Vacuum pump and rotating body for vacuum pump

Abstract

To provide a vacuum pump which enables reduction of stress occurring in a coupling portion between a rotating body and a rotary shaft.SOLUTION: A vacuum pump has rotary vanes 102b, 102c at an outer periphery of a rotary vane formation part 217 and includes a rotating body 103 which is fastened to a rotor shaft 113 by bolts 214 and may rotate with the rotor shaft 113. At least one of a fitting hole part 215, which fits with the rotary shaft 113, and through hole parts 216, through which the bolts 214 penetrate, of the rotating body 103 is a stress reduction object part, and the rotating body 103 includes a groove part 218 which reduces stress occurring in the stress reduction object part during rotation of the rotating body 103.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a vacuum pump such as a turbomolecular pump, and a rotating body for a vacuum pump. [Background technology]

[0002] Turbomolecular pumps are generally known as a type of vacuum pump. In these turbomolecular pumps, a motor inside the pump body is energized to rotate rotors, which eject gas molecules from the gas (process gas) drawn into the pump body, thereby discharging the gas. In these turbomolecular pumps, a rotor shaft is coupled to a rotor on which rotor blades are formed, and the motor rotates the rotor shaft and the rotor to perform the evacuation (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-286013 Summary of the Invention [Problem to be solved by the invention]

[0004] In vacuum pumps such as the various turbomolecular pumps described above, the higher the rotation speed of the rotor, the better the pumping performance. However, when the inventors conducted a structural analysis focusing on the joint between the rotor and the rotor shaft, they found that stress concentration is likely to occur at this joint.

[0005] In order to reduce the stress generated at the joint between the rotor and the rotating shaft, it is conceivable to set the rotation speed during rated operation low, but lowering the rotation speed makes it difficult to improve pumping performance. On the other hand, if the rotation speed is increased to improve pumping performance without taking measures against the stress concentration described above, high stress will be generated at the joint between the rotor and the rotating shaft, reducing reliability. Furthermore, because the joint between the rotor and the rotating shaft is a part that has a significant impact on the reliability of the vacuum pump, it is not easy to make a major design change to this joint.

[0006] An object of the present invention is to provide a vacuum pump and a rotor for a vacuum pump that are capable of reducing stress concentration that occurs in a rotor, particularly stress that occurs at the joint between the rotor and the rotating shaft. [Means for solving the problem]

[0007] (1) In order to achieve the above object, the present invention provides a rotor having a rotor on the outer periphery of a cylindrical portion, 1. A vacuum pump having a rotor fastened to a rotary shaft by a fastening means and rotatable together with the rotary shaft, The vacuum pump is characterized in that at least one of the fitting hole portion of the rotating body that fits with the rotating shaft and the through hole portion through which the fastening means passes is a stress reduction target portion, and the rotating body is provided with a groove portion that reduces stress generated in the stress reduction target portion during rotation of the rotating body. (2) Furthermore, in order to achieve the above object, another aspect of the present invention is a vacuum pump as described in (1), characterized in that the groove portion is provided on the outer periphery side of the fitting hole portion or the through hole portion. (3) Furthermore, in order to achieve the above object, another aspect of the present invention is a vacuum pump as described in (1) or (2), characterized in that the groove portion is provided on at least one of the inner circumferential surface or the outer circumferential surface of the rotating body. (4) In order to achieve the above object, another aspect of the present invention is a vacuum pump according to any one of (1) to (3), characterized in that the groove portion has a gently sloping structure at least on the inner peripheral side. (5) Furthermore, in order to achieve the above object, another aspect of the present invention is a vacuum pump described in any one of (1) to (4), characterized in that the groove portion is arranged on the fastening surface of the rotating body or on an extension surface thereof. (6) In order to achieve the above object, another aspect of the present invention is a vacuum pump according to any one of (1) to (5), characterized in that the rotating body is surface-treated and has a counterbore portion on the periphery of at least one of the fitting hole portion and the through-hole portion to avoid contact with the rotating shaft. (7) In order to achieve the above object, another aspect of the present invention is a rotor having a rotor on the outer periphery of a cylindrical portion, A vacuum pump rotor fastened to a rotary shaft by fastening means, At least one of the fitting hole portion that fits with the rotating shaft and the fastening portion to which the fastening means is fastened is a stress reduction target portion, and the rotating body for a vacuum pump is characterized by having a groove portion that reduces stress generated in the stress reduction target portion during rotation. [Effects of the Invention]

[0008] According to the above invention, it is possible to provide a vacuum pump and a rotor for a vacuum pump that are capable of reducing stress generated at the joint between the rotor and the rotating shaft. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view of a turbomolecular pump according to an embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram of an amplifier circuit. [Figure 3] 10 is a time chart showing control when a current command value is larger than a detection value. [Figure 4] 10 is a time chart showing control when a current command value is smaller than a detection value. [Figure 5] FIG. 2 is an enlarged longitudinal sectional view showing a part of FIG. [Figure 6] FIG. 6 is an enlarged longitudinal sectional view of a part of FIG. 5. [Figure 7]2 is an explanatory diagram showing an enlarged view of a groove portion in the turbomolecular pump of FIG. 1. FIG. [Figure 8] 10A and 10B are explanatory diagrams showing modified examples of the groove portion. [Figure 9] FIG. 10(a) is an explanatory diagram showing deflection of a rotating body when no grooves are provided, and FIG. 10(b) is an explanatory diagram showing deflection of a rotating body when grooves are provided. [Figure 10] 10A and 10B are explanatory diagrams showing a schematic view of the work involved in producing a groove portion. [Figure 11] 2 is an enlarged longitudinal sectional view showing a stress control recess formed in a portion surrounded by a circle D in FIG. 1. FIG. [Figure 12] FIG. 10 is a vertical cross-sectional view showing a modified example of the stress control recess. [Figure 13] FIG. 6( a) is an explanatory diagram showing the coupling relationship between the rotating body and the rotor shaft shown in FIG. 1 and FIG. 5, FIG. 6( b) is an explanatory diagram showing a modified example of the rotating body, FIG. 6( c) is an explanatory diagram showing another modified example of the rotating body, and FIG. 6( d) is an explanatory diagram showing yet another modified example of the rotating body. [Figure 14] FIG. 10( a ) is an explanatory diagram showing yet another modified example of the rotating body, (b) is an explanatory diagram showing yet another modified example of the rotating body, and (c) is an explanatory diagram showing yet another modified example of the rotating body. DETAILED DESCRIPTION OF THE INVENTION

[0010] (1) In order to achieve the above object, the present invention provides a rotor having a rotor on the outer periphery of a cylindrical portion, 1. A vacuum pump having a rotor fastened to a rotary shaft by a fastening means and rotatable together with the rotary shaft, At least one of a fitting hole portion of the rotating body that fits with the rotating shaft and a through hole portion through which the fastening means passes is a stress reduction target portion, and the rotating body is provided with a groove portion that reduces stress generated in the stress reduction target portion during rotation of the rotating body. 、 The rotating body a disk portion into which the fitting shaft portion of the rotary shaft is fitted, and a bottom portion is formed by the disk portion; Depression and, Equipped with The groove portion The bottom surface of the disk portion, which is the surface opposite to the bottom a first groove portion formed in the circumferential direction of the recessed portion; The aforementioned bottom The outer periphery ofThe vacuum pump further comprises a second groove portion formed in the circumferential direction. (2) Furthermore, in order to achieve the above object, another aspect of the present invention is a vacuum pump as described in (1), characterized in that the groove portion is provided on the outer periphery side of the fitting hole portion or the through hole portion. (3) Furthermore, in order to achieve the above object, another aspect of the present invention is a vacuum pump as described in (1) or (2), characterized in that the first groove portion has a gently inclined structure at least on the inner peripheral side. (4) Furthermore, in order to achieve the above object, another aspect of the present invention is a vacuum pump described in any one of (1) to (3), characterized in that the first groove portion is arranged on the fastening surface of the rotating body or on an extension surface thereof. (5) In order to achieve the above object, another aspect of the present invention is a vacuum pump according to any one of (1) to (4), characterized in that the rotating body is surface-treated and has a counterbore portion on the periphery of at least one of the fitting hole portion and the through-hole portion to avoid contact with the rotating shaft. (6) In order to achieve the above object, another aspect of the present invention is a rotor having a rotor on the outer periphery of a cylindrical portion, A vacuum pump rotor fastened to a rotary shaft by fastening means, At least one of a fitting hole portion that fits with the rotating shaft and a fastening portion to which the fastening means is fastened is a stress reduction target portion, and the fitting hole portion is provided with a groove portion that reduces stress generated in the stress reduction target portion during rotation, The vacuum pump rotor a disk portion into which the fitting shaft portion of the rotary shaft is fitted, and a bottom portion is formed by the disk portion; Depression and, Equipped with The groove portion The bottom surface of the disk portion, which is the surface opposite to the bottom a first groove portion formed in the circumferential direction of the recessed portion; The aforementioned bottom The outer periphery of The rotor for a vacuum pump is characterized in that it has a second groove portion formed in the circumferential direction.

[0011] A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in FIG. 1. In FIG. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer tube 127. Inside the outer tube 127, a rotor 103 is provided, the rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, etc.), which are turbine blades for sucking in and exhausting gas, formed radially and in multiple stages around its periphery. A rotor shaft 113 (rotating shaft) is attached to the center of this rotor 103, and this rotor shaft 113 is levitated and supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing. The rotor 103 is generally made of metal such as aluminum or an aluminum alloy.

[0012] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each upper radial electromagnet 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on changes in the inductance of the conductive windings, which change according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to the control device 200.

[0013] In this control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in Figure 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0014] The rotor shaft 113 is made of a high magnetic permeability material (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnets 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnets 105 and the lower radial sensors 108 are arranged in the same manner as the upper radial electromagnets 104 and the upper radial sensors 107, and adjust the radial position of the lower side of the rotor shaft 113 in the same manner as the radial position of the upper side.

[0015] Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a highly magnetic permeable material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and an axial position signal is sent to control device 200.

[0016] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disc 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disc 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0017] In this way, the control device 200 appropriately adjusts the magnetic forces that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

[0018] Meanwhile, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by control device 200 so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Motor 121 also incorporates a rotational speed sensor (not shown), such as a Hall element, resolver, or encoder, and the rotational speed of rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0019] Furthermore, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device 200 uses the detection signals of both this phase sensor and the rotational speed sensor to detect the position of the magnetic pole.

[0020] A plurality of fixed blades 123 (123a, 123b, 123c...) are arranged at small gaps from the rotating blades 102 (102a, 102b, 102c...). Each of the rotating blades 102 (102a, 102b, 102c...) is formed at an angle of a predetermined degree from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward through collision. The fixed blades 123 (123a, 123b, 123c...) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals as an ingredient.

[0021] Similarly, the fixed blades 123 are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rows of rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported by being inserted between a plurality of stacked rows of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0022] The fixed vane spacer 125 is a ring-shaped member made of a metal such as aluminum, iron, stainless steel, or copper, or an alloy containing any of these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed vane spacer 125 with a small gap between them. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transferred to the base portion 129 is sent to the exhaust port 133.

[0023] Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower portion of the stator spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing any of these metals, and has multiple spiral thread grooves 131a engraved on its inner circumferential surface. The spiral direction of the threaded grooves 131a corresponds to the direction in which exhaust gas molecules are transported toward the exhaust port 133 when they move in the rotational direction of the rotor 103. A cylindrical portion 102d hangs down from the lowest portion of the rotor 103, adjacent to the rotor blades 102 (102a, 102b, 102c, etc.). The outer circumferential surface of this cylindrical portion 102d is cylindrical and protrudes toward the inner circumferential surface of the threaded spacer 131, and is adjacent to the inner circumferential surface of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the thread groove 131a.

[0024] The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

[0025] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the action of the rotor 102 and the stator 123 draws exhaust gas from the chamber through the intake port 101. The rotational speed of the rotor 102 is typically 20,000 rpm to 90,000 rpm, and the peripheral speed at the tip of the rotor 102 reaches 200 m / s to 400 m / s. The exhaust gas drawn in through the intake port 101 passes between the rotor 102 and the stator 123 and is transported to the base 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, but this heat is transferred to the stator 123 side by radiation or conduction through gas molecules of the exhaust gas.

[0026] The stator spacers 125 are joined together at their outer peripheries and transmit to the outside heat received by the stator 123 from the rotor 102 and frictional heat generated when exhaust gas comes into contact with the stator 123.

[0027] In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is formed on the inner circumferential surface of the threaded spacer 131. However, there are also cases where the thread groove is formed on the outer circumferential surface of the cylindrical portion 102d, and a spacer having a cylindrical inner circumferential surface is disposed around the outer circumferential surface of the cylindrical portion 102d.

[0028] Depending on the application of the turbomolecular pump 100, the electrical equipment section may be surrounded by a stator column 122 to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section, which is composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., and the interior of this stator column 122 may be kept at a predetermined pressure by purge gas.

[0029] In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

[0030] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that have been individually adjusted and identified for the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit section 141 within its body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) near the center of a base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.

[0031] In the semiconductor manufacturing process, some process gases introduced into a chamber have the property of solidifying when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the inlet port 101 and highest at the outlet port 133. If the pressure of the process gas exceeds a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the inlet port 101 to the outlet port 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100.

[0032] For example, when SiCl4 is used as the process gas in an Al etching system, the low vacuum (760 [torr] to 10 -2The vapor pressure curve shows that at low pressures (approximately 20°C) and pressures of 100[torr], solid products (e.g., AlCl3) precipitate and adhere to and accumulate inside the turbomolecular pump 100. When process gas deposits accumulate inside the turbomolecular pump 100, these deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The aforementioned products tend to solidify and adhere to high-pressure areas near the exhaust port 133 and the threaded spacer 131.

[0033] Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled pipe 149 is wrapped around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled pipe 149 are controlled based on the signal from this temperature sensor to maintain the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System).

[0034] Next, a description will be given of the amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B in the turbomolecular pump 100. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0035] 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

[0036] At this time, the transistor 161 has a diode cathode terminal 161a connected to the positive electrode 171a and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a diode cathode terminal 162a connected to the current detection circuit 181 and an anode terminal 162b connected to the negative electrode 171b.

[0037] Meanwhile, current regeneration diode 165 has its cathode terminal 165a connected to one end of electromagnet winding 151 and its anode terminal 165b connected to negative electrode 171b. Similarly, current regeneration diode 166 has its cathode terminal 166a connected to positive electrode 171a and its anode terminal 166b connected to the other end of electromagnet winding 151 via current detection circuit 181. Current detection circuit 181 is configured, for example, with a Hall sensor type current sensor or an electrical resistance element.

[0038] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0039] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) not shown in the figure of the control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on / off.

[0040] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Based on the comparison result, the amplifier control circuit 191 determines the size of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period under PWM control. As a result, gate drive signals 191a and 191b having these pulse widths are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162.

[0041] It is necessary to control the position of rotor 103 at high speed and with strong force when, for example, the rotor 103 passes through a resonance point during acceleration of its rotational speed or when a disturbance occurs during constant-speed operation. For this reason, a high voltage of, for example, about 50 V is used as power supply 171 so that the current flowing through electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between positive electrode 171a and negative electrode 171b of power supply 171 to stabilize power supply 171.

[0042] In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0043] Furthermore, when one of the transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161 and 162 in this manner, high-frequency noise such as harmonics generated in the turbomolecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

[0044] That is, when the detected current value is smaller than the current command value, both transistors 161 and 162 are turned on for a time period corresponding to pulse width time Tp1 only once in a control cycle Ts (for example, 100 μs), as shown in Fig. 3. Therefore, during this period, the electromagnet current iL increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0045] On the other hand, if the detected current value is greater than the current command value, both transistors 161 and 162 are turned off for a time period corresponding to pulse width time Tp2 only once during the control cycle Ts, as shown in Fig. 4. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from the negative pole 171b to the positive pole 171a via diodes 165 and 166.

[0046] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0047] 1 (the side of the intake port 101) serves as an intake section connected to the target device, and the lower side (the side on which the exhaust port 133 is provided on the base portion 129 so as to protrude to the left in the figure) serves as an exhaust section connected to an auxiliary pump (a back pump for roughing) (not shown) or the like. The turbomolecular pump 100 can be used in an inverted, horizontal, or inclined position in addition to the vertical position shown in Figure 1.

[0048] In the turbomolecular pump 100, the aforementioned outer cylinder 127 and base portion 129 are combined to form a single case (hereinafter, both may be collectively referred to as the "main body casing"). The turbomolecular pump 100 is electrically (and structurally) connected to a box-shaped electrical equipment case (not shown), and the aforementioned control device 200 is incorporated into the electrical equipment case.

[0049] The internal configuration of the main body casing of the turbomolecular pump 100 (a combination of an outer cylinder 127 and a base portion 129) can be divided into a rotation mechanism portion that rotates the rotor shaft 113 and the like using the motor 121, and an exhaust mechanism portion that is rotationally driven by the rotation mechanism portion. The exhaust mechanism portion can be considered to be divided into a turbomolecular pump mechanism portion that is composed of the rotor blades 102, fixed blades 123, and the like, and a groove exhaust mechanism portion (described later) that is composed of the cylindrical portion 102d, a threaded spacer 131, and the like.

[0050] The aforementioned purge gas (protective gas) is used to protect the bearing parts and the rotor 102, etc., to prevent corrosion caused by the exhaust gas (process gas), and to cool the rotor 102. This purge gas can be supplied by a general method.

[0051] For example, although not shown, a purge gas flow path extending linearly in the radial direction is provided at a predetermined location (such as a position approximately 180 degrees away from the exhaust port 133) of the base portion 129. Then, purge gas is supplied to this purge gas flow path (more specifically, a purge port serving as a gas inlet) from the outside of the base portion 129 via a purge gas cylinder (such as an N2 gas cylinder), a flow rate regulator (a valve device), or the like.

[0052] The aforementioned protective bearings 120 are also called "touchdown (T / D) bearings" or "backup bearings." These protective bearings 120 prevent the position or attitude of the rotor shaft 113 from changing significantly, even in the unlikely event of a problem with the electrical system or atmospheric inrush, and prevent damage to the rotor blades 102 and their surrounding areas.

[0053] In each of the drawings (FIGS. 1, 5 to 10, 13, and 14) showing the structure of the turbomolecular pump 100, hatching indicating cross sections of components has been omitted to avoid cluttering the drawings.

[0054] Next, we will explain the stress dispersion function and the like of the above-mentioned rotating body 103. As mentioned above, rotor shaft 113 is attached to the center of rotating body 103. As shown enlarged in Fig. 5, rotating body 103 has disk portion 212 with fitting hole 211 in the center, and fitting shaft portion 241 of rotor shaft 113 is fitted into fitting hole 211.

[0055] A relatively small-diameter protruding end portion 242 and the above-described fitting shaft portion 241 are formed at one axial end portion (here, the upper end portion in FIGS. 1 and 5) of rotor shaft 113. Protruding end portion 242 and fitting shaft portion 241 are formed with different diameters, and the diameter of fitting shaft portion 241 is larger than the diameter of protruding end portion 242.

[0056] Furthermore, the fitting shaft portion 241 and the protruding end portion 242 form a stepped shape. The fitting shaft portion 241 is coaxially inserted into the fitting hole 211 of the rotor 103 and contacts the inner circumferential surface of the fitting hole 211 while generating pressure using a predetermined method (here, annealing). Although not clearly shown, the axial length of the fitting shaft portion 241 that acts as the fitting portion is approximately equal to the thickness H of the disk portion 212 shown in FIG. 5. The protruding end portion 242 of the rotor shaft 113 is located outside the disk portion 212 of the rotor 103.

[0057] A plurality of (for example, six or eight) bolt through holes 213 are formed in the disk portion 212 of the rotor 103 and arranged around the fitting hole 211. Bolts 214 (fastening means), such as hexagon socket head bolts, are inserted into these bolt through holes 213. These bolts 214 are screwed into the rotor shaft 113. The rotor 103 and the rotor shaft 113 are connected to each other by the fastening force of the bolts 214.

[0058] Hereinafter, as shown in FIG. 6 , the fitting hole 211 and the area surrounding the fitting hole 211 in the disk portion 212 of the rotating body 103 are referred to as a fitting hole portion 215 (a stress reduction target portion). Furthermore, the bolt through hole 213 and the area surrounding the bolt through hole 213 in the disk portion 212 are referred to as a through hole portion 216 (also a stress reduction target portion). Furthermore, when the fitting hole portion 215 and the through hole portion 216 are adjacent to each other, an overlapping area may occur between the fitting hole portion 215, which is a stress reduction target portion, and the through hole portion 216, which is a stress reduction target portion. In this case, the overlapping area is also referred to as a stress reduction target portion. Here, in the present embodiment, the fitting hole portion 215 includes the fitting hole 211, and the through hole portion 216 includes the bolt through hole 213. However, the present invention is not limited to this. It is also possible for the fitting hole portion 215 not to include the fitting hole 211, and for the through hole portion 216 not to include the bolt through hole 213.

[0059] Furthermore, a disk-shaped annular washer 220 is sandwiched between the disk portion 212 and the head of the bolt 214. Furthermore, as shown in Fig. 6, a groove portion (inner groove portion of the recessed portion) 223a facing the plate surface of the washer 220 is formed on the outer periphery of the bottom of the recessed portion 223 of the disk portion 212 in which the washer 220 is disposed. Although not shown, the washer 220 has a plurality of through holes formed therein that can prevent gas from accumulating between the disk portion 212 and the washer.

[0060] 5, a rotor blade forming portion 217 (cylindrical portion) is formed integrally and continuously on the outer periphery of the disk portion 212 of the rotor 103. This rotor blade forming portion 217 is also formed integrally and continuously with the aforementioned cylindrical portion 102d of the rotor 103. Furthermore, a groove portion 218 is formed in a boundary portion 224 of the disk portion 212 with the rotor blade forming portion 217.

[0061] The groove 218 is formed on the inner circumferential surface 219 of the disk portion 212 and opens to the inner circumferential surface 219. Furthermore, in this embodiment, the groove 218 extends around the entire circumference of the inner circumferential surface 219 and has a constant cross-sectional shape around the entire circumference. Note that the invention according to this embodiment is not limited to forming the groove 218 around the entire circumference of the inner circumferential surface 219, and the groove 218 may be formed so as to be arranged intermittently along the circumferential direction of the inner circumferential surface 219.

[0062] 7, groove 218 has an inclined portion 221 and a curved portion 222. Of these, inclined portion 221 is inclined so as to become deeper from the center side of rotor 103 toward the outer periphery, and curved portion 222 is curved in an arc shape so as to become shallower from the center side of rotor 103 toward the outer periphery. Furthermore, inclined portion 221 is located toward the center of rotor 103, and curved portion 222 is located on the outer periphery side of inclined portion 221.

[0063] The inclined portion 221 is formed in a region adjacent to the inner circumferential surface 219 of the disk portion 212, and is continuous from the inner circumferential surface 219 at an inclination angle α1 with respect to the inner circumferential surface 219. The inclination angle α1 is substantially constant from the inner circumferential side to the outer circumferential side of the inclined portion 221. However, this is not limiting, and the inclination angle of the inclined portion 221 may change midway from the inner circumferential side to the outer circumferential side.

[0064] The curved portion 222 is formed so that the tangent angle is α2 with respect to the inner circumferential surface 219 of the disk portion 212. In FIG. 7, the tangent angle α2 is the angle of the tangent at the position where the curved portion 222 intersects with an extension line 219a of the inner circumferential surface 219. Furthermore, there is a relationship of α1<α2 between the inclination angle α2 and the tangent angle α2. In other words, with regard to the relationship between the tangent angle α2 and the inclination angle α1 in the groove portion 218, the inclination angle α1 is more gradual than the tangent angle α2, and the tangent angle α2 is larger than the inclination angle α1 and therefore more steeply inclined. Furthermore, it is desirable that the inclination angle α1 has an acute angle structure (α<45 degrees).

[0065] In a turbomolecular pump 100 having such a rotor 103, the pumping performance improves as the rotation speed of the rotor 103 increases. However, when designing the rotor 103, it is necessary to determine the shape and dimensions of each part so that excessive stress is not generated by centrifugal force during rotation.

[0066] Furthermore, a location where stress concentration is likely to occur in the rotating body 103 is the joint portion between the rotating body 103 and the rotor shaft 113. Examples of the joint portion between the rotating body 103 and the rotor shaft 113 include the through-hole portion 216 around the bolt through-hole 213 and the fitting hole portion 215 around the fitting hole 211.

[0067] Reducing the stress generated in these locations and preventing excessive increases in stress generated in other locations will improve the strength of the rotor 103 and the reliability of the turbomolecular pump 100. Furthermore, since it becomes possible to increase the room for stress generation, it becomes possible to increase the rotation speed of the rotor 103, and the exhaust performance of the turbomolecular pump 100 can be improved.

[0068] From this perspective, the inventors conducted extensive research into reducing stress in the through-holes 216 and the fitting holes 215, and came up with the idea of intentionally adding uneven portions to the disk portion 212 of the rotor 103 to increase the stress generated in the disk portion 212. Then, by forming the grooves 218 as described above as uneven portions, it becomes possible to increase the stress generated in the areas near the through-holes 216 and the fitting holes 215. As a result, it becomes possible to distribute stress in the rotor 103 (particularly the disk portion 212) and reduce stress in the through-holes 216 and the fitting holes 215, thereby improving the reliability and performance of the turbomolecular pump 100.

[0069] Furthermore, the inventors conducted simulations of a structural model in which grooves 218 were formed in rotor 103, and experiments using the actual object, and found that the stress generated in through-hole 216 and fitting hole 215 actually decreased. This can be considered to be because grooves 218 act as so-called "relief" of stress, averaging out the stress.

[0070] Even if the stress generated in the through-hole portion 216 and the fitting hole portion 215 can be reduced as described above, it is undesirable for the stress in the groove portion 218 to become excessive. Furthermore, it is undesirable for the provision of the groove portion 218 to result in excessive man-hours and costs for processing the rotor 103. For this reason, the inventors have considered the optimal shape and processing method for the groove portion 218, and have concluded that a shape in which the gently sloping portion 221 is located on the inner periphery and a relatively steep portion (here, the curved portion 222) is located on the outer periphery, as described above, is preferable. By forming the groove portion 218 of this shape in the rotor 103, it is possible to more evenly distribute the stress.

[0071] Fig. 9(a) shows a model of the deformation of the rotor 103 during rotation when no groove 218 is provided (conventional structure). Fig. 9(b) shows a similar model of the deformation of the rotor 103 during rotation when groove 218 is provided. When the rotor 103 rotates, centrifugal force acts on the rotor 103, and a load F acts on the rotor blade forming portion 217 toward the outer periphery. Furthermore, a moment due to the load F acts on the joint between the rotor 103 and the rotor shaft.

[0072] The rotating body 103 deforms with the fastening portion with the rotor shaft 113 (considered here as the through-hole portion 216) as a fulcrum, and the further away from the fulcrum toward the outer periphery, the greater the deflection and displacement toward the intake side (upper side in FIGS. 9(a) and 9(b)). In FIGS. 9(a) and 9(b), the amounts of axial displacement on the outer periphery side of the disk portion 212 are denoted by δa and δb, respectively, and the amounts of radial displacement on the exhaust side (lower side in FIGS. 9(a) and 9(b)) of the rotor blade forming portion 217 are denoted by γa and γb.

[0073] When the groove 218 is provided as shown in FIG. 9(b), with respect to the displacements δa and δb of the disk portion 212, δb is smaller than δa for reasons described below. Furthermore, with respect to the displacements γa and γb of the rotor-forming portion 217, the lower side of which is not constrained, γb is larger than γa. In other words, in the case of FIG. 9(b) where the groove 218 is provided, stress generated near the groove 218 is higher than in the case of FIG. 9(a) where the groove 218 is not provided, and deformation of the rotor-forming portion 217, which is located on the outer periphery of the groove 218, is greater. Stress corresponding to the increased deformation is generated in and around the groove 218, and the stress due to the load F is distributed not only to the fastening portion (fulcrum) but also to the groove 218.

[0074] Moreover, by dispersing the stress due to the load F to the groove 218, it is possible to reduce the stress generated at the fastening portion (fulcrum). Furthermore, by keeping the stress generated in the groove 218 at an appropriate level and preventing the stress generated in the groove 218 from increasing excessively, the strength of the rotor 103 and the reliability of the turbomolecular pump 100 are improved overall. Furthermore, since it is possible to increase the room for stress generation, it is possible to increase the rotation speed of the rotor 103, and it becomes possible to improve the exhaust performance of the turbomolecular pump 100.

[0075] Next, when manufacturing the groove portion 218 as described above, the work can be performed as shown in Fig. 10. For example, while the base material 230 of the rotating body 103 is rotated around its axis, a cutting tool (bite) 231 is advanced into the inner peripheral side of the base material 230. Here, the reference symbol C in Fig. 10 indicates the axis of the base material 230, and when manufacturing the groove portion 218, the base material 230 rotates around this axis C. Also, Fig. 10 shows only a portion of half of the base material 230, with the axis C as the boundary.

[0076] A turning tip (cutting edge) 232 is attached to the tip of cutting tool 231. Cutting edge surfaces 234a and 234b are formed on either side of corner 233 at the tip of tip 232. Tip 232 is attached to cutting tool 231 with the tip side facing the outer periphery (outside in the radial direction) of disk portion 212 of base material 230.

[0077] The cutting tool 231 moves back and forth along the axis C of the base material 230 and moves vertically and horizontally in a plane perpendicular to the axis C via a feed mechanism (not shown). The tip 232 comes into contact with the base material 230 with one cutting edge surface 234a facing obliquely toward the inner periphery (inward in the radial direction), and gradually cuts the rotating base material 230 while moving back and forth and vertically and horizontally as needed. The cutting tool 231 is guided so that the tip 232 cuts deeper into the base material 230 as it moves toward the outer periphery, forming the inclined portion 221.

[0078] Furthermore, the cutting tool 231 is retracted relative to the disk portion 212 while being moved toward the outer periphery. Then, the tip 232 moves from the disk portion 212 to reach the side of the rotor forming portion 217, and the curved portion 222 is formed. Such movement of the cutting tool 231 is performed within a narrower radial width than when forming the inclined portion 221. As a result, as shown in FIG. 7 , the radial width W1 of the inclined portion 221 (the width of the annular portion) is greater than the radial width W2 of the curved portion 222 (the width of the annular portion).

[0079] In this way, by making the inclination angle α1 of the inclined portion 221 smaller than the tangent angle α2 of the curved portion 222, the groove portion 218 can be formed as smoothly as possible. Also, in the outer peripheral portion of the disk portion 212, the base material 230 can be processed by disposing the cutting tool 231 closer to the inner peripheral side, which is the side where the rotor forming portion 217 is not present.

[0080] Then, when manufacturing the groove portion 218, the space (internal space) on the inner peripheral surface side of the base material 230 can be effectively utilized. Furthermore, the tip 232 can be processed so as not to interfere with the rotor forming portion 217. As a result, when manufacturing the groove portion 218, work such as changing the orientation of the cutting tool 231 is not required, and the groove portion 218 can be easily manufactured with a small number of steps. Furthermore, the groove portion 218 can be manufactured using a general cutting tool 231 without preparing a dedicated tool.

[0081] Next, the stress control function exerted between the rotating body 103 and the rotor shaft 113 will be described. Fig. 11 shows an enlarged view of the area surrounded by the dashed-dotted circle D in Fig. 1. Here, Fig. 11 does not show the longitudinal section of the fitting shaft portion 241 of the rotor shaft 113, but shows the longitudinal section of the portion below the fitting shaft portion 241 in the figure.

[0082] 11, a stress control recess 251 (spot facing portion) is formed in the base portion of the fitting shaft portion 241 of the rotor shaft 113. This stress control recess 251 is formed to a certain depth (for example, about 0.1 to 0.5 mm) by spot facing the opening of the female thread portion 252, into which the bolt 214 is screwed, around the base portion of the fitting shaft portion 241. Furthermore, the stress control recess 251 is formed so as to face the periphery of the opening of the bolt through hole 213 in the rotating body 103.

[0083] If a protrusion (not shown) exists on the opposing surfaces of the rotor 103 and the rotor shaft 113, the stress control recess 251 accommodates the protrusion in its internal space so that the opposing surfaces do not come into contact with (abut against) or compress the protrusion. The stress control recess 251 prevents an increase in stress generated in the disk portion 212 due to the application of stress generated on the protrusion or on the contact surface with the protrusion.

[0084] As a result, it is possible to prevent the relationship between the stress generated in the fitting hole 215 or the through-hole 216 and the stress generated in the groove 218 from being disrupted by pressure from the convex portion. The stress dispersion function of the groove 218 is therefore exerted as designed without being affected by pressure from the convex portion. Furthermore, by providing the stress control recess 251, it is possible to ensure that the stress dispersion function of the groove 218 functions more reliably.

[0085] Here, examples of convex portions include those (so-called plating drips) that occur when surface treatment (such as electroless nickel plating) is performed on the inner circumferential surfaces of the fitting hole 211 and the bolt through hole 213 to improve resistance to corrosive gases, and convex portions that unexpectedly occur in the fitting hole portion 215 and the through hole portion 216. Even if such convex portions occur in areas near the fitting hole 211 and the bolt through hole 213, the stress control recess 251 can prevent or suppress the generation of stress, thereby allowing the groove portion 218 to maximize its function.

[0086] While Fig. 11 shows an example in which the stress control recess 251 is provided on the rotor shaft 113, the present invention is not limited to this. For example, as shown in Fig. 12, a stress control recess 254 (counterbore portion) can be provided on the rotating body 103 side. In the example of Fig. 12, a counterbore is applied to the opening of the bolt through hole 213, thereby forming a certain depth (for example, about 0.1 to 0.2 mm). Even when the stress control recess 254 is formed on the rotating body 103 side in this way, it is possible to achieve the same effects of the invention as in the example of Fig. 11.

[0087] It is conceivable to select a part on the side where no protrusions are formed (or the side where protrusions are less likely to form) as the part on which to form the stress control recesses 251, 254. For example, of the rotating body 103 and the rotor shaft 113, it is conceivable to form the stress control recesses 251 on the rotor shaft 113, since plating is rarely applied to the rotor shaft 113.

[0088] According to the turbomolecular pump 100 of this embodiment as described above, the grooves 218 provided in the rotor 103 can disperse stress in the through-holes 216 and the fitting holes 215 when the rotor 103 rotates. This increases the stress that can be generated in the through-holes 216 and the fitting holes 215, and as a result, it becomes possible to improve the reliability and performance of the rotor 103 and the turbomolecular pump 100.

[0089] The averaging of stress by groove portion 218 does not result in a change in the overall energy related to stress generated in through-hole portion 216, fitting hole portion 215, and rotating body 103. However, it is possible to reduce stress in areas where stress exceeding the average may occur if groove portion 218 is not provided.

[0090] Further, groove portion 218 has an inclined portion 221 with an inclination angle α1 and a curved portion 222 with a tangent angle α2, and the inclination angle α1 and the tangent angle α2 have a relationship of α1<α2. It can be said that inclined portion 221 is gentler than curved portion 222, and curved portion 222 is steeper than inclined portion 221. Therefore, the gentle inclined portion 221 and the steep curved portion 222 can appropriately distribute stress to through hole portion 216 and fitting hole portion 215.

[0091] It is also possible to set both the inclination angle α1 and the tangent angle α2 to similarly gentle angles, in which case a similar stress distribution can be generated in both the inclined portion 221 and the curved portion 222. On the other hand, as described above, by making the curved portion 222 have a structure that is steeper than the inclined portion 221, it is possible to reduce the radial width W2 of the curved portion 222 (the width of the annular portion).

[0092] 7, the inclined portion 221 is formed on the inner peripheral side far from the rotor forming portion 217, and the curved portion 222 is formed on the outer peripheral side close to the rotor forming portion 217. Therefore, when machining the inclined portion 221, the internal space of the base material 230 is effectively utilized, and the groove portion 218 can be machined while preventing the base end side of the tip 232 of the cutting tool 231 from interfering with the rotor forming portion 217. This makes it possible to machine the groove portion 218 at low cost.

[0093] 7, the cross-sectional shape of groove 218 is formed by combining inclined portion 221 and curved portion 222. However, this is not limiting. For example, as shown in FIG. 8, groove 228 may be formed by combining first inclined portion 226 and second inclined portion 227. In the example of FIG. 8, first inclined portion 226 is formed similarly to inclined portion 221 in the example of FIG. 7, but second inclined portion 227 is not formed by an arc-shaped surface but by a substantially flat inclined surface with an inclination angle of α3. In addition, in the example of FIG. 8, first inclined portion 226 and second inclined portion 227 are continuous via connecting curved surface portion 229, which has an arc-shaped cross-sectional shape.

[0094] 8, it can be said that the first inclined portion 226 on the inner circumferential side is gentler than the second inclined portion 227 on the outer circumferential side, and the second inclined portion 227 is steeper than the first inclined portion 226. It is therefore possible to process the groove portion 228 while effectively utilizing the internal space of the base material 230.

[0095] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified in various ways. For example, the arrangement of the groove portion 218 is not limited to the boundary portion 224 between the disk portion 212 and the rotor blade forming portion 217 as shown in Fig. 5, but may be any portion closer to the inner periphery than the boundary portion 224 (a portion closer to the outer periphery than the fitting hole portion 215 or the through-hole portion 216 and closer to the inner periphery than the boundary portion 224). Furthermore, it is also possible to provide a plurality of groove portions 218 between the boundary portion 224 and the fitting hole 211.

[0096] Furthermore, the grooves 218 can be provided on at least one of the inner circumferential surface and the outer circumferential surface of the rotor 103. The grooves 218 can also be arranged so as to open onto the outer circumferential surface of the rotor 103. An example of the outer circumferential surface of the rotor 103 is the outer circumferential surface 225 of the disk portion 212. Another example of the inner circumferential surface or the outer circumferential surface of the rotor can be the inner circumferential surface or the outer circumferential surface of the cylindrical portion 102d (FIG. 1) of the rotor 103 that is closer to the exhaust side than the rotor blades 102. Furthermore, the inner circumferential surface and the outer circumferential surface of the rotor 103 can be distinguished, for example, by defining the surface facing the internal space of the rotor 103 as the inner circumferential surface and the other surface as the outer circumferential surface.

[0097] Here, it is considered that the stress dispersion function of groove portion 218 is more easily exhibited when groove portion 218 is disposed on the outer periphery side of, and in proximity to, the joining portions (fitting hole portion 215 and through-hole portion 216) between rotating body 103 and rotor shaft 113. In the example of Fig. 5, examples of such portions include portions on the outer periphery side of through-hole portion 216 on inner circumferential surface 219 or outer circumferential surface 225 of disk portion 212.

[0098] It is also possible to provide grooves 218 on both inner circumferential surface 219 and outer circumferential surface 225 of disk portion 212. According to the analysis by the inventors, stress generated in fitting hole 215 and through-hole 216 is smaller when grooves 218 are provided on inner circumferential surface 219 than when grooves 218 are provided on outer circumferential surface 225. Furthermore, when grooves 218 are provided on both inner circumferential surface 219 and outer circumferential surface 225 of disk portion 212 as described above, stress is averaged, and the effect of stress dispersion is further enhanced.

[0099] Furthermore, the inventors' analysis showed that even when the thickness H (FIG. 5) of disk portion 212 was thinned, the effect of stress dispersion due to the provision of groove 218 was significant. Furthermore, in the examples of FIGS. 1 and 5, groove 223a facing the plate surface of washer 220 is formed on the outer periphery of the bottom of recessed portion 223, and it can be considered that groove 223a also has a stress dispersion function.

[0100] Furthermore, in Figures 1 and 5, etc., the coupling relationship between the rotating body 103 and the rotor shaft 113 is illustrated as an example in which the rotor shaft 113 is inserted so as to pass through the mating hole 211 of the rotating body 103, but the present invention is not limited to this and can be applied to various types of rotating bodies 103b to 103g, for example, as shown in partial cross-section in Figures 13(b) to (g).

[0101] For example, FIG. 13(a) shows an enlarged, partially longitudinal cross-section view of a portion (disk portion 212) of the rotor 103 according to the embodiment shown in FIG. 5. However, the present invention is not limited to this example. As shown in FIG. 13(b), the present invention can also be applied to a rotor shaft 113b coupled to a rotor 103b of a type that does not have a fitting hole (reference numeral 211 in FIG. 5). The rotor shaft 113b shown in FIG. 13(b) does not have the fitting shaft portion 241 or the protruding end portion 242 shown in FIG. 13(a). In this structure in which the rotor shaft 113b is butted against the rotor 103b to fasten them together, the groove portion 218 is disposed on the fastening surface of the rotor 103b (the inner peripheral surface 219b against which the rotor shaft 113b butts) or on an extended surface thereof.

[0102] 13(c) shows a type of rotor 103c that does not have bolt holes around fitting hole 211c in disk portion 212c. This type of rotor 103c is joined to rotor shaft 113c by attaching nut 256 to protruding end 242c of rotor shaft 113c and tightening nut 256 to press washer 220 against rotor 103c.

[0103] Furthermore, Figure 13(d) shows a type of rotor 103d in which fitting hole 211d does not pass through disk portion 212d, but is closed at a location halfway through in the thickness direction of disk portion 212d. When this type of rotor 103d is used, rotor shaft 113d is fixed to rotor 103d by bolt 214 in a state in which it does not pass through disk portion 212d. Note that, in the rotor 103d and rotor shaft 113d shown in Figure 13(d), it can also be said that rotor shaft 113d is engaged with rotor 103d by inserting protrusion 257 formed on the axial end of rotor shaft 113d into a recess (reference numeral omitted) of rotor 103d.

[0104] 14(a) shows a rotating body 103e that is similar to the rotating body 103b of the type shown in FIG. 13(b), but differs in that it has an engagement structure with a washer 220e via a protrusion 258. In the example of FIG. 14(a), a protrusion 258 is formed on the washer 220e, and this protrusion 258 fits into a recess (reference numeral omitted) in the rotating body 103e. In this way, even in the structure in which the rotor shaft 113b is abutted against the rotating body 103b to fasten them together, the groove 218 is arranged on the fastening surface of the rotating body 103e (the inner circumferential surface 219e against which the rotor shaft 113e abuts) or on an extended surface thereof, as in the example of FIG. 13(b).

[0105] Also, what is shown in FIG. 14(b) is a rotor 103f of a type that has a protrusion 259, and this protrusion 259 is inserted into a recess (reference numeral omitted) of the rotor shaft 113f to engage with the rotor shaft 113f.

[0106] Furthermore, Figure 14(c) shows a type of rotating body 103g having a protrusion 260 and a convex portion 259, in which the protrusion 260 is inserted into a recess in the washer 220g and the convex portion 259 is inserted into a recess (symbol omitted) in the rotor shaft 113g, similar to the example in Figure 14(b).

[0107] Even in turbomolecular pumps equipped with these various types of rotors 103b to 103g and rotor shafts 113b to 113g, by providing grooves 218 and 223a at appropriate positions, it is possible to achieve stress dispersion function similar to the turbomolecular pump 100 shown in Figures 1 and 5, etc.

[0108] The present invention is not limited to the above-described embodiments, and many modifications can be made by those skilled in the art using their ordinary creative abilities within the scope of the technical concept of the present invention. [Explanation of symbols]

[0109] 100 Turbomolecular pump (vacuum pump) 102 Rotor 103 Rotating body (rotating body for vacuum pump) 113 Rotor shaft (rotating shaft) 214 Bolts (fastening means) 215 Fitting hole (stress reduction target area) 216 Through-hole section (stress reduction target section) 217 Rotor forming section 218 Groove 219 Inner surface of the disk part (inner surface) 219b Fastening surface (and extension surface) of rotating body 225 Outer surface of the disk part (outer surface) 251, 254 Stress control recess (counterbore)

Claims

1. The cylindrical portion has rotors on its outer periphery.

1. A vacuum pump having a rotor fastened to a rotary shaft by a fastening means and rotatable together with the rotary shaft, At least one of a fitting hole portion of the rotating body that fits with the rotating shaft and a through-hole portion through which the fastening means passes is a stress reduction target portion, and the rotating body is provided with a groove portion that reduces stress generated in the stress reduction target portion during rotation of the rotating body, the rotating body includes a disk portion into which the fitting shaft portion of the rotating shaft is fitted, and a recessed portion whose bottom is formed by the disk portion, a first groove formed in a circumferential direction on the underside of the disk portion, the underside being the surface opposite the bottom portion; and a second groove formed in a circumferential direction on the outer periphery of the bottom portion of the recessed portion.

2. 2. The vacuum pump according to claim 1, wherein the groove is provided on an outer circumferential side of the fitting hole or the through hole.

3. 3. The vacuum pump according to claim 1, wherein the first groove portion has a gently inclined structure at least on the inner circumferential side.

4. 4. The vacuum pump according to claim 1, wherein the first groove portion is disposed on a fastening surface of the rotor or on an extension thereof.

5. The rotating body is subjected to a surface treatment, 5. The vacuum pump according to claim 1, wherein a counterbore portion is provided on the periphery of at least one of the fitting hole portion and the through hole portion to avoid contact with the rotary shaft.

6. The cylindrical portion has rotors on its outer periphery. A vacuum pump rotor fastened to a rotary shaft by fastening means, At least one of a fitting hole portion that fits with the rotating shaft and a fastening portion to which the fastening means is fastened is a stress reduction target portion, and the fitting hole portion is provided with a groove portion that reduces stress generated in the stress reduction target portion during rotation, the vacuum pump rotor includes a disk portion into which a fitting shaft portion of the rotary shaft is fitted, and a recessed portion whose bottom is formed by the disk portion, a first groove formed in a circumferential direction on the underside of the disk portion, the underside being the surface opposite the bottom portion; and a second groove formed in a circumferential direction on the outer periphery of the bottom portion of the recessed portion.

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