Foreign matter deposition amount estimation device and piping component

Abstract

Provided is a foreign matter deposition amount estimation device capable of estimating a deposition amount of foreign matter. Provided are a conductive casing 212 having an inlet 225A and an outlet 225B, a conductor member 214 disposed at an inner side of the casing 212 with a gap t from the casing 212, a measurement device 216 that measures electrostatic capacitance between the casing 212 and the conductor member 214, and an arithmetic device 218 that estimates, from a change in electrostatic capacitance, a foreign matter deposition amount in the casing 212. The conductor member 214 includes a communication port 236.

Description

[DESCRIPTION]FOREIGN MATTER DEPOSITION AMOUNT ESTIMATION DEVICE AND PIPING COMPONENT[Technical Field]

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

[0002] In general, a turbo molecular pump is known as a kind of vacuum pump. This turbo molecular pump is used, for example, for exhaust in a manufacturing device such as a semiconductor or a flat panel. In the turbo molecular pump, a rotor blade is rotated by energization to a motor in a pump main body, and gas molecules (gas molecules) of gas (process gas) sucked into the pump main body are flicked off to discharge the gas. In addition, such a turbo molecular pump includes a type provided with a heater and a cooling pipe in order to appropriately manage the temperature in the pump.

[0003] In a vacuum pump used for exhaust of a device for manufacturing a semiconductor, a flat panel, or the like, a reaction product (foreign matter) generated in a manufacturing process of the semiconductor or the flat panel may be deposited in the vacuum pump or in a pipe connected to the downstream of the vacuum pump. When a large amount of foreign matter is deposited, the flow of gas in the vacuum pump may be disturbed by the foreign matter, or the foreign matter may collide with the rotating portion. For this reason, a technique of detecting a deposition amount of the foreign matter on the basis of a change in electrostatic capacitance has been devised so that a time related to maintenance in a vacuum pump can be determined in advance.

[0004] In the invention disclosed in PTL 1 (paragraphs 0035 to 0039, Fig. 2, etc. ) described later, a change in electrostatic capacitance due to deposits deposited between parallel plate electrodes is measured. In the invention disclosed in PTL 2 (paragraphs 0073 and 0074, Fig. 7, etc. ) , a change in electrostatic capacitance due to deposits on the surface of the comb-shaped electrode is measured.[Citation List][Patent Literature]

[0005] [PTL 1] Japanese Patent Application Publication No. 2018-159632 [PTL 2] Japanese Patent Application Publication No. 2021-195893 [Summary of Invention] [Technical Problem]

[0006] The invention disclosed in PTL 1 has the following problems.(1) Since there is no sufficient installation space, only a small sensor can be installed, and sufficient detection sensitivity cannot be obtained .(2) The sensor blocks the gas flow path, which adversely affects the exhaust performance.(3) It is not easy to extract a sensor signal from the inside of the pump to the outside.

[0007] On the other hand, in the invention disclosed in PTL 2, since the thickness of the sensor is small and the sensor can be installed on the surface of the gas flow path, the gas flow path is not blocked as in the invention disclosed in PTL 1. However, although detection is possible in a situation where the thickness of the deposit is small (thin) , there is a problem that the sensitivity decreases and detection becomes difficult as the thickness increases.

[0008] An object of the present invention is to provide a foreign matter deposition amount estimation device and a piping component capable of estimating a deposition amount of foreign matter.[Solution to Problem]

[0009] In order to achieve the above object, a foreign matter deposition amount estimation device according to the present invention includes : a conductive casing with an inlet and an outlet; a conductor disposed inside the casing at a predetermined first distance from the casing; a measurement device configured to measure electrostatic capacitance between the casing and the conductor; and an arithmetic device configured to estimate a foreign matter deposition amount in the casing from a change in the electrostatic capacitance .In addition, the piping component according to the present invention includes the foreign matter deposition amount estimation device.[Advantageous Effects of Invention]

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

[0011] [Fig. 1]Fig. 1 is an explanatory diagram illustrating a vacuum exhaust system including a piping component according to a first embodiment of the present invention. [Fig. 2]Fig. 2 is an explanatory diagram schematically illustrating a configuration of a foreign matter deposition amount estimation device and a piping component according to the first embodiment of the present invention . [Fig. 3]Fig. 3 is a perspective view illustrating a foreign matter deposition amount estimation device according to a modification in which one communication port of a conductor member is provided. [ Fig . 4 ]Fig. 4 is an explanatory diagram illustrating a foreign matter deposition amount estimation device according to a modification in which temperature control is performed. [Fig. 5]Fig. 5 is an explanatory diagram schematically illustrating a configuration of a foreign matter deposition amount estimation device and a piping component according to a second embodiment. [Fig. 6] Fig. 6 is an explanatory diagram schematically illustrating a configuration of a foreign matter deposition amount estimation device and a piping component according to a third embodiment. [Description of Embodiments]

[0012] <Outline of First Embodiment>Fig. 1 illustrates a vacuum exhaust system 420 provided 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) isformed in the piping component 410. The vacuum exhaust system 420 illustrated in Fig. 1 includes, for example, a processing chamber 422 constituting a manufacturing device for a semiconductor or the like (semiconductor, flat panel, etc. ) , a turbo molecular pump 100, a roughing pump 424, and the like.

[0013] The processing chamber 422 and the turbo molecular pump 100 are connected by a pipe 426 so as to allow gas to flow. The turbo molecular pump 100 and the roughing pump 424 are connected by a pipe 428 so as to allow gas to flow. As the processing chamber 422, the turbo molecular pump 100, and the roughing pump 424, known ones or general ones can be adopted. A pipe for supplying purge gas may be connected to the turbo molecular pump 100. In the vacuum exhaust system 420, a plurality of or a plurality of sets of the processing chambers 422, the turbo molecular pumps 100, and the roughing pumps 424 may be provided.

[0014] The pipes 426 and 428 can be configured by connecting a plurality of piping components. Generally, there are many types of piping components. Specifically, examples of the piping component include a straight pipe having a single pipe shape, an elbow having an elbow curved in an L shape or the like, and a cross crossing in an X shape. Examples of the piping component include a piping component in which a pipe portion is formed in a tapered shape, and a piping component including a valve and various gauges (temperature gauge, pressure gauge, etc. ) . In the present embodiment, a single pipe type (straight type) piping component 410 will be described as an example.

[0015] The piping component 410 is connected to a piping component 428A at the preceding stage and a piping component 428B at the subsequent stage. In the example of Fig. 1, the piping component 428A at the preceding stage is illustrated in an L shape, and the piping component 428B at the subsequent stage is illustrated in a single tube shape. However, the present invention is not limited thereto, and the piping component 428A and the piping component 428B may be disposed in various forms. The piping component 428A at the preceding stage and the piping component 428B at the subsequent stage may be configured by combining a plurality of piping components. Further, it is also possible to connect the piping component 410 to the middle or end of the pipe 426 between the processing chamber 422 and the turbo molecular pump 100.

[0016] Fig. 2 illustrates the piping component 410 in an enlargedmanner. The piping component 410 includes a foreign matter deposition amount estimation device 210. The foreign matter deposition amount estimation device 210 estimates the deposition amount of foreign matter (reaction product) deposited inside the piping component 410. In the examples of Figs. 1 and 2, the deposit is generated by a chemical reaction or a physical change of a component of the exhaust gas from the turbo molecular pump 100 or a component of a mixed gas of the exhaust gas and another gas (purge gas or the like) under conditions such as temperature and pressure in the environment.

[0017] The foreign matter deposition amount estimation device 210 includes a casing 212 and a conductor member 214. Further, the foreign matter deposition amount estimation device 210 includes a measurement device 216 and an arithmetic device 218. In Fig. 2 illustrating the structures of the foreign matter deposition amount estimation device 210 and the piping component 410, hatching indicating a cross section of the component is omitted in order to avoid complication of the drawing.

[0018] Although details will be described later, the casing 212 and the conductor member 214 constitute a foreign matter detection device (foreign matter detection unit) 220. The foreign matter detection device 220 is electrically connected to the measurement device 216, and the generation status of the foreign matter in the foreign matter detection device 220 is measured by the measurement device 216. The measurement result of the measurement device 216 is transmitted to the arithmetic device 218, and the generation status of the foreign matter is determined on the basis of the calculation result of the arithmetic device 218.

[0019] The foreign matter detection device 220 has a double pipe structure including the casing 212 and a conductor member 214, similarly to a foreign matter detection device 260 of a modification illustrated in Fig. 3. The foreign matter detection device 260 of the modification illustrated in Fig. 3 and the foreign matter detection device 220 of Fig. 2 are different in terms of the number of communication ports 236 described later and the like.

[0020] However, here, with respect to the foreign matter detection device 220 illustrated in Fig. 2, points in common with the foreign matter detection device 260 in Fig. 3 will be described with reference to Fig. 3. In Fig. 3 referenced, the casing 212 and the conductor member 214 are shown with different concentrations of shading.

[0021] In the foreign matter detection device 220 illustrated in Figs2, the casing 212 and the conductor member 214 are formed into a cylindrical shape by, for example, processing a conductive material such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. Among these members, the casing 212 is a single tubular member including a cylindrical portion 222, a first flange portion 224A, a second flange 224B, and an intermediate flange portion 226.

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

[0023] Here, the term "casing" is used to mean, for example, a structure having a function of covering at least a part of an internal object (here, the conductor member 214 or the like) . For this reason, a structure in which the inlet 225A and the outlet 225B are opened like the casing 212 is also included in the "casing". Examples of another name of the "casing" include a "tubular structure", a "tubular structure part", a "target", a "target part", a "gas introduction body", a "gas introduction part", an "outer shell body", and an "outer shell part".

[0024] Although not illustrated, the connection between the first flange portion 224A and the piping component 428A at the preceding stage (Fig. 1) and / or the connection between the second flange portion 224B and the piping component 428B at the subsequent stage (Fig. 1) can be performed by, for example, a vacuum pipe clamp with a center ring, which is a kind of vacuum pipe joint, interposed therebetween. The casing 212 and the piping component 428A at the preceding stage (and / or the piping component 428B at the subsequent stage) can be connected by bolting.

[0025] Further, the casing 212 may be connected to the piping component 428A at the preceding stage and the piping component 428B at the subsequent stage by welding without providing the flange portion. In a case where welding is performed, the flange portion (first flange portion 224A and / or second flange portion 224B) on the welded side can beomitted .

[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 thickness of the conductor member 214 is thinner than the thickness of the casing 212. The conductor member 214 is disposed concentrically (coaxially) inside the casing 212. A gap t (Fig. 2) is interposed 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, "interval", "distance", "inter-electrode distance", or the like. The size of the gap t is, for example, about 2 mm.

[0027] The conductor member 214 is supported inside the casing 212 in a state of being suspended by a conductive pin 230. The fixing between the conductive pin 230 and the conductor member 214 can be performed, for example, by screwing a distal end portion of the conductive pin 230 into a coupling hole 232 of the conductor member 214. Here, a portion of the conductor member 214 into which the conductive pin 230 is screwed may be partially formed thick so as to obtain a sufficient contact area (fastening force) .

[0028] The fixing between the conductive pin 230 and the conductor member 214 is not limited to the screwing as long as the conduction between the conductive pin 230 and the conductor member 214 is possible, and can be performed by various methods including press-fitting, for example .

[0029] The conductive pin 230 is formed in a stepped cylindrical shape by, for example, processing a conductive material such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. 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] O-rings 227 are attached to portions of the conductive pin 230 having a relatively small diameter. In the through hole 228, the conductive pin 230 and the casing 212 are airtightly sealed by the 0- rings 227. Therefore, the O-rings 227 exhibit a vacuum sealing function. Further, the conductive pin 230 is fixed to the casing 212 via a fastening force of a fixing nut 229 disposed outside the intermediateflange portion 226.

[0031] The fixing nut 229 is formed using, for example, a conductive material such as stainless steel. A rectangular plate-shaped 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 seat surface of the intermediate flange portion 226 processed to be flat. Although not illustrated, a terminal (round crimp terminal or the like) constituting an end portion of the electric wiring is sandwiched between the fixing nut 229 and the insulating plate 233.

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

[0033] As illustrated in Fig. 2, the conductor member 214 is provided with a plurality of (six in the example of Fig. 2) communication ports 236. The communication ports 236 penetrate the casing 212 in the thickness direction (radial direction) , and are arranged in a line and at equal intervals along the axial direction of the conductor member 214. Further, the opening dimensions of the communication port 236 are common. Here, in the foreign matter detection device 260 according to the modification of Fig. 3, only one communication port 236 is provided, which is different from the foreign matter detection device 220 of Fig. 2 and the foreign matter detection device 260 of Fig. 3.

[0034] In the example of Fig. 2, among the plurality of communication ports 236 arranged in a line, the spacer 240 is inserted into the communication port 236 at the leftmost end (the end portion closest to the inlet 225A) . In Fig. 2, the spacer 240 is hatched for emphasis. An example of this spacer 240 is shown in Fig. 3 incorporated by reference. In the modification of Fig. 3, only one spacer 240 is used, and isinserted into only one communication port 236. In the modification of Fig. 3, the communication port (communication port 236) into which the spacer 240 is not inserted is not provided. Also in these respects, the foreign matter detection device 220 of Fig. 2 is different from the foreign matter detection device 260 of the modification according to Fig. 3.

[0035] As illustrated with reference to Fig. 7, the spacer 240 is formed in a stepped pin shape by, for example, processing an electrically insulating material such as rubber (including other synthetic resins) or ceramics. One end portion of the spacer 240 in the axial direction is formed to be relatively thin and is inserted into the communication port 236.

[0036] The other end portion of the spacer 240 in the axial direction (the end portion on the outer side of the conductor member 214) faces the inner peripheral surface 213 of the casing 212. One end portion of the spacer 240 is interposed between the conductor member 214 and the casing 212 in a state of being in contact with the inner peripheral surface 213 of the casing 212. The spacer 240 prevents the conductor member 214 from rotating (swinging) about the conductive pin 230 as the central axis while ensuring the interval between the conductor member 214 and the casing 212.

[0037] In both the example of Fig. 2 and the modification of Fig. 3, the two spacers 240 are arranged at positions separated by 180 degrees in phase in the circumferential direction of the conductor member 214. Furthermore, three or more spacers 240 (and communication ports 236) may be disposed at intervals of 120 degrees, intervals of 90 degrees, or the like in the circumferential direction. The spacer 240 may be attached to the communication port 236 located at the end portion closest to the outlet 225B. Furthermore, the spacer 240 may be attached to the communication port 236 disposed at a portion in the middle of one line. Further, the spacer 240 may be mounted on the plurality of communication ports 236 in one line.

[0038] <Detection of Electrostatic Capacitance C>The fixing screw 238 (at least a fixing screw to which a wiring is connected) is connected to the casing 212 in an energizable state, and the conductive pin 230 is connected to the conductor member 214 in an energizable state. When a voltage is applied to the casing 212 and theconductor member 214 via the fixing screw 238 and the conductive pin 230, a potential difference is generated between the casing 212 and the conductor member 214. Since the gap t is interposed between the casing 212 and the conductor member 214, the electric charge Q (= CV) corresponding to the potential difference and the electrostatic capacitance is charged between the casing 212 and the conductor member 214.

[0039] C in the above-described Q = CV equation (hereinafter, referred to as "Expression (1)") is an electrostatic capacitance, and V is a potential difference. Then, since the potential difference V is known, the electrostatic capacitance C can be obtained by detecting (measuring) the electric charge Q and performing calculation (C = Q / V) . Furthermore, by obtaining a difference in electrostatic capacitance calculated at different timings, a change (AC) in electrostatic capacitance C within the time can be obtained.

[0040] In addition, the electrostatic capacitance in the case of the parallel plate conductor is obtained by an equation of C = sS / d (hereinafter, referred to as "Expression (2)") . The meanings of the symbols in Expression (2) are as follows.C: Electrostatic Capacitance s: Dielectric Constant of Substance between Conductors (Relative Dielectric Constant)S: Area of Opposed surface of Conductor d: Distance between Conductors

[0041] In the examples of Figs. 2 and 3, the casing 212 and the conductor member 214 have a cylindrical shape arranged concentrically. The electrostatic capacitance between the casing 212 and the conductor member 214 can be expressed by an equation of C = (2ns ) / (in (b / a) )(hereinafter, referred to as "Expression (3)") , which is an equation of the electrostatic capacitance related to the coaxial cylindrical conductor .Here, the meaning of each symbol is as follows.C: Electrostatic Capacitance n: Circumference s: Dielectric Constant of Substance between Conductors (Relative Dielectric Constant) a: Outer Diameter of Conductor Member 214b: Inner Diameter of Casing 212In addition, in is a natural logarithm.

[0042] As described above, the casing 212 and the conductor member 214 are connected to the measurement device 216, and the measurement device 216 is connected to the arithmetic device 218. The casing 212 and the conductor member 214 serve as electrodes and constitute an electrostatic capacitance sensor. In the measurement device 216, the electric charges of the casing 212 and the conductor member 214 are measured, and in the arithmetic device 218, the electrostatic capacitance and the change in electrostatic capacitance related to different timing are calculated on the basis of the measurement result of the measurement device 216. Note that the roles of the measurement device 216 and the arithmetic device 218 are not limited thereto. For example, some calculations may be performed in the measurement device 216, or all calculations may be performed in the arithmetic device 218. In addition, the measurement device 216 and the arithmetic device 218 may be integrated. Furthermore, the arithmetic device 218 may be integrated with a control device of another device (for example, a control device of the turbo molecular pump 100) .

[0043] In the examples of Fig. 1 and Fig. 2, the gas from the turbo molecular pump 100 flows into the foreign matter detection device 220, and the flowing gas flows between the casing 212 and the conductor member214 and inside the conductor member 214. The gas is in contact with both the inner peripheral surface 213 of the casing 212 and the outer peripheral surface 215 of the conductor member 214. Therefore, foreign matters (reaction products) are generated and deposited on both the inner peripheral surface 213 of the casing 212 and the outer peripheral surface215 of the conductor member 214. As the operation time of the turbo molecular pump 100 is cumulatively increased, the amount of foreign matter deposited on the casing 212 and the amount of foreign matter deposited on the conductor member 214 gradually increase.

[0044] As the thickness of the foreign matter increases, the gap t between the casing 212 and the conductor member 214 is gradually filled, and the electrostatic capacitance between the casing 212 and the conductor member 214 increases as the gap t narrows. Then, in the measurement device 216, the electrostatic capacitance is measured, and in the arithmetic device 218, the amount of change or the like related tothe electrostatic capacitance is calculated.

[0045] In the vacuum exhaust system of the example of Fig. 1, the gas from the turbo molecular pump 100 is introduced into the foreign matter detection device 220. Therefore, it can be considered that the change in electrostatic capacitance in the foreign matter detection device 220 is correlated with the accumulation of foreign matter inside the turbo molecular pump 100 and reflects the accumulation situation of foreign matter. Therefore, by monitoring the change in electrostatic capacitance in the foreign matter detection device 220, the foreign matter deposition amount inside the turbo molecular pump 100 can also be estimated.

[0046] <Utilization of Temperature Management>The deposition amount of the foreign matters varies depending on the pressure and temperature of the surrounding environment and the composition of the gas (type of gas) . The foreign matter deposition amount can also be estimated by adjusting the temperature of the piping component 410. For the temperature adjustment, for example, as illustrated in Fig. 4, an annular heater 290 is attached to the outer periphery of the casing 212, and the heater 290 can be controlled by the temperature control device 292 to adjust the temperature in the foreign matter detection device 220.

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

[0048] <Output Destination of Estimation Result>Examples of an output destination of the estimation result (estimated amount of foreign matter) calculated by the arithmetic device 218 and a connection destination of the arithmetic device 218 include various computer devices. Examples of various computer devices include a control device (not illustrated) of the turbo molecular pump 100, a control device (not illustrated) of the processing chamber 422, and an integrated control device owned by a user of the turbo molecular pump 100 or the processing chamber 422. Furthermore, examples of the various computer devices include an inspection terminal device carried by a maintenance worker. Examples of the maintenance worker include a maintenance worker of the turbo molecular pump 100, a maintenance workerof the processing chamber 422, and a maintenance worker of a vacuum exhaust system including these.

[0049] <Typical Merits of Foreign Matter Deposition Amount Estimation Device 210 and Piping Component 410 according to First Embodiment>According to the foreign matter deposition amount estimation device 210 of the first embodiment described above and the piping component 410 including the foreign matter deposition amount estimation device 210, it is possible to estimate the deposition amount of foreign matters generated inside the casing 212 on the basis of a change in electrostatic capacitance inside the casing 212. In other words, it is possible to measure the change in electrostatic capacitance inside the casing 212 and estimate the deposition amount of foreign matters in the measured piping component 410 (and the foreign matter deposition amount estimation device 210 itself) .

[0050] Further, for example, as compared with the invention disclosed in PTL 1 described above, there are few restrictions on the installation space of the sensor (high degree of freedom) . Furthermore, the electrostatic capacitance can be detected using a relatively large space, and it is easy to increase the size of the electrostatic capacitance sensor. Then, it is easy to secure a large area (charged area) of the electrode in the electrostatic capacitance sensor, and it is easy to increase the detection sensitivity. Furthermore, the casing 212 and the conductor member 214 serving as electrodes have a cylindrical shape, and it is easy to secure a large area as compared with a case where the electrodes have a flat plate shape. In addition, since the electrode can be arranged following the pipe shape (or along) , the detection direction of the electrode can be matched with the deposition direction of the foreign matters (for example, the radial direction of the pipe, the direction orthogonal to the axis of the pipe, and the like) , and the deposition amount of the foreign matters deposited in the pipe can be more accurately grasped.

[0051] In addition, since the conductor member 214 has a cylindrical shape and is disposed concentrically in the casing 212, it is possible to suppress the ratio of the electrostatic capacitance sensor to the cross- sectional area of the gas flow path to be small. Therefore, it is possible to prevent the electrostatic capacitance sensor from blocking the gas flow path and adversely affecting the exhaust performance. Thereis no need to route the wires to a gas flow path or a narrow space, and the wires can be easily routed.

[0052] According to the foreign matter detection device 220 (Fig. 1) of the foreign matter deposition amount estimation device 210, the conductor member 214 has the communication port 236 penetrating the conductor member 214 in the thickness direction. Therefore, the gas flowing into the conductor member 214 can be guided to the gap t via the communication port 236. Therefore, the gas can easily enter the gap t, and the fluidity of the gas is good. Furthermore, since the plurality of communication ports 236 are provided along the axial direction of the conductor member 214, the gas can be easily flowed over the entire gap t.

[0053] More specifically, in a case where the communication port 236 is not provided in the conductor member 214, the gas flowing into the conductor member 214 flows to the side of the second flange portion 224B located downstream of the casing 212. Since the conductor member 214 is formed in a cylindrical shape, the inlet of the gas into the gap t is limited to the end portion of the casing 212 on the first flange portion 224A side located on the upstream side.

[0054] As a result, the foreign matter is intensively generated in the vicinity of the inlet to the gap t (the portion on the side of the first flange portion 224A and the inlet 225A) , and is easily accumulated unevenly in the vicinity of the inlet to the gap t (the vicinity of the inlet 225A) . As a result, the vicinity of the inlet to the gap t is filled with the deposit, and the gas hardly flows into the deep portion of the gap t. Further inflow of the gas into the gap t is prevented, and it becomes difficult to spread the gas throughout the gap t.

[0055] However, by providing the communication port 236 in the conductor member 214, the gas can be guided from the inside of the conductor member 214 to the deep portion of the gap t (toward the outlet 225B) via the communication port 236. Then, the gas can easily enter the entire gap t, and the fluidity of the gas can be improved. As a result, it is possible to prevent foreign matter from being unevenly accumulated in the vicinity of the inlet of the gap t (the vicinity of the inlet 225A) . Then, the electrostatic capacitance between the casing 212 and the conductor member 214 can be measured more accurately.

[0056] In addition, since the plurality of communication ports 236 are provided along the axial direction of the conductor member 214, the gascan be easily flowed over the entire gap t. This also makes it possible to more accurately measure the electrostatic capacitance between the casing 212 and the conductor member 214. Here, the arrangement of the plurality of communication ports 236 is not limited to one row, and may be a plurality of rows, staggered arrangement, or the like. In addition, the conductor member 214 may be formed using a punching metal or the like having a large number of holes.

[0057] In order to enhance the fluidity of the gas, for example, the conductor member 214 may be formed to have a semicircular (semi- cylindrical shape, arcuate shape) cross section to open a part of the side surface (peripheral surface) of the conductor member 214. However, also in this case, there is a possibility that foreign matter is unevenly deposited in the vicinity of the inlet of the gap t between the conductor member 214 having a semicircular (semi-cylindrical shape, arcuate shape) cross section and the casing 212. Therefore, providing the plurality of communication ports 236 in the conductor member 214 along the axial direction makes it easier to guide the gas to the entire gap t. In a case where the conductor member 214 has a semicircular shape (semi-cylindrical shape, arcuate shape) or another shape, the conductor member 214 may be formed using a punching metal or the like having a large number of holes.

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

[0059] Fig. 5 illustrates a foreign matter detection device 320 of a foreign matter deposition amount estimation device 310 according to the second embodiment and a piping component 430 including the same together with the measurement device 216 and the arithmetic device 218. In the example of Fig. 5, the foreign matter detection device 320 includes two conductor members (a main conductor member 314A and a sub-conductor member 314B) . Although details will be described later, the sub-conductor member 314B functions as an auxiliary conductor.

[0060] The main conductor member 314A and the sub-conductor member 314B are both formed in a cylindrical shape, and are arranged inside a casing 312 in a row along the axial direction of the casing 312. The mainconductor member 314A is disposed on the second flange portion 224B side, and the sub-conductor member 314B is disposed on the first flange portion 224A side. Further, the main conductor member 314A and the sub-conductor member 314B are disposed concentrically with the casing 312.

[0061] An end portion 372 of the main conductor member 314A and an end portion 374 of the sub-conductor member 314B are processed perpendicular (perpendicular) to the axial center 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 in a state of being supported by the conductive pin 330A. Here, as the conductive pin 330A, one similar to the conductive pin 230 in the first embodiment can be adopted. In addition, the main conductor member 314A can be fixed to the conductive pin 330A in a similar manner to the fixing of the conductor member 214 to the conductive pin 230 in the first embodiment by a method such as screwing.

[0063] The sub-conductor member 314B is fixed to the conductive pin 330B, and is supported inside the casing 312 in a state of being suspended by the conductive pin 330B. Here, as the conductive pin 330B, one similar to the conductive pin 230 (and the conductive pin 330A of the main conductor member 314A) in the first embodiment can be adopted. In addition, the sub-conductor member 314B can be fixed to the conductive pin 330B in a similar manner to the fixing of the conductor member 214 to the conductive pin 230 in the first embodiment by a method such as screwing .

[0064] A gap tA (inter-electrode distance, Fig. 5) is interposed between an outer peripheral surface 315A of the main conductor member 314A and an inner peripheral surface 313 of the casing 312. The size of the gap tA is a similar value (for example, 2 mm) to the gap t of the first embodiment.

[0065] A gap tB (inter-electrode distance, Fig. 5) is interposed between an outer peripheral surface 315B of the sub-conductor member 314B and the inner peripheral surface 313 of the casing 312. 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, the size of the gap tB is smaller than the gap tA related to the main conductor member 314A (tA > tB) . The size of the gap tB can be, for example, less than 2 mm (0.5 to 1.9 mm, preferably 0.8 to 1.6 mm, more preferably 1 mmto 1.4 mm) .

[0066] As described above, by providing the sub-conductor member 314B having a different inter-electrode distance from the main conductor member 314A in the casing 312, it is possible to arrange, in a common environment, two (a plurality of) electrostatic capacitance sensors having different timings at which the electrostatic capacitance saturates first in one (a part) . The electrostatic capacitance sensor is formed by a combination of the main conductor member 314A and the casing 312 and a 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, by forming the gaps tA and tB having different sizes under a common environment, the gap tB on the small side is filled with foreign matter earlier than the gap tA on the large side, and the electrostatic capacitance C is saturated. For this reason, it is possible to form an electrostatic capacitance sensor with slow saturation (the main conductor member 314A side) and an electrostatic capacitance sensor with fast saturation (the sub-conductor member 314B side) . 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 electrostatic capacitance sensor on the side where the gap tB is narrow (the sub-conductor member 314B side) , the gap tB is filled with the foreign matter earlier than the electrostatic capacitance sensor on the side where the gap tA is wide (the main conductor member 314A side) , and the electrostatic capacitance is saturated. At this time, even in the gap tA on the wide side, it is considered that foreign matter is deposited with a thickness similar to that of the gap tB on the narrow side, and the size of the gap tB on the narrow side is known, so that the thickness of the deposit in the gap tA on the wide side can be estimated.

[0069] Further, thereafter, the dielectric constant (relative dielectric constant) e of the foreign matter can be calculated from theabove-described Expression (2) related to the electrostatic capacitance of the parallel plate conductor and Expression (3) related to the electrostatic capacitance of the coaxial cylindrical conductor. In addition, it is also possible to estimate the type of the foreign matter on the basis of the calculated value of the dielectric constant. In addition, the amount of foreign matter inside the piping component 410 can be estimated using an electrostatic capacitance sensor (the main conductor member 314A side) on the side where the gap tA is wide.

[0070] In the example of Fig. 5, an auxiliary measurement device 366 is provided as a measurement device related to the sub-conductor member 314B. Similarly to the measurement device 216 related to the main conductor member 314A, the auxiliary measurement device 366 has a function of measuring electric charges of the casing 312 and the subconductor member 314B. Furthermore, a correction device 367 is connected to the auxiliary measurement device 366. The correction device 367 has a function of determining saturation of electrostatic capacitance as described above on the basis of the output of the auxiliary measurement device 366. Further, the correction device 367 has a function of correcting the foreign matter deposition amount calculated by the arithmetic device 218 related to the main conductor member 314A.

[0071] The auxiliary measurement 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 turbo molecular pump 100) . In addition, the measurement device 216 and the auxiliary measurement device 366 may be integrated, or the arithmetic device 218 and the correction device 367 may be integrated. Further, the measurement device 216, the arithmetic device 218, the auxiliary measurement device 366, and the correction device 367 may be integrated.

[0072] In the second embodiment, the main conductor member 314A is disposed on the first flange portion 224A side located on the upstream side, and the sub-conductor member 314B is located on the second flange portion 224B side located on the downstream side, but the present invention is not limited thereto. For example, the main conductor member 314A may be disposed on the downstream side (the second flange portion 224B side) , and the sub-conductor member 314B may be disposed on the upstream side (the first flange portion 224A side) .

[0073] In the second embodiment, the end portions 372 and 374 of the main conductor member 314A and the sub-conductor member 314B facing each other are processed at a right angle (perpendicular) with respect to the axial direction, but the present invention is not limited thereto. Although not illustrated, for example, the end portions 372 and 374 of the main conductor member 314A and the sub-conductor member 314B facing each other may be processed obliquely with respect to the axial direction so as to face each other. In addition, the main conductor member 314A and the sub-conductor member 314B may be processed into semicircular shapes so as to face each other in the vertical direction of Fig. 10.

[0074] In the example of Fig. 5 according to the second embodiment, the spacer 240 is attached to the communication port 236 closest to the inlet 225A in the main conductor member 314A and the communication port 236 closest to the outlet 225B in the sub-conductor member 314B. However, the present invention is not limited thereto, and the spacer 240 may be mounted on any communication port 236. Furthermore, the spacer 240 may be attached to the plurality of communication ports 236 in the main conductor member 314A and ( / or) the sub-conductor member 314B. In Fig. 5, the spacer 240 is hatched for emphasis.

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

[0076] Fig. 6 illustrates a foreign matter detection device 390 of the foreign matter deposition amount estimation device 380 according to the third embodiment and a piping component 440 including the same together with the measurement device 216 and the arithmetic device 218. In the example of Fig. 6, a structure similar to that of the first embodiment (Fig. 2) is adopted. However, the axial length of a conductor member 384 is set to be larger than the axial length of a casing 382. Both axial end portions of a conductor member 364 jumps out (protrude) from the casing 382 in the axial direction. In the casing 382 of the example of Fig. 6, the axial length is set to be shorter than that of the casing 212 of 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 component 440 can cause the conductor member 384 to reach the inside of the piping components (for example, piping components 428A and 428B in Fig. 1) connected in the front-rear direction. As the axial length of the conductor member 384 increases, the area of the opposed surface with the piping components of the front and rear connection partners increases.

[0078] The piping component to be connected is usually made of metal, and the piping component 440 and the piping component to be connected are usually brought into contact (metal contact) with each other. In addition, in any of the case of interposing the center ring of the standardized vacuum pipe joint, the case of using the vacuum pipe clamp, the case of bolting, and the case of welding, a metal contact portion usually occurs. Therefore, the piping component 440 and the piping component to be connected are electrically conducted, and the foreign matter detection device 390 in which the piping component to be connected is used as the casing can be formed.

[0079] According to the foreign matter deposition amount estimation device 380 and the piping component 440 of the third embodiment, it is possible to increase the area of the electrode using another adjacent piping component. Then, the detection sensitivity of the electrostatic capacitance can be enhanced. Furthermore, it is possible to increase the detection sensitivity of the electrostatic capacitance at a low cost as compared with a case where the foreign matter deposition amount estimation device 380 (and the piping component 440) is enlarged or a case where the plurality of foreign matter deposition amount estimation devices 380 (and the piping components 440) is connected in series along the axial direction.

[0080] In a case where the foreign matter deposition amount estimation device 380 (and the piping component 440) is enlarged, it may be difficult to dispose the foreign matter deposition amount estimation device in a limited installation space, and it is not easy to handle the foreign matter deposition amount estimation device. The cost for installing the foreign matter deposition amount estimation device 380 (and the piping component 440) also increases. However, by utilizing the piping component to be connected, it is not necessary to increase the size of the foreign matter deposition amount estimation device 380 (andthe piping component 440) , and the degree of freedom of handling increases. It is possible to prevent an increase in cost for installing the foreign matter deposition amount estimation device 380 (and the piping component 440) .

[0081] Note that the conductor member 384 may be caused to jump out (protrude) from the casing 212 only at one end portion in the axial direction of the foreign matter deposition amount estimation device 380 and the piping component 440. In addition, as in the third embodiment, even in a case where the conductor member 384 is jumped out from the casing 382, at least a part of the conductor member 384 is present inside the casing 382. Therefore, it can be said that the conductor member 384 is disposed inside the casing 382.

[0082] <Invention Extractable from Embodiments>The following inventions can be extracted from the embodiments described above.(1) A foreign matter deposition amount estimation device including: a conductive casing (casing 212, etc. ) having an inlet (inlet 225A, etc. ) and an outlet (outlet 225B, etc. ) ; a conductor (conductor members 214, 364, and 384, main conductor member 314A, etc. ) disposed at an inner side of the casing at a predetermined first distance (sizes of gaps t and tA, etc. ) from the casing; a measurement device (measurement device 216, etc. ) configured to measure electrostatic capacitance between the casing and the conductor; and an arithmetic device (an arithmetic device 218, etc. ) configured to estimate, from a change in the electrostatic capacitance, a foreign matter deposition amount in the casing.(2) The foreign matter deposition amount estimation device according to (1) , further including: an auxiliary conductor (sub-conductor member 314B, etc. ) disposed at an inner side of the casing at a second distance (size of gap tB, etc. ) , which is smaller than the first distance, from the casing; an auxiliary measurement device configured to measure electrostatic capacitance between the casing and the auxiliary conductor; and a correction device configured to correct the foreign matter deposition amount on a basis of a measurement result of the auxiliarymeasurement device.(3) The foreign matter deposition amount estimation device according to ( 2 ) , in which the correction device includes a saturation determination device configured to determine saturation of the electrostatic capacitance measured by the auxiliary measurement device.(4) The foreign matter deposition amount estimation device according to any one of (1) to (3) , in which the conductor includes a communication port (communication port 236, etc . ) .(5) The foreign matter deposition amount estimation device according to any one of (1) to (3) , including: a temperature measurement device (temperature sensor 294, etc. ) disposed in the casing; a heater (heater 290, etc. ) configured to heat the casing; and a control device (temperature control device 292, etc. ) configured to control the heater on a basis of a measurement value (output of temperature sensor 294, etc. ) of the temperature measurement device.(6) A piping component (piping components 410, 430, and 440, etc. ) including the foreign matter deposition amount estimation device according to any one of (1) to (3) .

[0083] <Others>Note that the present invention is not limited to the abovedescribed embodiments, and various modifications and combinations of the embodiments can be made without departing from the gist. [Reference Signs List]

[0084] 210, 310, 380 Foreign matter deposition amount estimation device 212, 312, 382 Casing 213 Inner peripheral surface 214, 364, 384 Conductor member215 Outer peripheral surface216 Measurement device 218 Arithmetic device220, 260, 320, 390 Foreign matter detection device 224A First flange portion 224B Second flange portion25A Inlet 25B Outlet 2 6 Intermediate f lange portion 28 Through hole 29 Fixing nut 30 Conductive pin 33 Insulating plate 36 Communication port 38 Fixing screw 40 Spacer290 Heater292 Temperature control device294 Temperature sensor313 Inner peripheral surface314A Main conductor member314B Sub-conductor member315A Outer peripheral surface315B Outer peripheral surface330A Conductive pin330B Conductive pin366 Auxil iary measurement device367 Correction device372 End portion374 End portion410 , 430 , 440 Piping component42 6 , 428 Pipe428A, 428B Piping component t Gap tA Gap tB Gap

Claims

[CLAIMS]

1. A foreign matter deposition amount estimation device comprising: a conductive casing having an inlet and an outlet; a conductor disposed at an inner side of the casing at a predetermined first distance from the casing; a measurement device configured to measure, from a change in the electrostatic capacitance, electrostatic capacitance between the casing and the conductor; and an arithmetic device configured to estimate a foreign matter deposition amount in the casing.

2. The foreign matter deposition amount estimation device according to claim 1, further comprising: an auxiliary conductor disposed at an inner side of the casing at a second distance, which is smaller than the first distance, from the casing; an auxiliary measurement device configured to measure electrostatic capacitance between the casing and the auxiliary conductor; and a correction device configured to correct the foreign matter deposition amount on a basis of a measurement result of the auxiliary measurement device.

3. The foreign matter deposition amount estimation device according to claim 2, wherein the correction device includes a saturation determination device configured to determine saturation of the electrostatic capacitance measured by the auxiliary measurement device.

4. The foreign matter deposition amount estimation device according to any one of claims 1 to 3, wherein the conductor includes a communication port.

5. The foreign matter deposition amount estimation device according to any one of claims 1 to 3, comprising: a temperature measurement device disposed in the casing; a heater configured to heat the casing; anda control device configured to control the heater on a basis of a measurement value of the temperature measurement device.

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

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