JPH03182697A - Vacuum pump - Google Patents

Abstract

PURPOSE:To improve the efficiency of an intermediate stage without reducing a discharge speed in a range of 10-0.1Torr and to reduce size through reduction of the number of stages by forming a vortex friction pump, in which the delivery port of a vortex chamber on the low pressure chamber side and a suction port on the high pressure side are commonly used, with rotary discs and static discs. CONSTITUTION:A rotary disc 1B at an intermediate stage is provided with a plurality of recesses X and Y formed in the shape of a semicircle or a bow in a cross section along the peripheral direction, and blades Z in the radial direction are formed between the adjoining recesses X and between the adjoining recesses Y. A static disc 4B at an intermediate stage is provided with vortex chambers R on the low pressure side and vortex chambers S on the high pressure side formed in an arcuate shape in a cross section along the peripheral direction. The vortex chamber R on the low pressure side is provided with a suction port U and a delivery port V, and the vortex chamber S on the high pressure side with a delivery port V'. The delivery port V of the vortex chamber R on the low pressure side is additionally functioned as the suction port of the vortex chamber S on the high pressure side, and a radially extending two-stage vortex friction pump is formed on an opposing surface between the static disc 4B and the rotary disc 1B. A radially extending three-stage vortex friction pump is formed on an opposing surface between the rotary disc 1B and a static disc 4C.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a vacuum pump installed in the vacuum exhaust section of semiconductor manufacturing equipment or food manufacturing equipment (a vacuum pump that creates a clean vacuum without using sealants such as oil). ).

(Prior Art) In an oil rotary pump or the like, when oil vapor as a sealant inside the pump diffuses back into the equipment 1 to be evacuated, such as semiconductor manufacturing equipment or food manufacturing equipment.

Since this adversely affects the products made with these semiconductor manufacturing equipment and food manufacturing equipment, vacuum pumps are installed in the vacuum exhaust parts of these equipment to create a clean vacuum without using sealants such as oil.

This vacuum pump consists of a rotating disk and a stationary disk that face each other with a narrow gap so that the pressure of semiconductor manufacturing equipment or food manufacturing equipment to be evacuated can be evacuated from atmospheric pressure to 10 to 10-7. are combined in multiple stages. Moreover, it is necessary to handle a wide range of vacuum regions, and in order to obtain good exhaust performance in everything from the turbulent region to the molecular region, in the stage near atmospheric pressure, the A spiral groove is provided to configure a friction pump with a spiral groove on one side, and on the high vacuum side, a spiral groove is provided only on one of the facing surfaces of the one-rotation disk and the stationary disk to form a friction pump with a spiral groove on one side. It constitutes a friction pump. By rotating the rotary disk at high speed, it is possible to evacuate from atmospheric pressure to high vacuum with a single vacuum pump. When this vacuum pump is used, oil vapor can be evacuated from devices such as semiconductors. It has the advantage of not back diffusing into manufacturing equipment or food manufacturing equipment.

A conventional example of this vacuum pump is explained with reference to Fig. 4.5. (01) is the rotor, (Ola) is the same rotor (10).
), (02) is a casing, (02a) is a stationary disk provided in multiple stages on the inner circumferential surface of the casing (02), (02a,) is each stationary circle of the same A spiral groove provided on the surface of the plate (02a) facing the rotating disk allows each of the stationary disks (02a) and each of the rotating disks (Ola
) are facing each other with a narrow gap. Also, (03) is the main shaft that supported the rotor (Ol), and (010) is the motor casing.

(04) is the motor rotor attached to the main shaft (03).

(05) is the motor stator attached to the motor casing (010), and (06) is the upper bearing of the main shaft (03).

(07) is the lower bearing of the main shaft (03), (08) is the suction port provided in the upper part of the casing (02), (0
9) is an exhaust port provided at the bottom of the casing (02);
(011,) is the cooling jacket provided around the motor casing (010), (012) is the cooling water outlet of the cooling jacket (011), and (015) is the bottom of the motor casing (010). Installed oil tank/lower casing.

(016) is the plywood attached to the lower part of the lower casing (015), (014) is the lubricating oil in the oil tank and lower casing (015), which is connected to the motor rotor (04) and motor stator (05). , the main shaft (03), the rotor (01), and each rotating disk (Ola) are rotated to remove the suction port (0) from the semiconductor manufacturing equipment or food manufacturing equipment at atmospheric pressure.
8) The gas inhaled is accelerated by the viscosity of the gas.

Moreover, the air is exhausted through the exhaust port (09) while being rotated by a spiral groove (02a1) provided on the surface of each stationary disk (02a) facing the rotating disk. This vacuum pump (Sieghahn vacuum pump) does not use liquids such as oil like oil rotary pumps.

Equipment that should evacuate oil vapor as mentioned above.

For example, it will not be diffused back into semiconductor manufacturing equipment or food manufacturing equipment.

(Problem to be solved by the invention) In the conventional vacuum pump shown in FIGS. 4 and 5 above.

It combines a friction pump with spiral grooves on both sides and a friction pump with spiral grooves on one side. Among these friction pumps, in a turbulent region near atmospheric pressure, the stage with a friction pump with spiral grooves on one side performs a large exhaust work, and in the single-layer region and molecular region, the stage with a friction pump with a spiral groove on one side performs a large work. However, in the slip region, the pumping speed of the friction pump with the one-sided spiral groove decreases. For this reason, a large number of stages is required, making the vacuum pump larger. In addition, during excessive pumping from atmospheric pressure to high vacuum, 10 to 0
, I TorrO becomes small, and there is a problem in that a large amount of time is required for evacuation during this period. For reference, the relationship between pumping speed and degree of vacuum is shown in Figure 6.

The present invention is proposed in view of the above-mentioned problems, and its objectives are as follows: 10=0. The pumping speed does not decrease even in the ITorr range. Another object of the present invention is to provide a vacuum pump that can improve the efficiency of the intermediate stage when operating under rated vacuum conditions, reduce the number of stages, and reduce the size of the vacuum pump.

(Means for Solving the Problems) In order to achieve the above object, the present invention combines a plurality of rotating disks and stationary disks facing each other with a narrow gap, and A spiral groove is provided on at least one side of each stationary disk.

In a vacuum pump that constitutes a spiral groove friction pump and exhausts gas from an intake port to an exhaust port by the viscous friction of the gas when each of the rotating disks is rotated at high speed, an intermediate stage of each of the rotating disks is used. A plurality of recesses with semicircular or arcuate cross sections are provided along the circumferential direction in the rotating disk of Multiple arc-shaped spiral chambers are provided along the circumference.

Each of the volute chambers is provided with a suction chamber and a discharge chamber, and the rotating disk and stationary disk at the intermediate stage form a vortex friction pump in which the discharge port of the low-pressure side volute chamber and the high-pressure side suction port are common. are doing.

(Function) The vacuum pump of the present invention is constructed as described above.
For a friction pump with a single-sided spiral groove that serves a laminar region, a slip region, and a nine-layer region, it is necessary to select a spiral groove depth that is several times the gap between the one-rotation disk and the stationary disk, depending on its optimum pumping performance. .

As the groove depth becomes relatively shallow, there is a tendency for the Raynozzle number R@ and Kutdsen number that govern the flow to become smaller.
The intermediate stage volute friction pump can increase the groove depth of the volute chamber from several times to more than ten times the spiral groove depth. Furthermore, the radial primary and secondary flows created by the rotating disk disturb the flow within the vortex chamber.

Even if the gap in the swirl chamber is large, the speed in the swirling direction can be increased. As a result, the pumping speed does not decrease even in the range of 10 to 0 Torr, where pumping performance is difficult to obtain with a friction pump with a spiral groove on one side.

(Example) Next, the vacuum pump of the present invention will be explained using an example shown in Fig. 1.2.3.
C) is a rotating disk, (4B) (4C) is the same rotating disk C
IA) (IB) (1C) are stationary disks facing each other with a narrow gap, and a friction pump with one single-sided spiral is constructed on the opposing surfaces of the 9-rotating disk (IA) and the stationary disk (4B). , the opposing surface between the stationary disk (4B) and the rotating disk (IB>,
Nine spiral friction pumps of the present invention are constructed on the opposing surfaces of the rotating disk (1B) and the stationary disk (4C).
A friction pump having one spiral on one side is constructed on the opposing surface of C) and the rotating disk (IC). In addition, as shown in FIG. 2, the intermediate rotating disk (IB) is provided with a plurality of recesses (X) and (Y) having semicircular or arcuate cross sections along the circumferential direction, and adjacent recesses Form a radial vane (Z) between (X) and (Y). In addition, as shown in Figure 1.3, the intermediate stage stationary disk (4B) is provided with a low-pressure side spiral chamber (R) and a high-pressure side spiral chamber (S) having an arc-shaped cross section along the circumferential direction. , the low pressure side spiral chamber (R) is provided with an inlet (U) and a discharge port (V), the high pressure side spiral chamber (S) is provided with a discharge port (V''), and the low pressure side spiral chamber (R) is provided with a discharge port (V''). ) outlet (
V) is also used as the suction port of the high-pressure side volute chamber (S), and a two-stage volute friction pump is installed in the radial direction on the opposing surface of the stationary disk (4B) and the rotating disk (IB). Three stages of volute friction pumps are arranged in the radial direction on the opposing surfaces of the one-rotation disk (IB) and the stationary disk (4C). Note that each of the swirl chambers (R) (S) becomes shallower from the suction port toward the discharge port. Further, the discharge port (V') opens to the next stage friction pump.

In addition, in the above-mentioned spiral friction pump, the pressure increases from the spiral chamber (R) to the spiral chamber (S), and the density of the gas increases. The flow rate in the swirling direction of the gas is kept approximately constant based on the flow path area. Two spiral chambers (R) and two spiral chambers (S) having the same size and shape are arranged at symmetrical positions with respect to the axis. In addition, the pressure ratio of the -stage centrifugal friction pump is small, so it is necessary to combine multiple stages in series. In this example.

There are a total of 5 stages on the top and bottom surfaces of one rotating disk (IB), but by making it at least 2 stages on one side of 9.

The suction port and discharge port can be rationally and compactly arranged.

Next, the operation of the vacuum pump shown in FIG. 1.2.3 will be explained in detail. Laminar basin, slip basin.

A friction pump with a spiral groove on one side that shares the molecular flow area (friction pump configured on the opposing surfaces of a rotating disk (IA) and a stationary disk (4B), a 9-rotation disk (1B), and a stationary disk (4C))
Due to its optimum pumping performance, the friction pump configured on the opposing surface of It is necessary to select a spiral groove depth that is several times the gap or less.
The groove depth becomes relatively shallow, and the Raynozzle number R3 and Kutdsen number, which govern the flow, tend to be smaller than 7.

h R, - where V: circumferential speed, h: gap + spiral groove depth, D:
The kinematic viscosity coefficient of gas is = h/λ, where λ: Mean free path of gas molecules In a volute friction pump, the groove depth of the volute chamber (R) (S) is several times to ten times the spiral groove depth. Can be done. Moreover, the radial primary and secondary flows created by the rotating disk (1B) disturb the flow in the swirl chamber (R) (S),
Even if the gap between R) and (S) is large, the speed in the turning direction can be increased. As a result, it is difficult to obtain exhaust performance with a friction pump with a spiral groove on one side.
The pumping speed does not decrease even in the Torr range.

(Effects of the Invention) As described above, in the vacuum pump of the present invention, among the rotating disks,
A plurality of recesses each having a semicircular or arcuate cross section are provided along the circumferential direction on the rotating disk of the intermediate stage, and lIj! ! A radial blade is formed between the adjacent recesses, and a plurality of spiral chambers each having an arc-shaped cross section are provided along the circumferential direction on the stationary disk at the intermediate stage, and each spiral chamber has a suction chamber and a discharge chamber. The rotating disk and stationary disk at the intermediate stage form a volute friction pump in which the discharge port of the low-pressure side volute chamber and the high-pressure side suction port are common. In the pump, the groove depth of the vortex chamber can be made several times to more than ten times the spiral groove depth. Moreover, due to the radial flow created by the rotating disk,
Even if the flow in the vortex chamber is disturbed and the gap in the vortex chamber is large,
The speed in the turning direction can be increased. This result 1
Difficult to obtain exhaust performance with a friction pump with a spiral groove on one side 1
0~0. The pumping speed does not decrease even in the ITorr range. In addition, as mentioned above, a vortex friction pump is configured in the intermediate stage, which improves the efficiency of the intermediate stage when operating under rated vacuum conditions, reduces the number of stages, and has the effect of downsizing the vacuum pump. .

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing one embodiment of a vacuum pump according to the present invention, FIG. 2 is a cross-sectional plan view taken along the line ■-■ in FIG. 1, and FIG. FIG. 4.5 is a vertical cross-sectional side view showing a conventional vacuum pump, and FIG. 6 is an explanatory diagram showing the relationship between pumping speed and degree of vacuum of the same vacuum pump. (LA) (1B) (IC)...Rotating disk, (4
B) (4C) ...stationary disk, (X) (Y)
...A semicircular or arcuate depression. (Z) - Vane, (R) (S) - Swirl chamber, (U) - Suction port of swirl chamber (R), (V) - Discharge port of swirl chamber (R) and spiral chamber (S) Suction port, (V') ・Discharge port of swirl chamber (S).

Claims (1)

[Claims] Rotating disks and stationary disks facing each other with a narrow gap are combined in multiple stages, and a spiral groove is provided in at least one of the rotating disks and the stationary disk, thereby creating a spiral groove friction pump. In the vacuum pump, which exhausts gas from the intake port to the exhaust port by the viscous friction of the gas when the respective rotating disks are rotated at high speed,
A plurality of recesses with semicircular or arcuate cross sections are provided along the circumferential direction in the rotating disk of the intermediate stage, and radial blades are formed between adjacent recesses. A plurality of arc-shaped spiral chambers are provided along the circumferential direction, and each spiral chamber is provided with a suction chamber and a discharge chamber, and the low-pressure side spiral chamber is A vacuum pump characterized by forming a spiral friction pump having a common discharge port and high-pressure side suction port.