Molecular pump

Abstract

To provide a molecular pump capable of precisely and easily calculating the temperature of a rotor with a simple configuration.SOLUTION: A molecular pump 1 includes a rotation drive mechanism 60, a rotor 50, a stator, a detection unit 70, a pressure detection part and an operation part. The detection unit 70 includes a sensor head 71 including a first principal surface 71a facing a surface of the rotor 50 and a second principal surface 71b on the opposite side of the first principal surface and provided with a first temperature sensor 74, a sensor base 72 including a third principal surface 72a facing the second principal surface 71b and provided with a second temperature sensor 75, and a connection part 73. The detection unit 70 is configured such that a configuration factor of the surface of the rotor 50 viewed from the first principal surface 71a is substantially one and that a configuration factor of the third principal surface 72a viewed from the second principal surface 71b is substantially one. The operation part calculates an estimate of the temperature of the rotor 50 on the basis of detection information of the first and second temperature sensors 74, 75 and the pressure detection part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a molecular pump, which is a type of vacuum pump.

Background Art

[0002] A molecular pump, which is a type of vacuum pump, is classified as a mechanical momentum transfer type vacuum pump in the international standard (ISO 3529-2:2020) and its corresponding Japanese industrial standard (JIS Z 8126-2:2023). Other pumps included in this classification are, for example, turbo molecular pumps and composite turbo molecular pumps. Hereinafter, these vacuum pumps are collectively referred to as molecular pumps.

[0003] A molecular pump is a mechanical momentum transfer type vacuum pump for creating a pressure state of medium vacuum or lower, and is attached to various processing devices typified by semiconductor manufacturing devices, various analyzers, electron microscopes, etc. A molecular pump mainly includes a rotor and a stator, and a rotation drive mechanism for driving the rotor to rotate at high speed.

[0004] In a molecular pump, when the rotor is driven to rotate at high speed, the gas molecules that enter from the intake port are sent toward the exhaust port side.

[0005] Here, when the molecular pump is continuously used, circumferential stress is applied to the rotor due to the above-described high-speed rotation drive, and this causes creep elongation. If the amount of creep elongation exceeds a predetermined value, there is a risk that the rotor and the stator located outside thereof will come into contact.

[0006] The amount of creep elongation of the rotor is closely related to the temperature of the rotor. If the temperature of the rotor can be constantly monitored, it becomes possible to estimate the amount of creep elongation, and thus, the maintenance timing of the molecular pump can be predicted. Therefore, a molecular pump equipped with a detection unit capable of detecting the temperature of the rotor is desired.

[0007] In this regard, if a non-contact infrared radiation thermometer is adopted as such a detection unit, precise temperature measurement becomes possible regardless of the usage conditions of the molecular pump. However, since an infrared radiation thermometer has a considerable size, it is difficult to incorporate it into the molecular pump. In addition, since an infrared radiation thermometer is also an expensive device, there is also a problem that the manufacturing cost of the molecular pump significantly increases when it is adopted. Therefore, it is not very realistic to adopt a non-contact detection unit, and it is required to adopt a detection unit with a simpler configuration.

[0008] As a document disclosing a molecular pump adopting such a detection unit, for example, there is International Publication No. 2010 / 021307 (Patent Document 1). In the molecular pump disclosed in the said publication, two parallel heat transfer paths, namely a heat transfer path via the detection unit and a heat transfer path not via the detection unit, are provided between the rotor and the stator, and a configuration in which a first temperature sensor and a second temperature sensor are arranged in each of the detection unit and the stator is adopted. Under this configuration, in the molecular pump disclosed in the said publication, the temperature of the rotor is calculated by a linear extrapolation formula of the measured values of the above two temperature sensors on the assumption that the amount of heat transfer between the rotor, the detection unit and the stator is proportional to the temperature difference.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Here, in the molecular pump disclosed in the above publication, due to the existence of heat transfer paths such as radiation and heat conduction of dilute gas, the amount of heat transfer does not necessarily proportional to the temperature difference. Therefore, it is difficult to accurately detect the temperature of the rotor by the contact type detection unit provided in the molecular pump disclosed in the above publication.

[0011] Also, in the molecular pump disclosed in the above publication, it is necessary to determine in advance the unknown constant represented by the linear extrapolation formula through measurement tests or the like. Although this unknown constant depends on the usage conditions of the molecular pump, the usage conditions of the molecular pump vary greatly from time to time. Therefore, although it is necessary to determine the unknown constant corresponding to the usage conditions each time, it is not very practical to do so, and it lacks versatility and convenience. Thus, in the conventionally known molecular pump, it has been difficult to achieve both a simple configuration and the ability to accurately and easily calculate the temperature of the rotor.

[0012] Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to provide a molecular pump capable of accurately and easily calculating the temperature of a rotor with a simple configuration.

Means for Solving the Problems

[0013] A molecular pump according to a first aspect of the present invention includes a rotational drive mechanism having an output shaft, a rotor fixed to the output shaft and rotationally driven by the rotational drive mechanism, a stator disposed opposite to the rotor along the extending direction of the output shaft, a casing that houses the rotor and to which the stator is fixed, and that is provided with an intake port and an exhaust port so as to be spaced apart from each other in the extending direction of the output shaft, a detection unit for detecting a temperature necessary for estimating the temperature of the rotor, a pressure detection unit for detecting the ambient pressure of the detection unit, and a calculation unit for calculating an estimated value of the temperature of the rotor. The detection unit includes a sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, a sensor base including a third main surface facing the second main surface, a connecting portion for connecting the sensor head and the sensor base so as to maintain a state in which the second main surface and the third main surface face each other, a first temperature sensor provided on the sensor head, and a second temperature sensor provided on the sensor base. The detection unit is configured such that a form factor of the surface of the rotor as viewed from the first main surface is substantially 1, and a form factor of the third main surface as viewed from the second main surface is substantially 1. In the molecular pump according to the first aspect of the present invention, the calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit.

[0014] The molecular pump according to the second aspect of the present invention includes a rotational drive mechanism having an output shaft, a rotor fixed to the output shaft and rotationally driven by the rotational drive mechanism, a stator disposed opposite to the rotor along the extending direction of the output shaft, a casing that houses the rotor and to which the stator is fixed, and that is provided with an intake port and an exhaust port so as to be spaced apart from each other in the extending direction of the output shaft, a detection unit for detecting a temperature necessary for estimating the temperature of the rotor, a pressure detection unit for detecting the ambient pressure of the detection unit, and a calculation unit for calculating an estimated value of the temperature of the rotor. The detection unit includes a sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, a sensor base including a third main surface facing the second main surface, a connecting portion for connecting the sensor head and the sensor base so as to hold the state in which the second main surface and the third main surface face each other, a first temperature sensor provided on the sensor head, and a second temperature sensor provided on the sensor base. The detection unit is configured such that the first main surface substantially faces only the surface of the rotor and the second main surface substantially faces only the third main surface. In the molecular pump according to the second aspect of the present invention, the calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit.

[0015] The molecular pump according to the third aspect of the present invention includes a rotary drive mechanism having an output shaft, a rotor fixed to the output shaft and rotationally driven by the rotary drive mechanism, a stator disposed opposite to the rotor along the extending direction of the output shaft, a casing that houses the rotor and to which the stator is fixed, and an intake port and an exhaust port are provided so as to be spaced apart from each other in the extending direction of the output shaft, a detection unit for detecting a temperature necessary for estimating the temperature of the rotor, a pressure detection unit for detecting the ambient pressure of the detection unit, and a calculation unit for calculating an estimated value of the temperature of the rotor. The detection unit includes a sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, a sensor base including a third main surface facing the second main surface, a connecting portion for connecting the sensor head and the sensor base so as to hold the state in which the second main surface and the third main surface face each other, a first temperature sensor provided on the sensor head, and a second temperature sensor provided on the sensor base. The detection unit is configured such that the sum of the heat transfer amount due to radiation from the rotor to the sensor head and the heat transfer amount due to gas heat conduction from the rotor to the sensor head is substantially equal to the sum of the heat transfer amount due to radiation from the sensor head to the sensor base, the heat transfer amount due to gas heat conduction from the sensor head to the sensor base, and the heat transfer amount due to solid heat conduction from the sensor head to the sensor base via the connecting portion. In the molecular pump according to the third aspect of the present invention, the calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit.

Effect of the Invention

[0016] According to the present invention, it is possible to provide a molecular pump capable of calculating the temperature of a rotor precisely and easily with a simple configuration.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments illustrate the case where the present invention is applied to a composite turbo molecular pump (a kind of molecular pump) having a turbo molecular pump section and a screw groove vacuum pump section. In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0019] (Embodiment) FIG. 1 is a schematic cross-sectional view of a molecular pump according to an embodiment. First, with reference to FIG. 1, the schematic configuration of the molecular pump 1 according to the present embodiment will be described.

[0020] As shown in FIG. 1, the molecular pump 1 includes a turbo molecular pump section 10A and a screw groove vacuum pump section 10B as a configuration for realizing an exhaust function, and has a substantially cylindrical outer shape as a whole. The molecular pump 1 includes a case 20, a base 30, a stator 40, a rotor 50, a rotational drive mechanism 60, a detection unit 70, a pressure detection unit 80, and an arithmetic unit 90 (see FIG. 3). The detection unit 70, the pressure detection unit 80, and the arithmetic unit 90 are used for estimating the temperature of the rotor 50, and the details thereof will be described in detail later.

[0021] The casing of the molecular pump 1 is composed of a case 20, a base 30, and a stator base 43 among the stator 40. The casing is provided with an intake port 21 and an exhaust port 31. The intake port 21 and the exhaust port 31 are spaced apart from each other in the extending direction of the output shaft 61 of the rotational drive mechanism 60 described later.

[0022] In the internal space of the casing, the remaining stator disk 41 and the holding member 42 of the stator 40, the rotor disk 51 and the cylindrical portion 52 that constitute the rotor 50, and the rotational drive mechanism 60 are mainly accommodated. An exhaust passage is provided inside the casing so as to connect the intake port 21 and the exhaust port 31.

[0023] The turbo molecular pump section 10A is mainly composed of the stator disk 41 of the stator 40 and the rotor disk 51 of the rotor 50. A plurality of stationary blade portions 45 are provided on the stator disk 41. A plurality of moving blade portions 55 are provided on the rotor disk 51. The plurality of stationary blade portions 45 and the plurality of moving blade portions 55 are arranged to face each other, and as the rotor disk 51 rotates at high speed, the turbo molecular pump section 10A exhibits an exhaust function.

[0024] The screw groove vacuum pump section 10B is mainly composed of the stator base 43 of the stator 40 and the cylindrical portion 52 of the rotor 50. A screw groove portion 47 is provided on the stator base 43. The cylindrical portion 52 is arranged to face the screw groove portion 47, and as the cylindrical portion 52 rotates at high speed, the screw groove vacuum pump section 10B exhibits an exhaust function.

[0025] The turbo molecular pump section 10A is arranged at a position downstream of the intake port 21 in the exhaust passage. The screw groove vacuum pump section 10B is arranged at a position downstream of the turbo molecular pump section 10A and upstream of the exhaust port 31 in the exhaust passage. Thus, in the molecular pump 1, the gas to be exhausted is exhausted in the order of the intake port 21, the turbo molecular pump section 10A, the screw groove vacuum pump section 10B, and the exhaust port 31.

[0026] The base 30 is made of a substantially disk-shaped metal member and constitutes the lower end portion of the casing. A concave portion is provided at the center of the upper surface of the base 30. The rotation drive mechanism 60 is placed in this concave portion so that a part of it is accommodated.

[0027] The rotation drive mechanism 60 has an output shaft 61 rotatably supported by bearings, a motor that rotationally drives the output shaft 61, and a housing 62 that houses a part of the output shaft 61, the bearings, and the motor. The housing 62 is of a bottomed substantially cylindrical shape. The housing 62 is arranged such that its central axis overlaps with the output shaft 61.

[0028] The upper end side portion of the output shaft 61 is drawn out from the housing 62 to the outside. A rotor 50 is fixed to the output shaft 61 at the portion drawn out to the outside of the housing 62. Thus, the rotation drive mechanism 60 can rotate the rotor 50 at high speed in the direction of arrow DR shown in the figure (hereinafter, this direction is referred to as the rotation direction DR) around the rotation axis RA shown in the figure defined by the output shaft 61.

[0029] The rotor 50 has the rotor disk 51 and the cylindrical portion 52 as described above, and is composed of a metal member in which the rotor disk 51 and the cylindrical portion 52 are integrated. In the present embodiment, a rotor 50 made of an aluminum member is used.

[0030] The rotor 50 is fixed to the output shaft 61 by inserting and fitting the output shaft 61 of the rotary drive mechanism 60 into a hole provided in the central portion of the rotor disk 51. The cylindrical portion 52 extends downward from the peripheral edge of the lower end of the rotor disk 51. The rotor disk 51 has a plurality of moving blade stages arranged such that a plurality of moving blade portions 55 are aligned along the circumferential direction, and these are arranged in multiple stages along the extending direction of the output shaft 61 of the rotary drive mechanism 60.

[0031] The rotor disk 51 has a substantially cylindrical hub portion 54 and a plurality of moving blade portions 55. The hub portion 54 is fixed to the upper end side portion of the output shaft 61 of the rotary drive mechanism 60 described above and surrounds this upper end side portion. The plurality of moving blade portions 55 project outward from the hub portion 54 along the radial direction of the rotor disk 51.

[0032] In the hub portion 54, at the central portion of the axial end face on the side facing the housing 62 of the rotary drive mechanism 60, a recess 54a (see FIG. 2 described later) recessed in a direction away from the housing 62 is provided. The upper end portion of the housing 62 is surrounded by this recess 54a.

[0033] FIG. 2 is an enlarged cross-sectional view of the vicinity of the detection unit shown in FIG. 1. FIG. 3 is a diagram showing the configuration of the functional blocks of the molecular pump shown in FIG. 1. FIG. 4 is a schematic diagram for explaining the heat transfer path from the rotor to the sensor base in the molecular pump shown in FIG. 1. Next, with reference to FIGS. 2 to 4 and the aforementioned FIG. 1, the detailed configuration of the detection unit 70 and its vicinity will be described. In FIG. 4, the shapes of the rotor 50, the sensor head 71, the sensor base 72, and the connecting portion 73 are shown in a simplified manner.

[0034] As shown in FIGS. 1 to 3, in addition to the stator disk 41 of the stator 40 and the rotor disk 51 of the rotor 50 described above, the molecular pump 1 further includes a detection unit 70, a pressure detection unit 80, and a calculation unit 90.

[0035] As shown in Fig. 2, the detection unit 70 includes a sensor head 71, a sensor base 72, a connecting portion 73, a first temperature sensor 74, and a second temperature sensor 75. The detection unit 70 is disposed between the hub portion 54 and the housing 62 so as to face a curved corner portion 54a1 that is the boundary between the bottom surface and the inner peripheral surface of the recess 54a provided in the hub portion 54. The detection unit 70 is for detecting the temperature necessary for estimating the temperature of the rotor 50.

[0036] As shown in Fig. 2, the sensor head 71 is an annular plate-shaped component curved along the curved surface of the corner portion 54a1. More specifically, the sensor head 71 extends so as to go around in the circumferential direction that coincides with the rotation direction DR of the rotor 50. The sensor head 71 includes a first main surface 71a facing the corner portion 54a1 and a second main surface 71b located on the side opposite to the first main surface 71a.

[0037] The sensor head 71 is configured such that the shortest distance from any point on the first main surface 71a to the surface of the rotor 50 (in this embodiment, the surface of the corner portion 54a1) is substantially the same over the entire first main surface 71a. Thereby, the accuracy of temperature estimation of the rotor 50 using the detection unit 70 or the like can be improved, and this point will be described in detail later.

[0038] As shown in Fig. 2, the sensor base 72 is an annular plate-shaped component attached to the upper end portion of the housing 62. More specifically, the sensor base 72 extends so as to go around in the circumferential direction that coincides with the rotation direction DR of the rotor 50. The sensor base 72 includes a third main surface 72a facing the second main surface 71b of the sensor head 71 and a fourth main surface 72b located on the side opposite to the third main surface 72a. The sensor base 72 is attached to the housing 62 with at least a part of the fourth main surface 72b in contact with the surface of the housing 62.

[0039] Both the sensor head 71 and the sensor base 72 are made of metal members. In the present embodiment, the sensor head 71 and the sensor base 72 made of aluminum members are used. Further, an anodizing treatment is applied to at least a portion of the first main surface 71a of the sensor head 71 and the surface of the rotor 50 that faces the first main surface 71a, thereby improving the emissivity. As a result, the emissivity of these portions is higher than either the emissivity of the second main surface 71b of the sensor head 71 or the emissivity of the third main surface 72a of the sensor base 72. By configuring in this way, the accuracy of temperature estimation of the rotor 50 using the detection unit 70 and the like can be improved, which will be described in detail later.

[0040] The sensor head 71 and the sensor base 72 are connected by a connecting portion 73 so that the second main surface 71b of the sensor head 71 and the third main surface 72a of the sensor base 72 face each other.

[0041] The specific configuration of the connecting portion 73 is not particularly limited, but it is preferably excellent in heat insulation performance. In the present embodiment, a heat-insulating bolt 73a and a heat-insulating washer 73b are used as the connecting portion 73.

[0042] The connecting portion 73 may be singular or plural. In the present embodiment, four connecting portions 73 are arranged at rotationally symmetric positions of 90° when viewed along the axial direction of the rotation drive mechanism 60.

[0043] At a predetermined position of the sensor head 71, a first temperature sensor 74 is provided. The first temperature sensor 74 detects the temperature of the sensor head 71 and outputs the detected information to an arithmetic unit 90 described later. At a predetermined position of the sensor base 72, a second temperature sensor 75 is provided. The second temperature sensor 75 detects the temperature of the sensor base 72 and outputs the detected information to the arithmetic unit 90. In the present embodiment, the first temperature sensor 74 and the second temperature sensor 75, which are constituted by contact type temperature sensors, are used.

[0044] A purge gas is supplied to the molecular pump 1 (see the arrow in FIG. 2). More specifically, the purge gas is supplied to the molecular pump 1 so as to flow along the output shaft 61 of the rotation drive mechanism 60, then flow through the space between the rotor 50 and the housing 62, and further flow toward the exhaust port 31 thereafter. By supplying the purge gas in this way, when the process gas inhaled from the intake port 21 is a corrosive gas, the internal components of the rotation drive mechanism 60 can be protected from the process gas. Here, the detection unit 70 is disposed on the above-described flow path of the purge gas, including the space between the rotor 50 and the housing 62. Thereby, when the process gas is a corrosive gas, the detection unit 70 can be protected from the process gas. Further, by filling the periphery of the detection unit 70 with a known gas in this way, it is possible to more easily estimate the amount of heat transfer due to gas heat conduction. The type of the purge gas is not particularly limited as long as it is an inert gas, and for example, nitrogen gas or the like is preferably used.

[0045] The pressure detection unit 80 detects the ambient pressure of the detection unit 70 and outputs this detection information to the calculation unit 90. As the pressure detection unit 80, a known pressure sensor is used. The installation position of the pressure detection unit 80 is not particularly limited as long as it is downstream of the rotor 50 when the conductance of the exhaust passage is sufficiently large. As an example, in the present embodiment, the pressure detection unit 80 is provided at a position downstream of the screw groove vacuum pump unit 10B (see FIG. 1). Note that as the pressure detection unit 80, it is also possible to use an external pressure sensor provided in the pipe located downstream of the exhaust port 31.

[0046] The calculation unit 90 is provided inside or outside the space of the casing of the molecular pump 1. The calculation unit 90 calculates an estimated value of the temperature of the rotor 50. More specifically, the calculation unit 90 calculates an estimated value of the temperature of the rotor 50 based on the detection information detected by the first temperature sensor 74, the detection information detected by the second temperature sensor 75, and the detection information detected by the pressure detection unit 80.

[0047] Here, in the molecular pump 1 according to the present embodiment, as shown in FIG. 2, the first main surface 71a of the sensor head 71 faces substantially only the surface of the rotor 50. Further, the second main surface 71b of the sensor head 71 faces substantially only the third main surface 72a of the sensor base 72.

[0048] By configuring in this way, the form factor of the surface of the rotor 50 as seen from the first main surface 71a of the sensor head 71 can be made substantially 1, and the form factor of the third main surface 72a of the sensor base 72 as seen from the second main surface 71b of the sensor head 71 can be made substantially 1. The form factor refers to the ratio of the radiant energy radiated from a certain surface that reaches another certain surface.

[0049] By configuring as described above, the molecular pump 1 can be made such that the temperature of the rotor 50 can be calculated precisely and easily with a simple configuration. Hereinafter, the details will be described with reference to FIG. 4.

[0050] As shown in FIG. 4, in the molecular pump 1 according to the present embodiment, as the form of heat transfer for the sensor head 71 to enter and exit, radiation from the rotor 50 to the sensor head 71, gas heat conduction from the rotor 50 to the sensor head 71, radiation from the sensor head 71 to the sensor base 72, gas heat conduction from the sensor head 71 to the sensor base 72, and solid heat conduction from the sensor head 71 to the sensor base 72 via the connecting portion 73 are included.

[0051] Let the heat transfer amount due to radiation from the rotor 50 to the sensor head 71 be Qe1, the heat transfer amount due to gas heat conduction from the rotor 50 to the sensor head 71 be Qg2, the heat transfer amount due to radiation from the sensor head 71 to the sensor base 72 be Qe3, the heat transfer amount due to gas heat conduction from the sensor head 71 to the sensor base 72 be Qg4, and the heat transfer amount due to solid heat conduction from the sensor head 71 to the sensor base 72 via the connecting portion 73 be Qc5. In this case, as shown in the following formula (1), the sum of the heat transfer amount Qe1 and the heat transfer amount Qg2 and the sum of the heat transfer amount Qe3, the heat transfer amount Qg4, and the heat transfer amount Qc5 are substantially equivalent. By configuring the detection unit 70 so as to have the form factor as described above, disturbances other than the above five forms of heat transfer are removed, and thus the heat input and output in the sensor head 71 are simplified into the above five forms of heat transfer.

[0052]

Number

[0053] Here, when one of the two objects faces substantially only the other, the heat transfer amount Qe due to radiation and the heat transfer amount Qg due to gas heat conduction between these two objects are generally described by the following equations (2) and (3), respectively. Note that ε1 is the emissivity of one object. ε2 is the emissivity of the other object. σ is the Stefan-Boltzmann constant. T1 is the temperature of the above-mentioned one object. T2 is the temperature of the above-mentioned other object. S1 is the surface area of the above-mentioned one object. x is the distance between the above two objects. L is the mean free path of the gas, which is a value determined by the type and pressure of the gas flowing between the two objects. R is the gas constant. p0 is the ambient pressure. d1 is a constant, and its value is 2.4. γ2 is a constant, and its value is 1.92.

[0054]

Number

[0055]

Number

[0056] Also, the heat transfer amount Qc due to solid heat conduction of the member connecting the above two objects is generally described by the following equation (4). Note that λ is the thermal conductivity of the member connecting the above two objects. A is the cross-sectional area of the member connecting the above two objects. δ is the length of the member connecting the above two objects.

[0057]

Number

[0058] From the above, the heat transfer amount Qe1 is expressed as a function of the estimated temperature Tr of the rotor 50 and the temperature Th of the sensor head 71 detected by the first temperature sensor 74. The heat transfer amount Qg2 is expressed as a function of the estimated temperature Tr of the rotor 50, the temperature Th of the sensor head 71, and the ambient pressure p0 of the detection unit 70 detected by the pressure detection unit 80. The heat transfer amounts Qe3 and Qc5 are expressed as functions of the temperature Th of the sensor head 71 and the temperature Tb of the sensor base 72. The heat transfer amount Qg4 is expressed as a function of the temperature Th of the sensor head 71, the temperature Tb of the sensor base 72, and the ambient pressure p0 of the detection unit 70.

[0059] Therefore, the arithmetic unit 90 acquires the detection information detected by each of the first temperature sensor 74, the second temperature sensor 75, and the pressure detection unit 80 as described above, and performs a predetermined calculation based on these detection information and the above formula (1), whereby the estimated temperature T of the rotor 50 r can be calculated precisely and easily. Note that the accuracy of estimating the temperature of the rotor 50 when configured as in the molecular pump 1 according to the present embodiment has been confirmed by the verification test described later.

[0060] Also, in the molecular pump 1 according to the present embodiment, as described above, the detection unit 70 is composed of the sensor head 71, the sensor base 72, the connecting portion 73, the first temperature sensor 74 and the second temperature sensor 75 which are contact type temperature sensors. By configuring in this way, compared with the case where a non-contact type temperature sensor is used as the detection unit, not only can it be made inexpensive, but also a detection unit and a molecular pump having a simple and compact configuration can be obtained.

[0061] Furthermore, in the molecular pump 1 according to the present embodiment, when the arithmetic unit 90 estimates the temperature of the rotor 50 using the formula (1), the formula (1) is composed only of constants that do not depend on the usage conditions of the molecular pump 1. Therefore, it is possible to obtain a molecular pump excellent in versatility and convenience that does not require determining unknown constants corresponding to the usage conditions of the molecular pump 1 each time when calculating the temperature of the rotor 50.

[0062] Therefore, by configuring the molecular pump 1 according to the present embodiment, it is possible to obtain a molecular pump that can calculate the temperature of the rotor precisely and easily with a simple configuration.

[0063] Also, in the molecular pump 1 according to the present embodiment, as described above, the sensor head 71 is configured such that the shortest distance from an arbitrary point on the first main surface 71a of the sensor head 71 to the surface of the rotor 50 is substantially the same over the entire first main surface 71a. By configuring in this way, x in the formula (3), which is the distance between the rotor 50 and the first main surface 71a, can be made a constant. Therefore, it becomes possible to calculate the temperature of the rotor 50 more precisely.

[0064] From the viewpoint of calculating the temperature of the rotor 50 more precisely, it is preferable that the shortest distance from an arbitrary point on the second main surface 71b of the sensor head 71 to the third main surface 72a of the sensor base 72 is also substantially the same over the entire second main surface 71b. In this regard, since x in the formula (3) (that is, the distance between the second main surface 71b and the third main surface 72a) is a relatively large value, even when the above-mentioned shortest distance is not substantially the same over the entire second main surface 71b, by performing a predetermined calculation using the average value of the distances from an arbitrary point on the second main surface 71b of the sensor head 71 to the third main surface 72a of the sensor base 72, the temperature of the rotor 50 can be calculated with sufficiently high accuracy.

[0065] Furthermore, in the molecular pump 1 according to the present embodiment, as described above, the emissivity of the first main surface 71a of the sensor head 71 and the emissivity of at least the portion of the surface of the rotor 50 facing the first main surface 71a have a higher emissivity than any of the emissivity of the second main surface 71b of the sensor head 71 and the emissivity of the third main surface 72a of the sensor base 72.

[0066] By configuring it in this way, the heat transfer by radiation from the rotor 50 to the sensor head 71 can be further promoted. As a result, since the temperature difference between the sensor head 71 and the sensor base 72 increases, it becomes possible to improve the accuracy of estimating the temperature of the rotor 50.

[0067] In addition, in the molecular pump 1 according to the above-described embodiment, the case where the sensor base 72 is made of a separate member from the housing 62 has been exemplified and described. However, at least a part of the sensor base 72 (that is, a part or the whole of the sensor base 72) may be configured as a part of the housing 62.

[0068] (Verification Test) In the verification test, the accuracy of estimating the temperature of the rotor 50 using the detection unit 70 or the like was verified by comparing the estimated value Tr of the temperature of the rotor 50 during the operation of the molecular pump 1 according to this embodiment with the actually measured value Trm of the temperature of the rotor 50 using a non-contact temperature sensor. Here, for this verification test, an infrared radiation thermometer as a non-contact temperature sensor was attached to a predetermined position of the molecular pump 1. The estimated value Tr is calculated by the arithmetic unit 90 acquiring the detection information detected by each of the first temperature sensor 74, the second temperature sensor 75, and the pressure detection unit 80 and performing a predetermined calculation based on these detection information and the above formula (1). In this verification test, a purge gas of 40 sccm was constantly flowed from the lower side of the output shaft 61 of the rotation drive mechanism 60 (refer to the arrow in FIG. 2). Further, in this verification test, while flowing a simulated process gas from the intake port 21, the temperature and pressure of the rotor 50 were changed by changing the flow rate in the order of 0 sccm, 1000 sccm, 1500 sccm, and 2000 sccm.

[0069] FIG. 5 is a graph showing the measurement results of the verification test. The horizontal axis represents the operating time (minutes) of the molecular pump 1, and the vertical axis represents the temperature (° C) and the pressure (Pa) of the rotor 50. FIG. 6 is a table showing the measurement results of the verification test. This table shows the correspondence between the actually measured value Trm of the temperature of the rotor 50 and the estimated value Tr of the temperature of the rotor 50 at a predetermined operating time of the molecular pump 1.

[0070] From the results shown in FIGS. 5 and 6, the estimated value Tr of the temperature of the rotor 50 using the detection unit 70 and the like changes without significantly differing from the actually measured value Trm of the temperature of the rotor 50 using the infrared radiation thermometer, and the difference generated between these estimated value Tr and actually measured value Trm is found to be within about 2° C. at most.

[0071] From the above results, it was found that by configuring as in the molecular pump 1 according to the present embodiment, the estimated value of the temperature of the rotor 50 can be accurately calculated.

[0072] (Supplementary Note) Summarizing the characteristic configuration of the molecular pump disclosed in the above-described embodiment, it is as follows.

[0073] [Supplementary Note 1] A rotational drive mechanism having an output shaft, A rotor that is fixed to the output shaft and is rotationally driven by the rotational drive mechanism, A stator disposed opposite to the rotor along the extending direction of the output shaft, A casing that houses the rotor and to which the stator is fixed, and an intake port and an exhaust port are provided so as to be separated from each other in the extending direction of the output shaft, A detection unit for detecting a temperature necessary for estimating the temperature of the rotor, A pressure detection unit for detecting the ambient pressure of the detection unit, And a calculation unit for calculating an estimated value of the temperature of the rotor, The detection unit is A sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, A sensor base including a third main surface facing the second main surface, A connecting portion connecting the sensor head and the sensor base to maintain a state in which the second main surface and the third main surface face each other, A first temperature sensor provided on the sensor head, A second temperature sensor provided on the sensor base, and having, The detection unit is configured such that the form factor of the surface of the rotor as viewed from the first main surface is substantially 1, and the form factor of the third main surface as viewed from the second main surface is substantially 1, The calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit, a molecular pump. [Appendix 2] A rotary drive mechanism having an output shaft, A rotor that is rotationally driven by the rotary drive mechanism by being fixed to the output shaft, A stator disposed opposite to the rotor along the extending direction of the output shaft, A casing that houses the rotor and to which the stator is fixed, and having an intake port and an exhaust port provided so as to be spaced apart from each other in the extending direction of the output shaft, A detection unit for detecting a temperature necessary for estimating the temperature of the rotor, A pressure detection unit for detecting the ambient pressure of the detection unit, A calculation unit for calculating an estimated value of the temperature of the rotor, and comprising, The detection unit is A sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, A sensor base including a third main surface facing the second main surface, A connecting portion that connects the sensor head and the sensor base in order to hold the second main surface and the third main surface in a facing state; A first temperature sensor provided on the sensor head; A second temperature sensor provided on the sensor base, and having; The detection unit is configured such that the first main surface faces substantially only the surface of the rotor, and the second main surface faces substantially only the third main surface; The calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit. A molecular pump. [Appendix 3] A rotary drive mechanism having an output shaft; A rotor that is rotationally driven by the rotary drive mechanism by being fixed to the output shaft; A stator disposed opposite to the rotor along the extending direction of the output shaft; A casing that houses the rotor and to which the stator is fixed, and that is provided with an intake port and an exhaust port so as to be spaced apart from each other in the extending direction of the output shaft; A detection unit for detecting the temperature necessary for estimating the temperature of the rotor; A pressure detection unit for detecting the ambient pressure of the detection unit; And a calculation unit that calculates an estimated value of the temperature of the rotor, The detection unit includes: A sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface; A sensor base including a third main surface facing the second main surface; A connecting portion that connects the sensor head and the sensor base in order to hold the second main surface and the third main surface in a facing state; A first temperature sensor provided on the sensor head; A second temperature sensor provided on the sensor base, and having; The detection unit is configured such that the sum of the heat transfer amount due to radiation from the rotor to the sensor head and the heat transfer amount due to gas heat conduction from the rotor to the sensor head is substantially equal to the sum of the heat transfer amount due to radiation from the sensor head to the sensor base, the heat transfer amount due to gas heat conduction from the sensor head to the sensor base, and the heat transfer amount due to solid heat conduction from the sensor head to the sensor base via the connecting portion. The calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit, in a molecular pump. [Appendix 4] The rotation drive mechanism further has a housing that houses at least a part of the output shaft. The molecular pump according to any one of Appendices 1 to 3, wherein the sensor base further includes a fourth main surface that is located on the side opposite to the third main surface and contacts the housing. [Appendix 5] The rotation drive mechanism further has a housing that houses at least a part of the output shaft. The molecular pump according to any one of Appendices 1 to 3, wherein at least a part of the sensor base is constituted by a part of the housing. [Appendix 6] The housing is a bottomed substantially cylindrical shape arranged such that the central axis of the housing overlaps with the output shaft. One end of the output shaft is arranged outside the housing. The rotor is fixed to the one end of the output shaft and has a hub portion that surrounds the one end of the output shaft. A concave portion recessed in a direction away from the housing is provided at the central portion of the axial end face on the side of the hub portion facing the housing. The end portion of the housing on the one end side of the output shaft is surrounded by the concave portion. The molecular pump according to appended claim 4 or 5, wherein the detection unit is disposed between the hub portion and the housing so as to face a corner portion that is a boundary portion between the bottom surface and the inner peripheral surface of the concave portion. [Appended Note 7] The molecular pump according to any one of appended claims 4 to 6, wherein the detection unit is disposed on a flow path of a purge gas flowing through a space between the rotor and the housing. [Appended Note 8] The molecular pump according to any one of appended claims 1 to 7, wherein the emissivity of the first main surface and the emissivity of the surface of the rotor at a portion facing the first main surface are higher than any of the emissivity of the second main surface and the emissivity of the third main surface. [Appended Note 9] The molecular pump according to any one of appended claims 1 to 8, wherein the sensor head extends so as to circulate in a circumferential direction that coincides with the rotation direction of the rotor. [Appended Note 10] The molecular pump according to any one of appended claims 1 to 9, wherein the shortest distance from an arbitrary point on the first main surface to the surface of the rotor is substantially the same over the entire first main surface.

[0074] (Other forms, etc.) In the above-described embodiments of the present invention, as a representative example of the molecular pump, the case where the present invention is applied to a composite turbo molecular pump including a turbo molecular pump section and a screw groove vacuum pump section has been illustrated and described. However, the present invention can naturally be applied to a molecular pump having only a turbo molecular pump section and not having a screw groove vacuum pump section, or a molecular pump having only a screw groove vacuum pump section and not having a turbo molecular pump section.

[0075] In addition, the characteristic configurations disclosed in the above-described embodiments of the present invention can be combined with each other as long as they do not depart from the gist of the present invention.

[0076] Thus, all the above-described embodiments disclosed this time are illustrative in every respect and not restrictive. The technical scope of the present invention is defined by the scope of the claims, and includes all modifications within the meaning and scope equivalent to the description of the claims.

Explanation of Reference Numerals

[0077] 1 molecular pump, 10A turbo molecular pump section, 10B screw groove vacuum pump section, 20 case, 21 intake port, 30 base, 31 exhaust port, 40 stator, 41 stator disk, 42 holding member, 43 stator base, 45 stationary blade section, 47 screw groove section, 50 rotor, 51 rotor disk, 52 cylindrical section, 54 hub section, 54a recess, 54a1 corner, 55 moving blade section, 60 rotation drive mechanism, 61 output shaft, 62 housing, 70 detection unit, 71 sensor head, 71a first main surface, 71b second main surface, 72 sensor base, 72a third main surface, 72b fourth main surface, 73 connecting section, 73a heat insulating bolt, 73b heat insulating washer, 74 first temperature sensor, 75 second temperature sensor, 80 pressure detection section, 90 arithmetic section, RA rotation shaft.

Claims

1. A rotary drive mechanism having an output shaft, A rotor that is fixed to the output shaft and is rotationally driven by the rotary drive mechanism, A stator disposed opposite to the rotor along the extending direction of the output shaft, A casing that houses the rotor and to which the stator is fixed, and that is provided with an air inlet and an air outlet so as to be spaced apart from each other in the extending direction of the output shaft, A detection unit for detecting a temperature necessary for estimating the temperature of the rotor, A pressure detection unit for detecting the ambient pressure of the detection unit, An arithmetic unit for calculating an estimated value of the temperature of the rotor, and comprising, The detection unit, A sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, A sensor base including a third main surface facing the second main surface, A connecting portion for connecting the sensor head and the sensor base so as to maintain a state in which the second main surface and the third main surface face each other, A first temperature sensor provided on the sensor head, A second temperature sensor provided on the sensor base, and having, The detection unit is configured such that the form factor of the surface of the rotor as viewed from the first main surface is substantially 1, and the form factor of the third main surface as viewed from the second main surface is substantially 1, The arithmetic unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit. A molecular pump.

2. A rotary drive mechanism having an output shaft, A rotor that is fixed to the output shaft and is rotationally driven by the rotary drive mechanism, A stator disposed opposite to the rotor along the extending direction of the output shaft, A casing that houses the rotor and to which the stator is fixed, and that is provided with an air inlet and an air outlet so as to be spaced apart from each other in the extending direction of the output shaft, A detection unit for detecting a temperature necessary for estimating the temperature of the rotor, A pressure detection unit for detecting the ambient pressure of the detection unit, An arithmetic unit for calculating an estimated value of the temperature of the rotor, and comprising, The detection unit, A sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface, A sensor base including a third main surface facing the second main surface, A connecting portion that connects the sensor head and the sensor base to hold the state in which the second main surface and the third main surface face each other; A first temperature sensor provided on the sensor head; A second temperature sensor provided on the sensor base, and having; The detection unit is configured such that the first main surface faces substantially only the surface of the rotor, and the second main surface faces substantially only the third main surface; A molecular pump in which the calculation unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit.

3. A rotary drive mechanism having an output shaft; A rotor that is fixed to the output shaft and is rotationally driven by the rotary drive mechanism; A stator disposed to face the rotor along the extending direction of the output shaft; A casing that houses the rotor and to which the stator is fixed, and that is provided with an intake port and an exhaust port so as to be spaced apart from each other in the extending direction of the output shaft; A detection unit for detecting a temperature necessary for estimating the temperature of the rotor; A pressure detection unit for detecting the ambient pressure of the detection unit; And a calculation unit for calculating an estimated value of the temperature of the rotor, The detection unit includes: A sensor head including a first main surface facing the surface of the rotor and a second main surface located on the side opposite to the first main surface; A sensor base including a third main surface facing the second main surface; A connecting portion that connects the sensor head and the sensor base to hold the state in which the second main surface and the third main surface face each other; A first temperature sensor provided on the sensor head; A second temperature sensor provided on the sensor base, and having; The detection unit is configured such that the sum of the heat transfer amount due to radiation from the rotor to the sensor head and the heat transfer amount due to gas heat conduction from the rotor to the sensor head is substantially equal to the sum of the heat transfer amount due to radiation from the sensor head to the sensor base, the heat transfer amount due to gas heat conduction from the sensor head to the sensor base, and the heat transfer amount due to solid heat conduction from the sensor head to the sensor base via the connecting portion. The molecular pump, wherein the arithmetic unit calculates an estimated value of the temperature of the rotor based on the detection information detected by the first temperature sensor, the detection information detected by the second temperature sensor, and the detection information detected by the pressure detection unit.

4. The rotary drive mechanism further includes a housing that houses at least a part of the output shaft. The molecular pump according to any one of claims 1 to 3, wherein the sensor base further includes a fourth main surface that is located on the side opposite to the third main surface and contacts the housing.

5. The housing is a bottomed substantially cylindrical shape arranged such that the central axis of the housing overlaps with the output shaft. One end of the output shaft is arranged outside the housing. The rotor is fixed to the one end of the output shaft and has a hub portion that surrounds the one end of the output shaft. A concave portion recessed in a direction away from the housing is provided at the center of the axial end surface on the side of the hub portion facing the housing. The end portion of the housing on the one end side of the output shaft is surrounded by the concave portion. The molecular pump according to claim 4, wherein the detection unit is arranged between the hub portion and the housing so as to face a corner portion that is a boundary between the bottom surface and the inner peripheral surface of the concave portion.

6. The molecular pump according to claim 4, wherein the detection unit is arranged on a flow path of purge gas flowing through a space between the rotor and the housing.

7. The rotary drive mechanism further includes a housing that houses at least a part of the output shaft. The molecular pump according to any one of claims 1 to 3, wherein at least a part of the sensor base is constituted by a part of the housing.

8. The housing is a bottomed substantially cylindrical shape arranged such that the central axis of the housing overlaps with the output shaft. One end of the output shaft is arranged outside the housing. The rotor is fixed to the one end of the output shaft and has a hub portion that surrounds the one end of the output shaft. A concave portion recessed in a direction away from the housing is provided at the center of the axial end surface on the side of the hub portion facing the housing. The end portion of the housing on the one end side of the output shaft is surrounded by the concave portion. The molecular pump according to claim 7, wherein the detection unit is disposed between the hub portion and the housing so as to face a corner portion that is a boundary portion between the bottom surface and the inner peripheral surface of the concave portion.

9. The molecular pump according to claim 7, wherein the detection unit is disposed on a flow path of purge gas flowing through a space between the rotor and the housing.

10. The molecular pump according to any one of claims 1 to 3, wherein the emissivity of the first main surface and the emissivity of the surface of the rotor at a portion facing the first main surface are higher than any of the emissivity of the second main surface and the emissivity of the third main surface.

11. The molecular pump according to any one of claims 1 to 3, wherein the sensor head extends so as to circulate in a circumferential direction that coincides with the rotation direction of the rotor.

12. The molecular pump according to any one of claims 1 to 3, wherein the shortest distance from an arbitrary point on the first main surface to the surface of the rotor is substantially the same over the entire first main surface.

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