JP2002115683A - Rotary shaft in vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong service life of a contact type seal means for a shaft seal coming into slide-contact with a rotary shaft in a vacuum pump. SOLUTION: Rubber lip seals 44, 45 are arranged in protruding end parts 192, 202 of rotary shafts 19, 20. The lip seals 44, 45 come into slide-contact with peripheral faces of the protruding end parts 192, 202 of the rotary shafts 19, 20 to bring sealing action. Nickel plated layers 46, 47 are formed in sections of peripheral faces of the rotary shafts 19, 20 coming into slide-contact with the lip seals 44, 45. The lip seal 44 comes into slide-contact with the nickel plated layer 46, and the lip seal 45 comes into slide-contact with the nickel plated layer 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary shaft in a vacuum pump which moves a gas transfer member in a pump chamber based on rotation of a rotary shaft and transfers gas by the operation of the gas transfer member to provide a suction action. It is.

[0002]

2. Description of the Related Art A vacuum pump disclosed in Japanese Patent Application Laid-Open No. 2-157490 and Japanese Patent Application Laid-Open No.
The rotor is rotated in a state where two adjacent rotors are engaged with each other. The rotating operation of the two rotors rotating while meshing transfers gas. One of the rotation axes of the rotor is
The driving force is obtained from the motor, and the other rotating shaft receives the driving force from the one rotating shaft via a gear mechanism.

[0003] Lubricating oil is stored in a housing that houses the gear mechanism, and the stored oil lubricates the gear mechanism. In order to prevent the lubricating oil from leaking into the pump chamber, a lip seal is provided between a housing part of the rotary shaft and a housing part penetrating a housing wall separating the housing chamber of the gear mechanism and the pump chamber. .

[0004]

As a rotating shaft, spheroidal graphite cast iron is used to improve hardness. Spheroidal graphite cast iron is cast iron containing graphite having an average particle diameter of about 30 to 100 μm. When the peripheral surface of the cast iron rotary shaft is ground, graphite particles may peel off from the peripheral surface of the rotary shaft, leaving holes in the traces of graphite exfoliation. The presence of this hole causes damage to the sliding contact portion of the lip seal that slides on the peripheral surface of the rotating shaft. If the sliding contact portion of the lip seal slidingly contacting the peripheral surface of the rotating shaft is damaged, the sealing function for preventing oil leakage is reduced. That is, the life of the lip seal is shortened.

SUMMARY OF THE INVENTION It is an object of the present invention to extend the life of a contact-type sealing means for a shaft seal in sliding contact with a rotating shaft in a vacuum pump.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a gas transfer system in which a gas transfer unit in a pump chamber is moved based on rotation of a rotating shaft, and the operation of the gas transfer unit transfers gas to provide a suction effect. A vacuum pump in which contact-type sealing means for shaft sealing for preventing gas in a chamber from leaking along the peripheral surface of the rotary shaft is provided so as to slide on the peripheral surface of the rotary shaft. 1 In the invention,
The rotating shaft is made of cast iron, and a roughness reducing layer for reducing surface roughness is provided on the entire circumference of the peripheral surface of the rotating shaft where the contact-type sealing means is disposed, and the contact with the roughness reducing layer is provided. The mold sealing means was brought into contact.

[0007] The roughness reducing layer prevents the contact type sealing means, which is the sliding contact partner, from being damaged. According to a second aspect of the present invention, in the first aspect, the roughness reduction layer is a plating layer.

[0008] Plating is simple in reducing the roughness of the peripheral surface of the rotating shaft. According to a third aspect of the present invention, in the second aspect, the plating layer is a nickel plating layer.

A part of the gas in the pump chamber may reach the roughness reducing layer along the peripheral surface of the rotating shaft, and the kind of the gas may include a corrosive gas. Nickel plating excellent in corrosion resistance is suitable for avoiding corrosion due to contact with corrosive gas.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the rotating shaft is made of spheroidal graphite cast iron. Even if the graphite particles are peeled off from the peripheral surface of the rotating shaft that is in sliding contact with the contact-type sealing means, the roughness reducing layer fills the holes where the graphite particles are peeled off.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the vacuum pump arranges a plurality of the rotating shafts in parallel and arranges a rotor on each of the rotating shafts. Then, rotors on adjacent rotating shafts are meshed with each other, a plurality of meshed rotors are housed in a pump chamber as a set, and an oil-existing region separated from the pump chamber by a partition is provided through the partition. A vacuum pump having the rotating shaft protruded, wherein the contact-type sealing means is interposed between the partition and the rotating shaft, and the rotor is formed integrally with the rotating shaft.

[0012] For forming a rotating shaft integrally formed with the rotor, molding is optimal.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a roots pump will be described below with reference to FIGS.

As shown in FIG. 1, the multi-stage roots pump 11
The front housing 13 is joined to the front end of the rotor housing 12 of the first embodiment, and the closing body 36 is joined to the front housing 13. A rear housing 14 is joined to the rear end of the rotor housing 12. The rotor housing 12 includes a cylinder block 15 and a plurality of chamber forming walls 16. As shown in FIG. 2B, the cylinder block 15 includes a pair of block pieces 17 and 18, and the chamber forming wall 16 includes a pair of wall pieces 161 and 162. As shown in FIG. 1, the space between the front housing 13 and the chamber forming wall 16, the space between the adjacent chamber forming walls 16, and the space between the rear housing 14 and the chamber forming wall 16 are each a pump. Rooms 39, 40, 41, 42, 43
It has become.

A pair of rotating shafts 19, 20 are rotatably supported by the front housing 13 and the rear housing 14 via radial bearings 21, 37, 22, 38 as bearings. Both rotating shafts 19 and 20 are arranged parallel to each other. The rotation shafts 19 and 20 are passed through the chamber forming wall 16.

A plurality of rotors 23, 24,
25, 26, 27 are integrally formed, and the same number of rotors 28, 29, 30, 31, 32 are integrally formed on the rotating shaft 20. Rotating shafts 19 and 20 and rotors 23 to 32
Is made of spheroidal graphite cast iron. The rotors 23 to 32 have the same shape and the same size when viewed in the direction of the axes 191 and 201 of the rotating shafts 19 and 20. Rotors 23, 24, 25, 26,
The thickness of the rotor 27 is made smaller in this order, and the thickness of the rotors 28, 29, 30, 31, 32 is made smaller in this order. Rotor 23, 2
Numeral 8 is housed in a pump chamber 39 in mesh with each other, and rotors 24 and 29 are housed in a pump chamber 40 in mesh with each other. The rotors 25 and 30 are housed in the pump chamber 41 in a state of meshing with each other.
The pumps 6 and 31 are housed in the pump chamber 42 in a mutually engaged state. The rotors 27 and 32 are housed in the pump chamber 43 in a state of being meshed with each other.

The gear housing 3 is mounted on the rear housing 14.
3 are joined. The rotating shafts 19 and 20 pass through the rear housing 14 and protrude into the gear housing 33. The protruding ends 192 and 202 of the rotating shafts 19 and 20 are fixed to the gears 34 and 35 in a state where the gears 34 and 35 mesh with each other. Have been. An electric motor M is mounted on the gear housing 33. The driving force of the electric motor M is transmitted to the rotating shaft 19 via the shaft joint 10, and the rotating shaft 19 is rotated by the electric motor M in the direction of the arrow R <b> 1 in FIGS. 2A, 2 </ b> B, and 2 </ b> C. Is done. The rotating shaft 20 obtains a driving force from the electric motor M via the gears 34 and 35, and the rotating shaft 20 is rotated by the rotating shaft 19 as shown by an arrow R2 in FIGS. 2 (a), 2 (b) and 2 (c). And rotate in the opposite direction.

As shown in FIG. 3, lubricating oil (not shown) is stored at the bottom of a gear housing chamber 331 which houses a gear mechanism composed of gears 34 and 35. The lubricating oil is
It is picked up by the rotation operation of 35. Gears 34,3
The gear mechanism composed of 5 serves as oil scraping means for scraping the stored oil. The lubricating oil lubricates the gears 34, 35 and the radial bearings 37, 38. Rear housing 1
Reference numeral 4 denotes a partition wall that separates the pump chamber 43 from the gear housing chamber 331 which is an oil existing area. The lubricating oil cools the protruding ends 192, 202 of the rotating shafts 19, 20.

As shown in FIG. 2B, a passage 163 is formed in the chamber forming wall 16. An inlet 164 and an outlet 165 of the passage 163 are formed in the chamber forming wall 16. The adjacent pump chambers 39, 40, 41, 42, 43
They communicate with each other via a passage 163.

As shown in FIG. 2A, the block piece 18
Is formed such that an inlet 181 communicates with the pump chamber 39. As shown in FIG.
Is formed so that a discharge port 171 communicates with the pump chamber 43. The gas introduced into the pump chamber 39 from the inlet 181 is rotated by the rotation of the rotors 23 and 28 to form the chamber forming wall 1.
6 from the inlet 164 via the passage 163 to the adjacent pump chamber 40 from the outlet 165. Hereinafter, similarly, the gas flows in the order of decreasing the volume of the pump chamber, that is, the pump chamber 4
They are transferred in the order of 0, 41, 42, 43. Pump room 43
The gas transferred to the discharge port is discharged from the discharge port 171 to the outside. The rotors 23 to 32 are gas transfer bodies that transfer gas.

As shown in FIGS. 1 and 3, the rotating shaft 19,
Rubber lip seals 44 and 45 are disposed at the protruding ends 192 and 202 of 20, respectively. Lip seal 44, 4
Reference numeral 5 denotes a contact-type sealing means for a shaft seal that slides on the peripheral surfaces of the protruding ends 192 and 202 of the rotating shafts 19 and 20 to provide a sealing action. Part of the lubricating oil scraped up by the rotation of the gears 34, 35 is
Lip seal 4 via the gap between the inner ring and the outer ring
It reaches 4,45. The lip seals 44 and 45 are lubricated by the lubricating oil and cooled.

Nickel plated layers 46, 4 are provided on the peripheral surfaces of the rotating shafts 19, 20 which are in sliding contact with the lip seals 44, 45.
7 are formed. The lip seal 44 is in sliding contact with the nickel plating layer 46, and the lip seal 45 is in sliding contact with the nickel plating layer 47.

In the first embodiment, the following effects can be obtained. (1-1) The rotating shaft 19 (20) and the rotors 23 to 27 (28
In the configuration in which the rotors 23 to 32 are specially formed, mold forming is optimal for forming the rotating shafts 19 and 20. Therefore, the rotating shafts 19 and 20 are made of cast iron, and the rotating shafts 19 and 20 and the rotors 23 to 3 are further formed.
Spheroidal graphite cast iron is used to increase the hardness of No. 2. When the peripheral surfaces of the rotating shafts 19 and 20 made of such a material are ground, spherical graphite particles are peeled off from the peripheral surfaces of the rotating shafts 19 and 20, and holes are formed in the traces. The lip seals 44, 4 are provided on the peripheral surfaces of the rotating shafts 19, 20 having such holes.
When the sliding contact is made, the lip seals 44 and 45 are damaged,
The lubricating oil in the gear storage chamber 331 is
And enters the pump chamber 43 side beyond the contact portion between the shaft and the rotating shafts 19 and 20.

The nickel plating layer 46, which is a roughness reducing layer,
Reference numeral 47 denotes a hole filled with traces of exfoliation of the spherical graphite particles, and lip seals 44 and 45 include nickel plating layers 46 and 4 having low roughness.
7 is in sliding contact. Therefore, the lip seals 44 and 45 are not damaged by sliding contact with the sliding contact partner, and the life of the lip seals 44 and 45 is extended.

(1-2) The peripheral surfaces of the rotating shafts 19 and 20 are plated, for example, by projecting ends 192 and 2 from the rotors 27 and 32.
It is as simple as masking the non-plated portion on the 02 side and plating the protruding end portions 192 and 202 on the plating solution. Moreover, the plating surely closes the minute holes in the traces of the exfoliation of the spherical graphite particles. Therefore, plating is simple in reducing the roughness of the peripheral surfaces of the rotating shafts 19 and 20.

(1-3) Corrosive gas is a kind of gas transferred by the vacuum pump. The corrosive gas in the pump chamber 43 flows between the rear housing 14 and the rotating shafts 19 and 20 along the peripheral surfaces of the rotating shafts 19 and 20 so that the lip seal 4
It may reach 4,45 sites. Therefore, it is necessary to form the roughness reducing layer for preventing the lip seals 44 and 45 from being damaged by a material which does not corrode by corrosive gas. Nickel is optimal as a material that does not corrode by corrosive gas handled by a vacuum pump.

(1-4) The nickel plating layers 46, 47 for reducing the roughness of the peripheral surfaces of the rotating shafts 19, 20 reduce the sliding contact resistance to the lip seals 44, 45. Reduction of the sliding contact resistance reduces power consumption for rotating the rotating shafts 19 and 20.

(1-5) Lip seals 44 and 45 made of rubber
Is extremely excellent in close contact with the peripheral surfaces of the rotating shafts 19 and 20, but without lubrication by lubricating oil, the durability is extremely reduced. The rubber lip seals 44 and 45 which are lubricated by the lubricating oil in the gear housing chamber 331 are contact-type sealing means that can ensure high durability and high sealing performance.

In the present invention, the following embodiments are also possible. (1) A solid lubricant layer is used as the roughness reducing layer.
As the solid lubricant, a mixture of molybdenum disulfide, graphite, and a polyamideimide-based thermosetting resin is preferable. Molybdenum disulfide and graphite are excellent as solid lubricants, and a polyamide-imide-based thermosetting resin functions as an adhesive. If these mixtures are applied to the peripheral surfaces of the rotating shafts 19 and 20 and then dried, a roughness reduction layer made of a solid lubricant is formed. The mixture can be applied by spray coating, pad printing, or the like.

Examples of other solid lubricants include polymers such as ethylene tetrafluoride, molybdenum disulfide, graphite, tungsten disulfide, lead oxide, boron nitride, and soft metals such as lead, gold, indium, and tin. Or a combination of two or more can be used. As the adhesive, a polyimide-based or polyimide-based thermosetting resin can be used. (2) A cylindrical member such as nickel is fitted to the rotating shafts 19 and 20 to form a roughness reducing layer. (3) A nickel plating layer is provided on a rotating shaft made of cast iron not containing graphite. Graphite-free cast iron is inferior in hardness to graphite-containing cast iron, but the nickel plating layer increases the hardness of the periphery of the graphite-free cast iron rotary shaft.

[0031]

As described above in detail, according to the present invention, the rotating shaft is made of cast iron, and the roughness for reducing the surface roughness is provided on the entire circumference of the peripheral surface of the rotating shaft where the contact-type sealing means is disposed. Since the reduction layer is provided and the contact-type sealing means is brought into contact with the roughness-reducing layer, an excellent effect is obtained in that the life of the contact-type sealing means for the shaft seal in sliding contact with the rotating shaft in the vacuum pump can be extended.

[Brief description of the drawings]

FIG. 1 shows a multi-stage roots pump 11 according to a first embodiment.
FIG.

FIG. 2A is a sectional view taken along line AA of FIG. (B) is FIG.
BB sectional drawing of FIG. (C) is a sectional view taken along line CC of FIG. 1.

FIG. 3 is an enlarged plan sectional view of a main part.

[Explanation of symbols]

11 Multistage roots pump, which is a vacuum pump. 14 ... Rear housing to be a partition. 19, 20 ... rotating shaft. 23-3
2. A rotor serving as a gas transfer body. Reference numeral 331 denotes a gear storage chamber serving as an oil existing area. 34, 35 ... gears constituting a gear mechanism.
39-43 ... Pump room. 44, 45: Lip seals serving as contact-type sealing means. 46, 47: nickel plating layers which are roughness reducing layers.

Continued on the front page (72) Inventor Hitoshi Masaji 2-1-1 Toyota-cho, Kariya-shi, Aichi F-term in Toyota Industries Corporation (reference) 3H029 AA06 AA18 AB06 BB16 BB33 CC16 CC20 CC38 3J006 AE00 AE17 AE34

Claims (5)

[Claims] 1. A gas transfer unit in a pump chamber is moved based on the rotation of a rotary shaft, and a gas is transferred by an operation of the gas transfer unit to cause a suction action. A vacuum pump in which contact type sealing means for shaft sealing for preventing leakage along the rotating shaft is slidably in contact with the circumferential surface of the rotating shaft, wherein the rotating shaft is made of cast iron, and the circumferential surface of the rotating shaft is A rotary shaft in a vacuum pump provided with a roughness reducing layer for reducing surface roughness on the entire circumference of the arrangement site of the contact-type sealing means in the above, and contacting the contact-type sealing means with the roughness-reducing layer. 2. The rotary shaft according to claim 1, wherein the roughness reducing layer is a plating layer. 3. The rotary shaft according to claim 2, wherein the plating layer is a nickel plating layer. 4. A rotary shaft in a vacuum pump according to claim 1, wherein said rotary shaft is made of spheroidal graphite cast iron. 5. The vacuum pump according to claim 1, wherein a plurality of the rotating shafts are arranged in parallel, a rotor is arranged on each of the rotating shafts, rotors on adjacent rotating shafts are meshed with each other, and the vacuum pump is in a state of being meshed with each other. A vacuum pump in which a plurality of rotors are housed in a pump chamber as one set, and the rotary shaft projects through the partition in an oil-existing region separated from the pump chamber by a partition, and the contact-type sealing means includes: The rotary shaft of the vacuum pump according to claim 1, wherein the rotary shaft is interposed between the partition wall and the rotary shaft, and the rotor is formed integrally with the rotary shaft.