JP2002115691A - Turbo-molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo-molecular pump not directly transmitting a shock to an outer casing even when a rotating body is broken. SOLUTION: A fixed blade 1B in at least a first stage turbo mechanism of plural turbo mechanisms is provided with at least one rib 1L in the radial direction. Accordingly, the rib 1L receives a broken piece even if a rotating body 2 is broken and the broken piece flies off outward to prevent a shock from directly transmitting to the casing 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combination of a rotating blade attached to a rotating body integral with a rotating shaft by a motor and driven to rotate, and a fixed blade fixed to a casing opposed to the rotating blade. The present invention relates to a turbo-molecular pump having a plurality of stages of a turbo mechanism comprising:

[0002]

2. Description of the Related Art A turbo-molecular pump exhausts gas by operating a turbo mechanism composed of a combination of a rotating blade and a fixed blade, and its structure is as shown in FIG. This turbo-molecular pump has a fixed part 1F made of, for example, an aluminum alloy and a fixed side mainly composed of a casing 1 and a bearing SB mounted on a holding frame 1M above the center of the fixed part 1F.
And a rotating side mainly composed of a rotating shaft 5 rotatably supported by a motor M and rotationally driven by a motor M, and a rotating body 2 integrally connected to the rotating shaft 5. A rotor 2B is attached to the outer periphery of the rotor 2 in a protruding manner. On the other hand, on the inner periphery of the casing 1, ring-shaped spacers 1S are provided in a laminated manner, and a base end is held between the spacers 1S, and fixed wings 1B projecting inward are provided. . The rotating wing 2B and the fixed wing 1
The combination with B constitutes a turbo mechanism T.
The operation of the turbo mechanism T, that is, the rotor 2B
By the high-speed rotation of the side, the gas molecules sucked from the intake port 3 are beaten off by the turbo mechanism T, and compressed and exhausted toward the exhaust port 4.

Further, at the end of the rotating body 2 on the side of the exhaust port 4, a rotating cylindrical portion 2 D is extended, and the rotating cylindrical portion 2 D is fixed to the fixed cylindrical portion 1 D fixed to the casing 1. It is close to the inner peripheral surface. Further, the fixed cylindrical portion 1
As shown by a two-dot chain line, a spiral groove 1N is engraved on the inner peripheral surface of D. In addition, a cooperation between the spiral groove 1N and the rotating cylindrical portion 2D constitutes a molecular drag pump that performs an exhaust function by viscous flow. Thus, a turbo molecular pump in which the turbo mechanism and the molecular drag pump are combined is referred to as a hybrid turbo molecular pump. B is a vent for connecting the exhaust port 4 to an exhaust pipe (not shown).

[0004] The rotating body 2 is also made of a metal material such as an aluminum alloy in order to withstand high-speed rotation. In the case of the illustrated example, a rotating shaft 5 integrated with the rotating body 2 is used.
Is supported on the holding frame 1M by radial and thrust bearings SB arranged in a pair at the top and bottom.

Incidentally, the motor M is composed of the rotating shaft 5 and the holding frame 1.
M, specifically, as shown in FIG. 6, a rotor winding is attached to the rotating shaft 5, while the inner circumferential surface on the side of the holding frame 1M is provided on the rotating shaft 5 as shown in FIG. An armature winding is provided and configured by a combination of both.
With this high-frequency motor M, the rotating body 2 is driven at a speed of 20 / min.
It is rotationally driven at 000 to 100,000 rotations.

[0006]

In such a turbo-molecular pump, the material constituting the rotating body 2 has a defect, or the material of the rotating body 2 is gradually corroded by exhaust of corrosive gas or the like. During repeated use, the strength may decrease and the rotating body 2 may be damaged by centrifugal force due to high-speed rotation. When the breakage occurs, the rotating body 2 is unbalanced. Even if the unbalance is small, the rotating energy such as vibration is transmitted to the casing 1 via the bearing SB because of high-speed rotation. To generate torque. Then, a fixing tool such as a bolt fixing the turbo-molecular pump is broken, and a large impact is given to the exhaust device, which is dangerous.

[0007] The main part and parts of the rotating body 2 ruptured due to damage collide with the fixed wing 1 B and give an impact to the casing 1. This impact is large because of high-speed rotation, and therefore, in order to reduce the destruction of the entire turbo-molecular pump due to the impact, it is necessary to strengthen the casing 1 and the like, and there is a problem that the size and weight must be increased. An object of the present invention is to provide a turbo molecular pump that solves such a problem.

[0008]

In order to solve the above-mentioned problems, a turbo-molecular pump provided by the present invention is a turbo-molecular pump having a multi-stage turbo mechanism. At least one rib is provided in the radial direction.
Further, according to the present invention, a fixed cylindrical portion is provided on a fixed side surrounding the rotating body, and the fixed cylindrical portion is constituted by a double cylinder, and a means is provided between the two to alleviate an impact caused by damage to the rotating body. It is like that. Therefore, the fixed blade in the turbo-molecular pump is reinforced, the strength of the turbo mechanism is improved, and the impact on the fixed cylindrical portion is reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 shows the configuration of a turbo-molecular pump provided first by the present invention. FIG. 1 is a view showing the entire turbo-molecular pump in a longitudinal section, similarly to FIG.
The components and parts denoted by the same reference numerals as in FIG. 6 are the same as those in FIG. 6, and detailed description thereof will be omitted.

According to the present invention, at least one turbo mechanism T
Is characterized in that at least one rib 1L is provided in the radial direction in the fixed blade 1B of
Is a rib having a constant thickness, as shown in FIG. 2, and the mechanical strength of the entire fixed blade 1B is increased. FIG.
Shows a part (half) of the one-stage fixed blade 1B, but two ribs 1L are provided at 180 ° intervals. Therefore, the mechanical strength of the fixed wing 1B in the radial direction is enhanced, and even if the rotating body 2 is damaged and its parts or the like collide, the rib 1L receives it, or the fixed wing 1B
B is received with the strength of the whole, and the influence on the casing 1 and the like is reduced.

A turbo-molecular pump provided secondly by the present invention comprises a fixed side, in particular, a fixed cylindrical side of a thread groove pump mechanism in a hybrid type turbo-molecular pump, which is formed into a multi-split type.
The impact at the time of breakage of the rotating body 2 is to be absorbed by the fixed-side multi-split body. Specifically, the fixed cylindrical portion 1D is configured as a divided fixed cylindrical portion 7 divided into a plurality of portions, and FIG. 3 is a diagram illustrating an example in which the fixed cylindrical portion 1D is divided into two. FIG. 3 is a view of the fixed cylindrical portion 7 viewed from above.
In the figure, a fixed cylindrical portion 7 is divided into two upper and lower semicircular members 7U and 7D along a horizontal line, and 6 is a bolt for joining and fixing these two members. Therefore, when the rotating body 2 is damaged and fragments thereof collide with the fixed cylindrical portion 7, the two members 7U and 7D of the fixed cylindrical portion 7 tend to expand with the energy. At this time, a sudden pulling force acts on the bolt 6, and the bolt 6 is broken. Energy due to breakage of the rotating body 2 is consumed for breaking the bolt 6,
The impact on the casing 1 and the like can be reduced.
As a method of dividing the fixed cylindrical portion 7, it is also possible to adopt a shape divided into three in the radial direction or a shape divided into four. desirable. Two or three fixing bolts 6 are arranged in the axial direction, and their material and size (diameter and the like) are set to absorb impact.

Further, in the turbo-molecular pump provided by the present invention, the fixed cylindrical portion is formed in a double ring structure, and a shock when the rotating body 2 is damaged is absorbed by a combination of the double ring structure. It is. There are three methods for combining the double ring structures. The first method is to join the double rings on a conical surface, the second method is to minimize the mutual contact area of the double rings, and the third method is to make the double rings A cushioning material is interposed between them.

Hereinafter, these systems will be described. First, FIGS. 4 and 5 show examples in which the mutually joined surfaces of the double ring structure are formed as conical surfaces. That is, in both figures, 1U is an inner fixed cylindrical portion and 1R is an outer fixed cylindrical portion, and the joint surfaces of the fixed cylindrical portions 1U and 1R are formed by conical surfaces CF. . This conical surface C
According to the joining of the two fixed cylindrical portions 1U, 1R by F, when the rotating body 2 is damaged and the broken piece collides with the inner fixed cylindrical portion 1U, the impact force is divided at the conical surface CF. And transmitted to the outer fixed cylindrical portion 1R. The component force depends on the inclination angle of the conical surface CF, but is reduced as far as the component force.

Next, in the second system, the contact area of each other is minimized. As shown in FIG. 4, a plurality of concave portions 1K are formed in the inner fixed cylindrical portion 1U.
The concave portion 1K is formed on the outer peripheral conical surface, and is formed as an annular concave portion 1K. Since the plurality of concave portions 1K are connected, the convex portion 1S of the fixed cylindrical portion 1U therebetween is joined to the outer fixed cylindrical portion 1R. Therefore, when an impact is generated due to the breakage of the rotating body 2, the impact is reduced by crushing (crushing) of the convex portion 1S, that is, the portion where the contact surface is reduced.

[0015] Then, the third fixed cylindrical portion 1 is used.
As shown in FIG. 5, the two fixed cylindrical portions 1U and 1R are formed as conical surfaces, while the corresponding surfaces are formed as conical surfaces. And a flexible member G such as a rubber material or a spring material is interposed (press-fitted) therebetween. By the intervention of the flexible member G, the impact force applied to the inner fixed cylindrical portion 1U is reduced. Since the turbo molecular pump provided by the present invention is as described above, the impact energy due to the breakage of the rotating body is absorbed by the rib 1L of the fixed blade 1B and the fixed cylindrical portion 1D, and the impact on the casing 1 and the like is greatly reduced. Will be.

The turbo-molecular pump provided by the present invention is as described in detail above, but is not limited to the above and illustrated examples, but includes various modified embodiments. First, a rib 1L is attached to the fixed blade 1B of the turbo mechanism T in at least one of the stages of the turbo mechanism T having a plurality of stages.
In the present invention, at least one rib 1L is provided in the radial direction, and two ribs are provided in the illustrated example.
It is conceivable to increase the strength by setting three pieces every 120 angles or four pieces every 90 angles. Further, such ribs may be provided in two or three steps.

Also, various modifications can be given to the case where the fixed cylindrical portion 1D receives a shock due to the damage of the rotating body 2. This fixed cylindrical portion 1D is effective in the case of a hybrid type turbo-molecular pump as shown in the figure, but is also applicable to a turbo-molecular pump having a fixed cylindrical portion 1D which does not constitute a thread groove pump mechanism. . In this case, the fixed cylindrical portion 1D is provided only for receiving an impact due to the damage of the rotating body 2. Further, there can be mentioned a modification of the shape of the fixed wing constituting the turbo mechanism. That is, in the illustrated example, the fixed wing is an example in which a ring is attached to the inner end side of the wing as shown in FIG. 2, but the inner end of the wing is open and a fixed ring is attached to the outer end side. The present invention is also applicable to a turbo-molecular pump of a type in which the fixing ring is attached between the spacers. In this case, the ribs extend inward from the outer fixing ring.

As described above, the type and configuration of the turbo-molecular pump can be applied to various types and configurations of turbo-molecular pumps, regardless of the gist of the present invention. Therefore, for example, the illustrated example is a hybrid type turbo-molecular pump, but the present invention can be applied to a turbo-molecular pump having only a turbo function. The present invention is also applicable to a turbo-molecular pump that supports the rotating body 2 with a magnetic bearing. The invention embraces all these alternative embodiments.

[0019]

The turbo-molecular pump provided by the present invention is as described in detail above, so that the impact when the rotor blades are broken is moderated and transmitted to the pump casing, and the pump mounting structure is reduced in size and size. can do. There is no need to provide a breaking member for the rotating body, that is, a special structure for blocking the metal lump, and the pump can be miniaturized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a turbo-molecular pump according to the present invention.

FIG. 2 is a perspective view showing a fixed blade in the turbo-molecular pump according to the present invention.

FIG. 3 is a diagram showing a configuration of a fixing member of the turbo-molecular pump according to the present invention.

FIG. 4 is a diagram showing a configuration of a fixed cylindrical portion in a turbo-molecular pump according to the present invention.

FIG. 5 is a view showing another configuration of the fixed cylindrical portion in the turbo-molecular pump according to the present invention.

FIG. 6 is a diagram showing a bearing configuration of a conventional turbo-molecular pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Casing 1B ... Fixed wing 1D ... Fixed cylindrical part 1U ... Inner fixed cylindrical part 1R ... Outer fixed cylindrical part 1K ... Concave part 1L ... Rib 1S ... Convex part CF ... Conical surface 2 ... Rotating body 2B ... Rotation Airfoil 2D: Rotating cylindrical part 3: Inlet port 4: Exhaust port 5: Rotating shaft 7: Fixed cylindrical part of split type T: Turbo mechanism

Claims (5)

[Claims] 1. A multi-stage turbo mechanism comprising a combination of fixed blades and rotating blades installed on the inner periphery of a casing, and a rotating shaft integral with a rotating body provided with the rotating blades is integrated with the casing. In a turbo-molecular pump that is rotatably supported via a bearing with respect to a fixed portion and is driven to rotate by a motor to exhaust molecules from an intake port of a casing to an exhaust port, the fixed blade has at least one stage. And at least one rib is provided in the radial direction. 2. A multi-stage turbo mechanism comprising a combination of fixed blades and rotating blades installed on the inner periphery of a casing, and a rotating shaft integral with a rotating body provided with the rotating blades is integrated with the casing. A pump that is rotatably supported by bearings on a fixed portion of the casing and is driven to rotate by a motor, thereby exhausting molecules from an intake port of the casing to an exhaust port. In a turbo-molecular pump in which a fixed cylindrical portion is provided and a thread groove pump mechanism is provided between an inner peripheral surface of the fixed cylindrical portion and an outer peripheral surface of the rotating body, the fixed cylindrical portion is composed of a plurality of members. A turbo-molecular pump, which is configured as a divided body and includes a connecting tool for connecting each member. 3. A multi-stage turbo mechanism comprising a combination of fixed blades and rotating blades installed on the inner periphery of a casing, and a rotating shaft integral with a rotating body provided with the rotating blades is integrated with the casing. A pump that is rotatably supported via a bearing with respect to a fixed portion of the casing, and the rotating shaft is rotationally driven by a motor to exhaust molecules from an intake port of a casing to an exhaust port. In a turbo-molecular pump in which a fixed cylindrical portion is provided on the exhaust port side and a thread groove pump mechanism is provided between the inner peripheral surface of the fixed cylindrical portion and the outer peripheral surface of the rotating body, the fixed cylindrical portion is doubled. A turbo-molecular pump comprising a cylinder, wherein a concave portion is formed on at least one peripheral surface of the two cylinders in contact with each other to reduce the contact area between the cylinders. 4. A multi-stage turbo mechanism comprising a combination of fixed blades and rotating blades installed on the inner periphery of a casing, and a rotating shaft integral with a rotating body provided with the rotating blades is integrated with the casing. A pump that is rotatably supported via a bearing with respect to a fixed portion of the casing, and the rotating shaft is rotationally driven by a motor to exhaust molecules from an intake port of a casing to an exhaust port. In a turbo-molecular pump in which a fixed cylindrical portion is provided on the exhaust port side and a thread groove pump mechanism is provided between the inner peripheral surface of the fixed cylindrical portion and the outer peripheral surface of the rotating body, the fixed cylindrical portion is doubled. A turbo-molecular pump comprising a cylinder and a flexible member inserted between the cylinders. 5. A multi-stage turbo mechanism comprising a combination of a fixed wing and a rotary wing installed on the inner periphery of a casing, and a rotary shaft integral with a rotary body provided with the rotary wing is integrated with the casing. A pump that is rotatably supported via a bearing with respect to a fixed portion of the casing, and the rotating shaft is rotationally driven by a motor to exhaust molecules from an intake port of a casing to an exhaust port. In a turbo-molecular pump in which a fixed cylindrical portion is provided on the exhaust port side and a thread groove pump mechanism is provided between the inner peripheral surface of the fixed cylindrical portion and the outer peripheral surface of the rotating body, the fixed cylindrical portion is doubled. A turbo-molecular pump comprising a cylinder, wherein the corresponding surfaces of the two cylinders are formed in a conical shape.