200912156 九、發明說明 【發明所屬之技術領域】 本發明是有關可適用於應用在各種用途的，馬胃 '電:子 機器和電源設備等之冷卻的風扇馬達之作爲軸#@軸承組 件。 【先前技術】 風扇馬達係爲載置在中央演算元件等的1C封裝上’ 且設置在個人電腦和電源設備等的本體框等，藉由旋轉翼 的旋轉導入外氣，或是排出框內的空氣來冷卻電子機器等 。此種風扇馬達係在框形之機殻的中央部固定著馬達，具 有在該旋轉軸安裝風扇的構造。第5圖係槪略表示風扇馬 達之一實施例的縱剖面圖。轉子（回轉翼）係由藉鎖固在回 轉軸3的輪轂4、和形成在輪轂4的風扇5、和固定在輪 轂4之內周側的多極著磁的磁鐵7所構成。機殼係由形成 有空氣孔61的外盒6、和在被固定於外盒6內的軸承殼體 2，從開口部側固定著軸承1之構造的軸承組件、和具備 線圏8的定子9所構成。轉子的旋轉軸3係藉由機殼的軸 承1旋轉自如的支承，驅動轉子的馬達，係藉由轉子的磁 鐵7、機殼的線圈8以及定子9所構成。在此種風扇馬達 中，藉由通電至線圈8，並因線圈8與定子9所產生的旋 轉磁場和具有多極著磁之磁鐵7的磁場的作用，讓轉子被 旋轉驅動，利用形成在轉子的風扇5，產生既定方向的氣 流’從空氣孔61進行空氣的吸入或排出。 200912156 在如上述構造的風扇馬達的軸承，是採用燒結含油軸 承（例如專利文獻υ ’燒結含油軸承是採用在青銅或鐵、 同銅系的多孔質燒結合金的氣孔內，浸漬碳化氫系的合成 油或在碳化氫系合金混合金屬皂作爲增稠劑的合成潤滑油 等的軸承。 〔專利文獻1〕日本特開平1 0-1 64794號公報 【發明內容】 〔發明欲解決之課題〕 此種風扇馬達其使用量乃隨著近年個人電腦和遊戲機 寺之因高機能化的散熱量增加而增加。其中一方面，希望 風扇馬達之長壽命化和省電化，長壽命化和減低摩擦係數 對使用在風扇馬達的軸承更爲重要。因而，本發明係提供 長壽命、摩擦係數低的軸承爲其課題。 〔用以解決課題之手段〕 爲達成上述之長壽命化和低摩擦化，本發明之軸承組 件’係爲具有：一端形成開口 ’並且另一端被閉塞的圓筒 狀殼體；和由圓筒狀的燒結體與浸漬在前述燒結體之氣孔 中的潤滑油所形成’外周被固定在前述殻體的內周面，用 以將旋轉軸旋轉自如的支承在內周的圓筒狀燒結軸承的軸 承組件’其特徵爲：在前述燒結軸承的內周面，形成三〜 九條螺旋形的內周溝槽，前述內周溝槽，係在前述內周面 之展開圖中’對軸向呈5〜15。傾斜，並且一端連接至前述 -5- 200912156 燒結軸承的一端面，另一端自前述燒結軸承的另一端面隔 絕，將前述燒結軸承的一端面配置在前述機殼被閉塞的另 一端側。 〔發明效果〕 藉由本發明的軸承組件，由於能防止潤滑油漏洩，並 能良好的維持滑動面的潤滑狀態，因此使用作爲風扇用軸 承，藉此能延長軸承部分的壽命並減低摩擦係數，有助於 風扇馬達的超壽命化和省電化。 【實施方式】 〔用以實施發明的最佳形態〕 以下，參照圖面說明本發明之軸承組件的一實施形態 。第1圖是構成本發明之軸承組件的燒結含油軸承之一實 施形態，第1圖（a)是軸承10之開放端側的端面圖，第1 圖（b)是軸承1 0之軸向剖面圖，第1圖（c)是軸承1之閉塞 端側的端面圖。第2圖是使用第1圖之軸承1 〇的軸承組 件之軸向剖面圖，第3圖是第1圖之軸承10的內周面之 展開圖。 構成本發明之軸承組件的軸承1 0係由燒結合金所製 成的燒結軸承，在其氣孔中浸漬著碳化氫系的合成油，或 在碳化氫系合成油中混合金屬皂作爲增稠劑之合成潤滑油 等的潤滑油。 —般風扇馬達用軸承係採用內徑爲1 . 5〜3 . 5 m m左右， -6- 200912156 軸向之長度爲5〜15mm左右的軸承，本發明之軸承也 形成同樣的尺寸，藉此例如可適用作爲支承第5圖所示之 風扇馬達的回轉軸3的軸承1。於以下，雖是記載有關將 本發明的軸承組件共用於第5圖之風扇馬達的形態，但本 發明的軸承組件並不限於此。 如第1圖（b)所示，在軸承10的內周面11，形成有對 軸向傾斜的螺旋狀之內周溝槽12，該內周溝槽係連接至軸 承1 〇之一方的端面（圖中下側的閉塞側端面1 3 )，自另一 方的端面（圖中上側的開口側端面1 4)被隔絕，未連接。軸 承1 〇係如第2圖所示，壓入或接著而固定在一端形成開 口並且另一端被閉塞之殼體20的內周面，藉此構成軸承 組件。此時，在殼體20之被閉塞的另一端側，配置連接 著上述軸承1 0之內周溝槽的端面（圖中下側的閉塞側端面 13)，在殼體20的開口側配置未連接上述軸承1〇之內周 溝槽的端面（圖中上側的開放側端面1 4)。 上述內周溝槽1 2是作爲儲油的功能，具有將潤滑油 供給到內周面1 1(滑動面）的作用。又，內周溝槽12係爲 如第3圖所示，在內周面11的展開圖中，在與回轉軸3 之滑動方向相反的方向，僅傾斜角度0的螺旋狀傾斜溝槽 。因而，旋轉軸3旋轉的話，旋轉軸3的滑動速度及對應 於sin Θ所增加的流動壓，會從閉塞側端面1 3向著開放側 端面1 4施加於內周溝槽1 2的潤滑油。在本發明的軸承組 件中，如上述，形成使內周溝槽12傾斜並且連接至閉塞 側端面1 3，未連接至開放側端面1 4的構造，藉此可得到 200912156 (1)加大儲油之長邊方向的長度1，提高對滑動面之潤滑作 用的作用、（2)產生潤滑油沿著內周溝槽1 2流至閉塞側端 面1 3的流動壓，提高閉塞側端面1 3附近的油壓，並提高 供給至內周面之油膜的強度之作用、以及（3 )產生潤滑油沿 著內周溝槽1 2流至閉塞側端面1 3的流壓，藉此防止潤滑 油從燒結含油軸承的開放側端面1 4漏洩，抑制因潤滑油 的消耗降低壽命的作用，爲了提高上述（1)〜（3)的效果，內 周溝槽12的寬以0.2〜1.5mm左右爲宜。但，第3圖之內 周溝槽爲了易於理解，故放大寬度而示之。 上述（1) ~ (3 )的效果’係在對軸承1 〇之內周面的展開 圖之軸向的上述內周溝槽12的傾斜角度0爲20。以下之範 圍（〇<0 S20)觀察’實用上在5〜15。的範圍很有效。傾 斜角度（9不滿5°的話，就不能充分獲得上述〜（3)的作用 。另一方面’傾斜角度0超過1 5°的話，雖然儲油之長邊 方向長度1加大’但由於潤滑油的流動壓變大，潤滑油易 從內周溝槽1 2退開到閉塞側端面i 3，因此結果會降低潤 滑油供給至內周面11的作用。因此，內周溝槽12的傾斜 角度0係對軸向爲5〜15°最適合。 如上述設定內周溝槽1 2的傾斜角度0 ，內周溝槽i 2 連接至開放側端面1 4的話，藉由因隨著軸之旋轉的發熱 的潤滑油之膨脹，易發生潤滑油從開放側端面1 4漏洩， 降低軸承的壽命。因此，內周溝槽1 2必須爲未連接到開 放側端面1 4的構造。由此觀點，在上述之一般大小的風 扇馬達用軸承中，開放側之內周溝槽端部1 5與軸承的端 -8 - 200912156 面14之距離d設定在〇.5mm以上爲宜。但內周溝槽端部 1 5與開放側端面1 4之距離d過大的話，由於軸承之內周 面1 1之往上述（1)的滑動面之潤滑作用下降，因此距離d 以不超過2mm的範圍爲宜。 內周溝槽1 2之條數太少的話，由於缺乏上述之作用 ，因此爲了使該作用普及到軸承之內周面11的整體，因 此必須形成三條以上。另一方面，內周溝槽1 2之條數太 多的話，因爲滑動面的面積減少，承受滑動面的面壓增加 ，所以上限爲九條。又，垂直於內周溝槽12之長軸方向 的斷面形狀並未特別限定，在第2、4圖中，雖然是形成 溝底的寬小於溝槽之開口寬的梯形，但也可爲寬度一定之 斷面爲長方形的溝槽，或斷面爲三角形、半圓形或半橢圓 形等之溝底狹窄的溝槽。 在具有如上述之構造的軸承組件中，提高內周面1 1 ( 滑動面）之素材密度的話’由內周溝槽1 2所供給的潤滑油 變得難以通過燒結含油軸承的氣孔而漏出，潤滑油的壓力 昇高，潤滑油的油膜變堅固。其另一方面，內周溝槽1 2 之溝壁面的素材密度也提高的話，原本具有燒結含油軸承 的潤滑油之循環作用會減損。由該些觀點來看，內周面1 1 的氣孔率形成在5〜2 8% ’內周溝槽1 2的溝壁面的氣孔率 形成在3 0〜4 5 %爲宜。爲了形成此種氣孔率的構造，準備 具備氣孔率形成在3 0〜4 5 %之內周溝溝的燒結含油軸承用 的燒結體素材，在進行分級（sizing )等的再壓縮之際， 使用圓筒狀的核心柱（core rod )，使內周面塑性變形， -9 - 200912156 消除氣孔，將開口在內周面的氣孔率調整至5〜28%，藉此 得到所要的軸承。 在本發明的軸承組件中，如第4圖所示，更在內周溝 槽12連通的側端面13，向著旋轉軸3的旋轉方向，從外 徑側螺旋捲繞至內徑側，形成終端部與前述內周溝槽1 2 連通的端面溝槽1 6爲宜的形態。如上述，在軸承1 〇的閉 塞側端面1 3上形成端面溝槽1 6的話，儲存在不隨著旋轉 軸3的旋轉，藉由殼體2 〇與軸承丨〇的閉塞側端面13所 形成的空間的潤滑油，會沿著端面溝槽1 6被引入到旋轉 軸3的方向，將引入的潤滑油供給到內周溝槽1 2，就能提 高對上述（2)之潤滑油的內周面1 1的供給作用。雖然該端 面溝槽16可形成正好與內周溝槽12相同的數量，但也可 少於內周溝槽1 2。以端面溝槽1 6的斷面爲由外徑側向著 內徑側減少的方式形成端面溝槽1 6的話，引入潤滑油的 效率就很優良。 如上述’因爲本發明的軸承組件，係藉由具有特定形 態之內徑溝槽的燒結含油軸承與殼體的組合而簡潔的構成 ’所以即可放大軸承的尺又不會讓構造複雜化，能改善潤 滑油的保持性，提高耐久性。因而’例如使用本發明的軸 承組件作爲第5圖之風扇馬達的軸承1及殼體2，藉此提 昇風扇馬達的耐久性，並且可應用於以其他的馬達或各種 旋轉構件爲構成要素的機器裝置的軸承，有助於機器、裝 置的小型化、長壽命化。 -10- 200912156 〔實施例〕 將在鐵粉末中添加45質量％的電解銅粉末、5質量％ 的箔狀銅粉末、3質量％的錫粉末的比例所混合的原料粉 末，塡充到模具加以壓縮成型，得到外徑3 .5 mm '內徑 2.5mm、高度i〇mm之略圓筒形狀的軸承用的成型體（試 料1〜6 )。再者，如表1所示，對每個試料，改變傾斜角 度0，形成六條內周溝槽1 2。 內周溝槽12，係形成斷面爲寬0.5mm的長方形，且 連接至一方的端面13，未連接至另一方的端面〗4，內周 溝槽1 2的端部1 5與內周溝槽未連接的開放側端面1 4之 距離爲1 mm。又，爲了比較，亦準備內周溝槽12連接到 兩端面13、14的軸承（試料7)。再者，該些之成型體的密 度比係分別將模製壓力調整成70%。將該些成型體在氨分 解氣體環境中以7 8 0 °C進行燒結後，再壓縮內周面1 1，使 內周面1 1的氣孔率成爲1 〇 %。再者，內周溝槽1 2的溝壁 面之氣孔率爲3 8 %。 在已得到的試料，浸漬以具有相當I S Ο V G 6 8之粘度 的聚α -烯烴爲主成份的合成潤滑油（商品名F L ΟIL 9 7 2 P -68 ’關東化成工業（股）製），製作軸承（試料1〜7)。 已得到的軸承（試料1〜7)，係如第2圖所示，以連通 內周溝槽12之閉塞側端面13與殼體2〇之底部面對面的 方式壓入固定在一端爲開口的不銹鋼製的殻體2〇，製作試 料1〜7的軸承組件。在上述的軸承組件試料，插入由外徑 2.5mm相當HS SGC材料所製成的旋轉軸3，在環境溫度 -11 - 200912156 8〇°C，使旋轉軸3以轉數：5 000rpm旋轉，測定摩擦係數 ，並且旋轉軸3完成運轉200小時後，測定軸承組件試料 的重量，並測定自軸承端面起的潤滑油的耗油率。該些結 果一倂標示於表1。再者，表1的內周溝槽之傾斜角度0 ，係爲對內周面1 1的展開圖的軸向之傾斜角度，0 =0°的 試料，係形成內周溝槽1 2平行軸向，內周溝槽並未傾斜 之情形的範例。又，試料7，係內周溝槽1 2亦連接在兩端 面1 3、1 4的任一面。 表1 傾斜角度 (υ 摩擦 係數 耗油率 (% ) 備考 試料 1 0 0.16 17.0 試料 2 2 0.15 15.5 試料 3 5 0.11 8.0 試料 4 10 0.10 6.5 試料 5 15 0.1 2 8.5 試料 6 20 0.15 16.0 試料 7 1 0 0.16 27.5 內周溝溝連通至兩端 由表1確認，相較於內周溝槽的傾斜角度不滿5 °的試 料1及2、傾斜角度超過1 5 °的試料6，傾斜角度爲5〜1 5 ° 的試料3〜5，係摩擦係數低，且在此範圍呈現良好的滑動 特性。又，試料7與試料3〜5相比，潤滑油的漏出量增多 ，摩擦係數也出現較大的値。由此情形了解到內周溝槽1 2 未連接到殻體2 0之開口側的端面1 4的構造是很重要的。 -12- 200912156 〔產業上的可利用性〕 本發明之軸承組件，最適合應用於風扇馬達等之旋轉 驅動機構’作爲風扇馬達的軸承使用，藉此可提昇馬達的 耐久性，有助於可靠性的提昇。 【圖式簡單說明】 第1圖是有關本發明之風扇馬達用燒結含油軸承之一 實施形態的模式圖’（a)是軸承之開放端側端面的俯視圖， (b)係軸承之軸向剖面圖，（c)是軸承之閉塞端側端面的仰 視圖。 第2圖是有關本發明之軸承組件之一實施形態的軸向 剖面圖。 第3圖是有關本發明之風扇馬達用軸承之一實施形態 的第圖所示軸承之內周面的展開圖。 第4圖是有關本發明之風扇馬達用軸承之其他實施形 態，在連接內周溝槽之側的端面形成端面溝槽之軸承的俯 視圖。 第5圖是風扇馬達之一例的縱剖面圖。 【主要元件符號說明】 1、1 〇 :軸承 11 :軸承內周面 12:內周溝槽 13 :閉塞側端面 -13- 200912156 1 4 :開放側端面 1 5 :內周溝槽端部 1 6 :端面溝槽 2、2 0 :軸承殼體 3 :旋轉軸 4 :輪轂（h u b ) 5 ‘旋轉翼（風扇） 6 :外盒 6 1 :空氣孔 7 :磁鐵 8 :線圈 9 :定子（stator)。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 [Prior Art] The fan motor is mounted on a 1C package such as a central calculation element, and is provided in a main body frame such as a personal computer or a power supply device, and is introduced into the outside air by the rotation of the rotary wing or discharged into the frame. Air to cool electronic machines, etc. Such a fan motor has a motor fixed to a central portion of a frame-shaped casing, and has a structure in which a fan is attached to the rotating shaft. Fig. 5 is a longitudinal sectional view showing an embodiment of a fan motor. The rotor (rotary wing) is composed of a hub 4 fixed to the revolving shaft 3 by a lock, a fan 5 formed on the hub 4, and a multi-pole magnet 7 fixed to the inner peripheral side of the hub 4. The casing is an outer casing 6 formed with an air hole 61, and a bearing housing 2 fixed to the outer casing 6, a bearing assembly having a structure in which the bearing 1 is fixed from the opening side, and a stator having the wire 8 9 constitutes. The rotating shaft 3 of the rotor is rotatably supported by the bearing 1 of the casing, and the motor for driving the rotor is constituted by the magnet 7 of the rotor, the coil 8 of the casing, and the stator 9. In such a fan motor, by energizing the coil 8, and by the action of the rotating magnetic field generated by the coil 8 and the stator 9 and the magnetic field of the magnet 7 having the multipole magnetism, the rotor is rotationally driven and formed in the rotor. The fan 5 generates a flow of air in a predetermined direction 'intake or discharge of air from the air hole 61. 200912156 In the bearing of the fan motor constructed as described above, a sintered oil-impregnated bearing is used (for example, the patent document υ 'Sintered oil-impregnated bearing is a composite of carbon nanotubes impregnated in the pores of a bronze or iron, copper-based porous sintered alloy. A bearing of a synthetic lubricating oil or the like which is a thickener in a hydrocarbon or a hydrocarbon-based alloy. [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei No. 0-1 64794 The use of the fan motor has increased with the increase in the amount of heat dissipated by the personal computer and the game machine in recent years. On the one hand, it is desirable to extend the life and power of the fan motor, to extend the life and reduce the friction coefficient. The bearing used in the fan motor is more important. Therefore, the present invention provides a bearing having a long life and a low friction coefficient. [Means for Solving the Problem] In order to achieve the above-described long life and low friction, the present invention The bearing assembly 'has a cylindrical housing having an opening formed at one end and being occluded at the other end; and a sintered body of a cylindrical shape The lubricating oil immersed in the pores of the sintered body is formed with a 'outer circumference fixed to the inner peripheral surface of the casing, and the bearing assembly of the cylindrical sintered bearing that rotatably supports the rotating shaft on the inner circumference' In the inner circumferential surface of the sintered bearing, three to nine spiral inner circumferential grooves are formed, and the inner circumferential grooves are in the developed view of the inner circumferential surface, which is 5 to 15 in the axial direction. And one end is connected to one end surface of the above-mentioned -5 - 200912156 sintered bearing, and the other end is isolated from the other end surface of the sintered bearing, and one end surface of the sintered bearing is disposed on the other end side of the casing to be closed. According to the bearing assembly of the present invention, since the lubricating oil can be prevented from leaking and the lubricating state of the sliding surface can be maintained satisfactorily, the bearing for the fan can be used, whereby the life of the bearing portion can be prolonged and the friction coefficient can be reduced, contributing to the fan. [Embodiment] [Best Mode for Carrying Out the Invention] Hereinafter, a description of the bearing assembly of the present invention will be described with reference to the drawings. Fig. 1 is an embodiment of a sintered oil-impregnated bearing constituting a bearing assembly of the present invention, wherein Fig. 1(a) is an end view of the open end side of the bearing 10, and Fig. 1(b) is an axis of the bearing 10; In the cross-sectional view, Fig. 1(c) is an end view of the bearing end side of the bearing 1. Fig. 2 is an axial sectional view of the bearing assembly using the bearing 1 of Fig. 1, and Fig. 3 is a first figure. Development view of the inner peripheral surface of the bearing 10. The bearing 10 constituting the bearing assembly of the present invention is a sintered bearing made of a sintered alloy, and is immersed in a hydrocarbon-based synthetic oil in the pores thereof or synthesized in a hydrocarbon-based system. A lubricating oil such as a synthetic lubricating oil in which oil is mixed with a metal soap as a thickener. The bearing of the general fan motor has an inner diameter of 1. 5 to 3. 5 mm or so, -6-200912156, the length of the axial direction is 5~ The bearing of the present invention is also formed in the same size as the bearing of about 15 mm, whereby the bearing 1 as the rotary shaft 3 supporting the fan motor shown in Fig. 5 can be applied, for example. In the following, the bearing assembly of the present invention is collectively used in the fan motor of Fig. 5, but the bearing assembly of the present invention is not limited thereto. As shown in Fig. 1(b), a spiral inner circumferential groove 12 which is inclined to the axial direction is formed on the inner circumferential surface 11 of the bearing 10, and the inner circumferential groove is connected to one end face of the bearing 1 (The lower end side end surface 1 3 in the figure) is isolated from the other end surface (the upper side opening side end surface 14 in the drawing), and is not connected. The bearing 1 is attached to the inner peripheral surface of the casing 20 which is formed at the one end and which is closed at the other end, as shown in Fig. 2, thereby constituting the bearing assembly. At this time, the end surface of the inner circumferential groove of the bearing 10 (the lower closing side end surface 13 in the drawing) is disposed on the other end side of the casing 20 that is closed, and the opening side of the casing 20 is disposed. An end surface of the inner circumferential groove of the above bearing 1 (the upper open end surface 14 of the drawing) is connected. The inner circumferential groove 12 functions as an oil reservoir and has a function of supplying lubricating oil to the inner circumferential surface 11 (sliding surface). Further, as shown in Fig. 3, the inner circumferential groove 12 is a spiral inclined groove having an angle of only 0 in a direction opposite to the sliding direction of the rotary shaft 3 in the developed view of the inner circumferential surface 11. Therefore, when the rotary shaft 3 rotates, the sliding speed of the rotary shaft 3 and the flow pressure corresponding to the increase of sin , are applied to the lubricating oil of the inner circumferential groove 12 from the closing side end surface 1 3 toward the open side end surface 14 . In the bearing assembly of the present invention, as described above, a configuration is formed in which the inner circumferential groove 12 is inclined and connected to the closing side end surface 13 and not connected to the open side end surface 14, thereby obtaining an increase in the 200912156 (1) The length 1 of the longitudinal direction of the oil increases the effect of the lubricating action on the sliding surface, and (2) the flow pressure of the lubricating oil flowing along the inner circumferential groove 12 to the end surface 13 of the closing side, and the end surface 13 of the closing side is raised. The oil pressure in the vicinity increases the strength of the oil film supplied to the inner circumferential surface, and (3) the flow pressure of the lubricating oil flowing along the inner circumferential groove 12 to the end surface 13 of the closing side, thereby preventing the lubricating oil Leakage from the open end surface 14 of the sintered oil-impregnated bearing suppresses the action of reducing the life due to the consumption of the lubricating oil. In order to improve the effects (1) to (3), the width of the inner circumferential groove 12 is about 0.2 to 1.5 mm. should. However, the inner groove of Fig. 3 is shown in an enlarged width for easy understanding. The effect of the above (1) to (3) is such that the inclination angle 0 of the inner circumferential groove 12 in the axial direction of the development view of the inner circumferential surface of the bearing 1 is 20 . The following range (〇 <0 S20) observations is practically 5 to 15. The scope is very effective. When the inclination angle (9 is less than 5°, the effect of the above-mentioned ~(3) cannot be sufficiently obtained. On the other hand, if the inclination angle 0 exceeds 15°, the length 1 of the longitudinal direction of the oil storage is increased 'but due to the lubricating oil The flow pressure becomes large, and the lubricating oil is easily retracted from the inner circumferential groove 12 to the closing side end surface i3, so that the effect of the lubricating oil supply to the inner circumferential surface 11 is lowered as a result. Therefore, the inclination angle of the inner circumferential groove 12 The 0-axis is preferably 5 to 15° in the axial direction. As described above, the inclination angle 0 of the inner circumferential groove 12 is set, and the inner circumferential groove i 2 is connected to the open-side end surface 14 as it is rotated by the shaft. The expansion of the heat-generating lubricating oil is liable to cause leakage of the lubricating oil from the open-side end face 14 to lower the life of the bearing. Therefore, the inner circumferential groove 12 must be a structure that is not connected to the open-side end face 14 . In the above-described fan motor bearing of a general size, the distance d between the inner circumferential groove end portion 15 of the open side and the end -8 - 200912156 surface 14 of the bearing is preferably set to 〇.5 mm or more. If the distance d between the end portion 15 and the open side end face 14 is too large, due to the inner circumference of the bearing In the case where the lubricating effect of the sliding surface of the above (1) is lowered, the distance d is preferably not more than 2 mm. If the number of the inner circumferential grooves 1 2 is too small, the above-mentioned effect is lacking, so This action is spread over the entire inner peripheral surface 11 of the bearing, so it is necessary to form three or more. On the other hand, if the number of the inner circumferential grooves 1 2 is too large, since the area of the sliding surface is reduced, the surface pressure of the sliding surface is increased. Therefore, the upper limit is nine. Further, the cross-sectional shape perpendicular to the long-axis direction of the inner circumferential groove 12 is not particularly limited, and in the second and fourth figures, the width of the groove bottom is smaller than the opening width of the groove. The trapezoidal shape, but may also be a groove having a rectangular shape with a constant width, or a groove having a narrow bottom at the bottom of the triangle, a semicircle or a semi-elliptical shape. In the bearing assembly having the above configuration When the material density of the inner peripheral surface 1 1 (sliding surface) is increased, the lubricating oil supplied from the inner circumferential groove 12 becomes difficult to leak through the pores of the oil-impregnated bearing, and the pressure of the lubricating oil rises. The oil film becomes firm. On the other hand When the material density of the groove wall surface of the inner circumferential groove 1 2 is also increased, the circulation action of the lubricating oil originally having the sintered oil-impregnated bearing is degraded. From these viewpoints, the porosity of the inner peripheral surface 1 1 is formed at 5 to 2 8% The porosity of the groove wall surface of the inner circumferential groove 1 2 is preferably 30 to 4 5 %. In order to form such a porosity, it is prepared to have a porosity of 30 to 4 5 %. In the sintered body material for the sintered oil-impregnated bearing of the groove, when the sizing or the like is recompressed, a cylindrical core rod is used to plastically deform the inner peripheral surface, and -9 - 200912156 eliminates the pores. The porosity of the inner peripheral surface of the opening is adjusted to 5 to 28%, thereby obtaining the desired bearing. In the bearing assembly of the present invention, as shown in Fig. 4, the side end surface 13 that communicates with the inner circumferential groove 12 is spirally wound from the outer diameter side to the inner diameter side in the direction of rotation of the rotary shaft 3 to form a terminal. The end surface groove 16 in communication with the inner circumferential groove 12 is preferably in a form. As described above, when the end surface groove 16 is formed on the closing side end surface 13 of the bearing 1 ,, it is stored without being rotated by the rotating shaft 3, and is formed by the closing side end face 13 of the casing 2 and the bearing bore. The lubricating oil of the space is introduced into the direction of the rotating shaft 3 along the end groove 16, and the introduced lubricating oil is supplied to the inner circumferential groove 12, thereby improving the inside of the lubricating oil of the above (2). The supply of the surface 1 1 . Although the end face grooves 16 may be formed in the same number as the inner peripheral grooves 12, they may be smaller than the inner peripheral grooves 12. When the end surface groove 16 is formed such that the cross section of the end surface groove 16 is reduced from the outer diameter side toward the inner diameter side, the efficiency of introducing the lubricating oil is excellent. As described above, "because the bearing assembly of the present invention is simply constructed by a combination of a sintered oil-impregnated bearing having a specific shape of the inner diameter groove and the casing", the size of the bearing can be enlarged without complicating the structure. It can improve the retention of lubricating oil and improve durability. Thus, for example, the bearing assembly of the present invention is used as the bearing 1 and the casing 2 of the fan motor of Fig. 5, whereby the durability of the fan motor is improved, and it can be applied to a machine having other motors or various rotating members as constituent elements. The bearing of the device contributes to downsizing and long life of the machine and the device. -10-200912156 [Examples] A raw material powder in which 45 parts by mass of electrolytic copper powder, 5% by mass of foil-like copper powder, and 3% by mass of tin powder are mixed in an iron powder is placed in a mold. Compression molding was carried out to obtain a molded body for a bearing having a substantially cylindrical shape of an outer diameter of 3.5 mm and an inner diameter of 2.5 mm and a height of i 〇 mm (samples 1 to 6). Further, as shown in Table 1, for each sample, the inclination angle 0 was changed to form six inner circumferential grooves 12. The inner circumferential groove 12 is formed in a rectangular shape having a cross section of 0.5 mm in width, and is connected to one end surface 13 and is not connected to the other end surface 4, and the end portion 1 5 and the inner circumferential groove of the inner circumferential groove 12 The distance between the open side end faces 14 of the slots that are not connected is 1 mm. Further, for comparison, the inner circumferential groove 12 is also connected to the bearings of the both end faces 13, 14 (sample 7). Further, the density ratio of the molded bodies was adjusted to 70% by the molding pressure. These molded bodies were sintered at 700 ° C in an ammonia decomposing gas atmosphere, and then the inner peripheral surface 11 was compressed to have a porosity of the inner peripheral surface 11 of 1 〇 %. Further, the groove wall surface of the inner circumferential groove 12 has a porosity of 38%. In the obtained sample, a synthetic lubricating oil (trade name FL ΟIL 9 7 2 P -68 'Kuandong Chemical Industry Co., Ltd.) containing a poly-α-olefin having a viscosity equivalent to IS Ο VG 6 8 was impregnated, Bearings were prepared (samples 1 to 7). The obtained bearings (samples 1 to 7) are press-fitted to the stainless steel having an opening at one end so as to face the bottom surface of the casing 2 连通 so as to face the bottom surface of the casing 2 如 so as to be connected to the bottom surface of the inner circumferential groove 12 as shown in Fig. 2 . The casing 2 was manufactured to prepare the bearing assemblies of the samples 1 to 7. In the above bearing assembly sample, a rotating shaft 3 made of an equivalent HS SGC material having an outer diameter of 2.5 mm was inserted, and the rotating shaft 3 was rotated at a number of revolutions: 5 000 rpm at an ambient temperature of -11 - 200912156 8 〇 ° C. After the friction coefficient was completed and the rotating shaft 3 was operated for 200 hours, the weight of the bearing assembly sample was measured, and the fuel consumption rate of the lubricating oil from the bearing end face was measured. These results are shown in Table 1. Further, the inclination angle 0 of the inner circumferential groove of Table 1 is the inclination angle of the axial direction of the developed view of the inner circumferential surface 1 1 , and the sample of 0 =0° forms the parallel groove of the inner circumferential groove 1 2 An example of a case where the inner circumferential groove is not inclined. Further, in the sample 7, the inner circumferential groove 12 is also connected to either one of the both end faces 13 and 14. Table 1 Tilt angle (υ Friction coefficient fuel consumption rate (%) Preparatory test material 1 0 0.16 17.0 Sample 2 2 0.15 15.5 Sample 3 5 0.11 8.0 Sample 4 10 0.10 6.5 Sample 5 15 0.1 2 8.5 Sample 6 20 0.15 16.0 Sample 7 1 0 0.16 27.5 The inner circumferential groove is connected to both ends. It is confirmed by Table 1. The sample 1 and 2 with an inclination angle less than 5 ° of the inner circumferential groove are different from the sample 6 with an inclination angle exceeding 15 °, and the inclination angle is 5 to 1. The 5 ° sample 3 to 5 has a low coefficient of friction and exhibits good sliding characteristics in this range. Moreover, compared with the sample 3 to 5, the sample 7 has a larger amount of leakage of lubricating oil and a larger friction coefficient. From this, it is important to understand that the configuration in which the inner peripheral groove 12 is not connected to the end face 14 of the opening side of the casing 20 is important. -12- 200912156 [Industrial Applicability] The bearing assembly of the present invention It is most suitable for use as a bearing for a fan motor such as a rotary motor of a fan motor, thereby improving the durability of the motor and contributing to the improvement of reliability. [Fig. 1] Fig. 1 is related to the present invention Sintering of fan motor A schematic view of one embodiment of the oil bearing is a plan view of the open end side end face of the bearing, (b) an axial sectional view of the bearing, and (c) a bottom view of the end face of the closed end of the bearing. Fig. 3 is an axial cross-sectional view showing an embodiment of a bearing assembly according to the present invention. Fig. 3 is a development view of an inner circumferential surface of the bearing shown in Fig. 1 showing an embodiment of a bearing for a fan motor according to the present invention. Fig. 5 is a plan view showing a bearing in which an end surface groove is formed on an end surface on the side of the inner circumferential groove. Fig. 5 is a longitudinal sectional view showing an example of a fan motor. DESCRIPTION OF SYMBOLS 1、1 〇: Bearing 11: Inner peripheral surface of bearing 12: Inner circumferential groove 13: Closed side end face-13- 200912156 1 4 : Open side end face 1 5 : Inner circumferential groove end 1 6 : End groove Slot 2, 2 0 : bearing housing 3 : rotating shaft 4 : hub (hub) 5 'rotating wing (fan) 6 : outer casing 6 1 : air hole 7 : magnet 8 : coil 9 : stator