1284716 九、發明說明： 【發明所屬之技術領域】 本發明涉及一種流體動壓軸承，尤其涉及一種流體動壓軸承的動 壓發生槽結構。 【先前技術】 近年來，流體動壓轴承在小型馬達如風扇馬達或磁碟機馬達的使 用上逐漸增加。流體動壓軸承是藉由油膜在軸心與轴承之間建立壓 力，使轴承與轴心分離，防止兩者間的磨損。通常於轴承内壁或軸心 外壁刻有魚骨狀的動壓發生槽，潤滑油集中於動壓發生槽内部，沿該 動壓發生槽建立壓力。加工魚骨狀的動壓發生槽一般需要將刀具伸進 軸承内孔進行切削或擠壓，以形成構槽。當電子產品逐漸微型化，轴 承内孔越來越小，在轴承内孔中加工這種魚骨狀的動壓發生槽將雙得 非常困難。而且，隨著陶瓷技術的發展，陶瓷材料在動壓軸承中亦有 ， 廣泛應用的前景。但陶瓷材料是相對較硬質的材料，加工動壓發生槽 會更加困難。 【發明内容】 有鑑於此，有必要提供一種具有相對容易成型的動壓發生槽的流 體動壓軸承。 種流體動壓軸承，包括一具有兩端開口的軸套、可旋轉地收容 於5亥軸套内的轉軸及填充於該軸套與轉軸之間以當轉轴旋轉時產生動 壓的潤滑流體，該軸套與轉轴之間於該軸套兩端開口位置各設一防漏 6 1284716 區，该軸套與轉軸之間設有多數轴向延伸的動壓發生槽，以使該動壓 建立於該兩防漏區之間的軸套中央區域。 一種流體動壓軸承，包括一軸套及一可旋轉地收容於該軸套内的 轉轴，該軸套與轉軸之間形成有間隙，該間隙中收容有潤滑流體，該 軸套内壁在圓周方向分佈有數個動壓發生槽，該軸套於每一動壓發生 槽位置的_與該轉軸之間關隙沿該轉麵旋轉方向具有一較大間 隙及-較小賊，以當轉滅轉時將位於所述較大職_潤滑流體 驅動至所述較小間隙内建立壓力。 在該流體動壓轴承中，利用轴套與轉轴之間沿轉轴的轉動方向的 間隙變化形成動壓，動壓發生槽在轴向上可以設置成可方便模具 加工的形狀與尺寸，械於習知的魚骨狀動壓發生槽，將可大量降低 加工難度’尤其適合於·軸承等具有較高硬度_心另外，兩端 設置防漏區，可有效防止潤滑流體的泄漏。 【實施方式】 請參考第-圖及第二圖，該流體動壓軸承包括—轴套⑺及一轉袖 2〇。本實施例中，該軸套10及轉軸2〇由陶究材料製成。該轴套川設 有-貫穿的軸孔12 ’從而在轴套1G _向兩端形成開口端Μ。該轉 軸2〇可轉動地收容於該軸套1〇的軸孔12中。該轴套ι〇的内独斑 該轉轴2_壁21之間形她承間隙，該間隙中收容有潤滑流㈣ (第五圖），以當鋪轴20旋轉時妹套1()與_ 2Q之間建立動麼， 防止兩者間直接接觸。 7 1284716 該軸套10的内壁11形成數個動壓發生槽16 壓發土n 摩至定蚊 輕該轴套10於靠近該二開口端14的内壁11為一稍微 偏離軸套10轴向^徽不系面>從而使該二開口端14的開戸呈錐形。 -------------- \ 广. :;.. 該軸套10外壁還形成有連接通道19，該連接通道19連適位於該輛套 10兩端的空間，可以在組裝軸承模組時起到排氣的作用，還可以作為 潤滑流體30的循環通道。 請參考第三圖，為該轴套10與轉轴20組合時的橫截面示意圖， 為清楚顯示轴套10内壁11上的動壓發生槽16,填充於該轉軸20與轴 套10之間的满滑流體30未顯示出。可以看出，該軸套1〇於每一動壓 發生槽16位置的内壁11為一弧面。該弧面與轉軸20的外壁21之間 的間隙該轉轴20的旋轉方向逐漸減小。在位於較大間隙屯的位 置，其收容有相對較多的潤滑流體30。在轉軸20旋轉產生的離心力帶 動下，位於該較大間隙山位置的潤滑流體30將被驅動至較小間隙d2 位置，產生動壓以徑向上支撐轉轴20。因為該數個動壓發生槽16是沿 軸向延伸，因此其建立的動壓亦是沿轴向分佈。 可以看出，該動壓的建立是靠軸套10與轉軸20之間的間隙d在 轉軸20旋轉方向上的變化，造成對潤滑流體30的擠壓，從而建立壓 力。因此，在動壓發生槽16沿轴套1〇徑向上的形狀與尺寸的設計可 充分考量模具的加工難易度。在本實施例中，動壓發生槽16貫穿轴套 10，因此可以很容易地使用模具加工，相對於習知技術中的魚骨狀動 8 1284716 壓發生槽，該動壓發生槽16的加工難度顯著降低。而且，該動壓發生 槽16還可以很好的配合陶瓷軸承，利用燒結技術在陶瓷軸套1〇内壁 11成型動壓發生槽16。 請參考第四圖及第五圖，為該軸套10與轉軸2〇組合時的縱截面 示意圖。該轴套10的靠近開口端14的微小斜面18與轉軸2〇外壁21 之間形成一向軸套10開口端的方向逐漸擴大的錐形間隙，該處的間隙 尺寸在20微米至300微米之間，由於該處巧間隙很小，且為向開口端 逐漸擴大的形狀，因此可利用潤滑流體30的毛細作用達到防止潤滑流 體30在開口端14洩漏的功能。靠近開口端14的微小斜面18所在的 區域主要是一個防漏區，因此在該微小斜面18所處的位置不會建立動 壓，而動壓主要建立在兩端防漏區之間的轴套1〇中央區域。 上述實知方式中，該轴套10為兩端開口，根據需要亦可形成單端 開口的結構，在該單端開口的内壁設置微小斜面以利用毛細現象達到 防漏功能。 【圖式簡單說明】 第一圖為本發明實施例的流體動壓韩承的立體組合圖。 第二圖為本發明實施例的流體動壓軸承的軸套的立體剖視圖。 第三圖為本發明實施例的流體動壓轴承的橫截面示意圖。 第四圖為本發明實施例的流體動壓轴承的縱載面示意圖。 第五圖為第四圖的圈V部分的放大圖。 【主要元件符號說明】 1284716 - 10軸套 11内壁 12軸孔 14開口端 16動壓發生槽 18微小斜面 19連接通道 20轉軸 21外壁 30潤滑流體BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid dynamic pressure bearing, and more particularly to a dynamic pressure generating groove structure of a fluid dynamic pressure bearing. [Prior Art] In recent years, fluid dynamic pressure bearings have been increasingly used in the use of small motors such as fan motors or disk drive motors. The fluid dynamic pressure bearing establishes a pressure between the shaft center and the bearing by the oil film to separate the bearing from the shaft center and prevent wear between the two. Usually, a fishbone-shaped dynamic pressure generating groove is engraved on the inner wall of the bearing or the outer wall of the shaft, and the lubricating oil is concentrated inside the dynamic pressure generating groove, and pressure is established along the dynamic pressure generating groove. The dynamic pressure generating groove for processing fish bone generally needs to insert a cutter into the bearing bore to cut or squeeze to form a groove. When the electronic product is gradually miniaturized and the inner bore of the bearing is getting smaller and smaller, it is very difficult to process the fishbone-shaped dynamic pressure generating groove in the inner bore of the bearing. Moreover, with the development of ceramic technology, ceramic materials have also been widely used in dynamic pressure bearings. However, ceramic materials are relatively hard materials, and it is more difficult to process dynamic pressure generating grooves. SUMMARY OF THE INVENTION In view of the above, it is necessary to provide a fluid dynamic pressure bearing having a dynamic pressure generating groove which is relatively easy to mold. The fluid dynamic pressure bearing comprises a bushing having two ends open, a rotating shaft rotatably received in the 5th bushing sleeve, and a lubricating fluid filled between the bushing and the rotating shaft to generate dynamic pressure when the rotating shaft rotates , a gap-proof 6 1284716 area is arranged between the sleeve and the rotating shaft at the two ends of the sleeve, and a plurality of axially extending dynamic pressure generating grooves are arranged between the sleeve and the rotating shaft to make the dynamic pressure A central region of the sleeve is established between the two leak-proof zones. A fluid dynamic pressure bearing includes a sleeve and a rotating shaft rotatably received in the sleeve, wherein a gap is formed between the sleeve and the rotating shaft, the gap contains a lubricating fluid, and the inner wall of the sleeve is in the circumferential direction a plurality of dynamic pressure generating grooves are distributed, and the gap between the _ and the rotating shaft at the position of each dynamic pressure generating groove has a larger gap along the rotating direction of the rotating surface and a smaller thief The pressure is established by driving the larger duty lubricating fluid into the smaller gap. In the fluid dynamic pressure bearing, the dynamic pressure is formed by the gap change between the sleeve and the rotating shaft in the rotating direction of the rotating shaft, and the dynamic pressure generating groove can be set in the axial direction to facilitate the shape and size of the mold processing. In the well-known fishbone dynamic pressure generating groove, the processing difficulty can be greatly reduced. It is especially suitable for bearings and has high hardness. In addition, a leak-proof area is provided at both ends, which can effectively prevent leakage of lubricating fluid. [Embodiment] Referring to Figures -1 and 2, the hydrodynamic bearing includes a sleeve (7) and a sleeve 2 〇. In this embodiment, the sleeve 10 and the shaft 2 are made of a ceramic material. The bushing is provided with a through-hole 12' to form an open end turn at both ends of the bushing 1G_. The shaft 2 is rotatably received in the shaft hole 12 of the sleeve 1〇. The inner sleeve of the sleeve ι〇 is shaped by the gap between the shaft 2_the wall 21, and the gap contains a lubricating flow (four) (fifth figure), and the sleeve 1 () and the _ when the pawn 20 rotates Establish a movement between 2Q to prevent direct contact between the two. 7 1284716 The inner wall 11 of the sleeve 10 is formed with a plurality of dynamic pressure generating grooves 16 to press the soil n to the mosquitoes. The inner wall 11 of the sleeve 10 near the two open ends 14 is slightly offset from the sleeve 10 axially ^ The emblem is not tied &> such that the opening of the two open ends 14 is tapered. -------------- \ 广. :;.. The outer wall of the sleeve 10 is also formed with a connecting passage 19, which is connected to the space at both ends of the sleeve 10, and can be When the bearing module is assembled, it functions as an exhaust gas, and can also serve as a circulation passage of the lubricating fluid 30. Referring to the third figure, a cross-sectional view of the sleeve 10 and the shaft 20 is combined. In order to clearly show the dynamic pressure generating groove 16 on the inner wall 11 of the sleeve 10, the shaft 20 is filled between the shaft 20 and the sleeve 10. The full slip fluid 30 is not shown. It can be seen that the inner wall 11 of the sleeve 1 at the position of each dynamic pressure generating groove 16 is a curved surface. The rotation direction of the rotary shaft 20 is gradually reduced by the gap between the curved surface and the outer wall 21 of the rotary shaft 20. At a location that is located at a relatively large gap, it contains a relatively large amount of lubricating fluid 30. Driven by the centrifugal force generated by the rotation of the rotating shaft 20, the lubricating fluid 30 located at the position of the larger gap mountain will be driven to the position of the smaller gap d2, generating dynamic pressure to support the rotating shaft 20 in the radial direction. Since the plurality of dynamic pressure generating grooves 16 extend in the axial direction, the dynamic pressure they establish is also distributed in the axial direction. It can be seen that the dynamic pressure is established by the change of the gap d between the sleeve 10 and the rotating shaft 20 in the direction of rotation of the rotating shaft 20, causing the pressing of the lubricating fluid 30 to establish the pressure. Therefore, the design of the shape and size of the dynamic pressure generating groove 16 in the radial direction of the sleeve 1 can fully consider the ease of processing of the mold. In the present embodiment, the dynamic pressure generating groove 16 is penetrated through the sleeve 10, so that the mold processing can be easily performed, and the groove is formed in comparison with the conventional fishbone movement 8 1284716, and the dynamic pressure generating groove 16 is processed. The difficulty is significantly reduced. Further, the dynamic pressure generating groove 16 can be well fitted to the ceramic bearing, and the dynamic pressure generating groove 16 is formed in the inner wall 11 of the ceramic bushing 1 by a sintering technique. Please refer to the fourth and fifth figures for a longitudinal section of the sleeve 10 and the shaft 2〇. The micro-bevel 18 of the sleeve 10 near the open end 14 and the outer wall 21 of the rotating shaft 2 form a tapered gap which gradually expands toward the open end of the sleeve 10, and the gap size is between 20 micrometers and 300 micrometers. Since the clever gap is small and is gradually enlarged toward the open end, the capillary action of the lubricating fluid 30 can be utilized to prevent the lubricating fluid 30 from leaking at the open end 14. The area of the micro-bevel 18 near the open end 14 is mainly a leak-proof area, so that no dynamic pressure is established at the position where the micro-bevel 18 is located, and the dynamic pressure is mainly established between the leak-proof areas at both ends. 1〇 Central area. In the above-mentioned known embodiment, the sleeve 10 is open at both ends, and a single-end opening structure can be formed as needed, and a micro-bevel is provided on the inner wall of the single-end opening to achieve a leak-proof function by capillary action. BRIEF DESCRIPTION OF THE DRAWINGS The first figure is a three-dimensional combination diagram of a fluid dynamic pressure Han Cheng according to an embodiment of the present invention. The second figure is a perspective cross-sectional view of a bushing of a fluid dynamic bearing according to an embodiment of the present invention. The third figure is a schematic cross-sectional view of a fluid dynamic bearing according to an embodiment of the present invention. The fourth figure is a schematic view of the longitudinal load surface of the fluid dynamic bearing according to the embodiment of the present invention. The fifth figure is an enlarged view of the portion V of the circle of the fourth figure. [Main component symbol description] 1284716 - 10 bushing 11 inner wall 12 shaft hole 14 open end 16 dynamic pressure generating groove 18 micro bevel 19 connecting passage 20 rotating shaft 21 outer wall 30 lubricating fluid