Molecular pump

Abstract

This molecular pump (1) comprises a rotation drive mechanism (60), a rotor (50), a stator, a detection unit (70), a pressure detection unit, and a calculation unit. The detection unit (70) includes: a sensor head (71) that includes a first main surface (71a) facing the surface of the rotor (50) and a second main surface (71b) on the opposite side from the first main surface, and is provided with a first temperature sensor (74); a sensor base (72) that includes a third main surface (72a) facing the second main surface (71b) and is provided with a second temperature sensor (75); and a connection part (73). The detection unit (70) is configured such that the shape factor of the surface of the rotor (50) as viewed from the first main surface (71a) is substantially 1, and the shape factor of the third main surface (72a) as viewed from the second main surface (71b) is substantially 1. The calculation unit calculates an estimated value 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 unit.

Description

Molecular Pump

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

[0002] Molecular pumps, a type of vacuum pump, are classified as mechanical momentum transport vacuum pumps in the international standard (ISO 3529-2:2020) and its corresponding standard, the Japanese Industrial Standard (JIS Z 8126-2:2023). This classification also includes turbomolecular pumps and combined turbomolecular pumps. Hereinafter, these vacuum pumps will be collectively referred to as molecular pumps.

[0003] Molecular pumps are mechanical momentum transport vacuum pumps for creating pressure conditions below medium vacuum, and are attached to various processing equipment such as semiconductor manufacturing equipment, various analytical equipment, electron microscopes, etc. Molecular pumps mainly comprise a rotor, a stator, and a rotary drive mechanism for rotating the rotor at high speed.

[0004] In a molecular pump, gas molecules entering through an intake port are sent out toward an exhaust port by rotating a rotor at high speed.

[0005] When the molecular pump is continuously used, stress is applied to the rotor in the circumferential direction due to the high-speed rotational drive described above, which causes creep elongation. If the creep elongation amount exceeds a predetermined value, there is a risk that the rotor and the stator located outside of it will come into contact with each other.

[0006] The creep elongation of the rotor is closely related to the rotor temperature. If the rotor temperature could be constantly monitored, it would be possible to estimate the creep elongation, and ultimately to predict when the molecular pump would require maintenance. Therefore, a molecular pump equipped with a detection unit capable of detecting the rotor temperature is desired.

[0007] In this regard, if a non-contact infrared thermometer is used as such a detection unit, precise temperature measurement becomes possible regardless of the conditions of use of the molecular pump. However, because infrared thermometers are quite large, it is difficult to incorporate them into molecular pumps. In addition, because infrared thermometers are expensive devices, adopting them would significantly increase the manufacturing costs of the molecular pump. Therefore, adopting a non-contact detection unit is not very practical, and there is a need to adopt a detection unit with a simpler configuration.

[0008] A molecular pump employing such a detection unit is disclosed, for example, in International Publication No. 2010 / 021307 (Patent Document 1). The molecular pump disclosed in this publication has two parallel heat transfer paths between the rotor and the stator: one that passes through the detection unit and one that does not. The detection unit and the stator are each equipped with a first temperature sensor and a second temperature sensor. Under this configuration, the molecular pump disclosed in this publication calculates the rotor temperature by linearly extrapolating the measurements of the two temperature sensors under the assumption that the amount of heat transfer between the rotor, the detection unit, and the stator is proportional to the temperature difference.

[0009] International Publication No. 2010 / 021307

[0010] In the molecular pump disclosed in the above publication, the amount of heat transfer is not necessarily proportional to the temperature difference due to the existence of heat transfer paths such as radiation and rarefied gas thermal conduction, making it difficult to precisely detect the rotor temperature using the contact-type detection unit provided in the molecular pump disclosed in the above publication.

[0011] Furthermore, in the molecular pump disclosed in the above publication, the unknown constants appearing in the linear extrapolation formula must be determined in advance by measurement tests or the like. These unknown constants depend on the operating conditions of the molecular pump, which vary greatly from time to time. Therefore, although it is necessary to determine the unknown constants corresponding to the operating conditions each time, this is not very practical and lacks versatility and convenience. As such, it is difficult for conventionally known molecular pumps to achieve both a simple configuration and the ability to accurately and easily calculate the rotor temperature.

[0012] Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a molecular pump that can precisely and easily calculate the temperature of the rotor with a simple configuration.

[0013] A molecular pump according to a first 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 the rotor along the extension direction of the output shaft, a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the extension direction of the output shaft, a detection unit for detecting a temperature required to estimate 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 rotor temperature. 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 opposite side to the first main surface, a sensor base including a third main surface facing the second main surface, a connecting unit that connects the sensor head and the sensor base to maintain the second main surface and the third main surface facing each other, a first temperature sensor provided in the sensor head, and a second temperature sensor provided in the sensor base. The detection unit is configured so that a geometric factor of the surface of the rotor as viewed from the first main surface is substantially 1, and a geometric 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 detection information detected by the first temperature sensor, detection information detected by the second temperature sensor, and detection information detected by the pressure detection unit.

[0014] A molecular pump according to a second 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 the rotor along the extension direction of the output shaft, a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the extension direction of the output shaft, a detection unit for detecting a temperature required to estimate 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 rotor temperature. 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 opposite side to the first main surface, a sensor base including a third main surface facing the second main surface, a connecting unit connecting the sensor head and the sensor base to maintain the second main surface and the third main surface facing each other, a first temperature sensor provided in the sensor head, and a second temperature sensor provided in the sensor base. The detection unit is configured such that the first main surface faces substantially only the front surface of the rotor, and the second main surface faces substantially 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 detection information detected by the first temperature sensor, detection information detected by the second temperature sensor, and detection information detected by the pressure detection unit.

[0015] A molecular pump according to a 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 the rotor along the extension direction of the output shaft, a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the extension direction of the output shaft, a detection unit for detecting a temperature required to estimate 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 rotor temperature. 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 opposite side to the first main surface, a sensor base including a third main surface facing the second main surface, a connecting unit that connects the sensor head and the sensor base to maintain the second main surface and the third main surface facing each other, a first temperature sensor provided in the sensor head, and a second temperature sensor provided in the sensor base. The detection unit is configured so that the sum of the amount of heat transferred by radiation from the rotor to the sensor head and the amount of heat transferred by gas thermal conduction from the rotor to the sensor head is substantially equal to the sum of the amount of heat transferred by radiation from the sensor head to the sensor base, the amount of heat transferred by gas thermal conduction from the sensor head to the sensor base, and the amount of heat transferred by solid thermal 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.

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

[0017] Fig. 2 is a schematic cross-sectional view of a molecular pump according to an embodiment. Fig. 3 is an enlarged cross-sectional view of the vicinity of a detection unit shown in Fig. 1. Fig. 4 is a diagram showing the configuration of functional blocks of the molecular pump shown in Fig. 1. Fig. 5 is a schematic diagram for explaining a heat transfer path from a rotor to a sensor base in the molecular pump shown in Fig. 1. Fig. 6 is a graph showing measurement results of a verification test. Fig. 7 is a table showing measurement results of a verification test.

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown below exemplify the case where the present invention is applied to a compound turbomolecular pump (a type of molecular pump) equipped with a turbomolecular pump section and a thread groove vacuum pump section. In the embodiments shown below, the same or common parts are given the same reference numerals in the drawings, and their description will not be repeated.

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

[0020] As shown in Fig. 1, the molecular pump 1 includes a turbomolecular pump section 10A and a thread groove vacuum pump section 10B as components for realizing the exhaust function, and has an overall substantially cylindrical outer shape. The molecular pump 1 includes a case 20, a base 30, a stator 40, a rotor 50, a rotation drive mechanism 60, a detection unit 70, a pressure detection section 80, and a calculation section 90 (see Fig. 3). The detection unit 70, the pressure detection section 80, and the calculation section 90 are used to estimate the temperature of the rotor 50, and details thereof will be described later.

[0021] The casing of the molecular pump 1 is composed of a case 20, a base 30, and a stator base 43 of 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 positioned apart from each other in the extension direction of an output shaft 61 of a rotation drive mechanism 60, which will be described later.

[0022] The space inside the casing mainly accommodates the remaining stator disk 41 and holding member 42 of the stator 40, the rotor disk 51 and cylindrical portion 52 that constitute the rotor 50, and the rotation drive mechanism 60. An exhaust path is provided inside the casing to connect the intake port 21 and the exhaust port 31.

[0023] The turbomolecular pump section 10A is mainly composed of a stator disk 41 of the stator 40 and a rotor disk 51 of the rotor 50. The stator disk 41 is provided with a plurality of stationary blade sections 45. The rotor disk 51 is provided with a plurality of moving blade sections 55. The plurality of stationary blade sections 45 and the plurality of moving blade sections 55 are arranged opposite each other, and the rotor disk 51 rotates at high speed, causing the turbomolecular pump section 10A to perform an exhaust function.

[0024] The thread groove vacuum pump section 10B is mainly composed of a stator base 43 of the stator 40 and a cylindrical portion 52 of the rotor 50. A thread groove section 47 is provided on the stator base 43. The cylindrical portion 52 is disposed opposite the thread groove section 47, and the cylindrical portion 52 rotates at high speed, causing the thread groove vacuum pump section 10B to perform an exhaust function.

[0025] The turbomolecular pump section 10A is disposed in a position in the exhaust path downstream of the intake port 21. The thread groove vacuum pump section 10B is disposed in a position in the exhaust path downstream of the turbomolecular pump section 10A and upstream of the exhaust port 31. As a result, in the molecular pump 1, the gas to be exhausted is exhausted in the order of the intake port 21, turbomolecular pump section 10A, thread groove vacuum pump section 10B, and exhaust port 31.

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

[0027] The rotary drive mechanism 60 includes an output shaft 61 rotatably supported by bearings, a motor that rotates the output shaft 61, and a housing 62 that accommodates a portion of the output shaft 61, the bearing, and the motor. The housing 62 is substantially cylindrical and has a bottom. The housing 62 is positioned so that its central axis overlaps with the output shaft 61.

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

[0029] As described above, the rotor 50 has the rotor disk 51 and the cylindrical portion 52, and is configured as an integrated metal member comprising the rotor disk 51 and the cylindrical portion 52. In this embodiment, the rotor 50 is configured as an aluminum member.

[0030] The rotor 50 is fixed to the output shaft 61 of the rotation drive mechanism 60 by inserting and fitting the output shaft 61 into a hole provided in the center 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 multiple rotor blade stages arranged along the direction in which the output shaft 61 of the rotation drive mechanism 60 extends, with multiple rotor blade portions 55 lined up along the circumferential direction.

[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 portion of the output shaft 61 of the rotation drive mechanism 60 described above and surrounds this upper end portion. The plurality of moving blade portions 55 protrude outward from the hub portion 54 along the radial direction of the rotor disk 51.

[0032] A recess 54a (see FIG. 2, described later) recessed in a direction away from the housing 62 is provided in the center of the axial end face of the hub portion 54 that faces the housing 62 of the rotation drive mechanism 60. The upper end 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 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, the detailed configuration of the detection unit 70 and its vicinity will be described with reference to Figs. 2 to 4 and the above-mentioned Fig. 1. Note that Fig. 4 shows simplified shapes of the rotor 50, sensor head 71, sensor base 72, and connecting portion 73.

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

[0035] 2, the detection unit 70 has 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 54a1 that is the boundary between the bottom surface and the inner circumferential surface of the recess 54a provided in the hub portion 54. The detection unit 70 is used to detect a temperature required to estimate the temperature of the rotor 50.

[0036] 2, the sensor head 71 is an annular plate-shaped component curved to fit the curved surface of the corner portion 54a1. More specifically, the sensor head 71 extends around the rotor 50 in a 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 opposite side of the first main surface 71a.

[0037] The sensor head 71 is configured so 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 constant over the entire first main surface 71a. This improves the accuracy of temperature estimation of the rotor 50 using the detection unit 70, etc., as will be described in detail later.

[0038] 2, the sensor base 72 is an annular plate-shaped component attached to the upper end of the housing 62. More specifically, the sensor base 72 extends around in a circumferential direction that coincides with the rotational direction DR of the rotor 50. The sensor base 72 includes a third main surface 72a that faces the second main surface 71b of the sensor head 71, and a fourth main surface 72b located on the opposite side from the third main surface 72a. The sensor base 72 is attached to the housing 62 with at least a portion 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. In this embodiment, the sensor head 71 and the sensor base 72 are made of aluminum. The first main surface 71 a of the sensor head 71 and at least a portion of the surface of the rotor 50 facing the first main surface 71 a are anodized to improve emissivity. This results in the emissivity of these portions being higher than both the emissivity of the second main surface 71 b of the sensor head 71 and the emissivity of the third main surface 72 a of the sensor base 72. This configuration improves the accuracy of temperature estimation of the rotor 50 using the detection unit 70, etc., as 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 are held in a state where they face each other.

[0041] Although the specific configuration of the connecting portion 73 is not particularly limited, it is preferable that the connecting portion 73 has excellent heat insulating properties. In this embodiment, an insulating bolt 73 a and an insulating washer 73 b are used as the connecting portion 73.

[0042] There may be one or more connecting portions 73. In this embodiment, four connecting portions 73 are arranged at positions rotationally symmetrical by 90° when viewed along the axial direction of the rotation drive mechanism 60.

[0043] A first temperature sensor 74 is provided at a predetermined position on the sensor head 71. The first temperature sensor 74 detects the temperature of the sensor head 71 and outputs the detected information to a calculation unit 90, which will be described later. A second temperature sensor 75 is provided at a predetermined position on the sensor base 72. The second temperature sensor 75 detects the temperature of the sensor base 72 and outputs the detected information to the calculation unit 90. In this embodiment, the first temperature sensor 74 and the second temperature sensor 75 are contact-type temperature sensors.

[0044] A purge gas is supplied to the molecular pump 1 (see the arrows in FIG. 2 ). More specifically, the purge gas is supplied to the molecular pump 1 so that it flows along the output shaft 61 of the rotary drive mechanism 60, then through the space between the rotor 50 and the housing 62, and then toward the exhaust port 31. By supplying the purge gas in this manner, if the process gas drawn in through the intake port 21 is a corrosive gas, the internal components of the rotary drive mechanism 60 can be protected from the process gas. The detection unit 70 is disposed in the purge gas flow path, including the space between the rotor 50 and the housing 62. This protects the detection unit 70 from the process gas if the process gas is a corrosive gas. Furthermore, by filling the area around the detection unit 70 with a known gas in this manner, the amount of heat transfer due to gas thermal conduction can be more easily estimated. The type of purge gas is not particularly limited as long as it is an inert gas; for example, nitrogen gas is preferably used.

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

[0046] A calculation unit 90 is provided in the internal space of the casing of the molecular pump 1 or outside the casing. 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] 2, in the molecular pump 1 according to this embodiment, the first main surface 71a of the sensor head 71 faces substantially only the surface of the rotor 50. In addition, the second main surface 71b of the sensor head 71 faces substantially only the third main surface 72a of the sensor base 72.

[0048] With this configuration, the geometric factor of the surface of the rotor 50 as viewed from the first main surface 71a of the sensor head 71 can be set to substantially 1, and the geometric factor of the third main surface 72a of the sensor base 72 as viewed from the second main surface 71b of the sensor head 71 can be set to substantially 1. The geometric factor refers to the proportion of radiant energy emitted from a surface that reaches another surface.

[0049] With the above-described configuration, it is possible to provide a molecular pump 1 that can precisely and easily calculate the temperature of the rotor 50 with a simple configuration, which will be described in detail below with reference to FIG.

[0050] As shown in Figure 4, in the molecular pump 1 of this embodiment, the forms of heat transfer in and out of the sensor head 71 include 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 part 73.

[0051] Let Qe1 be the amount of heat transferred to the sensor head 71 by radiation from the rotor 50, Qg2 be the amount of heat transferred to the sensor head 71 by gas thermal conduction from the rotor 50, Qe3 be the amount of heat transferred to the sensor base 72 by radiation from the sensor head 71, Qg4 be the amount of heat transferred to the sensor base 72 by gas thermal conduction from the sensor head 71, and Qc5 be the amount of heat transferred to the sensor base 72 via the connecting portion 73 by solid thermal conduction from the sensor head 71. In this case, as shown in the following equation (1), the sum of the heat transfer amounts Qe1 and Qg2 is substantially equal to the sum of the heat transfer amounts Qe3, Qg4, and Qc5. This is because configuring the detection unit 70 to have the above-mentioned view factors eliminates disturbances other than the above five forms of heat transfer, and thereby simplifies the flow of heat in and out of the sensor head 71 to the above five forms of heat transfer.

[0052]

[0053] Here, when one of two objects faces substantially only the other, the amount of heat transfer by radiation Qe and the amount of heat transfer by gas thermal conduction Qg between these two objects are generally described by the following equations (2) and (3), respectively. 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 one object. T2 is the temperature of the other object. S1 is the surface area of ​​the one object. x is the distance between the two objects. L is the mean free path of the gas, 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 with a value of 2.4. γ2 is a constant with a value of 1.92.

[0054]

[0055]

[0056] Furthermore, the amount of heat transfer Qc due to solid thermal conduction of the member connecting the two objects is generally described by the following formula (4): where λ is the thermal conductivity of the member connecting the two objects, A is the cross-sectional area of ​​the member connecting the two objects, and δ is the length of the member connecting the two objects.

[0057]

[0058] From the above, the heat transfer amount Qe1 is expressed as a function of the estimated value Tr of the temperature 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 value Tr of the temperature 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 section 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 calculation unit 90 acquires the detection information detected by 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 this detection information and the above formula (1), thereby deriving the estimated value T ｒ The accuracy of the estimation of the temperature of the rotor 50 in the molecular pump 1 according to the present embodiment has been confirmed by a verification test described later.

[0060] Furthermore, in the molecular pump 1 according to this embodiment, as described above, the detection unit 70 is composed of the sensor head 71, the sensor base 72, the connecting portion 73, and the first temperature sensor 74 and the second temperature sensor 75, which are contact-type temperature sensors. By configuring it in this way, it is possible to obtain a detection unit that is not only cheaper but also simpler and more compact than when a non-contact type temperature sensor is used as the detection unit, and a molecular pump equipped with the same.

[0061] Furthermore, in the molecular pump 1 according to this embodiment, the calculation unit 90 estimates the temperature of the rotor 50 using equation (1), which is composed only of constants that are not dependent on the use conditions of the molecular pump 1. Therefore, when calculating the temperature of the rotor 50, it is not necessary to determine unknown constants corresponding to the use conditions of the molecular pump 1 each time, and the molecular pump can be made to be highly versatile and convenient.

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

[0063] Furthermore, in the molecular pump 1 according to this embodiment, as described above, the sensor head 71 is configured so that the shortest distance from any point on the first main surface 71a of the sensor head 71 to the surface of the rotor 50 is substantially constant over the entire first main surface 71a. By configuring it in this way, x in equation (3), which is the distance between the rotor 50 and the first main surface 71a, can be made a constant. This makes it 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 any 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 constant over the entire second main surface 71b. In this regard, since x in equation (3) (i.e., the distance between the second main surface 71b and the third main surface 72a) is a relatively large value, even if the shortest distance is not substantially constant over the entire second main surface 71b, the temperature of the rotor 50 can be calculated with sufficiently high accuracy by performing a predetermined calculation using the average value of the distances from any point on the second main surface 71b of the sensor head 71 to the third main surface 72a of the sensor base 72.

[0065] Furthermore, in the molecular pump 1 according to this embodiment, as described above, the emissivity of the first main surface 71 a 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 71 a are higher than the emissivity of the second main surface 71 b of the sensor head 71 and the emissivity of the third main surface 72 a of the sensor base 72.

[0066] This configuration can further promote the transfer of heat by radiation from the rotor 50 to the sensor head 71. As a result, the temperature difference between the sensor head 71 and the sensor base 72 increases, making it possible to improve the accuracy of the temperature estimation of the rotor 50.

[0067] In the molecular pump 1 according to the present embodiment described above, the sensor base 72 is a separate component from the housing 62, but at least a portion of the sensor base 72 (i.e., a portion or the entire sensor base 72) may be configured as part of the housing 62.

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

[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 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 actual measured value Trm of the rotor 50 temperature and the estimated value Tr of the rotor 50 temperature during a predetermined operating time of the molecular pump 1.

[0070] From the results shown in Figures 5 and 6, it was found that the estimated value Tr of the temperature of the rotor 50 using the detection unit 70, etc., did not differ significantly from the actual measured value Trm of the temperature of the rotor 50 using an infrared radiation thermometer, and that the difference between these estimated value Tr and actual measured value Trm was at most about 2°C.

[0071] From the above results, it was found that by configuring the molecular pump 1 according to this embodiment, it is possible to precisely calculate the estimated value of the temperature of the rotor 50.

[0072] (Additional Note) The characteristic configuration of the molecular pump disclosed in the above-described embodiment can be summarized as follows.

[0073] a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the direction of extension of the output shaft; a detection unit that detects a temperature required to estimate a temperature of the rotor; a pressure detection section that detects an ambient pressure of the detection unit; and a calculation section that calculates an estimated value of the temperature of the rotor, wherein the detection unit has: a sensor head including a first main surface that faces a surface of the rotor and a second main surface located on the opposite side to the first main surface; a sensor base including a third main surface that faces the second main surface; a connection section that connects 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 in the sensor head; and a second temperature sensor provided in the sensor base, the detection unit is configured so that a geometric factor of the surface of the rotor as viewed from the first main surface is substantially 1 and a geometric factor of the third main surface as viewed from the second main surface is substantially 1; and the calculation unit calculates an estimated value of the temperature of the rotor based on detection information detected by the first temperature sensor, detection information detected by the second temperature sensor, and detection information detected by the pressure detection unit.

[0074] a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the direction of extension of the output shaft; a detection unit that detects a temperature required to estimate a temperature of the rotor; a pressure detection section that detects an ambient pressure of the detection unit; and a calculation section that calculates an estimated value of the temperature of the rotor, wherein the detection unit has: a sensor head including a first main surface that faces a surface of the rotor and a second main surface located on the opposite side to the first main surface; a sensor base including a third main surface that faces the second main surface; a connection section that connects 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 in the sensor head; and a second temperature sensor provided in the sensor base, the detection unit is configured so 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, and the calculation unit calculates an estimated value of the temperature of the rotor based on detection information detected by the first temperature sensor, detection information detected by the second temperature sensor, and detection information detected by the pressure detection unit.

[0075] a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the direction of extension of the output shaft; a detection unit that detects a temperature required to estimate a temperature of the rotor; a pressure detection section that detects an ambient pressure of the detection unit; and a calculation section that calculates an estimated value of the temperature of the rotor, wherein the detection unit has: a sensor head including a first main surface that faces a surface of the rotor and a second main surface located on the opposite side to the first main surface; a sensor base including a third main surface that faces the second main surface; a connection section that connects 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 in the sensor head; and a second temperature sensor provided in the sensor base, a molecular pump in which the detection unit is configured so that the sum of the amount of heat transferred by radiation from the rotor to the sensor head and the amount of heat transferred by gas thermal conduction from the rotor to the sensor head is substantially equal to the sum of the amount of heat transferred by radiation from the sensor head to the sensor base, the amount of heat transferred by gas thermal conduction from the sensor head to the sensor base, and the amount of heat transferred by solid thermal conduction from the sensor head to the sensor base via the connecting portion; and 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.

[0076] [Supplementary Note 4] The molecular pump according to any one of Supplementary Notes 1 to 3, wherein the rotary drive mechanism further has a housing that accommodates at least a portion of the output shaft, and the sensor base further includes a fourth main surface located opposite the third main surface and in contact with the housing.

[0077] [Supplementary Note 5] The molecular pump according to any one of Supplementary Notes 1 to 3, wherein the rotary drive mechanism further has a housing that accommodates at least a portion of the output shaft, and at least a portion of the sensor base is formed by a portion of the housing.

[0078] [Appendix 6] A molecular pump according to appendix 4 or 5, wherein the housing is a substantially cylindrical housing with a bottom arranged so that a 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 surrounding the one end of the output shaft, a recess recessed in a direction away from the housing is provided in a central portion of an axial end face of the hub portion facing the housing, an end of the housing on the one end side of the output shaft is surrounded by the recess, and the detection unit is arranged between the hub portion and the housing so as to face a corner that is a boundary between a bottom surface and an inner peripheral surface of the recess.

[0079] [Supplementary Note 7] The molecular pump according to any one of Supplementary Notes 4 to 6, wherein the detection unit is disposed on a flow path of a purge gas flowing through the space between the rotor and the housing.

[0080] [Supplementary Note 8] The molecular pump according to any one of Supplementary Notes 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 the emissivity of the second main surface and the emissivity of the third main surface.

[0081] [Supplementary Note 9] The molecular pump according to any one of Supplementary Notes 1 to 8, wherein the sensor head extends so as to go around in a circumferential direction that coincides with a rotation direction of the rotor.

[0082] [Supplementary Note 10] The molecular pump according to any one of Supplementary Notes 1 to 9, wherein the shortest distance from any point on the first main surface to the surface of the rotor is substantially constant over the entire first main surface.

[0083] (Other embodiments, etc.) In the above-described embodiments of the present invention, the present invention has been described as being applied to a combined turbomolecular pump having a turbomolecular pump section and a thread groove vacuum pump section as a representative example of a molecular pump, but the present invention can naturally also be applied to a molecular pump having only a turbomolecular pump section and not a thread groove vacuum pump section, or a molecular pump having only a thread groove vacuum pump section and not a turbomolecular pump section.

[0084] Furthermore, the characteristic configurations disclosed in the above-described embodiments of the present invention can be combined with each other without departing from the spirit of the present invention.

[0085] As such, the above-described embodiments disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims.

[0086] 1 Molecular pump, 10A Turbo molecular pump section, 10B Thread 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 Thread groove section, 50 Rotor, 51 Rotor disk, 52 Cylindrical section, 54 Hub section, 54a Recessed section, 54a1 Corner section, 55 Rotor 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 Insulating bolt, 73b Insulating washer, 74 First temperature sensor, 75 Second temperature sensor, 80 Pressure detection section, 90 Calculation unit, RA rotation axis.

Claims

a rotor that is fixed to the output shaft and thereby driven to rotate by the rotation drive mechanism; a stator disposed facing the rotor along the extension direction of the output shaft; a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the extension direction of the output shaft; a detection unit for detecting a temperature required to estimate a temperature of the rotor; a pressure detection section that detects an ambient pressure of the detection unit; and a calculation section that calculates an estimated value of the temperature of the rotor, the detection unit having: a sensor head including a first main surface that faces a surface of the rotor and a second main surface located on the opposite side to the first main surface; a sensor base including a third main surface that faces the second main surface; a connection section that connects the sensor head and the sensor base to maintain a state in which the second main surface and the third main surface are opposed to each other; a first temperature sensor provided in the sensor head; and a second temperature sensor provided in the sensor base, a molecular pump, wherein the detection unit is configured so that a geometric factor of the surface of the rotor as viewed from the first main surface is substantially 1 and a geometric factor of the third main surface as viewed from the second main surface is substantially 1, and the calculation unit calculates an estimate of a temperature of the rotor based on 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.

2. A sensor device comprising: a rotary drive mechanism having an output shaft; a rotor fixed to the output shaft and rotated by the rotary drive mechanism; a stator disposed facing the rotor along the extension direction of the output shaft; a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the extension direction of the output shaft; a detection unit for detecting a temperature required to estimate a temperature of the rotor; a pressure detection section that detects an ambient pressure of the detection unit; and a calculation section that calculates an estimated value of the temperature of the rotor, the detection unit comprising: a sensor head including a first main surface facing a surface of the rotor and a second main surface located on the opposite side to the first main surface; a sensor base including a third main surface facing the second main surface; a connection section that connects the sensor head and the sensor base to maintain a state in which the second main surface and the third main surface are opposed to each other; a first temperature sensor provided in the sensor head; and a second temperature sensor provided in the sensor base, a molecular pump, wherein the detection unit is configured so 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, and the calculation unit calculates an estimate of the temperature of the rotor based on detection information detected by the first temperature sensor, detection information detected by the second temperature sensor, and detection information detected by the pressure detection unit.

3. A rotary drive mechanism having an output shaft; a rotor fixed to the output shaft and rotated by the rotary drive mechanism; a stator disposed facing the rotor along the extension direction of the output shaft; a casing that houses the rotor and to which the stator is fixed, the casing having an intake port and an exhaust port spaced apart from each other in the extension direction of the output shaft; a detection unit for detecting a temperature required to estimate a temperature of the rotor; a pressure detection section that detects an ambient pressure of the detection unit; and a calculation section that calculates an estimated value of the temperature of the rotor, wherein the detection unit has: a sensor head including a first main surface facing a surface of the rotor and a second main surface located on the opposite side to the first main surface; a sensor base including a third main surface facing the second main surface; a connection section that connects the sensor head and the sensor base to maintain a state in which the second main surface and the third main surface are opposed to each other; a first temperature sensor provided in the sensor head; and a second temperature sensor provided in the sensor base, A molecular pump, wherein the detection unit is configured so that a sum of the amount of heat transfer by radiation from the rotor to the sensor head and the amount of heat transfer by gas thermal conduction from the rotor to the sensor head is substantially equal to a sum of the amount of heat transfer by radiation from the sensor head to the sensor base, the amount of heat transfer by gas thermal conduction from the sensor head to the sensor base, and the amount of heat transfer by solid thermal conduction from the sensor head to the sensor base via the connecting portion, and the calculation unit calculates an estimate 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. A molecular pump as described in any one of claims 1 to 3, wherein the rotary drive mechanism further has a housing that accommodates at least a portion of the output shaft, and the sensor base further includes a fourth main surface located opposite the third main surface and in contact with the housing.

5. A molecular pump as described in claim 4, wherein the housing is a generally cylindrical housing with a bottom arranged so that a 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 surrounding the one end of the output shaft, a recess is provided in a central portion of the axial end face of the hub portion facing the housing, the recess is recessed in a direction away from the housing, an end of the housing on the one end side of the output shaft is surrounded by the recess, and the detection unit is arranged between the hub portion and the housing so as to face a corner that is the boundary between the bottom surface and the inner circumferential surface of the recess.

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

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

8. A molecular pump as described in claim 7, wherein the housing is a generally cylindrical housing with a bottom arranged so that a 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 surrounding the one end of the output shaft, a recess is provided in a central portion of the axial end face of the hub portion facing the housing, the recess is recessed in a direction away from the housing, an end of the housing on the one end side of the output shaft is surrounded by the recess, and the detection unit is arranged between the hub portion and the housing so as to face a corner that is the boundary between the bottom surface and the inner circumferential surface of the recess.

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

10. A molecular pump as described in any one of claims 1 to 3, wherein the emissivity of the first main surface and the emissivity of the surface of the rotor facing the first main surface are higher than 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 circumferentially surround the rotor in a circumferential direction that coincides with the direction of rotation of the rotor.

12. A molecular pump according to any one of claims 1 to 3, wherein the shortest distance from any point on said first main surface to said surface of said rotor is substantially constant over the entirety of said first main surface.

Images