JP2003120529A - Gas feeder in vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a stable dilution effect by feeding an inert gas. SOLUTION: An electromagnetic flow regulating valve 67 is fitted to a base pipe 60 on the upstream side of connection parts 541-591 of the base pipe 60 which is a feed passage of the inert gas to branched pipes 54-59. The flow regulating valve 67 regulates the flow rate of the inert gas flowing in the base pipe 60. The flow regulating valve 67 receives the command control of a flow control device 68. A pressure detector 62 is signal-connected to the flow control device 68, and pressure detection information in an introduction pipe 61 obtained by the pressure detector 62 is transmitted to the flow control device 68. The flow control device 68 controls the valve opening of the flow regulating valve 67, i.e., the gas feed flow regulating condition based on the pressure detection information obtained from the pressure detector 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention moves a gas transfer member in a pump chamber based on the rotation of a rotary shaft, and transfers gas by the operation of the gas transfer member to bring about a suction action.
The present invention relates to a gas supply device in a vacuum pump equipped with a gas supply device that supplies an inert gas to the gas existing region.

[0002]

2. Description of the Related Art In a vacuum pump disclosed in Japanese Unexamined Patent Publication No. 5-118286, a pair of rotors are rotated in a meshed state. The rotational movement of the rotors that rotate while meshing transfers the gas. In this pump, an inert gas such as nitrogen gas is supplied into the gas passage to dilute the gas containing the reaction product. Many of the reaction products tend to solidify when the pressure rises and the temperature drops, and the gas exhausted from a dry etching apparatus, which is a kind of semiconductor manufacturing apparatus, contains such substances. May have been. Even such a substance, when diluted with an inert gas, has a low solidifying temperature and is hard to solidify.

Japanese Unexamined Patent Publication (Kokai) No. 5-118286 discloses a structure in which a needle valve or a fixed throttle is interposed on the supply path of the inert gas. Needle valve
The supply flow rate of the inert gas can be adjusted. The supply flow rate of the inert gas in the apparatus using the fixed throttle is adjusted by selecting the fixed throttle having the required supply capacity.

[0004]

Securing a stable dilution effect by supplying an inert gas is important in solving the problem of gas solidification. However, with the method of always supplying a constant amount of the inert gas, it is not possible to obtain a proper dilution of the gas with the inert gas according to the amount of exhaust of the vacuum pump.

An object of the present invention is to ensure proper dilution of gas by supplying an inert gas.

[0006]

To this end, according to the present invention, the gas transfer member in the pump chamber is moved based on the rotation of the rotary shaft, and the gas is transferred by the operation of the gas transfer member to bring about a suction action. The present invention is directed to a vacuum pump provided with a gas supply device for supplying an inert gas to a region in which gas is present, and in the invention of claim 1, gas supply flow rate adjusting means for adjusting a supply flow rate of the inert gas, and transfer of the gas. A gas supply device comprising a transfer amount detecting means for detecting an amount and a control means for controlling a gas supply flow rate adjusting state in the gas supply flow rate adjusting means in accordance with the transfer amount detected by the transfer amount detecting means. did.

In order to ensure proper dilution of the gas, the feed flow rate of the inert gas is increased when the detected gas transfer amount is large, and the feed flow rate of the inert gas is decreased when the detected gas transfer amount is small. It is achieved by

According to the invention of claim 2, in claim 1,
The transfer amount detecting means is pressure detecting means for detecting the pressure in the region where the gas exists. The detected pressure is
Accurately reflects the amount of gas transferred.

According to the invention of claim 3, in claim 2,
The detection target area of the pressure detection means is upstream of the inert gas supply port in the gas existence area.
The gas existence region upstream of the supply port of the inert gas,
This is a region where no inert gas exists. Therefore, the gas existence region upstream of the inert gas supply port is appropriate as the detection target region of the pressure detection means in order to enhance the detection accuracy of the gas transfer amount.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the inert gas supply path includes a base pipe and a plurality of branch pipes, and a single gas supply is provided. The flow rate adjusting means is arranged in the base pipe upstream of the connecting portion between the base pipe and the plurality of branch pipes.

The base pipe upstream of the connecting portion between the base pipe and the plurality of branch pipes is optimal as the installation location of the single gas supply flow rate adjusting means.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment in which the present invention is embodied in a multistage roots pump will be described below with reference to FIGS.

As shown in FIG. 1, a multi-stage roots pump 11
A front housing 13 is joined to the front end of the rotor housing 12, and the closure 10 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 16A, 16B, 16C and 16D. As shown in FIG. 3, the cylinder block 15 is composed of a pair of block pieces 17 and 18, and each chamber forming wall 16A, 16B, 1
6C and 16D are composed of a pair of wall pieces 161 and 162. As shown in FIG. 1, the front housing 13 and the chamber forming wall 1
Space between 6A and adjacent chamber forming walls 16A, 16B, 1
The space between 6C and 16D and the space between the rear housing 14 and the chamber forming wall 16D are respectively the pump chamber 39,
40, 41, 42, 43.

A pair of rotating shafts 19, 20 are rotatably supported by the front housing 13 and the rear housing 14 via radial bearings 21, 21A, 22, 22A. Both rotary shafts 19 and 20 are arranged parallel to each other. The rotation shafts 19 and 20 are the chamber forming walls 16A and 16
A plurality of rotors 23, 24, 25, 26, 27 are integrally formed on the rotary shaft 19 passed through B, 16C, 16D, and the same number of rotors 28, 29, 3 are provided on the rotary shaft 20.
0, 31, 32 are integrally formed. Rotor 23-3
2 has the same shape and the same size when viewed in the directions of the axes 191 and 201 of the rotary shafts 19 and 20. Rotors 23, 24, 2
The thicknesses of 5, 26, 27 are made smaller in this order, and the thicknesses of the rotors 28, 29, 30, 31, 32 are made smaller in this order. The rotors 23 and 28 are housed in the pump chamber 39 while meshing with each other, and the rotors 24 and 29 are housed in the pump chamber 40 while meshing with each other. The rotors 25 and 30 are housed in the pump chamber 41 while meshing with each other, and the rotors 26 and 31 are housed in the pump chamber 42 while meshing with each other. The rotors 27 and 32 are housed in the pump chamber 43 while meshing with each other.

The rear housing 14 includes a gear housing 3
3 is assembled. The rotary shafts 19 and 20 penetrate the rear housing 14 and project into the gear housing 33, and the gears 34 and 3 are provided at the projecting ends of the rotary shafts 19 and 20, respectively.
5 are fixed to each other in a meshed state. Gear 34,
Reference numeral 35 scrapes up the lubricating oil (not shown) stored in the gear housing 33. Lubricating oil lifted up is gear 3
4, 35 and the radial bearings 21A, 22A are lubricated.

An electric motor M is attached to the gear housing 33. The driving force of the electric motor M is transmitted to the rotary shaft 19 via the shaft joint 63, and the rotary shaft 19 is driven by the rotary shaft 19 shown in FIG.
~ It is rotated in the direction of arrow R1 in FIG. The rotation of the rotary shaft 19 is transmitted to the rotary shaft 20 via the gears 34 and 35,
The rotating shaft 20 rotates in the direction opposite to the rotating shaft 19 as shown by an arrow R2 in FIGS.

An inverter 65 is electrically connected to the electric motor M. The inverter 65 controls the rotation speed of the electric motor M using the AC power source 66 as a power source based on the command control of the rotation control device 64.

As shown in FIGS. 1 and 3, the chamber forming wall 16
A passage 163 is formed in each of A, 16B, 16C and 16D. As shown in FIG. 3, the chamber forming walls 16A, 16
An inlet 164 and an outlet 165 of the passage 163 are formed in B, 16C and 16D. Adjacent pump rooms 39, 4
0, 41, 42, 43 communicate with each other through a passage 163.

As shown in FIG. 4, an inlet 181 is formed in the block piece 18 so as to communicate with the pump chamber 39. The introduction pipe 61 is connected to the introduction port 181.
A pressure detector 62 as a pressure detecting means is attached to the introduction pipe 61. The pressure detector 62 detects the pressure in the introduction pipe 61.

As shown in FIG. 5, the block piece 17 is formed with a discharge port 171 so as to communicate with the pump chamber 43. The gas introduced from the inlet 181 into the pump chamber 39 is transferred from the inlet 164 of the chamber forming wall 16A through the passage 163 to the adjacent pump chamber 40 from the outlet 165 by the rotation of the rotors 23 and 28. Hereinafter, in the same manner, the gas is supplied in the order of decreasing the volume of the pump chambers, that is, the pump chambers 40, 4
1, 42, 43 are transferred in this order. The gas transferred to the pump chamber 43 is discharged to the outside through the discharge port 171. The rotors 23 to 32 are gas transfer bodies that transfer gas.

As shown in FIGS. 1 and 3, the rotor housing 12 includes a plurality of fixed restrictors 36A, 36B, 36.
C and 36D are screwed. As shown in FIG. 1, a fixed throttle 37 is screwed into the front housing 13, and a fixed throttle 38 is screwed into the rear housing 14. Each fixed throttle device 36A, 36B, 36C, 36
D, 37, 38 include branch pipes 54, 55, 56, 57, 5
8 and 59 are connected, and branch pipes 54, 55, 56,
57, 58 and 59 are connected to the base pipe 60. Base tube 6
0 is connected to a gas supply source (not shown). The inert gas (for example, nitrogen gas) of the gas supply source is passed through the base pipe 60 and the branch pipes 54 to 59 to the fixed restrictors 36A and 36A.
B, 36C, 36D, 37, 38.

As shown in FIG. 2, the fixed restrictor 36A is
Check valve 44 and fixed throttle 45 screwed to check valve 44
And a pipe joint 46 screwed to the check valve 44.
The check valve 44 is upstream of the fixed throttle 45. Check valve 44
A seal ring 47 is interposed between the fixed diaphragm 45 and the fixed diaphragm 45. An orifice 451 is formed at the tip of the fixed diaphragm 45.

The check valve 44 includes a housing 51 having a valve hole 511, a guide 48 also serving as a spring seat, and a guide 48.
Valve support 49 which is slidably guided by the valve support 49
A ring-shaped rubber elastic valve 50 attached to the
And a spring 52 for urging the valve support 49 toward the valve hole 511. A passage groove 491 is formed in the valve support body 49. The branch pipe 54 is fitted in the check valve 44.

The pipe joint 46 is provided with a pair of rubber seal rings 53A and 53B. When the pipe joint 46 is tightened to the check valve 44, the seal ring 53A elastically deforms between the pipe joint 46 and the branch pipe 54, and
The seal ring 53B elastically deforms between the check valve 44 and the branch pipe 54. The branch pipe 54 includes seal rings 53A and 5A.
The elastic deformation of 3B prevents the fixed throttle device 36A from coming off.

Other fixed restrictors 36B, 36C, 36D,
37 and 38 also have the same structure as the fixed diaphragm 36A. The inert gas sent to the fixed restrictors 36A, 36B, 36C, 36D, 37, 38 pushes the elastic valve 50 against the spring force of the spring 52 and passes through the valve hole 511. Valve hole 511
The inert gas that has passed through passes through the passage groove 491 and enters the fixed throttle 45. The inert gas that has entered the fixed throttle 45 passes through the orifice 451.

As shown in FIG. 1, a passage 131 in the front housing 13 is connected to the fixed throttle 37. The passage 131 communicates with annular passages 132 and 133 formed on the peripheral surfaces of the shaft holes 134 and 135 of the front housing 13 through which the rotary shafts 19 and 20 pass. Fixed wringer 3
A passage 141 in the rear housing 14 is connected to the reference numeral 8. The passage 141 communicates with annular passages 142 and 143 formed on the peripheral surfaces of the shaft holes 144 and 145 of the rear housing 14 through which the rotary shafts 19 and 20 pass.

The inert gas sent to the fixed restrictor 36A via the base pipe 60 and the branch pipe 54 is sent to the passage 163 in the chamber forming wall 16A. The inert gas sent to the fixed restrictor 36B via the base pipe 60 and the branch pipe 55 is sent to the passage 163 in the chamber forming wall 16B. The inert gas sent to the fixed restrictor 36C via the base pipe 60 and the branch pipe 56 is sent to the passage 163 in the chamber forming wall 16C. Fixed throttle device 36D through the base pipe 60 and the branch pipe 57
The inert gas sent to the chamber is used for the passage 16 in the chamber forming wall 16D.
Sent to 3. The inert gas sent into each passage 163 dilutes the gas in each passage 163 [for example, a gas such as perfluorocarbon (PFC) gas].

The inert gas sent to the fixed restrictor 37 through the base pipe 60 and the branch pipe 58 receives the passages 131, 132,
It is sent to 133. The inert gas sent into the passages 132, 133 dilutes the gas that tries to enter the radial bearings 21, 22 through the gap between the peripheral surface of the rotary shafts 19, 20 and the shaft holes 134, 135 of the front housing 13. To do.

The inert gas sent to the fixed restrictor 38 via the base pipe 60 and the branch pipe 59 passes through the passages 141, 142,
It is sent to 143. The inert gas sent into the passages 142, 143 dilutes the gas that tries to enter the radial bearings 21A, 22A through the gap between the peripheral surface of the rotary shafts 19, 20 and the shaft holes 144, 145 of the rear housing 14. To do.

The supply pressure of the inert gas, that is, the pressure in the base pipe 60 and the branch pipes 54 to 59, is set to the chamber forming walls 16A and 16A.
It is set higher than the expected pressure in the passage 163 in B, 16C, 16D and the expected pressure in the passages 132, 133, 142, 143.

Connection part 5 between base pipe 60 and branch pipes 54 to 59
An electromagnetic flow rate adjusting valve 67 is attached to the base pipe 60 upstream of 41,551,561,571,581,591. The flow rate adjusting valve 67 is a gas supply flow rate adjusting means for adjusting the supply flow rate of the inert gas. The flow rate adjusting valve 67 adjusts the flow rate of the inert gas flowing through the base pipe 60.

The flow rate adjusting valve 67 is controlled by the flow rate control device 68. The flow rate control device 68 includes a pressure detector 62.
Is connected by a signal, and the pressure detection information obtained by the pressure detector 62 is sent to the flow rate control device 68. The flow rate control device 68 controls the valve opening degree of the flow rate adjusting valve 67, that is, the gas supply flow rate adjusting state based on the pressure detection information obtained from the pressure detector 62. In the present embodiment, the flow rate control device 68 controls the valve opening degree of the flow rate adjusting valve 67 so that the dilution degree of the gas becomes a desired dilution degree. When the pressure detected by the pressure detector 62 increases, that is, when the gas transfer amount increases, the flow rate control device 68 issues a command to increase the valve opening degree of the flow rate adjusting valve 67. The flow rate adjusting valve 67 increases the valve opening degree based on a valve opening degree increasing command from the flow rate control device 68,
The supply flow rate of the inert gas flowing through the base pipe 60 increases. When the pressure detected by the pressure detector 62 decreases, the flow rate control device 68 issues a command to decrease the valve opening degree of the flow rate adjusting valve 67. The flow rate adjusting valve 67 reduces the valve opening degree based on the valve opening degree reduction command from the flow rate control device 68, and the supply flow rate of the inert gas flowing through the base pipe 60 decreases.

The pressure detector 62 is a transfer amount detecting means for detecting the transfer amount of gas. The flow rate control device 68 is a control unit that controls the valve opening degree (that is, the gas supply flow rate adjustment state) of the flow rate adjusting valve 67 according to the pressure (that is, the transfer amount) detected by the transfer amount detection unit.

The following effects can be obtained in the first embodiment. (1-1) If the supply flow rate of the inert gas is small when the gas transfer rate is large, the reaction products contained in the gas may solidify,
If the supply flow rate of the inert gas is large when the gas transfer amount is small, the suction action of the vacuum pump is reduced.

When the pressure in the introduction pipe 61 detected by the pressure detector 62 is high, that is, when the gas transfer amount is large, the flow rate control device 68 increases the supply flow rate of the inert gas to dilute the gas. To the desired dilution. When the pressure in the introduction pipe 61 detected by the pressure detector 62 is low, that is, when the gas transfer amount is small, the flow rate control device 68 reduces the supply flow rate of the inert gas to obtain a desired gas dilution degree. Bring to dilution. The configuration in which the supply flow rate of the inert gas is adjusted according to the transfer amount of the gas makes it possible to ensure proper dilution of the gas.

(1-2) The pressure in the introduction pipe 61 accurately reflects the amount of gas transferred. Therefore, the pressure detected by the pressure detector 62 accurately reflects the gas transfer amount, and the appropriate supply flow rate of the inert gas can be adjusted according to the gas transfer amount.

(1-3) Fixed throttle 36A, 36B, 36
The orifices 451 of C and 36D correspond to the chamber forming walls 16A and 1A.
The passage 163 in 6B, 16C, 16 serves as a supply port for the inert gas to the gas existing region. The orifice 451 of the fixed restrictor 37 serves as a supply port of the inert gas to the passage 131 that communicates with a gas existence region, which is a gap between the peripheral surfaces of the rotary shafts 19 and 20 and the shaft holes 134 and 135 of the front housing 13. . Orifice 45 of fixed restrictor 38
Reference numeral 1 serves as an inert gas supply port to a gas existing region, which is a gap between the peripheral surfaces of the rotary shafts 19 and 20 and the shaft holes 144 and 145 of the rear housing 14. Each fixed aperture 36
The gas transfer paths upstream of the orifices 451 of the A, 36B, 36C, 36D, 37, and 38 are regions where no inert gas exists. Therefore, each fixed throttle 36A, 36
The inside of the introduction pipe 61, which is a part of the gas transfer path upstream of the orifices 451 of the B, 36C, 36D, 37, and 38, is used to improve the detection accuracy of the gas transfer amount.
2 is appropriate as the detection target area.

(1-4) Each chamber forming wall 16A, 16B, 16
Pressure in the passage 163 in C, 16D, passages 132, 13
3 and the pressures in the passages 142 and 143 are different. Therefore, each chamber forming wall 16A, 16B, 16
Concentration of gas in passage 163 in C, 16D, passage 13
The concentration of the gas in 2, 133 and the concentration of the gas in the passages 142, 143 are different from each other. Therefore, each chamber forming wall 16
Passages 163 and 13 in A, 16B, 16C and 16D
The proper supply flow rates of the inert gas per unit time with respect to the gas existing regions of the gas channels 2, 133 and the passages 142, 143 are also different. Fixed throttle 36A, 36B, 36
C, 36D, 37, and 38 are selected so as to provide a proper supply flow rate of the inert gas per unit time to the above-mentioned existence region so as to obtain a desired dilution degree in the above-mentioned existence region. That is, the fixed restrictors 36A, 36
Orifice 4 at B, 36C, 36D, 37, 38
The diameter D of 51 (shown in FIG. 2) is set so as to provide the appropriate supply flow rate in consideration of the pressure in the supply paths of the branch pipes 54 to 59 and the base pipe 60, the pressure in the existing region, and the like. ing.

Such fixed aperture devices 36A to 36D, 3
In the present embodiment using 7, 38, the flow rate adjusting valve 67
Is a connecting portion 54 between the base pipe 60 and the plurality of branch pipes 54 to 59.
The supply flow rate of the inert gas is adjusted in the base pipe 60 upstream of 1 to 591. That is, the connection parts 541 to 59
Adjustment of the supply flow rate of the inert gas in the base pipe 60 upstream of 1 is performed by each fixed throttle device 36A to 36D, 37, 38.
It is possible to adjust the degree of dilution of the gas in the gas transfer path downstream of the orifice 451. Therefore, the supply path of the inert gas upstream of the connecting portions 541 to 591 of the base pipe 60 and the plurality of branch pipes 54 to 59 is optimal as the installation location of the single flow rate adjusting valve 67.

(1-5) Fixed aperture devices 36A, 36B, 3
The setting of the diameter D of the orifice 451 that provides a predetermined gas supply flow rate in 6C, 36D, 37, and 38 can be easily calculated if the gas supply pressure and the pressure in the existing region are known. Therefore, the fixed restrictors 36A, 36B, 36C, 36D, 37, 38 that provide a predetermined gas supply flow rate are easy to manufacture, and the selection of the fixed restrictor that provides the gas supply flow rate required for the existing region is simple. .

(1-6) The multi-stage roots pump 11 includes a plurality of existing regions (that is, the passages 163 in the chamber forming walls 16A, 16B, 16C, 16D, and the annular passages) having different required supply flow rates of the inert gas. 132, 133, 142, 14
3). Such a multi-stage roots pump 11 has fixed restrictors 36A, 36B, 36C, 36D, 37, which provide appropriate gas supply flow rates according to respective existing regions where branch pipes 54 to 59, which are a plurality of supply paths, are connected. 38
Is suitable as an application target of the invention of the present embodiment in which the intervening pipes are selected and placed on the branch pipes 54 to 59.

Next, a second embodiment shown in FIG. 6 will be described. The same symbols are used for the same components as those in the first embodiment. A flow rate control device 68A is signal-connected to the inverter 65. The flow rate control device 68A is the inverter 6
The value of the current output from 5 to the electric motor M is detected.
The flow rate control device 68A controls the valve opening degree of the flow rate adjusting valve 67, that is, the gas supply flow rate adjusting state based on the detected current value. The detected current value reflects the load torque of the vacuum pump on the electric motor M, and this load torque is
It reflects the amount of gas transferred. The detected current value increases as the gas transfer amount increases, and the detected current value decreases as the gas transfer amount decreases.

In this embodiment, the flow rate control device 68A is used.
Controls the valve opening degree of the flow rate adjusting valve 67 so that the dilution degree of the gas becomes a desired dilution degree. When the detected current value increases, the flow rate control device 68A issues a command to increase the valve opening degree of the flow rate adjusting valve 67. The flow rate adjusting valve 67 increases the valve opening degree based on the valve opening degree increasing command from the flow rate control device 68A, and the supply flow rate of the inert gas flowing through the base pipe 60 increases.
When the detected current value decreases, the flow control device 68A
It issues a command to decrease the valve opening of the flow rate adjusting valve 67. The flow rate adjusting valve 67 reduces the valve opening degree based on the valve opening degree reduction command from the flow rate control device 68A, and the supply flow rate of the inert gas flowing through the base pipe 60 decreases.

In the second embodiment, the same effects as the items (1-1), (1-3) and (1-4) in the first embodiment can be obtained. Further, the pressure detector is not necessary, and the effect of cost reduction can be obtained.

The following embodiments are possible in the present invention. (1) The flow rate detector directly detects the gas transfer amount in the introduction pipe 61. (2) The inside of the passage 163 in the chamber forming walls 16A to 16D is set as the detection target area of the pressure detector 62.

(3) Use of a mechanical flow rate control valve equipped with a pressure sensitive mechanism as a gas supply flow rate adjusting means. This pressure-sensitive mechanism has, for example, the inside of the introduction pipe 61 as a detection target region, and the valve opening degree of the flow control valve is mechanically adjusted according to the pressure-sensitive state of the pressure-sensitive mechanism.

(4) In the first embodiment, the orifice 4 in the fixed restrictors 36A to 36D, 37 and 38.
The diameters of 51 are the same, and the flow rate adjusting valves 67 are provided in the respective branch pipes 54 to 59.

(5) Applying the present invention to a vacuum pump other than the roots pump. Inventions other than those described in the claims that can be grasped from the above-described embodiment will be described below.

[1] Any one of claims 1 to 4
Item 3. A gas supply device in a vacuum pump, wherein a fixed restrictor having a backflow prevention function is provided on the inert gas supply path.

[2] In the above item [1], there are a plurality of the supply paths, and a fixed restrictor for providing an appropriate gas supply flow rate per unit time according to each existing region connecting the plurality of the supply paths. And a gas supply device in a vacuum pump that is selected and interposed on the plurality of supply paths.

In this case, the plurality of branch pipes 54 to 59 in the first and second embodiments serve as a plurality of supply paths. [3] In any one of [1] to [4], [1], and [2], the vacuum pump is
A pump chamber in which a plurality of rotating shafts are arranged in parallel, rotors are arranged on the respective rotating shafts, rotors on adjacent rotating shafts are meshed with each other, and a plurality of rotors in a meshed state are accommodated as one set. A gas supply device for a vacuum pump, which is a multi-stage roots pump formed in a housing so as to be arranged in the axial direction of the rotary shaft.

[0052]

As described above in detail, in the present invention, the gas supply flow rate adjusting state in the gas supply flow rate adjusting means is controlled according to the gas transfer rate detected by the transfer rate detecting means, so that it is inactive. The excellent effect that a stable dilution effect due to gas supply can be ensured is exhibited.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a first embodiment.

FIG. 2 is a sectional view of a fixed aperture device.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB of FIG.

5 is a sectional view taken along line CC of FIG.

FIG. 6 is a plan sectional view showing a second embodiment.

[Explanation of symbols]

11 ... Multi-stage roots pump. 132, 133, 142, 1
43, 163 ... A passage that becomes an existing area. 19, 20 ... Rotating axis. 23-32 ... A rotor serving as a gas transfer body. 39-43
…pump room. 451 ... An orifice serving as a supply port. 54,
55, 56, 57, 58, 59 ... Branch pipes. 541,55
1,561,571,581,591 ... Connection part. 60 ...
Base tube. 62 ... A pressure detector as a transfer amount detecting means. 67
... A flow rate adjusting valve as a gas supply flow rate adjusting means. 68,6
8A ... A flow rate control device as a control means.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Ishigure             2-1, Toyota-cho, Kariya City, Aichi Stock Association             Inside Toyota Toyota Industries F-term (reference) 3H029 AA06 AA09 AA18 AB06 BB42                       BB51 CC02 CC09 CC24 CC26                       CC54 CC55 CC83                 3H045 AA05 AA09 AA15 AA25 AA38                       BA19 CA03 DA12 EA13 EA14                       EA26 EA34 EA45                 3H076 AA16 AA21 AA38 BB21 BB33                       CC07 CC41 CC84 CC94 CC97

Claims (4)

[Claims] 1. A gas transfer body in a pump chamber is moved based on the rotation of a rotating shaft, the gas is transferred by the operation of the gas transfer body to bring about a suction action, and an inert gas is supplied to a region where the gas exists. In a vacuum pump provided with a gas supply device, a gas supply flow rate adjusting means for adjusting a supply flow rate of the inert gas, a transfer amount detecting means for detecting a transfer amount of the gas, and a transfer amount detecting means. A gas supply device in a vacuum pump, comprising: a control unit that controls a gas supply flow rate adjustment state in the gas supply flow rate adjustment unit according to a transfer amount. 2. The transfer amount detecting means is pressure detecting means for detecting the pressure in the region where the gas exists.
A gas supply device in the vacuum pump according to. 3. The gas supply device for a vacuum pump according to claim 2, wherein the detection target area of the pressure detection means is located upstream of the inert gas supply port in the gas existing area. 4. The supply path for the inert gas comprises a base pipe and a plurality of branch pipes, and the single gas supply flow rate adjusting means is more than a connecting portion between the base pipe and the plurality of branch pipes. The gas supply device in the vacuum pump according to any one of claims 1 to 3, which is disposed in the base pipe upstream.