 進風口、以及一開口，其中之進風口係對應於冷卻風扇， ^ 口係對應於汽缸體，且導風罩並包括有至少_分隔板， /、係分隔導風通路並形成至少二通風流道。 本發明之特色在於上述導風罩之至少二通風流道之其 了之係對應於汽缸體之至少一相對高溫區，導風罩之至 '、通風⑺L道之另一係對應於汽缸體之至少一相對低溫 區。 士因此，藉由上述結構，冷卻風扇吸入（導入）外部空氣 寸可藉由導風罩分隔板之分隔作用，調配每一通風流道 之二氣流量，例如，某一通風流道具有較大之空氣流量而 可對/气紅體之相對高溫區進行散熱冷卻，反之，某一通風 冰道具有較小之空氣流量而可對汽缸體之相對低溫區進行 散熱冷卻。 故藉由導風罩分隔板之分隔、與調配空氣流量之作 用’當外部空氣導入後，可避免此外部空氣直接衝擊汽缸 體而造成能量損失，而因此可使外部空氣有效對汽紅體進 7 200809082 行散熱冷卻，使汽缸體之溫度可以均句分佈，同時 分隔板之調配空氣流量作用，亦可使外部空氣之氣流^ 流動，而不會產生擾流之現象。 、1、 再者，上述之結構僅需設計分隔板即可， :體與分隔板搭配設計，亦即上述之結構可於不影 下，仍可有效對汽_進行散熱冷二吏 /飞虹體之溫度可以均勻分佈。 上述導風罩之分隔板可橫向分隔導風 分隔導風通路、戋可辦知八碎此士 4 4 Γ縱向 向分隔導風通路9力Α板之數量而同時以橫向與縱 上述之汽虹體包括有至少一散熱韓片，且至少— ::了與至少一散熱鰭片呈交錯狀、或至少-分隔板 兵至少一散熱鰭片呈非交錯狀等。 ’、 15 20 【實施方式】 請參閱圖3係本發明第一較佳每 擎之立體圖，i中顯干太二例之強制空冷式引 式引擎姓椹七权 x月弟—較佳實施例之強制空冷 式弓|冬冷部結構包括有一汽、 導風罩3。 々口 P風扇2、以及一 圖式中之 紅體1包括有一相古 相對形成-相對低〜12日，對心區U，其他部位則 散執錄片13日 此汽l卜週凸料複數個 t例中，前述之狂體1包括有-汽缸1〇1、以及一汽 碩102,且汽缸頭102係組設於汽缸1〇1上。 8 200809082 此外，導風罩3係連通汽缸體丨與冷卻風扇2，且導風罩 3圍繞有一導風通路31，此導風通路31包括有一進風口 311、以及一開口 312，其中之進風口3u係對應於冷卻風扇 2，開口 312係對應於汽缸體〗，且此導風罩3並包括有二分 5 隔板32，此二分隔板32係分隔導風罩3之導風通路31、並因 此形成三個通風流道321，322,323。 於本實施例中，冷卻風扇2係為一離心式冷卻風扇，且 導風罩3之二分隔板32係橫向分隔導風罩3之導風通路31、 並因此形成上述之三個通風流道321，322,323，同時，導風 10罩3之二分隔板32係與汽缸體丨之複數個散熱鰭片 狀(略微垂直)。 又錯 另外，於本實施例中，導風罩3之二分隔板32係皆分別 延伸至進風口 311，並將進風口 311分別分隔成三個入口 3〇1，30253()3，此三個人口 3()1，3()2,3()3分別即是上述三個通 15風流道321，322,323之入口 301，302,303。同樣的，導風罩3 之二分隔板32亦皆分別延伸至開口 312，並將開口 312分別 分隔成二個出口 3〇4,3〇5,3〇6，而此三個出口 3〇4,3〇5,3㈧則 分別是三個通風流道321，322,323之出口 3〇4,3〇5,3〇6 上述結構之特色在於導風罩3之三個通風流道 20 321，322,323、其中至少一個係對應於汽缸體1之相對高溫區 11、又其中至少一個係對應於汽缸體1之相對低溫區12。 詳而言之，汽缸體丨之相對高溫區u於本實施例中係為 其排乳道（如圖3所示）之部位，而此處即需大量之外部空氣 對其進行散熱冷卻。因此，利用導風罩3分隔板32之分隔作 200809082 用，當冷卻風扇2吸入（導入）外部空氣時，可利用較大面積 之入口 303調配大量之外部空氣、並使大量之外部空氣經: 通風流道323流動、並由出口3〇6流出，以對汽紅體】之相對 高温區11(減道之部位）奸«冷卻L提高此部位 5 之散熱冷卻效果。 再者，汽紅體1外側具有一迎風面14，故當冷卻風扇2 吸=(導人）外部线時’可彻較小面積之人n3Q2調配較 少量之外部空氣、並使較少量之外部空氣、經由通風流道您 流動、並由具有較大面積之出口 3〇5流出，&外部空氣對於 1〇汽缸體1迎風面14之衝擊即可減小，藉以避免外部空氣之能 又，汽缸體1除了相對高溫區丨丨（排氣道之部位）之外， 其他部位係為相對低溫區12，於本實施例中，才目對低 ⑵系以其進氣道（如圖3所示）之部位作為說明，而此處即; 15較少量之外部空氣對其進行散熱冷卻。因此，利用導風罩3 刀板32之分隔作用，當冷卻風扇2吸入（導入）外部空氣 時，可利用較小面積之入口 3〇1(比入口 3〇3面積小、比入口 302面積大）調配稍微大量之外部空氣、並使外部空氣經由 通風流道321流動、並由出口 3〇4流出，卩對汽缸體i之相對 20低溫區12(進氣道之部位）進行散熱冷卻。 古^於本實施例中，係以汽缸體丨之排氣道之部位作為相對 π» /凰區1以汊缸體1之進氣道之部位作為相對低溫區丨之作 為說明，而利用分隔板32之分隔、舆外部空氣流量調配之 作用對汽叙體1之相對高溫區1與相對低溫區i 2進行散熱 10 200809082 之然燒室（圖未示）具有較高溫度，故可利用分^板32 调配較大量之外部空氣對此處進行散熱冷卻，亦即^見、、， 缸體1不同部位之發熱及散 4 同流量之外部空氣。”、、之而纟制分隔板32調配不 10 15 20 口此’藉由導風罩3分隔板32之分隔、與調配空 =，當外部空氣導入後，可避免此外部空氣直接衝擊 ，飞-之迎風面14而造成能量損失，❿因此可使外部空氣 有效對汽紅體i進行散熱冷卻，使汽缸體k溫度可以均句 刀佈’同時’藉由分隔板32之調配空氣流量作用，亦可使 外部空氣之氣流順暢流動’而不會產生擾流之現象。 卜再者，上述之結構僅需設計分隔板32即可，並不需使 汽缸體U之散熱鰭片13)與分隔板32搭配設計，亦即上=之 結構可於不影響汽缸體1 (之散熱鰭片13)之設計與製造下， 仍可有效對汽缸體〗進行散熱冷卻，使汽缸體〗之溫度可以 均勻分佈。 請參閱圖4係本發明第二較佳實施例之強制空冷式引 擎之導風罩之立體圖，其主要結構皆與上述第一較佳實施 例相同’唯差別在於將導風罩4之分隔板42分別縱向分隔導 風罩4之導風通路41、並因此使導風通路41形成四個通風流 逼421，422,423,424，且分隔板42係與汽缸體1(請參閱圖2) 之散熱鰭片13(請參閱圖2)呈非交錯狀（略微平行），而此設 計方式同樣可視不同之發熱及散熱之需求，利用分隔板42 11 200809082 調配不同流量之外韶命々 實施例所述之各種功：乳，亦即同樣可達成上述第-較佳 請參閱圖5係本發明笛= 擎之導風罩之立體圓，复主==實=例之強制空冷α 例、與第二較佳實施似：冓白舆上述第-較佳實施 、1相同，唯差別在於導風罩5同時呈有 杈向分隔板52與縱向分隔柘 寸八有 隔導風通路51，此”方U兩種，並同時橫向與縱向分 求，利用橫向分隔板Hi熱〜 部空氣，亦即同樣可達成=福板53調配不同流量之外 ^ ^ A 達成上述弟一較佳實施例、盥第-較 佳貫施例所述之各種功效。 /、弟~車乂 上述貝&例僅係為了方便說明而舉例而已，本發明所 於上述實施例。“專利範圍所述為準，而非僅限 15 20 【圖式簡單說明】 圖1係習知強制空冷式引擎之立體圖。 圖2係習知另一強制空冷式引擎之立體圖。 擎之立體圖。 引擎之導風罩 圖3係本發明第一較佳實施例之強制空冷式引 圖4係本發明第二較佳實施例之強制空冷式 之立體圖。 之導風罩 圖5係本發明第三較佳實施例之強制空冷式引擎 之立體圖。 【主要元件符號說明】 12 200809082 汽缸體1 汽缸101 汽缸頭102 相對南溫區11 相對低溫區12 散熱鰭片13 迎風面14 冷卻風扇2 導風罩3 入口 301 入口 302 入口 303 5 出口 304 出口 305 出口 306 導風通路3 1 進風口 3 11 開口 312 分隔板3 2 通風流道321 通風流道322 通風流道323 導風罩4 導風通路41 分隔板42 通風流道421 通風流道422 10 通風流道423 通風流道424 導風罩5 導風通路5 1 橫向分隔板52 縱向分隔板53 13200809082 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to an engine cooling structure, and more particularly to a cooling structure for a forced air-cooled engine. 5 [Prior Art] For a general vehicle, the engine must be designed with a cooling structure so that the engine does not cause overheating, and thus the engine can continue to operate normally. 10 The cooling structure of general engine can be divided into air (air) cooling and water cooling, while air (air) cooling can be divided into forced air cooling and natural air cooling. The difference is that the forced cooling is forced by a cooling fan. The outside air is (introduced) to cool the engine, while the natural air cooling is to let the outside air flow naturally to cool the engine. 15 is a perspective view of a conventional forced air-cooled engine including a cylinder 91, an air hood 92, and a cooling fan 93. Here, the air hood 92 guides the outside air sucked (introduced) by the cooling fan 93 to the cylinder 91' and cools and cools the cylinder block 91. However, since the cylinder block 91 has a relatively high temperature and a relatively low temperature region 20, and the external air sucked by the cooling fan 93 cools and cools the relative local temperature and the relatively low temperature region of the cylinder block 91, it is easy to cause uneven heat dissipation. When the external air flows to the cylinder block 91, the cylinder block 91 forms a windward surface 911, and the outside air impacts the windward surface 911 to cause energy loss, which also affects the heat dissipation and cooling effect of the cylinder block 91. 5 200809082 Please refer to FIG. 2 is a perspective view of another forced air-cooled engine. The main structure of the basin is the same as the above-mentioned forced air-cooled engine, except that the difference is in the design of the air hood 94. That is, a plurality of air guiding plates 942 are further disposed on the inner side surface 941 of the air guiding hood, and the plurality of air guiding plates 942 are designed according to the direction of the heat radiating fins 951 of the steam 5 cylinder 95, so that the outside air can be guided. Flow to avoid turbulence. However, the air deflector 942 of the air duct 94 and the heat sink fins 951 of the cylinder block must be designed to cooperate with each other in order to guide the external air flow to avoid turbulence. For example, the heat sink fin 951 must cooperate with the air deflector. - The slanting shape, the curved shape, or other shapes, or other angles are provided, and the above-described design method is likely to cause problems such as difficulty in manufacturing the heat dissipation fin 951 and affecting the heat dissipation and cooling effect of the cylinder block 95. Therefore, whether it is the conventional forced air-cooled engine of FIG. 1 or FIG. 2, the cylinder block 9丨, 95 causes uneven heat dissipation or poor heat dissipation effect, or external wind impacts the windward surface of the cylinder block 91, 95. If the problem is caused by the loss, if the cylinder block 91, 95 is deformed and the life is shortened, it is ideal. SUMMARY OF THE INVENTION The present invention enables the external air of a cooling fan to be cooled and cooled to the cylinder block without causing energy loss due to impact on the cylinder block, so that the steam red body can be effectively cooled and cooled. And thus the temperature of the autoclave can be evenly distributed. 6 200809082 = In addition, the present invention is capable of effectively cooling and cooling the cylinder block under the design and manufacture of the w-steam (four), and can be evenly distributed. In this case, the forced air-cooled engine cooling structure of the present invention includes a cylinder of small one cooling: a fan, and an air hood. Wherein, the cylinder block includes a high temperature zone and at least a relatively low temperature zone, and the air hood is connected to the cylinder block and the cooling fan. The cover lining 10 15 a, the air hood is surrounded by an air guiding passage, the air guiding passage includes an air inlet, and an opening, wherein the air inlet corresponds to the cooling fan, and the air inlet corresponds to the cylinder block, and The air hood includes at least a partitioning plate, and is configured to separate the air guiding passages and form at least two ventilation flow passages. The invention is characterized in that at least two ventilation passages of the air guiding hood correspond to at least one relatively high temperature region of the cylinder block, and the other portion of the air hood to the air duct (7) corresponds to the cylinder block. At least one relatively low temperature zone. Therefore, with the above structure, the cooling fan sucks (introduces) the external air volume by the separation function of the air deflector partition plate, and the two air flow rate of each ventilation flow path is adjusted, for example, a certain ventilation flow path has a larger one. The air flow rate can be used to dissipate heat in the relatively high temperature region of the gas red body. Conversely, a certain air passage has a small air flow rate to cool and cool the relatively low temperature region of the cylinder block. Therefore, by the separation of the air deflector partition plate and the effect of the air flow distribution, when the external air is introduced, the external air can be directly impacted on the cylinder block to cause energy loss, thereby making the external air effective against the vapor red body. In 7 200809082, the heat dissipation of the cylinder allows the temperature of the cylinder block to be evenly distributed. At the same time, the air flow of the partition plate can also make the air flow of the external air flow without disturbing. 1. In addition, the above structure only needs to design the partition plate. The body and the partition plate are designed together, that is, the above structure can be used without any shadow, and the heat can be effectively cooled. The temperature of the flying rainbow body can be evenly distributed. The partitioning plate of the air guiding hood can laterally separate the air guiding and separating the air guiding passage, and the number of the vertical slabs of the windshield can be determined by the lateral direction and the vertical steam. The rainbow body includes at least one heat sinking film, and at least - :: is staggered with at least one heat sink fin, or at least - the at least one heat sink fin of the board is non-staggered. ', 15 20 [Embodiment] Please refer to FIG. 3 is a perspective view of the first preferred per-engineer of the present invention, and the forced air-cooled pilot engine of the second example of the present invention is the same as the preferred embodiment. The forced air-cooled bow|the structure of the winter cold section includes a steam and an air hood 3. The mouthpiece P fan 2, and the red body 1 in the figure include a phase relative to the formation - relatively low ~ 12 days, to the heart zone U, other parts are scattered recordings 13 days this steam l week convex mass In the example of t, the foregoing mad body 1 includes a cylinder 1 〇 1 and a hopper 102, and the cylinder head 102 is assembled on the cylinder 1 〇 1 . 8 200809082 In addition, the air guiding hood 3 is connected to the cylinder block and the cooling fan 2, and the air guiding hood 3 surrounds an air guiding passage 31. The air guiding passage 31 includes an air inlet 311 and an opening 312, wherein the air inlet 3u corresponds to the cooling fan 2, the opening 312 corresponds to the cylinder block, and the air hood 3 includes two partitions 5 and 32, and the two partitions 32 separate the air guiding passage 31 of the air guiding hood 3, and Thus, three ventilation passages 321, 322, 323 are formed. In the present embodiment, the cooling fan 2 is a centrifugal cooling fan, and the two partition plates 32 of the air guiding hood 3 are laterally partitioning the air guiding passage 31 of the air guiding hood 3, and thus forming the above three ventilation passages. 321,322,323, at the same time, the guide 10 of the guide 10 is divided into a plurality of fins (slightly perpendicular). In addition, in the present embodiment, the two partition plates 32 of the air hood 3 respectively extend to the air inlet 311, and the air inlet 311 is divided into three inlets 3〇1, 30253()3, respectively. The populations 3() 1, 3() 2, 3() 3 are the entrances 301, 302, 303 of the above three through 15 wind passages 321, 322, 323, respectively. Similarly, the two partition plates 32 of the air hood 3 also extend to the opening 312, respectively, and the openings 312 are respectively divided into two outlets 3〇4, 3〇5, 3〇6, and the three outlets 3〇4 3〇5,3(8) are the outlets of the three ventilation channels 321,321,323 respectively 3〇4,3〇5,3〇6 The above structure is characterized by three ventilation channels 20 321,322,323 of the air duct 3, At least one of them corresponds to the relatively high temperature zone 11 of the cylinder block 1, and at least one of them corresponds to the relatively low temperature zone 12 of the cylinder block 1. In detail, the relatively high temperature region u of the cylinder block is the portion of the faucet (shown in Fig. 3) in this embodiment, and a large amount of external air is required for heat dissipation. Therefore, the partition of the partition plate 32 by the air hood 3 is used as 200809082. When the cooling fan 2 sucks in (introduces) the outside air, a large area of the inlet 303 can be used to prepare a large amount of external air, and a large amount of external air is passed through. : The ventilation flow passage 323 flows and flows out from the outlet 3〇6 to increase the cooling and cooling effect of the portion 5 in the relatively high temperature region 11 (the portion of the reduction lane) of the vapor red body. Furthermore, the outside of the vapor red body 1 has a windward surface 14, so when the cooling fan 2 sucks (conducts) the external line, the smaller area of the person n3Q2 can be equipped with a smaller amount of outside air, and a smaller amount The outside air, which flows through the ventilation channel, flows out from the outlet 3〇5 with a large area, and the external air can reduce the impact on the windward side 14 of the cylinder block 1 to avoid the external air energy. Moreover, the cylinder block 1 is a relatively low temperature zone 12 except for the relatively high temperature zone (the portion of the exhaust passage). In the present embodiment, the low (2) system is used for its intake port (as shown in the figure). The part shown in 3) is explained, and here is 15; a small amount of external air is used for heat dissipation and cooling. Therefore, by the partitioning action of the air deflector 3 blade 32, when the cooling fan 2 sucks in (introduces) the outside air, the inlet 3〇1 of a smaller area can be utilized (the area smaller than the inlet 3〇3 and larger than the inlet 302 area) A small amount of external air is dispensed, and the outside air flows through the ventilation flow path 321 and flows out through the outlet 3〇4, and heat-cools the relative low temperature region 12 (the portion of the intake port) of the cylinder block i. In the present embodiment, the portion of the exhaust passage of the cylinder block is used as the relative π» / huang district 1 as the relatively low temperature region of the intake port of the cylinder block 1, and the utilization is used. The partitioning of the partition 32 and the external air flow distribution function to dissipate heat from the relatively high temperature zone 1 and the relatively low temperature zone i 2 of the steam navigator 1 200809082. The combustion chamber (not shown) has a relatively high temperature, so that it can be utilized. The panel 32 is equipped with a larger amount of external air to cool and cool the air, that is, the heat of different parts of the cylinder 1 and the outside air of the same flow rate. ”,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, , the fly-to-wind surface 14 causes energy loss, so that the external air can effectively cool the vapor red body i, so that the temperature of the cylinder block k can be equal to the same time. The flow can also make the flow of the external air flow smoothly without disturbing the flow. Moreover, the above structure only needs to design the partition plate 32, and the heat sink fin of the cylinder block U is not required. 13) Designed in conjunction with the partition plate 32, that is, the structure of the upper= can effectively cool and cool the cylinder block without affecting the design and manufacture of the cylinder block 1 (the heat radiating fin 13), so that the cylinder block 4 is a perspective view of the air hood of the forced air-cooled engine according to the second preferred embodiment of the present invention, the main structure of which is the same as the first preferred embodiment described above. The partition plates 42 of the air hood 4 are vertically separated The air guiding passage 41 of the air guiding hood 4, and thus the air guiding passage 41 forms four ventilation flow forces 421, 422, 423, 424, and the partitioning plate 42 is coupled with the heat dissipating fins 13 of the cylinder block 1 (please refer to FIG. 2) (please Referring to Figure 2), it is non-staggered (slightly parallel), and this design method can also be used to different heat and heat dissipation requirements. The partition plate 42 11 200809082 can be used to formulate various functions described in the examples. Milk, that is, the above-mentioned first-best is also possible. Please refer to FIG. 5, which is a three-dimensional circle of the hood of the present invention, which is a forced air-cooling α example of the present invention, which is similar to the second preferred embodiment.冓白舆 The above-mentioned preferred embodiment, 1 is the same, except that the air hood 5 is simultaneously provided with a slanting partitioning plate 52 and a longitudinally spaced apart air passage 51, which is a square U. At the same time, the horizontal and vertical divisions are utilized, and the horizontal partition plate Hi is used to heat up the air, that is, the same can be achieved. Various effects as described in the examples. /, 弟~车乂 The above-mentioned shell & examples are merely examples for convenience of explanation, and the present invention is applied to the above embodiments. "The scope of patents shall prevail, not limited to 15 20 [Simplified illustration of the drawings] Figure 1 is a perspective view of a conventional forced air-cooled engine. Figure 2 is a perspective view of another forced air-cooled engine. FIG. 3 is a perspective view of a forced air-cooling type according to a second preferred embodiment of the present invention. FIG. 5 is a third perspective view of the present invention. A perspective view of a forced air-cooled engine of the preferred embodiment. [Description of main components] 12 200809082 Cylinder block 1 Cylinder 101 Cylinder head 102 Relative south temperature zone 11 Relatively low temperature zone 12 Heat sink fin 13 Windward side 14 Cooling fan 2 Air hood 3 inlet 301 inlet 302 inlet 303 5 outlet 304 outlet 305 outlet 306 air guiding passage 3 1 air inlet 3 11 opening 312 partitioning plate 3 2 ventilation flow path 321 ventilation flow path 322 ventilation flow path 323 air hood 4 air guiding path 41 Partition plate 42 Ventilation channel 421 Ventilation channel 422 10 Ventilation channel 423 Ventilation channel 424 Air duct 5 Air duct 5 1 Horizontal partition 52 Longitudinal partition 53 13