Foreign matter accumulation amount estimation device and pipe component

Abstract

To provide a foreign matter accumulation amount estimation device capable of estimating an accumulation amount of foreign matter.SOLUTION: This device is provided with a conductive casing 212 having an inlet 225A and an outlet 225B, a conductor member 214 arranged inside the casing 212 with a clearance (t) to the casing 212, a measuring instrument 216 for measuring electrostatic capacity between the casing 212 and the conductor member 214, and an arithmetic unit 218 for estimating a foreign matter deposit quantity in the casing 212 from a change in the electrostatic capacity. The conductor member 214 is provided with a communication port 236.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a foreign matter deposition amount estimation device and a piping component that can be used in, for example, a vacuum system. [Background technology]

[0002] Turbomolecular pumps are commonly known as a type of vacuum pump. These turbomolecular pumps are used, for example, for exhausting gases in manufacturing equipment for semiconductors, flat panels, and the like. In turbomolecular pumps, a motor inside the pump body is energized to rotate rotors, which eject gas molecules (gas molecules) from the gas (process gas) drawn into the pump body, thereby exhausting the gas. Some turbomolecular pumps are equipped with heaters and cooling tubes to properly manage the temperature inside the pump.

[0003] In vacuum pumps used to exhaust gas from semiconductor and flat panel manufacturing equipment, reaction products (foreign matter) produced during the semiconductor and flat panel manufacturing process can accumulate inside the vacuum pump or in the piping connected downstream of the vacuum pump. If a large amount of foreign matter accumulates, it can disrupt the gas flow inside the vacuum pump or collide with rotating parts, causing problems. For this reason, technology has been devised to detect the amount of foreign matter accumulated based on changes in electrostatic capacitance so that the timing of vacuum pump maintenance can be determined in advance.

[0004] In the invention disclosed in Patent Document 1 (paragraphs 0035 to 0039, Figure 2, etc.) listed below, a change in capacitance due to deposits accumulated between parallel plate electrodes is measured. In the invention disclosed in Patent Document 2 (paragraphs 0073, 0074, Figure 7, etc.), a change in capacitance due to deposits on the surfaces of interdigital electrodes is measured. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-159632 [Patent Document 2] Patent Publication No. 2021-195893 Summary of the Invention [Problem to be solved by the invention]

[0006] The invention disclosed in Patent Document 1 has the following problems. (1) Due to the lack of sufficient installation space, only small sensors can be installed, and sufficient detection sensitivity cannot be obtained. (2) The sensor blocks the gas flow path, adversely affecting exhaust performance. (3) It is not easy to extract the sensor signal from inside the pump to the outside.

[0007] In contrast, in the invention disclosed in Patent Document 2, the sensor is thin and can be installed on the surface of the gas flow path, so it does not block the gas flow path as in the invention disclosed in Patent Document 1. However, although it is possible to detect deposits when the thickness is small (thin), there is a problem in that as the thickness increases, the sensitivity decreases and detection becomes difficult.

[0008] An object of the present invention is to provide a foreign matter accumulation amount estimation device and a piping component that are capable of estimating the amount of accumulated foreign matter. [Means for solving the problem]

[0009] In order to achieve the above object, a foreign matter deposition amount estimation device according to the present invention comprises: a conductive casing having an inlet and an outlet; a conductor disposed inside the casing at a predetermined first distance from the casing; a measuring device for measuring the capacitance between the casing and the conductor; a computing device that estimates the amount of foreign matter accumulated in the casing from the change in capacitance; Equipped with. A piping part according to the present invention includes the above-described foreign matter accumulation amount estimation device. [Effects of the Invention]

[0010] According to the above invention, it is possible to provide a foreign matter accumulation amount estimation device capable of estimating the amount of accumulated foreign matter, and a piping component. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram showing a vacuum exhaust system including a piping component according to a first embodiment of the present invention. [Figure 2] 1 is an explanatory diagram schematically illustrating the configuration of a foreign matter deposition amount estimation device and a piping component according to a first embodiment of the present invention. [Figure 3] FIG. 10 is a perspective view showing a modified foreign matter deposition amount estimating device in which the conductive member has one communication opening. [Figure 4] FIG. 10 is an explanatory diagram showing a modified foreign matter deposition amount estimating device that controls temperature. [Figure 5] FIG. 10 is an explanatory diagram schematically illustrating the configuration of a foreign matter deposition amount estimation device and a piping component according to a second embodiment. [Figure 6] FIG. 10 is an explanatory diagram schematically illustrating the configuration of a foreign matter deposition amount estimation device and a piping component according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Outline of the first embodiment> Fig. 1 shows a vacuum pumping system 420 equipped with a piping component 410 according to a first embodiment of the present invention. In Fig. 1, the piping component 410 is hatched for emphasis. A foreign matter deposition amount estimation device 210 (Fig. 2) is formed in the piping component 410. The vacuum pumping system 420 shown in Fig. 1 is equipped with, for example, a processing chamber 422, a turbomolecular pump 100, a roughing pump 424, and the like that constitute a manufacturing device for semiconductors and the like (semiconductors, flat panels, etc.).

[0013] The processing chamber 422 and the turbomolecular pump 100 are connected by a pipe 426 so as to allow gas to flow therebetween. The turbomolecular pump 100 and the roughing pump 424 are connected by a pipe 428 so as to allow gas to flow therebetween. Known or common pumps can be used as the processing chamber 422, the turbomolecular pump 100, and the roughing pump 424. A pipe for supplying a purge gas may be connected to the turbomolecular pump 100. The vacuum exhaust system 420 may include a plurality of processing chambers 422, turbomolecular pumps 100, and roughing pumps 424, or a plurality of sets of the processing chambers 422, turbomolecular pumps 100, and roughing pumps 424.

[0014] The pipes 426, 428 can be configured by connecting a plurality of pipe components. Generally, there are many types of pipe components. Specifically, pipe components include straight pipes with a single pipe shape, elbow pipes with an L-shaped or other curved shape, and cross pipes with an X-shaped cross. In addition, pipe components include those with tapered pipe portions and those equipped with valves and various gauges (temperature gauges, pressure gauges, etc.). In this embodiment, a single pipe (straight type) pipe component 410 will be described as an example.

[0015] The piping component 410 is connected to a front-stage piping component 428A and a rear-stage piping component 428B. In the example of FIG. 1, the front-stage piping component 428A is shown as an L-shape, and the rear-stage piping component 428B is shown as a single pipe. However, this is not limited thereto, and the piping components 428A and 428B may be arranged in various configurations. Furthermore, the front-stage piping component 428A and the rear-stage piping component 428B may be configured by combining multiple piping components. Furthermore, the piping component 410 may be connected to the middle or end of the piping 426 between the processing chamber 422 and the turbomolecular pump 100.

[0016] 2 shows an enlarged view of a piping part 410. The piping part 410 is equipped with a foreign matter deposition amount estimation device 210. The foreign matter deposition amount estimation device 210 estimates the amount of deposition of foreign matter (reaction products) deposited inside the piping part 410. In the example of FIGS. 1 and 2, the deposits are generated when components of the exhaust gas from the turbomolecular pump 100 or components of a mixed gas of the exhaust gas and other gases (such as a purge gas) undergo chemical reactions or physical changes under environmental conditions such as temperature and pressure.

[0017] Foreign matter deposition amount estimation device 210 includes a casing 212 and a conductive member 214. Furthermore, foreign matter deposition amount estimation device 210 includes a measuring device 216 and a computing device 218. Note that in FIG. 2 showing the structure of foreign matter deposition amount estimation device 210 and piping component 410, hatching indicating cross sections of components has been omitted to avoid cluttering the drawing.

[0018] Although details will be described later, casing 212 and conductive member 214 constitute foreign object detection device (foreign object detection section) 220. Foreign object detection device 220 is electrically connected to measuring device 216, and the occurrence of foreign objects in foreign object detection device 220 is measured by measuring device 216. The measurement results of measuring device 216 are transmitted to computing device 218, and the occurrence of foreign objects is determined based on the results of calculations by computing device 218.

[0019] Foreign object detection device 220 has a double-tube structure made up of a casing 212 and a conductive member 214, similar to foreign object detection device 260 of the modified example shown in Fig. 3. Foreign object detection device 260 of the modified example shown in Fig. 3 differs from foreign object detection device 220 of Fig. 2 in the number of communication openings 236, which will be described later, etc.

[0020] However, here, the commonalities between the foreign object detection device 220 shown in Fig. 2 and the foreign object detection device 260 in Fig. 3 will be explained with reference to Fig. 3. In Fig. 3, the casing 212 and the conductive member 214 are shown with different shading densities.

[0021] 2, the casing 212 and the conductive member 214 are formed by processing a conductive material, such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals, into a cylindrical shape. Of these, the casing 212 is a single tubular member including a cylindrical portion 222, a first flange portion 224A, a second flange portion 224B, and an intermediate flange portion 226.

[0022] The first flange portion 224A and the second flange portion 224B are formed at each end in the axial direction of the casing 212. The first flange portion 224A is connected to a piping part 428A (FIG. 1) at the front stage, and the second flange portion 224B is connected to a piping part 428B (FIG. 1) at the rear stage. In the example of FIG. 2, the opening on the side of the first flange portion 224A is an inlet 225A of the casing 212, and the opening on the side of the second flange portion 224B is an outlet 225B of the casing 212.

[0023] Here, the term "casing" is used to mean, for example, a structure that has the function of covering at least a portion of the contents inside (such as the conductive member 214 in this case). Therefore, a structure with an open inlet 225A and an open outlet 225B, such as the casing 212, is also included in the term "casing." Note that other names for "casing" include, for example, a "tubular structure," a "tubular structure portion," a "target," a "target portion," a "gas introduction body," a "gas introduction portion," an "outer shell," and an "outer shell portion."

[0024] Although not shown, the connection between the first flange portion 224A and the upstream piping part 428A (FIG. 1) and / or the connection between the second flange portion 224B and the downstream piping part 428B (FIG. 1) can be performed, for example, by using a vacuum piping clamp with a center ring, which is a type of vacuum piping joint, sandwiched between them. Also, the connection between the casing 212 and the upstream piping part 428A (and / or the downstream piping part 428B) can also be performed by bolting.

[0025] Furthermore, the casing 212 may not be provided with a flange, and may be connected to the upstream piping part 428A or the downstream piping part 428B by welding. When welding is performed, the flange on the side to be welded (first flange part 224A and / or second flange part 224B) can be omitted.

[0026] The conductor member 214 is also formed in a single tube shape, and the outer diameter of the conductor member 214 is set to be smaller than the inner diameter of the casing 212. The wall thickness of the conductor member 214 is thinner than the wall thickness of the casing 212. The conductor member 214 is arranged concentrically (coaxially) inside the casing 212. A gap t (FIG. 2) is present between an outer peripheral surface 215 of the conductor member 214 and an inner peripheral surface 213 of the casing 212. This "gap" is also referred to as, for example, a "gap," a "distance," or an "inter-electrode distance." The size of the gap t is, for example, about 2 mm.

[0027] The conductor member 214 is supported inside the casing 212 while being suspended by the conductive pin 230. The conductive pin 230 and the conductor member 214 can be fixed together, for example, by screwing the tip of the conductive pin 230 into a connecting hole 232 of the conductor member 214. Here, the portion of the conductor member 214 into which the conductive pin 230 is screwed may be partially formed thicker so as to ensure a sufficient contact area (fastening force).

[0028] In addition, the fixing of the conductive pin 230 and the conductive member 214 is not limited to screwing, and can be done by various methods including press-fitting, as long as electricity can be passed between the conductive pin 230 and the conductive member 214.

[0029] The conductive pin 230 is formed by processing a conductive material such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals into a stepped cylindrical shape. The conductive pin 230 is inserted into a through-hole 228 formed in the intermediate flange portion 226. The through-hole 228 extends in the radial direction of the casing 212 (and the intermediate flange portion 226).

[0030] An O-ring 227 is attached to a relatively small diameter portion of the conductive pin 230. The O-ring 227 provides an airtight seal between the conductive pin 230 and the casing 212 inside the through-hole 228. Therefore, the O-ring 227 provides a vacuum sealing function. Furthermore, the conductive pin 230 is fixed to the casing 212 via the tightening force of a fixing nut 229 arranged on the outside of the intermediate flange portion 226.

[0031] Fixing nut 229 is formed using a conductive material such as stainless steel. A rectangular insulating plate 233 made of an electrically insulating material is sandwiched between fixing nut 229 and intermediate flange portion 226. Insulating plate 233 contacts a flattened seating surface of intermediate flange portion 226. Although not shown, a terminal (such as a round crimp terminal) that constitutes the end of an electrical wiring is sandwiched between fixing nut 229 and insulating plate 233.

[0032] As shown with reference to FIG. 3, four fixing screws 238 are used to fix the insulating plate 233. Although not shown, a terminal (such as a round crimp terminal) constituting the end of an electrical wiring is also sandwiched between the head of one of the four fixing screws 238 and the insulating plate 233. The conductive pin 230 connected to the electrical wiring (not shown) and the fixing screw 238 are used to apply a voltage (high-frequency voltage) for foreign object detection to the conductor member 214 and the casing 212. The value of the high-frequency voltage can be, for example, about 3 V (either a peak value or an effective value). The method of foreign object detection will be described later.

[0033] As shown in Fig. 2, the conductive member 214 is provided with a plurality of communication openings 236 (six in the example of Fig. 2). The communication openings 236 penetrate the casing 212 in the thickness direction (radial direction) and are arranged in a row at equal intervals along the axial direction of the conductive member 214. Furthermore, the opening dimensions of the communication openings 236 are the same. However, the foreign object detection device 260 according to the modified example of Fig. 3 is provided with only one communication opening 236, and in this respect, the foreign object detection device 220 of Fig. 2 differs from the foreign object detection device 260 of Fig. 3.

[0034] In the example of FIG. 2, a spacer 240 is inserted into the leftmost communication opening 236 (the end closest to the inlet 225A) of the multiple communication openings 236 lined up in a row. In FIG. 2, the spacer 240 is hatched for emphasis. An example of this spacer 240 is shown in FIG. 3, which is incorporated herein by reference. In the modified example of FIG. 3, only one spacer 240 is used, and it is inserted into only one communication opening 236. In addition, in the modified example of FIG. 3, there is no communication opening (communication opening 236) into which a spacer 240 is not inserted. In these respects as well, the foreign object detection device 220 of FIG. 2 differs from the foreign object detection device 260 of the modified example of FIG. 3.

[0035] 3, spacer 240 is formed by processing an electrically insulating material such as rubber (including other synthetic resins) or ceramics into a stepped pin shape. One axial end of spacer 240 is formed relatively thin and is inserted into communication opening 236.

[0036] The spacer 240 has the other axial end (the outer end of the conductor member 214) facing the inner circumferential surface 213 of the casing 212. One end of the spacer 240 is in contact with the inner circumferential surface 213 of the casing 212 and is interposed between the conductor member 214 and the casing 212. The spacer 240 maintains a gap between the conductor member 214 and the casing 212, while preventing the conductor member 214 from rotating (whirling) around the conductive pin 230 as a central axis.

[0037] In both the example of FIG. 2 and the modified example of FIG. 3, two spacers 240 are arranged at positions 180 degrees apart in phase in the circumferential direction of the conductive member 214. Furthermore, three or more spacers 240 (and communication openings 236) may be arranged at 120-degree or 90-degree intervals in the circumferential direction. Furthermore, the spacer 240 may be attached to the communication opening 236 located at the end closest to the outlet 225B. Furthermore, the spacer 240 may be attached to a communication opening 236 located at a position midway in a row. Furthermore, the spacer 240 may be attached to multiple communication openings 236 in a row.

[0038] <Detection of capacitance C> The fixing screw 238 (at least the fixing screw to which the wiring is connected) is electrically connected to the casing 212, and the conductive pin 230 is electrically connected to the conductive member 214. When a voltage is applied to the casing 212 and the conductive member 214 via the fixing screw 238 and the conductive pin 230, a potential difference occurs between the casing 212 and the conductive member 214. Because a gap t exists between the casing 212 and the conductive member 214, an electric charge Q (= CV) corresponding to the potential difference and the electrostatic capacitance is stored between the casing 212 and the conductive member 214.

[0039] In the above-mentioned Q=CV equation (hereafter referred to as "Equation (1)"), C is the capacitance and V is the potential difference. Since the potential difference V is known, the capacitance C can be calculated by detecting (measuring) the charge Q and performing the calculation (C=Q / V). Furthermore, by calculating the difference between the capacitances calculated at different times, the change in capacitance C (ΔC) over that time can be calculated.

[0040] Furthermore, the capacitance of a parallel plate conductor can be calculated by the formula C=εS / d (hereinafter referred to as "formula (2)"). The meanings of the symbols in formula (2) are as follows: C: capacitance ε: Dielectric constant (relative permittivity) of the material between the conductors S: opposing area of ​​conductor d: distance between conductors

[0041] 2 (and 3), the casing 212 and the conductive member 214 are cylindrical and concentrically arranged. The capacitance between the casing 212 and the conductive member 214 can be expressed using the equation for capacitance of a coaxial cylindrical conductor, C=(2πε) / (ln(b / a)) (hereinafter referred to as "Equation (3)"). Here, the meaning of each symbol is as follows: C: capacitance π: Pi ε: Dielectric constant (relative permittivity) of the material between the conductors a: outer diameter of the conductive member 214 b: inner diameter of casing 212 Also, ln is the natural logarithm.

[0042] As described above, the casing 212 and the conductive member 214 are connected to the measuring device 216, which is connected to the computing device 218. The casing 212 and the conductive member 214 serve as electrodes, forming a capacitance sensor. The measuring device 216 measures the electric charges of the casing 212 and the conductive member 214, and the computing device 218 calculates the capacitance and changes in capacitance at different times based on the measurement results of the measuring device 216. Note that the roles of the measuring device 216 and the computing device 218 are not limited to these. For example, some of the calculations may be performed in the measuring device 216, or all of the calculations may be performed in the computing device 218. Furthermore, the measuring device 216 and the computing device 218 may be integrated. Furthermore, the computing device 218 may be integrated with a control device of another device (for example, a control device of the turbomolecular pump 100).

[0043] 1 and 2, gas from the turbomolecular pump 100 flows into the foreign matter detection device 220, and the gas flows between the casing 212 and the conductive member 214 and inside the conductive member 214. The gas comes into contact with both the inner circumferential surface 213 of the casing 212 and the outer circumferential surface 215 of the conductive member 214. As a result, foreign matter (reaction products) is generated and accumulates on both the inner circumferential surface 213 of the casing 212 and the outer circumferential surface 215 of the conductive member 214. As the operating time of the turbomolecular pump 100 accumulates, the amount of foreign matter accumulated in the casing 212 and the amount of foreign matter accumulated on the conductive member 214 gradually increases.

[0044] As the thickness of the foreign matter increases, the gap t between the casing 212 and the conductive member 214 gradually closes, and as the gap t narrows, the capacitance between the casing 212 and the conductive member 214 increases. Then, the measuring device 216 measures the capacitance, and the computing device 218 calculates the amount of change in this capacitance, etc.

[0045] 1, gas is introduced into the foreign matter detection device 220 from the turbomolecular pump 100. Therefore, it can be considered that the change in capacitance in the foreign matter detection device 220 correlates with the accumulation of foreign matter inside the turbomolecular pump 100 and reflects the state of foreign matter accumulation. Therefore, by monitoring the change in capacitance in the foreign matter detection device 220, it is also possible to estimate the amount of foreign matter accumulated inside the turbomolecular pump 100.

[0046] <Utilizing temperature control> The amount of foreign matter accumulation varies depending on the pressure and temperature of the surrounding environment and the gas composition (type of gas). The amount of foreign matter accumulation can also be estimated by adjusting the temperature of the piping component 410. To adjust the temperature, for example, as shown in FIG. 4, an annular heater 290 can be attached to the outer periphery of the casing 212, and the heater 290 can be controlled by a temperature control device 292 to adjust the temperature inside the foreign matter detection device 220.

[0047] The temperature of the heater 290 can be controlled, for example, by providing a temperature sensor 294 in the casing 212 and having the temperature control device 292 refer to the output of the temperature sensor 294. The temperature sensor 294 can be disposed on the outside and / or inside of the casing 212.

[0048] <Output destination of estimation results> The estimation result (estimated amount of foreign matter) calculated by the arithmetic device 218 can be output to or connected to various types of computer equipment. Examples of the various types of computer equipment include a control device (not shown) for the turbomolecular pump 100, a control device (not shown) for the processing chamber 422, and integrated control devices owned by users of the turbomolecular pump 100 and the processing chamber 422. Examples of the various types of computer equipment also include inspection terminal devices carried by maintenance workers. Examples of the maintenance workers include maintenance workers for the turbomolecular pump 100, maintenance workers for the processing chamber 422, and maintenance workers for the vacuum pumping system including these.

[0049] <Representative Advantages of the Foreign Matter Deposition Amount Estimation Device 210 and the Pipe Component 410 According to the First Embodiment> According to the foreign matter deposition amount estimation device 210 of the first embodiment described above and the piping part 410 equipped with the foreign matter deposition amount estimation device 210, it is possible to estimate the amount of foreign matter deposited inside the casing 212 based on a change in capacitance inside the casing 212. In other words, it is possible to measure the change in capacitance inside the casing 212 and estimate the amount of foreign matter deposited inside the measured piping part 410 (and the foreign matter deposition amount estimation device 210 itself).

[0050] Furthermore, compared to the invention disclosed in Patent Document 1, for example, there are fewer restrictions on the sensor installation space (higher degree of freedom). Furthermore, since capacitance can be detected using a relatively large space, it is easy to increase the size of the capacitance sensor. Furthermore, it is easy to ensure a large electrode area (charged area) in the capacitance sensor, making it easy to improve detection sensitivity. Furthermore, the casing 212 and conductive member 214, which form the electrodes, are cylindrical, making it easier to ensure a large area compared to when the electrodes are flat. Furthermore, since the electrodes can be arranged in accordance with (or along) the shape of the pipe, the detection direction of the electrodes can be aligned with the direction of foreign matter accumulation (e.g., the radial direction of the pipe, a direction perpendicular to the axis of the pipe, etc.), allowing for more accurate understanding of the amount of foreign matter accumulated in the pipe.

[0051] Furthermore, because the conductive member 214 is cylindrical and arranged concentrically within the casing 212, it is possible to keep the capacitance sensor's proportion to the cross-sectional area of ​​the gas flow path small. This prevents the capacitance sensor from blocking the gas flow path and adversely affecting exhaust performance. There is no need to route the wiring through the gas flow path or narrow spaces, making it easy to route the wiring.

[0052] Furthermore, according to the foreign matter detection device 220 (FIG. 2) of the foreign matter deposition amount estimation device 210, the conductive member 214 has communication openings 236 that penetrate the conductive member 214 in the thickness direction. Therefore, gas that has flowed into the inside of the conductive member 214 can be guided to the gap t via the communication openings 236. This makes it easy for the gas to enter the gap t, and the gas has good fluidity. Furthermore, since a plurality of communication openings 236 are provided along the axial direction of the conductive member 214, it is possible to easily cause the gas to flow throughout the entire gap t.

[0053] More specifically, if the conductor member 214 were not provided with the communication port 236, the gas that has flowed into the inside of the conductor member 214 would flow toward the second flange portion 224B located downstream of the casing 212. Since the conductor member 214 is formed in a cylindrical shape, the entrance of the gas into the gap t would be limited to the end of the casing 212 on the side of the first flange portion 224A located upstream.

[0054] As a result, foreign matter is generated in a concentrated manner near the entrance to the gap t (the area on the side of the first flange portion 224A and the entrance 225A), and tends to be unevenly deposited near the entrance to the gap t (near the entrance 225A). As a result, the area near the entrance to the gap t is filled with deposits, making it difficult for gas to flow into the inner part of the gap t. Further gas is then prevented from flowing into the gap t, making it difficult for the gas to spread throughout the entire gap t.

[0055] However, by providing the communication opening 236 in the conductive member 214, it becomes possible to guide the gas from the inside of the conductive member 214 to the inner part of the gap t (towards the outlet 225B) through the communication opening 236. This makes it easier for the gas to penetrate the entire gap t, improving the fluidity of the gas. As a result, it is possible to prevent foreign matter from being unevenly accumulated near the entrance of the gap t (near the entrance 225A). This also makes it possible to more accurately measure the capacitance between the casing 212 and the conductive member 214.

[0056] Furthermore, since a plurality of communication ports 236 are provided along the axial direction of the conductive member 214, it is possible to easily cause gas to flow throughout the entire gap t. This also makes it possible to more accurately measure the capacitance between the casing 212 and the conductive member 214. Here, the arrangement of the plurality of communication ports 236 is not limited to a single row, and may be multiple rows or a staggered arrangement. Furthermore, the conductive member 214 may be formed using a punched metal or the like having a large number of holes.

[0057] In order to improve the fluidity of the gas, the conductor member 214 may be formed to have, for example, a semicircular (semi-cylindrical, arc-shaped) cross section, thereby opening a portion of the side surface (circumferential surface) of the conductor member 214. However, even in this case, there is a possibility that foreign matter may be unevenly deposited near the entrance of the gap t between the conductor member 214 with a semicircular (semi-cylindrical, arc-shaped) cross section and the casing 212. Therefore, providing multiple communication ports 236 in the axial direction in the conductor member 214 makes it easier to guide the gas throughout the gap t. Furthermore, even when the conductor member 214 has a semicircular (semi-cylindrical, arc-shaped) shape or another shape, the conductor member 214 may be formed using a punched metal or the like having a large number of holes.

[0058] Second Embodiment Next, a foreign matter deposition amount estimating device 310 according to a second embodiment of the present invention will be described with reference to Fig. 5. Note that the same parts as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0059] 5 shows a foreign matter detection device 320 of a foreign matter deposition amount estimation device 310 according to the second embodiment, and a piping part 430 equipped with the foreign matter detection device 320, together with a measuring device 216 and a computing device 218. In the example of FIG. 5, the foreign matter detection device 320 is equipped with two conductor members (a main conductor member 314A and a secondary conductor member 314B). As will be described in detail later, the secondary conductor member 314B functions as an auxiliary conductor.

[0060] The main conductor member 314A and the secondary conductor member 314B are both cylindrical and are aligned inside the casing 312 in the axial direction of the casing 312. The main conductor member 314A is positioned on the side of the second flange portion 224B, and the secondary conductor member 314B is positioned on the side of the first flange portion 224A. Furthermore, the main conductor member 314A and the secondary conductor member 314B are positioned concentrically with the casing 312.

[0061] An end 372 of the main conductor member 314A and an end 374 of the secondary conductor member 314B are machined perpendicular (vertical) to the axis, and face each other in parallel.

[0062] The main conductor member 314A is fixed to the conductive pin 330A, and is supported inside the casing 312 while being supported by the conductive pin 330A. Here, the conductive pin 330A can be the same as the conductive pin 230 in the first embodiment. The main conductor member 314A can be fixed to the conductive pin 330A by a method such as screwing, in the same manner as the conductor member 214 in the first embodiment is fixed to the conductive pin 230.

[0063] The secondary conductor member 314B is fixed to the conductive pin 330B and is supported inside the casing 312 while being suspended by the conductive pin 330B. Here, the conductive pin 330B may be the same as the conductive pin 230 in the first embodiment (and the conductive pin 330A of the main conductor member 314A). The secondary conductor member 314B can be fixed to the conductive pin 330B by a method such as screwing, in the same manner as the conductor member 214 in the first embodiment is fixed to the conductive pin 230.

[0064] A gap t is formed between the outer peripheral surface 315A of the main conductor member 314A and the inner peripheral surface 313 of the casing 312. A (distance between electrodes, Fig. 5) is present. A The size of the gap is the same as the gap t in the first embodiment (for example, 2 mm).

[0065] A gap t is formed between the outer peripheral surface 315B of the secondary conductor member 314B and the inner peripheral surface 313 of the casing 312. B (distance between electrodes, FIG. 5) is interposed. The outer diameter of the secondary conductor member 314B is set to be larger than the outer diameter of the primary conductor member 314A. Therefore, the gap t B The size of the gap t A smaller than (t A >t B) and the gap t B The size can be, for example, less than 2 mm (0.5 to 1.9 mm, preferably 0.8 to 1.6 mm, more preferably 1 mm to 1.4 mm).

[0066] In this way, by providing the secondary conductor member 314B, which has a different inter-electrode distance from the main conductor member 314A, inside the casing 312, it is possible to arrange two (or multiple) capacitance sensors in a common environment, one of which (some of which) reaches capacitance saturation earlier at different times. The capacitance sensor is formed by the combination of the main conductor member 314A and the casing 312, and the combination of the secondary conductor member 314B and the casing 312. Furthermore, the combination of the main conductor member 314A and the casing 312 functions as a main electrode, and the combination of the secondary conductor member 314B and the casing 312 functions as a secondary electrode.

[0067] Then, under the same environment, gaps of different sizes t A、 t B By forming the small side gap t B is the gap on the larger side t A The capacitance sensor (on the main conductor member 314A side) that saturates later than the capacitance sensor (on the secondary conductor member 314B side) and the capacitance sensor (on the secondary conductor member 314B side) that saturates earlier can be formed. By using the output signals related to the main conductor member 314A and the output signals related to the secondary conductor member 314B, it is possible to determine the type (component) of foreign matter using one electrode (the secondary conductor member 314B in this case) and then estimate the amount of foreign matter accumulation using the other electrode (the main conductor member 314A in this case).

[0068] More specifically, the gap t B In the capacitance sensor on the narrower side (the side of the secondary conductor member 314B), the gap t A The gap t B The gap t on the wider side is filled with foreign matter, and the capacitance becomes saturated. A Even in this case, the narrow gap tB It is thought that foreign matter has accumulated to a thickness similar to that of the narrow gap t B Since the size of is known, the gap on the wide side t A The thickness of the deposits at the site can be estimated.

[0069] Furthermore, the permittivity (relative permittivity) ε of the foreign matter can then be calculated from the above-mentioned equation (2) relating to the capacitance of the parallel plate conductor and equation (3) relating to the capacitance of the coaxial cylindrical conductor. Also, it is possible to estimate the type of foreign matter based on the calculated permittivity value. Also, the amount of foreign matter inside the piping part 410 can be calculated by the gap t A It is possible to estimate the capacitance using the capacitance sensor on the wider side (the side of the main conductor member 314A).

[0070] In the example of FIG. 5, an auxiliary measuring device 366 is provided as a measuring device for the secondary conductor member 314B. Similar to the measuring device 216 for the main conductor member 314A, the auxiliary measuring device 366 has the function of measuring the charges on the casing 312 and the secondary conductor member 314B. Furthermore, a correcting device 367 is connected to the auxiliary measuring device 366. The correcting device 367 has the function of determining the saturation of capacitance as described above based on the output of the auxiliary measuring device 366. Furthermore, the correcting device 367 has the function of correcting the amount of foreign matter accumulation calculated by the calculating device 218 for the main conductor member 314A.

[0071] The auxiliary measuring device 366 and the correction device 367 may be integrated. Furthermore, the correction device 367 may be integrated with the arithmetic device 218 or a control device of another device (for example, a control device of the turbomolecular pump 100). Furthermore, the measuring device 216 and the auxiliary measuring device 366 may be integrated, and the arithmetic device 218 and the correction device 367 may be integrated. Furthermore, the measuring device 216, the arithmetic device 218, the auxiliary measuring device 366, and the correction device 367 may be integrated.

[0072] In the second embodiment, the main conductor member 314A is located on the upstream side of the first flange portion 224A, and the secondary conductor member 314B is located on the downstream side of the second flange portion 224B, but this is not limiting. For example, the main conductor member 314A may be located downstream (near the second flange portion 224B), and the secondary conductor member 314B may be located upstream (near the first flange portion 224A).

[0073] In the second embodiment, the opposing ends 372, 374 of the main conductor member 314A and the secondary conductor member 314B are machined perpendicular (vertical) to the axial direction, but this is not limiting. Although not shown, for example, the opposing ends 372, 374 of the main conductor member 314A and the secondary conductor member 314B may be machined so that they are oblique to the axial direction and face each other. Alternatively, the main conductor member 314A and the secondary conductor member 314B may each be machined into a semicircular shape and face each other in the vertical direction in FIG. 5.

[0074] 5 according to the second embodiment, the spacer 240 is attached to the communication opening 236 in the main conductor member 314A that is closest to the inlet 225A and the communication opening 236 in the secondary conductor member 314B that is closest to the outlet 225B. However, this is not limiting, and the spacer 240 may be attached to any of the communication openings 236. Furthermore, the spacer 240 may be attached to multiple communication openings 236 in the main conductor member 314A and / or the secondary conductor member 314B. In FIG. 5, the spacer 240 is hatched for emphasis.

[0075] Third Embodiment Next, a foreign matter deposition amount estimating device 380 according to a third embodiment of the present invention will be described with reference to Fig. 6. Note that the same parts as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0076] FIG. 6 shows a foreign matter detector 390 of a foreign matter deposition amount estimation device 380 according to the third embodiment, and a piping component 440 equipped with the foreign matter detector 390, together with a measuring device 216 and a computing device 218. The example of FIG. 6 employs a structure similar to that of the first embodiment (FIG. 2). However, the axial length of the conductive member 384 is set to be longer than the axial length of the casing 382. Both axial ends of the conductive member 364 protrude (project) from the casing 382 in the axial direction. The casing 382 in the example of FIG. 6 has a shorter axial length than the casing 212 in the example of FIG. 2 according to the first embodiment. In FIG. 6, the spacer 240 is hatched for emphasis.

[0077] The foreign matter deposition amount estimation device 380 and the piping part 440 can extend the conductor member 384 into the piping parts connected to the front and rear (for example, piping parts 428A and 428B in FIG. 1). The longer the axial length of the conductor member 384, the greater the facing area with the piping parts connected to the front and rear.

[0078] The mating piping part is usually made of metal, and the piping part 440 and the mating piping part usually come into metal-to-metal contact (metal-to-metal contact). Furthermore, when a standardized vacuum piping fitting centering ring is used, when a vacuum piping clamp is used, when bolting is performed, or when welding is performed, metal-to-metal contact typically occurs. Therefore, electrical continuity is established between the piping part 440 and the mating piping part, and a foreign object detection device 390 can be formed using the mating piping part as a casing.

[0079] According to the foreign matter deposition amount estimation device 380 and piping component 440 of the third embodiment, it is possible to increase the area of ​​the electrodes by using other adjacent piping components. This makes it possible to improve the capacitance detection sensitivity. Furthermore, it is possible to improve the capacitance detection sensitivity at a lower cost than when the foreign matter deposition amount estimation device 380 (and piping component 440) is enlarged or when multiple foreign matter deposition amount estimation devices 380 (and piping components 440) are connected in series along the axial direction.

[0080] If the foreign matter deposition amount estimation device 380 (and piping component 440) is made larger, it may be difficult to place it in a limited, narrow installation space, making it difficult to handle. This also increases the cost of installing the foreign matter deposition amount estimation device 380 (and piping component 440). However, by utilizing the piping component to which it is connected, there is no need to increase the size of the foreign matter deposition amount estimation device 380 (and piping component 440), and the flexibility of handling increases. This makes it possible to prevent an increase in the cost of installing the foreign matter deposition amount estimation device 380 (and piping component 440).

[0081] The conductor member 384 may protrude (project) from the casing 212 only at one axial end of the foreign matter deposition amount estimation device 380 and the piping part 440. Even when the conductor member 384 protrudes from the casing 382 as in the third embodiment, at least a portion of the conductor member 384 exists inside the casing 382. Therefore, it can be said that the conductor member 384 is disposed inside the casing 382.

[0082] <Inventions that can be extracted from the embodiments> The following inventions can be extracted from the above-described embodiments. (1) a conductive casing (e.g., casing 212) having an inlet (e.g., inlet 225A) and an outlet (e.g., outlet 225B); The casing is spaced from the first distance (gap t, t Aa conductor (such as conductor members 214, 364, 384, main conductor member 314A, etc.) disposed inside the casing, a measuring device (such as measuring device 216) that measures the capacitance between the casing and the electrical conductor; a computing device (such as computing device 218) that estimates the amount of foreign matter accumulated in the casing from the change in capacitance; A foreign matter deposition amount estimation device comprising: (2) A second distance (gap t B a secondary conductor (such as the secondary conductor member 314B) disposed inside the casing, an auxiliary measuring device for measuring the capacitance between the casing and the auxiliary conductor; a correction device that corrects the amount of foreign matter accumulation based on the measurement result of the auxiliary measurement device; The foreign matter deposition amount estimation device according to (1) above, comprising: (3) a saturation determination device for determining saturation of the capacitance measured by the auxiliary measurement device in the correction device; The foreign matter deposition amount estimation device according to (2) above, comprising: (4) A communication hole (such as communication hole 236) in the conductor The foreign matter deposition amount estimation device according to any one of (1) to (3) above, comprising: (5) a temperature measuring device (such as the temperature sensor 294) disposed in the casing; a heater (such as heater 290) for heating the casing; a control device (such as a temperature control device 292) that controls the heater based on the measurement value of the temperature measurement device (such as the output of the temperature sensor 294); The foreign matter deposition amount estimation device according to any one of (1) to (3) above, comprising: (6) A piping component (such as piping components 410, 430, 440) equipped with the foreign matter deposition amount estimation device according to any one of (1) to (3) above.

[0083] <Other> The present invention is not limited to the above-described embodiments, and various modifications and combinations of the embodiments are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0084] 210, 310, 380: Foreign matter accumulation amount estimation device 212, 312, 382: Casing 213: Inner peripheral surface 214, 364, 384: Conductive members 215: Outer surface 216: Measuring equipment 218: Arithmetic device 220, 260, 320, 390: Foreign object detection device 224A: First flange 224B: Second flange part 225A: Entrance 225B:Exit 226: Intermediate flange 228: Through hole 229: Fixing nut 230: Conductive pin 233: Insulating plate 236: Connecting port 238: Fixing screw 240: Spacer 290: Heater 292: Temperature control device 294: Temperature sensor 313: Inner peripheral surface 314A: Main conductor member 314B: Sub-conductor member 315A: Outer surface 315B: Outer surface 330A: Conductive pin 330B: Conductive pin 366: Auxiliary measuring devices 367: Correction device 372: End 374: End 410, 430, 440: Piping parts 426, 428: Piping 428A, 428B: Piping parts t: gap t A :gap t B :gap

Claims

1. a conductive casing having an inlet and an outlet; a conductor disposed inside the casing at a predetermined first distance from the casing; a measuring device for measuring the capacitance between the casing and the conductor; a computing device that estimates the amount of foreign matter accumulated in the casing from the change in capacitance; A foreign matter deposition amount estimation device comprising:

2. an auxiliary conductor disposed inside the casing at a second distance from the casing that is smaller than the first distance; an auxiliary measuring device for measuring the capacitance between the casing and the auxiliary conductor; a correction device that corrects the amount of foreign matter accumulation based on the measurement result of the auxiliary measurement device; 2. The foreign matter deposition amount estimation device according to claim 1, further comprising:

3. a saturation determination device for determining saturation of the capacitance measured by the auxiliary measurement device; 3. The foreign matter deposition amount estimation device according to claim 2, further comprising:

4. A communication port is provided in the conductor.

4. The foreign matter deposition amount estimation device according to claim 1, further comprising:

5. a temperature measuring device disposed in the casing; a heater for heating the casing; a control device that controls the heater based on the measurement value of the temperature measuring device; 4. The foreign matter deposition amount estimation device according to claim 1, further comprising:

6. A piping part comprising the foreign matter deposition amount estimation device according to any one of claims 1 to 3.

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