479110 經濟部智慧財產局員工消費合作社印製 A7 -—一 ___B7___ 一五、發明説明（i ) 發明背景 發明領域 · 本發明有關增壓分子泵，如適用於半導體製造設備之 真空裝置。 相關技術說明 增壓分子泵之設計中，交互安排轉子葉輪聯接至高速 轉動之轉子軸桿及以外殼固定之靜子葉輪，故於轉子軸線 之軸向上多階安排一對轉子葉輪及靜子葉輪。轉子葉輪包 含多數葉片’各傾斜一定角度。靜子葉輪包含多數葉片類 似於轉子葉輪，且各葉片之傾斜方向與轉子葉輪中葉片之 傾斜方向相反。 轉子葉輪與靜子葉輪間軸距係決定於設計因素。如轉 子葉輪與靠近入口之靜子葉輪間軸距爲5 mm左右。 如此增壓分子泵結構中，以轉子軸桿轉動轉子葉輪， 氣體分子受打擊於轉向，故轉子葉輪之葉片軸向移動，乃 排出氣體。 此類增壓分子泵係應用於半導體製造設備真空室之排 氣。進行半導體加工於真空室時，必須經常供應氣體至真 空室，並以增壓分子泵排出所供氣體。 近來趨勢係增加供應至真空室之氣體量，故正常操作 時以增壓分子泵排出之氣體量亦增加。 曾進行一項流量特性測試，決定若增加所排出之氣體 量時，習知增壓分子泵是否提供足夠真空性（排氣性能） 本紙张尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） (請先閱讀背面之注意事項再填寫本頁) •裝· 訂 線 -4- 479110 A7 B7 五、發明説明（2 ) 。測試結果顯示於圖4單點鏈線。 此處排出之氣體爲N2，以乾泵1300 (升/分）爲 輔助泵。 由結果發現，若排出氣體量小時真空性良好（如壓力 不大於1 0 — 2托耳，即得到1 0毫托耳），但排出氣體量 大時，真空性不良（如壓力大於1 0毫托耳）。 因此，本發明人欲找出排量大時無法取得良好真空性 之原因，並最初發現排氣性能降低源於轉子葉輪與靠近增 壓分子泵入口附近之靜子葉輪間軸向空間未以排出氣體形 成分子流。換言之，本發明人最初發現提高氣體流量引起 之真空性密切有關於轉子葉輪與靜子葉輪間軸距。 發明槪述 本發明根據以上觀點，其目的提供增壓分子泵，分確 保充分真空性，並提高氣體流量，即使於正常操作時提高 排放氣體之流量。 爲達上述目的，本發明增壓分子泵特徵在於： 一轉子軸桿； 一軸承，轉動支承轉子軸桿； 一馬達，轉動由軸承支承之轉子軸桿；. 對轉子軸桿提供多階轉子葉輪；及 多階轉子葉輪間分別提供多階靜子葉輪，及 轉子葉輪至少之一與對應之靜子葉輪間軸距設定値係 根據正常操作時壓力不少於1 0毫托耳條件下可處理之氣 本紙張尺度適用中國國家梯準（CNS ) Α4規格（210Χ297公釐） (請先閱讀背面之注意事項再填寫本頁) 裝·479110 Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 --- ___B7___ 15. Explanation of the Invention (i) Background of the Invention Field of the Invention The present invention relates to a booster molecular pump, such as a vacuum device suitable for semiconductor manufacturing equipment. Relevant technical description In the design of the booster molecular pump, the rotor impeller is connected to the rotor shaft rotating at high speed and the stator impeller fixed by the casing, so a pair of rotor impellers and stator impellers are arranged in multiple steps in the axial direction of the rotor axis. The rotor impeller contains a plurality of blades' each inclined at a certain angle. The stator impeller includes most blades similar to the rotor impeller, and the inclination direction of each blade is opposite to that of the rotor impeller. The wheelbase between the rotor impeller and the stator impeller is determined by design factors. For example, the wheelbase between the rotor impeller and the stator impeller near the entrance is about 5 mm. In such a turbocharged molecular pump structure, the rotor impeller is rotated by the rotor shaft, and the gas molecules are struck by the steering. Therefore, the blades of the rotor impeller move axially to exhaust the gas. This type of booster molecular pump is used for exhausting the vacuum chamber of semiconductor manufacturing equipment. When semiconductor processing is performed in a vacuum chamber, gas must always be supplied to the vacuum chamber, and the supplied gas must be discharged by a pressurized molecular pump. The recent trend is to increase the amount of gas supplied to the vacuum chamber, so the amount of gas discharged by the booster molecular pump also increases during normal operation. A flow characteristic test was conducted to determine whether the booster molecular pump can provide sufficient vacuum (exhaust performance) if the amount of exhaust gas is increased. The paper size is in accordance with China National Standard (CNS) A4 (210X 297 mm). (Please read the precautions on the back before filling out this page) • Binding and Binding -4- 479110 A7 B7 5. Description of the invention (2). The test results are shown in the single-dot chain line in Figure 4. The gas discharged here is N2, with a dry pump of 1300 (l / min) as an auxiliary pump. It is found from the results that if the amount of exhaust gas is small, the vacuum is good (for example, if the pressure is not greater than 10-2 Torr, 10 millitorr is obtained), but when the amount of exhaust gas is large, the vacuum is poor (for example, the pressure is greater than 10 millitor). Thor). Therefore, the inventors wanted to find out the reason why good vacuum cannot be obtained when the displacement is large, and initially found that the decrease in exhaust performance was due to the lack of exhaust gas in the axial space between the rotor impeller and the stator impeller near the inlet of the booster molecular pump Formation of molecular flow. In other words, the inventors initially discovered that the vacuum caused by increasing the gas flow rate is closely related to the wheelbase between the rotor impeller and the stator impeller. SUMMARY OF THE INVENTION The present invention is based on the above viewpoints, and its object is to provide a pressurized molecular pump, which can ensure sufficient vacuum and increase the gas flow rate, even during normal operation, to increase the flow rate of exhaust gas. In order to achieve the above object, the booster molecular pump of the present invention is characterized by: a rotor shaft; a bearing rotatably supporting the rotor shaft; a motor rotating the rotor shaft supported by the bearing; providing a multi-stage rotor impeller to the rotor shaft ; And multi-stage rotor impellers are provided between the multi-stage rotor impellers, and at least one of the rotor impellers and the corresponding shaft distance between the stator sub-impellers is set according to the gas that can be processed under normal operating pressure of not less than 10 millitorr This paper size is applicable to China National Standard (CNS) Α4 specification (210 × 297 mm) (Please read the precautions on the back before filling this page)
、1T 經濟部智慧財產局員工消費合作社印製 -5- 經濟部智慧財產局員工消費合作社印製 479110 A7 B7____ 五、發明説明（3) 體子流。 本發明亦可表示如下： · 即本發明增壓分子泵之特徵在於： 一轉子軸桿； 一軸承，轉動支承轉子軸桿； 一馬達，轉動由軸承支承之轉子軸桿； 對轉子軸桿提供多階轉子葉輪；及 多階轉子葉輪間分別安排多階靜子葉輪；及 轉子葉輪之一與對應靜子葉輪間至少一軸距設定値係 根據正常操作時排放量不小於1 0 0 0 s c c m條件下可 處理之氣體分子流。 轉子葉輪之一最靠近多階轉子葉輪中一入口，對應之 靜子葉輪則最靠近多階靜子葉輪中入口。 轉子葉輪之一與對應靜子葉輪之至少一軸距設定係根 據分子氣體之平均自由路徑。 如上述，根據本發明，靜子葉輪與轉子葉輪間軸距設 定値可於正常操作時入口壓力等於或大於1 〇毫托耳之條 件下處理氣體爲分子流。 因此，根據本發明，可於正常操作時壓力等於或大於 1〇毫托耳之條件下處理氣體分子流，得到充分排氣性能 。即使相較習知於正常操作時提高供至真空室之氣體量， 本發明可確保所需壓力（所需真空性），保持更大氣體流 本紙张尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） I------·I 装------訂 ^ (請先閲讀背面之注意事項再填寫本頁) 479110 A7 B7 i、發明説明（4 ) 圖式簡單說明 圖中： . (請先閲讀背面之注意事項再填寫本頁) 圖1爲增壓分子泵主要部分，說明本發明基本原理； 圖2爲轉子葉輪與靜子葉輪展開圖，顯示主要部分； 圖3爲本發明一例增壓分子泵截面圖；及 圖4顯示本發明例與習知設備進行流量特性測試結果 主要元件對照表 141 轉子葉輪 142 轉子葉輪 14 3 轉子葉輪 1 4 4 轉子葉輪 18 1 靜子葉輪 182 靜子葉輪 183 靜子葉輪 184 靜子葉輪 經濟部智慧財產局員工消費合作社印t 10 分子泵 12 轉子軸桿 14 轉子葉輪區段 16 外殼 1 8 靜子葉輪區段 2 0 軸承 2 1 馬達 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 479110 A7 B7___ 五、發明説明（5) 1 -4 a 本體 141a 葉片 · (請先閲讀背面之注意事項再填寫本頁) 2 2 電磁鐵 2 4 電磁鐵 3 0 位置感應器 32 位置感應器 3 4 位置感應器 2 6 電磁鐵 3 8 入口 3 9 出口 較佳實施例詳細說明 以下說明本發明實施例之前先說明本發明基本原理。 圖1爲本發明主要部分截面圖，省略其他部分以利說 明本發明基本原理。圖2展開圖顯示轉子葉輪1 4 1與靜 子葉輪1 8 1間關係。 經濟部智慧財產局員工消費合作社印製 本發明根據上述觀點，如圖1所示，轉子葉輪1 4 1 與至少最靠近入口之靜子葉輪1 8 1間軸距a設定値可於 正常操作時入口壓力不小於1 0毫托耳之條件下處理氣體 分子流。 若增壓分子泵用於排出正常操作時供至真空室之氣體 ，排出氣體之流量爲預定。因此，增壓分子泵必須滿足條 件，即正常操作時預定排氣量，且須同時提供真空性（如 壓力不大於2 0毫托耳）。因此’本發明可表示如下：轉 -8 - 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 479110 A7 __ B7______ 五、發明説明（6) (請先閲讀背面之注意事項再填寫本頁) 子葉輪1 4 1與至少最靠近入口之靜子葉輪1 8 1間軸距-a設定値可於正常操作時排氣量不小於1 〇 〇 〇 · S C C Μ 條件下處理氣體分子流。 接著說明根據上述原理設定轉子葉輪1 4 1與靜子某 輪1 8 1間軸距a之方法。 如上述，氣體是否可於轉子葉輪1 4 1與靜子葉輪 1 8 1間軸距處理爲分子流，係取決於氣體分子之平均自 由路徑。平均自由路徑λ均表示爲以下公式（1): λ =〇· 0 5/壓力（mm) ...... ( 1 ) 公式（1)中壓力單位爲托耳。 若平均自由路徑λ不小於上述間距a ，則氣^ _司* _王里 爲分子流。 接著說明正常操作時壓力不大於2 〇毫$胃日 理爲分子流。 根據公式（1) ’壓力爲20毫托耳之條 經濟部智慧財產局員工消费合作社印奴 由路徑λ爲2.5mm(人=2·5mm)。 因此，若轉子葉輪1 4 1與靜子葉輪丨s ^ ^ _ σ 1間軸距a 定爲不大於2 . 5mm，則壓力不大於2 $忙耳條件下 氣體可處理爲分子流。 此外，可類似設定轉子葉輪1 4 2與靜子葉輪^ 8 2 間軸距，轉子葉輪1 4 3與靜子葉輪1 8 3間_ ^ _ G间軸距，及轉 子葉輪1 4 4與靜子葉輪1 8 4間軸距，處理〜 取體爲分十 -9« 本紙張尺度適用中國國家標準（CNS ) A4規格（210X297公釐） 47911° A7 B7 一----— --- " ------ 五、發明説明（7) 流（這些葉輪1 4 2與1 4 4及1 8 2至1 8 4待後述） Ο ' · (請先閱讀背面之注意事項再填寫本頁) 接著參考圖3說明本發明較佳例。 圖3截面圖顯示本發明例之增壓分子泵整個結構。 如圖3所示，本例增壓分子泵1 〇包含一實質圓柱形 轉子軸桿1 2，一轉子葉輪區段1 4聯接至轉子軸桿1 2 ，一靜子葉輪區段1 8由實質筒狀外殻1 6固定，一磁性 軸承2 0以磁性支承轉子軸桿1 2，及一馬達2 1產生轉 子軸桿1 2之力矩。 轉子葉輪區段1 4包含一實質筒狀本體1 4 a聯接至 轉子軸桿1 2，及四種轉子葉輪1 4 1，1 4 2，1 4 3 及1 4 4聯接至圓柱形本體1 4 a之外周。 靜子葉輪區段1 8包含四種靜子葉輪1 8 1，1 8 2 ’ 1 8 3及1 8 4固定至外殻1 6內周，以分別對應靜子 葉輪 141 ，142，143 及 144。 經濟部智慧財產局員工消費合作社印製 如圖2所示，轉子葉輪1 4 1由多數葉片1 4 1 a構 成，各葉片相對轉子軸桿1 2以預定角度傾斜，而聯接至 圓柱形本體1 4 a外周，自其徑向延伸。 各轉子葉輪142，143及144由多數葉片構成 ’一體形成於圓柱形本體1 4 a外周，與轉子葉輪1 4 1 類似’但葉片尺寸不同，且轉子葉輪1 4 2，1 4 3及 1 4 4間傾斜角不同。 如圖2所示，靜子葉輪1 8 1由多數葉片1 8 1 a構 成’各葉片傾斜方向與轉子葉輪1 4 1葉片1 4 1 a之傾 本紙張尺度適用中國國家標準（CNS ) A4規格（210X 297公釐） A7 --------B7________ 五、發明説明（8) 斜方向相反。 (請先閲讀背面之注意事項再填寫本頁) 各靜子葉輪182，183及184由多數葉片構成 ’類似靜子葉輪1 8 1 ，但葉片尺寸不同，且靜子葉輪 1 8 2，1 8 3及1 8 4間傾斜角不同。 如此建構之轉子葉輪1 4 1及1 4 4及對應靜子葉輪 1 8 1至1 8 4交互安排於垂直方向，彼此具軸距。 轉子葉輪1 4 1與靜子葉輪1 8 1間軸距，轉子葉輪 1 4 2與靜子葉輪1 8 2間軸距，與轉子葉輪1 4 3與靜 子葉輪1 8 3間軸距均定爲2 . 5 m m，故壓力不大於 2 0毫托耳之條件下氣體可處理爲分子流。 因此，轉子葉輪1 4 1與靜子葉輪1 8 1形成排氣階 段，轉子葉輪142，143與靜子葉輪182，183 形成中間階段，轉子葉輪1 4 4與靜子葉輪1 8 4形成壓 縮階段。 經濟部智慧財產局員工消費合作社印製 上述磁性軸承2 0包含徑向電磁鐵2 2，2 4及軸向 電磁鐵2 6供相對轉子軸桿1 2分別產生徑向磁力及軸向 磁力，徑向位置感應器3 0，3 2及軸向位置感應器3 4 供分別測偵轉子軸桿1 2徑向位置及軸向位置，及控制系 統3 6供回饋控制供應徑向電磁鐵2 2，2 4及軸向電磁 鐵2 6之激發電流，係根據來自徑向位置感應器3〇， 3 2及軸向位置感應器3 4之偵測訊號。 接著參考圖式說明本例增壓分子泵之操作。 增壓分子泵於操作狀態中，以磁性軸承2 0非接觸地 保持轉子軸桿1 2於預定浮動狀態，驅使馬達2 1轉動轉 -11 - 本紙張尺度適用中國國家標準（CNS ) A4規格（21〇X 297公釐） 479110 A7 _ _ B7______ 五、發明説明（9) 子軸桿1 2。 (請先閱讀背面之注意事項再填寫本頁) 各轉子葉輪1 4 1至1 4 4於靜子葉輪1 8·1至 1 8 4間轉動乃令氣體經入口 3 8吸入，壓縮’並由出口 3 9排出，如圖3所示。 本例中，因轉子葉輪1 4 1與靜子葉輪1 8 1形成之 排氣階段中及轉子葉輪1 4 2，1 4 3與靜子葉輪1 8 2 ’ 1 8 3形成之中間階段中可處理氣體流爲分子流，氣體 中分子由轉子葉輪141 ， 142及143之葉片打擊而 移向出口 3 9。 類似習知設備，對本發明實施例測試流量特性，取得 圖4實線Β所指結果。 此處本發明實施例將轉子葉輪1 4 1與靜子葉輪 1 8 1間軸距定爲2 · 5 m m，習知設備則定爲‘ 5 m m。 經濟部智慈財產局員工消費合作社印製 由測試結果可見’若流量爲1 〇 〇 〇 S C C Μ，習知 設備中壓力爲3 0毫托耳，超過所需壓力2 〇毫托耳，但 本例壓力爲1 0毫托耳。故本發明例可充分確保低壓。此 外’若流量爲1 5 0 0 S C C Μ，習知設備中壓力不小於 6〇毫托耳’本例壓力爲2 0毫托耳。故本發明例可充分 確保低壓。 如上述’即使較習知流量提高排氣量，本發明例可確 保所需壓力於1 0 - 2 0毫托耳（所需真空性），並保持 較大排氣量。 由上述設定轉子葉輪1 4, 1與靜子葉輪1 8 1間軸距 ，可於轉子葉輪1 4 1與靜子葉輪丨8 1間軸向視氣體流 本紙張尺度適用中國國家標準（CNS ) A4規格（2ι〇Χ297公釐） -12- 479110 A7 ____—__B7 五、發明説明（1() 爲分子流。 此外，上述例中，轉子葉輪丄4丄與靜子葉輪丄8丄 間軸距，轉子某輪1 4 2與靜子葉輪丨8 2間軸距，及轉 子葉輪1 4 3與靜子葉輪1 8 3間軸距均定爲2 · 5 m m ，故壓力等於或小於2 0鼋托耳之條件下氣體可視爲分子 流。 根據本發明，靜子葉輪與轉子葉輪間軸距設定値可於 正常操作時入口壓力等於或大於i 〇毫托耳條件下處理氣 體爲分子流。 因此，根據本發明，正常操作時壓力等於或大於丄〇 毫托耳之條件下氣體可處理爲分子流，排放性能良好。即 使正常操作時較習知設備提高供至真空室之氣體量，本發 明可確保所需壓力（所需真空性），並保持更大氣體流量 -----^丨卜裝--------訂-----#線 (請先閱讀背面之注意事項再填寫本頁) 經濟部智慧財產局員工消費合作社印製 本紙張尺度適用中國國家標準（CNS ) A4規格（210、Χ297公釐） -13-1T Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs -5- Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 479110 A7 B7____ 5. Description of the invention (3) Physical flow. The present invention can also be expressed as follows: That is, the booster molecular pump of the present invention is characterized by: a rotor shaft; a bearing rotatably supporting the rotor shaft; a motor rotating the rotor shaft supported by the bearing; Multi-stage rotor impellers; and multi-stage static sub-impellers are arranged between the multi-stage rotor impellers; and at least one wheelbase between one of the rotor impellers and the corresponding static sub-impeller is set according to the discharge amount under normal operation is not less than 1 0 0 0 sccm Processed gas molecular flow. One of the rotor impellers is closest to the entrance of the multi-stage rotor impeller, and the corresponding static impeller is closest to the entrance of the multi-stage rotor. One of the rotor impellers and the at least one wheelbase of the corresponding stator impeller is set according to the average free path of the molecular gas. As described above, according to the present invention, the axial distance between the stator impeller and the rotor impeller is set to be a molecular flow under the condition that the inlet pressure is equal to or greater than 10 mTorr during normal operation. Therefore, according to the present invention, the molecular gas flow can be processed under the condition that the pressure is equal to or greater than 10 mTorr under normal operation, and sufficient exhaust performance can be obtained. Even if it is known that the amount of gas supplied to the vacuum chamber is increased during normal operation, the present invention can ensure the required pressure (required vacuum) and maintain a larger gas flow. The paper size applies the Chinese National Standard (CNS) A4 specification ( 210X 297 mm) I ------ · I installed ------ order ^ (Please read the precautions on the back before filling this page) 479110 A7 B7 i. Description of the invention (4) Simple illustration of the diagram In the figure: (Please read the notes on the back before filling out this page) Figure 1 is the main part of the booster molecular pump, explaining the basic principle of the present invention; Figure 2 is an expanded view of the rotor impeller and the stator impeller, showing the main parts; Figure 3 This is a cross-sectional view of an example of a booster molecular pump of the present invention; and FIG. 4 shows a comparison table of the main components of the flow characteristics test results of the example of the present invention and conventional equipment. 141 Rotor impeller 142 Rotor impeller 14 3 Rotor impeller 1 4 4 Rotor impeller 18 1 182 Static Impeller 183 Static Impeller 184 Static Impeller Intellectual Property Bureau Employees Consumer Cooperative Cooperative Seal 10 Molecular Pump 12 Rotor Shaft 14 Rotor Impeller Section 16 Housing 1 8 Static Impeller Section 2 0 Bearing 2 1 Motor Zhang scale is applicable to Chinese National Standard (CNS) A4 specification (210X297 mm) 479110 A7 B7___ V. Description of the invention (5) 1 -4 a Body 141a Blade · (Please read the precautions on the back before filling this page) 2 2 Electromagnetic Iron 2 4 Electromagnet 3 0 Position sensor 32 Position sensor 3 4 Position sensor 2 6 Electromagnet 3 8 Inlet 3 9 Outlet The preferred embodiment will be described in detail below before explaining the embodiments of the present invention. Fig. 1 is a cross-sectional view of a main part of the present invention, and other parts are omitted to facilitate explanation of the basic principle of the present invention. FIG. 2 is an expanded view showing the relationship between the rotor impeller 1 4 1 and the static impeller 1 8 1. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. According to the above-mentioned viewpoint, as shown in FIG. 1, the wheelbase a is set between the rotor impeller 1 4 1 and at least the static impeller 1 8 closest to the entrance. The entrance can be entered during normal operation. Process gas molecular flow at a pressure of not less than 10 mTorr. If the booster molecular pump is used to discharge the gas supplied to the vacuum chamber during normal operation, the flow rate of the exhaust gas is predetermined. Therefore, the booster molecular pump must meet the conditions, that is, the predetermined exhaust volume during normal operation, and must also provide vacuum (for example, the pressure is not greater than 20 mTorr). Therefore, the present invention can be expressed as follows: Turn -8-This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) 479110 A7 __ B7______ V. Description of the invention (6) (Please read the notes on the back before filling (This page) The wheelbase between the sub-impeller 1 4 1 and at least the static sub-impeller 1 8 closest to the inlet is set to -a. It can handle gas molecular flow under normal conditions with a displacement of not less than 1000 · SCC Μ. Next, a method for setting the wheelbase a between the rotor impeller 1 41 and the stator 1 1 1 according to the above principle will be described. As mentioned above, whether the gas can be treated as a molecular flow at the wheelbase between the rotor impeller 1 41 and the stator impeller 1 81 depends on the average free path of the gas molecules. The average free path λ is expressed as the following formula (1): λ = 0 · 0 5 / pressure (mm) ...... (1) The pressure unit in formula (1) is Torr. If the average free path λ is not less than the above-mentioned distance a, then Qi ^ _ 司 * _ 王 里 is molecular flow. Next, it is explained that the pressure during the normal operation is not more than 20 milligrams, which is the molecular flow. According to the formula (1), the pressure is 20 mTorr. The employee ’s consumer cooperative industy of the Intellectual Property Bureau of the Ministry of Economic Affairs has a path λ of 2.5mm (person = 2.5mm). Therefore, if the axial distance a between the rotor impeller 1 4 1 and the stator impeller 丨 s ^ ^ σ σ 1 is set to be not more than 2.5 mm, then the pressure can be treated as molecular flow under the condition of busy pressure. In addition, the wheelbase between the rotor wheel 1 4 2 and the stator wheel ^ 8 2 can be set similarly, the wheelbase between the rotor wheel 1 4 3 and the stator wheel 1 8 3 _ ^ _ G, and the rotor wheel 1 4 4 and the stator wheel 1 8 4 wheelbases, processing ~ minus 10-9 «This paper size applies Chinese National Standard (CNS) A4 specifications (210X297 mm) 47911 ° A7 B7 One -------- --- "- ---- V. Description of the invention (7) Flow (these impellers 1 4 2 and 1 4 4 and 1 8 2 to 1 8 4 will be described later) 〇 '· (Please read the precautions on the back before filling this page) Next A preferred embodiment of the present invention will be described with reference to FIG. 3. Fig. 3 is a cross-sectional view showing the entire structure of a booster molecular pump according to an example of the present invention. As shown in FIG. 3, the booster molecular pump 10 of this example includes a substantially cylindrical rotor shaft 12, a rotor impeller section 14 is coupled to the rotor shaft 12, and a static impeller section 18 is composed of a substantial cylinder. The shell 16 is fixed, a magnetic bearing 20 magnetically supports the rotor shaft 12 and a motor 21 generates a torque of the rotor shaft 12. The rotor wheel section 14 includes a substantially cylindrical body 1 4 a coupled to the rotor shaft 12 and four rotor wheels 1 4 1, 1 4 2, 1 4 3 and 1 4 4 coupled to the cylindrical body 1 4 a outside the week. The static impeller section 18 includes four types of static impellers 1 8 1, 1 8 2 ′ 1 8 3 and 1 8 4 fixed to the inner periphery of the casing 16 to correspond to the static impellers 141, 142, 143, and 144, respectively. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, as shown in Figure 2, the rotor impeller 1 4 1 is composed of a large number of blades 1 4 1 a, and each blade is inclined at a predetermined angle with respect to the rotor shaft 12 and is coupled to the cylindrical body 1 4 a outer periphery, extending radially from it. Each of the rotor impellers 142, 143, and 144 is composed of a plurality of blades, which are integrally formed on the outer periphery of the cylindrical body 1 4 a, similar to the rotor impeller 1 4 1, but with different blade sizes, and the rotor impellers 1 4 2, 1 4 3, and 1 4 The 4 tilt angles are different. As shown in FIG. 2, the static impeller 1 8 1 is composed of a plurality of blades 1 8 1 a. The inclination direction of each blade and the inclination of the rotor impeller 1 4 1 blade 1 4 1 a are in accordance with Chinese National Standard (CNS) A4 specifications ( 210X 297 mm) A7 -------- B7________ 5. Description of the invention (8) The oblique direction is opposite. (Please read the precautions on the back before filling in this page) Each of the stator blades 182, 183 and 184 is composed of most blades. 'Similar to the blade rotor 1 8 1, but the blade size is different, and the blade rotors 1 8 2, 1 8 3 and 1 8 4 different inclination angles. The rotor impellers 1 4 1 and 1 4 4 thus constructed and the corresponding static sub-impellers 1 8 1 to 1 8 4 are arranged alternately in a vertical direction with a wheelbase from each other. The wheelbase between the rotor wheel 1 4 1 and the stator wheel 1 8 1, the wheelbase between the rotor wheel 1 4 2 and the stator wheel 1 8 2, and the wheelbase between the rotor wheel 1 4 3 and the stator wheel 1 8 3 are both set to 2. 5 mm, so the gas can be processed into molecular flow under the pressure of not more than 20 millitorr. Therefore, the rotor impeller 1 41 and the stator impeller 1 81 form an exhaust phase, the rotor impellers 142, 143 and the stator impellers 182, 183 form an intermediate stage, and the rotor impeller 1 4 4 and the stator impeller 1 8 4 form a compression stage. The above-mentioned magnetic bearing 20 is printed by the employee's consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, which includes radial electromagnets 2 2, 2 4 and axial electromagnets 2 6 for generating radial and axial magnetic forces with respect to the rotor shaft 12 respectively. The position sensor 3 0, 3 2 and the axial position sensor 3 4 are used to detect the radial and axial positions of the rotor shaft 12 and the control system 3 6 and the radial solenoid 2 2 is provided for feedback control. The excitation currents of 24 and the axial electromagnet 26 are based on the detection signals from the radial position sensor 30, 32 and the axial position sensor 34. Next, the operation of the booster molecular pump of this example will be described with reference to the drawings. In the operating state, the booster molecular pump maintains the rotor shaft 1 2 non-contact with magnetic bearings 20 in a predetermined floating state, and drives the motor 21 to rotate -11-This paper size applies to Chinese National Standard (CNS) A4 specifications ( 21〇X 297 mm) 479110 A7 _ _ B7______ V. Description of the invention (9) Sub-shaft 12. (Please read the precautions on the back before filling in this page.) Each rotor impeller 1 4 1 to 1 4 4 rotates between the static impeller 1 8 · 1 to 1 8 4 so that the gas is sucked in through the inlet 3 8 and compressed 'and exit from the outlet 3 9 discharge, as shown in Figure 3. In this example, gas can be processed in the exhaust phase formed by the rotor impeller 1 4 1 and the stator impeller 1 8 1 and in the intermediate stage formed by the rotor impeller 1 4 2, 1 4 3 and the stator impeller 1 8 2 '1 8 3 The flow is a molecular flow, and the molecules in the gas are struck by the blades of the rotor impellers 141, 142, and 143 and move to the outlet 39. Similar to the conventional device, the flow characteristics of the embodiment of the present invention were tested to obtain the result indicated by the solid line B in FIG. 4. Here, in the embodiment of the present invention, the wheelbase between the rotor impeller 1 41 and the stator impeller 1 81 is set to 2.5 mm, and the conventional device is set to ‘5 mm. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs, it can be seen from the test results that 'If the flow is 1000 SCC Μ, the pressure in the conventional device is 30 mTorr, which exceeds the required pressure by 20 mTorr. Example pressure is 10 mTorr. Therefore, the example of the present invention can fully ensure the low pressure. In addition, if the flow rate is 1 500 S C C M, the pressure in the conventional device is not less than 60 mTorr. In this example, the pressure is 20 mTorr. Therefore, the example of the present invention can sufficiently ensure the low pressure. As mentioned above, even if the discharge volume is increased compared to the conventional flow rate, the example of the present invention can ensure that the required pressure is between 10 and 20 millitorr (required vacuum) and maintain a large discharge volume. Based on the above, the wheelbase between the rotor impeller 1 4, 1 and the stator impeller 1 8 1 can be set between the rotor impeller 1 4 1 and the stator impeller 丨 8 1 in the axial direction depending on the gas flow. The paper size applies the Chinese National Standard (CNS) A4 specification. (2ι〇 × 297 mm) -12- 479110 A7 ____—__ B7 V. Description of the invention (1 () is molecular flow. In addition, in the above example, the wheelbase between the rotor impeller 丄 4 丄 and the stator impeller 丄 8 丄 is The wheelbase between the wheel 1 4 2 and the static impeller 丨 8 2 and the wheelbase between the rotor impeller 1 4 3 and the static impeller 1 8 3 are set to 2 · 5 mm, so the pressure is equal to or less than 20 0 Torr Gas can be regarded as molecular flow. According to the present invention, the axial distance setting between the stator impeller and the rotor impeller can be handled as a molecular flow under the condition that the inlet pressure is equal to or greater than 100 millitorr during normal operation. Therefore, according to the present invention, normal The gas can be treated as molecular flow under the condition that the pressure during operation is equal to or greater than 100 millitorr, and the discharge performance is good. Even if the amount of gas supplied to the vacuum chamber is increased compared with conventional equipment during normal operation, the invention can ensure the required pressure Required vacuum), and ensure Larger gas flow ----- ^ 丨 Bulk installation -------- Order ----- # line (Please read the precautions on the back before filling out this page) Intellectual Property Bureau, Ministry of Economic Affairs, Consumer Consumption Cooperative The printed paper size is applicable to China National Standard (CNS) A4 (210, X297 mm) -13-