JPH0540319Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) The present invention relates to improvements in vortex compression pumps.

(Prior Art) Conventionally, vacuum pumps suitable for removing air from sealed chambers in semiconductor manufacturing equipment, electron microscopes, etc. and creating a clean vacuum have been used, for example, by
As disclosed in Publication No. 60-252197, in a casing provided with a suction port open to the vacuum chamber side and a discharge port open to the atmosphere side, there is a casing that extends from the suction port side to the discharge port side. Formerly a screw groove compression pump,
Sequential arrangements of centrifugal compression pumps and vortex compression pumps are known.

(Problems to be Solved by the Invention) Incidentally, the vortex type compression pump used in the vacuum pump as described above generally operates by rotating an axial flow impeller having a large number of blades facing inside the housing by the rotational movement of a rotating shaft. By rotating the housing, the gas is compressed while being moved from the suction port side to the discharge port side while making a spiral movement within the housing. Since the gas spiraling inside the housing generates heat during the compression process, the change in compression results in so-called polytropic compression. Such polytropic compression is undesirable because the amount of work required for compression increases compared to so-called isothermal compression in which the gas is compressed while keeping its temperature constant.

The present invention was developed in view of the above, and its purpose is to create a housing structure in which the gas sucked from the suction port is circulated by the rotational movement of the axial flow impeller in order to compress the gas. By improving this, it is possible to efficiently dissipate heat from the gas generated during the compression process, thereby reducing the amount of work required for compression by making the compression change into isothermal compression instead of polytropic compression. . Further, there is no need to separately provide a special device for this purpose, thereby avoiding an increase in the size of the vortex compression pump.

(Means for Solving the Problems) In order to achieve the above object, the present invention is arranged in a casing 1 provided with a suction port 2 and a discharge port 3, and is rotated by the drive of a drive motor 4. A rotary shaft 5 and an axial flow that is rotatably supported by the rotary shaft 5 and compresses gas sucked into the casing 1 from the suction port 2 in the housing 11 and discharges it out of the casing 1 from the discharge port 3. The object is a vortex compression pump equipped with an impeller 10,
The following solutions were taken.

That is, the solution means of the present invention is to divide the housing 11 into two parts on both sides of the axial impeller 10 into a first housing part 15a and a second housing part 15b. An annular main flow passage 12 for gas circulation is formed between the housing part 15b and the housing part 15b. Furthermore, the first and second housing portions 15a forming the main flow path 12,
Both annular wall portions 15c, 15c of 15b are formed thinner than other portions. Further, the first and second housing portions 15 are arranged such that the annular hollow portions 13, 13 through which the cooling fluid circulates surround the main flow path 12 via the annular thin wall portions 15c, 15c.
A and 15b are formed respectively.

(Function) With the above configuration, in the present invention, when the axial flow impeller 10 rotates due to the rotational movement of the rotating shaft 5 due to the start of the drive motor 4, gas is sucked into the casing 1 through the suction port 2, This casing 1
The gas sucked into the housing 11 is introduced into the housing 11 and compressed.

The gas introduced into the housing 11 and generated heat by compression is transferred to the first housing part 15a and the second housing part 15a.
While being circulated and discharged through the annular main flow path 12 formed between the housing part 15b, the main flow is discharged through the annular thin wall parts 15c, 15c of the first and second housing parts 15a, 15b. Heat is efficiently radiated to the cooling fluid in the hollow parts 13, 13 formed so as to surround the passage 12, through the thin wall parts 15c, 15c.

In other words, since the hollow portions 13, 13 surround the entire circumference of the main flow path 12 with the thin wall portions 15c, 15c in between, the heat transfer area is expanded as much as possible, and the entire main flow path 12 is cooled at once. Furthermore, the heat transfer resistance is reduced due to the thin wall thickness of the heat transfer area, and the gas generated by compression is quickly cooled down.

Therefore, the compression change of the gas does not become polytropic compression, but isothermal compression is performed, and the amount of work required for compression is reduced.

Further, since the housing 11 is configured as described above, there is no need to separately provide a device for cooling compressed gas, and thus an increase in the size of the vortex type compression pump can be avoided.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows a vortex compression pump according to an embodiment of the present invention, in which a suction port 2, which is opened to the vacuum chamber side of a semiconductor manufacturing device (not shown), is located on the upper surface, and a discharge port 1 is opened to the atmosphere. Reference numeral 3 denotes a cylindrical casing provided on each lower side surface; 4 a drive motor consisting of a rotor 4a and a stator 4b disposed on the bottom side of the casing 1; and 5 a vertical direction at the center of the casing 1. The rotating shaft 5 is provided with a cylindrical boss member 6 externally fitted to rotate integrally with the rotating shaft.

The boss member 6 is rotatably supported by the rotary shaft 5 in the middle in the vertical direction, and the gas in the vacuum chamber sucked into the casing 1 from the suction port 2 is compressed in a housing 11 to be described later. A pair of upper and lower axial flow impellers 10, 10 for discharging out of the casing 1 from the discharge port 3 are horizontally supported at a predetermined interval, while the above-mentioned axial flow impellers 10, A pair of upper and lower annular housings 11, 11 are supported and formed horizontally in correspondence with the housings 10.

In addition, as a feature of the present invention, each housing 1
1 is configured to be divided vertically into two into an upper annular first housing part 15a and a lower annular second housing part 15b on both upper and lower sides of each axial flow impeller 10, and the first housing part 15a is divided into two parts. An annular main channel 12 for gas circulation, which has a vertically elongated elliptical cross section, is formed between the second housing portion 15b and the second housing portion 15b. That is, the lower surface of the first housing part 15a is formed as a concave curved surface curved upward, while the upper surface of the second housing part 15b is formed as a concave curved surface curved downward, and this double concave curve The annular main flow path 1 is formed by both the annular walls 15c and 15c.
2 is formed. Further, as a feature of the present invention, both the annular wall portions 1 of the first and second housing portions 15a and 15b forming the main flow path 12 are
5c and 15c are formed thinner than other parts,
Heat transfer resistance is reduced. Each of the axial flow impellers 10 has a large number of blades 10a, 10a, . By being rotated, the gas sucked into each main flow path 12 is transferred and compressed.

Furthermore, the first and second housing parts 15
a, 15b, two upper and lower cooling fluid circulation hollow portions 13, 13 in which cooling fluid such as water circulates surround the main flow path 12 via the annular thin wall portions 15c, 15c, respectively. It is formed. Further, the first and second housing parts 1
5a and 15b, a cooling fluid supply cylinder member 16a passes through one side (left side in the figure) of the side wall of the casing 1 and communicates with each hollow part 13, and a cooling fluid supply cylinder member 16a passes through the other side (right side in the figure). Cooling fluid circulation cylinder members 16b communicating with each of the hollow portions 13 are formed. And each of the above-mentioned supply cylinder members 16
The cooling fluid supplied into each of the hollow portions 13 from a is circulated through each of the hollow portions 13, and then discharged to the outside from each of the reflux cylinder members 16b and circulated again to each of the supply cylinder members 16a. is being done.

Further, the first housing portion 15a of each of the housings 11 has a suction passage 11b for sucking gas into the main flow path 12, and the second housing portion 15
A discharge passage 11c for discharging the gas circulated within the main passage 12 is provided in each of the parts b.
And the discharge passage 1 of the upper housing 11
1c and the suction passage 11b of the lower housing 11 are cooled, and the gas in the vacuum chamber sucked through the suction port 2 is first drawn into the main passage 12 of the upper housing 11 and circulated. After that, it is sucked into the main channel 12 of the lower housing 11 and circulated, and then discharged out of the casing 1 through the discharge port 3.

Furthermore, as shown in FIGS. 2 and 3, each housing 11 is provided with a stripper portion 11a so as to separate the main flow path 12 between the suction passage 11b and the discharge passage 11c. The gas sucked in from the passage 11b and the gas discharged from the discharge passage 11c are prevented from merging.

Further, in the main flow path 12 of each of the housings 11, there is an annular guide member 14 that guides the gas flow in close proximity to the outer circumference of the axial flow impeller 10 that rotates when the drive motor 4 is started. It is arranged to correspond to the rotation axis of the axial flow impeller 10.

In this way, while the gas sucked into the main flow path 12 from the suction passage 11b of each of the housings 11 is discharged from the discharge passage 11c, the guide member 14 is caused to spiral around the guide member 14 an appropriate number of times, and the shaft is moved an appropriate number of times. A vortex-type compression pump is constructed with two pump stages, which transverse the flow impeller 10 and in each case receive kinetic energy from the axial flow impeller 10.

Next, the operation of the vortex compression pump according to the above embodiment will be explained.

First, when the drive motor 4 starts, gas in the vacuum chamber is sucked into the casing 1 through the suction port 2 . This sucked gas is introduced into the upper main passage 12 from the suction passage 11b of the upper housing 11, circulates within the upper main passage 12 while spirally moving around the guide member 14, and is compressed. During this time,
The gas generates heat due to compression, but the heat is removed by the cooling fluid circulating in the hollow parts 13, 13 of the first and second housing parts 15a, 15b.

In other words, since the hollow portions 13, 13 surround the entire circumference of the main flow path 12 with the thin wall portions 15c, 15c in between, the heat transfer area can be expanded as much as possible, and the entire main flow path 12 can be cooled at once. Moreover, since the wall thickness of the heat transfer area is thin, the heat transfer resistance is reduced, and the gas generated by compression can be quickly cooled. Therefore, the compression change of the gas does not result in polytropic compression, but isothermal compression is performed, and the amount of work required for compression can be reduced.

Next, the gas that has circulated in the upper main channel 12 of the upper housing 11 is transferred to the upper housing 1.
1 discharge passage 11c and lower housing 11
the lower housing 11 through the suction passage 11b of
is introduced into the lower main flow passage 12 of
2 and is further compressed. Even in this case, heat is removed from the gas that generates heat due to compression by the cooling fluid circulating through the first and second housing parts 15a and 15b. Therefore, the compression change of the gas does not become polytropic compression, and the gas is subjected to isothermal compression. This makes it possible to reduce the amount of work required for compression.

Furthermore, since the two upper and lower compressed gas cooling hollow parts 13, 13 are formed around each main flow path 12 as described above, the space that was conventionally a dead space around the housing 11 in the casing 1 can be effectively utilized. Thereby, there is no need to separately provide a device for cooling the compressed gas, and it is therefore possible to avoid increasing the size of the vortex compression pump.

Furthermore, in the above embodiment, since the guide member 14 is disposed in each main channel 12 of the upper and lower housings 11, 11, the gas introduced into each of the main channels 12 is 14, smoothly spirals around it a suitable number of times, efficiently crosses the axial flow impeller 10 the number of times, receives kinetic energy from the axial flow impeller 10 each time, and thereby each of the above housings It is also possible to achieve the effect that the gas flows smoothly within the compressor 11 and the compression ratio thereof can be further increased.

In the above embodiment, the vortex compression pump is configured with two pump stages, but the present invention is not limited to this, and it goes without saying that the pump may have one stage or three or more stages, for example.

(Effects of the invention) As explained above, according to the invention, the housing 11 in which the gas in the vacuum chamber etc. sucked into the casing 1 from the suction port 2 is compressed is arranged on both sides of the axial flow impeller 10. The first housing part 15a and the second housing part 15b are divided into two parts, and an annular main passage 12 for gas circulation is formed between the first housing part 15a and the second housing part 15b, and a cooling fluid Annular hollow portions 13, 13 through which water circulates are formed in the first and second housing portions 15a, 15b, respectively, so as to surround the main flow path 12 via annular thin wall portions 15c, 15c. Therefore, the heat of the gas generated by being compressed within the housing 11 is transferred to the housing 11.
While being circulated inside and discharged, the hollow part 13,1
Heat can be efficiently dissipated to the cooling fluid in the cooling fluid in a short period of time, and as a result, the compression change of the gas is made isothermal compression without polytropic compression, and the amount of work required for compression can be reduced.

Furthermore, since the two upper and lower compressed gas cooling hollow portions 13, 13 are formed around each main flow channel 12 as described above, there is no need to separately install a compressed gas cooling device, and this makes it possible to use a vortex-type compression pump. Enlargement can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing a vortex compression pump according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG.
It is a longitudinal side view seen from a different angle from the figure. DESCRIPTION OF SYMBOLS 1... Casing, 2... Suction port, 3... Discharge port, 4... Drive motor, 5... Rotating shaft, 10...
... Impeller, 11 ... Housing, 12 ... Main channel, 13 ... Hollow part, 15a ... First housing part, 15b ... Second housing part, 15c ... Wall part.

Claims (1)

[Claims for Utility Model Registration] A rotary shaft 5 which is arranged in a casing 1 provided with a suction port 2 and a discharge port 3 and is rotated by the drive of a drive motor 4; The vortex-flow type compression pump is equipped with an axial flow impeller 10 that is supported and compresses gas sucked into the casing 1 from the suction port 2 within the housing 11 and discharges the gas from the discharge port 3 to the outside of the casing 1. The housing 11 is divided into a first housing part 15a and a second housing part 15b on both sides of the axial impeller 10, and there is a gap between the first housing part 15a and the second housing part 15b. An annular main channel 12 for gas circulation is formed in the annular wall portions 1 of the first and second housing portions 15a and 15b forming the main channel 12.
5c and 15c are formed thinner than other parts, and furthermore, the first and second housing parts 15
In a, 15b, an annular hollow part 13, 13 through which a cooling fluid circulates is provided in both annular thin wall parts 15c, 1.
A vortex compression pump characterized in that each of the pumps is formed so as to surround the main flow path 12 via the main flow path 5c.