さらに、ハウジング２には、第１シール部材５Ａと、第２シール部材５Ｂによって囲まれた冷却用空間Ｍに冷却用流体を通過させるための流体通路２３,２３が設けられている。これにより、冷却用空間Ｍに触れているハウジング２の内周面（内壁）、シール固定部材３５の外周面、第１シール部材５Ａ,第２シール部材５Ｂを冷却することができる。
Further, the housing 2 is provided with fluid passages 23 and 23 for allowing the cooling fluid to pass through the cooling space M surrounded by the first seal member 5A and the second seal member 5B . Thereby, the inner peripheral surface (inner wall ) of the housing 2 touching the cooling space M, the outer peripheral surface of the seal fixing member 35, the first seal member 5A, and the second seal member 5B can be cooled.
実施形態１においては、シャフト８１が回転すると、接触式シールである第１シール部材５Ａ及び第２シール部材５Ｂと、ハウジング２の貫通孔２２との間で摩擦が生じる。第１シール部材５Ａ及び第２シール部材５Ｂは上述したように樹脂またはゴムで形成されているため、第１シール部材５Ａ及び第２シール部材５Ｂの熱伝導率は、金属で形成された他の部材と比較して１／１０００から１／１００程度である。したがって、第１シール部材５Ａ,第２シール部材５Ｂおよび貫通孔２２の間で生じた摩擦熱の大部分は、貫通孔２２側に伝わり、回転部材３の温度上昇は抑制される。可動部材３３と貫通孔２２との間には、高真空環境である内部空間Ｖに繋がる隙間が設けられているため、実施形態１における貫通孔２２の熱は、可動部材３３側へ伝熱しにくくなっている。一方、貫通孔２２の熱は、フランジ部２１Ｂから筒状部２１Ａに伝熱する。冷却用空間Ｍ及び外部空間Ｅでは、高真空環境である内部空間Ｖと異なり空気の対流があるため、外部空間Ｅの空気と外側部材２１の外表面との間で熱伝達が生じやすい。これにより、第１シール部材５Ａ及び第２シール部材５Ｂとの摩擦によってハウジング２の貫通孔の内壁に生じた熱の放熱が促進される。このため、第１シール部材５Ａ及び第２シール部材５Ｂの温度上昇が抑制されるので、第１シール部材５Ａ及び第２シール部材５Ｂの熱膨張が抑制される。したがって、第１シール部材５Ａ及び第２シール部材５Ｂの貫通孔２２に対する接触圧の増加が抑制されることで、第１シール部材５Ａ及び第２シール部材５Ｂの摩耗の進行が抑制される。
よって、シール構造１は、接触式シールである第１シール部材５Ａ及び第２シール部材５Ｂの交換頻度を低減することができる。
In the first embodiment, when the shaft 81 rotates, friction occurs between the first seal member 5 </ b> A and the second seal member 5 </ b> B, which are contact seals, and the through hole 22 of the housing 2. Since the first seal member 5A and the second seal member 5B are made of resin or rubber as described above, the thermal conductivity of the first seal member 5A and the second seal member 5B is other than that made of metal. It is about 1/1000 to 1/100 compared with the member. Therefore, most of the frictional heat generated between the first seal member 5A, the second seal member 5B and the through hole 22 is transmitted to the through hole 22 side, and the temperature rise of the rotating member 3 is suppressed. Since a gap is provided between the movable member 33 and the through hole 22 so as to connect to the internal space V that is a high vacuum environment, the heat of the through hole 22 in the first embodiment is difficult to transfer to the movable member 33 side. It has become. On the other hand, the heat of the through hole 22 is transferred from the flange portion 21B to the cylindrical portion 21A. In the cooling space M and the external space E, unlike the internal space V which is a high vacuum environment, there is convection of air, so heat transfer is likely to occur between the air in the external space E and the outer surface of the outer member 21. Thus, the heat radiation of the heat generated on the inner wall of the through hole of the housing 2 is accelerated by the friction between the first seal member 5A and the second seal member 5B. For this reason, since the temperature rise of 5 A of 1st seal members and the 2nd seal member 5B is suppressed, the thermal expansion of 5 A of 1st seal members and the 2nd seal member 5B is suppressed. Accordingly, the increase in the contact pressure of the first seal member 5A and the second seal member 5B with respect to the through hole 22 is suppressed, so that the progress of wear of the first seal member 5A and the second seal member 5B is suppressed.
Therefore, the seal structure 1 can reduce the replacement frequency of the first seal member 5A and the second seal member 5B which are contact seals.
なお、シール構造１は、回転部材３がハウジング２に対して回転運動するとともに、軸方向に移動するため、ハウジング２の貫通孔２２の、第１シール部材５Ａとの摺接面の軸方向長さを、回転部材３のハウジング２に対する軸方向ストロークよりも大きくする。同様に、貫通穴２２の、第２シール部材５Ｂとの摺接面の軸方向長さも、回転部材３のハウジング２に対する軸方向ストロークよりも大きくする。これにより、回転部材３が軸方向に所定の距離移動する全域において第１シール部材５Ａによって内部空間Ｖを外部空間Ｅに対して密封することができる。
In the seal structure 1, since the rotary member 3 rotates with respect to the housing 2 and moves in the axial direction, the axial length of the sliding contact surface of the through hole 22 of the housing 2 with the first seal member 5A. This is made larger than the axial stroke of the rotating member 3 with respect to the housing 2. Similarly, the axial length of the sliding contact surface of the through hole 22 with the second seal member 5 </ b> B is also made larger than the axial stroke of the rotating member 3 with respect to the housing 2. Thereby, the internal space V can be sealed with respect to the external space E by the first seal member 5 </ b> A in the entire region in which the rotating member 3 moves in the axial direction by a predetermined distance.
以上、実施形態１について説明したが、前述した内容により限定されるものではない。また、実施形態１の要旨を逸脱しない範囲で構成要素の種々の省略、置換および変更のうち少なくとも１つを行うことができる。
例えば、上述の実施形態１では、第２シール部材５Ｂは、第１シール部材５Ａと同一のものを用いているが、同様の構成であれば、形状や大きさは異なっていても良い。例えば、シャフト８１に対して、回転部材３の外径を大きく、又は小さく形成し、それに合わせて第１シール部材５Ａに対して大きい、又は小さい第２シール部材５Ｂを使用しても良い。
Although the first embodiment has been described above, the present invention is not limited to the contents described above. In addition, at least one of various omissions, replacements, and changes of the components can be made without departing from the gist of the first embodiment.
For example, in the above-described first embodiment, the second seal member 5 B, although using the same as the first sealing member 5 A, if the same structure, shape and size may differ . For example, the shaft 81, increasing the outer diameter of the rotating member 3, or less formed, be used accordingly large relative to the first sealing member 5 A or less second seal member 5 B .