JP2010138741A - Vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pump reducing harmful influence of product as much as possible on the assumption of use of technology adjusting exhaust performances of the vacuum pump by returning part of gas to an upstream side from a downstream side of the vacuum pump. <P>SOLUTION: A reverse flow path inlet 52 of a reverse flow path 50 is disposed at a compression step 204, and a reverse flow path outlet 54 is disposed at an exhaust step 202. At least one step fixed blade 40 or rotary blade 32 exists at an exhaust port 90 side of the reverse flow path inlet 52. Position of the reverse flow path outlet 54 of the reverse flow path 50 is at a position where at least one step rotary blade 32 or fixed blade 40 exists at a suction port 10 side. In other words, the reverse flow path outlet 54 is installed at a downstream (exhaust port 90 side) of at least one step rotary blade 32 or fixed blade 40. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vacuum pump such as a turbo molecular pump that performs exhaust processing of a vacuum vessel such as a process chamber used in a semiconductor manufacturing apparatus.

In a vacuum pump such as a turbo molecular pump, it is required to appropriately control the pressure in the exhaust chamber according to various work conditions. As a method of controlling the pressure in the exhaust chamber, a method of controlling the performance of the pump itself by using a pressure regulating valve for regulating the pressure or changing the rotation speed of the pump itself has been used. Among these, in the method using the pressure regulating valve, the pressure regulating valve itself is expensive, and there is a problem that the cost is increased. Further, in the method of changing the rotation speed of the pump, a separate control mechanism for appropriately changing the rotation speed is required, and this also increases the cost.
Therefore, a method of returning a part of the gas exhausted by the vacuum pump to the intake port side, which is a technique described in Patent Document 1 below, has been proposed. In this method, a part of the gas to be exhausted is returned from the downstream side to the upstream side of the vacuum pump, so that a larger amount of gas can be sucked in the vacuum pump. Thereby, the compression performance of a vacuum pump will be reduced. Therefore, by adjusting the amount of gas returned to the upstream side of the vacuum pump, the exhaust performance of the vacuum pump can be adjusted as a result.
JP2005-140079

By the way, in the vacuum pump, it was inevitable that floating substances called particles contained in the exhaust gas adhere to the inside of the pump as products (deposits). There was a problem that the performance of the pump deteriorated due to this product, or contact with the rotor blades might occur. Furthermore, in order to remove the attached product, it was necessary to disassemble the apparatus once and carefully wash it.
Here, the relationship between the pressure at which the gas solidifies and the temperature will be described with reference to the vapor pressure curve diagram of FIG. In this figure, the left side of the curve, that is, the side where the temperature is low, indicates that the solid is solid, and when the pressure is high, it is solidified even at high temperature. For example, in the case of aluminum chloride, it solidifies at about 50 ° C. when the pressure is 1 pascal (pa), whereas it solidifies at about 95 ° C. when the pressure is 100 (pa).

Therefore, conventionally, in order to avoid particles adhering to the regulating valve and the filter, a method has been proposed in which a heater is provided to increase the temperature and prevent the gas from solidifying. However, the gas that has not been solidified by the adjusting valve or the filter by the heater is cooled by the casing, and as a result, the product accumulates in the casing. Since the gas in the vicinity of the discharge port of the turbo molecular pump has a high pressure, particles are deposited as a product even at a high temperature.
Therefore, the object of the present invention is to return the gas from the downstream side to the upstream side of the vacuum pump, and on the premise of the technology for adjusting the exhaust performance of the vacuum pump, a vacuum that can prevent the product from being attached as much as possible. Is to provide a pump.

In the invention of claim 1, on a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotary blades attached to the rotating body, The fixed blades alternately arranged with these rotary blades, the fixed blade spacer that holds the fixed blades at a fixed position, and the disk-shaped base are connected, and the rotating body, the motor, the rotary blades, the fixed blades, and In a vacuum pump comprising a cylindrical casing covering a fixed blade spacer, and rotating the rotating body by the motor to perform exhaust from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade. The object is achieved by providing a reverse flow path in which a part of the gas on the exhaust port side flows back to the intake port side and heating means for heating the casing.
In the invention of claim 2, on the disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotary blades attached to the rotating body, The fixed blades alternately arranged with these rotary blades, the fixed blade spacer that holds the fixed blades at a fixed position, and the disk-shaped base are connected, and the rotating body, the motor, the rotary blades, the fixed blades, and In a vacuum pump comprising a cylindrical casing covering a fixed blade spacer, and rotating the rotating body by the motor to perform exhaust from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade. A part of the gas on the exhaust port side is provided with a backflow path in which the gas flows back to the intake port side;
The outlet of the backflow path is provided at a plurality of locations where the backflow path is branched, and at least a pair of the outlets are arranged at positions facing each other across the rotating shaft of the rotating body, or the outlet is regular. The object is achieved by being arranged at the position of the apex of the square.

In the invention of claim 3, on a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotary blades attached to the rotating body, The fixed blades alternately arranged with these rotary blades, the fixed blade spacer that holds the fixed blades at a fixed position, and the disk-shaped base are connected, and the rotating body, the motor, the rotary blades, the fixed blades, and In a vacuum pump comprising a cylindrical casing covering a fixed blade spacer, and rotating the rotating body by the motor to perform exhaust from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade. Provided with a reverse flow path in which a part of the gas on the exhaust port side flows back to the intake port side, and provided with an inlet of the reverse flow path at the blade exhaust part where the rotary blade and the fixed blade are arranged in a plurality of stages Said To achieve the target.
In the invention according to claim 4, on the disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotating blades attached to the rotating body, The fixed blades alternately arranged with these rotary blades, the fixed blade spacer that holds the fixed blades at a fixed position, and the disk-shaped base are connected, and the rotating body, the motor, the rotary blades, the fixed blades, and In a vacuum pump comprising a cylindrical casing covering a fixed blade spacer, and rotating the rotating body by the motor to perform exhaust from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade. Provided with a reverse flow path in which a part of the gas on the exhaust port side flows back to the intake port side, and provided with an outlet of the reverse flow path at the blade exhaust part where the rotary blade and the fixed blade are arranged in a plurality of stages Said To achieve the target.
In the invention of claim 5, on a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotating blades attached to the rotating body, The fixed blades alternately arranged with these rotary blades, the fixed blade spacer that holds the fixed blades at a fixed position, and the disk-shaped base are connected, and the rotating body, the motor, the rotary blades, the fixed blades, and In a vacuum pump comprising a cylindrical casing covering a fixed blade spacer, and rotating the rotating body by the motor to perform exhaust from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade. Provided with a reverse flow path in which a part of the gas on the exhaust port side flows back to the intake port side, and at the blade exhaust part where the rotary blade and the fixed blade are arranged in a plurality of stages, the inlet and the outlet of the reverse flow path By providing , To achieve the above purpose.
According to a sixth aspect of the present invention, in the third or fifth aspect of the present invention, at least one stage of fixed blades or rotor blades is disposed on the exhaust port side from the position where the inlet of the backflow path is provided. It is characterized by that.
According to a seventh aspect of the present invention, in the fourth or fifth aspect of the present invention, at least one stage of fixed blades or rotor blades is disposed on the inlet side from the position where the outlet of the backflow path is provided. It is characterized by.

In the invention according to claim 8, in the invention according to any one of claims 3 to 7, the outlet of the backflow path is provided at a plurality of locations by branching the backflow path, and at least a pair of the outlets. Are arranged at positions facing each other across the rotation axis of the rotating body, or the outlet is arranged at a vertex of a regular polygon.
According to a ninth aspect of the present invention, in the second or eighth aspect of the invention, the flow rate of the gas passing through the backflow path is adjusted between the inlet of the backflow path and the position where the backflow path is branched. A control valve is provided.
According to a tenth aspect of the present invention, in the invention according to any one of the third to ninth aspects, the casing provided with the outlet of the backflow path and the fixed blade spacer or the fixed blade rim. A seal member for separating the gas path and the gap is provided so that the gas does not leak into the gap.
The invention according to claim 11 is characterized in that, in the invention according to claim 10, the seal member is provided in two upper and lower stages inside the entire circumference of the casing.
The invention according to claim 12 is the invention according to claim 10 or 11, wherein the seal member is an O-ring.
According to a thirteenth aspect of the present invention, in the invention according to the tenth or eleventh aspect, the seal member is a protrusion provided on the fixed wing spacer or the rim of the fixed wing.
The invention according to claim 14 is characterized in that, in the invention according to claim 13, the height of the protrusion of the protrusion becomes smaller as the position is closer to the air inlet.
According to a fifteenth aspect of the present invention, in the invention according to the tenth or eleventh aspect, the seal member is a protrusion provided on an inner peripheral surface of the casing.
The invention according to claim 16 is characterized in that, in the invention according to claim 15, the protrusion height of the protrusion portion becomes smaller as the position is closer to the exhaust port.
The invention according to claim 17 is the invention according to any one of claims 1 to 16, further comprising a rotation speed control means for controlling the rotation speed of the rotor blade.

  According to the present invention, the product accumulated in the passage through which the gas from the exhaust port passes can be reduced, so that the exhaust performance of the vacuum pump can be stabilized, and the pressure adjusting valve for adjusting the pressure is provided. It is possible to easily adjust the pressure of the exhausted chamber without using it.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a longitudinal sectional view showing the configuration of the vacuum pump according to the first embodiment. The vacuum pump 100 is installed in a cylindrical casing 20 alternately with an inlet 10 for sucking gas from a chamber (not shown), a plurality of rotor blades 32 provided on the rotating body 30, and the rotor blades 32. The fixed wing 40, a disk-shaped base 70 that covers the lower portion of the casing 20, a screw groove 80 that exhausts air by a drag action, and an exhaust port 90 that exhausts air to the outside.
The rotating body 30 is supported and controlled in a non-contact manner by being magnetically levitated by the radial bearings 34 and 36 and the thrust bearing 38.
The rotating body 30 is rotationally driven at a high speed by a driving motor 60. As the rotating body 30 rotates at a high speed, the plurality of rotor blades 32 provided for the rotation also rotate at the same time, and exhaust is performed by interaction with the plurality of stationary blades 40 arranged alternately. ing.

The vacuum pump 100 according to this embodiment is provided with a backflow path 50 that backflows part of the exhausted gas to the intake port 10 side. The backflow path 50 includes a backflow path inlet 52 that sucks in exhausted gas and a backflow path outlet 54 that discharges gas, and an adjustment valve 56 that adjusts the amount of gas flowing through the backflow path 50 is provided in the middle. Yes.
By providing the backflow path 50, a part of the exhausted gas can be returned from the downstream side to the upstream side of the vacuum pump, and a larger amount of gas can be sucked in the vacuum pump. . Therefore, the compression performance of the vacuum pump can be reduced. As a result, the exhaust performance of the vacuum pump can be adjusted by adjusting the amount of gas returned to the upstream side of the vacuum pump 100 by the adjusting valve 56.

In the first embodiment, a ring-shaped heater 110 for heating the casing 20 is provided around the casing 20.
It is conceivable that the gas that has flowed back through the backflow path 50 contains a component that may become a product. When the gas flows backward, the placed state changes (pressure increase or temperature decrease), so that the gas may solidify and become a product and adhere. Therefore, heating by the heater 110 reduces gas solidification.
In this figure, the casing 20 is heated. However, the present invention is not limited to this. For example, the backflow path 50 itself may be heated. That is, a place where the product easily adheres is selected, and a heater 110 is provided there for heating.
It is important to set the heating temperature to such a level that no product is deposited.

Next, a second embodiment will be described with reference to FIG.
First, as shown in FIG. 2, if a portion where the rotor blades 32 and the stationary blades 40 alternately installed with the rotor blades 32 are installed is a blade exhaust part 200, the upstream part is the exhaust stage 202, the downstream part. The compression stage 204.
In this embodiment, the backflow path inlet 52 of the backflow path 50 is provided in the compression stage 204, and the backflow path outlet 54 is provided in the exhaust stage 202.
When the backflow path inlet is provided in the thread groove portion as in the invention described in Patent Document 1, as a result, a gas containing a component that may become a product may be backflowed. If the backflow path inlet 52 and the backflow path outlet 54 are provided in the blade exhaust part 200 as in this embodiment, the pressure is not so high, so there is a low possibility that the gas will solidify. However, product deposition can be reduced.
On the other hand, in consideration of adjusting the exhaust performance of the vacuum pump, it is desirable that the pressure difference between the backflow path inlet 52 and the backflow path outlet 54 is large. The route outlet 54 is installed in the upstream direction.
However, in order to prevent particles generated in the thread groove 80 from flowing back to the intake port 10 side, at least one stage of the rotary blade 32 or the fixed blade 40 exists on the exhaust port 90 side from the reverse flow path inlet 52. It is desirable. By doing this, it is possible to reduce the circulation of the inside of the blade exhaust part 200 due to particles entering from the backflow path inlet 52 by the one-stage rotary blade 32 or the fixed blade 40 serving as a lid.
In this type of vacuum pump, a total of 8 to 10 rotary blades 32 and fixed blades 40 are generally provided.

In this embodiment, the position of the reverse flow path outlet 54 of the reverse flow path 50 is a position where at least one stage of the rotary blade 32 or the fixed blade 40 exists on the intake port 10 side. In other words, the backflow path outlet 54 is installed downstream (exhaust port 90 side) from at least one stage of the rotary blade 32 or the fixed blade 40.
By doing so, since the rotor blade 32 or the fixed blade 40 is on the intake port side from the backflow path outlet 54, even if particles are mixed in the gas coming from the exhaust port 90 side, this can return to the exhausted chamber. Can be lowered.

Subsequently, a third embodiment will be described with reference to FIG.
In this embodiment, the base 70 covers the compression stage 204 of the blade exhaust part 200 from below. In other words, the connecting portion 300 between the casing 20 and the base 70 is provided above the compression stage 204. For this reason, since the backflow path inlet 52 of the backflow path 50 is provided in the compression stage 204, the backflow path 50 inevitably passes through the base 70.
Normally, in this type of vacuum pump, the casing 20 is made of stainless steel and the base 70 is made of aluminum, and the base is formed thicker. If the backflow path inlet 52 of the backflow path 50 is formed in the casing 20, the strength of the casing 20 may be reduced. By providing a lower passage with a higher energy load in the base 70 as in this embodiment, the strength is increased. Can be reduced.

Next, a fourth embodiment will be described with reference to FIGS.
In the second and third embodiments, the backflow path outlet 54 of the backflow path 50 is provided in the fixed blade spacer 42 located in the exhaust stage 202.
In this embodiment, as shown in the sectional view of the fixed blade spacer 42 of FIG. 4, a plurality of backflow path outlets 54 are provided at the same height.
If only one backflow path outlet 54 is provided, gas will hit the rotor blade 32 from one direction, and the rotor 30 may be shaken, making it difficult to control the rotor 30. This is because the rotator 30 is magnetically levitated and rotates at a high speed, so that it is affected by a slight force. Therefore, a plurality of backflow path outlets 54 are provided around the rotator 30 so that the gas uniformly strikes the rotator 30 to reduce the shake of the rotator 30.
The position where the reverse flow path outlet 54 is provided is a position where force is evenly applied to the center of the rotating body 30. For example, when two backflow path outlets 54 are provided, as shown in FIG. 4 (1), they are arranged at positions that are symmetrical with respect to the center. When three or more places are provided, they are arranged at the vertices of inscribed regular polygons. For example, when three places are provided, they are provided at positions corresponding to the apexes of the inscribed regular triangle as shown in FIG.

As shown in FIG. 5, the reverse flow path 50 branches after passing through the control valve 56. It is not necessary to provide the control valve 56 in each passage, and it is sufficient to provide one place before branching.
Note that the shake of the rotating body 30 can be reduced by providing a plurality of backflow path inlets 52 of the backflow path 50 so that the influence of the gas sucked on the rotating body 30 is evenly distributed. In this case, the position where the backflow path inlet 52 is provided is a position that equally affects the center of the rotating body 30, similarly to the backflow path outlet 54 described above. When two places are provided, the positions are symmetrical with respect to the center, and when three or more places are provided, they are arranged at the vertices of the inscribed regular polygon.

Next, a fifth embodiment will be described with reference to FIGS.
In this embodiment, the seal member is provided between the casing 20 and the member (the fixed blade spacer 42 or the fixed blade rim) in which the reverse flow path outlet 54 of the reverse flow path 50 is formed. There is inevitably a small gap necessary for assembling the vacuum pump between the casing 20 and the fixed blade spacer 42 or the fixed blade rim. This is because, when the casing 20 is covered at the end of the assembling work, if there is no gap at all, the casing 20 cannot be effectively inserted.
However, on the other hand, if there is a large amount of gas passing through the gap and passing through the backflow path outlet 54 toward the exhaust port 90, the ability to adjust the exhaust performance of the vacuum pump may be adversely affected. Therefore, in this embodiment, a seal member is provided in the vicinity of the backflow path outlet 54 in order to reduce the gas that flows out to the exhaust port 90 side. The seal member functions to isolate the gas path and the gap.

The seal member used in this embodiment is a projection provided on the O-ring 310 shown in FIGS. 6 (1) and 7 (1) and the fixed blade spacer 42 shown in FIGS. 6 (2) and 7 (2). 320 or a protrusion 322 provided inside the casing 20 separately from the fixed blade spacer 42 shown in FIGS. 6 (3) and 7 (3). FIG. 6 is a longitudinal sectional view of the vicinity of the backflow path outlet 54 provided with a seal member, and FIG. 7 is a plan view thereof.
In this way, by providing the O-ring 310 or the protrusions 320 and 322, the gas flowing out to the exhaust port 90 side can be reduced.
These sealing members may be circular so as to concentrically surround the backflow path outlet 54, that is, the hole opened in the casing 20 and the hole opened in the fixed blade spacer 42, or the entire gap may be installed. You may install in two steps up and down in the shape of a ring over the circumference. If the seal member is set over the entire circumference, there is an advantage that only one hole is required to be opened in the casing 20.
When the projecting portion 320 or the projecting portion 322 is provided as the seal member, it is convenient if the surface on the intake port 10 side, the surface on the exhaust port 90 side, or both surfaces are inclined. This is because, in the assembling process of the vacuum pump 100, when the casing 20 is finally fitted, the inclined portion reduces the catch.

In the above-described embodiment, the case where the backflow path outlet 54 is formed in the fixed blade spacer 42 has been described as an example. However, the outer peripheral surface of the rim of the fixed blade is in the gap between the casing 20 and the fixed blade spacer 42. It may be configured to be exposed, and the backflow path outlet 54 may be formed in the rim of the fixed wing.
In this case, the arrangement position of the O-ring is changed between the casing 20 and the rim of the fixed wing, and the formation position of the protrusion of the fixed wing spacer 42 is changed to the outer periphery of the rim of the fixed wing.
Two O-rings or two protrusions may be arranged or formed one by one on the fixed blade spacer 42 that sandwiches the rim of the fixed blade.
Here, the rim of the fixed wing refers to a ring-shaped member that constitutes a part of the fixed wing and holds the wing portion, and also functions to match the height position and the center position of the fixed wing. Some fixed wings are provided with a rim of the fixed wing only on the inner peripheral side.

  The embodiment described here is based on the technique of adjusting the exhaust performance of the vacuum pump by returning the gas from the downstream side to the upstream side of the vacuum pump. However, the control for changing the rotation speed of the vacuum pump 100 is also possible. In combination, the exhaust performance can also be adjusted. As described above, by performing the control for changing the rotation speed in addition to the method for returning the gas, the responsiveness of the pressure adjustment can be further improved.

It is the longitudinal cross-sectional view which showed the structure of the vacuum pump which concerns on a 1st Example. It is the longitudinal cross-sectional view which showed the structure of the vacuum pump which concerns on a 2nd Example. It is the longitudinal cross-sectional view which showed the structure of the vacuum pump which concerns on a 3rd Example. It is a figure for demonstrating the example which provided the backflow path exit which concerns on a 4th Example in two places (1) and three places (2). It is a figure for demonstrating the relationship between the backflow path | route exit and control valve which concerns on a 4th Example. It is a longitudinal cross-section for demonstrating the example which provided the sealing member (1) O-ring and (2) (3) protrusion part in the backflow path | route exit which concerns on 5th Example. It is a plane surface for demonstrating the example which provided the sealing member (1) O-ring and (2) (3) protrusion part in the backflow path | route exit which concerns on a 5th Example. It is the figure which showed the vapor pressure curve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Intake port 20 Casing 30 Rotating body 32 Rotary blade 34, 36 Radial bearing 38 Thrust bearing 40 Fixed blade 42 Fixed blade spacer 50 Backflow path 52 Backflow path inlet 54 Backflow path outlet 56 Control valve 60 Driving motor 70 Base 80 Screw groove 90 Exhaust port 100 Vacuum pump 110 Heater 200 Blade exhaust part 202 Exhaust stage 204 Compression stage 300 Connection part 310 O-ring 320 Projection part 322 Projection part

Claims (17)

On a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotating blades attached to the rotating body, and these rotating blades are alternately arranged. A fixed wing, a fixed wing spacer that holds the fixed wing in a fixed position, and a cylindrical base that is connected to the disk-shaped base and covers the rotating body, the motor, the rotating wing, the fixed wing, and the fixed wing spacer. A casing, and
In the vacuum pump that exhausts from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade by rotating the rotating body by the motor,
A vacuum pump comprising a reverse flow path through which part of the gas on the exhaust port side flows back to the intake port side, and heating means for heating the casing. A rotating body that is levitated and held by a magnetic bearing on a disk-shaped base;
A motor for rotating the rotating body, a plurality of rotating blades attached to the rotating body, fixed blades arranged alternately with these rotating blades, and a fixed blade that holds the fixed blade at a fixed position A cylindrical casing connected to the spacer and the disc-shaped base, and covering the rotating body, the motor, the rotating blade, the fixed blade, and the fixed blade spacer;
In the vacuum pump that exhausts from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade by rotating the rotating body by the motor,
A part of the gas on the exhaust port side is provided with a backflow path in which the gas flows back to the intake port side;
The outlet of the backflow path is provided at a plurality of locations where the backflow path is branched, and at least a pair of the outlets are arranged at positions facing each other across the rotating shaft of the rotating body, or the outlet is regular. A vacuum pump characterized by being arranged at the apex of a square. On a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotating blades attached to the rotating body, and these rotating blades are alternately arranged. A fixed wing, a fixed wing spacer that holds the fixed wing in a fixed position, and a cylindrical base that is connected to the disk-shaped base and covers the rotating body, the motor, the rotating wing, the fixed wing, and the fixed wing spacer. A casing, and
In the vacuum pump that exhausts from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade by rotating the rotating body by the motor,
A part of the gas on the exhaust port side is provided with a backflow path in which the gas flows back to the intake port side;
A vacuum pump characterized in that an inlet of the reverse flow path is provided in a blade exhaust portion where the rotary blade and the fixed blade are arranged in a plurality of stages. On a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotating blades attached to the rotating body, and these rotating blades are alternately arranged. A fixed wing, a fixed wing spacer that holds the fixed wing in a fixed position, and a cylindrical base that is connected to the disk-shaped base and covers the rotating body, the motor, the rotating wing, the fixed wing, and the fixed wing spacer. A casing, and
In the vacuum pump that exhausts from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade by rotating the rotating body by the motor,
A part of the gas on the exhaust port side is provided with a backflow path in which the gas flows back to the intake port side;
A vacuum pump characterized in that an outlet of the reverse flow path is provided in a blade exhaust portion where the rotary blade and the fixed blade are arranged in a plurality of stages. On a disk-shaped base, a rotating body that is levitated and held by a magnetic bearing, a motor that rotationally drives the rotating body, a plurality of rotating blades attached to the rotating body, and these rotating blades are alternately arranged. A fixed wing, a fixed wing spacer that holds the fixed wing in a fixed position, and a cylindrical base that is connected to the disk-shaped base and covers the rotating body, the motor, the rotating wing, the fixed wing, and the fixed wing spacer. A casing, and
In the vacuum pump that exhausts from the intake port to the exhaust port by the interaction between the rotary blade and the fixed blade by rotating the rotating body by the motor,
A part of the gas on the exhaust port side is provided with a backflow path in which the gas flows back to the intake port side;
A vacuum pump characterized in that an inlet and an outlet of the reverse flow path are provided in a blade exhaust portion where the rotary blade and the fixed blade are arranged in a plurality of stages.   6. The vacuum pump according to claim 3, wherein at least one stage of fixed blades or rotor blades is disposed on the exhaust port side from a position where the inlet of the reverse flow path is provided.   The vacuum pump according to claim 4 or 5, wherein at least one stage of fixed blades or rotor blades is disposed on the intake port side from a position where the outlet of the reverse flow path is provided. The outlet of the backflow path is provided at a plurality of locations where the backflow path is branched,
The at least one pair of the said exit is arrange | positioned in the position which opposes on both sides of the rotating shaft of a rotary body, or the said exit is arrange | positioned in the position of the vertex of a regular polygon. Item 8. The vacuum pump according to any one of Items 7.   The vacuum according to claim 2 or 8, wherein an adjustment valve for adjusting a flow rate of gas passing through the backflow path is provided between an inlet of the backflow path and a position where the backflow path is branched. pump.   A seal member is provided for isolating the gas path and the gap so that gas does not leak into the gap between the casing provided with the outlet of the reverse flow path and the fixed blade spacer or the fixed blade rim. The vacuum pump according to any one of claims 3 to 9, wherein the vacuum pump is characterized.   The vacuum pump according to claim 10, wherein the seal member is provided in two upper and lower stages inside the entire circumference of the casing.   The vacuum pump according to claim 10 or 11, wherein the seal member is an O-ring.   The vacuum pump according to claim 10 or 11, wherein the seal member is a protrusion provided on a rim of the fixed blade spacer or the fixed blade.   The vacuum pump according to claim 13, wherein the protrusion height of the protrusion portion becomes smaller as the position is closer to the intake port.   The vacuum pump according to claim 10 or 11, wherein the seal member is a protrusion provided on an inner peripheral surface of the casing.   The vacuum pump according to claim 15, wherein the protrusion height of the protrusion portion becomes smaller as the position is closer to the exhaust port.   The vacuum pump according to any one of claims 1 to 16, further comprising a rotation speed control means for controlling a rotation speed of the rotor blade.

Images