JPH05106562A - Traveling wave tube wall type vacuum pump - Google Patents

Abstract

PURPOSE:To provide a vacuum pump with no use of any oil, which excels in the durability and exhausts gas certainly. CONSTITUTION:An outer tube 2 made of resilient material is fitted by pressure on a fixed shaft 1 in cylindrical or columnar form, and outside of this tube 2 a number of working members 3 are furnished which are to expand or shrink the same 2 in undulation progressing in the axial direction, and a space is formed progressing in undulate form in the axial direction between the outer tube 2 and fixed shaft 1 through the action of these working members 3, and gas is transported through this space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry vacuum pump which does not use an oil seal and which is used for manufacturing semiconductors and the like.

[0002]

2. Description of the Related Art Conventionally, dry vacuum pumps that can be compressed to atmospheric pressure without using an oil seal are roughly classified into rotary type and reciprocating type, and the former rotary type is a vortex type or centrifugal type that rotates at high speed and screw type. There is a groove type, and there are roots type and claw type that rotate at low speed. The latter reciprocating type is known as a piston type or a diaphragm type.

On the other hand, a peristaltic pump using an elastic body is one in which the elastic body is pressed and deformed into a corrugated shape as shown in FIG. 5, or a corrugated elastic body is opposed as shown in FIG. 7 as shown in FIG. There is a type in which the inner surface is pressed and deformed so that the inner surface contacts.

[0004]

However, in the above-mentioned rotary type, it is necessary to reduce the gap between the rotary body and the fixed wall, and it is difficult to improve the processing accuracy thereof. Since a large number of steps are provided in the axial direction of the rotating body, accidents where the rotating body comes into contact with the fixed wall due to thermal expansion during rotation tend to occur, while the low-speed rotating type has a complicated rotating body shape. There was a problem in terms of processing accuracy.

Further, since the reciprocating type has a valve for intake and exhaust, there is a problem that the durability of the valve or the sliding surface of the piston and the cylinder or the diaphragm is unreliable.

The peristaltic pump shown in FIG. 5 has a large backflow of gas and is difficult to apply to a high vacuum pump. Further, the peristaltic pump shown in FIG. 6 can exhaust gas. When pressed in the direction of arrow F of Fig. 7, a gap a is generated at both ends of the opening, and when the elastic body is pressed with a large pressure to reduce this gap, a crack is generated on the side surface of the elastic body during long-term use and gas is generated. It had problems such as leaking.

An object of the present invention is to solve these problems and to provide a traveling wave tube wall type dry vacuum pump having excellent durability and capable of reliably discharging gas.

[0008]

In order to achieve the above object, the present invention is such that an outer tube made of an elastic material is press-fitted to the outer periphery of a cylindrical or cylindrical fixed shaft, and the outer tube is provided with an outer tube. The present invention is characterized in that a large number of actuating members for expanding or contracting the outer tube in a wave shape that advances in the axial direction are arranged.

[0009]

When the actuating member is subjected to the expansion and contraction of the corrugation advancing in the axial direction, the outer tube is deformed into the corrugation advancing in the axial direction, thus the axial length between the outer tube and the fixed shaft. A corrugated space advancing in the direction is formed to transfer the gas in the axial direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a fixed shaft made of a cylindrical or cylindrical aluminum material or the like, and the fixed shaft 1 is formed in a linear shape.

Reference numeral 2 denotes an outer tube, which is made of a synthetic resin, synthetic rubber or an elastic metal plate such as an ultrathin plate, and has the fixed shaft 1
Is crimped onto the outer periphery of the.

Reference numeral 3 denotes an actuating member, which is composed of, for example, a piezoelectric actuator, the inner end 3a of which is fixed to the outer surface of the outer tube 2 as shown in FIG. distance l ₁ of, l ₂ ... while being arranged with a l _n, the outer end 3b is the fixed shaft 1 is concentric with the outer casing 4
Is fixed to the inner surface 4a of the.

5 ... 5 are the piezoelectric actuators 3 ... 3
The input line that activates is shown.

Next, the operation of the embodiment having the above structure will be described.

When a sine wave voltage whose phase is advanced in the axial direction is applied to each piezoelectric actuator 3, the outer tube 2 is transformed into a waveform that advances in the axial direction,
Thus, a corrugated space that advances in the axial direction is formed between the outer tube 2 and the fixed shaft 1 to transfer gas in the axial direction and exhaust it.

Next, the pumping speed will be calculated with reference to FIG.

That is, the amplitude of the outer tube is a (m), the traveling wave propagation velocity is V ( ^m / _s ), the wavelength is L (m), and the radius of the fixed axis is R.
(M), the exhaust speed S (m ³ / _s ) is S = 2πaRV
Indicated by.

Therefore, for example, V = 10 ( ^m / _s ) and R = 5 × 10
^-2 (m), a = 0.1 × 10 ^-3 (m), S = 0.0003
To become _{^{(m 3 / s) = 0.3}} (L / s).

When the frequency of the wave is f (H _Z ), f = ^V / _L , and when L = 0.1 (m), the frequency is 100 H _Z.

FIG. 4 shows a second embodiment of the present invention in which the outer tube 2 is a magnetic thin iron plate having elasticity and the operating member 3 is formed by electromagnetic coils 6 ... Edge 6
Reference character a denotes the outer tube 2 and a gap t, and the outer end 6b is fixed to the housing 4.

By applying a sinusoidal voltage whose phase is advanced in the axial direction to the electromagnetic coils 6 ... 6, the attractive force of the electromagnetic coils 6 ... 6 is increased or decreased in a sinusoidal shape whose phase is advanced in the axial direction. The outer tube 2 can be displaced in a wave shape that advances in the axial direction.

The actuating member 3 may be a piezoelectric actuator, an electromagnetic coil, or a member that actuates mechanically or electrically.

[0024]

As described above, according to the present invention, an outer tube made of an elastic material is crimp-fitted to the outer periphery of the fixed shaft, and the outer tube is corrugated so that the outer tube travels in the axial direction. Since a large number of actuating members for expanding or contracting are provided in the space, a corrugated space that advances in the axial direction is formed between the outer tube and the fixed shaft, and the gas can be transferred by the space. It is possible to obtain a dry type vacuum pump having excellent durability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an explanatory diagram illustrating a pump action of the vacuum pump of the present invention.

FIG. 4 is a sectional view showing a basic configuration of another embodiment of the present invention.

[Figure 5]

FIG. 6 is a sectional view showing the principle of a conventional peristaltic pump.

7 is a sectional view taken along the line VII-VII of FIG.

[Explanation of symbols]

 1 Fixed shaft 2 Outer tube 3 Operating member 4 Outer casing

Claims (3)

[Claims] 1. An outer tube made of an elastic material is press-fitted onto the outer periphery of a cylindrical or columnar fixed shaft, and the outer tube is expanded or contracted outside the outer tube in a wave shape that advances in the axial direction. A traveling wave tube wall type vacuum pump having a large number of actuating members. 2. The actuating member comprises a piezoelectric actuator, the inner end of which is fixed to the outer surface of the outer tube, and the outer end of which is fixed to the inner surface of a tubular outer casing of the outer tube, The traveling wave tube wall type vacuum pump according to claim 1, wherein sinusoidal wave voltages having different phases are sequentially applied to the actuating member in the axial direction. 3. The outer tube is formed of a magnetic thin-walled material and the actuating member is formed of an electromagnet, and the outer end of the actuating member is fixed to an outer cylindrical outer casing of the outer tube. 2. The process according to claim 1, wherein the end is formed so as to have a predetermined distance from the outer surface of the outer tube, and sinusoidal voltages having different phases are sequentially applied to the actuating member in the axial direction. Wave tube wall type vacuum pump.