WO1995028571A1

WO1995028571A1 - Molecular pump

Info

Publication number: WO1995028571A1
Application number: PCT/CN1994/000075
Authority: WO
Inventors: Jiguo Chu
Original assignee: Jiguo Chu
Priority date: 1994-04-16
Filing date: 1994-09-24
Publication date: 1995-10-26
Also published as: AU7738294A; CN1110376A

Abstract

The present invention relates to a molecular pump having air suction grooves which have a rectangle-shaped section and typical protruded or inclined side-walls toward the rotary direction of the pump. Some single/basic air suction units concentrically mounted provide a multistage air suction unit composed in series or parallel connection. The single- and multi-stage units concentrically mounted with other molecular pump or rotary mechanical pump can form a compound vacuum pump with good operation performance, fast suction speed and high compression ratio.

Description

Drag molecular pump

The invention relates to a drag molecular pump.

Say

Background technique

The cross section of the pumping trough of existing drag molecular pumps adopts a rectangular structure, for example, the famous disc-shaped single drag pump (

Siegbahn molecular pump), cylindrical single drag pump (Ho i we ek molecular pump), and Chinese patent CN- 8 5 1 05304. 1, CN-Π 1 0 1 1 1 6. 6 -2, CN-92 1 0 1 300. 0 and U.S. patents

Drag the molecular pump on. This type of molecular pump cannot make full use of the drag speed obtained by gas molecules, and its pumping speed and compression ratio are both low. Disclosure of invention

An object of the present invention is to provide a drag molecular pump (referred to as an oblique drag pump for short) with a non-rectangular cross-section suction tank, wherein the suction tank is provided with a drag surface and referred to as a single oblique drag pump, and the suction tank is provided with The two drag surfaces are referred to as double oblique drag pumps).

The inclined trailing pump provided by the present invention is composed of a moving wheel, a stationary wheel, a rotating shaft, a pump casing and the like. It is characterized in that the pump has at least one set of basic suction units. The suction groove of the basic suction unit adopts a non-rectangular cross section. Its typical structure is that the cross section of the suction groove is inclined or convex toward the dragging direction, thereby improving the strength of the impeller. In addition, the drag speed obtained by the gas molecules can be fully utilized to improve the pumping speed and compression ratio of the pump.

Several groups of the above-mentioned basic suction units are installed coaxially, and their intake ports and exhaust ports are respectively connected to form parallel extraction. Connecting their air inlets and exhaust outlets one after the other in order can form a series exhaust. The suction unit near the pump inlet is pumped in parallel, and the suction unit near the pump exhaust port is pumped in series.

The above-mentioned single-stage or multi-stage oblique drag pump suction unit and various molecular pumps, for example, a turbo molecular pump, a disc-shaped single drag pump, a cylindrical single drag pump, or a rotary mechanical pump, or a combination of these are installed coaxially, and The combination of series and parallel can form a composite vacuum pump with better performance.

Advantages of the invention:

1. The drag molecular pump provided by the present invention can make full use of the drag speed obtained by gas molecules, and improve the pumping speed and compression ratio of the pump.

Replacement page (Article 26) 2. The drag molecular pump impeller proposed by the present invention has high strength and good processability. Brief description of the drawings

The present invention is further described below with reference to the drawings and examples.

Figure 1 is a schematic diagram of a single-stage disc-shaped single oblique drag pump.

Fig. 2 is a schematic diagram of a single-stage disc-shaped single oblique drag pump static wheel.

Figure 3 is a schematic diagram of a single-stage cylindrical single oblique drag pump.

Figure 4 is a schematic diagram of a single-stage disc-type double oblique drag pump.

Fig. 5 is a schematic diagram of a single-stage disc-shaped double oblique drag pump moving wheel.

Fig. 6 is a schematic diagram of a single-stage disc-shaped double oblique drag pump static wheel.

Figure 7 is a schematic diagram of a single-stage cylindrical double oblique drag pump.

Figure 8 shows a horizontal compound disc-shaped double oblique tow pump (1).

(Picture!) Is a horizontal composite disc-shaped double oblique tow pump (2).

Figure 10 is a vertical composite disc-shaped double oblique drag pump.

Figure 11 shows a vertical compound cylindrical double oblique drag pump.

Figure 12 is a schematic diagram of a disc-shaped oblique drag pump with optimized structure.

Figure 13 is a schematic diagram of the spacer ring (1) of the disc-shaped inclined tow pump with optimized structure.

Figure H is a schematic diagram of a spacer ring (2) of a disc-shaped inclined tow pump with an optimized structure.

Figure 15 is a schematic diagram of a disc-shaped double oblique drag pump with optimized structure.

The best way to implement the invention

Example of real drag: Single-stage disc-shaped single oblique drag pump

A single-stage disc-shaped single-slope drag pump is shown in Figure 1, and consists of a rotating shaft 1, a moving wheel 2, a static wheel 3, a spacer ring 4, and a pump casing 5.

The moving wheel 2 is composed of a flat disk. As shown in FIG. 2, the static wheel 3 is constituted by a disc provided with a plurality of spiral suction grooves 6. The wall 7 of the suction tank is inclined in the dragging direction (the direction indicated by the solid line arrow in FIG. 2), so that the combined speed of the drag speed obtained by the gas molecules and the thermal motion speed (shown by the dotted arrow in FIG. 2) and the slot The wall direction is consistent, so that the drag speed obtained by the gas is fully utilized, and the pumping speed and compression ratio of the pump are improved.

When the moving wheel rotates at high speed, the pumped gas is pumped from the outside to the inside. Changing the spiral direction of the suction slot, or the direction of the drag (that is, the rotation direction of the moving wheel), can change the suction direction. If the dragging direction is changed, the tilting direction of the groove wall 7 is changed accordingly.

If the pumped gas enters or exits the pumping unit axially from the outside of the moving wheel, a row of short turbo-molecular pump blades can be added to the outside of the moving wheel disc on one side of the moving wheel.

Replacement page (Article 26) This coincides with the flow direction of the pumped gas.

The moving wheel disc can also be machined to be thinner and thicker on the outside, while the stationary impeller is thicker and thinner on the outside. The axial clearances of the moving and stationary wheels are approximately equal.

The dynamic and static wheel structures of the disc-shaped single-slant drag pump can be interchanged.

Example two: Single-stage cylindrical single-slope drag pump.

The single-stage cylindrical single-sloping tow pump is shown in Fig. 3 and consists of a rotating shaft 1, a moving wheel 8, a static wheel 9 and a pump casing 5. The moving wheel 8 is composed of a cylindrical surface. The static wheel 9 is composed of a cylindrical surface provided with a plurality of helical suction grooves 1 G, and the suction groove groove wall 11 is inclined in the dragging direction, so that the combined speed of the drag speed obtained by the gas molecules and the degree of thermal motion and The direction of the groove wall matches to make full use of the drag speed. Changing the spiral direction of the suction slot, or the direction of the drag (that is, the rotation direction of the moving wheel), can change the suction direction. If the dragging direction is changed, the inclination direction of the groove wall 11 is changed accordingly.

The dynamic and static wheel structures of the cylindrical single oblique drag pump are interchangeable.

Example three: Single-stage disc-shaped double oblique drag pump

The single-stage disc-type double oblique tow pump is shown in Fig. 4 and consists of a rotating shaft 1, a moving wheel 1 2, a static wheel 1 3, a dynamic seal 1 4, a spacer ring 4 and a pump casing 5.

The moving wheel 12 is composed of two coaxial flat disks. As shown in FIG. 5, one flat disk (the left flat disk in FIG. 4) is provided with a plurality of air holes 15 near the rotating shaft. As shown in FIG. 6, the static wheel 13 is composed of a plurality of spiral blades 16 and its fixing device Π, and the middle section of the blade 16 is convex toward the dragging direction (the direction shown by the solid arrow in FIG. 6) to form The chamfered shape (as shown in FIG. 6), or an arc shape, or other shapes, makes the combined speed of the drag speed obtained by the gas molecules and the thermal motion speed (shown by the dashed arrow in FIG. 6) consistent with the direction of the groove wall, so that , Make full use of the drag speed obtained by the gas molecules. The blade fixing device should minimize the resistance of the gas in the suction direction. The dynamic seal 14 may be a disc-shaped single-pull pump static wheel, or a disc-shaped single-slant pump static wheel, or other dynamic sealing device.

The static wheel 1 3 is installed in the middle of the two movable wheels 1 2, and the dynamic seal 14 is installed outside the movable wheel provided with air holes. There is a working gap between the moving and static parts. If the radial gap doubles as a gas passage, the radial gap is large.

If the radial clearance between the moving wheel 12 and the spacer ring 4 is small, the dynamic seal 1 4 may not be used.

When the moving wheel rotates at a high speed, the space 1 between two adjacent stationary wheel blades becomes a suction groove with two drag surfaces, and the pumped gas is pumped from the outside to the inside rotation axis in the radial direction. Changing the spiral direction of the static wheel blade 16 or the dragging direction (that is, the rotating direction of the moving wheel) can change the suction direction. If the dragging direction is changed, the convex direction of the static wheel blade is changed accordingly.

The moving wheel disk can also be processed into thin outer thickness and thin inner thickness, and the static wheel and dynamic seal have thin outer thickness and inner thin thickness. The axial clearance between the moving and static parts is approximately equal.

Example 4: Single-stage cylindrical double inclined pump

The single-stage cylindrical double oblique drag pump is shown in Fig. 7 and consists of a rotating shaft 1, a moving wheel 19, a static wheel 20, a dynamic seal 21, and a pump casing 5.

The moving wheel 19 is composed of two coaxial cylindrical surfaces. The static wheel 20 is composed of a plurality of spiral blades 22 and a fixing device 23. The middle of the cross section of the blade 22 is convex toward the dragging direction, forming a chamfered shape, or an arc shape, or other shape, so that the combined speed of the dragging speed obtained by the gas molecules and the thermal motion speed is consistent with the direction of the groove wall, thereby making full use of the gas The drag speed obtained by the molecule. The blade fixing device 23 should minimize the resistance of the gas in the suction direction. The dynamic seal 21 can be a cylindrical single tow pump static wheel, or a cylindrical single tow pump static wheel, or other dynamic sealing device.

The static wheel 20 is installed in the middle of two moving wheels 1 9 and the dynamic seal 2 1 is installed outside the moving wheel. There is a working gap between the moving and static parts.

When the moving wheel rotates at a high speed, the space 24 between two adjacent stationary wheel blades becomes an extraction groove with two drag surfaces, and the pumped gas is extracted from the upper direction to the lower direction in the axial direction, and is discharged through the air hole 15 at the lower portion of the moving wheel. . Changing the spiral direction of the static wheel blades, or the dragging direction (that is, the rotating direction of the moving wheel) can change the suction direction. If the dragging direction is changed, the tilting direction of the stationary wheel blade is changed accordingly.

Example 5: Horizontal compound disc-type double oblique drag pump

Horizontal composite disc-type double-slant tow pump consists of several sets of disc-type double-slant tow pump suction unit and disc-single tow pump, or cylindrical single-tow pump, or other molecular pump suction unit, or a combination of coaxial installation , And combined in series and parallel. The air intake near the pump is a multi-stage parallel-disc double-slant drag pump suction unit, and the exhaust near the pump is a single drag pump or other molecular pump suction unit.

FIG. 8 is a schematic diagram of a feasible structure. There are several groups in the middle of the pump near the air inlet 25 (three groups are shown in Fig. 8). The disc-shaped double oblique tow pump suction unit 2 is connected in parallel. The moving wheels between adjacent two parallel suction units are connected to the shaft. Air holes, and do not need to be sealed) make up the first suction stage. Several stages are connected in series on both sides (two stages are shown in FIG. 8). The disc-shaped double-slant drag pump pumping unit 26 is a disc-type single-slide drag pump, or the disc-single-slope drag-pump pumping unit 26. The air unit 27 functions as a dynamic seal. Then, two stages are connected in series on each side (two stages are shown in Fig. 8).

The flow direction of the pumped gas is shown by the arrow in FIG. 8, and it enters through the air inlet 25 of the pump, and then passes through the disc-shaped double-slant pump suction unit and the disc-single-slide pump suction unit, or the disc-single-slope-pump suction unit Finally, it is discharged through the exhaust port Π of the pump.

Replacement page (Article 26) FIG. 9 is a schematic diagram of another feasible structure. There are several groups in the middle of the pump near the air inlet 25 (two groups are shown in Fig. 9). The pumping units of the disc-shaped double oblique drag pumps connected in parallel form a first pumping stage, and several stages are connected in series on both sides (Figure 9 One stage is shown) The disc-shaped double oblique tow pump suction unit 26, each disc-shaped double oblique tow pump stage uses a disc single tow pump, or the disc single oblique tow pump suction unit 27 is used as a dynamic seal. Then, a series of stages (four stages are shown in FIG. 9) of the cylindrical single tow pump or the cylindrical single oblique tow pump suction unit 29 are connected in series on both sides.

Example 6: Vertical compound disc-shaped double oblique tow pump

The vertical composite disc-type double-slant pump is composed of several sets of disc-type double-slant pump pumping units and disc single-slide pumps, or cylindrical single-slide pumps, or other molecular pump suction units, or a combination of coaxial installation. , And combined in series and parallel. The air intake near the pump is a disc-shaped multi-pump pumping unit, and the air exhaust near the pump is a single-tow pump or other molecular pump air-suction unit.

Figure 10 is a schematic diagram of a feasible structure. Above the pump, there are several groups close to the air inlet 25 (two groups are shown in FIG. 10). The disc-shaped double oblique drag pump suction unit 26 in parallel constitutes the first suction stage, and then several stages are connected in series (Figure 1 G The first stage is shown in the figure.) The disc-shaped double-slant tow pump pumping unit 26 uses a disc-shaped single-shovel pump, or the disc-single-tow pump suction unit 27 as a dynamic seal. Close to the exhaust port U of the pump, then several stages are connected in series (four stages are shown in Fig. 10). The cylindrical single trailing pump, or the cylindrical single diagonal trailing pump suction unit 29.

The vertical composite disc-shaped double oblique tow pump is close to the air inlet 25, and several stages of turbo molecular pump suction units connected in series can be installed coaxially to further increase the pumping speed of the pump.

Example 7: Vertical compound cylindrical double oblique tow pump

Vertical composite cylindrical double oblique tow pump consists of several sets of cylindrical double oblique tow pump suction units and disc single tow pumps, or cylindrical single tow pumps, or other molecular pump suction units, or a combination of coaxial installation , And combined in series and parallel. The air intake close to the pump is the cylinder double oblique drag pump suction unit. The exhaust port close to the pump is a single drag pump and other molecular pump suction units.

Figure 11 is a schematic diagram of a feasible structure. Above the pump, there are several groups near the air inlet 25 (two groups are shown in Figure 11). The cylindrical double oblique drag pump suction unit in parallel constitutes the first suction stage, and the exhaust port 28 near the pump is connected in series. Several stages (stage 2 is shown in Figure 1) cylindrical single tow pump, or cylindrical single oblique tow pump suction unit 29.

The compound cylindrical double oblique drag pump is close to the pump's air inlet 25. It is also possible to coaxially install several stages of turbomolecular pump pumping units in series pumping to further increase the pumping speed of the pump.

Real drag eight: Optimized structure of the disc-shaped diagonal pump

This actual towing example is similar to the various disc-shaped oblique towing pumps described above.

1. As shown in FIG. 12, the spacer ring 32 between two adjacent moving wheels 31 adopts a claw-shaped structure, such as a plum shape as shown in FIG. 13, or a straight-sided claw-shaped spacer ring as shown in FIG. 14. Therefore, the process performance of the rotor is improved.

Replacement page (by-law 26 糸) If the claw-shaped spacer ring shown in FIG. 14 is used, the outer width of the claw may be smaller than the inner width. If there are air holes 15 on the moving wheel, the number of claws of the claw-shaped spacer ring should be the same as the number of air holes on the moving wheel. The space between two adjacent claws should correspond to the position of the air hole 15. The optimal number of claws (that is, the air holes on the moving wheel) (Number) is 3-5.

2. The optimal value of the static wheel blade groove, or the angle between the blade and the radius is between 50 ° _7 () °. When the linearity of the moving wheel is low, or when the gas is pumped from the inside to the outside, the inside angle should be smaller than the outside angle. When the linear speed of the moving wheel is high, the inside angle should be greater than the outside angle.

Example 9: Disc-shaped double oblique tow pump with optimized structure

This actual drag example is similar to the various disc-shaped double oblique drag pumps described above.

1. As shown in FIG. 15, the static impeller 16 is directly fixed on a fixed ring 33 located on the outer side of the impeller, and no fixing device is used on the inner side of the impeller, thereby improving process performance and air extraction performance.

2. The stationary blade 16 adopts an arc-shaped blade as shown in Fig. 16, which simulates the optimal blade shape and simplifies the blade processing process. Industrial applicability

The invention is mainly used in the fields of vacuum coating, integrated circuit manufacturing, manufacturing of electric vacuum devices such as electric light sources, kinescopes, accelerators and plasma technology.

Replacement page (Article 26)

Claims

Request for Rights

A molecular pump comprising a moving wheel, a stationary wheel, a rotating shaft, a pump casing and the like, characterized in that the pump has at least one set of basic drag molecular pump pumping units, and the pumping slot of the pumping unit adopts a non-rectangular cross section.

2. The molecular pump according to claim 1, characterized in that the cross section of the suction groove of the basic suction unit is inclined or convex toward the dragging direction, so that the combined speed of the dragging speed obtained by the gas molecules and the thermal motion degree Match the direction of the groove wall.

The molecular pump according to claim 2, wherein the basic pumping unit is a disc-shaped single oblique drag pump, the moving wheel of the basic pumping unit is composed of a flat disk, and the static wheel is provided with a plurality of spiral pumps. The disc structure of the air groove is characterized in that the groove wall of the static wheel suction groove is inclined toward the dragging direction, so that the combination of the dragging speed obtained by the gas molecules and the thermal motion speed is consistent with the direction of the groove wall.

The molecular pump according to claim 3, characterized in that a row of short turbine blades is added to the outer side of the moving wheel disc in the basic suction unit of the disc-shaped single oblique drag pump, and the direction of extraction of these short blades and the flow of the gas to be pumped The direction is the same.

5. The molecular pump according to claim 3, characterized in that in the basic suction unit of the disc-shaped single oblique drag pump, the outer and inner thicknesses of the moving wheel disc are thin and the outer and inner thicknesses of the static wheel are thin, and the axial clearances of the moving and static wheels are approximately equal. .

The molecular pump according to claim 3, characterized in that the dynamic and static wheel structures of the basic suction unit of the disc-shaped single oblique drag pump are interchangeable.

The molecular pump according to claim 2, wherein the basic pumping unit is a cylindrical single oblique drag pump, the moving wheel of the basic pumping unit is composed of a cylindrical surface, and the static wheel is provided with a plurality of spiral pumping units. The cylindrical surface of the groove is characterized in that the groove wall of the static wheel suction groove is inclined toward the dragging direction, so that the combined velocity of the dragging degree obtained by the gas molecules and the thermal motion speed is consistent with the direction of the groove wall.

The molecular pump according to claim 7, characterized in that the dynamic and static wheel structures of the basic suction unit of the cylindrical single oblique drag pump are interchangeable.

The molecular pump according to claim 2, wherein the basic pumping unit is a disc-shaped double oblique drag pump, and the moving wheel of the basic pumping unit is composed of two coaxial flat disks, one of which is close to the rotating shaft. There are a number of air holes. The static wheel is composed of several spiral blades and its fixing device. The dynamic seal adopts a disc-shaped single drag pump static wheel or other dynamic sealing device. The static wheel is installed between the two movable wheels. Outside of the moving wheel provided with air holes, the basic suction unit is characterized in that the middle part of the blade section of the static wheel is convex toward the dragging direction, forming a chamfered shape, or an arc shape, or other shapes, so that the drag speed and thermal motion obtained by the gas molecules The resultant velocity of the 逨 degree is consistent with the direction of the groove wall.

1 0. The molecular pump according to claim!), Characterized in that the basic suction unit of the disc-shaped double oblique drag pump

Replacement page (Article 26) A row of short turbine blades is added to the outer side of the middle-moving wheel disc. The extraction direction of these short blades is consistent with the flow direction of the pumped gas.

1 1. The molecular pump according to claim!), Characterized in that in the basic suction unit of the disc-shaped double oblique drag pump, the outer diameter of the moving wheel is thin and the inner thickness is thick, the outer thickness of the static wheel and the dynamic seal is thin, and the dynamic and static wheel shafts The clearances are approximately equal.

1 2. The molecular pump according to claim!), Characterized in that the radial clearance between the moving wheel and the spacer ring in the basic suction unit of the disc-shaped double oblique drag pump is small, and no dynamic seal is required.

13. The molecular pump according to claim 9, characterized in that several groups of disc-shaped double oblique drag pumps and other drag molecular pump suction units, or a combination thereof, are coaxially mounted and combined in a series or parallel manner, The air intake near the pump is a multi-stage, series-connected, disc-shaped double oblique drag pump suction unit, and the exhaust near the pump is another drag molecular pump suction unit.

14. The molecular pump according to claim 13, characterized in that a plurality of sets of disc-shaped double-sloping tow pumps and a plurality of stages of disc-shaped single-sliding tow pumps, or disc-shaped single-sloping tow pumps are coaxially mounted and connected in series and parallel Combination of modes, the inlet of the pump near the pump is a combination of several stages of parallel and series-disc pumping unit, and the exhaust of the pump near the pump is a series of disk-type single tow pumps Pump suction unit.

15. The molecular pump according to claim 13, characterized in that a plurality of sets of disc-shaped double oblique tow pumps and a plurality of stages of cylindrical single tow pumps, or cylindrical single oblique tow pump suction units are coaxially installed, and Combination of serial and parallel modes. The inlet of the pump close to the pump is a series of parallel and series combined pumping units of the disc-shaped double oblique tow pump. The exhaust of the pump is close to the pump. Suction unit for single oblique drag pump.

The molecular pump according to claim 13, characterized in that in the vertical molecular pump structure, several stages of turbomolecular pump pumping units connected in series are added near the air inlet of the pump.

17. The molecular pump according to claim 2, wherein the basic pumping unit is a cylindrical double oblique drag pump, the moving wheel of the basic unit is composed of two coaxial cylindrical surfaces, and the static wheel is composed of a plurality of cylindrical spiral blades. It is composed with a fixed device. The dynamic seal adopts a cylindrical single drag pump static wheel, or other dynamic sealing device. The static wheel is installed between the two movable wheels, and the dynamic seal is installed outside the movable wheel. The basic suction unit is characterized by the section of the static wheel blade. The middle part is convex in the dragging direction, forming a chamfered shape, or an arc shape, or other shape, so that the combined speed of the dragging speed obtained by the gas molecules and the thermal motion speed is consistent with the direction of the groove wall.

The molecular pump according to claim Π, characterized in that several sets of cylindrical double oblique tow pump suction units and several stages of cylindrical single tow pump suction units, or cylindrical single oblique tow pump suction units are coaxially mounted, connected in series. And parallel combination. The air intake near the pump is a cylinder double-slant pumping unit with several stages connected in parallel, and the exhaust port near the pump is a series of single-cylinder tow pumps or a single-cylinder tow pump. Air unit.

19. The vertical molecular pump according to claim 1, characterized in that a plurality of stages of turbomolecular pump suction units connected in series are added near the air inlet of the pump.

Replacement page (Article 26)

The molecular pump according to claim 3, characterized in that the spacer ring between two adjacent moving wheels in the basic suction unit of the disc-shaped single oblique drag pump is a claw-shaped spacer ring.

2 1. The molecular pump according to claim!), Characterized in that the spacer ring between two adjacent moving wheels in the basic suction unit of the disc-shaped double oblique drag pump adopts a claw-shaped spacer ring, and the number of claws of the claw-shaped spacer ring It should be the same as the number of air holes on the moving wheel, and the space between two adjacent claws should correspond to the position of air holes.

22. The molecular pump according to claim 21, wherein the optimal number of claws (that is, the number of air holes on the moving wheel) of the claw-shaped spacer ring between two adjacent moving wheels in the basic suction unit of the disc-shaped double oblique drag pump is 3-5.

23. The molecular pump according to claim 9, characterized in that the stationary vane in the basic suction unit of the disc-shaped double oblique drag pump is fixed on a fixed ring located on the outside of the impeller, and no fixing device is used on the inside of the impeller, so that , Improved process performance and air extraction performance.

24. The molecular pump according to claim 9, characterized in that the optimal value of the included angle between the stationary blade and the radius in the basic suction unit of the disc-shaped double oblique drag pump is between 50 ° and 70 °.

25. The molecular pump according to claim 24, characterized in that the included angle between the stationary blade and the inner radius (the smaller radius) in the basic suction unit of the disc-shaped double oblique drag pump should be smaller than the outer radius (the larger radius). Angle

The molecular pump according to claim 24, characterized in that the stationary blades in the basic pumping unit of the disc-shaped double oblique drag pump adopt arc-shaped blades to simulate the optimal blade shape.

The molecular pump according to claim 25, characterized in that the stationary blades in the basic pumping unit of the disc-shaped double oblique drag pump adopt arc-shaped blades to simulate the optimal blade shape.

Replacement page (Article 26 糸)