JPH1193877A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oil of its chamber side from leaking to an intermediate chamber, and prevent a stain by a gas product material by arranging a spiral groove in the direction for flowing gas to an oil chamber, on a surface of a cylindrical seal part fixed to a rotary shaft in the intermediate chamber, and arranging an exhaust port in the oil chamber. SOLUTION: A spiral groove 18 is arranged in the direction for flowing gas entering all the way into an intermediate chamber 3 to an oil chamber 2 on a surface of a cylindrical seal part 5 fixed in close contact to a rotary shaft 6 in the intermediate chamber 3 having a gas introducing port. An exhaust port having a check valve is arranged in an upper part of the oil chamber 2. Inert gas is introduced to the intermediate chamber 3, and oil is pushed back to the oil chamber 2 side by using the action of compressively sending the inert gas to the oil chamber 2 side by the spiral groove 18 of a rotary shaft seal part 5. Since the inert gas compressively sent to the oil chamber 2 is exhausted outside a casing from the exhaust port, a stain of the casing can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vacuum pump,
In particular, the present invention relates to a shaft seal structure for sealing a lubricating oil or gas of a gear between an oil chamber and another chamber in a vacuum pump having a gear mechanism.

[0002]

2. Description of the Related Art As shown in FIG.
An oil chamber 2 in which a gear 8 fixed to a rotating shaft 6 and a splash plate 9 are stored, and an intermediate chamber 3 having a gas inlet 10A.
And a vacuum chamber 4 having a supply port and an exhaust port for accommodating the rotor 13 fixed to the rotating shaft 6 and connecting to a vacuum bell jar or the like.
And a pair of members such as a motor (not shown) connected to the rotating shaft 6 that penetrates these chambers and is supported by the bearing 12, and the like. Then, by rotating another rotating shaft (not shown) that is opposed via the gear 8, the rotors 13 rotate in synchronization with each other to suck and exhaust gas. The splash plate 9 serves to lubricate the gear 8 by applying oil 7 thereto.

The seal portion 5A of the rotating shaft 6 in the intermediate chamber 3
As shown in FIG. 5, a labyrinth portion 21 is provided between a housing 14A that supports the oil chamber 2 and the intermediate chamber 3 while supporting the bearing 12 and an inert gas is introduced from a gas inlet 10A of the intermediate chamber 3. . As a result, the intermediate chamber 3 is
The oil is kept at a more positive pressure, and the oil flowing from the oil chamber 2 to the intermediate chamber 3 is sealed by the centrifugal force obtained by the rotation of the rotary shaft 6.

However, due to the structure of the labyrinth part, the seal part 5
Since there is a very small gap between A and the housing 14A, there is a disadvantage that the pressure difference between the intermediate chamber 3 and the oil chamber 2 disappears, and the oil 7 in the oil chamber 2 gradually flows to the intermediate chamber 3 through the labyrinth seal portion. Was. In addition, since the inert gas to be purged has no flow, the reaction product of exhaust gas in a vacuum bell jar or the like for the purpose of removal adheres to the oil chamber or the labyrinth seal portion for a long period of use, and the lubricating oil This has caused a vacuum pump to fail.

As a device for forming a seal portion with a screw, a thread groove type rotary shaft sealing device shown in FIG.
No. 346,641. In this sealing device, the screw 34 provided on the rotating shaft 37 is threaded in a direction in which the molten metal 32 in the thread groove is pushed back into the pot wall 31 as shown by an arrow 38 by the rotation of the rotating shaft 37, As a result, the molten metal 32 is pushed back by the screw, and is prevented from leaking out of the gap between the opening 31a and the rotating shaft 37. Note that in FIG.
Is a rotary shaft, 35 is a collar, and 36 is a nut.

[0006]

The first problem is that the oil in the oil chamber passes through the shaft seal and goes to the intermediate chamber.

The reason is that the labyrinth seal system shown in FIG. 4 and the thread groove seal system shown in FIG. 6 have a small gap between the seal portion and the housing or between the screw 34 and the pot wall 31 due to the structure. This is because oil wraparound occurs in vacuum pumps using these methods.

[0008] A second problem is that the inside of the oil chamber and the shaft seal is contaminated by the products of the internal gas.

The reason is that even if the inert gas is introduced from the intermediate chamber, there is no exhaust port from the oil chamber side to the outside of the casing, and the diluting of the gas components inside the pump becomes insufficient, so that the dirt adheres. It is.

A first object of the present invention is to provide a vacuum pump in which oil in an oil chamber side does not pass through a shaft seal to an intermediate chamber. This eliminates the need for periodic replenishment of the oil in the oil chamber and the work of extracting the oil spilled to the intermediate chamber side.

A second object of the present invention is to provide a vacuum pump capable of preventing the oil chamber and the shaft seal from being contaminated by gaseous products. This extends the life of the vacuum pump and improves reliability.

[0012]

A vacuum pump according to the present invention comprises:
An oil chamber for containing oil, an intermediate chamber adjacent to the oil chamber and having a gas inlet which is separated by a casing wall, a housing, and a bearing; and a vacuum chamber adjacent to the intermediate chamber and separated by a casing wall. In a vacuum pump having a rotating shaft supported by the bearing and penetrating the oil chamber, the intermediate chamber, and the vacuum chamber, a surface of a cylindrical seal portion fixed to the rotating shaft in the intermediate chamber includes: A spiral groove is provided in a direction in which the gas introduced into the intermediate chamber flows into the oil chamber, and an exhaust port is further provided in the oil chamber.

In the present invention, as shown in FIGS. 1 to 3, a spiral groove 18 is provided in the seal portion of the rotating shaft 6, so that the inert gas introduced into the intermediate chamber 3 is supplied to the rotating shaft 6. 6 is rotated at a high speed in the rotation direction 15 of the arrow, so that the compressed air is sent to the oil chamber side and the oil 7 flowing around the shaft seal is transferred to the oil chamber 2.
Push back to the side.

Further, since the exhaust port 11 is provided in the oil chamber 2, the inert gas and the like introduced into the intermediate chamber 3 reach the oil chamber 2 through the shaft seal to dilute the exhaust gas in the casing 1. Since the exhaust gas can be exhausted, it has the effect of reducing the generation of gas products.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIGS. 1 to 3 are a sectional view of a vacuum pump and an intermediate chamber for explaining a first embodiment of the present invention, and a perspective view of a seal portion.

Referring to FIGS. 1 to 3, the vacuum pump has an oil chamber 2 for storing oil 7, a gas inlet 10 adjacent to the oil chamber 2 and separated by a wall of the casing 1, a housing 14 and a bearing 12. The intermediate chamber 3, a vacuum chamber 4 adjacent to the intermediate chamber 3 and separated by a wall of the casing 1 and having an air supply port and an exhaust port, and the oil chamber 2 supported by the bearing 12, the intermediate chamber 3, and the vacuum chamber 4 A rotating shaft 6 that penetrates and is connected to a driving unit such as a motor (not shown), and is tightly fixed to the rotating shaft 6 in the intermediate chamber 3, and the gas introduced into the intermediate chamber on the surface flows into the oil chamber 2. It mainly comprises a pair of members consisting of a cylindrical seal portion 5 provided with a spiral groove 18 in the direction.

In FIGS. 1 and 2, 8 is a gear, 9 is a splash plate for supplying oil to the gear, 13 is a rotor, and 19 is a pressure regulating valve.

Next, the operation of the vacuum pump will be described.

The inert gas such as nitrogen introduced into the intermediate chamber 3 is spirally grooved in a direction in which the oil and the inert gas flow into the oil chamber 2 when the rotating shaft 6 rotates in the direction of the arrow 15. By being sucked in the inert gas suction direction 16 and compressed and sent in the inert gas movement direction 17 by the groove 18,
Push the oil back to the oil chamber 2 side. This prevents oil from flowing into the intermediate chamber 3 through the gap between the rotary shaft seal portion 5 and the housing 4.

Next, a second embodiment will be described.
In the second embodiment, an exhaust port 11 having a check valve 20 is provided above the oil chamber 2 in the first embodiment shown in FIG. The operation will be described below.

An inert gas or the like is introduced into the intermediate chamber 3 from the inert gas inlet 10, and the inert gas or the like is compressed and sent to the oil chamber 2 by the spiral groove 18 of the rotary shaft seal 5. As a result, the oil 7 is prevented from sneaking into the intermediate chamber 3 through the seal portion 5 of the rotating shaft. In order to sufficiently obtain the effect of the compressed air supply operation of the inert gas or the like, the inert gas or the like is supplied from the inert gas inlet 10 of the intermediate chamber 3 at 0.2 kgf / cm ² or more.
The pressure is set to 1.0 kgf / cm ² by the pressure regulating valve 19 and supplied constantly.

As indicated by arrows 16 and 17, the oil chamber 2
The inert gas and the like compressed and sent to the casing 1 are exhausted from the exhaust port 11 to the outside of the casing 1 through the check valve 20. This flow of the inert gas or the like dilutes the exhaust gas for the purpose of removal in the casing 1 and reduces the contamination due to the reaction product of the gas, so that the inside of the casing 1 is higher than in the first embodiment. A cleaning effect is obtained.

[0023]

The first effect is that the oil in the oil chamber does not pass through the shaft seal to the intermediate chamber. This eliminates the need for refilling the oil chamber and extracting the oil leaking into the intermediate chamber.

The reason is that the spiral groove cut in the rotary shaft seal portion pushes back the oil flowing around, and furthermore, the inert gas and the like are compressed and sent to the oil chamber by the rotation of the spiral groove to push back the oil. Because it expands.

The second effect is that the contamination of the oil chamber and the inside of the shaft seal by gas products can be reduced to 20% or less of the conventional one.

The reason is that the introduced inert gas and the like are:
This is because the air is compressed and sent to the oil chamber by the spiral groove, dilutes the exhaust gas in the casing, prevents contamination by the product, and is exhausted from the exhaust port.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vacuum pump for describing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an intermediate chamber for describing an embodiment of the present invention.

FIG. 3 is a perspective view of a seal portion for describing the embodiment of the present invention.

FIG. 4 is a sectional view of a conventional vacuum pump.

FIG. 5 is a perspective view of a seal portion of a conventional vacuum pump.

FIG. 6 is a sectional view of a seal portion of the thread groove type rotary shaft seal sealing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Oil chamber 3 Intermediate chamber 4 Vacuum chamber 5, 5A Seal part 6 Rotating shaft 7 Oil 8 Gear 9 Splash plate 10, 10A Gas inlet 11 Exhaust port 12 Bearing 13 Rotor 14, 14A Housing 15 Rotation direction 16 Non Active gas suction direction 17 Inert gas moving direction 18 Spiral groove 19 Pressure regulating valve 20 Check valve 21 Labyrinth part

Claims (3)

[Claims] 1. A vacuum pump comprising an intermediate chamber having an oil chamber, a gas inlet, and a vacuum chamber, wherein a gas exhaust port is provided in the oil chamber. 2. An oil chamber for containing oil, an intermediate chamber adjacent to the oil chamber and having a gas inlet which is separated by a housing wall, a housing and a bearing, and adjacent to the intermediate chamber and separated by a casing wall. Vacuum pump having a vacuum chamber and a rotary shaft supported by the bearing and penetrating the oil chamber, the intermediate chamber, and the vacuum chamber, wherein the cylindrical seal portion is fixed to the rotary shaft in the intermediate chamber. A vacuum pump, wherein a spiral groove is provided on a surface of the oil pump in a direction in which gas introduced into the intermediate chamber flows into the oil chamber. 3. The vacuum pump according to claim 2, wherein a gas exhaust port is provided at an upper portion of the oil chamber.