Vacuum pump and member used for vacuum pump

Abstract

To provide a vacuum pump in which possibilities of decreased exhaust performance and gas leakage at the time of breakage of a rotor are lessened, in the case where a rotating part closes the inside opening portion of an exhaust outlet portion to decrease the height dimension of the vacuum pump, and further a connector lead wire is installed, easily.An inside opening edge portion of a gas discharge passage for combining the downstream space of the rotor with the exhaust outlet portion is caused to take a shape such that the opening edge portion has no blind portion when a gas exhaust passage forming member is viewed from at least either of an upper side or an oblique upper side, or from at least either of an lower side or an oblique lower side. Furthermore, the inner corner portion of this opening edge portion is formed into a rounded shape to reduce stress concentration. Also, a base is provided with a groove for combining a lead wire installing hole with a hole in the central part, and further the corners of these parts are formed into a rounded shape.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a vacuum pump such as a turbomolecular pump performing gas evacuation from a vacuum container such as a process chamber used in a semiconductor fabrication apparatus. More particularly, the present invention relates to a technique for improving the evacuation performance that decreases depending on the arrangement positions of an outlet port and a connector, and for reducing the size of a vacuum pump.[0003]2. Description of the Related Art[0004]A multiple-stage blade pump in which a rotary blade section and a cylindrical threaded section are combined is widely used as a large-flow-rate pump such as a turbomolecular pump.[0005]FIG. 9 illustrates an example of such a multiple-stage blade pump. This multiple-stage blade pump 200 is constituted by a tubular casing 20 having, formed in the upper portion thereof, an inlet port 10 for sucking in the gas from a chamber that is not shown in the f...

AI Technical Summary

Benefits of technology

The present invention provides a vacuum pump that can prevent a decrease in exhaust performance when the spiral groove is extended or positioned further below the pump. This is achieved by improving the connector wiring and the design of the gas exhaust passage, which reduces stress concentration and prevents damage to the conductor wire. The vacuum pump includes a housing or base member that supports the stator, an inlet port, a motor, a rotating body, a stator, and an outlet port for exhausting a gas that has been sucked in through the inlet port. The gas exhaust passage combining the downstream space of the rotating body with the outlet port is formed without any blind portion. The invention also provides a member for use in a vacuum pump that includes an inlet port, a motor, a rotating body, a stator, and an outlet port for exhausting a gas that has been sucked in through the inlet port.

Problems solved by technology

However, multiple-stage blade pumps should be designed with consideration for restrictive conditions relating to the installation thereof.

In particular, where the length of the spiral groove portion 80 is increased, the axial length of the pump itself is also increased causing problems in installation.

Thus, when the rotary section of the pump blocks a opening portion of the outlet port inside the pump, the exhaust performance is degraded because the reduction of the opening decreases the conductance and prevents the flow of gas into the outlet port.

However, where a U-shaped groove is provided from the inside with respect to the cylindrical, hole leading to the outlet port according to the technique described in Japanese Patent Application Publication No. 2008-163857, special cutting tools and settings are required during turning and the machining is difficult.

Further, even if the machining is successful, significant time and efforts are required therefor and the production cost rises.

Further, where the housing is manufactured by casting, since the concave groove exists on the inner side, the cast housing is difficult to remove from the mold, the mold structure becomes complex, and the casting cost rises significantly.

In this case, stress concentration occurs in the corners of the formed groove, thereby creating weak points in terms of the pump strength and reducing the strength of the pump itself.

However, a cleaning agent or a removal tool is difficult to insert into the U-shaped groove and therefore the removal operation becomes difficult.

Another problem is that when the corrosion advances, the strength of the spiral stator or housing decreases and the abovementioned rotor fracture occurs, the spiral stator and housing can be fractured and the gas can leak therethrough.

However, the problem arising in this case is that because the groove is shallow, a sufficient opening area cannot be ensured.

Another problem is associated with a connector.

Such a structure is used because if the exhaust flow channel and the hole are connected and gas flows to the connector, the exhaust performance is degraded or the connector is corroded.

In some cases, it can result in accidents and cause significant problems for the pump.

Further, when the height position of the lower end of the spiral groove portion is below the height position of the hole for connector wiring, the opening area of the hole for connector wiring should be reduced and the operation of passing the wiring from the motor or magnetic bearings to the connector becomes complex.

Such a problem relating to the connector is not taken into account in the above-described conventional technique.

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