JP2003172261A - Rotation shaft seal mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly prevent a lubricant in a gear box chamber from flowing out to an exhaust chamber with a simple structure without making a size of a volume type vacuum pump large. <P>SOLUTION: In the volume type vacuum pump, a driving part exists and a driving shaft is penetrated through the gear box chamber and the exhaust chamber. An oil molecule intrusion route from the gear box chamber to the exhaust chamber is constituted to a complex route comprising a single or a plurality of non-contact type shaft seals. An effect for pushing back the oil is obtained by flowing an inert gas to a direction contrary to the intrusion route of the oil molecule into the complex route. The flowing out of the lubricant to the exhaust chamber can be certainly prevented by disposing a contact type shaft seal in a predetermined direction even if the inert gas does not flow at the time of stopping of the volume type vacuum pump. A shaft seam mechanism is constituted by disposing an exhaust hole for forcedly suctioning the inside of the gear box, a bearing oil pouring hole and a single or a plurality of non-contact type shaft seals for controlling a flowing amount of the inert gas into the exhaust chamber and enhancing the pressure between piston rings to which the inert gas flows. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vacuum pump,
In particular, the present invention relates to a shaft seal mechanism for preventing outflow of lubricating oil from a gearbox chamber to an exhaust chamber and inflow of reactive gas or products from the exhaust chamber to the gearbox chamber in a positive displacement vacuum pump.

[0002]

2. Description of the Related Art In recent years, the concentration of impurities in a manufacturing apparatus has become a serious problem due to the diversification of semiconductor manufacturing processes. In such a semiconductor manufacturing process, it is an indispensable task to prevent contaminants such as lubricating oil used in a vacuum pump from flowing into the chamber and contaminating the semiconductor. In the processing step that requires such conditions, a positive displacement vacuum pump such as a roots type, a claw type, or a screw type is used as a general exhaust system. However, since the positive displacement vacuum pump has a drive unit, in addition to the exhaust chamber that performs the pumping action (the action of the pump to inhale, transfer, compress, and discharge gas), the lubricating oil for lubricating the drive unit is stored. Since there is a gearbox chamber, and the rotary shaft 20 penetrates both chambers, the gearbox chamber and the exhaust chamber communicate with each other through this penetrating portion, whereby the interior of the gearbox chamber The lubricating oil vapor will flow out to the exhaust chamber. The vacuum shaft seal and the shaft seal mechanism for preventing the leakage of the lubricating oil used in the rotary motion parts such as the bearings of the positive displacement vacuum pump into the exhaust chamber include a gear box chamber as shown in FIG. An intermediate chamber is provided between the exhaust chambers to prevent the oil molecules from leaking to the exhaust chamber side by filling the intermediate chamber with an inert gas, and the lubricating oil leaking to the intermediate chamber is stored in the intermediate chamber to clean the exhaust chamber side. A mechanism for keeping it at is considered. Further, there is known a shaft seal mechanism that uses a plurality of non-contact type shaft seals between the intermediate chamber and the exhaust chamber and / or between the gearbox chamber and the intermediate chamber to prevent leakage of oil molecules and lubricating oil. In addition to this, as in Japanese Patent Application Laid-Open No. 5-6070, there is a gap between the intermediate chamber and the exhaust chamber.
A shaft seal mechanism has been conventionally considered in which a throttle portion is provided and an inert gas is sealed between them at a pressure slightly higher than those in the intermediate chamber and the exhaust chamber to prevent oil molecules from leaking to the exhaust chamber side.

[0003]

However, when the shaft seal mechanism as described above is used, a space for providing the intermediate chamber is required, and the vacuum pump becomes large in size as a whole. Occurs. Even if there is an intermediate chamber, the gearbox chamber is sealed, so that oil molecules may gradually diffuse to fill the intermediate chamber and further diffuse from the intermediate chamber to the exhaust chamber. was there.

The reason for this is that when a non-contact type shaft seal such as a labyrinth seal type is generally used as a shaft seal for vacuum equipment, there is a minute gap between the seal portion and the housing due to the structure, and therefore these types are used. This is because the oil pump wraps around in a vacuum pump using. The present invention has been made in view of the above problems, and an object of the present invention is to provide a shaft seal mechanism that does not require an intermediate chamber, can manufacture a compact positive displacement vacuum pump, and can prevent the diffusion of oil molecules from the intermediate chamber. And Another object of the present invention is to provide a shaft seal mechanism that does not contaminate the exhaust chamber with oil molecules even when the flow of the inert gas is stopped when the engine is not driven.

[0005]

[Means for Solving the Problems] The above object is to provide an exhaust chamber in which a rotor is built in a housing, a gearbox chamber which is connected to an exhaust system and contains lubricating oil, the exhaust chamber and the exhaust chamber. A shaft seal mechanism for a positive displacement vacuum pump, which has a rotary shaft that penetrates a gear box chamber and drives the rotor to rotate, and a shaft seal means provided in a penetrating portion of the rotary shaft between the exhaust chamber and the gear box chamber. The problem can be solved by providing a passage for the inert gas to the gear box chamber and / or the exhaust chamber in the penetrating portion. The passage of the inert gas into the gearbox chamber in the penetrating portion is higher than that of the exhaust chamber and the gearbox chamber by inserting two piston rings at intervals and flowing the inert gas through the gas injection passage between them. Enclose with pressure. By flowing this inflowing inert gas to the gearbox side, the flow of oil molecules to the vacuum chamber side can be pushed back, and contamination of the exhaust chamber with oil molecules can be prevented. The inert gas flows into the gear box through a penetrating portion such as a bearing and is exhausted to the outside of the housing of the positive displacement vacuum pump through an exhaust hole. Further, by forcibly sucking the inert gas from the exhaust hole, the flow of the inert gas in the rotary shaft penetrating path through which the oil molecules diffuse to the exhaust chamber side becomes stronger, and the action of pushing back the oil molecules is improved. be able to. Further, in the flow path of the inert gas, a single or a plurality of non-contact type shaft seals are arranged in a complicated path so that the oil molecules do not easily flow, and the oil molecules diffused to the exhaust chamber side are made difficult to flow, The shaft seal function is further improved. An inexpensive labyrinth or the like can be used as the non-contact type shaft seal. Further, by using the contact type vacuum seal on the gear box side in a predetermined direction, even if the flow of the inert gas is stopped when the vacuum pump is not driven, there is an effect of preventing oil molecules from leaking to the vacuum chamber. The predetermined direction means that when the contact part of the seal is driven, the centrifugal force due to the rotation of the shaft works to create a gap and allows the inert gas to flow, and when the contact is stationary, the centrifugal force due to the rotation of the shaft does not occur and the seal contact part is sealed. The stopper is completely sealed and is oriented so that oil molecules do not leak to the exhaust chamber without flowing an inert gas. An inexpensive V seal or the like can be used as the contact type shaft seal. Further, a single or a plurality of non-contact type shaft seals are used in the path of the flow of the inert gas toward the exhaust chamber. By doing so, the amount of inactive gas flowing into the exhaust chamber can be suppressed.
A labyrinth may be used for the non-contact type shaft seal or seals. Further, the flow rate of the inert gas to the exhaust chamber can be further suppressed by forming the flow path to the exhaust chamber by the non-contact type seal in a complicated manner. By providing the flow of the inert gas to the exhaust chamber side, a reaction gas from the exhaust chamber flows into the shaft seal portion to generate a product in the shaft seal portion or the gear box, or a failure occurs in the exhaust chamber. There is an effect of preventing a failure caused by the product generated in step 2 entering the shaft seal part. This is because the reaction gas and products are pushed back to the exhaust chamber by creating a flow of the inert gas toward the exhaust chamber. Further, the reaction gas and products from the exhaust chamber and the lubricating oil from the gearbox chamber can be shut off by the pressure difference. Furthermore, by pouring an inert gas into the exhaust chamber, it is possible to dilute the concentration of the reaction gas, which has an effect of making it difficult for a product to form in the exhaust chamber or the exhaust port. By increasing the temperature of the inert gas flowing into the exhaust chamber side, it is possible to obtain a structure in which it is difficult to generate further products. Also,
An injection port for injecting lubricating oil is provided in a bearing for rotatably fixing the rotating shaft. With this configuration, the bearing can always be filled with the lubricating oil, and there is an effect of preventing the bearing from being destroyed or generating heat due to lack of the lubricating oil. Further, by controlling the amount of lubricating oil, it is possible to drive with lower power. When the positive displacement vacuum pump is used vertically, the lubricating oil can be efficiently supplied to the bearing by providing the lubricating oil inlet at the upper part of the bearing.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A shaft seal mechanism for a positive displacement vacuum pump according to an embodiment of the present invention will be described below with reference to FIGS.

[First Embodiment] FIG. 1 shows an embodiment of a shaft seal portion of a positive displacement vacuum pump 100 having a shaft seal mechanism according to the present invention. In FIG. 1, 101 is a gearbox chamber surrounded by a gearbox casing 103, and 102 is an exhaust chamber surrounded by an exhaust chamber casing 104. An exhaust rotor 105 for exhausting gas is housed in the exhaust chamber casing 104. Exhaust rotor 105 is rotating shaft 1
The rotary shaft 120 is fixed to 20 and is inserted into the gearbox chamber and rotatably supported by the gearbox casing 103 by bearings 112 and 113. The rotary shaft 120 is connected to the motor shaft 132 of the motor 106 to rotate the exhaust rotor 105. In the case of the positive displacement vacuum pump having a plurality of rotors as in this embodiment, a gear 131 for synchronizing the rotation of each rotor is fixed to the rotating shaft 120.

The rotating shaft is connected to a drive motor 106 for rotating the exhaust rotor 105 and a gear box chamber 101.
And the lubricating oil is required to rotate the rotating shaft 120 to lubricate the rotating shaft 120.
The inside of 1 is filled with oil molecules by this lubricating oil. Both the exhaust chamber 102 and the gearbox chamber 101 have bearings 11
Since the rotating shaft 120 rotatably fixed by 2, 113 penetrates, the gear box chamber 1
01 and the exhaust chamber 102 communicate with each other, and the oil molecules of the lubricating oil in the gearbox chamber 101 flow out to the exhaust chamber due to the diffusion of the oil molecules of the lubricating oil in the gap between the through portions. . In the shaft seal mechanism of the present invention, the piston rings 107 and 108 are arranged as a non-contact type shaft seal at intervals on the rotating shaft 120 portion near the exhaust chamber, and an inert gas is introduced from the gas inlet 116 between the two piston rings. Pour. The inert gas is the piston ring 1
08 through the gap between the exhaust chamber casing 104 and the gearbox chamber 101 side. On the exhaust chamber 102 side of the gearbox chamber 101, a plurality of non-contact type shaft seals (labyrinths) are arranged along the flow path of the inert gas.
109 and 110 are arranged. The inert gas flowing through the gap between the non-contact type shaft seals 109 and 110 is filled with lubricating oil. The bearings 112 and 113 of the rotating shaft 120.
And is exhausted from the exhaust hole 115. By disposing a filter that does not allow oil to pass through the exhaust hole 115 and exhausting gas through the filter, the inert gas can be exhausted without containing oil molecules. Further, by disposing one or more non-contact type shaft seals, diffusion of oil molecules from the gearbox chamber 101 to the exhaust chamber 102 can be suppressed. Further, by flowing the inert gas through the gap between the non-contact type shaft seals 109 and 110 which is a path through which the oil molecules diffuse, the inert gas has an effect of pushing back the diffusion of the oil molecules to the exhaust chamber 102 side. . In addition, by combining a plurality of non-contact type shaft seals (labyrinths) to complicate the path through which oil molecules flow into the exhaust chamber 102 side and make the structure difficult to flow, a synergistic effect with the effect of the flow of the inert gas is obtained. It can also be provided with a superior sealing function. Further, the effect of pushing back the oil molecules can be further improved by forcibly sucking the inert gas from the exhaust hole 115 to increase the flow rate of the inert gas. For example, in the case of a multi-stage vacuum pump, the exhaust port of the vacuum side positive displacement vacuum pump is connected to the exhaust port of the vacuum side positive displacement vacuum pump, and the atmosphere side vacuum pump is used as the vacuum side positive displacement vacuum pump. There is a method of forcibly exhausting the gearbox room. For the maximum air side vacuum pump of a single positive displacement vacuum pump or a multi-stage vacuum pump, by connecting another suction pump to the exhaust hole, the inert gas is forcibly sucked to increase the flow rate of the inert gas. It is also possible to improve the effect of pushing back the oil molecules.

Further, the contact type shaft seal 117 is fixed so as to rotate in conjunction with the rotating shaft 120 in the orientation shown in the figure. The contact portion 118 of the seal 117 contacts the end surface of the exhaust chamber casing 104 in the direction perpendicular to the axial direction of the shaft 120. With such an arrangement, the contact seal portion 118 of the contact type shaft seal 117 is brought into a non-contact state by a centrifugal force while the rotating shaft is rotating, and an inert gas is flowed,
When the rotating shaft is stopped, it is contact-sealed by the contact-type shaft seal 117, and the oil molecules that have diffused to the exhaust chamber 102 side without flowing an inert gas are contact-sealed by the contact-type shaft seal 117.
2, so that the exhaust chamber 102 is not contaminated with oil molecules. By arranging the contact-type shaft seal 117 in this way, it is not necessary to constantly flow the inert gas even during the stop, and the inert gas can be stopped during the stop.

The inert gas is prevented from flowing to the piston ring 107 side of the inert gas, that is, the exhaust chamber 102 side by using one or more non-contact type shaft seals, and the inert gas is introduced into the exhaust chamber 102. Controls the amount of gas flowing in. In the present embodiment, an example in which a single labyrinth 110 is used is shown, but a plurality of non-contact type shaft seals are combined to complicate the path through which the inert gas flows into the exhaust chamber 102 side and make it a structure that does not easily flow. This makes it possible to further control the amount of inert gas flowing into the exhaust chamber 102 side. By thus flowing the inert gas into the exhaust chamber, there is an effect of preventing the reaction gas and the product from flowing into the shaft seal mechanism from the exhaust chamber. Furthermore, there is also an effect that it is difficult to form a product in the exhaust port by injecting an inert gas into the exhaust reaction gas in the exhaust chamber to dilute it and exhaust it. By raising the temperature of the inert gas flowing into the exhaust chamber by winding a heater or the like, it is possible to further prevent the formation of products. Further, by providing the flow of the inert gas to the exhaust chamber 102 side, a reaction gas from the exhaust chamber 102 flows into the shaft seal portion, and a failure caused by accumulation of a product in the shaft seal portion or the gear box occurs. It is possible to prevent a failure caused by the product generated in the exhaust chamber entering the shaft seal portion. this is,
This is because the reaction gas and products are pushed back to the exhaust chamber by creating a flow of the inert gas toward the exhaust chamber 102. By increasing the temperature of the inert gas flowing into the exhaust chamber 102 by a method such as winding a heater, it is possible to obtain a structure in which it is more difficult to produce products.

Further, the pressure of the inert gas between the piston rings is increased by attaching a throttle portion to the exhaust chamber side and the gearbox chamber side with a non-contact type shaft seal or a plurality of non-contact type shaft seals such as a labyrinth, and oil molecules are generated due to the pressure difference. Has the effect of preventing the diffusion of gas from the gearbox chamber to the exhaust chamber, and the reaction gas from flowing into the gearbox chamber from the exhaust chamber. Further, an injection port 140 for injecting lubricating oil is provided in a bearing for rotatably fixing the rotary shaft. With this configuration, the bearings 112 and 113 can always be filled with the lubricating oil, and there is an effect that the bearings 112 and 113 are prevented from being broken or generated due to lack of the lubricating oil. Further, when the positive displacement vacuum pump is used vertically, the lubricating oil can be efficiently supplied to the bearing by providing the lubricating oil inlet at the upper part of the bearing.

[0012]

As described above, according to the present invention, a shaft sealing mechanism for a positive displacement vacuum pump having the following excellent effects can be constructed. First, by creating a flow of inert gas to the gearbox side, in combination with one or more non-contact type shaft seals, the oil molecules in the gearbox chamber push back the oil molecules that flow into the exhaust chamber side, and the oil molecules in the exhaust chamber It is a shaft seal performance mechanism that can prevent contamination due to. Further, by exhausting the inside of the gearbox from the exhaust hole, the flow rate of the inert gas is increased and the sealing performance can be further improved. Further, by disposing the contact type shaft seal with a predetermined fixing means, it is possible to configure an excellent vacuum pump that does not contaminate the exhaust chamber even if the flow of the inert gas is stopped when the positive displacement vacuum pump is stopped. I can. Furthermore, a path for the inert gas to flow is provided on the exhaust chamber side, and in combination with one or more non-contact type shaft seals, the inflow amount of the inert gas into the exhaust chamber is adjusted, causing a failure from the exhaust chamber. It has the effect of pushing back the intrusion of the reaction gas and products into the shaft seal mechanism. Also, by providing an injection port for injecting oil into the bearing part, it is possible to prevent the bearing from breaking and generating heat, and to control the amount of lubricating oil.
Further, it can be driven with low power.

[Brief description of drawings]

FIG. 1 is a sectional view of a shaft seal mechanism according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional shaft seal mechanism.

Continued front page    F-term (reference) 3H003 AA05 AB07 AC01 BC01 BD02                       CA01                 3H029 AA01 AA17 AB06 BB16 BB33                       BB42 CC19 CC20                 3H076 AA16 AA21 BB10 CC07 CC36                       CC61                 3J042 AA04 AA12 BA03 CA10                 3J043 AA17 HA04

Claims (10)

[Claims] 1. An exhaust chamber in which a rotor is built in a housing, a gearbox chamber communicating with an exhaust system and containing lubricating oil, and the exhaust chamber and the gearbox chamber are passed through to rotate the rotor. In a shaft seal mechanism of a positive displacement vacuum pump provided in a penetrating portion of the rotary shaft between the rotating shaft to be driven and the exhaust chamber and the gearbox chamber, an inert gas flows into the gearbox chamber at the penetrating portion. A shaft seal mechanism for a positive-displacement vacuum pump, which is provided with a passage. 2. A shaft seal mechanism for a positive displacement vacuum pump according to claim 1, wherein an exhaust hole for passing the inert gas is provided in the gear box chamber. 3. The shaft of a positive displacement vacuum pump according to claim 1, wherein one or more non-contact type shaft seals are used in a flow path of the inert gas toward the gear box chamber side. Seal mechanism. 4. The shaft seal mechanism for a positive displacement vacuum pump according to claim 3, wherein a labyrinth is used for the one or more non-contact shaft seals. 5. The positive displacement mold according to claim 1, wherein a single or a plurality of contact type shaft seals are used in a predetermined direction on the downstream side of the flow of the inert gas to the gear box chamber side. Vacuum pump shaft seal mechanism. 6. The shaft seal mechanism for a positive displacement vacuum pump according to claim 5, wherein a V seal is used as the contact shaft seal. 7. A shaft seal for a positive displacement vacuum pump according to claim 1, wherein one or a plurality of non-contact shaft seals are used in a flow path of the inert gas toward the exhaust chamber. mechanism. 8. A shaft seal mechanism for a positive displacement vacuum pump according to claim 7, wherein a labyrinth is used for the one or more non-contact shaft seals. 9. A shaft seal mechanism for a positive displacement vacuum pump according to claim 1, wherein the flow of the inert gas is also provided on the exhaust chamber side. 10. A shaft seal mechanism for a positive displacement vacuum pump according to claim 1, wherein a bearing for fixing the rotary shaft rotatably is provided with an injection port for injecting lubricating oil.