JPH0589888U - Dry vacuum pump shaft seal device - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a shaft seal device for a rotary shaft in a dry vacuum pump, which avoids the use of oil and mechanical rotary contact and maintains a high vacuum. A dry vacuum pump shaft seal device is provided with (1) an outer sleeve 7 attached to a partition 2 between a pump chamber and a motor chamber in a pump casing 1 and a rotor 5 penetrating the inner peripheral surface and the partition. A radial labyrinth seal 8 formed between the outer peripheral surface of the inner sleeve 6 fitted to the rotating shaft 3, (2) a slinger 10 formed between the rotor and the outer sleeve, and (3) an axial labyrinth. The seal 11 is provided with one of the three alternatives or in an appropriate combination, and if necessary, in the radial labyrinth seal area, or in the radial labyrinth seal area, slinger, or axial labyrinth seal on the pump chamber side, for the passage of inert gas. 1
4 and 15 open, and oil return through holes 16 and 17 on the motor chamber side
Is open.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a dry vacuum pump, and more particularly to a shaft seal device for a dry vacuum pump.

[0002]

[Prior Art]

 In a conventional dry vacuum pump, an oil seal or a mechanical seal is used for a shaft seal device for a rotating shaft between a pump chamber and a motor chamber.

[0003]

[Problems to be solved by the device]

 The oil seals and mechanical seals used in the shaft seal device for the rotary shaft in the conventional dry vacuum pump described above use (1) oil, so that oil leakage occurs, (2) load torque increases, and (3) ) There are problems such as short life and (4) heat generation. The oil seal is 220 ° C or less, the peripheral speed of the sealing surface is 30 m / sec or less, and the mechanical seal is the peripheral speed of the sealing surface is 100 m / sec or less. Mechanical seals are expensive due to usage conditions.

The present invention provides a shaft seal device for a rotary shaft in a dry vacuum pump that does not have such problems and has no use condition.

[0005]

[Means for Solving the Problems]

 The shaft sealing device for a dry vacuum pump according to the present invention is (1) a rotary shaft having a rotor attached to an inner peripheral surface of an outer sleeve attached to a partition between a pump chamber and a motor chamber in a pump casing and a rotor. Radial labyrinth seal formed between the outer peripheral surface of the rotor and the outer peripheral surface of the inner sleeve fitted to the rotating shaft, (2) slinger formed between the rotor and the outer sleeve, and (3) axial labyrinth. The seals are equipped with one of the three alternatives or in an appropriate combination.For the outflow of inert gas, which is opened from the radial labyrinth seal area, the radial labyrinth seal area, the slinger or the axial labyrinth seal to the pump chamber side as required. Through hole and radial labyrinth seal area, radial labyrinth seal area, slinger or axial labyrinth seal Opening the oil return for hole is formed over data chamber side.

[0006]

[Action]

 In the dry vacuum pump, when the rotary shaft is driven to rotate at high speed, the inner sleeve rotates together with the rotor with respect to the fixed outer sleeve. The inert gas (for example, nitrogen) supplied from the through hole flows through the seal part and is discharged from the discharge port together with the exhaust gas.

In this way, air leakage from the motor chamber side through the rotation gap between the fixed-side partition wall and the rotary shaft that penetrates the partition wall is blocked. Moreover, since the labyrinth seal and the slinger are not in mechanical contact with each other in the inner and outer sleeves, there is no friction, the rotation of the rotary shaft is not hindered, and no friction heat is generated.

[0008]

【Example】

 A shaft sealing device in a dry vacuum pump according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the interior of the pump casing 1 is divided into a pump chamber and a motor chamber by a partition wall 2, and a rotary shaft 3 which is driven to rotate by a motor (not shown) is supported by rolling bearings 4 in the partition wall 2 and is installed in the pump chamber. The rotor 5 is attached and protrudes. On the upper surface of the partition wall 2, a shaft sealing device is provided adjacent to the rolling bearing 4 in a coaxial relationship.

To describe the shaft sealing device, the inner sleeve 6 fitted to the rotary shaft 3 is fitted to the outer sleeve 7 attached to the upper surface of the partition wall 2 in contact with the flange portion 71. A suitable number of circumferential irregularities formed on the outer peripheral surface of the inner sleeve 6 and the inner peripheral surface of the outer sleeve 7 mesh with each other to form a radial labyrinth seal 8.

As shown in FIG. 2, an appropriate number of circumferential irregularities on the outer peripheral surface of the inner sleeve 6 forming the radial labyrinth seal 8 are directly formed on the outer peripheral surface of the rotary shaft 3, and the inner sleeve 6 is It may be omitted.

The upper half of the outer sleeve 7 is fitted into a recess 9 formed in the center of the lower end of the rotor 5, and a slinger 10 is formed on the outer peripheral surface of the outer sleeve 7 at the upper end thereof, and a slinger is formed at the middle portion thereof. The unevenness forming the axial labyrinth seal 11 is formed by meshing with the unevenness in the circumferential direction formed on the inner edge side of the lower end surface of the rotor 5.

The radial labyrinth seal 8, the slinger 10 and the axial labyrinth seal 11 are provided alternatively or in combination.

In the radial labyrinth seal area of the inner peripheral surface of the outer sleeve 7, upper and lower circumferential grooves 12 and 13 are formed in the circumferential direction, and the through hole 14 opened in the upper groove 12 is formed in the partition wall 2. The through hole 15 opened on the upper surface and the through hole 16 opened on the lower groove 13 are connected to the through hole 17 opened on the upper surface of the partition wall 2.

As shown in FIG. 2, the upper groove 12 on the inner peripheral surface of the outer sleeve 7 is not provided, and the through hole 14 opens to the upper end surface of the outer sleeve 7 and directly communicates with the recess 9 of the rotor 5. Alternatively, instead of the lower groove 13, a circumferential groove 20 is formed on the lower end surface of the flange portion 71 of the outer sleeve 7, and the circumferential groove 20 passes through the through hole 21 in the radial direction. May be in communication with.

The through hole 15 is connected to an inert gas (for example, nitrogen) supply source (not shown). The pump casing 1 is formed with a through hole (not shown) opened at an intermediate portion in the axial direction of the pump chamber, and the through hole is also connected to an inert gas (for example, nitrogen) supply source (not shown).

The lower end surface of the rotor 5 faces a space 19 communicating with a discharge port 18 opened in the pump casing 1. The radial labyrinth seal 8 may be a thin labyrinth ring, instead of an appropriate number of circumferential projections and depressions that mesh with the outer peripheral surface of the inner sleeve 6 and the inner peripheral surface of the outer sleeve 7. The thin labyrinth ring is fitted in, for example, the inner peripheral surface of the outer sleeve 7 and the concave portion of the outer peripheral surface of the inner sleeve 6.

In the dry vacuum pump, when the rotating shaft 3 is driven to rotate at high speed by the motor, the inner sleeve 6 rotates together with the rotor 5. During the rotation, the labyrinth seals 8 and 11 and the slinger 10 block the leakage of exhaust fluid from the motor chamber through the rotation gap between the stationary partition wall 2 and the rotary shaft 3 penetrating the partition wall 2. Moreover, since the labyrinth seal and the slinger are not in mechanical contact with each other on the inner and outer sleeves, there is no friction, the rotation of the rotary shaft 3 is not hindered, and no friction heat is generated.

When the rotor 5 rotates, the inert gas (for example, nitrogen gas) supplied from the through hole 15 flows through the through hole 14, flows out into the upper groove 12 or directly into the recess 9 of the rotor 5, It flows from the upper end of the sleeve 7 to the outside of the slinger 10 and the axial labyrinth seal 11, is discharged together with the exhaust gas from the discharge port 18 through the space 19, and also has a through hole (not shown) which is opened at an intermediate portion in the axial direction of the pump chamber. The inert gas (for example, nitrogen gas) supplied from (1) flows through the peripheral surface of the rotor 5, passes through the space 19, and is discharged from the discharge port 18 together with the exhaust gas.

By such an inert gas (for example, nitrogen gas) purging, formation and condensation of reactants in the exhaust gas are prevented, and flammable exhaust gas is diluted during exhaust, Safety is achieved. When vacuum grease is used for the shaft seal device, the sealing effect is further enhanced. The lubricant from the rolling bearing 4 side is discharged from the lower groove 13 or the circumferential groove 20 of the outer sleeve 7 through the through hole 16 or the through hole 17 through the through hole 17.

[0020]

[Effect of the device]

 According to the shaft seal device for the rotary shaft in the dry vacuum pump of the present invention, since oil is not used, there is no fear of oil leakage, and it is suitable for preventing foreign matter from entering as in semiconductor manufacturing equipment.

Since there is no mechanical contact between the rotating side and the fixed side, the load torque is not affected, the rotational speed of the seal surface is not restricted, rotational friction heat is not generated, and the life is extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a shaft seal device for a dry vacuum pump according to an embodiment of the present invention.

FIG. 2 is a sectional view of a shaft seal device for a dry vacuum pump according to another embodiment of the present invention.

[Explanation of symbols]

 1 Pump Casing 2 Partition 3 Rotating Shaft 4 Rolling Bearing 5 Rotor 6 Inner Sleeve 7 Outer Sleeve 71 Flange 8 Radial Labyrinth Seal 9 Recess 10 Slinger 11 Axial Labyrinth Seal 12 Upper Groove 13 Lower Groove 14, 15, 16, 17, 21 Through Hole 18 Discharge port 19 Space 20 Circumferential groove

Claims (7)

[Scope of utility model registration request] 1. An inner peripheral surface of an outer sleeve attached to a partition wall between a pump chamber and a motor chamber in a pump casing and an outer peripheral surface of a rotary shaft having a rotor attached and penetrating through the partition wall and fitted to the rotary shaft. A dry vacuum pump shaft sealing device having a radial labyrinth seal configured between the inner sleeve and the outer peripheral surface thereof. 2. An outer peripheral surface of an outer sleeve attached to a partition wall between a pump chamber and a motor chamber in a pump casing and an outer peripheral surface of a rotary shaft which penetrates the partition wall and has a rotor attached thereto or an inner side fitted to the rotary shaft. A shaft sealing device for a dry vacuum pump including a radial labyrinth seal formed between the outer peripheral surface of the sleeve and a slinger and / or an axial labyrinth seal formed between the rotor and the outer sleeve. . 3. A slinger and an axial labyrinth seal formed between an outer sleeve attached to a partition between a pump chamber and a motor chamber in a pump casing and a rotor attached to a rotary shaft penetrating the partition, or the same. Dry vacuum pump shaft sealer equipped with either one. 4. The shaft sealing device for a dry vacuum pump according to claim 1, wherein a radial labyrinth seal region or an inert gas outflow through hole that is open to the pump chamber side from the radial labyrinth seal region is formed. 5. The shaft seal device for a dry vacuum pump according to claim 3, wherein an inert gas outflow through hole that is open to the motor chamber side from the slinger or the axial labyrinth seal is formed. 6. The shaft sealing device for a dry vacuum pump according to claim 1, wherein an oil return through hole that is open to the radial labyrinth seal area or to the motor chamber side from the radial labyrinth seal area is formed. 7. The shaft seal device for a dry vacuum pump according to claim 3, wherein an oil return through hole that is open to the motor chamber side from the slinger or the axial labyrinth seal is formed.