JPH10306789A - Molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sublimation of exhaust gas positively at a low cost without heating a bearing part. SOLUTION: A casing 31 is formed of material of low heat conduction. A first heater 56 is provided at the exhaust side end part of the casing 31. An annular heat transfer body 52 is brought into contact with the casing 31, and an end part 52a is fitted opposedly to the inner peripheral surface 37b of the exhaust side end part of a rotor 37 so as to form an annular exhaust passage 55 jointly by the end face 37a of the rotor 37 and the inner peripheral surface 31a of the casing 31. An annular heat insulator 51 is provided between the annular heat transfer body 52 and a base 32. An exhaust pipe 57 communicated with the annular exhaust passage 55 is provided with a second heater 58. The annular exhaust passage 55, the exhaust pipe 57 and the exhaust side end part of the rotor 37 are locally heated by heating the first heater 56 and second heater 58. As a result, sublimation of exhaust gas can be prevented with a small quantity of heat, and bearing part can be protected from heat at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an improvement of a molecular pump.

[0002]

2. Description of the Related Art There is a turbo molecular pump as a molecular pump for making a high vacuum in a chamber. As shown in FIG. 2, the turbo molecular pump includes a cylindrical casing 1, a base 2 supporting the casing 1, a motor housing 3 provided in the casing 1 on the base 2, Bearings 4 and 5 provided in motor housing 3
And a rotor 7 fixed to the rotating shaft 6. On the outer periphery of the rotor 7, rotor blades 8 are provided in multiple stages. Further, stator blades 9 are provided in multiple stages on the inner peripheral surface of the casing 1 and are arranged between the rotor blades 8, 8,.

The flange 13 of the casing 1
The gas sucked through a suction port 14 from a chamber (not shown) connected to the
And forced exhaust is performed toward the exhaust port 15. Reference numeral 16 denotes an oil tank provided at the bottom of the base 2. Reference numeral 17 denotes a high frequency motor.

When the process gas in the chamber is exhausted, the gas sucked from the intake port 14 may be sublimated to be a product and deposited in the turbo molecular pump. Such products are likely to accumulate on the exhaust side of the rotor 7 on the high pressure side, and a failure occurs due to clogging or the like by the accumulated products. Accordingly, a heater 18 is provided in close contact with the bottom of the base 2, and the base 2 is heated by the heater 18, the heat of the base 2 is transmitted to the spacer 19, and the end of the casing 1 and the end of the rotor 7 are exhausted. The part is heated. By doing so, the exhaust gas is not heated and does not sublime.

[0005]

However, the above-mentioned conventional turbo-molecular pump has the following problems.
In this turbo molecular pump, since the motor housing 3 is provided on the base 2, when the base 2 is heated, the motor housing 3 is also heated. However, the bearings 4 and 5 are provided in the motor housing 3, and in order to protect the bearings 4 and 5 from burning, etc., the temperature of the motor housing 3 is set to about 80 ° C.
Nothing more. Therefore, there is naturally a limit to the temperature rise at the exhaust-side end of the rotor 7, and there is a problem that sublimation of the process gas cannot be effectively prevented.

Therefore, in the turbo-molecular pump shown in FIG. 2, a cooling plate 20 is attached to the bottom of the oil tank 16, and cooling water is passed through a drainage pipe 21 extending around the cooling plate 20, whereby the inside of the oil tank 16 is cooled. Cool the oil. Then, the bearings 4 and 5 are cooled by the cooled oil. In this case, the control means 22 controls the control signal c according to the difference between the temperature a of the base 2 detected by the sensor 23 and the target value b.
Is output to control the opening and closing of a solenoid valve 25 interposed in a cooling water supply pipe 24. Therefore,
If sublimation of exhaust gas is to be reliably prevented while protecting the bearings 4 and 5 from burning or the like, there is a problem that a complicated oil cooling device is required, leading to an increase in cost. Further, since the oil tank 16, the rotating shaft 6, the bearings 4, 5 and the like which have been heated once are cooled, there is a problem that the energy loss is large.

An object of the present invention is to provide an inexpensive molecular pump which can surely prevent sublimation of exhaust gas without heating a bearing portion.

[0008]

According to a first aspect of the present invention, there is provided a molecular pump including a casing in which a rotor is fitted, and a rotating shaft of the rotor which is fitted in the rotor. A housing, an annular heat transfer body disposed between the exhaust side end of the casing and the housing, and partially facing the inner peripheral surface of the rotor; and the annular heat transfer body and the housing. And an annular heat insulator that insulates between the annular heat transfer element and the housing, and a heating unit that heats the annular heat transfer element.

According to the above configuration, when the annular heat transfer member is heated by the heating means, the exhaust side in the casing and the inner peripheral surface of the rotor are heated by radiant heat from the annular heat transfer member, and the exhaust gas is exhausted. Sublimation is prevented. In that case, the housing is not heated because the space between the annular heat transfer element and the housing is insulated by the annular heat insulator. Therefore, the rotating shaft and the bearing supported by the housing are not heated, and the bearing is protected from burning. In addition, only necessary portions are efficiently heated by a locally small amount of heat.

According to a second aspect of the present invention, in the molecular pump according to the first aspect of the present invention, the annular heat transfer body is in contact with the casing, and the heating means is provided on an outer peripheral surface of the casing. The heater is configured to indirectly heat the annular heat transfer body via the casing.

According to the above configuration, the exhaust part of the molecular pump is heated from the outside and the inside by the casing and the annular heat transfer body. Thus, the temperature of the entire exhaust part of the present molecular pump is uniformly increased.

According to a third aspect of the present invention, in the molecular pump according to the first aspect of the present invention, the heating means is a heater attached to the annular heat transfer body to directly heat the annular heat transfer body. It is characterized by:

According to the above configuration, the annular heat transfer body is directly heated, and the exhaust portion including the exhaust-side end of the rotor is efficiently heated.

According to a fourth aspect of the present invention, in the molecular pump according to the first aspect of the present invention, an annular exhaust formed by the inner peripheral surface of the casing, an exhaust-side end surface of the rotor, and the annular heat transfer member. A passage and an exhaust pipe communicating with the annular exhaust passage are provided.

According to the above configuration, the temperature inside the annular exhaust passage is increased by the annular heat transfer member heated by the heating means and the exhaust-side end face of the rotor heated by the radiant heat from the annular heat transfer member. Is done. Therefore, the temperature of the exhaust gas flowing toward the exhaust pipe in the annular exhaust passage does not decrease and the exhaust gas does not sublime.

According to a fifth aspect of the present invention, there is provided the molecular pump according to the fourth aspect of the present invention, further comprising a heater provided in the exhaust pipe.

According to the above configuration, the temperature of the exhaust gas flowing into the exhaust pipe from the annular exhaust passage does not decrease, and the exhaust gas does not sublime in the exhaust pipe.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows a schematic cross section of the molecular pump of the present embodiment and a temperature distribution of each part during operation. The molecular pump in the present embodiment is a turbo molecular pump.

In FIG. 1A, a casing 31, a motor housing 33, bearings 34 and 35, a rotating shaft 36, a rotor 37, a flange 43, an intake port 44, an exhaust port 45, and a high-frequency motor 47 are provided by a turbo motor shown in FIG. Casing 1, motor housing 3, bearings 4, 5,
Rotary shaft 6, rotor 7, flange 13, intake port 14, exhaust port 1
5 and the high-frequency motor 17 have the same basic configuration and function similarly. In addition, rotor blades are provided on the outer periphery of the rotor 37 in the same manner as the turbo molecular pump shown in FIG. 2, while stator blades are provided on the inner periphery of the casing 31. The pump unit 40 is constituted.

The base 32 incorporates an oil tank 36, and has a cooling water passage 48 formed therein. Then, between the base 32 and the casing 31, an annular heat insulator 51 and an annular heat exchanger 52 are laminated in order from the base 32 side, and the base 32, the annular heat insulator 51, the annular heat exchanger 52 and the lower part of the casing 31 are arranged. Bolt 5 integral with flange 53
No.4. That is, in the present embodiment, the base 32 and the motor housing 33 constitute the housing.

The annular heat transfer body 52 is formed of aluminum or copper, and has a central side bent cylindrically toward the intake side along the outer peripheral surface of the motor housing 33. The annular heat transfer body 52 and the inner peripheral surface 31 of the casing 31
An annular exhaust passage 55 is formed, which is surrounded by a and the exhaust-side end face 37a of the rotor 37. In addition, the annular heat transfer body 52
Is opposed to the exhaust-side end 37b of the inner peripheral surface of the rotor 37, and the interval between the two opposed portions 52a and 37b is reduced to form an annular exhaust passage 55a.
The seal portion A is configured so that the exhaust gas inside does not flow into the motor housing 33.

In the present embodiment, the casing 31
A first heater 56 as a heating means is provided at a position corresponding to the annular exhaust passage 55 on the outer peripheral surface thereof, which is formed of stainless steel having poor heat conductivity. Also,
An exhaust pipe 57 having an exhaust port 45 is attached to the exhaust side of the casing 31 so as to communicate with the annular exhaust passage 55, and an outer peripheral surface of the exhaust pipe 57 is provided with a second
A heater 58 is provided.

The above-structured molecular pump operates as follows. That is, the first heater 56 and the second heater 5
8 is heated to a predetermined temperature under the control of heating control means (not shown). Then, the exhaust side of the casing 31 and the exhaust pipe 57 are heated. Further, the heat of the first heater 56 is transmitted to the annular heat transfer body 52 via the lower flange 53 of the casing 31. Then, the radiant heat from the annular heat transfer body 52 causes the annular exhaust passage 5
5 is heated from the side opposite to the casing 31. Further, since the end 52a on the intake side of the annular heat transfer body 52 and the inner peripheral surface 37b of the end on the exhaust side of the rotor 37 face each other, the radiant heat from the end 52a of the annular heat transfer body 52 causes The end of 37 is heated.

Here, as described above, the annular heat insulator 51 is interposed between the annular heat transfer body 52 heated by the first heater 56 and the base 32. Therefore, the base 32 is not heated by the conduction heat from the annular heat transfer body 52. As a result, the base 32
The motor housing 33 provided above is not heated. However, the outer peripheral surface of the motor housing 33 and the bent portion of the annular heat transfer body 52 need to be separated to some extent.

In general, the flange 4 of the casing 31
It is in each part of the exhaust section on the high-pressure side that products generated by sublimation of the process gas from a chamber (not shown) connected to 3 are easily deposited. Therefore, the location to be heated by the heating means in the turbo molecular pump is
7, the exhaust side end, the annular exhaust passage 55 and the exhaust pipe 57
It is. FIG. 1B shows a casing 31, a rotor 37, and a base 3 in the turbo-molecular pump of the present embodiment.
2 shows a temperature distribution of Example 2.

In the present embodiment, the casing 31 is made of stainless steel having poor heat conductivity. Therefore, in the casing 31, only the first heater 56 is efficiently heated without heat escaping to the intake side. Therefore, as shown in FIG. 1 (b), the temperature at the intake side end is about 20 ° C., whereas the location of the first heater 56 (that is, the location of the annular exhaust passage 55) is about 120 ° C. Has become. An annular heat insulator 51 is interposed between the annular heat transfer body 52 and the base 32. Therefore, while the temperature of the exhaust-side end of the casing 31 is about 120 ° C., the temperature of the boundary between the base 32 and the annular heat insulator 51 is sufficiently low at about 40 ° C. It turns out that it works enough.

Furthermore, the end 52a on the intake side of the annular heat transfer body 52 is connected to the end 3 on the inner peripheral surface of the rotor 37 on the exhaust side.
7b, the end of the rotor 37 is heated by radiant heat from the annular heat transfer body 52. Therefore, as shown in FIG. 1B, the end on the exhaust side of the rotor 37 is heated to substantially the same temperature as the exhaust side of the casing 31. Therefore, the exhaust-side end of the rotor 37 and the annular exhaust passage 55 are heated to 100 ° C. or higher, and the exhaust gas that has passed through the pump unit 40 and has reached the annular exhaust passage 55 is in the annular exhaust passage 55. It does not sublimate and deposit. Further, the exhaust pipe 57 is also actively heated by the second heater 58, so that the temperature of the high-pressure exhaust gas does not decrease in the exhaust pipe 57 and the exhaust gas does not sublime in the exhaust pipe 57.

The temperature of the end of the casing 31 on the intake side is about 20 ° C., while the temperature of the end of the rotor 37 on the intake side is as high as about 90 ° C. This is the casing 3
Since the end on the intake side of 1 is made of stainless steel having poor heat conduction, heat from the first heater 56 and heat from the pump section 40 are not transmitted much. Heat is dissipated by convection. On the other hand, the end of the rotor 37 on the intake side is caused by only radiation by radiation.

Furthermore, the end 52a on the intake side of the annular heat transfer body 52 is connected to the end 3 on the inner peripheral surface of the rotor 37 on the exhaust side.
The sealing portion A is opposed to the sealing portion 7b at a small interval. Therefore, the flow of the exhaust gas in the annular exhaust passage 55 into the motor housing 33 is restricted. Further, since the seal portion A is heated by the radiant heat from the end portion 52a of the annular heat transfer body 52, the exhaust gas that has entered the motor housing 33 does not sublime. Therefore, the product due to the sublimation does not adhere to the inner peripheral surface 37b at the end of the rotor 37, and the seal portion A is not clogged.

As described above, in the present embodiment, the first heater 56 is provided at the end on the exhaust side of the casing 31 formed of a material having poor heat conductivity, while the second heater 58 is provided on the exhaust pipe 57. Provide. Further, an annular heat transfer body 52 whose central portion is cylindrically bent toward the intake side is attached in contact with the lower flange 53 of the casing 31, and the end face 37 a on the exhaust side of the rotor 37 and the inner periphery of the casing 31 are attached. An annular exhaust passage 55 surrounded by the surface 31a and the annular heat transfer body 52 is formed. In addition, the end 52a on the intake side of the annular heat transfer body 52 and the inner peripheral surface 3
7b and the annular heat transfer body 52 and the base 3
2, an annular heat insulator 51 is provided.

Therefore, by heating the first heater 56 and the second heater 58, the annular exhaust passage 5 is heated.
5, the exhaust pipe 57 and the exhaust-side end of the rotor 37 can be locally heated, so that the temperature of the entire rotor 37 does not exceed 120 ° C., which is the heat-resistant temperature of aluminum. Further, since the annular heat insulator 52 and the base 32 are insulated, the motor housing 33 is kept at 80 ° C. or lower. Therefore, the bearings 34 and 35 can be protected from burning and the like at low cost without using a complicated oil cooling device or the like. Further, since only the portion to be heated is locally heated so as not to sublime the exhaust gas, sublimation of the exhaust gas can be prevented with a small amount of heat. Further, the annular exhaust passage 55, the exhaust pipe 57, and the end 37b of the inner peripheral surface of the rotor 37.
Can be heated to substantially the same temperature, and the product does not selectively adhere to any part of the exhaust part.

Further, an end 52a on the intake side of the annular heat transfer body 52 is opposed to an end 37b on the exhaust side of the inner peripheral surface of the rotor 37 at a narrow interval to form a seal portion A. Therefore, it is possible to restrict the exhaust gas in the annular exhaust passage 55 from flowing into the motor housing 33. The seal portion A is heated by radiant heat from the end portion 52a of the annular heat transfer body 52. Therefore, sublimation of the exhaust gas that has entered the motor housing 33 can be prevented, and clogging of the seal portion A can be eliminated.

In the above embodiment, the heating means for heating the annular heat transfer member 52 is constituted by the first heater 56 provided at a position corresponding to the annular exhaust passage 55 on the outer peripheral surface of the casing 31. I have. Then, the first heater 56 indirectly heats through the lower flange 53. However, the present invention is not limited to this, and the heating means may be constituted by a bar heater to directly heat the annular heat transfer body 52.

[0034]

As is apparent from the above description, the molecular pump according to the first aspect of the present invention has a structure in which the inner peripheral surface of the rotor is provided between the exhaust side end of the casing and the housing that supports the rotating shaft of the rotor. An annular heat transfer body, which is partially opposed, is provided, and the annular heat transfer body is heated by a heating unit, and the annular heat transfer body and the housing are insulated by an annular heat insulator. The exhaust side in the casing and the inner peripheral surface of the rotor can be heated by radiant heat from the heat body. Therefore, the exhaust gas passing through the exhaust side in the casing can be heated to prevent sublimation.

In this case, since the space between the annular heat transfer element and the housing is insulated by the annular heat insulator, the rotating shaft and the bearing supported by the housing are not heated. Therefore, the bearing portion can be protected from burning and the like without using a complicated cooling device. Furthermore, since only the portion necessary for preventing the exhaust gas from sublimating is locally heated, it can be efficiently heated with a small amount of heat.

In the molecular pump according to the second aspect of the present invention, the annular heat transfer member is indirectly heated via the casing by the heater as the heating means provided on the outer peripheral surface of the casing. The entire exhaust part of the molecular pump can be uniformly heated from the outside and the inside. Therefore,
The product generated by the sublimation of the exhaust gas does not selectively adhere to any part of the exhaust part.

In the molecular pump according to the third aspect of the present invention, the annular heat transfer element is directly heated by the heater as the heating means attached to the annular heat transfer element. The exhaust part can be efficiently heated.

In the molecular pump according to the present invention, an annular exhaust passage is formed by the inner peripheral surface of the casing, an exhaust-side end surface of the rotor, and the annular heat transfer member. Since the exhaust pipe communicating with the annular exhaust passage is provided, the inside of the annular exhaust passage is raised by the annular heat transfer body heated by the heating means and the end face of the rotor heated by radiant heat from the annular heat transfer body. Warmed up. Therefore, the exhaust gas flowing toward the exhaust pipe in the annular exhaust passage does not sublime due to a decrease in temperature.

Further, in the molecular pump according to the fifth aspect of the present invention, since the heater is provided in the exhaust pipe, the temperature of the exhaust gas flowing into the exhaust pipe from the annular exhaust passage does not decrease. Therefore, the exhaust gas does not sublime in the exhaust pipe.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a turbo molecular pump as a molecular pump of the present invention and a temperature distribution of each part.

FIG. 2 is a cross-sectional view of a conventional turbo-molecular pump.

[Explanation of symbols]

31 ... casing, 32 ... base,
33: motor housing, 36: rotating shaft,
37 ... rotor, 40 ... pump part, 45 ... exhaust port, 47 ... high frequency motor, 51 ... annular heat insulator, 52
... annular heat transfer body, 53 ... lower flange,
55: annular exhaust passage, 56: first heater,
57: exhaust pipe, 58: second heater.

Claims (5)

[Claims] A casing (3) in which a rotor (37) is fitted.
1), a housing (32, 33) fitted inside the rotor (37) and supporting a rotation shaft (36) of the rotor (37); an exhaust-side end of the casing (31); and the housing (32, 33), and an annular heat exchanger (52) partially facing the inner peripheral surface (37b) of the rotor (37); 52) and the housing (32, 33), and the annular heat transfer body (52) and the housing (3).
A molecular pump comprising: an annular heat insulator (51) that insulates the annular heat transfer member (2, 33); and a heating means (56) for heating the annular heat transfer member (52). 2. The molecular pump according to claim 1, wherein the annular heat transfer body (52) is in contact with the casing (31), and the heating means is provided on an outer peripheral surface of the casing (31). Installed, and the annular heat transfer element (52) is connected to the casing (31).
A molecular pump characterized by being a heater (56) for indirectly heating through a heater. 3. The molecular pump according to claim 1, wherein said heating means is a heater attached to said annular heat transfer body (52) and directly heating said annular heat transfer body (52). And molecular pump. 4. The molecular pump according to claim 1, wherein the inner peripheral surface (31a) of the casing (31) is connected to the rotor (3).
7) and the end surface (37a) on the exhaust side and the annular heat transfer body (5).
A molecular pump comprising: an annular exhaust passage (55) formed in 2); and an exhaust pipe (57) communicating with the annular exhaust passage (55). 5. The molecular pump according to claim 4, further comprising a heater (58) provided in said exhaust pipe (57).