VACUUM PUMP AND MEMBER USED FOR VACUUM PUMP
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.
Latest EDWARDS JAPAN LIMITED Patents:
1. Field of the Invention
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.
2. Description of the Related Art
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.
The rotating body 30 is contactless supported and position controlled by magnetic levitation implemented by radial bearings 34, 36 and a thrust bearing 38. The rotating body 30 is rotatably driven at a high speed by a drive motor 60. When the rotating body 30 rotates at a high speed, the rotary blades 32 provided at the rotating body 30 simultaneously rotate at a high speed such that these rotary blades 32 interact with the alternately disposed stator blades 40, whereby evacuation is performed.
Turbomolecular pumps generally have a back pressure dependence, that is, the pump performance is affected by the pressure on the back pressure side (outlet port side). Accordingly, in a multiple-stage blade pump, a low pressure is maintained on the inlet port side and the back pressure is increased, thereby improving the pump performance, by enlarging the diameter of the spiral groove portion 80 and increasing the axial length of the spiral groove portion 80.
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.
Japanese Patent Application Publication No. 2008-163857 discloses a technique for preventing the reduction of the opening area of outlet port inside the pump and the degradation of exhaust performance caused by the extension of the spiral groove portion. 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.
Accordingly, with the aforementioned technique, a U-shaped groove for which the radial direction from the inner side serves as a depth direction is provided with respect to a cylindrical hole connecting the spiral groove portion with the outlet port provided in the base or thread groove spacer. The reduction in the opening area of outlet port is thereby prevented. As a result, the exhaust performance of the pump is improved.
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 addition, where the spiral rotor is broken during rotation, the broken pieces thereof collide with the spiral stator and a force acts on the spiral stator or on the housing via the spiral stator. 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.
Further, in a dry etching apparatus, which is one of semiconductor fabrication apparatuses, where the pressure of process gas that has taken part in a reaction inside the chamber increases, the increase in temperature over the normal temperature results in a phase transition from a gaseous state to a solid state. For this property, when a multiple-stage blade pump is used for evacuating a dry etching apparatus, the solidified reaction products of the process gas are deposited on the spiral groove portion where The gas pressure rises, thereby degrading the exhaust performance of the pump. For this reason, the reaction products that have deposited on the interior portions of the pump should be removed periodically. However, a cleaning agent or a removal tool is difficult to insert into the U-shaped groove and therefore the removal operation becomes difficult.
Furthermore, when the reaction products are removed, it is necessary to confirm visually that all of the reaction products have been removed. Since the process as in the dry etching apparatus is typically highly corrosive, it is also necessary to verify visually after the removal whether corrosion is present on the gas flow channel surface of the housing or spiral stator and whether the surface film such as a plated film provided for corrosion protection has peeled off from the surface, and where such defects are present, they should be repaired. Where portions of the gas flow channel surface cannot be visually inspected, the residues of corrosion products or corrosion can remain unnoticed on such portions and the vacuum pump is restarted in the unrepaired state. 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. With the U-shaped groove, such as that of the conventional technique, the portion that cannot be visually inspected can be reduced in size by decreasing the groove depth. 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. A turbomolecular pump has a connector serving to connect the pump to a controller for power supply to the motor or magnetic bearings or input/output of signals. The pump structure is such that the hole for passing the connector wiring is completely isolated from the exhaust flow channel. 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. Accordingly, the problem. associated with the connector is similar to that relating to the outlet port. Namely, the increase in the spiral groove portion length requires the vacuum pump height to be increased.
Such a problem relating to the connector is not taken into account in the above-described conventional technique.
SUMMARY OF THE INVENTIONIt is the first object of the present invention to provide a vacuum pump in which the decrease in exhaust performance occurring when the spiral groove portion is extended or positioned further below inside the pump with the object of reducing the size of the vacuum pump can be prevented.
It is the second object of the present invention to provide a vacuum pump in which the operability of connector wiring that decreases when the spiral groove portion is extended or positioned further below inside the pump with the object of reducing the size of the vacuum pump can be improved.
The invention described in claim 1 provides a vacuum pump which includes an inlet port, a motor, a rotating body rotatably driven by the motor, a stator located facing the rotating body, and an outlet port for exhausting a gas that has been sucked in through the inlet port, and a gas exhaust passage combining a downstream space of the rotating body with the outlet port is formed in a flow channel of the gas, and the rotating body extends into en inner circumferential side in a radial direction of the rotating body, of the gas exhaust passage, wherein no blind portion exists at an opening edge portion of the gas exhaust passage, of the downstream space side when a gas exhaust passage forming member that forms the gas exhaust passage is viewed from at least either of an upper side or an oblique upper side, or from at least either of a lower side or an oblique lower side.
The invention described in claim 2 provides the vacuum pump according to claim 1, wherein the gas exhaust passage forming member is the stator.
The invention described in claim 3 provides the vacuum pump according to claim 1, further including a casing that covers an outer circumferential side of the rotating body and/or the stator, wherein the gas exhaust passage forming member is the casing.
The invention described in claim 4 provides the vacuum pump according no claim 1, further including a housing or a base member that supports the stator, wherein the gas exhaust passage forming member is the housing or the base member.
The invention described in claim 5 provides the vacuum pump according to claim 1, further including an outlet port member that forms the outlet port and extends inward the vacuum pump, wherein the gas exhaust passage forming member is the outlet port member.
The invention described in claim 6 provides the vacuum. pump according to any one of claims 1 to 5, wherein an inner corner portion of the opening edge portion has a rounded inner corner shape that reduces stress concentration.
The invention described in claim 7 provides a vacuum pump which includes an inlet port, a motor, a rotating body rotatably driven by the motor, a stator located facing the rotating body, and an outlet port for exhausting a gas that has been sucked in through the inlet port, and a gas exhaust passage combining a downstream space of the rotation body with the outlet port is formed in a flow channel of the gas, and the rotating body extends into an inner circumferential side in a radial direction of the rotating body, of the gas exhaust passage, wherein an inner corner portion of an opening edge portion of the gas exhaust passage, of the downstream space side has a rounded inner corner shape that reduces stress concentration.
The effect of reducing stress concentration can be obtained even when the rounding size of the rounded inner corner portion is 0.1 mm. Even greater effect can be obtained when the rounding size is further increased.
The invention described in claim 8 provides the vacuum pump according to any one of claims 1 to 7, further including a connector for connecting a controller that controls the rotation of the rotating body, wherein the housing or the base member has a nearly coaxial hole that is nearly coaxial with a rotation center axis of the rotating body, a conductor wire insertion hole into which a conductor wire that connects the connector and the motor is inserted, and a groove that combines the nearly coaxial hole with the conductor wire insertion hole.
The controller may be directly connected to the connector or may be connected by a cable.
The invention described in claim 9 provides a vacuum pump which includes an inlet port, a motor, a rotating body rotatably driven by the motor, a stator located facing the rotating body, a housing or a base member supporting the stator, and a connector for connecting a controller that controls the rotation of the rotating body, wherein the housing or the base member has a nearly coaxial hole that is nearly coaxial with a rotation center axis of the rotating body, a conductor wire insertion hole into which a conductor wire that connects the connector and the motor is inserted, and a groove that combines the nearly coaxial hole with the conductor wire insertion hole.
The invention described in claim 10 provides the vacuum pump according to claim 8 or 9, wherein an edge of at least one from the nearly coaxial hole, the conductor wire insertion hole, and the groove has a rounded outer corner shape such that damage of the conductor wire caused by contact with the edge is reduced.
The invention described in claim 11 provides the vacuum pump according to any one of claims 8 to 10, wherein an outer circumferential end of the groove in the radial direction of the rotating body is positioned further toward the outer circumferential side than an inner circumferential end of the conductor wire insertion hole.
The invention described in claim 12 provides a member for use in a vacuum pump which includes an inlet port, a motor, a rotating body rotatably driven by the motor, a stator located facing the rotating body, and an outlet port for exhausting a gas that has been sucked in through the inlet port, and a gas exhaust passage combining a downstream space of the rotating body with the outlet port is formed in a flow channel of the gas, wherein no blind portion exists at an opening edge portion of the gas exhaust passage, of the downstream space side when the member is viewed from at least either of an upper side or an oblique upper side, or from at least either of a lower side or an oblique lower side.
Examples of the aforementioned member include the stator, casing, housing, base member, and outlet port member extending inward of the vacuum pump, which constitute the vacuum pump.
In accordance with the present invention, the decrease in exhaust performance of the vacuum pump occurring when the spiral groove portion of the pump is extended or positioned further below inside the pump can be prevented.
Further, in accordance with the present invention, the degradation of wiring operability that decreases when the spiral groove portion is extended or positioned further below inside the pump can be reduced.
The preferred embodiment of the vacuum pump in accordance with the present invention will be explained below in greater detail with reference to
The first embodiment relates to a technique for improving the exhaust performance of a vacuum pump that has decreased because a rotary blade cylindrical portion 50 serving as a rotating body or a thread groove spacer 45 covers the opening of a cylindrical hole 45a or 70a serving as a gas exhaust passage combining an outlet port 90 with a downstream space S of the rotary blade cylindrical portion 50 on the space S side.
In this embodiment, a thread groove spacer 45 serving as a gas exhaust passage forming member in the configuration shown in
The opening edge portion 130 of the cylindrical hole 70a on the space S side in the base 70 is formed such that no blind portion exists at the opening edge portion 130 when the base 70 is viewed from at least either of the upper side or the oblique upper side.
Meanwhile, in the cylindrical hole 70a formed by the base 70, the opening edge portion. 130 is formed such that no blind portion exists at the opening edge portion 130 when she base 70 is viewed from at least either of the upper side or the oblique upper side. When the base 70 is viewed from at least either of the upper side or the oblique upper side, the field of view such as the cross-hatched portion in
The definition of the “upper side”, “oblique upper side”, “lower side”, and “oblique lower side” will be explained below.
The outer side of the outlet port 90 is connected by a pipe to an auxiliary pump having the usual suction power.
In the above-described related art, a U-shaped groove is formed in the opening edge portion 130 of the cylindrical hole combining the outlet port 90 with the downstream space S of the rotary blade cylindrical portion 50, the groove being formed on the space S side of the cylindrical hole.
Cylindrical shapes and cavities thereof are usually machined by turning, and when a groove is bored in the direction perpendicular to the center axial line of the cylinder in the inner wall of the cavity portion, the cutting cannot be performed to the necessary depth or the cutting process becomes complex and the production cost rises due to the restrictions such as a machinable range of the cutting tool (bite). However, with the shape of the opening edge portion 130 of the present embodiment, cutting may be performed so as to bore a hole that becomes coaxial with the cylindrical outer circumferential surface in the center axial line direction of the cylinder and therefore the machining in the turning process is facilitated.
Furthermore, when the thread groove spacer 45 or base 70 is cast, since no concave groove exists on the inner wall of the hollow portion, the mold structure does not become complex and the cast article can be easily removed from the mold, thereby making it possible to reduce the casting cost.
Further, with the present embodiment, the operation of removing the deposited reaction products, verifying the presence of corrosion on the thread groove spacer 45 or base 70, and repairing the corrosion are not complex. Therefore, the residual amount of reaction products and leak caused by poor repair of corrosion can be reduced.
Further, since the cross-hatched portions shown in
As a variation example of the first embodiment, a structure is considered in which the inner corner portion of the opening edge portion 130 of the cylindrical hole 45a on the space S side is rounded as shown in
The inner corner portions of the conventional U-shaped groove may be also rounded as shown in
The second embodiment in which the problems associated with the connector are resolved will be explained below.
In the present embodiment, as shown in
Further, as shown in
Further, the end o of she groove 102 on the outer circumferential side of the pump is located on the outside of the end i of the connector wiring hole 120 on the inner circumferential side of the pump. This is done so because by increasing the distance “L” between the two ends “o” and “i”, it is possible to ensure a larger pass-through area from the groove 102 to the connector 100.
According to this embodiment, where the depth of the groove 102 is reduced within a range in which the minimum pass-through area necessary for the wiring of the conductor wire can be ensured, the rotary blade cylindrical portion 50 or the space S for the gas flow channel located therebelow can be disposed at a lower level. Since the wiring of the conductor wire to the connector 100 is also performed by the groove of the shape obtained by cutting the wall below the inner circumferential portion of the connector wiring hole 120, the wiring connection is facilitated. Consequently, the production time of the pump can be reduced.
As a result, the rotary blade cylindrical portion 50 and the space S for the gas flow channel located therebelow can be enlarged in length to reach the lower level or disposed at the lower level without interfering with the connector wiring hole. 120. In addition, the connector 100 can be provided at a height greater than that in the conventional pump. As a result, the vacuum pump can be reduced in height.
Further, with the above-described embodiment, the machined shape of the base 70 can be simplified and the production cost thereof can be reduced, without changing significantly the structure of the conventional pump.
Claims
1. A vacuum pump comprising:
- an inlet port;
- a motor;
- a rotating body rotatably driven by the motor;
- a stator located facing the rotating body;
- an outlet port for exhausting a gas that has been sucked in through the inlet port; and
- a gas exhaust passage combining a downstream space of the rotating body with the outlet port and being formed in a flow channel of the gas,
- and the rotating body extending into an inner circumferential side in a radial direction of the rotating body, of the gas exhaust passage,
- wherein no blind portion exists at an opening edge portion of the gas exhaust passage, of the downstream space side when a as exhaust passage forming member that forms the gas exhaust passage is viewed from at least either of an upper side or an oblique upper side, or from at least either of a lower side or an oblique lower side.
2. The vacuum pump according to claim 1, wherein the gas exhaust passage forming member is the stator.
3. The vacuum pump according so claim 1, further comprising a casing that covers an outer circumferential side. of the rotating body and/or the stator, wherein
- the gas exhaust passage forming member is the casing.
4. The vacuum pump according to claim 1, further comprising a housing or a base member that supports the stator, wherein
- the gas exhaust passage forming member is the housing or the base member.
5. The vacuum pump according to claim 1, further comprising an outlet port member that forms the outlet port and extends inward the vacuum pump, wherein
- the gas exhaust passage forming member is the outlet port member.
6. The vacuum pump according to any one of claims 1 to 5, wherein an inner corner portion of the opening edge portion has a rounded inner corner shape that reduces stress concentration.
7. A vacuum pump comprising:
- an inlet port.;
- a motor;
- a rotating body rotatably driven by the motor;
- a stator located facing the rotating body; and
- an outlet port for exhausting a gas that has been sucked in through the inlet port;
- and a gas exhaust passage combining a downstream space of the rotating body with the outlet port is formed in a flow channel of the gas,
- and the rotating body extends into an inner circumferential side in a radial direction of the rotating body, of the gas exhaust passage,
- wherein an inner corner portion of an opening edge portion of the gas exhaust passage, of the downstream space side has a rounded inner corner shape that reduces stress concentration.
8. The vacuum pump according to any one of claims 1 to 7, further comprising a connector for connecting a controller that controls the rotation of the rotating body, wherein
- the housing or the base member has a nearly coaxial hole that is nearly coaxial with a rotation center axis of the rotating body, a conductor wire insertion hole into which a conductor wire that connects the connector and the motor is inserted, and a groove that combines the nearly coaxial hole with the conductor wire insertion hole.
9. A vacuum pump comprising:
- an inlet port;
- a motor;
- a rotating body rotatably driven by the motor;
- a stator located facing the rotating body;
- a housing or a base member supporting the stator; and
- a connector for connecting a controller that controls the rotation of the rotating body;
- wherein the housing or the base member has a nearly coaxial hole that is nearly coaxial with a rotation center axis of the rotating body, a conductor wire insertion hole into which a conductor wire that connects the connector and the motor is inserted, and a groove that combines the nearly coaxial hole with the conductor wire insertion hole.
10. The vacuum pump according to claim 8 or 9, wherein an edge of at least one from the nearly coaxial hole, the conductor wire insertion hole, and the groove has a rounded outer corner shape such that damage of the conductor wire caused by contact with the edge is reduced.
11. The vacuum pump according to any one of claims 8 to 10, wherein
- an outer circumferential end of the groove in the radial direction of the rotating body is positioned further toward the outer circumferential side than an inner circumferential end of the conductor wire insertion hole.
12. A member for use in a vacuum pump comprising:
- an inlet port;
- a motor;
- a rotating body rotatably driven by the motor;
- a stator located facing the rotating body; and
- an outlet port for exhausting a gas that has been sucked in through the inlet port;
- and a gas exhaust passage combining a downstream space of the rotating body with the outlet port and being formed in a flow channel of the gas,
- wherein no blind portion exists at an opening edge portion of the gas exhaust passage, of the downstream space side when the member is viewed from at least either of an upper side or an oblique upper side, or from at least either of a lower side or an oblique lower side.
Type: Application
Filed: May 31, 2010
Publication Date: Jun 7, 2012
Applicant: EDWARDS JAPAN LIMITED (Chiba, JP)
Inventors: Yoshinobu Ohtachi (Chiba), Yasushi Maejima (Chiba), Tsutomu Takaada (Chiba), Tooru Miwata (Chiba)
Application Number: 13/381,239
International Classification: F01D 1/36 (20060101);