Fine bubble generator, processing liquid supply device, and substrate processing device

Abstract

This technology provides a way to stabilize the fine bubble generation efficiency even when the liquid flow rate fluctuates. [Solution] The fine bubble generator (1) comprises a first pipe section (21), a second pipe section (23) located downstream of the first pipe section (21), a constricted pipe section (24) located between the first pipe section (21) and the second pipe section (23) and having a portion in which the flow path cross-sectional area decreases toward the downstream, and a variable mechanism (27) that changes the flow path cross-sectional area in the constricted pipe section (24) according to the flow rate of the first pipe section (21).

Description

Technical Field

[0001] The subject matter disclosed in this specification relates to a fine bubble generator, a processing liquid supply device, and a substrate processing device.

Background Art

[0002] Conventionally, a generator for generating fine bubbles has been known. For example, in the device of Patent Document 1, a narrow gap and a gradually expanding region are continuously provided in a flow path through which a liquid flows. In this device, the flow rate is increased by restricting the flow of the liquid in the narrow gap, and a pressure lower than that in the low-speed part of the liquid flow is generated. Then, by releasing the pressure of the liquid flow in the gradually expanding region immediately after the narrow gap, fine bubbles on the micro or nano order are generated from the bubbles mixed in the water. Further, Patent Document 1 also describes that the bubble size can be changed by further narrowing the interval of the narrow gaps.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional fine bubble generator, when the flow rate of the liquid fluctuates, the generation efficiency of the fine bubbles decreases due to changes in the flow velocity and the pressure applied to the liquid. Therefore, it has been difficult to stably generate fine bubbles of a desired size or amount.

[0005] An object of the present invention is to provide a technique capable of stabilizing the generation efficiency of fine bubbles even when the flow rate of the liquid fluctuates.

Means for Solving the Problems

[0006] To solve the above problems, the first embodiment is a fine bubble generator comprising: a first pipe section; a second pipe section located downstream of the first pipe section; a constricted pipe section located between the first pipe section and the second pipe section and having a portion in which the flow path cross-sectional area decreases toward the downstream direction; and a variable mechanism that changes the flow path cross-sectional area in the constricted pipe section according to the flow rate of the first pipe section.

[0007] A second embodiment is a fine bubble generator according to the first embodiment, further comprising a valve housing located between a first pipe section and a second pipe section, to which the first pipe section is connected, wherein the variable mechanism comprises a movable valve body disposed inside the valve housing, and a reciprocating drive unit that moves the valve body forward and backward relative to the constricted pipe section according to the flow rate of the first pipe section.

[0008] The third embodiment is a fine bubble generator according to the second embodiment, wherein the forward and backward drive unit is connected to the valve body and includes a diaphragm that deforms to move the valve body according to the flow rate of the first pipe section, and a biasing unit that biases the valve body connected to the diaphragm toward the constricted pipe section.

[0009] A fourth embodiment is a fine bubble generator according to the third embodiment, further comprising a branch pipe section that branches off in the middle of the first pipe section and is connected to the valve housing, wherein the branch pipe section is connected to the valve housing closer to the diaphragm than the first pipe section.

[0010] The fifth embodiment is a fine bubble generator according to the second embodiment, wherein the forward and backward drive unit further includes a guide unit that guides the movement of the valve body.

[0011] The sixth aspect is a fine bubble generator according to the third aspect, wherein the valve body has a shaft portion connected to the diaphragm, and the reciprocating drive unit further has a bearing portion that movably supports the shaft portion relative to the constricted pipe portion.

[0012] The seventh embodiment is a fine bubble generator according to the second embodiment, wherein the valve housing has an inlet located at a position radially offset with respect to the central axis, and the first pipe section is connected to the inlet.

[0013] The eighth embodiment is a fine bubble generator according to the second embodiment, wherein the valve body is inserted into the portion of the constricted pipe section where the flow path cross-sectional area increases towards the downstream side, and the reciprocating drive unit is located downstream of the constricted pipe section.

[0014] The ninth embodiment is a fine bubble generator according to the first or second embodiment, wherein the constricted tube section has a cylindrical tank and a cylindrical body disposed within the cylindrical tank, and the variable mechanism has a support plate attached to the upper surface of the cylindrical body and movable up and down inside the cylindrical tank, and a second biasing part that biases the support plate upward.

[0015] The tenth embodiment is a processing liquid supply device comprising a fine bubble generator according to the first or second embodiment, and a supply unit that supplies a processing liquid containing fine bubbles generated by the fine bubble generator to an object to be processed.

[0016] The eleventh embodiment is a substrate processing apparatus comprising: a support section for supporting a substrate; a fine bubble generator according to the first or second embodiment; and a supply section for supplying a processing liquid containing fine bubbles generated by the fine bubble generator to the substrate supported by the support section. [Effects of the Invention]

[0017] According to the first to eleventh embodiments, the flow path cross-sectional area of ​​the narrowed pipe section is changed according to the flow rate of the first pipe section, so that the fine bubble generation efficiency can be stabilized even when the liquid flow rate fluctuates.

[0018] According to the fine bubble generator of the second embodiment, the flow path cross-sectional area of ​​the constricted pipe can be easily changed by moving the valve body forward and backward relative to the constricted pipe.

[0019] According to the fine bubble generator of the third aspect, the valve body can be moved by the deformation of the diaphragm. Further, the biasing portion can bias the valve body moved from the specified position so as to return to the specified position.

[0020] According to the fine bubble generator of the fourth aspect, the diaphragm can be deformed by the liquid flowing in from the branch pipe portion.

[0021] According to the fine bubble generator of the fifth aspect, vibrations and rattling during the movement of the valve body can be reduced.

[0022] According to the fine bubble generator of the sixth aspect, vibrations and rattling during the movement of the valve body can be reduced.

[0023] According to the fine bubble generator of the seventh aspect, the liquid can be swirled in the valve housing.

[0024] According to the fine bubble generator of the ninth aspect, the flow path cross-sectional area of the narrow flow path is changed by the support plate moving up and down according to the flow rate. Therefore, even when the flow rate fluctuates, the generation efficiency of the fine bubbles can be stabilized.

Brief Description of Drawings

[0025] [Figure 1] It is a diagram showing a cleaning device provided with a fine bubble generator according to the first embodiment. [Figure 2] It is a diagram showing the configuration of a fine bubble generator according to the first embodiment. [Figure 3] It is a schematic cross-sectional view of the fine bubble generator at the position of the A-A line shown in FIG. 2. [Figure 4] It is a diagram showing a fine bubble generator when the flow rate of the first pipe portion increases. [Figure 5] It is a cross-sectional view showing a fine bubble generator according to the second embodiment. [Figure 6] It is a cross-sectional view of a fine bubble generator according to the third embodiment. [Figure 7A] This is a perspective view showing a fine bubble generator according to the fourth embodiment. [Figure 7B] Figure 7A is a schematic cross-sectional view of the fine bubble generator at the BB line position shown. [Figure 7C] Figure 7A is a schematic cross-sectional view of the fine bubble generator at the CC line position shown. [Figure 7D] Figure 7A is a schematic cross-sectional view of the fine bubble generator at the DD line position shown. [Figure 8] This is a schematic cross-sectional view showing a fine bubble generator according to the fifth embodiment. [Figure 9] This is a schematic cross-sectional view showing a fine bubble generator according to the sixth embodiment. [Figure 10] This is a schematic cross-sectional view showing a fine bubble generator according to the seventh embodiment. [Figure 11] This is a schematic cross-sectional view showing a fine bubble generator according to the eighth embodiment. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below with reference to the attached drawings. In the drawings, the dimensions and number of parts may be exaggerated or simplified.

[0027] <1. First Embodiment> Figure 1 shows a cleaning apparatus 100 equipped with a fine bubble generator 1 according to the first embodiment. The cleaning apparatus 100 is a device for cleaning a substrate W with cleaning water. The substrate W is supported by, for example, a transport roller (not shown) and moves continuously in one direction horizontally by the transport roller. The transport roller corresponds to a support part that supports the substrate.

[0028] The cleaning device 100 includes a supply unit 10. The supply unit 10 includes a high-pressure nozzle 11, a supply pipe 13, a pump 15, a tank 17, and a control unit 19. The high-pressure nozzle 11 has a spray pipe 111 and a plurality of nozzle sections 113. The spray pipe 111 extends in a direction perpendicular to the transport direction of the substrate W. Cleaning water is supplied to the spray pipe 111. The plurality of nozzle sections 113 are arranged at equal intervals along the spray pipe 111. Each nozzle section 113 is designed to spray the cleaning water supplied from the spray pipe 111 at high pressure while dispersing it.

[0029] The supply pipe 13 supplies cleaning water to the high-pressure nozzle 11. The supply pipe 13 connects the tank 17 to the spray pipe 111 of the high-pressure nozzle 11, and the pump 15 supplies cleaning water to the high-pressure nozzle 11. The tank 17 stores the cleaning water supplied to the supply pipe 13. Alternatively, the cleaning water used to clean the substrate W may be collected in the tank 17, thereby circulating the cleaning water.

[0030] The fine bubble generator 1 is positioned, for example, in the middle of the supply piping 13. The fine bubble generator 1 is capable of generating fine bubbles with a diameter of less than 100 μm (micrometers), and in particular, it is capable of generating ultrafine bubbles. Among fine bubbles, bubbles with a diameter of less than 100 μm and 1 μm or more are called microbubbles, and bubbles with a diameter of less than 1 μm are called ultrafine bubbles. Fine bubbles are more stable than ordinary bubbles and can remain in liquid for a long time. Of the fine bubbles, ultrafine bubbles are considered particularly useful in cleaning effects and other applications.

[0031] As shown in Figure 1, the cleaning water containing fine bubbles generated in the fine bubble generator 1 is sent to the high-pressure nozzle 11 through the supply pipe 13. Then, the cleaning water containing fine bubbles is supplied to the substrate W from each nozzle section 113 of the high-pressure nozzle 11. As a result, the substrate W can be cleaned with cleaning water containing fine bubbles, thus achieving a high cleaning effect. In addition, the amount of cleaning water consumed can be reduced, thereby reducing the environmental impact.

[0032] It is not mandatory for the fine bubble generator 1 to be installed in the supply piping 13. For example, the fine bubble generator 1 may be installed in piping for supplying the treated liquid to the tank 17.

[0033] The supply unit 10 supplies a processing liquid (washing water) containing fine bubbles generated by the fine bubble generator 1 to the object to be processed (substrate W). The apparatus comprising the fine bubble generator 1 and the supply unit 10 corresponds to a "processing liquid supply apparatus". Furthermore, the washing apparatus 100 comprising a support unit (transport roller) for supporting the substrate, the fine bubble generator 1, and the supply unit 10 corresponds to a "substrate processing apparatus".

[0034] <Fine bubble generator> Figure 2 shows the configuration of the fine bubble generator 1 according to the first embodiment. The white block arrows shown in Figure 2 and subsequent figures indicate the direction of liquid flow. As shown in Figure 2, the fine bubble generator 1 comprises a first pipe section 21, a second pipe section 23, a constricted pipe section 24, a valve housing 25, and a variable mechanism 27. The first pipe section 21 is located at the upstream end of the fine bubble generator 1. The second pipe section 23 is located downstream of the first pipe section 21. The upstream side of the first pipe section 21 is connected to a supply pipe 13 in a cleaning device 100, for example. The downstream side of the second pipe section 23 is also connected to a supply pipe 13, for example. The constricted pipe section 24 is located between the first pipe section 21 and the second pipe section 23. The downstream side of the constricted pipe section 24 is connected to the second pipe section 23. The upstream side of the constricted pipe section 24 is connected to the first pipe section 21 via a valve housing 25. The inner diameter of the constricted pipe section 24 gradually decreases towards the downstream side, and then increases again. The valve housing 25 connects the first pipe section 21 and the constricted pipe section 24. The first pipe section 21 is connected to an inlet P1 provided in the valve housing 25.

[0035] The valve housing 25, the constricted pipe section 24, and the second pipe section 23 are arranged coaxially with respect to axis A1. In the following description, the direction parallel to axis A1 is referred to as the "axial direction." In the axial direction, the direction from the constricted pipe section 24 toward the second flow path 23 is referred to as "one axial direction," and the opposite direction is referred to as "the other axial direction." The direction perpendicular to axis A1 is referred to as the "radial direction." In the radial direction, the direction approaching axis A1 is referred to as "radial inward," and the direction moving away from axis A1 is referred to as "radial outward." The direction of rotation around axis A1 is referred to as the "circumferential direction."

[0036] The constricted pipe section 24 is connected to the flow path at one axial end of the valve housing 25. The inner diameter (inner width) of the second pipe section 23 is greater than the minimum value of the inner diameter (inner width) of the constricted pipe section 24. Also, the inner diameter (inner width) of the second pipe section 23 is greater than the inner diameter (inner width) of the first pipe section 21.

[0037] At the inlet side of the constricted pipe section 24, the flow velocity of the liquid increases as the cross-sectional area of ​​the flow path decreases. As the flow velocity increases, the pressure on the liquid decreases according to Bernoulli's principle. Therefore, the liquid pressure drops sharply in the constricted pipe section 24. When the pressure drops, gases (such as air) dissolved in the liquid precipitate as bubbles (cavitation). In the constricted pipe section 24, this pressure drop generates a large number of tiny bubbles.

[0038] Furthermore, at the outlet side of the constricted pipe section 24, the flow path cross-sectional area increases again, reducing the liquid flow velocity and returning the liquid pressure to its original level. This return of pressure causes the bubbles generated in the constricted pipe section 24 to shrink. In other words, the diameter of the bubbles becomes very small. As a result, fine bubbles with a diameter of 1 μm or less are formed.

[0039] Although not shown in the diagram, a pipe (not shown) for supplying gas to the liquid may be provided at or upstream of the constricted pipe section 24. By supplying gas to the liquid in the pipe, the amount of fine bubbles generated can be increased.

[0040] The variable mechanism 27 is located within the valve housing 25. The variable mechanism 27 changes the flow path cross-sectional area in the narrowed pipe section 24 according to the flow rate of the liquid in the first pipe section 21. The variable mechanism 27 includes a valve body 31 and a reciprocating drive unit 33.

[0041] The valve body 31 is located inside the valve housing 25. The valve body 31 is a movable member that can move relative to the constricted pipe section 24. The valve body 31 is positioned on axis A1. The valve body 31 has a head 310 which is the main body, and a shaft portion 311 that extends along axis A1 from the end of the head 310. The outer circumferential surface of the head 310 is tapered in one direction toward the axial direction. When the outer circumferential surface of the head 310 approaches the constricted pipe section 24, the flow path cross-sectional area of ​​the constricted pipe section 24 decreases. Conversely, when the outer circumferential surface of the head 310 moves away from the constricted pipe section 24, the flow path cross-sectional area of ​​the constricted pipe section 24 increases.

[0042] The forward / backward drive unit 33 moves the valve body 31 forward and backward relative to the constricted pipe section 24 according to the flow rate of the liquid in the first pipe section 21. The forward / backward drive unit 33 has a diaphragm 331 and a biasing unit 332. The diaphragm 331 and the biasing unit 332 are located on the other axial side relative to the valve body 31.

[0043] The diaphragm 331 deforms to move the valve body 31 in accordance with the flow rate of the liquid flowing from the first pipe section 21 into the valve housing 25. Specifically, the valve housing 25 has a widened section 252. The inner diameter (inner width) of the widened section 252 is larger than the inner diameter (inner width) of the portion of the valve housing 25 in which the valve body 31 is housed. Also, the widened section 252 is located axially away from the inlet P1. The circumferential end of the diaphragm 331 is fixed to the inner circumferential surface of the widened section 252, and the diaphragm 331 is deformable axially within the widened section 252. The end of the shaft section 311 of the valve body 31 is fixed to the diaphragm 331.

[0044] The biasing part 332 is a component for biasing the valve body 31 toward the constricted pipe section 24. If the valve body 31 moves axially to the other side from a specified position, the biasing part 332 presses the valve body 31 back to the specified position. The biasing part 332 is an elastic body, such as a coil spring, which is arranged to expand and contract axially. The biasing part 332 is located axially to the other side of the diaphragm 331. One axial end of the biasing part 332 is fixed to the diaphragm 331. That is, the biasing part 332 biases the valve body 31 via the diaphragm 331.

[0045] The other axial end of the biasing portion 332 is fixed to an adjustment screw 253. The adjustment screw 253 is attached to the other axial end of the valve housing 25. The screw groove of the adjustment screw 253 engages with a screw hole provided in the valve housing 25, and by rotating the adjustment screw 253 around axis A1, the adjustment screw 253 moves in the axial direction. By adjusting the position of the adjustment screw 253, the positions of the biasing portion 332 and the diaphragm 331 are adjusted. This makes it possible to adjust the position of the valve body 31 in the axial direction.

[0046] The forward / backward drive unit 33 has a guide unit 333. The guide unit 333 has a flange unit 41 and a guide ring 43. The flange unit 41 is formed in the shape of a circular plate that extends radially from the shaft unit 311. The guide ring 43 is fixed to the periphery of the flange unit 41 and is formed in the shape of an annular ring (in this case, a circular ring) that protrudes in one axial direction from the periphery of the flange unit 41. The guide ring 43 slides on the inner circumferential surface of the valve housing 25. As a result, the valve body 31 is supported on the shaft A1 and vibration and rattle during the movement of the valve body 31 can be suppressed.

[0047] The forward / backward drive unit 33 has a bearing unit 334. The bearing unit 334 supports the shaft 311 of the valve body 31 so that it can move axially relative to the constricted pipe 24. The bearing unit 334 has a cylindrical portion fixed to the valve housing 25, through which the shaft 311 passes. By moving axially while being supported by the bearing unit 334, vibration and rattle of the valve body 31 can be suppressed.

[0048] Figure 3 is a schematic cross-sectional view of the fine bubble generator 1 at the position indicated by line AA in Figure 2. As shown in Figure 3, the inlet P1 is positioned laterally (radially) offset from axis A1 (the central axis of the valve housing). That is, the first pipe section 21 is connected to the valve housing 25 in a flow path at a position radially offset from the central axis. Therefore, the liquid flowing from the first pipe section 21 into the valve housing 25 moves downstream on one side of the axial direction while swirling in a spiral. By swirling the liquid in this way, centrifugal force is generated, creating pressure differences and allowing the gaseous components to concentrate in the center of the swirl (axis A1), thus enabling efficient generation of fine bubbles in the constricted pipe section 24.

[0049] The fine bubble generator 1 is equipped with a branch pipe section 29. The branch pipe section 29 is a pipe that branches off from the first pipe section 21 and is flow-connected to the valve housing 25. With respect to the valve housing 25, the branch pipe section 29 is flow-connected closer to the diaphragm 331 than the first pipe section 21. More specifically, the downstream end of the branch pipe section 29 is provided at an inlet P2 located in the widened section 252. The inlet P2 is located further axially from the narrowed pipe section 24 than the inlet P1. The inlet P2 is also located further axially from the diaphragm 331 on one side (i.e., the side closer to the narrowed pipe section 24). Furthermore, the inlet P2 is located on the other axial side from the guide ring 43 and the guide section 333 or the bearing section 334. Liquid flows into the space partitioned by the diaphragm 331 in the widened section 252 from the branch pipe section 29 via the inlet P2.

[0050] Figure 4 shows the fine bubble generator 1 when the flow rate in the first pipe section 21 increases. When the liquid flow rate in the first pipe section 21 increases, as shown in Figure 4, the amount of liquid trying to flow from the branch pipe section 29 into the widened section 252 of the valve housing 25 increases, causing the water pressure in the widened section 252 to rise. As a result, the diaphragm 331 deforms in the direction away from the constricted pipe section 24 (the other axial direction), causing the valve body 31 to move away from the constricted pipe section 24. This increases the gap d between the constricted pipe section 24 and the valve body 31. In other words, the flow path cross-sectional area in the constricted pipe section 24 increases in proportion to the increase in the flow rate in the first pipe section 21. This reduces pressure loss and thus reduces the decrease in flow velocity. Therefore, a flow velocity that can efficiently generate fine bubbles can be easily obtained.

[0051] Furthermore, when the flow rate in the first pipe section 21 decreases, as shown in Figure 2, the amount of liquid attempting to flow from the branch pipe section 29 into the widened section 252 decreases, and the water pressure in the widened section 252 decreases. As a result, the restoring force of the biasing section 332 causes the diaphragm 331, which had been deformed to one side in the axial direction, to return to its original shape, bringing the valve body 31 closer to the constricted pipe section 24. This reduces the gap d between the constricted pipe section 24 and the valve body 31. In other words, the flow path cross-sectional area in the constricted pipe section 24 decreases in proportion to the decrease in the flow rate in the first pipe section 21. This allows the fluid to swirl at high speed in a narrow space even when the flow rate decreases. Therefore, a swirling speed that can efficiently generate fine bubbles can be easily obtained.

[0052] As described above, according to the fine bubble generator 1 of this embodiment, the size of the flow path cross-sectional area of ​​the constricted pipe section 24 is changed according to the flow rate of the first pipe section 21. Therefore, even if the flow rate in the first pipe section 21 changes, fluctuations in the liquid pressure and flow velocity in the constricted pipe section 24 can be reduced, and thus the fine bubble generation efficiency can be stabilized by the fluctuation in flow rate.

[0053] Furthermore, as shown in Figures 2 and 4, the opening area of ​​the inlet P1 changes depending on the position of the valve body 31. When the flow rate of the first pipe section 21 is small, the overlap between the guide ring 43 and the inlet P1 increases, and the opening area of ​​the inlet P1 decreases (Figure 2). Conversely, when the flow rate of the first pipe section 21 is relatively large, the overlap between the guide ring 43 and the inlet P1 decreases due to the retraction of the valve body 31, and the opening area of ​​the inlet P1 increases (Figure 4). In this way, by changing the opening area of ​​the inlet P1 in correlation with the flow rate of the first pipe section 21, the flow velocity of the liquid flowing from the first pipe section 21 into the valve housing 25 can be adjusted to an appropriate size. Therefore, even when the flow rate of the first pipe section 21 fluctuates, the fine bubble generation efficiency can be stabilized.

[0054] <2. Second Embodiment> Next, a second embodiment will be described. In the following description, elements having the same function as those already described will be given the same reference numeral or a reference numeral with an additional alphabetic character, and detailed descriptions may be omitted.

[0055] Figure 5 is a cross-sectional view showing a fine bubble generator 1A according to the second embodiment. The fine bubble generator 1A differs from the fine bubble generator 1 mainly in that a flow path is formed in the valve housing 25a so that the liquid moves back and forth in the axial direction.

[0056] In detail, the variable mechanism 27a has a movable cylindrical portion 35. The movable cylindrical portion 35 is a cylindrical member that extends axially with axis A1 as its central axis. The inner circumferential surface of the movable cylindrical portion 35 is inclined radially inward with a constant inclination toward the other axial direction. A valve body 31 is arranged inside the movable cylindrical portion 35. The other axial end of the movable cylindrical portion 35 is fixed to the flange portion 41 of the guide portion 333. Therefore, the movable cylindrical portion 35 is movable axially together with the valve body 31.

[0057] The fine bubble generator 1A includes a fixed cylindrical section 51. The fixed cylindrical section 51 is located on the other axial side (downstream side) of the constricted pipe section 24. In this embodiment, the fixed cylindrical section 51 has a configuration integrated with the constricted pipe section 24. The fixed cylindrical section 51 is housed within the movable cylindrical section 35. The outer circumferential surface of the fixed cylindrical section 51 is inclined radially inward with a constant inclination toward the other axial direction. The fixed cylindrical section 51 is inserted radially inward into the movable cylindrical section 35. The outer circumferential surface of the fixed cylindrical section 51 and the inner circumferential surface of the movable cylindrical section 35 face each other with a gap between them.

[0058] The liquid flowing from the first pipe section 21 into the valve housing 25 first flows axially in one direction while swirling outside the movable cylindrical section 35, and then flows axially in the other direction while swirling in the gap between the movable cylindrical section 35 and the fixed cylindrical section 51. After that, the liquid flows axially in one direction while swirling inside the fixed cylindrical section 51 and passes through the gap between the constricted pipe section 24 and the valve body 31. In this way, with the fine bubble generator 1A, the flow path is formed so that the liquid reciprocates in the axial direction, making it possible to form a long swirling flow in a limited space.

[0059] Furthermore, in the case of the fine bubble generator 1A, when the flow rate of the first pipe section 21 is small, the force of the biasing section 332 causes the movable cylindrical section 35 to approach the fixed cylindrical section 51 together with the valve body 31, thereby reducing the cross-sectional area of ​​the flow path between the movable cylindrical section 35 and the fixed cylindrical section 51. This allows the fluid to swirl at high speed in a narrow space. A swirling speed that can efficiently generate fine bubbles can be easily obtained.

[0060] Furthermore, when the flow rate in the first pipe section 21 increases, the movable cylindrical section 35 moves axially to the other side together with the valve body 31, and the movable cylindrical section 35 moves away from the fixed cylindrical section 51. As a result, the cross-sectional area of ​​the flow path between the movable cylindrical section 35 and the fixed cylindrical section 51 increases. This reduces pressure loss even when the flow rate increases, thus mitigating the decrease in flow velocity (swirling speed). Therefore, a swirling speed that can efficiently generate fine bubbles can be easily obtained.

[0061] As described above, with the fine bubble generator 1A, the cross-sectional area of ​​the flow path between the movable cylindrical section 35 and the fixed cylindrical section 51 is changed in correlation with the flow rate of the first pipe section 21. Therefore, even when fluctuations occur in the liquid flow rate, the fine bubble generation efficiency can be further stabilized.

[0062] <3. Third Embodiment> Figure 6 is a cross-sectional view of the fine bubble generator 1B according to the third embodiment. The fine bubble generator 1B comprises, in order from the upstream side, a first pipe section 21, a constricted pipe section 24, a valve housing 25b, and a second pipe section 23. The first pipe section 21, the constricted pipe section 24, the valve housing 25b, and the second pipe section 23 are arranged coaxially with respect to axis A1. The head 310 of the valve body 31 located in the valve housing 25b is directed toward the constricted pipe section 24 on the other axial side. The head 310 is inserted into the portion of the constricted pipe section 24 where the inner diameter (inner width) increases toward one axial side.

[0063] The forward / backward drive unit 33b of this embodiment has a base portion 335 fixed inside the valve housing 25b. The base portion 335 is formed in a bottomed cylindrical shape that extends along the axis A1. A biasing portion 332b and a guide portion 333b are housed inside the base portion 335.

[0064] The biasing portion 332b has one axial end fixed to the base portion 335 and the other axial end fixed to the flange portion 41b of the guide portion 333b. The biasing portion 332b biases the flange portion 41b and the valve body 31 toward the constricted pipe portion 24. The guide ring 43b of the guide portion 333b slides axially against the inner circumferential surface of the base portion 335. This reduces vibration or lateral displacement of the valve body 31 during movement.

[0065] In the fine bubble generator 1B, when the flow rate of the first pipe section 21 increases, the water pressure of the liquid flowing into the valve housing 25 increases, pushing the head 310 of the valve body 31 axially to one side, causing the valve body 31 to move away from the constricted pipe section 24. This increases the gap between the valve body 31 and the constricted pipe section 24, and increases the opening cross-sectional area of ​​the constricted pipe section 24. As a result, even when the flow rate increases, pressure loss can be reduced, thus mitigating the decrease in flow velocity. Furthermore, when the flow rate of the first pipe section 21 decreases, the flange section 41b is pushed axially to the other side by the restoring force of the biasing section 332. This causes the valve body 31 to move closer to the constricted pipe section 24, reducing the opening cross-sectional area of ​​the constricted pipe section 24. Therefore, the decrease in flow velocity can be suppressed. Consequently, even when the flow rate of the first pipe section 21 fluctuates, the fine bubble generation efficiency can be stabilized.

[0066] <4. Fourth Embodiment> Figure 7A is a perspective view showing a fine bubble generator 1C according to the fourth embodiment. The fine bubble generator 1C has a first pipe section 21, a constricted pipe section 24c, and a second pipe section 23. The constricted pipe section 24c has a pair of cylindrical tanks 241. The cylindrical tanks 241 are cylindrical members extending along axis A2. Inside each cylindrical tank 241, a cylindrical body 243 is housed. Inside the cylindrical tank 241, a circular flow path is formed by the inner circumferential surface of the cylindrical tank 241 and the outer circumferential surface of the cylindrical body 243. The cylindrical body 243 is eccentrically positioned with respect to the cylindrical tank 241. Therefore, each cylindrical tank 241 has a constricted section in which the flow path cross-sectional area decreases towards the downstream. The top of each cylindrical tank 241 is closed by a lid (not shown).

[0067] Figure 7B is a schematic cross-sectional view of the fine bubble generator 1C at the position indicated by line BB in Figure 7A. The first pipe section 21 is connected to both inlets P3 provided in the pair of cylindrical tanks 241 at the center of the constricted pipe section 24c (between the pair of cylindrical tanks 241). As shown in Figure 7B, the liquid flowing from the first pipe section 21 into the constricted pipe section 24c is divided into each of the pair of cylindrical tanks 241 and enters each cylindrical tank 241. It then begins to swirl as it passes through the circular flow path within the cylindrical tanks 241.

[0068] Figure 7C is a schematic cross-sectional view of the fine bubble generator 1C at the CC line position shown in Figure 7A. The second pipe section 23 is flow-connected to the constricted pipe section 24c on the side opposite to the first pipe section 21. The second pipe section 23 is connected to the outlet P4 provided in the pair of cylindrical tanks 241 at the center of the constricted pipe section 24c. The second pipe section 23 is flow-connected to the constricted pipe section 24c at a position above the first pipe section 21. Fine bubbles are generated by swirling along the inner circumferential surface of the pair of cylindrical tanks 241 and passing through the constricted section where the flow path cross-sectional area is small. The liquid that has swirled in the pair of cylindrical tanks 241 merges in the center of the constricted pipe section 24c and is discharged from the second pipe section 23. At this merging point, the swirling flows in the pair of cylindrical tanks 241 collide, further refining the fine bubbles. As a result, the liquid containing the refined fine bubbles is discharged from the second pipe section 23. Furthermore, a liquid containing microbubbles may be supplied to the first pipe section 21. In this case, even finer ultrafine bubbles can be generated from the microbubbles.

[0069] Figure 7D is a schematic cross-sectional view of the fine bubble generator 1C at the position indicated by the DD line in Figure 7A. As shown in Figure 7D, a variable mechanism 27c is provided at the bottom of each cylindrical tank 241 in the constricted pipe section 24c. The variable mechanism 27c has a support plate 361 and a biasing part 363 (second biasing part) that supports the support plate 361. The support plate 361 has a shape corresponding to the inner shape of the cylindrical tank 241 and is supported so as to be movable up and down along axis A2 relative to the cylindrical tank 241. A cylindrical body 243 is fixed to the upper part of the support plate 361. The biasing part 363 is fixed to the bottom of the cylindrical tank 241 and biases the support plate 361 upward. The biasing part 363 is an elastic body such as a coil spring arranged to expand and contract vertically.

[0070] When the flow rate of the first pipe section 21 increases, the amount of liquid flowing into each cylindrical tank 241 increases, and the pressure of the liquid flowing inside each cylindrical tank 241 increases. As a result, the support plate 361 is pushed downward in proportion to the magnitude of the pressure. This increases the cross-sectional area of ​​the flow path in the cylindrical tank 241. Because the cross-sectional area of ​​the flow path increases, pressure loss can be reduced even when the flow rate increases, thus reducing the decrease in flow velocity. Therefore, even when the liquid flow rate increases, the fine bubble generation efficiency can be stabilized.

[0071] On the other hand, when the flow rate in the first pipe section 21 decreases, the pressure in each cylindrical tank 241 decreases. As a result, the support plate 361, which was pushed down, is pushed up by the force (restoring force) of the biasing section 363. This reduces the flow path cross-sectional area in the cylindrical tank 241, thereby mitigating the decrease in flow velocity within the cylindrical tank 241. Therefore, even if the liquid flow rate decreases, the fine bubble generation efficiency can be stabilized.

[0072] <5. Fifth Embodiment> Figure 8 is a schematic cross-sectional view showing a fine bubble generator 1D according to the fifth embodiment. In the fine bubble generator 1D, the first pipe section 21, the constricted pipe section 24, and the second pipe section 23 are arranged coaxially with respect to axis A1. The variable mechanism 27d of this embodiment has a variable pipe section 371 positioned in the middle of the constricted pipe section 24. The variable pipe section 371 forms a flow path together with the constricted pipe section 24. The variable pipe section 371 has a constricted tubular structure. In this embodiment, the variable pipe section 371 forms the narrowest part of the constricted pipe section 24. The variable pipe section 371 is made of an elastic material such as rubber and deforms in response to water pressure. That is, the flow path cross-sectional area of ​​the variable pipe section 371 changes in correlation with water pressure.

[0073] In the fine bubble generator 1D, when the flow rate of the first pipe section 21 increases, the variable pipe section 371 provided in the constricted pipe section 24 expands, increasing the flow path cross-sectional area of ​​the constricted pipe section 24. This reduces the increase in flow velocity and water pressure associated with the increase in flow rate. Conversely, when the flow rate of the first pipe section 21 decreases, the variable pipe section 371 contracts, reducing the flow path cross-sectional area of ​​the constricted pipe section 24. This reduces the decrease in flow velocity and water pressure associated with the decrease in flow rate. Therefore, even when the liquid flow rate fluctuates, the fine bubble generation efficiency can be stabilized.

[0074] <6. Sixth Embodiment> Figure 9 is a schematic cross-sectional view showing a fine bubble generator 1E according to the sixth embodiment. In the fine bubble generator 1E, similar to the fine bubble generator 1D, the first pipe section 21, the constricted pipe section 24, and the second pipe section 23 are arranged coaxially around axis A1. The variable mechanism 27e of this embodiment includes a variable pipe section 373, a pair of pressers 374, a water pressure sensor 375, and a control unit 376.

[0075] The variable pipe section 373 is positioned in the middle of the constricted pipe section 24 and together with the constricted pipe section 24 forms a flow path. A pair of pressers 374 are positioned to sandwich the variable pipe section 373 from both sides. The pressers 374 are composed of mechanisms such as a cylinder that generates linear motion using compressed air or hydraulic pressure, or a ball screw that converts the rotational motion of a motor into linear motion.

[0076] The water pressure sensor 375 measures the water pressure in the first pipe section 21. The water pressure sensor 375 converts the detected pressure into an electrical signal and outputs it to the control unit 376. The control unit 376 controls the press 374 according to the pressure measured by the water pressure sensor 375. The control unit 376 is composed of a computer equipped with a processor such as a CPU and memory such as RAM. However, the control unit 376 may also be composed of electrical circuits such as a programmable logic controller (PLC), relay circuit, or PID controller.

[0077] The control unit 376 maximizes the pressing force of the presser 374 when the water pressure measured by the water pressure sensor 375 is zero. The control unit 376 also controls the pressing force of the presser 374 to decrease as the water pressure increases. Through this control, the fine bubble generator 1E, like the fine bubble generator 1D, changes the flow path cross-sectional area of ​​the narrowed pipe section 24 in correlation with the flow rate of the first pipe section 21. Therefore, even when the flow rate fluctuates, the fine bubble generation efficiency can be stabilized.

[0078] <7. Seventh Embodiment> Figure 10 is a schematic cross-sectional view showing a fine bubble generator 1F according to the seventh embodiment. In the fine bubble generator 1F, the constricted pipe section 24f and the second pipe section 23 are arranged coaxially with respect to the axis A1. The variable mechanism 27f of the fine bubble generator 1F is composed of a valve body 38 provided inside the constricted pipe section 24. The valve body 38 is positioned on axis A1. The valve body 38 is composed of a pair of leaf sections 381. The leaf sections 381 are composed of thin, crescent-shaped membranes. Each leaf section 381 is inclined radially inward toward the downstream. That is, the valve body 38 is formed such that its inner width decreases toward one side in the axial direction. Therefore, the valve body 38 constitutes a constricted section in the constricted pipe section 24f where the flow path cross-sectional area decreases toward the downstream.

[0079] The fine bubble generator 1F is equipped with a rod member 53. The rod member 53 is formed in a cylindrical shape, extending along the axis A1 with the axis A1 as its center. The tip of the rod member 53 is located between a pair of leaf portions 381 of the valve body 38. As a result, the flow path cross-sectional area of ​​the constricted pipe portion 24f is further narrowed by the rod member 53.

[0080] A spiral groove 531 is provided at the downstream end of the rod member 53. As the liquid flows from the first pipe section 21 into the narrowed pipe section 24f, it is concentrated in the groove 531 of the rod member 53 as it moves towards the tip of the valve body 38. As a result, the liquid passes through the valve body 38 while swirling along the groove 531. This allows for the efficient generation of fine bubbles.

[0081] The valve body 38 changes the flow path cross-sectional area according to the flow rate of the first pipe section 21. Specifically, when the flow rate of the first pipe section 21 increases, the flow rate inside the valve body 38 increases, and the water pressure on the valve body 38 rises. As a result, the pair of leaf sections 381 move outward (away from each other) due to the water pressure. Also, the pair of leaf sections 381 move away from the rod member 53. This increases the flow path cross-sectional area of ​​the constricted pipe section 24f.

[0082] Furthermore, when the flow rate in the first pipe section 21 decreases, the water pressure on the valve body 38 decreases, causing the pair of leaf sections 381 to move inward. Also, the gap between the pair of leaf sections 381 and the rod member 53 becomes smaller. As a result, the cross-sectional area of ​​the flow path in the constricted pipe section 24f decreases.

[0083] As described above, with the fine bubble generator 1F, similar to the fine bubble generator 1, the flow path cross-sectional area of ​​the narrowed pipe section 24f can be changed in correlation with the flow rate of the first pipe section 21. Therefore, even when the liquid flow rate fluctuates, the fine bubble generation efficiency can be stabilized.

[0084] <8. Eighth Embodiment> Figure 11 is a schematic cross-sectional view showing the fine bubble generator 1G according to the eighth embodiment. The fine bubble generator 1G differs from the fine bubble generator 1F shown in Figure 10 in that it is equipped with a variable mechanism 27g.

[0085] The variable mechanism 27g has a valve body 39. The valve body 39 is located within the constricted pipe section 24f and moves along the inner circumferential surface of the constricted pipe section 24f. The valve body 39 has a cylindrical shape that extends axially with axis A1 as its center. The outer diameter of the valve body 39 is constant in the axial direction. The inner diameter of the valve body 39 gradually decreases toward one side in the axial direction. Therefore, the valve body 39 constitutes a constricted section in the constricted pipe section 24f where the flow path cross-sectional area decreases toward the downstream direction.

[0086] Furthermore, the rod member 53 is positioned at the center of the valve body 39. The tip of the rod member 53 (the portion where the groove 531 is formed) is located inside the valve body 39. As a result, the flow path cross-sectional area of ​​the constricted pipe section 24f is further narrowed by the rod member 53.

[0087] One axial side of the valve body 39 is connected to the constricted pipe section 24f via a biasing part 391. The biasing part 391 is a member that biases the valve body 39 in the other axial direction (downstream). The biasing part 391 is fixed to the constricted pipe section 24f at a position axially to one side of the valve body 39. The biasing part 391 is an elastic body, such as a coil spring.

[0088] The valve body 39 changes its flow path cross-sectional area according to the flow rate of the first pipe section 21. For example, when the flow rate of the first pipe section 21 increases, the flow rate inside the valve body 39 increases, and the water pressure acting on the valve body 39 also increases. As a result, the valve body 39 moves axially in one direction (downstream) against the force acting on it from the biasing part 391. This increases the gap between the inner circumferential surface of the valve body 39 and the tip of the rod member 53. Therefore, as the flow rate of the first pipe section 21 increases, the flow path cross-sectional area of ​​the constricted pipe section 24f increases.

[0089] Furthermore, when the flow rate in the first pipe section 21 decreases, the water pressure on the valve body 39 decreases, causing the valve body 39 to move axially to the other side (upstream) by the force of the biasing part 391. As a result, the gap between the inner surface of the valve body 39 and the tip of the rod member 53 becomes smaller. Therefore, the flow path cross-sectional area of ​​the constricted pipe section 24f decreases in accordance with the decrease in the flow rate in the first pipe section 21.

[0090] With the fine bubble generator 1G, similar to the fine bubble generator 1, the flow path cross-sectional area of ​​the narrowed pipe section 24f can be changed in correlation with the flow rate of the first pipe section 21. Therefore, even when the liquid flow rate fluctuates, the fine bubble generation efficiency can be stabilized.

[0091] Although this invention has been described in detail, the above description is illustrative in all respects, and the invention is not limited thereto. It is understood that countless variations not illustrated can be conceived without falling outside the scope of this invention. The components described in each of the above embodiments and variations can be combined or omitted as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0092] 1,1A-1G: Fine bubble generator 10: Supply section 21: First Section 23: Second Section 24,24c,24f: Constricted tube part 25, 25a, 25b: Valve housing 27, 27a, 27c-27g: Variable mechanism 29: Branch pipe section 31: Valve body 33,33b: Reverse drive unit 38,39: Valve body 43,43b: Guide ring 100: Cleaning equipment (substrate processing equipment) 241: Cylindrical tank 243: Cylinder 311: Shaft 331: Diaphragm 332: Encouraging part 332b: Biasing part 333: Guide Section 334: Bearing part 361: Support plate 363: Biasing part (second biasing part) A1: Axis P1:Inlet

Claims

1. It is a fine bubble generator, The first pipe section and, A second pipe section located downstream of the first pipe section, A constricted pipe section located between the first pipe section and the second pipe section, having a portion where the cross-sectional area of ​​the flow path decreases towards the downstream direction, A variable mechanism that changes the flow path cross-sectional area in the constricted pipe section according to the flow rate of the first pipe section, A fine bubble generator equipped with the following features.

2. A fine bubble generator according to claim 1, The present invention further comprises a valve housing located between the first pipe section and the second pipe section, to which the first pipe section is connected, The aforementioned variable mechanism is A movable valve body is positioned inside the valve housing, A reciprocating drive unit moves the valve body forward and backward relative to the constricted pipe section according to the flow rate of the first pipe section, A fine bubble generator equipped with the following features.

3. A fine bubble generator according to claim 2, The aforementioned reciprocating drive unit is housed within the valve housing. The aforementioned reciprocating drive unit is A diaphragm connected to the valve body, which deforms to move the valve body according to the flow rate of the first pipe section, A biasing unit that biases the valve body connected to the diaphragm toward the constricted pipe section, A fine bubble generator.

4. A fine bubble generator according to claim 3, A branch pipe section that branches off midway through the first pipe section and is connected to the valve housing, Furthermore, A fine bubble generator wherein the branch pipe section is connected to the valve housing closer to the diaphragm than the first pipe section.

5. A fine bubble generator according to claim 2, The aforementioned reciprocating drive unit further includes a guide unit that guides the movement of the valve body, wherein the fine bubble generator is provided.

6. A fine bubble generator according to claim 3, The valve body has a shaft portion connected to the diaphragm, The fine bubble generator further comprises a bearing portion that supports the shaft portion so as to be movable relative to the constricted pipe portion.

7. A fine bubble generator according to claim 2, The valve housing has an inlet located at a position offset radially from the central axis, The first pipe section is a fine bubble generator connected to the inlet.

8. A fine bubble generator according to claim 2, The valve body is inserted into the portion of the narrowed pipe where the flow path cross-sectional area increases towards the downstream side. The aforementioned reciprocating drive unit is a fine bubble generator located downstream of the constricted pipe section.

9. A fine bubble generator according to claim 1 or claim 2, The aforementioned constricted pipe section has a cylindrical tank and a cylindrical body disposed within the cylindrical tank. The aforementioned variable mechanism is The cylindrical body is attached to the upper surface, and a support plate is provided that is movable up and down inside the cylindrical tank, A second biasing unit that biases the support plate upward, A fine bubble generator.

10. A processing liquid supply device, A fine bubble generator according to claim 1 or claim 2, A supply unit that supplies a processing liquid containing fine bubbles generated by the fine bubble generator to the object to be processed, A processing liquid supply device equipped with the following features.

11. A substrate processing apparatus, Support part that supports the circuit board, A fine bubble generator according to claim 1 or claim 2, A supply unit that supplies a processing liquid containing fine bubbles generated by the fine bubble generator to the substrate supported by the support unit, A substrate processing apparatus comprising:

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