JPH0538389U - Vacuum pump - Google Patents

Abstract

(57) [Summary] [Objective] The present invention aims to improve the pump performance by increasing the flow rate of molecules such as gas and moisture without increasing the size of the pump. [Construction] The vacuum pump of the present invention is provided with a gas transfer means composed of blades 5, 6 and a screw groove 30 between the casing 1 and the rotor 4, and the cylinder 4a of the rotor 4 and the inner cylinder 7 are provided.
The screw groove portion 31 is also provided between the opening 4 and the upstream end portion of the tubular portion 4a so that the outside and the inside of the tubular portion 4a communicate with each other.
b is provided. According to the vacuum pump of the present invention, thread grooves are provided on both the outside and the inside of the cylindrical portion 4a, and the molecules are compressed by the rotation of both thread grooves, so that the flow rate of the molecules can be increased. Therefore, the pump performance can be improved by increasing the flow rate of molecules such as gas and moisture without increasing the size of the pump.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vacuum pump that evacuates a vacuum chamber or the like.

[0002]

[Prior Art]

 Conventionally, for example, when manufacturing an IC product or the like, each process is performed in each work chamber, and when one process is completed in one work chamber, the work piece is transferred to the next work chamber. Here, for example, in one working room, it may be necessary to evacuate this room (vacuum chamber), and in this case, a vacuum pump was used.

As such a vacuum pump, for example, there is a composite turbo molecular pump as shown in FIG. In the figure, reference numeral 101 is a casing, and a casing 101 is provided with a suction port 102 and a discharge port 103. A rotor 104 is housed in the casing 101, and a rotor blade 105 extending toward an inner peripheral wall surface of the casing 101 and a screw groove portion 108 having a spiral screw groove are formed in the rotor 104. The stator blades 106 and the stator 109 are attached to the inner peripheral wall surface of the casing 101 so as to face the rotor blades 105 and the thread groove portions 108. The rotor 104 is rotated by a motor 107 housed in the casing 101, and the rotor blades 105 and the thread groove portions 108 rotate at a high speed relative to the stator blades 106 and the stator 109.

A rotor shaft 112 is fixed to the rotor 104, and the rotor shaft 112 is magnetically levitated by an axial electromagnet 113 and a radial electromagnet 114 and is rotatably supported. Further, when the rotor shaft 112 which is magnetically levitated does not normally rotate and is supported by the electromagnets 113 and 114 and falls, protective bearings 115 and 116 that rotatably support and protect the rotor shaft 112 are provided on the fixed member side. The protective bearings 115 and 116 are provided so as not to come into contact with the rotor shaft 112 when the rotor shaft 112 normally rotates.

[0005]

[Problems to be solved by the device]

 In such a conventional turbo molecular pump, since the screw groove portion 108 rotates at a relatively high speed with respect to the stator 109 so that the exhaust gas can be compressed and discharged, the turbo molecular pump can be used as an all-blade turbo molecular pump. Compared with this, the pump performance can be improved by increasing the flow rate of exhaust gas. Therefore, the longer the thread groove portion 108 and the stator 109 are, the larger the flow rate of the exhaust gas can be made. However, if the thread groove portion 108 and the stator 109 are made too long, the rotor 104 is also lengthened, and the vacuum pump becomes large in size and heavy in weight. There is also a problem that the electromagnets 113 and 114 also become large in size and cause an increase in cost. Further, when the exhaust gas that has passed through the blade portions 105 and 106 passes through the thread groove portion 108, since the opening area through which the gas can pass is usually smaller than that of the blade portions 105 and 106, it passes efficiently and smoothly. There is also the problem that it becomes difficult. Then, this invention makes it a subject to solve such a problem.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides a substantially cylindrical casing, a substantially cylindrical inner cylinder arranged on the axis of the casing, and a rotor shaft rotatably driven on the axis of the inner cylinder. A rotor that is supported and has a substantially cylindrical tube portion between the casing and the inner cylinder; and a gas transfer unit that is provided between the casing and the rotor and that is configured by blades, screw grooves, and the like. In the composite vacuum pump including: a screw groove portion is provided between the inner cylinder and the cylindrical portion of the rotor, and an opening for communicating the outside and the inside of the cylindrical portion is provided at the upstream end of the cylindrical portion. It has a different structure.

[0007]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a turbo molecular pump according to an embodiment of a vacuum pump according to the present invention. First, the configuration will be described. In the figure, reference numeral 1 is a casing of a turbo molecular pump, and the entire casing 1 has a substantially cylindrical shape. Above the casing 1, an opening (not shown) of a working chamber as a vacuum chamber is provided. A suction port 2 is formed to be connected to the discharge port 3, and a discharge port 3 is formed in the lower base 13 of the casing 1. A rotor 4 is housed in the casing 1 in the axial direction, and a plurality of rotor blades 5 extending toward the inner wall surface of the casing 1 are formed radially outside the rotor 4, and the rotor blades 5 are formed. Multiple 5 are formed in multiple stages in the axial direction of the rotor 4. On the inner peripheral wall surface of the casing 1, a plurality of stator blades 6 formed in the same manner as the rotor blades 5 extend inwardly of the radius of the rotor 4 and are arranged so as to alternately overlap the rotor blades 5. .. A substantially cylindrical inner cylinder 7 is provided inside the rotor 4 and the rotor 4 has a cylindrical cylinder portion 4 a between the inner cylinder 7 and the casing 1. A thread groove portion 30 is formed on the outer side of the cylindrical portion 4a, and a thread groove portion 31 is formed on the inner side thereof, and a stator 33 is provided on the casing 1 facing the thread groove portion 30. Further, at the upper end portion (upstream end portion on the rotor blade 5 side) of the tubular portion 4a of the rotor 4, openings 4b communicating the outside and the inside of the tubular portion 4a are circumferentially spaced. And a plurality of them are formed.

On the other hand, a rotor shaft 8 is arranged on the axial portion of the inner cylinder 7 so as to rotate integrally with the rotor 4. Inside the inner cylinder 7, the rotor shaft 8 is rotationally driven at a high speed of about 20,000 to 90,000 rpm, so that the rotor blades 5 and the thread groove portions 30 and 31 are opposed to the stator blades 6, the stator 33, and the inner cylinder 7. A motor 9 for rotation, a radial electromagnet 10 for magnetically levitating the rotor shaft 8 in the radial direction for rotationally supporting the rotor shaft 8 in a non-contact manner, and a rotor shaft 8 for magnetically levitating in the axial direction via an armature disk 12 and rotating without contact. An axial electromagnet 11 for supporting is provided. Further, the upper and lower end portions of the inner cylinder 7 are prevented from directly touching the inner cylinder 7 and the like when the rotor shaft 8 rotating at high speed is not normally supported by the electromagnets 10 and 11 and is tilted. Thus, first and second protective bearings 21 and 22 that rotatably support and protect the rotor shaft 8 are provided.

Next, the operation will be described. When it is desired to empty the working chamber (vacuum chamber) by the turbo molecular pump, first, the motor 9 is started to rotationally drive the rotor 4, and the rotor blade 5 and the stator blades 6 in which the screw groove portions 30 and 31 are stationary, The stator 33 and the inner cylinder 7 are rotated at a relatively high speed with respect to the outer peripheral surfaces thereof. Thus, when the rotor blades 5 and the thread groove portions 30 and 31 rotate relative to the outer peripheral surfaces of the stator blades 6, the stator 33, and the inner cylinder 7, molecules such as gas and water in the working chamber are sucked into the suction port portion 2. When they jump into, the molecules pass through the rotor and stator blade groups 5 and 6, and then the molecules such as gas and water pass between the screw groove portion 30 and the stator 33, and at the same time, some of the molecules pass through the opening 4b. Flows into the inside of the cylindrical portion 4a and passes between the thread groove portion 31 and the outer peripheral surface of the inner cylinder 7. Then, the molecules are further discharged from the discharge port portion 3 through the discharge passage 27. At this time, molecules such as gas and water are compressed not only by the rotation of the screw groove portion 30 but also by the rotation of the screw groove portion 31, so that the flow rate becomes large. For this reason, the flow rate of molecules such as gas and water can be increased without increasing the size of the pump, and the pump performance can be improved. Further, since the opening area through which the gas can pass is increased as compared with the conventional thread groove portion, the gas can be efficiently discharged.

FIG. 2 is a view showing another embodiment of the vacuum pump according to the present invention. In the above-described embodiment, the thread groove portions 30 and 31 are provided on the outer side and the inner side of the cylindrical portion 4a of the rotor 4, whereas in this embodiment, the cylindrical portion 4a of the rotor 4 is a simple inner cylinder. They are different in that they are formed on a member, and a thread groove 40 is provided inside the casing 1 and a thread groove 41 is provided outside the inner cylinder 7. In such an embodiment, after molecules such as gas and water are conveyed by the rotor blades 5 and the stator blades 6, they are conveyed between the groove portion 40 and the cylindrical portion 4a of the rotor 4, and at the same time, Some of the molecules flow into the inside of the cylinder 4 from the opening 4b and are conveyed between the thread groove 41 and the cylinder 4a, and finally the molecules are discharged from the discharge port 3 through the exhaust passage 27. . Even in such an embodiment, it is possible to increase the flow rate of molecules such as gas and water without increasing the size of the pump, improve the pump performance, and perform efficient gas discharge.

In the above embodiment, the case where the screw groove portion is provided both on the outer side and the inner side of the cylindrical portion 4a of the rotor 4 and the case where both are not provided have been described, but the screw groove portion is provided on one side and not provided on the other side. You may make it a combination like this.

[0012]

[Effect of the device]

 As described above, according to the vacuum pump of the present invention, it is possible to increase the flow rate of molecules such as gas and water without increasing the size of the pump and improve the pump performance.

[Brief description of drawings]

1 is an overall sectional view showing an embodiment of a vacuum pump according to the present invention.

FIG. 2 is an overall sectional view showing another embodiment of the vacuum pump according to the present invention.

FIG. 3 is an overall sectional view showing a conventional vacuum pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 4 Rotor 4a Cylindrical part 5 Rotor blade (gas transfer means) 6 Stator blade (gas transfer means) 7 Inner cylinder 8 Rotor shaft 30, 31, 40, 41 Screw groove part (gas transfer means) 33 Stator (gas transfer means)

Claims (1)

[Scope of utility model registration request] 1. A substantially cylindrical casing, a substantially cylindrical inner cylinder arranged on an axial portion of the casing, and a rotor shaft rotatably supported on the axial portion of the inner cylinder so that the casing and the inner casing In a composite type vacuum pump comprising a rotor having a substantially cylindrical tubular portion between a cylinder and a gas transfer means provided between the casing and the rotor and configured by a blade portion, a screw groove portion, and the like, A vacuum pump characterized in that a thread groove portion is provided between the inner cylinder and the cylindrical portion of the rotor, and an opening for communicating the outside and the inside of the cylindrical portion is provided at the upstream end of the cylindrical portion.