Vacuum pump and hermetic connector

Abstract

[Problem] To achieve a hermetic connector with a small size and high performance while suppressing manufacturing cost thereof. [Solution] Provided is a vacuum pump (100) provided with a hermetic connector (10), the vacuum pump (100) being characterized in that: the hermetic connector (10) has pins (11, 12) that are electrically connected, a connector base part (13) that surrounds the pins (11, 12), and a sealing part (14) that seals between the pins (11, 12) and the connector base part (13); and the sealing part (14) is formed of an insulating resin material.

Description

Vacuum pump and hermetic connector

[0001] The present invention relates to a vacuum pump and a hermetic connector for use in the vacuum pump.

[0002] As a conventional technique in this technical field, for example, a vacuum pump described in Patent Document 1 is equipped with a hermetic connector having a horizontal structure. The hermetic connector used in the vacuum pump is required to have high airtightness and high heat resistance. For this reason, the gap between the connector base and the pin of the hermetic connector is generally sealed with a glass material.

[0003] Patent No. 6912196

[0004] When manufacturing the above-mentioned conventional hermetic connectors, the process of sealing with glass material is special, which poses a problem of high manufacturing costs. Furthermore, hermetic connectors used in vacuum pumps are required to be compact, but they require a large number of pins and a high level of leak rate performance. In particular, in the case of vacuum pumps, if air enters the interior through the hermetic connector, there is a risk of a decrease in pump performance. Therefore, there is a demand for inexpensive production of small, high-performance hermetic connectors with a specified leak rate performance.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to achieve a small, high-performance hermetic connector while reducing the manufacturing cost.

[0006] In order to achieve the above object, a first aspect of the present invention is a vacuum pump equipped with a hermetic connector, wherein the hermetic connector has electrically connected pins, a connector base portion surrounding the pins, and a sealing portion sealing between the pins and the connector base portion, and the sealing portion is made of an insulating resin material.

[0007] In the above configuration, the sealing portion includes a first sealing portion that covers the outer surface of the pin and a second sealing portion that seals between the first sealing portion and the connector base portion, and the connector base portion is made of a metal material, the first sealing portion is made of a first resin material, and the second sealing portion is made of a second resin material.

[0008] In the above configuration, the linear expansion coefficient of the first resin material is equal to or greater than the linear expansion coefficient of the second resin material.

[0009] In the above configuration, the hermetic connector further has a labyrinth structure between the pin and the sealing portion for preventing the passage of gas.

[0010] In the above configuration, the labyrinth structure includes a convex portion and / or a concave portion provided on the outer surface of the pin.

[0011] In order to achieve the above object, a second aspect of the present invention is a hermetic connector for use in a vacuum pump, comprising electrically connected pins, a connector base portion surrounding the pins, and a sealing portion sealing the space between the pins and the connector base portion, wherein the sealing portion is made of an insulating resin material.

[0012] According to the present invention, it is possible to realize a small, high-performance hermetic connector while suppressing the manufacturing cost. Note that problems, configurations, and effects other than those described above will become apparent from the following description of the embodiment.

[0013] 1 is a longitudinal sectional view of a turbomolecular pump according to an embodiment of the present invention; FIG. 2 is a circuit diagram of an amplifier circuit of the turbomolecular pump shown in FIG. 1; FIG. 3 is a time chart showing control of the amplifier control circuit when the current command value is greater than the detection value; FIG. 4 is a time chart showing control of the amplifier control circuit when the current command value is smaller than the detection value; (a) a front view of the hermetic connector according to an embodiment, (b) a Vb-Vb sectional view; (a) a front view of the hermetic connector according to Modification 1, (b) a VIb-VIb sectional view; (a) a longitudinal sectional view of the hermetic connector according to Modification 2, (b) an enlarged view of part A; (a) to (c) diagrams showing variations of the labyrinth structure;

[0014] Hereinafter, a vacuum pump according to the present invention will be described with reference to the drawings, taking a turbomolecular pump as an example.

[0015] 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, which is an exterior body. Inside the outer tube 127, a rotor 103 is provided. The rotor 103 has multiple turbine blades 102 (102a, 102b, 102c, ...) arranged radially and in multiple stages around its periphery for sucking in and exhausting gas. A rotor shaft 113 is attached to the center of the rotor 103. The 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 a metal such as aluminum, an aluminum alloy, or stainless steel.

[0016] 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 depending on 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.

[0017] 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.

[0018] The rotor shaft 113 is made of a material with high magnetic permeability (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. In addition, 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.

[0019] 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.

[0020] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for each of the axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of each of the axial electromagnets 106A and 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] A plurality of stator blades 123 (123a, 123b, 123c...) are arranged with a small gap between them and the rotor blades 102 (102a, 102b, 102c...). These multiple stages of rotor blades 102 and multiple stages of stator blades 123 form a turbo pump section. Each of the rotor 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 collisions. The stator 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.

[0025] 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 stages of the 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 fixed blade spacers 125 (125a, 125b, 125c, ...).

[0026] 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 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base 129 and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) and is transported toward the base 129 is sent to the exhaust port 133.

[0027] Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 functioning as a thread groove pump portion is disposed between the lower portion of the fixed vane 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 these metals, and has multiple spiral thread grooves 131a engraved on its inner circumferential surface. The spiral direction of the thread 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, following the rotor vanes 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 131 a by the rotor 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the thread groove 131 a.

[0028] The base 129 is a disk-shaped member that forms the base of the turbomolecular pump 100 and is generally made of a metal such as iron, aluminum, or stainless steel. The base 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. A hermetic connector 10 is provided on the side of the base 129. The control device 200 is connected via this hermetic connector 10. Details of the hermetic connector 10 will be described later.

[0029] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the rotor 102 and the stator 123 act to draw 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 in the exhaust gas.

[0030] 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 .

[0031] 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, conversely, there are also cases where a 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 it.

[0032] Depending on the application of the turbomolecular pump 100, the electrical equipment section may be covered 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.

[0033] 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. As shown in FIG. 1 , the stator column 122 is erected at the center of the base portion 129. In this embodiment, a water-cooled pipe 149 is provided in the base portion 129 as a cooling means. Cooling water is supplied to this water-cooled pipe 149, thereby maintaining the base portion 129 and the stator column 122 at an appropriate temperature.

[0034] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that are individually adjusted and specific to the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit unit 141 within its body. The electronic circuit unit 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor devices for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit unit 141 is housed below a rotational speed sensor (not shown) near the center of a base unit 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.

[0035] 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 101 and highest at the outlet 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 101 to the outlet 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100.

[0036] For example, when SiCl4 is used as the process gas in an Al etching apparatus, the vapor pressure curve shows that at low vacuum (760 torr to 10-2 torr) and low temperature (approximately 20°C), a solid product (e.g., AlCl3) precipitates and adheres to and accumulates inside the turbomolecular pump 100. As a result, when precipitates of the process gas 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 product is prone to solidification and adhesion in high-pressure areas near the exhaust port 133 and the threaded spacer 131.

[0037] Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled pipe 149 is wound around the outer periphery of the base portion 129 or the like, and a temperature sensor (not shown, for example, a thermistor) is embedded in the base portion 129, and heating by the heater and cooling by the water-cooled pipe 149 are controlled based on a signal from this temperature sensor so as to maintain the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; TMS; Temperature Management System).

[0038] Next, an 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 will be described. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0039] 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to the positive electrode 171a of the power supply 171 via a transistor 161, and the other end is connected to the 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.

[0040] 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.

[0041] Meanwhile, the current regenerating diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative electrode 171b. Similarly, the current regenerating diode 166 has its cathode terminal 166a connected to the positive electrode 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detecting circuit 181. The current detecting circuit 181 is configured, for example, by a Hall sensor type current sensor or an electrical resistance element.

[0042] The amplifier circuit 150 configured as described 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.

[0043] 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.

[0044] 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 magnitude of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period of 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.

[0045] It is necessary to control the position of the 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 voltage of, for example, about 50 V is used as the power supply 171 so that a rapid increase (or decrease) in the current flowing through the electromagnet winding 151 can be achieved. In addition, a capacitor (not shown) is usually connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 to stabilize the power supply 171.

[0046] In this configuration, when both the 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.

[0047] 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.

[0048] 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 a pulse width time Tp1 only once during a control cycle Ts (e.g., 100 μs), as shown in Fig. 3. Therefore, the electromagnet current iL during this period 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.

[0049] 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 electrode 171b to the positive electrode 171a via diodes 165 and 166.

[0050] 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.

[0051] <Hermetic Connector Structure> Next, a detailed description will be given of the structure of the hermetic connector 10 used in the turbo molecular pump 100. Fig. 5(a) is a front view of the hermetic connector 10. Fig. 5(b) is a cross-sectional view taken along line Vb-Vb of Fig. 5(a).

[0052] As shown in Figures 5(a) and (b), the hermetic connector 10 of this embodiment has a plurality of electrically connected small-diameter pins 11 and large-diameter pins 12, a connector base portion 13 in the shape of a horizontally long rectangular frame that surrounds the plurality of pins 11 and 12, and a sealing portion 14 that seals between the plurality of pins 11 and 12 and the connector base portion 13.

[0053] In this embodiment, the small diameter pin 11 and the large diameter pin 12 are each formed in a thin and long cylindrical shape, but the shape is not limited thereto. For example, the pins 11 and 12 may be formed in a cylindrical shape with a step formed by arranging cylinders of different diameters coaxially and integrating them, or may be formed in a rectangular column shape instead of a cylindrical shape.

[0054] The connector base 13 is made of a metal material such as stainless steel. The connector base 13 has a horizontally long opening 13a in the center and holes 18 at the four corners for bolting to the base 129 of the turbomolecular pump 100. The aspect ratio of the connector base 13 is, for example, approximately 1:1.5 to 1:2. Although the connector base 13 is formed in a plate shape, the shape is not critical. Any shape of connector base can be used.

[0055] The sealing portion 14 is made of an insulating resin material. Examples of resin materials that can be used include polyamide / nylon (PA), polyphenylene ether (PPE), polyphenylene sulfide (PPS), and polybutylene terephthalate (PBT). As shown by the diagonal lines in FIG. 5A, the sealing portion 14 is filled between the connector base portion 13 and the pins 11 and 12, and the connector base portion 13 and the pins 11 and 12 are integrally molded via the sealing portion 14. For example, the pins 11 and 12 may be insert-molded into the sealing portion 14.

[0056] Next, the effects of this embodiment configured as above will be described.

[0057] Because the sealing portion 14 is made of an insulating resin material, the manufacturing process is simpler than with conventional structures that use glass material, thereby reducing the manufacturing costs of the hermetic connector 10. Furthermore, the hermetic connector 10 used in the turbomolecular pump 100 requires many wirings for the power lines of the motor and electromagnet, sensors, etc., which necessitates a large number of pins 11 and 12, and a high level of leak rate performance (sealing performance).In this embodiment, however, the connector base portion 13 and the pins 11 and 12 are integrally molded with the sealing portion 14 made of a resin material, thereby achieving a high level of leak rate performance.

[0058] Furthermore, because the connector base portion 13 is made of a metal material, an O-ring can reliably seal the gap between the connector base portion 13 and the base portion 129 of the turbomolecular pump 100. Therefore, the hermetic connector 10 according to this embodiment is suitable for the turbomolecular pump 100. Furthermore, because the connector base portion 13 has a horizontally elongated configuration, the axial (height) dimensions of the turbomolecular pump 100 can be made compact.

[0059] As described above, according to this embodiment, it is possible to realize a small, high-precision, and high-quality hermetic connector 10 with a low leak rate at low cost. Furthermore, by incorporating the high-performance hermetic connector 10 into the turbomolecular pump 100, it is possible to prevent a decrease in the exhaust performance of the turbomolecular pump 100.

[0060] (Modification 1) Next, a description will be given of the structure of the hermetic connector 20 according to Modification 1. Fig. 6(a) is a front view of the hermetic connector 20. Fig. 6(b) is a cross-sectional view taken along line VIb-VIb in Fig. 6(a).

[0061] As shown in Figures 6(a) and (b), the hermetic connector 20 of variant example 1 has a plurality of electrically connected small-diameter pins 21 and large-diameter pins 22, a round frame-shaped connector base portion 23 that surrounds the plurality of pins 21, 22, and a first sealing portion 25 and a second sealing portion 26 that seal between the plurality of pins 21, 22 and the connector base portion 23.

[0062] The connector base portion 23 is made of a metal material such as stainless steel, and has a circular opening 23a in the center and holes 28 at the four corners for bolting to the base portion 129 of the turbomolecular pump 100.

[0063] The first sealing portion 25 covers the outer surfaces (outer peripheral surfaces) of the pins 21 and 22. The first sealing portion 25 is formed of a cylindrical body that closely fits the outer shapes of the pins 21 and 22. The second sealing portion 26 seals the gap between the first sealing portion 25 and the connector base portion 23. In other words, the second sealing portion 26 seals the gap between the multiple pins 21 and 22 covered by the first sealing portion 25 and the connector base portion 23.

[0064] Both the first sealing portion 25 and the second sealing portion 26 are made of an insulating resin material, such as polyamide / nylon (PA), polyphenylene ether (PPE), polyphenylene sulfide (PPS), or polybutylene terephthalate (PBT). However, the linear expansion coefficient α1 of the resin material of the first sealing portion 25 (the first resin material) is equal to or greater than the linear expansion coefficient α2 of the resin material of the second sealing portion 26 (the second resin material) (α1≧α2).

[0065] The hermetic connector 20 according to the first modification achieves the same effects as the hermetic connector 10 according to the above embodiment. Furthermore, because the linear expansion coefficient α1 of the first sealing portion 25 is equal to or greater than the linear expansion coefficient α2 of the second sealing portion 26, hermeticity can be maintained even when a difference in thermal deformation occurs between the connector base portion 23 made of a metal material and the first sealing portion 25 and second sealing portion 26 made of a resin material. In particular, during operation of the turbomolecular pump 100, the ambient temperature around the hermetic connector 20 rises, causing a significant difference in thermal deformation between the connector base portion 23 and the first sealing portion 25 and second sealing portion 26. However, by using two types of resin materials with different linear expansion coefficients, the difference in thermal deformation can be reduced. Furthermore, because the linear expansion coefficients satisfy the relationship α1 ≧ α2, gaps can be prevented from occurring around the pins 21 and 22.

[0066] In Modification 1, the first sealing portion 25 and the second sealing portion 26 may be made of the same resin material. In this case, the first sealing portion 25 and the second sealing portion 26 replace the sealing portion 14 according to the above-described embodiment. In other words, the first sealing portion 25 and the second sealing portion 26 are manufactured as separate members, and are ultimately integrated together to function as the sealing portion 14. Even with this configuration, the same effects as those of the above-described embodiment can be achieved.

[0067] (Modification 2) Next, the structure of a hermetic connector 30 according to Modification 2 will be described. The hermetic connector 30 according to Modification 2 has the same basic configuration as the hermetic connector 10 shown in Figures 5(a) and 5(b), but differs in that it is provided with a labyrinth structure 31, which will be described below. Therefore, the same components of the hermetic connector 30 as those of the hermetic connector 10 will be assigned the same reference numerals and descriptions thereof will be omitted.

[0068] FIG. 7( a) is a longitudinal cross-sectional view of a hermetic connector 30 according to Modification 2. FIG. 7( b) is an enlarged view of portion A in FIG. 7( a). Note that the small-diameter pin 11 is not shown in FIG. 7( a). As shown in FIGS. 7( a) and 7( b), the hermetic connector 30 according to Modification 2 has a labyrinth structure 31. The labyrinth structure 31 is composed of a protrusion 32 provided on the large-diameter pin 12 and a recess 33 provided on the sealing portion 14. More specifically, the large-diameter pin 12 has a plurality of protrusions 35 protruding radially from its outer surface. The plurality of protrusions 35 are provided at intervals along the axial direction of the large-diameter pin 12. Each protrusion 35 is a disc-shaped flange protruding from the outer peripheral surface of the large-diameter pin 12.

[0069] On the other hand, the sealing portion 14 is made of a resin material filled between the connector base portion 13 and the large diameter pin 12, and therefore a recess 36 is formed that follows the shape of the protrusion 35. In the normal state, the protrusion 35 and the recess 36 are in close contact with each other, ensuring sealing. The small diameter pin 11 may also be provided with a labyrinth structure 31.

[0070] During operation of the turbomolecular pump 100, the ambient temperature of the hermetic connector 10 becomes high, which may cause a gap to form between the large diameter pin 12 and the sealing portion 14 due to differences in the linear expansion coefficient. However, in Modification 2, the large diameter pin 12 is provided with a labyrinth structure 31, which prevents air from passing through the gap between the large diameter pin 12 and the sealing portion 14. This prevents a decrease in the leak rate performance of the hermetic connector 10, and maintains good exhaust performance of the turbomolecular pump 100. The labyrinth structure also has the advantage of preventing the large diameter pin 12 from being pulled out.

[0071] Next, variations of the labyrinth structure will be described. Figures 8(a), (b), and (c) show variations of the labyrinth structure.

[0072] 8(a) has a convex portion 42 that is bent like a key. Therefore, a concave portion 43 formed in the sealing portion 14 also has a bent shape that follows the convex portion 42. Even with this configuration, it is possible to prevent air from passing through the gap between the large diameter pin 12 and the sealing portion 14.

[0073] 8(b) is composed of an uneven portion 52 formed on the surface of the large diameter pin 12 by knurling, sandblasting, or the like, and an uneven portion 53 formed to follow the uneven portion 52. Even with this configuration, it is possible to prevent air from passing through the gap between the large diameter pin 12 and the sealing portion 14.

[0074] 8(c) is composed of a recess 62 formed in the large diameter pin 12 and a protrusion 63 formed in the sealing portion 14 so as to conform to this recess 62. Even with this configuration, it is possible to prevent air from passing through the gap between the large diameter pin 12 and the sealing portion 14.

[0075] In this way, by providing a labyrinth structure between the large diameter pin 12 and the sealing portion 14, even if a gap occurs between the large diameter pin 12 and the sealing portion 14, it is possible to prevent gas from easily passing through this gap. In other words, any structure that makes it difficult for gas to pass through the gap between the large diameter pin 12 and the sealing portion 14 can be used as the labyrinth structure of the present invention.

[0076] 7 and 8 show an example of the sealing portion 14 made of a resin material, but the labyrinth structures 31, 41, 51, and 61 can also be used for sealing portions made of conventional glass materials. In other words, a labyrinth structure can be applied between the pin and the sealing portion of any hermetic connector. Furthermore, by providing a labyrinth structure, even if a gap occurs between the pin and the sealing portion, gas can be prevented from passing through the gap, preventing a decrease in the leak rate performance of the hermetic connector 10 and further preventing a decrease in the exhaust performance of the turbomolecular pump.

[0077] In the present invention, the gas that passes through the hermetic connector 10 is determined by the relationship between the internal pressure and the external pressure of the turbomolecular pump 100. If the internal pressure is higher than the external pressure, there is a possibility that exhaust gas present in the turbomolecular pump 100 will pass from the hermetic connector 10 to the outside. In this case, the gas that passes through the hermetic connector 10 is the exhaust gas present in the turbomolecular pump 100. If the internal pressure is lower than the external pressure, external gas (such as the atmosphere) will pass through the hermetic connector 10. Regardless of the relationship between the internal pressure and the external pressure, the labyrinth structures 31, 41, 51, and 61 of the hermetic connector 10 can prevent gas from passing through.

[0078] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various alternatives, modifications, variations, combinations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the appended claims.

[0079] For example, the shape of the connector base of the hermetic connector is not limited to the horizontally elongated rectangular frame or round frame described above. Any shape of the connector base can be used. Furthermore, the shape of the connector base may be a box shape instead of a frame shape.

[0080] 10, 20, 30 Hermetic connector 11, 21 Small diameter pin (pin) 12, 22 Large diameter pin (pin) 13, 23 Connector base portion 13a, 23a Opening 14 Sealing portion 18, 28 Hole 25 First sealing portion 26 Second sealing portion 31, 41, 51, 61 Labyrinth structure 32, 42, 62 Convex portion 33, 43, 63 Concave portion 52, 53 Concave and concave portion 100 Turbo molecular pump (vacuum pump)

Claims

1. A vacuum pump equipped with a hermetic connector, the hermetic connector having: electrically connected pins; a connector base portion surrounding the pins; and a sealing portion that seals between the pins and the connector base portion, the sealing portion being made of an insulating resin material.

2. A vacuum pump as claimed in claim 1, characterized in that the sealing portion includes a first sealing portion covering the outer surface of the pin, and a second sealing portion sealing between the first sealing portion and the connector base portion, the connector base portion being made of a metal material, the first sealing portion being made of a first resin material, and the second sealing portion being made of a second resin material.

3. A vacuum pump according to claim 2, characterized in that the linear expansion coefficient of the first resin material is equal to or greater than the linear expansion coefficient of the second resin material.

4. A vacuum pump as claimed in claim 1, characterized in that said hermetic connector further has a labyrinth structure between said pin and said sealing portion for preventing the passage of gas.

5. A vacuum pump as claimed in claim 4, characterized in that the labyrinth structure includes a protrusion and / or a recess provided on the outer surface of the pin.

6. A hermetic connector for use in a vacuum pump, comprising: electrically connected pins; a connector base portion surrounding the pins; and a sealing portion that seals between the pins and the connector base portion, the sealing portion being made of an insulating resin material.

Images