JPH08284877A - Vacuum pump - Google Patents

Abstract

PURPOSE: To provide a vacuum pump that is able to efficiently exhaust in a wide pressure range, and simple in structure. CONSTITUTION: A magnetic coupling part 9 is installed in space between a turbo-molecular pump part 3 and a thread groove pump part 2 as a sliding mechanism. This magnetic coupling part 9 consists of both first and second magnetic bodies 900 and 901, and both these pump parts 3 and 2 are magnetically joined in noncontact by dint of the magnetic attraction. In the case where excessive load exceeding this joining force (magnetic attraction) acts on the turbo-molecular pump part 3, a slide conformed to the extent of load is produced in an interval between both these pump parts 2 and 3 and thereby the thread groove pump part 2 alone is rotated, so such a nonconformity (a drop in rotational frequency and generation of heat) that the turbo-molecular pump part 3 alone remains rotated as receiving the excessive load is made to be prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump which can efficiently exhaust gas in a wide pressure range and has a simple structure.

[0002]

2. Description of the Related Art Conventionally, there have been turbo molecular pumps, screw groove pumps, scroll pumps, drag pumps, etc. as vacuum pumps. In particular, turbo molecular pumps have rotor blades on the outer peripheral surface of a rotor. It is known that the outer peripheral surface of the rotor is provided with a threaded portion.

As shown in FIG. 8, the turbo molecular pump has a characteristic that the exhaust efficiency is high on the high vacuum side, and the screw groove pump, the scroll pump and the drag pump have a characteristic that the exhaust efficiency is good on the low vacuum side as shown in FIG.

Further, as a vacuum pump developed from the viewpoint of enabling a wide range of evacuation from low vacuum to high vacuum region, for example, a so-called wide band type composite pump which is a combination of the above turbo molecular pump and a thread groove pump is also available. Are known.

Regarding this kind of wide band type composite pump,
As shown in FIG. 10A, a structure in which both the rotary blade a and the screw portion b are simultaneously rotated by one drive shaft 50, FIG.
Two drive shafts 51 and 52 that rotate independently as shown in FIG.
The rotating blade a and the screw portion b are rotated separately by the above, or a separating mechanism 53 for separating the rotating blade a side from the screw portion b side is provided as shown in FIG. There is a structure in which both rotation of the rotary blade a and the screw portion b and rotation of only the screw portion b can be appropriately selected by the shaft 54.

[0006]

However, the conventional broadband type composite pump has the following problems.

According to the configuration shown in FIG. 10 (a), both the rotor blade a and the screw portion b rotate at the same time. Therefore, on the low vacuum side, the turbo molecular pump portion (rotor blade a) is rotated.
1) because the load received by the
As indicated by the dotted line 1 (b), the rotation speed is reduced and heat is generated, the original performance of the thread groove pump section (the section with the thread section b) is not exhibited, exhaust efficiency is poor, and the pressure at which exhaust operation is possible. The band becomes narrower (see the solid line in FIG. 11A).

From the viewpoint of preventing a decrease in the number of rotations, if the motor required for the rotation is made large, there is a problem that the power consumption increases accordingly.

The configurations shown in FIGS. 10 (b) and 10 (c) both enable independent rotation of the turbo-molecular pump section and the thread groove pump section, and therefore avoid the above-mentioned problems. However, the structure has the following drawbacks.

That is, in the structure shown in FIG. 10 (b), since the independent rotation of the turbo molecular pump section and the thread groove pump section is caused by the two drive shafts 51 and 52,
Not only a plurality of drive shafts are required, but also a deceleration mechanism for the drive shafts, a plurality of controllers and the like are required, which makes the entire device complicated.

On the other hand, in the structure shown in FIG. 10 (c), since such an independent rotation is caused by the separating mechanism 53, the structure of the separation is complicated,
This also complicates the entire device.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a vacuum pump which can efficiently exhaust gas in a wide pressure range and has a simple structure.

[0013]

According to a first aspect of the present invention, gas is exhausted by rotation in a constant pressure zone, and
A first rotary pump part having a blade part or a screw part for exhausting the gas, and a gas for exhausting gas by rotation in a pressure range different from that of the first rotary pump part, and a blade for exhausting the gas. And a second rotary pump part including a screw part, and the first rotary pump part and the second rotary pump part are provided with a slip mechanism in which slip occurs depending on a load acting on the rotary pump part. It is characterized by being joined through.

According to a second aspect of the present invention, the first rotary pump portion includes a screw pump rotor formed of a cylindrical body rotatably arranged, and a screw portion provided on an outer peripheral surface of the screw pump rotor. The second rotary pump unit is characterized by including a turbo pump rotor formed of a cylindrical body rotatably arranged, and a blade portion provided on the outer peripheral surface side of the turbo pump rotor.

According to a third aspect of the invention, the sliding mechanism has a first structure.
The rotary pump unit and the second rotary pump unit are magnetically coupled to each other in a non-contact manner.

According to a fourth aspect of the present invention, the magnetic coupling section is located between the first rotary pump section and the second rotary pump section and is attached to the first rotary pump section side. And a second magnet body facing the first magnet body and attached to the second rotary pump portion side.

The invention according to claim 5 is characterized in that the first and second magnet bodies are made of permanent magnets.

According to a sixth aspect of the present invention, one of the first and second magnet bodies is an electromagnet.

According to a seventh aspect of the invention, the sliding mechanism is the first
Located between the rotary pump part and the second rotary pump part of
A first contact portion provided on the first rotary pump portion side and a second contact portion slidably contacting the first contact portion and provided on the second rotary pump portion side. It consists of and.

The invention according to claim 8 is characterized in that the sliding mechanism is the first
Between the rotary pump part and the second rotary pump part, a magnetic fluid in contact with the both pump parts is provided.

[0021]

According to the present invention, in the pressure range where an excessive load acts on either the first or second pump section, slippage occurs between the rotary pump sections depending on the load, and rotation on the side receiving the load occurs. The rotation of the pump part stops.

[0022]

Embodiments of the vacuum pump according to the present invention will be described in detail below with reference to FIGS.

As shown in FIG. 1, this vacuum pump has a thread groove pump section 2 as a first rotary pump section and a turbo molecular pump section 3 as a second rotary pump section in a casing 1.

The thread groove pump portion 2 is composed of a thread pump rotor 200 and a thread portion 201 which are cylindrical, and the thread pump rotor 200 is integrally provided on the shaft portion 4 located inside thereof and the shaft portion 4 is provided. The screw portion 201 is formed on the outer peripheral surface of the screw pump rotor 200.

Inside the screw pump rotor 200, the shaft portion 4 is provided.
The stator 5 is provided at a position facing the outer peripheral surface of the stator 5, and the stator 600 of the motor 6 is installed on the stator 5.
A rotor 601 of the motor 6 is arranged on the shaft 4 at a position facing the stator 600.

On the other hand, the turbo molecular pump portion 3 is arranged in series with the thread groove pump portion 2 and is composed of a turbo pump rotor 300 and a blade portion 301 which are cylindrical bodies.

The turbo pump rotor 300 is rotatably attached to the inner shaft portion 7 via bearings 8 and 8. The shaft portion 7 is located on an extension line of the shaft portion 4 of the thread groove pump portion 2. In addition, one end is integrally fixed to the end surface of the screw pump rotor 200.

The blade portion 301 is provided on the outer peripheral surface side of the turbo pump rotor 300 and is composed of a plurality of rotary blades 301a and fixed blades 301b. The rotary blades 301a and fixed blades 301b are the center of rotation of the turbo pump rotor 300. The rotor blades 301a are alternately arranged along the axis, and the rotor blades 301a are integrally formed on the outer peripheral surface of the turbo pump rotor 300, and the rotor blades 301a are fixed blades 301b.
Is integrally provided on the inner wall surface of the casing 1.

Turbo molecular pump section 3 and thread groove pump section 2
A magnetic coupling portion 9 is provided as a sliding mechanism between the magnetic coupling portion 9 and the first and second magnetic coupling portions 9.
It is composed of magnet bodies 900 and 901.

The first magnet body 900 is located between the thread groove pump portion 2 and the turbo molecular pump portion 3 and is attached to the thread groove pump portion 2 side, while the second magnet body 90 is attached.
Reference numeral 1 is opposed to the first magnet body 900 and is attached to the turbo molecular pump unit 3 side (see FIG. 2).

Further, the first and second magnet bodies 900, 9
Reference numeral 01 is composed of permanent magnets, and is provided so as to attract each other, and a plurality of them are arranged annularly around the rotation centers of the thread groove pump portion 2 and the turbo molecular pump portion 3 (see FIG. 3).

In the slip mechanism having such a structure, the turbo molecular pump portion 3 and the thread groove pump portion 2 are magnetically joined in a non-contact manner by a suction force, and an excessive load exceeding the joining force (suction force) is turbo-charged. When the molecular pump portion 3 is acted on, slippage occurs due to the load, and only the thread groove pump portion 2 is allowed to rotate.

It should be noted that the turbo molecular pump section 3 alone has good exhaust efficiency on the high vacuum side, and the thread groove pump section 2 only has good exhaust efficiency on the low vacuum side. The reason why there is a difference in the efficient pressure band is that the turbo-molecular pump unit 3 is provided with the blade portion 301 effective for exhausting gas on the high vacuum side, whereas the thread groove pump unit 2 is on the low vacuum side. This is because the screw portion 201 that is effective for exhausting gas is provided.

Next, the operation of the vacuum pump configured as described above will be described with reference to FIG.

According to this vacuum pump, the turbo molecular pump section 3 does not rotate in the high pressure region (low vacuum side) where the gas to be exhausted is at the beginning of the operation, and only the thread groove pump section 2 is rotated. Rotate.

That is, when the motor 6 is started, the rotational force of the screw pump rotor 200 tends to be transmitted to the turbo pump rotor 300 side via the magnetic coupling portion 9.

On the low vacuum side, however, an excessive load acts on the turbo molecular pump section 3, and the load exceeds the attractive force of the magnetic coupling section 9, and the slippage at the magnetic coupling section 9 becomes large.

Therefore, the rotational force of the screw pump rotor 200 is not transmitted to the turbo pump rotor 300 side, the turbo molecular pump unit 3 does not rotate, only the thread groove pump unit 2 rotates, and the gas generated by the screw unit 201 is changed. Is exhausted.

As described above, on the low vacuum side, the load applied to the turbo molecular pump unit 3 escapes through the slippage in the magnetic coupling unit 9, and the reduction of the rotation speed and the heat generation due to the load are prevented.

Further, when the pressure of the gas to be exhausted gradually decreases and reaches the high vacuum side, the load acting on the turbo molecular pump section 3 becomes less than the suction force of the magnetic coupling section 9 as a result, and the suction is performed. Turbo molecular pump part 3 by force
And the thread groove pump portion 2 are joined in a non-contact manner.

As a result, the rotational force of the screw pump rotor 200 is transmitted to the turbo pump rotor 300 side via the magnetic coupling portion 9, and as a result, in addition to the thread groove pump portion 2, the turbo molecular pump portion 3 also rotates. And its wings 30
The gas is exhausted according to 1.

That is, in the vacuum pump of this embodiment, depending on the load between the turbo molecular pump section 3 and the thread groove pump section 2, in the pressure band (low vacuum side) where an excessive load acts on the turbo molecular pump section 3. It is configured such that slippage occurs and the rotation of the turbo molecular pump unit 3 is stopped.
Therefore, the turbo molecular pump unit 3 receives an excessive load.
Can be prevented from continuing to rotate, that is, reduction in the number of revolutions and heat generation can be prevented, exhaust efficiency can be improved, and the pressure range in which exhaust can be performed can be expanded.

Further, according to this vacuum pump, the rotation stop of the turbo molecular pump unit 3 due to the load is not caused by the mechanism for separating the thread groove pump unit 2 and the turbo molecular pump unit 3 but by the slip, The device structure is also simple.

As for the sliding mechanism, the one having the structure shown in FIG. 4 or 5 can be applied.

The sliding mechanism of FIG. 4 utilizes solid friction and is composed of first and second contact portions 10 and 11.

The first contact portion 10 is located between the thread groove pump portion 2 and the turbo molecular pump portion 3 and is attached to the thread groove pump portion 2 side, while the second contact portion 11 is provided. Is slidably in contact with the first contact portion 10 and is attached to the turbo molecular pump portion 3 side.

The sliding mechanism having such a structure is provided with the contact portions 1
Due to the frictional force generated between 0 and 11, the turbo molecular pump unit 3
And the thread groove pump portion 2 are joined, and an excessive load exceeding the joining force (friction force) is applied to the turbo molecular pump portion 3
When this occurs, a slip occurs due to the load, and only the thread groove pump portion 2 can rotate.

The slip mechanism of FIG. 5 utilizes the viscosity of fluid, and the thread groove pump section 2 and the turbo molecular pump section 3 are used.
And a magnetic fluid 12 between them.

The magnetic fluid 12 is filled in an annular injection groove 13 formed on the end surface of the screw pump rotor 200, and is inserted and arranged so that the tip of the protrusion 14 is in contact with the magnetic fluid 12. The rear portion of the protrusion 14 is fixed to the turbo pump rotor 300. That is, magnetic fluid 1
2 directly contacts the thread groove pump unit 2 and the protrusion 1
It is provided so as to be in contact with the turbo molecular pump unit 3 via 4.

The magnetic fluid 12 is formed on both inner and outer side walls of the injection groove 13.
An electromagnet 15 is embedded to prevent the outflow of water.

The slip mechanism having such a structure is used for the magnetic fluid 1.
The thread groove pump portion 2 and the turbo molecular pump portion 3 are joined together via 2, that is, the protrusion 14 is restrained in the injection groove 13 by the viscosity of the magnetic fluid 12, whereby the turbo molecular pump portion 3 and the thread groove pump portion 2 When an excessive load exceeding the joining force (constraining force due to viscosity) acts on the turbo molecular pump unit 3, slipping occurs due to the load and only the thread groove pump unit 2 can rotate. To do.

In particular, in this sliding mechanism, all of the magnetic fluid 12 is attracted to the electromagnet 15 side so that the magnetic fluid 12 and the protrusion 14 do not come into contact with each other, whereby the thread groove pump portion 2 and the turbo molecular pump portion 3 are joined. Can be canceled and the joining force can be easily changed by adjusting the attraction force of the electromagnet 15.

Incidentally, the first and second magnet bodies 900, 9
Regarding 01, either one or both may be an electromagnet. When the electromagnet is used in this way, the turbo molecular pump unit 3 and the thread groove pump unit 2 are simply changed by changing the exciting current.
The magnetic joining force of can be easily changed.

The first rotary pump unit is not limited to the thread groove pump unit 2 and may be another turbo molecular pump unit that exhausts gas by rotation in a pressure band different from that of the turbo molecular pump unit 3. The second rotary pump unit is not limited to the turbo-molecular pump unit 3, and may be another screw groove pump unit that exhausts gas by rotation in a pressure band different from that of the screw groove pump unit 2. The type of both rotary pump parts does not matter. That is, the first and second rotary pump parts may be pumps that exhaust gas by rotation in different pressure zones.

FIG. 7 shows the exhaust characteristic of the apparatus of this embodiment. As shown by the solid line, the exhaust characteristic is the characteristic of the thread groove pump unit 2 alone (see the alternate long and short dash line) and the turbo molecular pump unit 3 alone. It is a combination of both the characteristics (see the chain line).

FIG. 8 is a comparison of the power consumption of the device of this embodiment and the conventional wide band type composite pump. The chain double-dashed line in the figure indicates the thread groove pump portion 2 of the device of this embodiment.
Power consumption (the chain line indicates the case where the electromagnetic force of the magnetic coupling part 9 is adjusted to control the slip), and the dotted line indicates the power consumption at the thread groove pump part in the conventional wide band type composite pump. Is. According to this, it can be seen from the comparison between the two-dot chain line and the dotted line that the power consumption of the device of this embodiment is obviously smaller on the low vacuum side. The alternate long and short dash line represents the power consumption of the turbo molecular pump unit 3 in the apparatus of this embodiment.

[0057]

According to the vacuum pump of the present invention,
As described above, in a pressure band in which an excessive load acts on either the first or second rotary pump unit, a slip corresponding to the load occurs between both rotary pump units, and the rotary pump unit on the side receiving the load is slipped. It is configured to stop rotation.
For this reason, it is possible to prevent the problem that the rotary pump portion continues to rotate while receiving an excessive load, that is, it is possible to prevent a decrease in the number of revolutions and heat generation, improve exhaust efficiency, and expand the pressure band in which exhaust operation is possible.

Moreover, in this vacuum pump, the rotation stop operation of the rotary pump portion based on the load is the first and second.
The structure of the device is simple because it does not depend on the mechanism for separating the rotary pump parts of the above, but due to the slip.

[Brief description of drawings]

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

FIG. 2 is a detailed explanatory diagram around a portion A shown in FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

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

FIG. 5 is a sectional view of another embodiment of the present invention.

FIG. 6 is a characteristic diagram of an apparatus according to an embodiment of the present invention.

FIG. 7 is a characteristic diagram of an apparatus according to an embodiment of the present invention.

FIG. 8 is a characteristic diagram of a turbo molecular pump.

FIG. 9 is a characteristic diagram of a thread groove pump or the like.

FIG. 10 is an explanatory diagram of a conventional broadband composite pump.

FIG. 11 is a characteristic diagram of a conventional broadband type composite pump.

[Explanation of symbols]

 2 Thread Groove Pump Section (First Rotation Pump Section) 3 Turbo Molecular Pump Section (Second Rotation Pump Section) 9 Magnetic Coupling Section (Sliding Mechanism) 10 First Contact Section 11 Second Contact Section 12 Magnetic fluid 200 Screw pump rotor 201 Screw portion 300 Turbo pump rotor 301 Wing portion 900 First magnet body 901 Second magnet body

Claims (8)

[Claims] 1. A first rotary pump part, which is configured to exhaust gas by rotation in a constant pressure range, and is provided with blades or screw parts for exhausting the gas, and the first rotary pump part. The first rotary pump unit and the second rotary pump have a second rotary pump unit including a blade portion or a screw portion for exhausting the gas by rotating in different pressure zones. A vacuum pump characterized in that the parts are joined via a slip mechanism in which a slip occurs due to a load acting on the pump part. 2. A second rotary pump, wherein the first rotary pump portion includes a screw pump rotor formed of a cylindrical body rotatably arranged, and a screw portion provided on an outer peripheral surface of the screw pump rotor. The vacuum pump according to claim 1, wherein the portion includes a turbo pump rotor formed of a cylindrical body rotatably arranged, and a blade portion provided on an outer peripheral surface side of the turbo pump rotor. 3. The vacuum pump according to claim 1, wherein the sliding mechanism comprises a magnetic coupling portion that magnetically joins the first rotary pump portion and the second rotary pump portion in a non-contact manner. . 4. A first magnetic body, wherein the magnetic coupling part is located between the first rotary pump part and the second rotary pump part, and is attached to the first rotary pump part side, 4. The vacuum pump according to claim 3, comprising a second magnet body facing the first magnet body and attached to the second rotary pump section side. 5. The vacuum pump according to claim 4, wherein the first and second magnet bodies are permanent magnets. 6. The vacuum pump according to claim 4, wherein one of the first and second magnet bodies comprises an electromagnet. 7. A sliding mechanism is located between the first rotary pump part and the second rotary pump part, and a first abutting part provided on the first rotary pump part side; The vacuum pump according to claim 1, wherein the vacuum pump comprises a second contact portion slidably in contact with the first contact portion and provided on the second rotary pump portion side. 8. The vacuum according to claim 1, wherein the sliding mechanism includes a magnetic fluid between the first rotary pump section and the second rotary pump section, the magnetic fluid being in contact with the both pump sections. pump.