JPH0756276B2 - Oil-free screw type vacuum pump - Google Patents
Oil-free screw type vacuum pumpInfo
- Publication number
- JPH0756276B2 JPH0756276B2 JP60223966A JP22396685A JPH0756276B2 JP H0756276 B2 JPH0756276 B2 JP H0756276B2 JP 60223966 A JP60223966 A JP 60223966A JP 22396685 A JP22396685 A JP 22396685A JP H0756276 B2 JPH0756276 B2 JP H0756276B2
- Authority
- JP
- Japan
- Prior art keywords
- vacuum pump
- gas
- oil
- rotor chamber
- screw
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000001816 cooling Methods 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 238000002347 injection Methods 0.000 claims description 12
- 239000007924 injection Substances 0.000 claims description 12
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 10
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
Landscapes
- Applications Or Details Of Rotary Compressors (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、ロータ室内に冷却用等の油等を注入しないオ
イルフリー形スクリュ式真空ポンプに関するものであ
る。Description: TECHNICAL FIELD The present invention relates to an oil-free screw vacuum pump that does not inject cooling oil or the like into a rotor chamber.
（従来技術） 従来、真空ポンプとして、例えば水封式真空ポンプ（特
公昭54−37693号公報），高真空ポンプ（特公昭57−599
20号公報）,2軸式真空ポンプ（特開昭59−185889号公
報）が公知である。(Prior Art) Conventionally, as a vacuum pump, for example, a water-sealed vacuum pump (Japanese Patent Publication No. 54-37693), a high vacuum pump (Japanese Patent Publication No. 57-599).
20) and a two-axis vacuum pump (Japanese Patent Laid-Open No. 59-185889).
これらの真空ポンプはガスを吸込み、圧縮状態で吐出す
るという点からすれば圧縮機と機能的に共通している。
しかしながら、留意すべきは一般的に圧縮機に比べて真
空ポンプで取扱うガスは低圧であるため、吸込ガスと吐
出ガスの圧力比が大きくなり、ガスの断熱圧縮に伴う温
度上昇が著しいことである。These vacuum pumps are functionally common to the compressors in that they suck gas and discharge it in a compressed state.
However, it should be noted that the gas handled by the vacuum pump is generally lower in pressure than the compressor, so the pressure ratio between the suction gas and the discharge gas becomes large, and the temperature rise due to the adiabatic compression of the gas is remarkable. .
例えば、通常の空気圧縮機の吸込圧，吐出圧がOatg,7at
gであるのに対して、真空ポンプでは吐出圧が通常大気
圧（1.033ata）で、吸込圧が0.1ataあるいは0.01ata程
度である。For example, the suction pressure and discharge pressure of a normal air compressor are Oatg, 7at
In contrast to g, in a vacuum pump, the discharge pressure is usually atmospheric pressure (1.033ata) and the suction pressure is about 0.1ata or 0.01ata.
吸込圧をP1、吐出圧をP2、吸込ガス温度をTs（゜Ｋ），
吐出ガス温度をTd（゜Ｋ），ポリトロープ指数をｋとす
ると、断熱圧縮の場合Tdは大略次式で表される。Suction pressure is P1, discharge pressure is P2, suction gas temperature is Ts (° K),
When the discharge gas temperature is Td (° K) and the polytropic index is k, Td is approximately represented by the following equation in the case of adiabatic compression.
Td＝Ts（P2/P1）（ｋ−１）/k Tsを常温（即ち、273＋30゜Ｋ）,k＝0.4として、この式
により上記各場合におけるTdを計算すると以下のように
なる。When Td = Ts (P2 / P1) (k-1) / kTs is set at room temperature (that is, 273 + 30 ° K) and k = 0.4, Td in each of the above cases is calculated by this formula as follows.
このように、空気圧縮機に比べて真空ポンプでの仕事量
は小さいが、真空ポンプでの温度上昇の方がかなり大き
くなる。 As described above, the work amount in the vacuum pump is smaller than that in the air compressor, but the temperature rise in the vacuum pump is considerably large.
そこで、上記水封式真空ポンプや高真空ポンプでは、ガ
ス温度の上昇を防ぐために、ガスを水あるいは油に直接
接触させた状態で吸込口から吐出口に至らせるようにす
ることよりガスおよび装置を冷却するようにしてある。Therefore, in the above-mentioned water-sealed vacuum pump and high vacuum pump, in order to prevent the temperature of the gas from rising, the gas and the device are made to reach from the suction port to the discharge port while the gas is in direct contact with water or oil. Is designed to be cooled.
しかしながら、この種の真空ポンプによれば、吸込側に
水、或は油のにおいが漏れ出したり、停電時等の場合の
ように装置が急に停止した場合には水や油が吸込側に逆
流する事態も起こり得る。このため、不純物の混入が許
されない半導体の製造部門や、これに加えて、特に匂い
の発生を嫌う食品産業関係（例えば真空パック）ではそ
の使用はできない。However, according to this type of vacuum pump, when the odor of water or oil leaks to the suction side, or when the device suddenly stops as in the case of a power failure, etc., water or oil will flow to the suction side. The situation of backflow may occur. For this reason, it cannot be used in the semiconductor manufacturing department where impurities cannot be mixed in, or in addition to this, especially in the food industry relations where the generation of odor is disliked (for example, vacuum packaging).
これに対して、上記２軸式真空ポンプにはオイルフリー
形（本明細書では、水および油を真空引きするガスに接
触させる状態では用いない形式のものをいう。）のもの
がある。On the other hand, there is an oil-free type (in this specification, a type that is not used in a state where water and oil are brought into contact with a gas for vacuuming) in the two-shaft type vacuum pump.
しかしながら、この形式の真空ポンプではロータ同志を
無接触に保つ必要性から構造上ロータ間の隙間が大きく
ならざるを得ない。このため、この真空ポンプは中真空
領域（103〜1Torr）で使えても、低真空領域（１〜760T
orr）ではロータ間からのガス漏れが増大し、ガス温度
の上昇が著しくなり、この領域での使用には適していな
い。However, in this type of vacuum pump, the gap between the rotors is unavoidably large because of the necessity to keep the rotors in contact with each other. Therefore, even if this vacuum pump can be used in the medium vacuum range (10 3 to 1 Torr), it can be used in the low vacuum range (1 to 760 T).
orr) is not suitable for use in this region because gas leakage between rotors increases and the gas temperature rises significantly.
このため、これまで単段で低真空域から高真空域までの
使用に適したオイルフリー形真空ポンプの開発が望まれ
ていた。Therefore, it has been desired to develop a single-stage oil-free vacuum pump suitable for use in a low vacuum region to a high vacuum region.
ところで、上記のように圧縮機が真空ポンプと機能的に
共通する点を有していることから本発明者らはロータ間
からのガス漏れが小さいオイルフリー形スクリュ式圧縮
機本体を真空ポンプとして使用する試みを種々行なっ
た。By the way, as described above, since the compressor has a point that is functionally common to the vacuum pump, the present inventors have used the oil-free type screw compressor main body, which has a small gas leakage between rotors, as a vacuum pump. Various attempts were made to use it.
しかしながら、スクリュ式圧縮機本体をそのまま真空ポ
ンプとして使用するだけでは、上記の数値計算例にも示
されるように、大気圧以上の領域と異なり、真空領域で
はガス温度の上昇が著しいため、実用としては供し得な
いという問題があった。However, if the screw type compressor body is used as it is as a vacuum pump, as shown in the above numerical calculation example, the gas temperature rises remarkably in the vacuum region, which is different from the atmospheric pressure region or higher. There was a problem that he could not serve.
なお、一般的にオイルフリー形スクリュ式圧縮機本体の
ケーシングは水冷用のジャケットを有しており、断熱圧
縮されたロータ室内のガスおよびスクリュロータを水冷
するようになっている。しかしながら、これを真空ポン
プとして使用した場合、ロータ室内のガスが希薄で、熱
を伝える媒体が少なくなるため水冷の効果は殆どなく、
これが温度上昇の一因にもなっている。In general, the casing of the oil-free type screw compressor main body has a jacket for water cooling, so that the gas in the rotor chamber and the screw rotor that have been adiabatically compressed are cooled with water. However, when this is used as a vacuum pump, the gas in the rotor chamber is lean and the medium that transfers heat is small, so there is almost no effect of water cooling,
This also contributes to the temperature rise.
（発明の目的） 本発明は、上記従来の要望および問題点に鑑みてなされ
たもので、その目的は低真空域から高真空域まで単段で
真空引きできるオイルフリー形スクリュ式真空ポンプを
提供することにある。(Object of the Invention) The present invention has been made in view of the above-mentioned conventional demands and problems, and an object thereof is to provide an oil-free screw vacuum pump capable of vacuuming in a single stage from a low vacuum region to a high vacuum region. To do.
（発明の構成） 上記目的を達成するために、本発明は、互いに噛み合う
雌雄一対のスクリュロータと、一方が吸込口に、他方が
吐出口に開口したロータ室を有し、このロータ室内にス
クリュロータを回転可能に収納し、上記ロータ室並びに
吐出口側軸受部を囲むように設けられた水冷用ジャケッ
トを有するケーシングとからなるオイルフリー形スクリ
ュ式真空ポンプにおいて、一端が、上記ロータ室の端面
を除く内周面に開口し、かつ上記ロータ室内の吸込口お
よび吐出口とは連通することがない空間に面するととも
に、周囲を水冷用ジャケットで囲まれた空気噴射孔を形
成した。(Structure of the Invention) In order to achieve the above object, the present invention has a pair of male and female screw rotors that mesh with each other, and a rotor chamber in which one is opened at a suction port and the other is opened at a discharge port. An oil-free screw vacuum pump comprising a rotor rotatably housed and a casing having a water-cooling jacket provided so as to surround the rotor chamber and a discharge port side bearing portion, one end of which is an end surface of the rotor chamber. And an air injection hole surrounded by a water-cooling jacket. The air injection hole is formed on the inner peripheral surface of the rotor chamber and faces a space that does not communicate with the suction port and the discharge port in the rotor chamber.
（実施例） 次に、本発明の一実施例を図面にしたがって説明する。(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.
第１図，第２図は本発明に係るオイルフリー形スクリュ
式真空ポンプを示し、オイルフリー形のスクリュ式ポン
プ本体１のケーシング２に、これを貫通する空気噴射孔
３を穿設して形成してある。即ち、スクリュ式ポンプ本
体１のケーシング２は水冷用ジャケット４を有するとと
もに、一方が吸込口５に、他方が吐出口６に開口したロ
ータ室７を有し、このロータ室７内に、互いに噛み合う
雌雄一対のスクリュロータ８が回転可能に収納してあ
る。そして、このスクリュロータ８の各歯溝部９は回転
して位置を変えることにより吸込口５に開口した状態、
吸込口５および吐出口６からは遮断されたガス閉込み状
態、吐出口６に開口した状態の３つの状態を順次繰返
し、各状態に対応してガス吸込み空間，圧縮（閉込み）
空間，吐出空間となる。1 and 2 show an oil-free screw vacuum pump according to the present invention, which is formed by forming an air injection hole 3 through the casing 2 of an oil-free screw pump main body 1. I am doing it. That is, the casing 2 of the screw type pump main body 1 has a water cooling jacket 4, one has a rotor chamber 7 opened to the suction port 5 and the other to the discharge port 6, and meshes with each other in the rotor chamber 7. A pair of male and female screw rotors 8 are rotatably housed. Then, the tooth groove portions 9 of the screw rotor 8 are rotated to change their positions so as to be opened to the suction port 5,
Three states, that is, a gas closed state in which the gas is blocked from the suction port 5 and the discharge port 6 and a state in which the gas is opened to the discharge port 6 are sequentially repeated, and a gas suction space and a compression (closed) corresponding to each state.
Space and discharge space.
したがって、このようなスクリュ式ポンプ本体１特有の
構造上の特徴からロータ室７の壁部には常時ガス閉込み
状態にあり、吸込口５および吐出口６とは連通すること
がないロータ室７内の空間（ガス閉込み空間）である歯
溝部に面した部分があり、上記空気噴射孔３はこの部分
に穿設してある。Therefore, due to such a structural characteristic peculiar to the screw type pump body 1, the wall of the rotor chamber 7 is always in a gas-closed state, and the rotor chamber 7 that is not in communication with the suction port 5 and the discharge port 6 is in communication. There is a portion facing the tooth space, which is an internal space (gas confining space), and the air injection hole 3 is formed in this portion.
そして、このように空気噴射孔３を設けることにより大
気圧以下の状態にあるガス閉込み空間に、この空間内の
圧縮ガスよりもかなり低温（即ち、常温）の空気を圧力
差のみを利用して供給し、圧縮ガスを冷却するようにな
っている。さらに、空気噴射孔３の周囲は水冷用ジャケ
ット４になっており、これにより供給空気を冷却して、
上記冷却効果を高めるようにしてある。By providing the air injection holes 3 in this manner, the air at a temperature significantly lower than the compressed gas in the space (that is, room temperature) is used in the gas confined space under the atmospheric pressure by using only the pressure difference. The compressed gas is cooled by supplying the compressed gas. Further, around the air injection hole 3 is a water cooling jacket 4, which cools the supply air,
The cooling effect is enhanced.
通常、高圧ガスを発生させるために用いるスクリュ式ポ
ンプ本体に空気噴射孔３のような孔を設けても大気圧の
方が低圧になるので圧力差のみによる空気の供給は行え
ない。また何らかの装置を使って強制的にガス閉込み空
間内に空気を供給できても消費動力の増大を招くことに
なるので、斯かる供給は好ましくない。Normally, even if holes such as the air injection holes 3 are provided in the screw type pump body used for generating the high-pressure gas, the atmospheric pressure becomes lower, so that the air cannot be supplied only by the pressure difference. Further, even if the air can be forcibly supplied into the gas confined space by using some kind of device, the power consumption will increase, and therefore such supply is not preferable.
しかしながら、上記のように真空ポンプとして使用する
場合はガス閉込み空間内は大気圧にある吐出口６と連通
することはなく、常に真空域にあるため、何ら空気供給
のための他の装置は必要としない。また真空ポンプでは
ガス閉込み空間内は真空域にあり、ガス圧縮に要する動
力は殆ど無視できる程度で、この空間内に空気を供給す
ることによる消費動力の増大は余り問題にはならない。However, when used as a vacuum pump as described above, the gas confined space does not communicate with the discharge port 6 at atmospheric pressure and is always in a vacuum region, so that no other device for air supply is provided. do not need. Further, in the vacuum pump, the gas confined space is in a vacuum region, and the power required for gas compression is almost negligible, and the increase in power consumption by supplying air into this space does not pose a problem.
また、ガス閉込み空間に吸込まれた空気は熱を伝える媒
体にもなり、真空状態では水冷用ジャケット４によるガ
スおよびスクリュロータ８の冷却は殆ど効果がなかった
のに対し、これらの水冷も効果的となり、上記空気と圧
縮ガスとの温度差による冷却効果と相俟って空気による
圧縮ガスの冷却が効率よく行われる。Further, the air sucked into the gas confined space also serves as a medium for transmitting heat, and cooling of the gas and the screw rotor 8 by the water cooling jacket 4 had little effect in the vacuum state, whereas these water cooling also had effect. Therefore, in combination with the cooling effect due to the temperature difference between the air and the compressed gas, the compressed gas is efficiently cooled by the air.
さらに、スクリュ式ポンプ本体１固有の特徴に起因する
ものであるが、ガス閉込み空間は吸込口５と連通するこ
とがないため、この空間内に空気を供給しても、吸込口
５側の真空度には全く影響を与えることはない。Further, due to the characteristics peculiar to the screw type pump main body 1, since the gas confining space does not communicate with the suction port 5, even if air is supplied into this space, the suction port 5 side It has no effect on the degree of vacuum.
なお、上記実施例において空気噴射孔３からの空気の供
給量を調整する場合には、例えば空気噴射孔３の入口部
にニードル弁のような流量調整手段を設けることもでき
る。When adjusting the amount of air supplied from the air injection hole 3 in the above embodiment, a flow rate adjusting means such as a needle valve may be provided at the inlet of the air injection hole 3, for example.
（発明の効果） 以上の説明より明らかなように、本発明によればオイル
フリー形スクリュ式真空ポンプにおいて、一端が、上記
ロータ室の端面を除く内周面に開口し、かつ上記ロータ
室内の吸込口および吐出口とは連通することがない空間
に面するとともに、周囲を水冷用ジャケットで囲まれた
空気噴射孔を形成してある。(Effects of the Invention) As is apparent from the above description, according to the present invention, in the oil-free screw vacuum pump, one end is open to the inner peripheral surface excluding the end surface of the rotor chamber and the inside of the rotor chamber is An air injection hole is formed which faces a space that does not communicate with the suction port and the discharge port and is surrounded by a water cooling jacket.
このため、ガス閉込み空間内は、大気圧にある吐出口と
連通することなく、かつ常に真空域にあるという上記ス
クリュ式ポンプ本体固有の特徴を有効に生かすことがで
きる。また、上述したように、真空状態では熱を伝える
媒体が少なくなる故に、水冷用ジャケットによるガスお
よびスクリュロータの冷却は殆ど効果がなく、ロータ
室，スクリュロータ等の温度上昇を招くのに対し、本発
明の場合、ガス閉込み空間に吸込まれた空気は熱を伝え
る媒体にもなり、水冷用ジャケットに熱を逃がし、かつ
上記空間内への流入過程の空気は水冷用ジャケットによ
り冷却され、水冷も効果的となり、上記空気と圧縮ガス
との温度差による冷却効果と相俟って空気による圧縮ガ
スの冷却が効率よく行われる。即ち、冷却用空気導入の
ために別途装置を設けることなく、また何等配管を要す
ることなく、ガス閉込み空間内に、圧縮された真空引き
ガスに比べて低温の空気を供給して、簡単な構成で効率
よく圧縮ガスを冷却することができ、スクリュロータ間
の隙間を小さく保ったままで真空引きできる効果、単段
で低真空から高真空まで幅広い領域にわたって使用する
ことができる。Therefore, it is possible to effectively utilize the characteristic feature of the screw type pump body described above that the gas confined space does not communicate with the discharge port at atmospheric pressure and is always in the vacuum region. Further, as described above, since the medium that transfers heat is reduced in the vacuum state, the cooling of the gas and the screw rotor by the water cooling jacket has almost no effect, and the temperature of the rotor chamber, the screw rotor, etc., rises. In the case of the present invention, the air sucked into the gas confined space also serves as a medium for transferring heat, releases the heat to the water cooling jacket, and the air in the process of flowing into the space is cooled by the water cooling jacket and cooled by the water cooling jacket. Is also effective, and in combination with the cooling effect due to the temperature difference between the air and the compressed gas, the compressed gas is efficiently cooled by the air. That is, without providing a separate device for introducing the cooling air, and without requiring any piping, a low temperature air is supplied to the gas confined space as compared with the compressed vacuum gas, and a simple With the configuration, the compressed gas can be efficiently cooled, and the vacuum can be drawn while keeping the gap between the screw rotors small. It can be used in a wide range from low vacuum to high vacuum in a single stage.
また、オイルフリー形であるため、用途の制限なしに使
用できるという効果を奏する。Further, since it is an oil-free type, it has an effect that it can be used without limitation of its use.
第１図は本発明に係るオイルフリー形スクリュ式真空ポ
ンプの横断面図、第２図は第１図のＩ−Ｉ線断面図であ
る。 １……スクリュ式ポンプ本体、２……ケーシング、３…
…空気噴射孔、５……吸込口、６……吐出口、７……ロ
ータ室、８……スクリュロータ、９……歯溝部。1 is a cross-sectional view of an oil-free type screw vacuum pump according to the present invention, and FIG. 2 is a cross-sectional view taken along the line I-I of FIG. 1 ... Screw type pump body, 2 ... Casing, 3 ...
... Air injection hole, 5 ... Suction port, 6 ... Discharge port, 7 ... Rotor chamber, 8 ... Screw rotor, 9 ... Tooth groove.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭59−79093（ＪＰ，Ａ) 特開 昭59−115489（ＪＰ，Ａ) 特開 昭56−75994（ＪＰ，Ａ) 石井博著「真空技術講座２真空ポンプ」 日刊工業新聞社（昭40−２−25）Ｐ．84〜 85 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 59-79093 (JP, A) JP 59-115489 (JP, A) JP 56-75994 (JP, A) Hiroshi Ishii "Vacuum Technical lecture 2 vacuum pump "Nikkan Kogyo Shimbun (sho 40-2-25) 84 ~ 85
Claims (1)
と、一方が吸込口に、他方が吐出口に開口したロータ室
を有し、このロータ室内にスクリュロータを回転可能に
収納し、上記ロータ室並びに吐出口側軸受部を囲むよう
に設けられた水冷用ジャケットを有するケーシングとか
らなるオイルフリー形スクリュ式真空ポンプにおいて、
一端が、上記ロータ室の端面を除く内周面に開口し、か
つ上記ロータ室内の吸込口および吐出口とは連通するこ
とがない空間に面するとともに、周囲を水冷用ジャケッ
トで囲まれた空気噴射孔を形成したことを特徴とするオ
イルフリー形スクリュ式真空ポンプ。1. A pair of male and female screw rotors meshing with each other, and a rotor chamber, one of which is opened at a suction port and the other of which is opened at a discharge port. The screw rotor is rotatably accommodated in the rotor chamber. In an oil-free screw vacuum pump consisting of a casing having a water cooling jacket provided so as to surround the outlet side bearing portion,
Air whose one end opens to the inner peripheral surface excluding the end surface of the rotor chamber and faces a space that does not communicate with the suction port and the discharge port in the rotor chamber, and whose circumference is surrounded by a water cooling jacket An oil-free screw type vacuum pump characterized by forming injection holes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60223966A JPH0756276B2 (en) | 1985-10-07 | 1985-10-07 | Oil-free screw type vacuum pump |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60223966A JPH0756276B2 (en) | 1985-10-07 | 1985-10-07 | Oil-free screw type vacuum pump |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6282295A JPS6282295A (en) | 1987-04-15 |
| JPH0756276B2 true JPH0756276B2 (en) | 1995-06-14 |
Family
ID=16806475
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60223966A Expired - Fee Related JPH0756276B2 (en) | 1985-10-07 | 1985-10-07 | Oil-free screw type vacuum pump |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0756276B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6412092A (en) * | 1987-07-01 | 1989-01-17 | Kobe Steel Ltd | Vacuum pump of screw type |
| CN105971882A (en) * | 2016-07-12 | 2016-09-28 | 合肥新沪屏蔽泵有限公司 | Novel double-screw vacuum pump |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5675994A (en) * | 1979-11-21 | 1981-06-23 | Hitachi Ltd | Multieffect screw compressor |
| JPS59115489A (en) * | 1982-12-23 | 1984-07-03 | Unozawagumi Tekkosho:Kk | Counter-flow cooling system multistage root type vacuum pump |
-
1985
- 1985-10-07 JP JP60223966A patent/JPH0756276B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| 石井博著「真空技術講座２真空ポンプ」日刊工業新聞社（昭４０−２−２５）Ｐ．８４〜８５ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6282295A (en) | 1987-04-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |