Foreign matter accumulation estimation device and piping components

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, for example, to a device for estimating the amount of foreign matter accumulation that can be used in a vacuum system, and to piping components. [Background technology]

[0002] Turbomolecular pumps are generally known as a type of vacuum pump. These turbomolecular pumps are used, for example, for exhaust in manufacturing equipment for semiconductors and flat panels. In a turbomolecular pump, power is supplied to a motor inside the pump body to rotate a rotor, which then ejects the gas molecules (process gases) drawn into the pump body, thereby exhausting the gas. Some types of turbomolecular pumps are also equipped with heaters and cooling tubes to properly control the temperature inside the pump.

[0003] In vacuum pumps used for exhausting the air from manufacturing equipment for semiconductors and flat panels, reaction products (foreign matter) generated 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 cause problems such as collisions with rotating parts. For this reason, a technology has been devised to detect the amount of foreign matter accumulated based on changes in capacitance, so that the timing of maintenance inside the vacuum pump can be determined in advance.

[0004] In the invention disclosed in Patent Document 1 (paragraphs 0035-0039, Figure 2, etc.), the change in capacitance due to deposits accumulated between parallel plate electrodes is measured. In addition, in the invention disclosed in Patent Document 2 (paragraphs 0073, 0074, Figure 7, etc.), the change in capacitance due to deposits on the surface of a comb-shaped electrode is measured. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-159632 [Patent Document 2] Japanese Patent Publication No. 2021-195893 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The invention disclosed in Patent Document 1 has the following problems: (1) Due to insufficient installation space, only small sensors can be installed, resulting in insufficient detection sensitivity. (2) The sensor may block the gas flow path, negatively affecting exhaust performance. (3) It is not easy to extract sensor signals from inside the pump to the outside.

[0007] In contrast, the invention disclosed in Patent Document 2 has a thin sensor and can be installed on the surface of the gas channel, so it does not block the gas channel like the invention disclosed in Patent Document 1. However, while it can detect when the deposit thickness is small (thin), there is a problem that the sensitivity decreases as the thickness increases, making detection difficult.

[0008] The object of the present invention is to provide a foreign matter accumulation amount estimation device and piping components that can estimate the amount of foreign matter accumulated. [Means for solving the problem]

[0009] To achieve the above objective, the foreign matter accumulation amount estimation device according to the present invention is A conductive casing with 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 deposited inside the casing from the change in capacitance, Equipped with, The conductor is arranged along the entire inner surface of the casing. It has a portion and a portion that is partially missing and arranged along a part of the inner surface of the casing, and forms a double-tube structure with the casing.. Further, the piping component according to the present invention is provided with the above foreign matter deposition amount estimation device. [Effects of the Invention]

[0010] According to the above invention, it is possible to provide a foreign matter deposition amount estimation device capable of estimating the deposition amount of foreign matter, and a piping component. [Brief Description of the Drawings]

[0011] [Figure 1] This is an explanatory diagram showing a vacuum exhaust system provided with the piping component according to the first embodiment of the present invention. [Figure 2] This is an explanatory diagram schematically showing the configurations of the foreign matter deposition amount estimation device and the piping component according to the first embodiment of the present invention. [Figure 3] This is a perspective view showing a foreign matter deposition amount estimation device of a modified example in which the conductor member has one communication port. [Figure 4] This is an explanatory diagram showing a foreign matter deposition amount estimation device of a modified example that performs temperature control. [Figure 5] This is an explanatory diagram schematically showing the configurations of the foreign matter deposition amount estimation device and the piping component according to the second embodiment. [Figure 6] This is an explanatory diagram schematically showing the configurations of the foreign matter deposition amount estimation device and the piping component according to the third embodiment. [Modes for Carrying Out the Invention]

[0012] <Overview of First Embodiment> Figure 1 shows a vacuum exhaust system 420 provided with a piping component 410 according to the first embodiment of the present invention. In Figure 1, the piping component 410 is hatched for emphasis. The foreign matter deposition amount estimation device 210 (Figure 2) is formed in the piping component 410. The vacuum exhaust system 420 shown in Figure 1 is provided with, for example, a processing chamber 422 constituting a manufacturing apparatus for semiconductors and the like (semiconductors, flat panels and the like), a turbo molecular pump 100, a roughing pump 424, and the like.

[0013] The processing chamber 422 and the turbomolecular pump 100 are connected by piping 426 to allow gas flow. The turbomolecular pump 100 and the roughing pump 424 are also connected by piping 428 to allow gas flow. Known or common components can be used for the processing chamber 422, turbomolecular pump 100, and roughing pump 424. Piping for supplying purge gas may be connected to the turbomolecular pump 100. Furthermore, the vacuum exhaust system 420 may include multiple processing chambers 422, turbomolecular pumps 100, and roughing pumps 424, or multiple sets thereof.

[0014] Piping 426 and 428 can be constructed by connecting multiple piping components. In general, there are many types of piping components. Specifically, piping components include straight pipes, elbows with curved shapes such as L-shapes, and cross pipes that intersect in an X-shape. In addition, some piping components have tapered sections, and others are equipped with valves and various gauges (temperature gauges, pressure gauges, etc.). In this embodiment, a straight pipe component 410 will be described as an example.

[0015] The piping component 410 is connected to the preceding piping component 428A and the succeeding piping component 428B. In the example in Figure 1, the preceding piping component 428A is shown in an L-shape, and the succeeding piping component 428B is shown as a single pipe. However, it is not limited to these, and the piping components 428A and 428B may be arranged in various configurations. Furthermore, the preceding piping component 428A and the succeeding piping component 428B may be composed of a combination of multiple piping components. In addition, it is also possible to connect the piping component 410 to the middle or end of the piping 426 between the processing chamber 422 and the turbomolecular pump 100.

[0016] Figure 2 shows a magnified view of the piping component 410. The piping component 410 is equipped with a foreign matter accumulation estimation device 210. The foreign matter accumulation estimation device 210 estimates the amount of foreign matter (reaction products) accumulated inside the piping component 410. In the examples in Figures 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 purge gas), undergo chemical reactions and physical changes under environmental conditions such as temperature and pressure.

[0017] The foreign matter accumulation estimation device 210 comprises a casing 212 and a conductive member 214. Furthermore, the foreign matter accumulation estimation device 210 comprises a measuring device 216 and a calculation device 218. Note that in Figure 2, which shows the structure of the foreign matter accumulation estimation device 210 and the piping component 410, the hatching indicating the cross-section of the component has been omitted to avoid making the drawing cluttered.

[0018] As will be described in detail later, the casing 212 and the conductive member 214 constitute the foreign object detection device (foreign object detection unit) 220. The foreign object detection device 220 is electrically connected to the measuring device 216, and the foreign object generation status in the foreign object detection device 220 is measured by the measuring device 216. The measurement results from the measuring device 216 are transmitted to the calculation unit 218, and the foreign object generation status is determined based on the calculation results of the calculation unit 218.

[0019] The foreign object detection device 220 has a double-tube structure consisting of a casing 212 and a conductive member 214, similar to the modified foreign object detection device 260 shown in Figure 3. The modified foreign object detection device 260 shown in Figure 3 and the foreign object detection device 220 in Figure 2 differ in the number of communication ports 236, which will be described later.

[0020] However, regarding the foreign object detection device 220 shown in Figure 2, the commonalities with the foreign object detection device 260 shown in Figure 3 will be explained by referring to Figure 3. In addition, in the referenced Figure 3, the casing 212 and the conductive member 214 are shown with different shaded concentrations.

[0021] In the foreign object detection device 220 shown in Figure 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 these metals as components into a cylindrical shape. Of these, the casing 212 is a single-tube member having 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 the axial ends of the casing 212. The first flange portion 224A is connected to the preceding piping component 428A (Figure 1), and the second flange portion 224B is connected to the subsequent piping component 428B (Figure 1). In the example in Figure 2, the opening on the side of the first flange portion 224A is the inlet 225A of the casing 212, and the opening on the side of the second flange portion 224B is the outlet 225B of the casing 212.

[0023] Here, the term "casing" is used to mean a structure that has the function of covering at least a part of its internal components (in this case, the conductive member 214). For this reason, structures with open inlet 225A and outlet 225B, such as casing 212, are also included in the definition of "casing." Other names for "casing" include, for example, "tubular structure," "tubular structural part," "target," "target part," "gas inlet," "gas inlet part," "outer shell," and "outer shell part."

[0024] The connection between the first flange portion 224A and the preceding piping component 428A (Figure 1), and / or the connection between the second flange portion 224B and the subsequent piping component 428B (Figure 1), can be made using a vacuum piping clamp with a centering ring, a type of vacuum piping fitting, in between, although this is not shown in the diagram. Furthermore, the connection between the casing 212 and the preceding piping component 428A (and / or the subsequent piping component 428B) can also be made by bolting.

[0025] Furthermore, the casing 212 may be connected to the preceding piping component 428A and the subsequent piping component 428B by welding, without providing a flange portion. Also, if welding is performed, the flange portion on the side to be welded (first flange portion 224A and / or second flange portion 224B) can be omitted.

[0026] The conductive member 214 is also formed in a single-tube shape, and the outer diameter of the conductive member 214 is set to be smaller than the inner diameter of the casing 212. The wall thickness of the conductive member 214 is thinner than the wall thickness of the casing 212. The conductive member 214 is arranged concentrically (coaxially) inside the casing 212. A gap t (Figure 2) is interposed between the outer circumferential surface 215 of the conductive member 214 and the inner circumferential surface 213 of the casing 212. This "gap" is also called, for example, "interval," "distance," or "distance between electrodes." The size of the gap t is, for example, about 2 mm.

[0027] The conductive member 214 is supported inside the casing 212, suspended by conductive pins 230. The conductive pins 230 and the conductive member 214 can be fixed, for example, by screwing the tip of the conductive pin 230 into the connecting hole 232 of the conductive member 214. Here, the portion of the conductive member 214 into which the conductive pins 230 are screwed may be partially thickened to obtain a sufficient contact area (fastening force).

[0028] Furthermore, the conductive pin 230 and the conductive member 214 can be fixed together by various methods, including press-fitting, rather than just screwing, as long as current 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 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 radially through the casing 212 (and the intermediate flange portion 226).

[0030] An O-ring 227 is fitted to the relatively small diameter portion of the conductive pin 230. Inside the through hole 228, the space between the conductive pin 230 and the casing 212 is hermetically sealed by the O-ring 227. As a result, 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 located on the outside of the intermediate flange portion 226.

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

[0032] As shown with reference to Figure 3, four fixing screws 238 are used to secure the insulating plate 233. Although not shown in the figure, a terminal (such as a ring crimp terminal) that constitutes the end of the electrical wiring is also sandwiched between the head of one of the four fixing screws 238 and the insulating plate 233. The conductive pins 230 connected to the electrical wiring (not shown) and the fixing screws 238 are used to apply a voltage (high-frequency voltage) for foreign object detection to the conductive member 214 and the casing 212. The value of the high-frequency voltage can be, for example, about 3V (either peak value or RMS value). The method of foreign object detection will be described later.

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

[0034] In the example in Figure 2, a spacer 240 is inserted into the leftmost communication port 236 (the end closest to the inlet 225A) of the multiple communication ports 236 arranged in a row. In Figure 2, the spacer 240 is hatched for emphasis. An example of this spacer 240 is shown in the referenced Figure 3. In the modified example in Figure 3, only one spacer 240 is used and inserted into only one communication port 236. Furthermore, in the modified example in Figure 3, there are no communication ports (communication ports 236) that do not have a spacer 240 inserted. In these respects, the foreign object detection device 220 in Figure 2 differs from the foreign object detection device 260 of the modified example in Figure 3.

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

[0036] Furthermore, the other end of the spacer 240 in the axial direction (the outer end of the conductive member 214) is directed toward 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 the spacer 240 is interposed between the conductive member 214 and the casing 212. The spacer 240 ensures the distance between the conductive member 214 and the casing 212 while preventing the conductive member 214 from rotating (swinging) around the conductive pin 230 as its central axis.

[0037] In both the example in Figure 2 and the modified example in Figure 3, two spacers 240 are arranged circumferentially around the conductive member 214 at positions separated by a phase of 180 degrees. Furthermore, three or more spacers 240 (and communication openings 236) may be arranged circumferentially at intervals of 120° or 90°. Also, a spacer 240 may be attached to a communication opening 236 located at the end closest to the outlet 225B. Furthermore, a spacer 240 may be attached to a communication opening 236 located in the middle of a row. In addition, a spacer 240 may be attached to multiple communication openings 236 in a row.

[0038] <Detection of capacitance C> The fixing screws 238 (at least the fixing screws to which the wiring is connected) are connected to the casing 212 in a state where current can flow, and the conductive pins 230 are connected to the conductive member 214 in a state where current can flow. When a voltage is applied to the casing 212 and the conductive member 214 via the fixing screws 238 and the conductive pins 230, a potential difference is created between the casing 212 and the conductive member 214. Since there is a gap t between the casing 212 and the conductive member 214, a charge Q (=CV) corresponding to the potential difference and capacitance is accumulated between the casing 212 and the conductive member 214.

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

[0040] Furthermore, the capacitance of a parallel plate conductor can be calculated using the formula C = εS / d (hereinafter referred to as "formula (2)"). The meaning of each symbol in equation (2) is as follows. C: Capacitance ε: Dielectric constant (relative dielectric constant) of materials between conductors S: Facing area of ​​the conductor d: distance between conductors

[0041] In the example shown in Figure 2 (and Figure 3), the casing 212 and the conductive member 214 are cylindrical and arranged concentrically. The capacitance between the casing 212 and the conductive member 214 can be expressed using the capacitance equation for 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 dielectric constant) of materials between conductors a: Outer diameter of conductive member 214 b: Inner diameter of casing 212 Furthermore, ln is the natural logarithm.

[0042] As described above, the casing 212 and the conductive member 214 are connected to the measuring device 216, and the measuring device 216 is connected to the calculation device 218. The casing 212 and the conductive member 214 act as electrodes to each other, forming a capacitance sensor. The measuring device 216 measures the charge of the casing 212 and the conductive member 214, and the calculation device 218 calculates the capacitance and the change in capacitance at different timings based on the measurement results from the measuring device 216. However, the roles of the measuring device 216 and the calculation device 218 are not limited to these. For example, some calculations may be performed in the measuring device 216, or all calculations may be performed in the calculation device 218. Furthermore, the measuring device 216 and the calculation device 218 may be integrated. In addition, the calculation device 218 may be integrated with the control device of another device (for example, the control device of the turbomolecular pump 100).

[0043] In the examples shown in Figures 1 and 2, gas from the turbomolecular pump 100 flows into the foreign matter detection device 220, and the incoming 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 deposited on both the inner circumferential surface 213 of the casing 212 and the outer circumferential surface 215 of the conductive member 214. Then, as the operating time of the turbomolecular pump 100 increases cumulatively, the amount of foreign matter deposited on the casing 212 and the conductive member 214 gradually increases.

[0044] As the thickness of the foreign material increases, the gap t between the casing 212 and the conductive member 214 is gradually filled, and as the gap t narrows, the capacitance between the casing 212 and the conductive member 214 increases. Then, the capacitance is measured in the measuring device 216, and the calculation device 218 performs calculations on the amount of change related to this capacitance.

[0045] In the vacuum exhaust system example shown in Figure 1, gas from the turbomolecular pump 100 is introduced into the foreign matter detection device 220. Therefore, it can be considered that changes in capacitance in the foreign matter detection device 220 correlate with the accumulation of foreign matter inside the turbomolecular pump 100 and reflect the state of foreign matter accumulation. Thus, by monitoring changes in capacitance in the foreign matter detection device 220, it is possible to estimate the amount of foreign matter accumulated inside the turbomolecular pump 100.

[0046] <Utilization of temperature control> The amount of foreign matter accumulation varies depending on the pressure and temperature of the surrounding environment, as well as the composition (type of gas) of the gas. It is also possible to estimate the amount of foreign matter accumulation by adjusting the temperature of the piping component 410. For temperature adjustment, for example, as shown in Figure 4, an annular heater 290 can be attached to the outer circumference 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 the temperature control device 292 referencing the output of the temperature sensor 294. The temperature sensor 294 can be placed on the outside and / or inside of the casing 212.

[0048] <Output destination for estimation results> Various computer devices can be used as the output destination for the estimation results (estimated amount of foreign matter) calculated by the computing device 218, or as the connection destination for the computing device 218. Examples of various computer devices include the control device for the turbomolecular pump 100 (not shown), the control device for the processing chamber 422 (not shown), and integrated control equipment owned by the users of the turbomolecular pump 100 and the processing chamber 422. Furthermore, examples of various computer devices include inspection terminal equipment carried by maintenance workers. Examples of maintenance workers include maintenance workers for the turbomolecular pump 100, maintenance workers for the processing chamber 422, and maintenance workers for the vacuum exhaust system including these.

[0049] <Typical advantages of the foreign matter accumulation amount estimation device 210 and piping component 410 according to the first embodiment> According to the foreign matter accumulation amount estimation device 210 of the first embodiment described above, and the piping component 410 equipped with the foreign matter accumulation amount estimation device 210, it is possible to estimate the amount of foreign matter accumulated inside the casing 212 based on the 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 accumulated inside the measured piping component 410 (and the foreign matter accumulation amount estimation device 210 itself).

[0050] Furthermore, compared to the invention disclosed in the aforementioned Patent Document 1, for example, there are fewer constraints on the installation space of the sensor (higher degree of freedom). In addition, capacitance can be detected using a relatively large space, making it easy to enlarge the capacitance sensor. Moreover, it is easy to secure a large electrode area (charging area) in the capacitance sensor, making it easy to increase detection sensitivity. Furthermore, since the casing 212 and conductive member 214 that serve as electrodes are cylindrical, it is easier to secure a larger area compared to when the electrodes are flat. Also, since the electrodes can be arranged along (or beside) the shape of the pipe, the detection direction of the electrodes can be aligned with the direction of accumulation of foreign matter (for example, the radial direction of the pipe, the direction perpendicular to the axis of the pipe, etc.), making it possible to more accurately grasp the amount of foreign matter accumulated in the pipe.

[0051] Furthermore, because the conductive member 214 is cylindrical and concentrically arranged within the casing 212, the proportion of the capacitance sensor's area in the gas flow path can be kept small. This prevents the capacitance sensor from blocking the gas flow path and negatively affecting exhaust performance. Wiring is also easier as there is no need to route the wires through gas flow paths or narrow spaces.

[0052] Furthermore, according to the foreign matter detection device 220 (Figure 2) of the foreign matter accumulation estimation device 210, the conductive member 214 has a communication port 236 that penetrates the conductive member 214 in the thickness direction. Therefore, gas that flows into the inside of the conductive member 214 can be guided into the gap t through the communication port 236. Thus, it is easy to allow gas to enter the gap t, and the gas has good fluidity. Moreover, since there are multiple communication ports 236 provided along the axial direction of the conductive member 214, it is possible to easily allow gas to flow throughout the entire gap t.

[0053] More specifically, if the conductive member 214 is not provided with a communication port 236, the gas that flows into the inside of the conductive member 214 will flow towards the second flange portion 224B located downstream of the casing 212. And, since the conductive member 214 is formed in a cylindrical shape, the gas inlet into the gap t will be limited to the end on the upstream side of the casing 212, on the first flange portion 224A side.

[0054] As a result, foreign matter tends to concentrate 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 accumulate unevenly near the entrance to the gap t (near the entrance 225A). Consequently, the area near the entrance to the gap t becomes filled with sediment, making it difficult for gas to flow into the deeper parts of the gap t. Furthermore, the inflow of gas into the gap t is prevented, making it difficult to distribute the gas throughout the entire gap t.

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

[0056] Furthermore, since multiple communication ports 236 are provided along the axial direction of the conductive member 214, gas can be easily flowed throughout the entire gap t. This also makes it possible to measure the capacitance between the casing 212 and the conductive member 214 more accurately. Here, the arrangement of the multiple communication ports 236 is not limited to a single row, but may be in multiple rows or a staggered arrangement. Also, the conductive member 214 may be formed using perforated metal or the like with many holes.

[0057] Furthermore, in order to improve the fluidity of the gas, the conductive member 214 may be formed to have a semicircular (semi-cylindrical, arc-shaped) cross-section, for example, by leaving a portion of the side surface (circumferential surface) of the conductive member 214 open. However, even in this case, there is a possibility that foreign matter may accumulate unevenly near the entrance of the gap t between the conductive member 214 with a semicircular (semi-cylindrical, arc-shaped) cross-section and the casing 212. Therefore, it is easier to guide the gas throughout the gap t if the conductive member 214 is provided with multiple communication openings 236 along the axial direction. In addition, when the shape of the conductive member 214 is semicircular (semi-cylindrical, arc-shaped) or other shapes, the conductive member 214 may be formed using perforated metal or the like with a large number of holes.

[0058] <Second Embodiment> Next, a foreign matter accumulation amount estimation device 310 according to the second embodiment of the present invention will be described with reference to Figure 5. Note that parts similar to those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0059] Figure 5 shows the foreign matter detection device 320 of the foreign matter accumulation amount estimation device 310 according to the second embodiment, and the piping component 430 equipped therewith, together with the measuring device 216 and the calculation device 218. In the example in Figure 5, the foreign matter detection device 320 is equipped with two conductive members (main conductive member 314A and sub-conductive member 314B). As will be described in detail later, the sub-conductive member 314B functions as an auxiliary conductor.

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

[0061] The end portion 372 of the main conductive member 314A and the end portion 374 of the sub-conductive member 314B are machined perpendicular to the axis and face each other parallel to one another.

[0062] The main conductive member 314A is fixed to the conductive pin 330A and is supported inside the casing 312 by the conductive pin 330A. Here, the conductive pin 330A can be the same as the conductive pin 230 in the first embodiment. Furthermore, the main conductive member 314A can be fixed to the conductive pin 330A by screwing or other methods, in the same way as the conductive member 214 is fixed to the conductive pin 230 in the first embodiment.

[0063] The sub-conductive member 314B is fixed to the conductive pin 330B and is supported inside the casing 312 while suspended by the conductive pin 330B. Here, the conductive pin 330B can be the same as the conductive pin 230 (and the conductive pin 330A of the main conductive member 314A) in the first embodiment. Furthermore, the sub-conductive member 314B can be fixed to the conductive pin 330B by screwing or other methods, similar to how the conductive member 214 is fixed to the conductive pin 230 in the first embodiment.

[0064] There is a gap t between the outer circumferential surface 315A of the main conductive member 314A and the inner circumferential surface 313 of the casing 312. A (Distance between electrodes, Figure 5) is present. A The size of this element is similar to the gap t in the first embodiment (for example, 2 mm).

[0065] There is a gap t between the outer circumferential surface 315B of the auxiliary conductive member 314B and the inner circumferential surface 313 of the casing 312. B (Distance between electrodes, Figure 5) is present. The outer diameter of the sub-conductor member 314B is set to be larger than the outer diameter of the main conductor member 314A. Therefore, a gap t B The size is the gap t related to the main conductive member 314A. A Smaller than (t A >t B). Then, the gap t B can be set to, 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), and the like.

[0066] In this way, by providing the sub-conductor member 314B having a different inter-electrode distance from the main conductor member 314A inside the casing 312, it is possible to arrange two (a plurality of) capacitance sensors with different timings at which the capacitance of one (a part) is saturated earlier in a common environment. The capacitance sensors are formed by the combination of the main conductor member 314A and the casing 312, and the combination of the sub-conductor member 314B and the casing 312. Further, the combination of the main conductor member 314A and the casing 312 functions as a main electrode, and the combination of the sub-conductor member 314B and the casing 312 functions as a sub-electrode.

[0067] Then, in a common environment, gaps t with different sizes A、 t B are formed, so that the smaller gap t B is filled with foreign matter earlier than the larger gap t A , and the capacitance C is saturated accordingly. Therefore, a capacitance sensor with slow saturation (on the side of the main conductor member 314A) and a capacitance sensor with fast saturation (on the side of the sub-conductor member 314B) can be formed. Then, by using the output signal related to the main conductor member 314A and the output signal related to the sub-conductor member 314B, the type (component) of the foreign matter can be grasped using one electrode (here, the sub-conductor member 314B), and then the deposition amount of the foreign matter can be estimated using the other electrode (here, the main conductor member 314A).

[0068] More specifically, in the capacitance sensor on the side with the narrower gap t B (on the side of the sub-conductor member 314B), compared with the capacitance sensor on the side with the wider gap t A (on the side of the main conductor member 314A), the gap t B is filled with foreign matter earlier, and the capacitance is saturated. At this time, also in the wider gap t A , in the narrower gap t on the sideB It is thought that foreign matter is accumulating with a similar thickness, and the gap on the narrower side t B Since the size is known, the gap t on the wider side A The thickness of the sediment in that area can be estimated.

[0069] Furthermore, the dielectric constant (relative dielectric constant) ε of the foreign matter can then be calculated from the aforementioned equation (2) relating to the capacitance of the parallel plate conductor and equation (3) relating to the capacitance of the coaxial cylindrical conductor. It is also possible to estimate the type of foreign matter based on the calculated dielectric constant value. Additionally, the amount of foreign matter inside the piping component 410 is determined by the gap t. A It is possible to estimate the capacitance using the capacitance sensor on the side with the wider capacitance (the side of the main conductive member 314A).

[0070] In the example shown in Figure 5, an auxiliary measuring device 366 is provided as a measuring device for the subconducting member 314B. The auxiliary measuring device 366 has the function of measuring the charge of the casing 312 and the subconducting member 314B, similar to the measuring device 216 for the main conductive member 314A. Furthermore, a correction device 367 is connected to the auxiliary measuring device 366. The correction device 367 has the function of determining the capacitance saturation, as described above, based on the output of the auxiliary measuring device 366. Furthermore, the correction device 367 has the function of correcting the amount of foreign matter deposited, which is calculated by the calculation device 218 for the main conductive 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 unit 218 or the control device of other equipment (for example, the control device of the turbomolecular pump 100). Also, the measuring device 216 and the auxiliary measuring device 366 may be integrated, and the arithmetic unit 218 and the correction device 367 may be integrated. Furthermore, the measuring device 216, the arithmetic unit 218, the auxiliary measuring device 366, and the correction device 367 may be integrated.

[0072] In the second embodiment, the main conductive member 314A is located on the side of the first flange portion 224A, which is located upstream, and the sub-conductive member 314B is located on the side of the second flange portion 224B, which is located downstream. However, the embodiment is not limited to this. For example, the main conductive member 314A may be located downstream (on the side of the second flange portion 224B), and the sub-conductive member 314B may be located upstream (on the side of the first flange portion 224A).

[0073] Furthermore, in the second embodiment, the opposing ends 372 and 374 of the main conductive member 314A and the sub-conducting member 314B are machined perpendicular (vertical) to the axial direction, but the invention is not limited to this. Although not shown in the figures, for example, the opposing ends 372 and 374 of the main conductive member 314A and the sub-conducting member 314B may be machined diagonally with respect to the axial direction and facing each other. Alternatively, the main conductive member 314A and the sub-conducting member 314B may each be machined into a semicircular shape and positioned to face each other in the vertical direction shown in Figure 5.

[0074] Furthermore, in the example shown in Figure 5 according to the second embodiment, the spacer 240 is attached to the communication opening 236 closest to the inlet 225A in the main conductor member 314A and to the communication opening 236 closest to the outlet 225B in the sub-conductor member 314B. However, it is not limited to this, and the spacer 240 may be attached to any of the communication openings 236. Moreover, the spacer 240 may be attached to multiple communication openings 236 in the main conductor member 314A and / or the sub-conductor member 314B. In Figure 5, the spacer 240 is hatched for emphasis.

[0075] <Third Embodiment> Next, a foreign matter accumulation amount estimation device 380 according to the third embodiment of the present invention will be described with reference to Figure 6. Note that parts similar to those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0076] Figure 6 shows the foreign matter detection device 390 of the foreign matter accumulation amount estimation device 380 according to the third embodiment, and the piping component 440 equipped therewith, together with the measuring device 216 and the calculation device 218. In the example of Figure 6, a structure similar to that of the first embodiment (Figure 2) is adopted. However, the axial length of the conductive member 384 is set to be greater than the axial length of the casing 382. Furthermore, both axial ends of the conductive member 364 protrude (project) from the casing 382 in the axial direction. Note that the casing 382 in the example of Figure 6 is set to be shorter in the axial direction than the casing 212 in the example of Figure 2 according to the first embodiment. In Figure 6, the spacer 240 is hatched for emphasis.

[0077] Such a foreign matter accumulation estimation device 380 and piping component 440 can also allow the conductive member 384 to reach into piping components connected to the front and rear (for example, piping components 428A and 428B as shown in Figure 1). Increasing the axial length of the conductive member 384 increases the surface area facing the piping components connected to it at the front and rear.

[0078] The connecting piping component is usually made of metal, and the piping component 440 and the connecting piping component are typically in metal-to-metal contact. Furthermore, when a centering ring of a standardized vacuum piping fitting is interposed, when a vacuum piping clamp is used, when bolting is performed, or when welding is performed, metal-to-metal contact usually occurs. As a result, the piping component 440 and the connecting piping component are electrically conductive, and a foreign object detection device 390 can be formed using the connecting piping component as a casing.

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

[0080] If the foreign matter accumulation estimation device 380 (and piping component 440) is enlarged, it may be difficult to place it in a limited, narrow installation space, making it difficult to handle. Furthermore, the cost of installing the foreign matter accumulation estimation device 380 (and piping component 440) will increase. However, by utilizing the piping component to which it is connected, it becomes unnecessary to enlarge the foreign matter accumulation estimation device 380 (and piping component 440), increasing the flexibility of handling. This prevents an increase in the cost of installing the foreign matter accumulation estimation device 380 (and piping component 440).

[0081] Furthermore, the conductive member 384 may protrude from the casing 212 only at one axial end of the foreign matter accumulation estimation device 380 and the piping component 440. Also, even when the conductive member 384 protrudes from the casing 382, ​​as in the third embodiment, at least a portion of the conductive member 384 is located inside the casing 382. Therefore, it can be said that the conductive member 384 is disposed inside the casing 382.

[0082] <Inventions that can be extracted from the embodiments> From the embodiments described above, the following inventions can be extracted. (1) A conductive casing (casing 212, etc.) having an inlet (inlet 225A, etc.) and an outlet (outlet 225B, etc.), The casing and a predetermined first distance (gap t, t) AThe size of the conductor (conductive members 214, 364, 384, main conductive member 314A, etc.) and the conductive members (conductive members 214, 364, 384, main conductive member 314A, etc.) arranged inside the casing, A measuring device (such as measuring device 216) for measuring the capacitance between the casing and the conductor, A calculation device (such as calculation device 218) that estimates the amount of foreign matter deposited inside the casing from the change in capacitance, A device for estimating the amount of foreign matter accumulation, equipped with the following features. (2) The casing and a second distance (gap t) smaller than the first distance B (In terms of size, etc.), an auxiliary conductor (such as a sub-conductor member 314B) is disposed inside the casing, An auxiliary measuring device for measuring the capacitance between the casing and the auxiliary conductor, A correction device for correcting the amount of foreign matter accumulation based on the measurement results of the auxiliary measuring device, The foreign matter accumulation amount estimation device according to (1) above, characterized by comprising the above. (3) The correction device determines the saturation of the capacitance measured by the auxiliary measuring device. The foreign matter accumulation amount estimation device according to (2) above, characterized by comprising the above. (4) A communication port (communication port 236, etc.) in the conductive material A foreign matter accumulation amount estimation device according to any one of the above items (1) to (3), characterized by comprising the above. (5) A temperature measuring device (such as a temperature sensor 294) is installed in the casing, A heater (such as heater 290) for heating the casing, Based on the measured value of the temperature measuring device (such as the output of the temperature sensor 294), a control device (such as the temperature control device 292) controls the heater. A foreign matter accumulation amount estimation device according to any one of the above items (1) to (3), characterized by comprising the above. (6) Piping components equipped with a foreign matter accumulation estimation device as described in any one of items (1) to (3) above (e.g., piping components 410, 430, 440).

[0083] <Other> It should be noted that the present invention is not limited to the embodiments described above, and various modifications and combinations of the embodiments are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0084] 210, 310, 380: Foreign matter accumulation amount estimation device 212, 312, 382: Casing 213: Inner surface 214, 364, 384: Conductive material 215: Outer surface 216: Measuring device 218: Arithmetic device 220, 260, 320, 390: Foreign object detection device 224A: First flange section 224B: Second flange section 225A: Entrance 225B:Exit 226: Intermediate flange section 228: Through hole 229: Fixing nut 230: Conductive pin 233: Insulating board 236: Connecting port 238: Fixing screw 240: Spacer 290: Heater 292: Temperature control device 294: Temperature sensor 313: Inner surface 314A: Main conductive component 314B: Subconducting member 315A: Outer surface 315B: Outer surface 330A: Conductive pin 330B: Conductive pin 366: Auxiliary measuring device 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 with 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 deposited inside the casing from the change in capacitance, Equipped with, A foreign matter accumulation estimation device having a conductor having a portion that is arranged along the entire inner surface of the casing and a portion that is partially missing and arranged along a part of the inner surface of the casing, thereby forming a double-tube structure with the casing.

2. An auxiliary conductor disposed inside the casing at a distance smaller than the first distance from the casing, An auxiliary measuring device for measuring the capacitance between the casing and the auxiliary conductor, A correction device for correcting the amount of foreign matter accumulation based on the measurement results of the auxiliary measuring device, The foreign matter accumulation amount estimation device according to claim 1, characterized by comprising the above.

3. The correction device is a saturation determination device that determines the saturation of the capacitance measured by the auxiliary measuring device. The foreign matter accumulation amount estimation device according to claim 2, characterized by comprising the above.

4. Communication opening in the aforementioned conductor A foreign matter accumulation amount estimation device according to any one of claims 1 to 3, characterized by comprising the above.

5. A temperature measuring device is installed in the casing, A heater for heating the casing, Based on the temperature measurement value of the temperature measuring device, a control device controls the heater. A foreign matter accumulation amount estimation device according to any one of claims 1 to 3, characterized by comprising the above.

6. A piping component equipped with a foreign matter accumulation amount estimation device according to any one of claims 1 to 3.

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