KR20100067632A - Rotary vacuum pump - Google Patents

Abstract

PURPOSE: A rotary vacuum pump is provided to smoothly re-start regardless of the deposition of foreign material which is stacked in the inside of a pump room. CONSTITUTION: A rotary vacuum pump comprises: a housing(1); a pump room(10,11,12,13,14) which is formed in the inside of the housing; and rotary shafts(30) which include a rotor(40) which is arranged in the inside of the pump room and includes a thrust direction movement control member which allows the displacement generated by the thermal expansion of the thrust direction of the rotary shaft and the rotor in only one direction when the rotary vacuum pump runs and an elastic member which gives elastic supporting force to the opposite direction which the displacement direction is allowed by the thermal expansion of the rotary shaft. Absorption is proceeded while the gas within the pump room is transferred by the rotation of rotary shafts.

Description

Rotary Vacuum Pumps {ROTARY VACUUM PUMP}

This invention relates to the rotary vacuum pump which rotates a rotor by a rotating shaft, conveys gas in a pump chamber, and performs a suction effect.

Patent Document 1 discloses a multi-stage root pump, which is one of rotary vacuum pumps. The multi-stage root pump is formed so that two rotation shafts are arranged in parallel in the housing, and both ends are rotatably supported by a bearing. Each of the plurality of rotors provided in each of the rotating shafts has a configuration accommodated in the plurality of pump chambers arranged in a direction perpendicular to the rotating shaft in the housing.

Specifically, a plurality of rotors provided on one rotary shaft form a pair with each of the plurality of rotors provided on the other rotary shaft, and are accommodated in the respective pump chambers in an engaged state. Each pump chamber has a suction region and a discharge region, and the discharge region of one pump chamber is connected to the suction region of an adjacent pump chamber via a communication path. Moreover, the suction area of the pump chamber located at one end side is connected with the suction hole which communicates with the outside, and the discharge area of the pump chamber located at the other end side is connected with the discharge port which communicates with the outside.

One end of the rotary shaft is connected to a drive source, and a gear formed on the same rotary shaft meshes with a gear formed on the other rotary shaft, so that each rotary shaft rotates in the opposite direction in synchronization. Although not clearly described in Patent Literature 1, in the multi-stage root pump, the one and the other rotary shafts have a lock nut or a radial bearing at one end of the rotary shaft in order to define the position of the rotor in the pump chamber. And movement in the direction of the rotation axis by means such as press-fitting of the rotation shaft.

In the multistage rooted pump configured as described above, the other rotary shaft is also rotated by driving the one rotary shaft, and the pair of rotors accommodated in the respective pump chambers is rotated. The gas sucked into the pump chamber at one end via the suction port is conveyed by being sucked into the adjacent pump chamber in order while being compressed by the rotation of the pair of rotors. From the pump chamber of the other end side, the compressed gas is discharged | emitted to the exterior via the discharge port.

Patent Document 1: Japanese Unexamined Patent Publication No. 2008-51116

Since the multistage route pump configured as described above generates high heat during operation, particularly at the discharge port side, the housing, the rotor, and the rotating shaft are thermally expanded. In addition, when the multi-stage root pump is stopped, the housing, the rotor, and the rotating shaft are cooled by the air, and thus heat shrink. In operation, however, the housing is in direct contact with the atmosphere, and in a state in which the cooling effect is easily received, but the rotor and the rotating shaft are present in the housing and do not receive the cooling effect of the atmosphere. As a result, a difference in thermal expansion amount is generated between the housing, the rotor, and the rotating shaft, and the rotor and the rotating shaft are displaced larger than the housing. Thus, a large gap in the thrust direction occurs between the pump chamber wall surface that is part of the housing and the rotor wall surface.

On the other hand, in the gas drawn in the pump chamber, powder and the like are mixed, so that foreign matters due to deposition of powder or the like tends to occur in the large gap in the above-described thrust direction. When the multi-stage root pump is stopped and thermally contracted in the state in which foreign matters are deposited, the rotor and the rotating shaft cannot be returned to the initial set position due to the presence of foreign matters, and thus, the rotor and the rotating shaft are strongly pressed against the foreign matters. For this reason, when the multi-stage root pump is restarted, a large frictional resistance is generated between the rotor and the foreign matter, and there is a fear that restarting is impossible.

The present invention provides a rotary vacuum pump that can alleviate the frictional resistance upon restarting by foreign matter deposited in the pump chamber.

The present invention according to claim 1, wherein the pump chamber is formed in a housing, the rotor disposed in the pump chamber is provided with a plurality of rotation shafts, and the gas in the pump chamber is transported by rotation of the plurality of rotation shafts to perform a suction action. In the rotary vacuum pump, the rotary shaft includes thrust direction movement regulating means for allowing displacement in the thrust direction of the rotor and the rotary shaft generated in the operation of the rotary vacuum pump in only one direction, and the rotary shaft. And a first elastic member for imparting elastic support in a direction opposite to the direction in which the thermal expansion is allowed. According to this invention of Claim 1, even if the foreign material accumulates in the thrust direction polarity generate | occur | produced in the said pump chamber by the difference of the amount of thermal expansion between the said housing, the said rotor, and the said rotating shaft, during the operation of the said rotary vacuum pump, The friction force between the housing and the rotor accompanying the heat shrinkage at the time of stopping the rotary vacuum pump can be absorbed by the deformation of the first elastic member, so that the rotary vacuum pump can be restarted without any trouble.

The present invention according to claim 2 is provided with a second elastic member for imparting an elastic support force in a direction that allows the thermal expansion with respect to the rotation axis. In addition to being able to position by the elastic member, frictional resistance due to foreign matter deposited in the pump chamber by thermal expansion can be alleviated.

The present invention according to claim 3, wherein the thrust direction movement regulating means comprises a stepped portion formed on the rotary shaft and a bearing supporting the rotary shaft, and is directly or indirectly contacted with the stepped portion and the bearing. In order to be characterized in that the movement in the thrust direction is regulated, the object of the present invention can be achieved by simple means.

In this invention of Claim 4, since the said 1st elastic member is arrange | positioned between the said step part and the said bearing, Preferably, an elastic support force can be provided to a rotating shaft.

The present invention according to claim 5 is characterized in that the rotary vacuum pump is a multi-stage root pump, so that the present invention can be preferably performed.

In this invention of Claim 6, the direction in which the said 1st elastic member gives an elastic support force with respect to the said rotating shaft is the same as the conveying direction of the gas in the said multistage root pump, The said thrust direction movement restricting means is the said multistage type. In order to arrange | position to the last stage side of a root pump, the movement of a thrust direction can be regulated in the last stage side of the said multistage root pump, and the leak from the pump room of a final stage can be prevented effectively.

According to the present invention, the rotary vacuum pump can be smoothly restarted regardless of deposition of foreign matter in the pump chamber.

(1st embodiment)

EMBODIMENT OF THE INVENTION Hereinafter, 1st Embodiment which implemented this invention on the multistage root pump is described based on FIGS. In addition, in this specification, with respect to the direction of a multistage route pump, the left side of FIGS. 1-4 is front, the right side is rear, the upper side is upward, and the lower side is downward, and the right side of FIGS. 5 and 6 is front and left. It demonstrates as a back surface.

As for the housing 1 which forms the external form of a multistage root pump, the front housing 2, the rotor housing 3, the rear housing 4, and the gear housing 5 are joined in order from the front side, and the inside is sealed. In the state, it is integrated by a bolt (not shown) etc., for example. As outlined in FIGS. 5 and 6, the housings 2 to 5 each have a configuration in which a cylindrical body having an approximately elliptical inner space is divided into two upper and lower portions. This two-split configuration is effective for mounting a multi-stage root pump, and for example, is mounted so as to be integrated in a sealed state by covering an upper divided cylindrical body after attaching the members of the mechanisms described later to the lower divided cylindrical body. . In addition, since the two-part structure of each housing 2-5 is not closely related to this invention, detailed description is abbreviate | omitted. In addition, each structure of a multistage route pump is demonstrated based on the attached state like each figure.

Inside the rotor housing 3, partition walls 6 to 9 divided into two upper and lower parts are mounted to be narrowed in order from the front side so as to form an ellipse shape, and between the partition wall 6 and the front housing 2, respectively. Pump chambers 10 to 14 are formed between the partition walls 6 to 9 and between the partition wall 9 and the rear housing 4, respectively. Therefore, each partition wall 6-9 is comprised as a part of the rotor housing 3 for forming the pump chambers 10-14. Moreover, each pump chamber 10-14 has the volume reduced in order from the front side.

Each partition wall 6-9 has the communication space 15-18 inside. As shown in FIG. 1, each communication space 15-18 has the discharge passage 19-22 opened to the front side downward, and has the suction passage 23-26 opened to the rear side upward.

Each pump chamber 10-14 forms the intake area | region of gas in the upper space, and forms the discharge area | region of gas in the lower side in FIG. The pump chamber 10 communicates the suction region to the suction port 27 which connects to the outside formed above the rotor housing 3, and communicates the discharge region to the discharge passage 19 of the partition wall 6. Each of the pump chambers 11 to 13 formed between the partition walls 6 to 9 communicates the suction region with the suction passages 23 to 25 of the partition walls 6 to 8, respectively, and discharges the discharge region to each partition wall ( It communicates with the discharge passages 19-22 of 6-9. The pump chamber 14 communicates the suction region with the suction passage 26 of the partition wall 9, and the discharge passage communicates with the discharge port 28 connected to the outside formed below the rotor housing 3.

In the above configuration, the suction port 27 and the suction passages 23 to 26 each constitute a suction part of gas for each pump chamber 10 to 14, and the discharge passages 19 to 22 and the discharge port 28 are each pump chamber. The discharge part of the gas with respect to (10-14) is comprised.

Nearly the center of the housing 1, two rotary shafts 29 and 30 are arranged in parallel so as to penetrate from the front side to the rear side. The rotating shafts 29 and 30 are each provided with the plurality of rotors 31-40 of the cross shape (refer FIG. 5) integrated on the circumferential surface. The rotors 31 and 36 are engaged so as to be paired and accommodated so as to be rotatable in the pump chamber 10. Hereinafter, the rotors 32 and 39 are in the pump chamber 11, and the rotors 33 and 38 are pump chambers. 12, the rotors 34 and 39 are housed in the pump chamber 13 so that the rotors 35 and 40 can rotate in the pump chamber 14, respectively.

Front end portions of the rotary shafts 29 and 30 are supported by the front housing 2 so as to be rotatable by bearings 41 and 42, respectively. The bearings 41 and 42 can move in the thrust direction with respect to the front housing 2. Ring members 43 and 44 are fixed to the circumferential surfaces of the rotary shafts 29 and 30, and plate springs 45 and 46 as second elastic members are interposed between the ring members 43 and 44 and the front housing 2. It is. Accordingly, the rotary shafts 29 and 30 are configured to receive the elastic support force to the front side via the bearings 41 and 42 and the ring members 43 and 44 by the disc springs 45 and 46. Moreover, the sealing members 47 and 48 are attached between the outer peripheral surface of the ring members 43 and 44 and the inner peripheral surface of the front housing 2, and it is comprised so that the gas in the pump chamber 10 may not leak out. In addition, 65 is a cover which covers the front side edge part of the rotating shaft 29,30.

The rear side of the rotation shafts 29 and 30 is supported to be rotatable by the bearings 51 and 52, and the bearings 51 and 52 are supported by the holders 49 and 50 mounted on the inner circumferential surface of the rear housing 4. It is. In the rear position more than the bearings 51 and 52, the spring bearing rings 53 and 54 which are twisted and fixed to the main surface of the rotating shafts 29 and 30 are arrange | positioned. The spring bearing rings 53 and 54 are fixed to the rotation shafts 29 and 30 by appropriate means after the mounting position is adjusted, and the configuration is simple by using a double nut or the like.

Between the inner ring of the bearings 51 and 52 and the spring bearing rings 53 and 54, the coil springs 55 and 56 which are the 1st elastic members of this invention comprised as a compression spring are mounted, and are attached to the rotating shafts 29 and 30. The elastic support force to the rear side is provided. The rotary shafts 29 and 30 have a configuration in which movement in the thrust direction with respect to the bearings 51 and 52 is permitted. Preferably, since the spring force of the coil springs 55 and 56 is set strongly with respect to the disc springs 45 and 46, the rotation shafts 29 and 30 can take the state located in the most rear side.

In the space in the rear housing 4 located on the front side of the bearings 51, 52, labyrinth mechanisms 57, 58 are disposed on the rotation shafts 29, 30, and the pump chamber 14 and the bearing 51, 52) It seals between the spaces on the side. The rear end portions of the rotary shafts 29 and 30 protruding into the internal space of the gear housing 5 are provided with gears 59 and 60, respectively, and are rotationally transmitted by engagement of both gears 59 and 60. The rotary shaft 29 is connected by the motor shaft 61 and the joint 62 of the motor M fixed to the rear side outer end surface of the gear housing 5, and receives the driving force of the motor M. As shown in FIG.

The discharge port 28 communicated with the discharge area of the pump chamber 14 as the final stage is connected to the muffler 63 and the discharge mechanism 64, and the gas discharged from the pump chamber 14 is discharge mechanism 64. It is discharged to the exhaust gas processing device not shown through the.

The multistage root pump having the above configuration operates as follows. The rotating shaft 29 is rotated by the driving force of the motor M, and the rotating shaft 30 is rotated via the gears 59 and 60. The rotors 31 to 35 of the rotary shaft 29 and the rotors 36 to 40 of the rotary shaft 30 each rotate in the pump chambers 10 to 14 in a state of being engaged in pairs. The gas is sucked from the suction port 27 with the rotation of the rotary shafts 29 and 30.

The gas sucked into the suction region of the pump chamber 10 serving as the first stage from the suction port 27 is transferred to the discharge region by the rotors 31 and 36, and the discharge passage 19 of the partition wall 6, the communication space. The suction area of the pump chamber 11 of the second stage adjacent to the suction port 15 is sucked through the suction passage 23. The gas sucked into the pump chamber 11 is transferred to the discharge area by the rotors 32 and 37, and is discharged through the discharge passage 20, the communication space 16, and the suction passage 24 of the partition wall 7. It is attracted to the pump chamber 12 which becomes three steps. In the same manner below, the gas in the pump chamber 12 is sequentially transferred to the pump chamber 13 serving as the fourth stage and the pump chamber 14 serving as the final stage.

The gas sucked from the suction port 27 is sequentially compressed while being transferred from the pump chamber 10 to the pump chamber 14, and is discharged to the discharge port 28 as a gas of high temperature and high pressure. For this reason, the rotor housings 3 including the partition walls 6 to 9 and the rotation shafts 29 and 30 including the rotors 31 to 40 are thermally expanded to be displaced in the thrust direction and the radial direction. The attachment of the rotation shafts 29 and 30 to the rotor housing 3 and the rear housing 4 is configured to allow displacement in the thrust direction due to the thermal expansion. The rear side surfaces of the flange portions 29a and 30a formed to form the stepped portions on the rotary shafts 29 and 30 located in the rear housing 4 abut the front end surfaces of the labyrinth mechanisms 57 and 58. Therefore, the rotation shafts 29 and 30 are restricted to the rear side by the bearings 51 and 52 which are the support parts of one end side, and the flange parts 29a and 30a of the rotation shafts 29 and 30, the labyrinth mechanism 57, 58 and the bearings 51 and 52 constitute a thrust direction movement restricting means. The flange portions 29a and 30a of the rotation shafts 29 and 30 may be formed by circlips.

In addition, the multi-stage root pump fixes the housing 1 to a mounting pedestal not shown through the anti-vibration rubber (not shown), and the motor M is mounted in a state of being suspended in the rear end face of the housing 1. Because of the configuration, thermal expansion of the housing 1 is absorbed by the anti-vibration rubber.

The first embodiment configured as described above acts as follows.

The state of each part during operation | movement of a multistage route pump is demonstrated based on FIG. 3 and FIG. 4 which represented the rotors 36-40 of the rotating shaft 30 as a representative. The gas drawn into the pump chamber 10 of the first stage by the operation of the multistage route pump is conveyed while being sequentially compressed into the pump chamber 14 of the final stage. In the pump chamber 14, the gas which became hot by high compression is discharged. For this reason, the rotor housing 3 including the partition walls 6 to 9 and the rotation shaft 30 including the rotors 36 to 40 are thermally expanded in the radial direction and the thrust direction by thermal expansion.

< 회전축측 열팽창 β 의 관계가 생긴다.Among them, the thermal expansion in the thrust direction is displaced to the suction side of the gas to be the front side because only displacement in one direction is allowed (see arrow direction in FIG. 3). The displacement amount due to thermal expansion is the largest around the pump chamber 14. However, since the outer periphery of the rotor housing 3 is exposed to the outside air, the rotor housing 3 is in a state of receiving a constant cooling effect including the partition walls 6 to 9. On the other hand, the rotating shaft 30 separated from the rotor housing 3 and including the rotors 36 to 40 housed therein is not subjected to the cooling effect by the outside air. Therefore, as indicated by the length of the arrow in Fig. 3, the thermal expansion amount is the housing side thermal expansion.

<A relationship between the rotational axis-side thermal expansion β occurs.

In particular, a large gap 66 is generated between the front wall surface of the rear housing 4 constituting the pump chamber 14 and the rear wall surface of the rotor 40. The powder etc. mixed in the gas conveyed to the pump chambers 10-14 are easy to accumulate especially in the big gap 66, and the foreign material 67 (refer FIG. 4) agglomerates here. Since the gap 66 is large during operation of the multistage root pump, there is no problem in particular. However, when the multi-stage route pump stops, the heating source by the hot gas disappears, so that the whole is rapidly cooled.

4 shows the stop of the multi-stage root pump. The rotor housing 3 including the partition walls 6 to 9 and the rotation shaft 30 including the rotors 36 to 40 are displaced to the rear side so as to return to the initial setting position by thermal contraction. The rotational shaft 30 including the rotors 36 to 40 having a large thermal expansion amount also has a large amount of thermal contraction, and as shown by the length of the arrow in FIG. 4, a relationship between the housing-side thermal contraction γ and the rotational shaft-side thermal contraction δ occurs. However, foreign matter 67 deposited during operation is present in the gap 66 of the pump chamber 14.

When the rotor 40 tries to return to the initial setting position, the foreign matter 67 is caused by the spring force of the coil spring 56 between the rotor 40 and the front side wall surface of the rear housing 4 in the pump chamber 14. Is fitted on. The foreign matter 67 becomes a large rotational resistance with respect to the rotor 40. In this embodiment, the rotation shaft 30 is kept slightly displaced to the front side by the extension of the coil spring 56. For this reason, the engagement by the foreign material 67 being strongly pressed between the rotor 40 and the front side wall surface of the rear housing 4 by the heat shrink of the rotor 40 is prevented. Moreover, even if foreign matter 67 is deposited between any of the poles of the pump chambers 10 to 14, the front side wall surfaces, partition walls 6 to 9 and front housing 2 of the rotors 36 to 40 and the rear housing 4 are provided. The foreign matter 67 is prevented from being engaged between the rear side wall surfaces of the.

When the multistage route pump is instructed thereafter, the pressing force of the rotor 40 against the foreign matter 67 is small, and the frictional resistance is small, so that it starts smoothly. In addition, the foreign matter 67 is expected to be gradually removed by the pressure of the gas or the rotation of the rotor 40 during the restarting of the multistage route pump. Even if the foreign matter 67 remains deposited, the rotor 40 is not strongly pressed against the foreign matter 67 by the extension of the coil spring 56, so that the multistage root pump does not interfere with operation. .

The first embodiment described above has the following effects.

(1) Generation of large frictional resistance due to deposition of foreign matter 67 by a simple configuration in which the coil springs 55 and 56 are elastically supported and the rotational shafts 29 and 30 can be displaced in the rotational axis direction. Can be suppressed.

(2) By interposing the disc springs 45 and 46 and the coil springs 55 and 56 on the front side and the rear side of the housing 1, respectively, of the rotors 36 to 40 in the pump chambers 10 to 14. Positioning of an initial setting position can be performed easily.

(3) The direction in which the coil springs 55 and 56 impart an elastic bearing force to the rotary shafts 29 and 30 is the same as the gas feeding direction in the multistage root pump, and the flange portion of the rotary shafts 29 and 30 ( 29a, 30a, labyrinth mechanisms 57, 58, and bearings 51, 52 restrict the movement in the thrust direction on the final stage side of the multi-stage root pump, effectively preventing leakage from the pump chamber 14 of the final stage. can do.

This invention is not limited to the structure of embodiment mentioned above, Various changes are possible within the meaning of this invention, and it can carry out as follows.

(1) The first elastic member of the present invention is not limited to the coil springs 55 and 56, and an elastic member such as a disc spring or a resin or rubber can be used.

(2) The first elastic members such as the coil springs 55 and 56 are not limited to the rear side, and may be disposed at the intermediate position between the front side or the rear side and the front side.

(3) The first elastic member represented by the coil springs 55 and 56 is not limited to the configuration formed on the rotation shafts 29 and 30 as in the first embodiment, and the rotation shafts 29 and 30 are rotated along the rotation axis. If it is the structure which can be elastically supported in the direction, you may arrange | position and form in another position. In addition, in description of each following embodiment, the number in parentheses shows the structural member of the rotating shaft 30 side shown in FIG. For example, the 2nd Embodiment shown in FIG. 7 is comprised so that the bearing 51 (52) may slide integrally with the rotating shaft 29 (30), and the outer ring of the bearing 51 (52). Abuts against the regulating plate 68 (69) attached to the holder 49 (50). Thus, the rotational shafts 29 and 30 and the bearings 51 and 52 are restricted from moving to the rear side (right side in FIG. 7), but are allowed to move to the front side (left side in FIG. 7) by thermal expansion. . The coil spring 70 (71) which is the 1st elastic member of this invention is arrange | positioned between the protrusion part 72 (73) formed in the front side of the holder 49 (50), and the outer ring of the bearing 51 (52). Formed. The coil spring 70 (71) elastically supports the rotating shaft 29 (30) and the bearing 51 (52) in a direction opposite to the direction in which it is moved by thermal expansion (right side in Fig. 7). The second embodiment can expect the same effects as the first embodiment.

(4) The 3rd Embodiment shown in FIG. 8 is comprised so that the bearing 51 (52) and the holder 49 (50) may slide together with the rotating shaft 29 (30) integrally. As for the bearing 51 (52), the holder 49 (50), and the rotating shaft 29 (30), the flange part 29a, 30a of the rotating shaft 29 (30) shown in FIG. 1 and FIG. 2 has a labyrinth mechanism. By contacting with 57 and 58, movement to the rear side (right side of FIG. 8) is regulated, and movement to the front side (left side of FIG. 8) by thermal expansion is permitted. The coil spring 74 (75), which is the first elastic member of the present invention, has a rear side projection 76 (77) of the holder 49 (50) and a rear side cutout 78 (79) of the rear housing 4. It is arranged in between. The coil spring 74 (75) is in a direction opposite to the direction in which the rotating shaft 29 (30), the bearing 51 (52) and the holder 49 (50) are moved by thermal expansion (right side in FIG. 8). Elastic support. The third embodiment can expect the same effects as the first embodiment.

(5) Instead of the disc springs 45 and 46 which are the second elastic members, rigid regulation which can regulate the movement of the rotating shafts 29 and 30 to the rear side by the coil springs 55 and 56 is carried out. Even if the member is disposed, the effect of the present invention can be obtained.

(6) The displacement direction of the rotor housing 3 including the partition walls 6 to 9 by thermal expansion and the rotation shafts 29 and 30 including the rotors 31 to 40 has the same suction side side as in the first embodiment. It is not limited to this, You may comprise so that it may displace only to the discharge part side.

(7) The housing 1 does not necessarily have to be a two-part structure, but can also be set as a one-piece | unit or three or more divisions.

(8) The present invention is not limited to a multistage root pump, but can also be applied to a root pump having one pump chamber.

(9) This invention is not limited to a root pump, For example, it can carry out by the rotary vacuum pump using a screw pump, a gear pump, etc.

1 is a front sectional view of a multistage root pump.

2 is a plan sectional view of a multi-stage root pump.

3 is a planar cross-sectional view of a part showing the time of thermal expansion.

4 is a planar cross-sectional view of a part showing the time of thermal contraction.

5 is a cross-sectional view taken along the line A-A of FIG.

6 is a cross-sectional view taken along the line B-B in FIG.

7 is a partial sectional view showing a second embodiment.

8 is a partial cross-sectional view showing the third embodiment.

* Description of the symbols for the main parts of the drawings *

1: housing

2: front housing

3: rotor housing

4: rear housing

5: gear housing

6-9: partition wall

10 to 14: pump room

15 to 18: communication space

19 to 22: discharge passage

23 to 26: suction passage

27: inlet

28: discharge port

29, 30: axis of rotation

31 to 40: rotor

41, 42, 51, 52: bearing

45, 46: plate spring

53, 54: spring bearing ring

55, 56, 70, 71, 74, 75: coil spring

64: discharge mechanism

66: interstitial

67: foreign matter

72, 73, 76, 77: protrusion

78, 79: cutout

M: motor

Claims (6)

A rotary vacuum pump which forms a pump chamber in a housing, includes a rotor disposed in the pump chamber in a plurality of rotation shafts, and transfers gas in the pump chamber by rotation of the plurality of rotation shafts to perform a suction action. The rotating shaft includes thrust direction movement regulating means for allowing displacement in the thrust direction of the rotor and the rotating shaft generated in the operation of the rotary vacuum pump in only one direction, and the thermal expansion with respect to the rotating shaft. And a first elastic member for imparting elastic support in a direction opposite to the direction. The method of claim 1, A rotary vacuum pump, comprising: a second elastic member for imparting elastic support force in a direction that allows the thermal expansion with respect to the rotary shaft. The method according to claim 1 or 2, The thrust direction movement restricting means comprises a stepped portion formed on the rotary shaft and a bearing supporting the rotary shaft, and the movement in the thrust direction is restricted by direct or indirect contact between the stepped portion and the bearing. Rotary vacuum pump. The method of claim 3, wherein The said 1st elastic member is arrange | positioned between the said step part and the said bearing, The rotary vacuum pump characterized by the above-mentioned. The method of claim 1, The rotary vacuum pump is a rotary vacuum pump, characterized in that the multi-stage root pump. The method of claim 5, The direction in which the first elastic member imparts elastic support force to the rotating shaft is the same as the conveying direction of the gas in the multistage root pump, and the thrust direction movement restricting means is disposed on the last end side of the multistage root pump. Rotary vacuum pump, characterized in that.

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