JPS6143559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a stator (stationary vane) in a molecular pump, which is a type of vacuum pump.

The structure of a conventional stator will be explained with reference to FIGS. 1 to 4. Figure 1 is a longitudinal sectional view of a vertical molecular pump, Figure 2 is a sectional view of a combination blade, Figures 3 and 4 are graphs showing the relationship between maximum pumping speed efficiency and maximum compression ratio depending on blade shape, and Figure 5 The figure is a plan view showing an example of a conventional stator, FIG. 6 is a perspective view as seen from section A in FIG. 5, and FIG. 7 is a perspective view from B in FIG. 5. In FIG. 1, the structure of the molecular pump is such that a rotor 2 (rotary blades) and a motor 5 constitute a driving section, a stator 3 (stator blades) is inserted between the blades of the rotor 2, and a stator 3 is fixed. A spacer ring 4 is provided, and an outer cylindrical case 1 is provided outside the spacer ring 4 to fix the entire body. Fluid enters from above and is exhausted from below. Next, in FIG. 2, the relationship between the rotor 2 and the stator 3 is alternately provided so that the angles of the respective blades are opposite to each other. The performance of the molecular pump is determined by the relationship between the pitch chord ratio S ₀ =a/b and the blade angle α.
Therefore, the design method for molecular pump blades is as follows:
When installing several stages of blades, it is common practice to increase the exhaust speed efficiency on the intake side to improve the passage of molecules, and on the exhaust side to increase the compression ratio than the exhaust speed efficiency to increase the degree of vacuum. It is. Therefore, as shown in Figures 3 and 4, it is recommended to select S ₀ = around 1.0 to improve pumping speed efficiency, and to choose S ₀ = around 0.5 to improve compression ratio. Recognize. Additionally, it is a well-known fact that it is effective to set the blade angle to α = 30 to 40 degrees to increase exhaust velocity efficiency, and to α = 10 to 20 degrees to increase compression ratio. . Therefore, the shape of the blade arrangement is gradually changed from the intake side S ₀ = 1.0 and blade angle α = 30 to 40°, and the exhaust port side S ₀ = 0.5 and blade angle α = 10 to 20°. It is more effective. FIG. 4 shows the shape of a general stator, in which blades are formed by making cuts in a single disc serving as the stator member and bending the disc. Pitch cord ratio S ₀ and blade angle α can be adjusted freely by machining.
It can be manufactured at. However, since the stator 3 has a thin plate and a large number of blades, it is difficult and time consuming to process the stator while changing the pitch cord ratio S ₀ and the blade angle α. It becomes expensive. Therefore, a good method is to bend the plate, but if S ₀ and α are gradually changed as described above, there is a limit because it is made from a single plate, and the final It has the disadvantage that it is impossible to manufacture one with a typical value of S ₀ =0.5 and α = 10 to 20°. Furthermore, when using a large number of blades, there is a drawback that the work is difficult regardless of the pitch cord ratio S ₀ and the blade angle α.

In view of the above points, the present invention provides stator blades manufactured by plate bending work with a predetermined pitch cord ratio S ₀
The object of the present invention is to provide a stator structure that allows the blade angle α to be easily formed.

In the present invention, the stator of a molecular pump is formed by bending one stator member with the same blade angle and blade spacing, and forming the other stator member with the same blade angle and blade spacing as one of the blades of the other stator member. By bending and forming the other blade and arranging the other blade of the other stator member between the blades of the other stator member, the predetermined pitch cord ratio when manufacturing the stator of the molecular pump can be achieved. and the blade angle can be easily formed.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 8 to 12. As shown in FIGS. 8 and 9, first, a notch for the wing is made in a disc serving as a base material. In other words, cutouts are made in the corresponding discs at positions that will become the blade roots in opposite directions as shown by diagonal lines, and the plates are bent in the same direction in the same way as the stator shown in Figure 5 to create the blade shape. One stator member 6 and the other stator member 7 are manufactured. That is, in one stator member 6, one blade is bent and formed with the same blade angle and blade spacing, and in the other stator member 7, the other blade is bent and formed with the same blade angle and blade spacing as one blade in one stator member 6. The wings are formed by bending. Next, as shown in FIG. 10, one stator member 6 and the other stator member 7 are placed one on top of the other so that the notches at the bases face each other, and one stator member 6 and the other stator member 7 are rotated relative to each other. , 1st
A combined stator is formed as shown in FIGS. 1 and 12. In this case, the other wing of the other stator member 7 is arranged between one wing of the one stator member 6 . By doing as in this embodiment, the distance between one blade of one stator member 6 and the other blade of the other stator member 7 adjacent to this blade, that is, the blade pitch 2, is reduced to half of the conventional one-piece blade. Therefore, it is possible to easily obtain the value of the theoretical pitch code ratio S ₀ necessary to increase the compression ratio. Furthermore, the stator members 6 and 7 can also form a combined stator, so that the stator member 1
Since the number of blades per blade is smaller than that of conventional blades, it has the effect of making plate bending work easier. Furthermore, the reduction in strength due to the notch at the base of the blade is not a problem at all since this product is a stationary blade.

As described above, according to the present invention, the number of blades in each stator member is reduced and the spacing between the blades is wide, making it easy to manufacture and making it possible to form a predetermined pitch cord ratio and blade angle.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of a vertical molecular pump, Figure 2 is a sectional view of a combination blade, Figures 3 and 4 are graphs showing the maximum pumping speed efficiency and maximum compression ratio depending on the blade shape, and Figure 5 is a graph showing the maximum pumping speed efficiency and maximum compression ratio depending on the blade shape. A plan view of a conventional stator, FIG. 6 is a perspective view from part A in FIG. 5, FIG. 7 is a view from B in FIG. 5, and FIGS. 8 and 9 are an embodiment of the stator according to the present invention. FIG. 10 is a partially enlarged plan view of an embodiment of the stator according to the present invention, FIG. 11 is a perspective view taken from section C in FIG. 10, and FIG. This is a view from D. 1... Outer cylinder case, 2... Rotor, 3... Stator,
6... One stator member, 7... Other stator member, 4... Spacer ring, 5... Motor.

Claims (1)

[Claims] 1 Bending and forming one blade on one stator member with the same blade angle and blade spacing, bending and forming the other blade on the other stator member with the same blade angle and blade spacing, and forming a blade between the one blade. A stator for a molecular pump, characterized in that the other blade is disposed on the stator of the molecular pump.