JPH02503703A - turbo molecular vacuum pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] turbo molecular vacuum pump Technical field The present invention is a gas displacement rotary pump. mp), more specifically, high vacuum with an axial flow of gas. ), i.e. turbomolecular vacuum pumps (turbomolee ular vacuum pumps).

Background of the invention Modern developments in science and engineering have led to various evacuating characteristics, especially port pump pumping speed (pu+eping 5peed) and gas compression degree (gas Many types of turbos with different compression degrees Requires a molecular pump.

This turbomolecular vacuum pump is equipped with a hollow stator, whose axial hole is , rigidly connected to the shaft and housing a hollow rotor rotated by the shaft. turbo Molecular and molecular gas-evacuation stage The passageway on the floor is where the rotor and stator are facing each other. (counteropposed) planes.

In the molecular gas discharge step, the pressure of the gas discharged on the compression side is increased to 100 Pa. Also, the increase in pressure of the gas relative to atmospheric level is due to the presence of turbomolecular vacuum pumps. In previous designs, a separate auxiliary vacuum pump connected to the turbomolecular vacuum pump Requires equipment for an auxiliary vacuum gas evacuation stage. However, this In the design, the hydrocarbon molecules are transferred from the internal space of the auxiliary vacuum pump to the engineering chamber ( Bringing the cleanliness of a vacuum to the exhaust space of a technological chamber decreases and, in long-term cases, reduces the quality of the expelled product, but Move through the gas exhaust passage. The transfer of hydrocarbons can be achieved, for example, by turbomolecular vacuum points. Nitrogen traps make pump purification more complicated and expensive.

The action of the auxiliary vacuum gas evacuation stage is a dynamic seal (dynamic 5eal). Vacuum pumps operated in this way are likewise known in the prior art. this luck The passageway of the dynamic seal is a turbomolecular vacuum pump, one element of which begins to rotate. are arranged between two cylindrical surfaces of a plurality of elements. Gap between the surfaces (g ap) customarily varies from 0.015 to 0.03 am. This exercise shirt The path of the roll is usually a multiple-start rectangular by grooves made on the surface of the rotating element in the form of ectangular threads. is formed. The depth of this wave is from 0.1 to 0.1 from the gas suction side to the gas compression side. It gradually decreases to 0.03 mm. The width of 711 is between two adjacent banks. is equal to the rib width of uired gas-evacuating characteristics ), determined by commonly used calculations.

The hollow stator has a hollow rotor inside, and the passage of the turbomolecular gas exhaust stage is disposed between the stator and the rotor, and is connected to a passageway in the molecular gas discharge stage. The latter communicates with the passage of the dynamic seal, said passage being connected to the atmosphere. A bearing that is open in the hollow rotor, is housed in the hollow rotor, and supports one end of the rotor shaft. Due to the inner surface of the The off-axis turbomolecular vacuum pump in the form of a rectangular hemlock is known in the prior art. (FRB 2224009).

The length of said portion of the shaft outer surface with the dynamic sealing edge may be output characteristics, especially gas compression value (gas co*pres-sion value). If ensured, it should be at least the diameter of the shaft. However, this increases the equatorial moment of inertia of the rotating shaft with the cantilever load of the bearing and the rotor. However, the shaft speed and the resulting discharge characteristics of the turbomolecular vacuum pump, In particular, it increases the degree of gas compression and the length of the shaft which limits the pumping speed of the pump.

However, the above-mentioned speed is It depends on the axis speed.

Summary of the invention The main object of the invention is to provide a turbomolecular vacuum pump without increasing its dimensions. Turbo minutes with such dynamic seals that ensure to increase the emission characteristics It is to provide a child vacuum pump.

The main object of the present invention is to provide molecular gas between the hollow stators of turbomolecular vacuum pumps. Turbomolecular gas discharge stage N communicating with the passage of the discharge stage lar gas-evacuatinFistage) passage is arranged. , a bearing that supports one end of the rotor shaft is installed inside the hollow rotor. The passage in the child gas placement stage communicates with the atmosphere through the passage in the dynamic seal; The shape of the multi-lead rectangular thread on the outer surface of the bearing is slightly oriented toward the inner surface of the rotor. is formed by a groove provided on the inner surface of the rotor; The section is provided on the outer surface of the rotor shaft in the form of a multi-lead rectangular thread, and its depth is gradually decreased from the gas suction side to the gas compression side and towards the said part. This is achieved by forming the inner surface of the bearing.

The dynamic seal provided on the outer surface of the rotor shaft and the inner surface of the rotor. Turbomolecular vacuum pump having oppositely oriented threads forming a passageway In this course, the depth of the grooves on the inner surface of the rotor gradually decreases from the gas compression side to the gas suction side. It is appropriate to be little.

A dynamic seal provided on the outer surface of the rotor shaft and the inner surface of the rotor. The groove of the turbomolecular vacuum pump also has threads in the same direction. In this case, the depth of the inner surface of the rotor gradually decreases from the gas suction side to the gas compression side. It is also practical.

its diameter is at least twice as large as the diameter of the shaft with the passage groove of the main dynamic seal; A supplementary dynamic seal formed by a groove on the inner surface of the cylindrical rotor. The passage equipment is the main movement seat, which in turn improves the discharge characteristics of the turbomolecular vacuum pump. clear passage area ) increases the unobstructed passage area of the supplementary athletic seal passage. There is a possibility that

Besides this, it has the main effect of reducing the equatorial moment of inertia of the axis with the rotor. It is possible to reduce the length of the dynamic seal, i.e. the length of the shaft, and Turbomolecular vacuum pump speed without changing its dimensions for data speed could increase by at least 20%.

Brief description of the drawing The invention will be explained in detail by describing specific embodiments thereof. .

FIG. 1 is an overall view (longitudinal sectional view) of the turbomolecular vacuum pump of the present invention.

Figure 2 shows that the helical thread forms the passageway of the main dynamic seal. They are facing towards the direction of Mt. Forms a supplementary athletic sticker The structural unit of FIG. 1 having grooves shown in FIG. 1 will now be described on an enlarged scale in accordance with the present invention.

Figure 3 - The direction of the helical thread forms the main dynamic seal passage. The webbing forms a passage for the complementary kinematic seal that matches the direction of the helical thread on the webbing. Same as in Figure 2.

BEST MODE FOR CARRYING OUT THE INVENTION The turbomolecular vacuum pump consists of a hollow stator 1 (first 1), and between the stator and rotor, there is a turbo molecule discharge stage. A passage 3 and a passage 4 for the molecular gas discharge stage are provided, and the passages communicate with each other. ing.

The stator 1 comprises turbo molecules that are rigidly connected to each other, for example by threaded joints. It includes a casing 5 for the gas exhaust stage and a casing 6 for the molecular gas exhaust stage.

Located between four blade wheels 9 that are firmly connected to the rotor 2. The hub 7 having three blade discs 8 placed thereon is - The true wheel and the true circular plate are provided in the casing 5 at the molecular gas discharge stage. In between there is a passage 3 of the turbomolecular gas evacuation stage.

The number of true wheels 9 and the corresponding true circular plates 8 is different from that of other known turbo molecular vacuum pumps. It can be varied as seen in the design of. This number is known can range from 2 to 20 and more, such as depending on the geometrical parameters of the structural elements, for example through the passage of the wing of the true wheel 9 , depends on the unobstructed passage area and the required gas exhaust of the turbomolecular vacuum pump. Depends on output characteristics.

The passage 4 in the molecular gas discharge stage has a multi-spiral rectangular thread. rt helicil rectangular thread) shaped stem A plurality of slots 11 in the cylindrical inner surface 10 of the casing 6 of the rotor 1 and the cylinder of the rotor 2 It is formed by the outer surface 12. The depth of the slot 11 is on the gas suction side V (Fig. from the gas compression side N (indicated by an arrow in the drawing) to the gas compression side N (indicated by an arrow in the drawing) ), it gradually decreases from 3.0 ms to 0.5-1. rotor The gap 13 between the cylindrical outer surface 12 of the stator 2 and the cylindrical inner surface 10 of the casing 6 of the stator 1 is , as is known, ranges from 0.15 to 0.03+ue and is sufficiently small. and provides a relatively high resistance to gas backflow, i.e. from the gas compression side N. Prevents gas from flowing toward the gas suction side■.

The rotor 2 is mounted on the shaft 14 and fixed thereto by screws 15. Ru. The shaft 14 has aerostatic bearings. ) System for supplying and distributing compressed air to 16 and 17 annular recesses 18 and 19 respectively communicating with passages (not shown in the drawings) of the It is mounted on two aerostatic bearings 16 and 17.

The bearings 16,17 are attached to the housing 20.

The step bearing 21 attached to the sleeve 22 together with the ring (riB) 23 is It is rigidly connected to the housing 20, for example by a threaded joint.

The sleeve 22 has a rotor 25 attached to the lower end 26 of the shaft 14. It houses the stator 24 of the motive force. A housing 27 is fixed to the sleeve 22. ing. To cool the turbomolecular vacuum pump, the housing 27 is connected to the ring 28 and 29 and shutter 30. Chain rings 28 and 29 are chain rings 28 and 29. and a retainer installed between the sleeve 29 and the sleeve 22 It is fixed by 31. The casing 6 of the stator 1 has an auxiliary vacuum of gas Conduits for forevauum evacuation (as shown in the drawing) has a hole 32 in which the pipe connection 33 is coaxially fixed in order to communicate with and pre-evacuation of gas from a sealed chamber (not shown in the drawings). eView-ation).

Due to the vacuum maintained in the chamber, the exhausted gas is separated by the pressure of the exhausted gas. A dynamic seal that increases the pressure at the outlet of passage 4 in the child gas discharge stage to atmospheric pressure. By providing a turbomolecular vacuum pump, it can be discharged directly to the atmosphere. Applicable The dynamic seal includes a portion 35 of the outer surface of the shaft 14 and an inner portion of the bearing 16 facing the portion 35. A main passageway 34 is provided between the surfaces.

The main passage 34 of the dynamic seal is located between the upper end surface of the bearing 16 and the shaft of the rotor on the gas suction side. Through the gap 38 between the receiver 16 and the opposite surface of the rotor, a portion of the inner surface of the rotor 2 37 and a dynamic seat located between the outer surface of the bearing 16 opposite the portion 37. It communicates with an additional passageway 36 of the tile.

The main passage 34 of the dynamic seal is located on the gas pressure side N in the radial direction provided in the bearing 16. through the passage and the longitudinal passage 39.40 and through the gap 41 between the shaft 14 and the bushing 42. and radial coaxial passages 43 and 43 formed in the bushing 2 and the casing 20, respectively. and 44 to the atmosphere.

The additional passage 36 of the dynamic seal is located between the inner surface of the rotor 2 and the bearing 16 and the casing 2. 0 through the gap 45, 46 between the outer surfaces of the stator 1 and the inner surface of the casing 6 of the stator 1. 10 and the outer surface of the casing 20 for the passage of the molecular gas evacuation stage through the annular space 47. It leads to Route 4.

The main passage 34 of the dynamic seal is a multi-start rectangular spiral. A plurality of grooves 48 (second ．． Figure 3).

The depth p of the plurality of grooves 48 varies from 0.1-1 to 0 from the gas suction side (■) to the gas pressure side (m). ．． It is gradually decreasing to 03 wa-.

Number of threads (nus+ber of 5 tarts) and part 35 (No. 2.3) The length (FIG. 2) or Ll (FIG. 3) depends on the diameter of the shaft 14. Groove 4 The width of 8 is the same throughout the length of section 35, while the ridges between adjacent ridges 48 The width a of the (rib) 49 is equal to the width of the arm 48.

The additional passage 36 of the dynamic seal is formed on the outer surface of the rotor 2 in the form of a multi-start rectangular thread. A plurality of arms 50 (Fig. 2) or a plurality of 211 made in the part 37 (Fig. 2.3) of 51 (FIG. 3). The length 11 of the arm 50.51 is for exercise. so as to ensure a differential pressure of the gas at the inlet and outlet of the passages 36 and 34 of the seal. Gradually along length H (Fig. 2) or length H (Fig. 3) of part 3 f (Fig. 2.3) is changing. The varying length of the groove 50.51! The direction of , is the screw of 71148. Depends on the direction of the spiral thread.

Additional passages in the dynamic seal to increase pump pumping speed and degree of gas compression The direction of the thread of the thread 50 (FIG. 2) forming the 36 is the main passage 34 of the dynamic seal. This is opposite to the direction of the threads of 71148 forming. Depth 11 of 50 is gas pressure It gradually decreases from 0.1 mm to 0.2 mm from the contraction side to the gas suction side. Ru.

The width of said beam 50 is the same throughout its length, and the width of the adjacent beam is equal to 2 mm. The width of the ridge 52 between the grooves 50 is equal to the width of the groove 5o, The length of the surface portion 35 is approximately equal to 0.3 to 0.5 of the diameter of the shaft 14, while The length H of the inner surface portion 37 of the rotor 2 is approximately 273 mm. L and H values and them The relationship depends on the required emission characteristics and is determined by commonly known calculations. be done. The value of L is always smaller than the diameter of the shaft 14, and the value of H is always smaller than L. This is smaller than the equatorial moment of inertia of the shaft 14 due to the rotor 16. real mo-meot of 1 intertia).

into an annular space 47 (Fig. 1) leading to an auxiliary vacuum line (not shown in the drawings). Turbomolecular vacuum pumps in case of an accidental increase in pressure up to the level of atmospheric pressure at In order to maintain the serviceability of the athletic seal, The main passage B36 of the dynamic seal is formed in the channel 51 (Fig. 3) that forms the additional passage 36. The screw threads are provided in a direction that corresponds to the direction of the threads of the arm 48. Wei 51 The depth 11 is 0.1 vs. 0.2 from the gas suction side V to the gas compression side N. It is gradually decreasing until am. The width of the ridge 51 and the width of the ridge 53 are exactly as shown in Figure 2. The length Ll of the portion 35 of the outer surface of the shaft 14, which as in the variant shown is equal to 2-ts, is equal to 0.5 to 0.8 of the diameter of the shaft 14, while the length of the inner surface 37 of the rotor 2 The length H is equal to 1/2 to 2/3 of Ll.

The selection of the exact values of Ll and Hl and their relationship also determines the required turbomolecular vacuum. It depends on the evacuation characteristics of the pump and is determined by calculations known to -a.

The turbo molecular vacuum pump works as follows.The pump is installed inside the stator 1 gate. 5 (Fig. 1) is located in a closed room of the corresponding technical equipment (as shown in the drawing). (I have not done so). The pipe connection 33 is connected to a pipe for auxiliary vacuum evacuation of the gas. (not shown in the drawings). Preliminary exhaustion of gas from a sealed room The auxiliary vacuum gas exhaust line is then evacuated by a valve (not shown in the drawing). ) is closed by the recess 9 and then compressed air under a pressure of 0.598 Pa enters the recess 18. and 19 into the gap between the shaft 14 and the aerostatic bearings 16 and 17 and the shaft 14 is "floating" within the aerostatic bearings 16 and 1. g) Start J.

Voltage is then supplied to the stator 24 of the motor and the rotor 25 of the motor is 2 and the shaft 14 is rotated. During the rotation of the rotor, gas molecules hit the blades of the true wheel 9. Therefore, it is entrained from the closed room and the required output is The turbo molecules ensure an increase in gas pressure at the mouth forced into the passageway of the gas evacuation stage. It will be done.

The gas molecules are then transferred from passage 3 of the turbomolecular gas exhaust stage to the passage 3 of the molecular gas exhaust stage. 4, so that the pressure of the discharged gas stream at their outlet is 1 The molecules of the gas emitted in the zeroth order, which rises from O-2Pa to 10-' Pa, are Flows through the shaped space 47 and gaps 46 and 45 into the additional passage 36 of the dynamic seal. The molecules of the exhausted gas pass through the gap 38 into the main passage 3 of the dynamic seal. 4 and the gas pressure at their outlet rises to the level of atmospheric pressure. The gas discharged in the passage 39, 40 of the bearing 16, the gap 41 and the bush 42 It flows through the hole 43 and then through the passage 44 of the gauging 2o to the atmosphere.

The dynamic seal acts as an auxiliary vacuum pump to raise the pressure to atmospheric levels and The evacuated space of the closed chamber is not contaminated with hydrocarbons.

The exhausted gas flow then passes through an additional passage 36 in the dynamic seal and its The pressure increases by a factor of at least 5 5 thus evacuation in the main passage 34 of the dynamic seal. This reduces the differential pressure of the gas flow caused by This reduces the equatorial moment of inertia of the rotating shaft 14 due to the rotor 2, and This makes it possible to increase the rotational speed of the motor 2.

This turbomolecular vacuum pump by at least 20% without changing its dimensions improve the emission characteristics of

A groove 50 whose depth gradually decreases from the gas pressure side N to the gas suction side V (Fig. ) is the pressure of the gas passing through the additional passage 36 of the dynamic seal formed by , enough to improve the discharge characteristics of turbomolecular vacuum pumps by at least 30%. rise to a degree.

A groove 52 whose depth gradually decreases from the gas suction side V to the gas compression side N (Fig. ) is the pressure of the gas passing through the additional passage 36 of the dynamic seal formed by , is increased by almost 5 times, which means that the discharge characteristics of turbomolecular vacuum pumps are increased by at least 20% only allows you to be enhanced.

However, an important advantage of this dynamic seal additional passage 36 design is that the passage These passages provide resistance to frictional flow of gas. of the turbomolecular vacuum pump in case of a sudden pressure increase in the space 47. The purpose is to prevent damage.

Possibility of industrial application The turbomolecular vacuum pump of the present invention can be used, for example, in electronics for making microcircuits. vacuum at a residual gas pressure of 10-'Pa to 10-'Pi. In various technical facilities for establishing and maintaining, as well as for grinding operations operating under vacuum. research equipment and instruments, such as mass spectrometers and particle accelerators in electron microscopes. and can be used effectively.

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Claims (3)

[Claims] 1. The hollow stator (1) connects the hollow rotor (2) with the turbomolecular gas between the two. A passage (3) is provided for the discharge stage, and the passage (3) has a communication hole with the atmosphere. of the molecular gas evacuation stage communicating with the passageway (34) of the kinetic seal which has been drilled. It is connected to the gas exhaust passage (4) and is provided inside the hollow rotor (2). Also, by the inner surface of the bearing (16) supporting the shaft (14) of the motor (2), A groove cut into the outer surface portion (35) of the multi-start rectangular thread-shaped shaft (14) The depth of the groove gradually decreases from the gas suction side to the gas compression side. In some turbomolecular vacuum pumps, the main dynamic seal passage (34) and The inner surface of the rotor (2) ( 37), and a bearing (1) facing said portion (37). 6) an auxiliary dynamic seal passageway (36) defined by the outer surface of the auxiliary dynamic seal; A turbo molecular vacuum pump characterized by being provided with. 2. The main and auxiliary dynamic seal passageways (34, 36), the grooves (48, 50) of the auxiliary passageway (36) are configured. A claim characterized in that the depth gradually decreases from the gas compression side to the gas suction side. The turbomolecular vacuum pump according to item 1. 3. Main and auxiliary dynamic seal passageways (34, 36) with threads in the same direction. ), the depth of the groove (51) of the auxiliary passage (36) is A claim characterized in that the range gradually decreases from the gas suction side to the gas compression side. 1. The turbomolecular vacuum pump according to 1.