JPH056195U - Vacuum pump - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the gas and water sucked from the suction port of the vacuum pump from leaking into the rotor, and to improve the exhaust efficiency. [Structure] Base 17 facing lower end surface 4a of rotor 4
The auxiliary screw groove 18 is formed on the upper end surface 17a of the rotor 4. When the rotor 4 rotates at high speed, the auxiliary screw groove 18 performs a pumping action by the relative movement of the rotor lower end surface 4a and the base upper end surface 17a, and the auxiliary screw groove 18 Inhaled gas and water are
It is discharged from the discharge port portion 3 through the exhaust passage 16 without leaking inside the rotor 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vacuum pump that evacuates a vacuum chamber or the like.

[0002]

[Prior Art]

 Conventionally, when manufacturing IC products, for example, each process is performed in each work chamber, and when one process is completed in one work chamber, the work is transferred to the next work chamber via the gate valve. ing. Here, in one working room, it may be necessary to evacuate this room, and in this case a vacuum pump was used.

As such a vacuum pump, for example, there is a composite turbo-molecular pump as shown in FIG. In the figure, reference numeral 101 is a casing, and a suction port portion 102 and a discharge port portion 103 are formed in the casing 101, and a rotor 104 is housed in the casing 101. A rotor blade 105 and a spiral screw groove 108 are formed toward the peripheral wall surface, and the stator blade 106 and the stator 109 are attached to the inner peripheral wall surface of the casing 101 so as to face the rotor blade 105 and the screw groove 108. .. The rotor 104 is rotated by a motor 107 housed in the casing 101, and the rotor blades 105 rotate at a high speed relative to the stator blades 106.

When the rotor 104 is rotationally driven by the motor 107, the rotor blades 105 rotate at a relatively high speed with respect to the stator blades 106. The rotor blades 105 and the thread grooves 108, the stator blades 106, and the stator In cooperation with 109, molecules such as gas and water in the work chamber 109 are sucked in through the suction port 102. The sucked molecules pass between the stator 109 and the rotor 104, further pass through the exhaust passage 111 in the base 110 fixed to the status 109, and are discharged from the discharge port 103.

A rotor shaft 112 is fixed to the rotor 104, and an axial electromagnet 113 is provided on the rotor shaft 112. When the rotor shaft 112 is rotated by the motor 107, the rotor 104 rotates at a relatively high speed with respect to the base 110. At this time, the rotating rotor 104 is levitated by the axial electromagnet 113 so as to rotate smoothly without coming into contact with the base 110 fixed to the stator 109.

[0006]

[Problems to be solved by the device]

 However, in such a conventional turbo molecular pump, the rotor 104 is levitated by the electromagnetic magnet 113 in the axial direction so as not to contact the stationary base 110 during this rotation. Therefore, the gap between the lower end surface 104a of the rotor 104 and the upper end surface 110a of the base 110 is larger than that of the ball bearing type. Therefore, molecules such as gas and water sucked from the suction port 102 by the rotor blades 105 and the screw grooves 108 and the stator blades 105 and 109 are shown in solid lines in FIG. Between the lower end surface 104a and the upper end surface 110a, and at the same time, the gas is exhausted through the exhaust passage 111 in the base 110. Therefore, there is a problem in that gas such as gas and water molecules sucked from the suction port 102 leak into the rotor 104, so that exhaust efficiency is reduced.

[0007]

[Means for Solving the Problems]

 In order to solve such a problem, according to the present invention, a rotor arranged to face a stator and a rotor interposed between the rotor and the stator rotate relative to the stator. Then, in a vacuum pump including a suction part for sucking gas and the like and a base rotatably supporting the rotor, the gas is supplied to at least one of the facing surfaces of the rotor and the base. The structure is such that a suction auxiliary section for sucking is provided together with the suction section.

[0008]

[Operation] When the pump is operating, the rotor is levitated from the base by the axial electromagnet, and the rotor rotates smoothly with respect to the base. Therefore, there is a large gap between the lower end surface of the rotor and the upper end surface of the base. Molecules such as gas and moisture passing through the suction portion are likely to flow out and leak into the rotor from between the lower end surface and the upper end surface. However, a suction assisting portion is formed on the opposing surface of the rotor or the base. Therefore, when the rotor rotates at high speed, molecules such as gas and water flowing to the suction section are forcibly discharged into the exhaust passage by the suction auxiliary section and do not flow into the rotor and leak.

[0009]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. 1 to 3 are views showing an embodiment of a vacuum pump according to the present invention. First, the configuration will be described. In the figure, reference numeral 1 is a casing of a composite turbo-molecular pump, the casing 1 has a substantially cylindrical shape as a whole, and a working chamber (not shown) as a vacuum chamber is provided above the casing 1. 2) is formed with a suction opening 2 and a discharge opening 3 below. A rotor 4 is housed in the casing 1 in the direction of the center line, and a plurality of rotor blades 5 are formed in the upper half portion of the rotor 4 in FIG. 1 toward the inner wall surface of the casing 1. The rotor blades 5 are formed in multiple stages in the axial direction of the rotor 4. A plurality of similarly formed stator blades 6 are arranged so as to face the rotor blades 5, are located between the multi-stage rotor blades 5 and are attached to substantially the upper half of the casing 1. Further, a spiral main screw groove 14 is formed on the outer peripheral wall of the lower half of the rotor 4, and a substantially cylindrical stator 15 facing the main screw groove 14 is disposed below the inner peripheral wall of the casing 1. It is installed in half. The rotor blades 5 and the main screw grooves 14, and the stator blades 6 and the stator 15 together constitute a suction portion. When the rotor blade 5 and the main screw groove 14 rotate at a relatively high speed with respect to the stationary stator blade 6 and the stator 15, molecules such as gas and water in the working chamber are forcibly sucked from the suction port 2. It is discharged from the discharge port 3.

On the other hand, a cylindrical fixed cylinder 7 is provided inside the rotor 4, and a rotor shaft 8 is arranged at the axial portion of the fixed cylinder 7 so as to rotate integrally with the rotor 4. There is. Inside the fixed cylinder 7, a motor 9 for rotationally driving the rotor shaft 8 to rotate the rotor blade 5 and the main screw groove 14 with respect to the stator blade 6 and the stator 15, and a magnetic suspension of the rotor shaft 8 in the radial direction. A radial electromagnet 10 is rotatably supported without contact, and an axial electromagnet 11 is magnetically levitated in the axial direction to rotatably support the rotor shaft 8 without contact.

A base 17 in which an exhaust passage 16 is formed is interposed between the lower outer wall portion of the fixed cylinder 7 in FIG. 1 and the lower portion of the stator 15, and the base 17 is located above the base 17 and faces the upper end surface 17 a. The lower end surface 4a of the rotor 4 is located. When the rotor 4 is rotated, the rotor 4 is levitated further upward from the base 17 by the axial electromagnet 11 so as to rotate smoothly. At this time, as shown in FIG. 2, molecules such as gas and water sucked between the main screw groove 14 and the stator 15 are discharged from the discharge port portion 3 through the exhaust passage 16 formed in the base 17. To be done.

Further, as shown in FIG. 3, the upper end surface 17 a of the base 17 facing the lower end surface 4 a of the rotor 4 has an auxiliary screw groove 18 (suction) which is shaped so as to turn to the center of the base 17 and converge. The auxiliary screw groove 18 is formed in the same annular shape as the lower end surface 4a of the rotor 4 as a whole. Further, the exhaust passage 16 is opened at the upper end surface 17a of the base 17. Protective dry bearings 20 and 21 are provided around the upper and lower ends of the rotor shaft 8 in the figure.

Next, the operation will be described. When it is necessary to evacuate the work room according to the work content, the work room is evacuated by the combined turbo molecular pump. For that purpose, first, the motor 9 is started to rotationally drive the rotor 4, and the rotor blade 5 and the main screw groove 14 are rotated at a relatively high speed with respect to the stationary stator blade 6 and the stator 15. As described above, when the rotor blade 5 and the main screw groove 14 rotate relative to the stator blade 6 and the stator 15, molecules such as gas and moisture in the working chamber are forcibly sucked from the suction port 2 and the stator 15 and It is removed from the discharge port 3 through the exhaust passage 16 from between the main screw grooves 14.

Here, the rotor 4 is levitated from the base 17 by the axial electromagnet 9, and the rotor 4 smoothly rotates in the clockwise direction with respect to the base 17 in FIG. A large gap is formed between the lower end surface 4a of the rotor 4 and the upper end surface 17a of the base 17 by the rollers. Therefore, as shown in FIG. 2, molecules such as gas and moisture passing through the stator 15 and the main screw groove 14 flow out into the rotor 4 between the lower end surface 4a and the upper end surface 17a as shown by a broken line and leak. It will be. However, an auxiliary screw groove 18 is formed on the upper end surface 17a of the base 17. Therefore, when the rotor 4 rotates in the clockwise direction at a high speed relative to the auxiliary screw groove 18, the molecules of gas, moisture, etc. flowing between the stator 15 and the main screw groove 14 are, as described above, changed. It flows into the rotor 4 and is forcibly discharged into the exhaust passage 16 as shown by the solid line without leaking. Therefore, molecules such as gas and water sucked from the suction port 2 are prevented from leaking into the rotor 4 and are forcibly discharged. As a result, molecules such as gas and water sucked from the suction port are prevented from leaking into the rotor, and the exhaust efficiency is improved.

Although the auxiliary screw groove 18 is formed on the upper end surface 17a of the base 17 in this embodiment, the auxiliary screw groove 18 may be formed only on the lower end surface 4a of the rotor 4. May be formed on both the upper end surface 17a and the lower end surface 4a. Further, the suction assist portion is not limited to the auxiliary screw groove 18, but may be a rotor blade or a stator blade. Even in this case, the same effect as in the above embodiment can be obtained.

On the other hand, the suction part may be a turbo molecular pump composed only of a rotor blade and a stator blade, or may be a thread groove type vacuum pump composed only of a stator and a screw groove.

[0017]

[Effect of the device]

 As described above, according to the present invention, since the suction assisting portion for sucking gas or the like together with the suction portion is provided on at least one of the facing surfaces of the rotor and the base, the suction assisting portion is provided. Molecules such as gas and water that have been sucked in by the unit and flowed are forcibly discharged to the exhaust passage of the base. Therefore, molecules such as gas and moisture sucked from the suction inlet are prevented from leaking into the rotor and are forcibly discharged, so that the exhaust efficiency is improved.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a vacuum pump according to the present invention.

FIG. 2 is an enlarged view of a II portion in FIG.

FIG. 3 is a plan view of an upper end surface of a base.

FIG. 4 is an overall sectional view of a conventional vacuum pump.

5 is an enlarged view of a V portion in FIG.

[Explanation of symbols]

 4 rotor 5 rotor blade 6 stator blade 14 main screw groove 15 stator 17 base 18 auxiliary screw groove

Claims (1)

Claims for utility model registration: Claims: 1. A rotor arranged to face a stator, and a gas interposed between the rotor and the stator when the rotor rotates relative to the stator. In a vacuum pump having a suction part for supporting the rotor and a base rotatably supporting the rotor, at least one of respective surfaces of the rotor and the base facing each other, for sucking gas together with the suction part. A vacuum pump characterized by having a suction assist section.