201018376 九、發明說明： *【發明所屬之技術領域】 本發明係涉及一種風扇，尤係涉及一種對電子元 熱之離心風扇。 【先前技術】 隨著電腦產業之迅速發展，CPU追求高速度化、高功 能化以及小型化所衍生之散熱問題越來越嚴重，這在筆呓 ❹型電腦等内部空間狹小之電子裝置中更為突出。如果無法 將CPU等電子元件所產生之熱量及時有效地散發出去，將 極大地影響電子元件之工作性能，同時還會縮短電子元件 之使用壽命，故必須對電子元件進行散熱。 ❿ 目前，業界常使用離心風扇對電子元件進行散熱，誃 離心風扇包括-底板、-蓋板、連接該底板與蓋板^一侧 壁以及收容於由底板、蓋板及侧壁所形成之收容空間内之 -葉輪。該侧壁上設有-出風口，該出風口具有—近風端 及與近風端相對之-遠風端，該側壁於靠近該遠風端處向 收容空間内突伸形成一舌口結構，該葉輪包括一輪轂及由 輪轂周緣向外呈放射狀延伸之複數扇葉。 *當該離心風扇工作時，該葉輪高速旋轉，該葉輪之扇 葉間之氣流在扇葉之驅動下隨葉輪一起旋轉，在離心力之 作用下’該扇葉間之氣流被拋向扇葉之自由末端其中該 扇葉之背風面上之邊界層氣流在靠近扇葉之自由末端時產 生剝離現象而與扇葉之背風面分離，從該背風面上分離之 201018376 氣流在扇葉之自由末端附近形成渦流，該渦流撞擊舌口結 構之表面從而產生渦流噪音。 【發明内容】 有鑒於此，有必要提供一種可降低噪音之離心風扇。 -種離心風扇，包括—底板、—蓋板、連接底板與蓋 板之一侧壁以及收容於由底板、蓋板及側壁所圍成之收容 空間内之一葉輪，該侧壁上設有一出風口，該出風口具有 〇 一近風端及與近風端相對之—遠風端，該葉輪包括複數放 射狀之扇葉，該葉輪運轉時產生之氣流自該遠風端經由側 壁之内表面流向近風端’該側壁於靠近該遠風端處設有一 正對該扇葉之多孔材料層，該側壁於多孔材料層所在之位 置處向收容空間内凸伸。 ❹ -種離心風扇’包括—底板、—蓋板、連接底板與蓋 ’之侧壁以及收容於由底板、蓋板及側壁所圍成之 容空間内之-葉輪，該侧壁上設有—出風口，該侧壁上 於靠近出風口之位置處形成一向收容空間内凸伸之“V” 形舌口結構’該舌口結構包括—正對該葉輪之多孔材料層。 與習知技術相比，本發明離心風扇十之側壁於靠近該 2 =處設-正對該扇葉之多孔材料層，該多孔材料層之 祖猶:表面可以減弱渦流之強许 "羽“之強度’並且可以對來自扇葉自由 之唾ί 到緩衝之作用，從而降低了離心風扇運轉時 【實施方式】 下面參照_結合實施例對本發明作進-步說明。 201018376 請參照圖1及圖2，該離心風扇包括一底座10、收容 於底座10中之定子（圖未示）與葉輪20以及蓋設於底座 10上之一蓋板30。 該葉輪20包括一輪轂21以及由輪轂21周緣向外呈放 射狀延伸之複數扇葉22。 該底座10包括一底板11以及由底板11之周緣向上一 體延伸之一侧壁12。該侧壁12連接於該上蓋30與該底板 11之間，該底板11、側壁12及蓋板30共同圍成一收容葉 輪20之收容空間40。該底板11及蓋板30之中間對應該葉 輪20之位置分別設有一進風口 111。該側壁12呈渦形，其 一侧設有與該進風口 111垂直之一出風口 121。在本實施例 中，該葉輪20沿逆時針方向轉動。該出風口 121具有一近 風端1211以及與該近風端1211相對之一遠風端1212，當 該離心風扇工作時，該葉輪20之扇葉22驅動氣流自遠風 端1212經由側壁12之内表面流向近風端1211。 該侧壁12於靠近該遠風端1212處向收容空間40内水 平凸伸形成一凸塊123,該凸塊123於水平方向上向收容空 間40凸伸之距離自凸塊123靠近遠風端1212之一端向遠 離遠風端1212之另一端先逐漸增加再逐漸減小，使該凸塊 123之表面大致呈“V”形。該凸塊123之表面包括遠離該 遠風端1212且朝向葉輪20之一第一表面1231以及靠近且 朝向該遠風端1212之一第二表面1232，該第一表面1231 與第二表面1232於凸塊123之中間平滑連接。該凸塊123 之表面緊密貼設一多孔材料層124,該多孔材料層124由多 201018376 孔材料製成，如海綿等。該多孔材料層124藉由膠粘物， 如AB膠等粘貼於該凸塊123之表面並正對該扇葉22。該 多孔材料層124為大致呈“V”形之條形片狀體，其自該凸 塊123靠近該遠風端1212之一端沿凸塊123之表面延伸至 該凸塊123遠離該遠風端1212之另一端，即該多孔材料層 124同時覆蓋該第一表面1231及第二表面1232。該多孔材 料層124與該凸塊123相對之一面與該凸塊123之表面形 狀相同，該多孔材料層124之高度與該凸塊123之高度相 同。該多孔材料層124中間之厚度均勻且小於該扇葉22之 自由末端到該凸塊123表面之最小距離，該多孔材料層124 兩端之厚度向多孔材料層124之外側逐漸變小，從而使該 多孔材料層124之兩末端分別與該側壁12之内表面平滑連 接。該凸塊123與該多孔材料層124共同形成一向收容空 間40凸伸之“V”形舌口結構120。 與習知技術中之離心風扇相比，本發明中之離心風扇 φ之舌口結構120由該凸塊123與該多孔材料層124共同構 成，該多孔材料層124之粗糙表面可以減弱該舌口結構120 表面之渦流之強度，並且該多孔材料層124可以對來自扇 葉22自由末端之氣流起到緩衝之作用，從而降低了離心風 扇運轉時氣流在舌口結構120處產生之噪音。 本發明中之離心風扇不限於上述設計，圖3所示為本 發明第二實施例中之離心風扇，與第一實施中之離心風扇 不同之處在於：該多孔材料層124a之水平截面為三角形， 該多孔材料層124a直接與該側壁12a結合，形成從該侧壁 201018376 12a向收容空間40内凸伸之一 “V”形舌口結構120a。 綜上所述，本發明符合發明專利之要件，爰依法提出 專利申請。惟以上所述者僅為本發明之較佳實施例，舉凡 熟悉本案技藝之人士，在爰依本發明精神所作之等效修飾 或變化，皆應涵蓋於以下之申請專利範圍内。 【圖式簡單說明】 圖1為本發明第一實施例中之離心風扇之立體分解圖。 圖2為圖1所示離心風扇之底座之俯視圖。 圖3為本發明第二實施例中之離心風扇之立體分解圖。 【本發明主要元件符號說明】 底座 10 底板 11 進風口 111 侧壁 12、 12a 舌口結構 120、 120a 出風口 121 近風端 1211 遠風端 1212 凸塊 123 第一表面 1231 第二表面 1232 多孔材料層 124、 124a 轉子 20 輪轂 21 扇葉 22 蓋板 30 收容空間 40201018376 IX. Description of the invention: * [Technical field to which the invention pertains] The present invention relates to a fan, and more particularly to a centrifugal fan for electronic heat. [Prior Art] With the rapid development of the computer industry, the heat dissipation problem derived from the pursuit of high speed, high functionality, and miniaturization of the CPU is becoming more and more serious, which is more in an electronic device with a small internal space such as a pen-type computer. To stand out. If the heat generated by electronic components such as the CPU cannot be dissipated in a timely and effective manner, the performance of the electronic components will be greatly affected, and the life of the electronic components will be shortened. Therefore, the electronic components must be dissipated. ❿ At present, the industry often uses a centrifugal fan to dissipate heat from electronic components. The centrifugal fan includes a bottom plate, a cover plate, a side wall connecting the bottom plate and the cover plate, and a receiving body formed by the bottom plate, the cover plate and the side wall. The impeller in the space. An air outlet is disposed on the side wall, and the air outlet has a near wind end and a windward end opposite to the near wind end, and the side wall protrudes into the receiving space to form a tongue opening structure near the far wind end. The impeller includes a hub and a plurality of blades extending radially outward from the periphery of the hub. * When the centrifugal fan is working, the impeller rotates at a high speed, and the airflow between the blades of the impeller rotates with the impeller under the driving of the blade, and the airflow between the blades is thrown to the blade by the centrifugal force. The free end is where the boundary layer airflow on the leeward side of the blade is peeled off near the free end of the blade and is separated from the leeward side of the blade, and the 201018376 airflow separated from the leeward is near the free end of the blade A vortex is formed which strikes the surface of the tongue structure to create eddy current noise. SUMMARY OF THE INVENTION In view of the above, it is necessary to provide a centrifugal fan that can reduce noise. a centrifugal fan comprising: a bottom plate, a cover plate, a side wall of the connecting bottom plate and the cover plate, and an impeller housed in the receiving space surrounded by the bottom plate, the cover plate and the side wall, wherein the side wall is provided with an out a tuyere having a near-wind end and a near-wind end opposite to the near-wind end, the impeller includes a plurality of radial blades, and the airflow generated by the impeller is generated from the far end via the inner surface of the side wall Flowing toward the near-wind end, the side wall is provided with a porous material layer facing the blade near the windward end, and the side wall protrudes into the receiving space at a position where the porous material layer is located. ❹ - a centrifugal fan 'including a bottom plate, a cover plate, a side wall connecting the bottom plate and the cover', and an impeller housed in a space surrounded by the bottom plate, the cover plate and the side wall, the side wall is provided with - In the air outlet, the side wall is formed at a position close to the air outlet to form a "V" shaped tongue structure protruding into the receiving space. The tongue opening structure comprises a porous material layer facing the impeller. Compared with the prior art, the side wall of the centrifugal fan of the present invention is disposed near the 2 = - the porous material layer of the blade, the ancestors of the porous material layer: the surface can weaken the strong eddy current "Strength" and can act on the buffer from the freeness of the fan blade, thereby reducing the operation of the centrifugal fan. [Embodiment] The present invention will be further described with reference to the accompanying embodiment. 201018376 Please refer to FIG. 2, the centrifugal fan includes a base 10, a stator (not shown) and an impeller 20 housed in the base 10, and a cover plate 30 disposed on the base 10. The impeller 20 includes a hub 21 and a hub 21 The plurality of blades 22 extending radially outwardly from the periphery. The base 10 includes a bottom plate 11 and a side wall 12 extending integrally from the periphery of the bottom plate 11. The side wall 12 is connected between the upper cover 30 and the bottom plate 11. The bottom plate 11, the side wall 12 and the cover plate 30 together form a receiving space 40 for receiving the impeller 20. The bottom plate 11 and the cover plate 30 are respectively provided with an air inlet 111 corresponding to the position of the impeller 20. The side wall 12 is vortexed. Shape, one side There is an air outlet 121 perpendicular to the air inlet 111. In the embodiment, the impeller 20 rotates in a counterclockwise direction. The air outlet 121 has a near wind end 1211 and a wind far from the near wind end 1211. The end 1212, when the centrifugal fan is in operation, the fan blade 22 of the impeller 20 drives the airflow from the far wind end 1212 to the near air end 1211 via the inner surface of the side wall 12. The side wall 12 is received near the far wind end 1212. A protrusion 123 is formed in the space 40 to form a protrusion 123. The distance from the protrusion 123 to the receiving space 40 in the horizontal direction is gradually increased from the one end of the protrusion 123 near the far wind end 1212 to the other end away from the far wind end 1212. Further decreasing, the surface of the bump 123 is substantially "V" shaped. The surface of the bump 123 includes a first surface 1231 away from the windward end 1212 and toward the impeller 20 and toward and toward the far wind end. A second surface 1232 of the 1212, the first surface 1231 and the second surface 1232 are smoothly connected in the middle of the bump 123. The surface of the bump 123 is closely attached with a porous material layer 124, and the porous material layer 124 is 201018376 Made of hole material, such as sponge. The porous material layer 124 is adhered to the surface of the bump 123 by a glue such as AB glue or the like and faces the blade 22. The porous material layer 124 is a strip-shaped body having a substantially "V" shape, and The porous material layer 124 covers the first surface 1231 and the first surface 121 from the surface of the bump 123 near the end of the bump 123 to the other end of the bump 123 away from the far wind end 1212. The surface of the porous material layer 124 and the surface of the bump 123 are the same as the surface of the bump 123. The height of the porous material layer 124 is the same as the height of the bump 123. The thickness of the porous material layer 124 is uniform and smaller than the minimum distance from the free end of the fan blade 22 to the surface of the bump 123, and the thickness of both ends of the porous material layer 124 gradually becomes smaller toward the outer side of the porous material layer 124, thereby Both ends of the porous material layer 124 are smoothly connected to the inner surface of the side wall 12, respectively. The bumps 123 and the porous material layer 124 together form a "V" shaped tongue-and-groove structure 120 that projects toward the receiving space 40. Compared with the centrifugal fan in the prior art, the tongue structure 120 of the centrifugal fan φ of the present invention is formed by the bump 123 and the porous material layer 124, and the rough surface of the porous material layer 124 can weaken the tongue. The strength of the vortex on the surface of the structure 120, and the layer of porous material 124 can buffer the flow from the free end of the blade 22, thereby reducing the noise generated by the airflow at the tongue and mouth structure 120 during operation of the centrifugal fan. The centrifugal fan in the present invention is not limited to the above design, and FIG. 3 shows a centrifugal fan according to a second embodiment of the present invention, which is different from the centrifugal fan in the first embodiment in that the horizontal section of the porous material layer 124a is a triangle. The porous material layer 124a is directly joined to the side wall 12a to form a "V" shaped tongue-and-groove structure 120a projecting from the side wall 201018376 12a into the receiving space 40. In summary, the present invention complies with the requirements of the invention patent, and proposes a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view of a centrifugal fan in a first embodiment of the present invention. 2 is a top plan view of the base of the centrifugal fan shown in FIG. 1. Fig. 3 is an exploded perspective view showing the centrifugal fan in the second embodiment of the present invention. [Description of main components of the present invention] Base 10 Base plate 11 Air inlet 111 Side wall 12, 12a Tongue structure 120, 120a Air outlet 121 Near wind end 1211 Far wind end 1212 Bump 123 First surface 1231 Second surface 1232 Porous material Layer 124, 124a Rotor 20 Hub 21 Blade 22 Cover 30 Containing space 40