Microbubble generating nozzle

Abstract

To provide a technology to reduce cavitation sound.SOLUTION: A fine bubble generation nozzle includes a nozzle unit and an insulation body. The nozzle unit includes an inflow port into which gas-dissolved pressurized water in which a gas is dissolved in water flows, a decompression part for decompressing a pressure of the gas-dissolved pressurized water flowing from the inflow port, a first collision chamber provided on a downstream side of the decompression part having a first collision wall for changing a direction of a flow channel of the gas-dissolved pressurized water when the gas-dissolved pressurized water flowing from the decompression part collides with the first collision wall, a second collision chamber provided on a downstream side of the first collision chamber having a second collision wall for changing the direction of the flow channel of the gas-dissolved pressurized water when the gas-dissolved pressurized water passing through the first collision chamber collides with the second collision wall, and an outflow port from which the gas-dissolved pressurized water passing through the second collision chamber flows out. The insulation body is disposed at a position facing the outflow port at an outside the nozzle unit.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The technology disclosed in this specification relates to a microbubble generation nozzle.

Background Art

[0002] Patent Document 1 discloses a microbubble generation nozzle including a nozzle unit. The nozzle unit includes an inlet through which gas-dissolved pressurized water in which gas is dissolved in water flows in, a decompression unit that decompresses the pressure of the gas-dissolved pressurized water flowing in from the inlet, a first collision chamber provided on the downstream side of the decompression unit and having a first collision wall that changes the direction of the flow path of the gas-dissolved pressurized water by the gas-dissolved pressurized water flowing in from the decompression unit colliding therewith, a second collision chamber provided on the downstream side of the first collision chamber and having a second collision wall that changes the direction of the flow path of the gas-dissolved pressurized water by the gas-dissolved pressurized water passing through the first collision chamber colliding therewith, and an outlet through which the gas-dissolved pressurized water passing through the second collision chamber flows out.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the microbubble generating nozzle of Patent Document 1, the gas-dissolved pressurized water is reduced to a pressure lower than atmospheric pressure by passing through a depressurization section. During the process of reducing the pressure of the gas-dissolved pressurized water, the gas dissolved in the water precipitates, and bubbles are generated in the gas-dissolved pressurized water. Then, as the gas-dissolved pressurized water passes through the first and second impaction chambers, the pressure in the gas-dissolved pressurized water is gradually increased. As the pressure of the gas-dissolved pressurized water increases, some of the bubbles in the gas-dissolved pressurized water split and become microbubbles. Then, when the gas-dissolved pressurized water flows out from the outlet, the pressure of the gas-dissolved pressurized water is increased to atmospheric pressure, and some of the bubbles remaining in the gas-dissolved pressurized water split and become microbubbles. In the nozzle unit of the above microbubble generating nozzle, there may be localized areas of high negative pressure in the flow path downstream of the depressurization section. When there are localized areas of high negative pressure, bubbles generated during the process of reducing the pressure of the gas-dissolved pressurized water may burst. The bursting of air bubbles generates cavitation noise.

[0005] This specification provides a technology that can reduce cavitation noise. [Means for solving the problem]

[0006] In a first aspect of this technology, the microbubble generating nozzle comprises a nozzle unit and a shielding body, the nozzle unit comprising: an inlet into which pressurized water containing dissolved gas flows in; a pressure reducing section for reducing the pressure of the pressurized water containing dissolved gas flowing in from the inlet; a first impact chamber provided downstream of the pressure reducing section and having a first impact wall that changes the direction of the flow path of the pressurized water containing dissolved gas by impacting the pressurized water containing dissolved gas flowing in from the pressure reducing section; a second impact chamber provided downstream of the first impact chamber and having a second impact wall that changes the direction of the flow path of the pressurized water containing dissolved gas by impacting the pressurized water containing dissolved gas that has passed through the first impact chamber; and an outlet through which the pressurized water containing dissolved gas that has passed through the second impact chamber flows out, the shielding body being positioned on the outside of the nozzle unit opposite the outlet.

[0007] In the above configuration, the pressurized water containing dissolved gas flowing out of the nozzle unit's outlet collides with the shielding. Because the pressurized water containing dissolved gas collides with the shielding, the overall pressure loss of the microbubble generation nozzle increases. In this case, the pressure inside the nozzle unit can be increased compared to a configuration in which the pressurized water containing dissolved gas flowing out of the nozzle unit's outlet does not collide with the shielding. Therefore, the negative pressure in areas with locally high negative pressure inside the nozzle unit can be reduced. This suppresses the bursting of bubbles inside the nozzle unit. Consequently, cavitation noise can be reduced. Note that a large negative pressure means a large pressure difference with atmospheric pressure, and a small negative pressure means a small pressure difference with atmospheric pressure.

[0008] In the second embodiment, in the first embodiment, when the microbubble generating nozzle is viewed from the shielding side in a first direction along the flow path axis of the flow path connecting the second collision wall and the outlet, the shielding body may completely cover the outlet.

[0009] With the above configuration, a large portion of the pressurized water containing dissolved gas flowing out of the outlet can be made to collide with the shielding. In this case, the overall pressure loss of the microbubble generation nozzle becomes greater, and the pressure inside the nozzle unit can be increased. Therefore, the negative pressure in areas with high localized negative pressure within the nozzle unit can be reduced. Consequently, the bursting of bubbles inside the nozzle unit can be further suppressed, and cavitation noise can be further reduced.

[0010] In a third embodiment, in the first or second embodiment, the first impact wall is provided on the first side of the pressure reduction section in a second direction along the central axis of the nozzle unit, the second impact wall is provided on the second side opposite to the first side of the first impact wall, the outlet is provided between the first impact wall and the second impact wall, and the shielding body may be provided between the first impact wall and the outlet.

[0011] When the distance between the outlet and the shield is large, even if the pressurized water containing dissolved gas flowing out of the nozzle unit's outlet collides with the shield, the overall pressure loss of the microbubble generation nozzle does not increase significantly. With the above configuration, the distance between the outlet and the shield can be shortened, the overall pressure loss of the microbubble generation nozzle can be reliably increased, and the pressure inside the nozzle unit can be reliably increased. In other words, the negative pressure in areas with locally large negative pressure within the nozzle unit can be reliably reduced. Therefore, cavitation noise can be reliably reduced.

[0012] In the fourth embodiment, in any one of the first to third embodiments described above, the shielding body may be made of an elastic material.

[0013] With the above configuration, even if bubbles burst within the nozzle unit, the impact caused by the bursting bubbles is absorbed by the shielding material. Therefore, cavitation noise can be further reduced.

[0014] In the fifth embodiment, in any one of the first to fourth embodiments, the nozzle unit may include a mounting portion for attaching the shielding body. When the shielding body is attached to the mounting portion, a gap may be provided between the mounting portion and the shielding body.

[0015] According to the above configuration, when the shielding body is attached to the mounting part, the shielding body can move relative to the mounting part by the amount of the gap between the mounting part and the shielding body. As the shielding body moves relative to the mounting part, the shock caused by the bursting of bubbles is absorbed. Therefore, compared to a configuration in which there is no gap between the mounting part and the shielding body, the shielding body can absorb the shock caused by the bursting of bubbles more effectively. Consequently, cavitation noise can be reduced more effectively.

[0016] In the sixth embodiment, in any one of the first to fifth embodiments, the first impact wall is located on the first side of the depressurization section in a second direction along the central axis of the nozzle unit, the outlet is located between the first impact wall and the second impact wall, and the second impact wall may be located on the second side opposite to the first side of the first impact wall. The nozzle unit may further include a peripheral wall portion extending from the outer peripheral end of the first impact wall to the second side in the second direction, defining a flow path between the first impact chamber and the second impact chamber. The mounting portion protrudes outward from the peripheral wall portion, and when the shielding body is attached to the mounting portion, the first side end of the shielding body may be located on the second side of the first impact wall.

[0017] With the above configuration, the length of the microbubble generating nozzle in the front-rear direction can be shortened compared to a configuration in which the first side end of the shielding body is located on the first side of the first collision wall. [Brief explanation of the drawing]

[0018] [Figure 1] This is a perspective view of the microbubble generating nozzle 10 according to the first embodiment, viewed from the front left and above. [Figure 2] This is a perspective view of the microbubble generating nozzle 10 according to the first embodiment, viewed from the rear left and above. [Figure 3] This is a perspective view of the nozzle body 20 according to the first embodiment, viewed from the front left and above. [Figure 4] This is a cross-sectional view of the microbubble generating nozzle 10 according to the first embodiment, viewed from above. [Figure 5] This is a perspective view of the holder portion 22 according to the first embodiment, viewed from the rear left and above. [Figure 6] This is a cross-sectional view of the microbubble generating nozzle 10 according to the first embodiment, viewed from the left. [Figure 7] This is a perspective view of the shielding body 14 according to the first embodiment, viewed from the rear left and above. [Figure 8] This is a front view of the microbubble generating nozzle 10 according to the first embodiment. [Figure 9] It is a perspective view of the fine bubble generation nozzle 210 according to the second embodiment, seen from the front upper left. [Figure 10] It is a cross-sectional view of the fine bubble generation nozzle 210 according to the second embodiment, seen from above. [Figure 11] It is a cross-sectional view of the fine bubble generation nozzle 210 according to the second embodiment, seen from the left. [Figure 12] It is a front view of the fine bubble generation nozzle 210 according to the second embodiment.

Mode for Carrying Out the Invention

[0019] (Configuration of the fine bubble generation nozzle 10) As shown in FIG. 1, the fine bubble generation nozzle 10 includes a nozzle unit 12 and a shielding body 14. The fine bubble generation nozzle 10 is a nozzle for generating fine bubbles in a bathtub (not shown) or the like. Hereinafter, the direction parallel to the central axis C1 of the fine bubble generation nozzle 10 is referred to as the front-rear direction, the direction in which the connecting portion 44 of the nozzle unit 12 described later is provided with respect to the central axis C1 is referred to as the left-right direction, and the direction orthogonal to the front-rear direction and the left-right direction is referred to as the up-down direction.

[0020] (Configuration of the nozzle unit 12) As shown in Figure 2, the nozzle unit 12 comprises a nozzle body 20 and a holder portion 22. The nozzle body 20 and the holder portion 22 are made of resin. The nozzle body 20 is attached to the holder portion 22. The nozzle body 20 comprises two pressure reducing sections 30, a first body-side cylindrical portion 32, a body-side disc portion 34, and a second body-side cylindrical portion 36 (see Figure 3). The two pressure reducing sections 30 are arranged side by side in the left-right direction. As shown in Figure 4, the pressure reducing section 30 comprises an inlet 30a, a diameter-reducing channel 30b, a diameter-expanding channel 30c connected to the rear end of the diameter-reducing channel 30b, and an outlet 30d. A water supply pipe (not shown) for supplying pressurized water containing dissolved air to the microbubble generating nozzle 10 is connected to the inlet 30a. The diameter of the diameter-reducing channel 30b decreases in stages from rear to front. The diameter of the expanded flow channel 30c gradually increases as it moves from the rear to the front. In this embodiment, the diameter of the expanded flow channel 30c is set such that the pressure of the air-dissolved pressurized water after passing through the expanded flow channel 30c is lower than atmospheric pressure. The central axis C2 of the depressurization section 30 is parallel to the central axis C1. The main body side disc portion 34 is provided between the first main body side cylindrical portion 32 and the second main body side cylindrical portion 36. The outer diameter of the main body side disc portion 34 is larger than the outer diameter of the first main body side cylindrical portion 32 and the outer diameter of the second main body side cylindrical portion 36. As shown in Figure 2, two protrusions 34a are connected to the main body side disc portion 34, projecting outward from the outer circumferential surface of the main body side disc portion 34. The two protrusions 34a are connected to the upper and lower parts of the main body side disc portion 34. As shown in Figure 4, the outer diameter of the second main body side cylindrical portion 36 is smaller than that of the first main body side cylindrical portion 32.

[0021] As shown in Figure 1, the holder portion 22 comprises a first holder-side cylindrical portion 40, a second holder-side cylindrical portion 42 (see Figure 4), two connecting portions 44, a mounting portion 46 (see Figure 4), and a holder-side disc portion 48.

[0022] The two connecting parts 44 protrude outward from the left and right ends of the first holder-side cylindrical part 40. The connecting parts 44 are provided with screw holes B. The screw holes B of the connecting parts 44 are for attaching the holder part 22 to a bathtub connector (not shown). The bathtub connector is a device for attaching the microbubble generating nozzle 10 to the bathtub.

[0023] As shown in Figure 2, two notches 50 are provided at the rear of the first holder-side cylindrical portion 40. The two notches 50 are located at the upper and lower parts of the first holder-side cylindrical portion 40. The notches 50 have a shape that corresponds to the protruding portion 34a of the nozzle body 20.

[0024] As shown in Figure 5, the rear end of the second holder-side cylindrical portion 42 is connected to the first holder-side cylindrical portion 40 via four connecting portions 52. The outer diameter of the second holder-side cylindrical portion 42 is smaller than the inner diameter of the first holder-side cylindrical portion 40. The first holder-side cylindrical portion 40, the second holder-side cylindrical portion 42, and the four connecting portions 52 form four outlets 54. As shown in Figure 4, the inner diameter of the second holder-side cylindrical portion 42 is larger than the outer diameter of the second body-side cylindrical portion 36 of the nozzle body 20. That is, a gap is provided between the second holder-side cylindrical portion 42 and the second body-side cylindrical portion 36. The holder-side disc portion 48 is connected to the front end of the second holder-side cylindrical portion 42. The outer diameter of the holder-side disc portion 48 is the same as the outer diameter of the second holder-side cylindrical portion 42. Specifically, the second holder-side cylindrical portion 42 extends rearward from the outer peripheral end of the holder-side disc portion 48. A projection 49 that protrudes rearward is provided in the central part of the holder-side disc portion 48. The projection end (rear end) of the projection 49 is located between the nozzle 30d of the decompression section 30 and the front end 36a of the second main body-side cylindrical portion 36.

[0025] When the nozzle body 20 is attached to the holder portion 22, a first impact chamber 60, a first water channel 62, a second impact chamber 64, and a second water channel 66 (see Figure 6) are formed within the holder portion 22. The first impact chamber 60 is the region between the rear surface 48a of the holder-side disc portion 48 and the front end 36a of the second body-side cylindrical portion 36. The first impact chamber 60 is defined by the second holder-side cylindrical portion 42, the holder-side disc portion 48, and the protruding portion 49.

[0026] The first channel 62 is a channel connecting the first impact chamber 60 and the second impact chamber 64. The first channel 62 is defined by the second main body side cylindrical portion 36 and the second holder side cylindrical portion 42.

[0027] The second impact chamber 64 is the region between the rear end 42a of the second holder-side cylindrical portion 42 and the front surface 34b of the main body-side disc portion 34. The second impact chamber 64 is defined by the first holder-side cylindrical portion 40, the main body-side disc portion 34, and the second main body-side cylindrical portion 36. In this embodiment, the volume of the second impact chamber 64 is larger than the volume of the first impact chamber 60.

[0028] As shown in Figure 6, the second channel 66 is a channel connecting the second impact chamber 64 and the outlet 54. The second channel 66 is defined by the gap between the first holder-side cylindrical portion 40 and the second holder-side cylindrical portion 42.

[0029] The mounting portion 46 protrudes outward from the outer surface of the second holder side cylindrical portion 42. The mounting portion 46 is provided between the first collision chamber 60 and the second collision chamber 64 in the front-rear direction.

[0030] (Configuration of shielding body 14) The shielding body 14 in Figure 7 is made of an elastic material such as rubber. The shielding body 14 comprises a first shielding body side cylindrical portion 70, a second shielding body side cylindrical portion 72, and a third shielding body side cylindrical portion 74. As shown in Figure 6, the inner diameter of the first shielding body side cylindrical portion 70 is slightly larger than the outer diameter of the mounting portion 46. The second shielding body side cylindrical portion 72 extends forward from the front end of the first shielding body side cylindrical portion 70. When the shielding body 14 is attached to the mounting portion 46, the front end 72a of the second shielding body side cylindrical portion 72 is located slightly behind the front surface 48b of the holder side disc portion 48. The inner diameter of the second shielding body side cylindrical portion 72 is smaller than the inner diameter of the first shielding body side cylindrical portion 70 and slightly larger than the outer diameter of the second holder side cylindrical portion 42. The third shield side cylindrical portion 74 extends rearward from the rear end of the first shield side cylindrical portion 70. The rear end 74a of the third shield side cylindrical portion 74 is positioned between the first impact chamber 60 and the outlet 54. The distance L1 between the rear end 74a of the third shield side cylindrical portion 74 and the outlet 54 is 1 mm. The distance L1 is preferably in the range of 0.5 mm to 2 mm. The inner diameter of the third shield side cylindrical portion 74 is smaller than the inner diameter of the first shield side cylindrical portion 70, slightly larger than the outer diameter of the second holder side cylindrical portion 42, and slightly larger than the inner diameter of the second shield side cylindrical portion 72. The inner circumferential surface of the first shield side cylindrical portion 70, the rear surface of the second shield side cylindrical portion 72, and the front surface of the third shield side cylindrical portion 74 define a recess 76 that is radially recessed outward. The width of the recess 76 in the front-rear direction is the same as the width of the mounting portion 46 in the front-rear direction. When the shielding body 14 is attached to the mounting portion 46 of the nozzle unit 12, the shielding body 14 abuts against the mounting portion 46 of the nozzle unit 12 in the front-rear direction, and gaps are provided between the shielding body 14 and the mounting portion 46, and between the shielding body 14 and the second holder side cylindrical portion 42 in the radial direction. Also, as shown in Figure 8, when the microbubble generating nozzle 10 is viewed from the front, the four outlets 54 (see Figure 5) are completely covered by the shielding body 14.

[0031] Next, with reference to Figure 6, the microbubbles generated by the microbubble generating nozzle 10 will be explained. In Figure 6, the solid arrows indicate the water flow path.

[0032] First, the air-dissolved pressurized water flows into the microbubble generation nozzle 10 through the inlet 30a of the depressurization section 30. At this point, the pressure of the air-dissolved pressurized water is greater than atmospheric pressure. As the air-dissolved pressurized water passes through the narrowed-diameter channel 30b of the depressurization section 30, the flow velocity of the air-dissolved pressurized water increases, and as a result, the pressure of the air-dissolved pressurized water is reduced to a pressure lower than atmospheric pressure. At this point, bubbles are generated in the air-dissolved pressurized water. Then, as the air-dissolved pressurized water that has passed through the narrowed-diameter channel 30b of the depressurization section 30 flows through the widened-diameter channel 30c, the flow velocity of the air-dissolved pressurized water decreases. As a result of the decrease in flow velocity, the pressure of the air-dissolved pressurized water increases. As the pressure of the air-dissolved pressurized water increases, the bubbles in the air-dissolved pressurized water contract. As a result, some of the bubbles contained in the air-dissolved pressurized water split and become microbubbles.

[0033] Next, the air-dissolved pressurized water is ejected into the first impact chamber 60 of the holder section 22 through the nozzle 30d of the depressurization section 30. As the air-dissolved pressurized water is ejected into the first impact chamber 60, its flow velocity slows down. This further increases the pressure of the air-dissolved pressurized water, causing some of the bubbles in the air-dissolved pressurized water to further split into fine bubbles. Next, the air-dissolved pressurized water that collides with the holder-side disc section 48 flows into the second impact chamber 64 through the first waterway 62. As described above, the volume of the second impact chamber 64 is larger than the volume of the first impact chamber 60. Therefore, the flow velocity of the air-dissolved pressurized water that flows into the second impact chamber 64 slows down even further. This further increases the pressure of the air-dissolved pressurized water, causing some of the bubbles in the air-dissolved pressurized water to further split into fine bubbles.

[0034] Next, the air-dissolved pressurized water that collides with the disc portion 34 on the main body side passes through the second water channel 66 and the outlet 54 of the holder portion 22, and flows out from the outlet 54 of the nozzle unit 12. The air-dissolved pressurized water that flows out from the outlet 54 collides with the third shield side cylindrical portion 74 of the shielding body 14. In addition, some of the air-dissolved pressurized water collides with the first shield side cylindrical portion 70 of the shielding body 14. After that, the air-dissolved pressurized water flows out to an outlet such as a bathtub. The pressure of the air-dissolved pressurized water is increased to atmospheric pressure at the outlet. As a result, the bubbles remaining in the air-dissolved pressurized water that has passed through the second impact chamber 64 contract, and some of the bubbles further split into fine bubbles. The air-dissolved pressurized water that flows out to the outlet also contains the fine bubbles generated in the first impact chamber 60 and the second impact chamber 64. As a result, a large number of fine bubbles are generated at the outlet.

[0035] As described above, as shown in Figure 1, the microbubble generating nozzle 10 comprises a nozzle unit 12 and a shielding body 14. The nozzle unit 12 comprises an inlet 30a into which air-dissolved pressurized water, in which air (an example of "gas") is dissolved in water, flows in; a pressure reducing section 30 that reduces the pressure of the air-dissolved pressurized water flowing in from the inlet 30a; a first impact chamber 60 provided downstream of the pressure reducing section 30 and having a holder-side disc portion 48 (an example of a "first impact wall") that changes the direction of the flow path of the air-dissolved pressurized water flowing in from the pressure reducing section 30 by impacting it; a second impact chamber 64 provided downstream of the first impact chamber 60 and having a body-side disc portion 34 (an example of a "second impact wall") that changes the direction of the flow path of the air-dissolved pressurized water flowing in from the first impact chamber 60 by impacting it; and an outlet 54 through which the water that has passed through the second impact chamber 64 flows out. As shown in Figure 6, the shielding body 14 is positioned outside the nozzle unit 12, facing the outlet 54. With this configuration, the pressurized water with dissolved air flowing out from the outlet 54 of the nozzle unit 12 collides with the shielding body 14. Because the pressurized water with dissolved air collides with the shielding body 14, the overall pressure loss of the microbubble generating nozzle 10 increases. In this case, the pressure inside the nozzle unit 12 can be increased compared to a configuration in which the pressurized water with dissolved air flowing out from the outlet 54 of the nozzle unit 12 does not collide with the shielding body 14. Therefore, the negative pressure in areas with locally large negative pressure inside the nozzle unit 12 can be reduced. This makes it possible to suppress bubbles bursting inside the nozzle unit 12. Consequently, cavitation noise can be reduced.

[0036] Furthermore, as shown in Figure 8, in the front-to-back direction along the flow path axis of the channel connecting the main body disc portion 34 and the outlet 54 (an example of the "first direction"), when the microbubble generating nozzle 10 is viewed from the shielding body 14 side, the shielding body 14 completely covers the outlet 54. With the above configuration, much of the pressurized water with dissolved air flowing out from the outlet 54 collides with the shielding body 14. In this case, the overall pressure loss of the microbubble generating nozzle 10 becomes larger, and the pressure inside the nozzle unit 12 can be increased. As a result, the negative pressure in areas with large localized negative pressure inside the nozzle unit 12 can be reduced. Consequently, the bursting of bubbles inside the nozzle unit 12 can be further suppressed, and cavitation noise can be further reduced.

[0037] Furthermore, as shown in Figure 6, in the front-rear direction along the central axis C1 of the nozzle unit 12 (an example of the "second direction"), the holder-side disc portion 48 is located in front of the depressurization portion 30 (an example of the "first side"), the main body-side disc portion 34 is located behind the holder-side disc portion 48 (an example of the "second side"), the outlet 54 is located between the first impact chamber 60 and the second impact chamber 64, and the shielding body 14 is located between the first impact chamber 60 and the outlet 54. If the distance between the outlet 54 and the shielding body 14 is large, even if the pressurized water with dissolved air flowing out of the outlet 54 of the nozzle unit 12 collides with the shielding body 14, the overall pressure loss of the microbubble generating nozzle 10 will not increase. With the above configuration, the distance between the outlet 54 and the shielding body 14 can be shortened, the overall pressure loss of the microbubble generating nozzle 10 can be reliably increased, and the pressure inside the nozzle unit 12 can be reliably increased. In other words, the negative pressure in areas with locally high negative pressure within the nozzle unit 12 can be reliably reduced. Therefore, cavitation noise can be reliably reduced.

[0038] Furthermore, the shielding body 14 is made of an elastic material. With the above configuration, even if bubbles burst inside the nozzle unit 12, the impact caused by the bursting bubbles is absorbed by the shielding body 14. Therefore, cavitation noise can be further reduced.

[0039] Furthermore, as shown in Figure 4, the nozzle unit 12 includes a mounting portion 46 for attaching the shielding body 14. When the shielding body 14 is attached to the mounting portion 46, a gap is provided between the mounting portion 46 and the shielding body 14. With the above configuration, when the shielding body 14 is attached to the mounting portion 46, the shielding body 14 can move relative to the mounting portion 46 by the amount of the gap between the mounting portion 46 and the shielding body 14. In other words, the shielding body 14 can vibrate. By vibrating the shielding body 14, the shock caused by the bursting of bubbles is absorbed. Therefore, compared to a configuration in which there is no gap between the mounting portion 46 and the shielding body 14, the shielding body 14 can absorb the shock caused by the bursting of bubbles more effectively. Consequently, cavitation noise can be reduced more effectively. In particular, in this embodiment, a gap is provided between the nozzle unit 12 (specifically, the mounting portion 46 and the second holder-side cylindrical portion 42) and the shielding body 14 in the radial direction, but no gap is provided between the nozzle unit 12 (specifically, the mounting portion 46) and the shielding body 14 in the direction of the central axis C1 (front-rear direction). Therefore, the shielding body 14 can vibrate in the radial direction, but it cannot vibrate in the direction of the central axis C1. Because the shielding body 14 cannot vibrate in the direction of the central axis C1, the distance between the outlet 54 and the shielding body 14 is kept constant, and the pressure inside the nozzle unit 12 can be stabilized.

[0040] Furthermore, as shown in Figure 4, in the front-rear direction along the central axis C1 of the nozzle unit 12, the holder-side disc portion 48 is located in front of the pressure reduction portion 30, the outlet 54 is located between the holder-side disc portion 48 and the main body-side disc portion 34, and the main body-side disc portion 34 is located behind the holder-side disc portion 48. The nozzle unit 12 further includes a second holder-side cylindrical portion 42 (an example of a "surrounding wall portion") that extends from the outer peripheral end of the holder-side disc portion 48 to the rear in the front-rear direction (an example of a "second side") and defines a first flow path (an example of a "flow path") between the first impact chamber 60 and the second impact chamber 64. The mounting portion 46 protrudes outward from the second holder-side cylindrical portion 42. When the shielding body 14 is attached to the mounting portion 46, the front end of the shielding body 14 is located behind the holder-side disc portion 48. With the above configuration, the length of the microbubble generating nozzle 10 in the front-to-back direction can be shortened compared to a configuration in which the front end of the shielding body 14 is located in front of the holder-side disc portion 48.

[0041] (Second example) The microbubble generating nozzle 210 of the second embodiment will be described with reference to Figures 9 to 12. In this embodiment, the configuration of the holder portion 222 differs from that of the holder portion 22 of the first embodiment. In the following, components common to both embodiments will be denoted by the same reference numerals and their descriptions will be omitted.

[0042] As shown in Figure 9, the microbubble generating nozzle 210 includes a nozzle unit 212. The nozzle unit 212 includes a nozzle body 20 and a holder portion 222. The holder portion 222 is made of resin. The holder portion 222 includes a first holder-side cylindrical portion 240, a second holder-side cylindrical portion 242 (see Figure 10), two connecting portions 244, and a holder-side disc portion 248. The first holder-side cylindrical portion 240, the second holder-side cylindrical portion 242 (see Figure 10), and the connecting portion 244 have substantially the same configuration as the first holder-side cylindrical portion 40 (see Figure 4), the second holder-side cylindrical portion 42 (see Figure 4), and the connecting portion 44 (see Figure 4) of the first embodiment, respectively, except that their lengths in the front-rear direction are different.

[0043] As shown in Figure 11, a projection 249 is provided in the central part of the holder-side disc portion 248, projecting backward. The projection end (rear end) of the projection 249 is located between the nozzle 30d of the decompression section 30 and the front end 36a of the second main body-side cylindrical portion 36. The first impact chamber 260 in this embodiment is the region between the rear surface 248a of the holder-side disc portion 248 and the front end 36a of the second main body-side cylindrical portion 36. The first impact chamber 260 is defined by the second holder-side cylindrical portion 242, the holder-side disc portion 248, and the projection 249. The second impact chamber 264 is the region between the rear end 242a of the second holder-side cylindrical portion 242 and the front surface 34b of the main body-side disc portion 34. The second impact chamber 264 is defined by the first holder-side cylindrical portion 240, the main body-side disc portion 34, and the second main body-side cylindrical portion 36. The microbubble generating nozzle 210 further includes a shielding body 250. The shielding body 250 extends radially outward from the outer circumferential surface of the holder-side disc portion 248. The shielding body 250 is integrally formed with the holder-side disc portion 248 and is made of resin. The shielding body 250 is positioned in the front-rear direction opposite to the outlet 54. The outer diameter of the shielding body 250 is the same as the outer diameter of the first holder-side cylindrical portion 240. The distance L2 between the rear surface 250a of the shielding body 250 and the outlet 54 is 1 mm. The distance L2 is preferably in the range of 0.5 mm to 2 mm. As shown in Figure 12, notches 250b are formed on both the left and right sides of the shielding body 250. When the microbubble generating nozzle 210 is viewed from the front, substantially the entirety of the four outlets 54 is covered by the shielding body 250. In the modified example, when the microbubble generating nozzle 210 is viewed from the front, the four outlets 54 may be completely covered by the shielding body 250.

[0044] As described above, as shown in Figure 11, the microbubble generating nozzle 210 comprises a nozzle unit 212 and a shielding body 250. The nozzle unit 212 includes an inlet 30a into which air-dissolved pressurized water flows in, a pressure reducing section 30 that reduces the pressure of the air-dissolved pressurized water flowing in from the inlet 30a, a first impact chamber 260 located downstream of the pressure reducing section 30 and having a holder-side disc portion 248 (an example of a "first impact wall") that changes the direction of the flow path of the air-dissolved pressurized water by impacting the air-dissolved pressurized water flowing in from the pressure reducing section 30, a second impact chamber 264 located downstream of the holder-side disc portion 248 and having a body-side disc portion 34 that changes the direction of the flow path of the air-dissolved pressurized water by impacting the air-dissolved pressurized water that has passed through the first impact chamber 260, and an outlet 54 through which the water that has passed through the second impact chamber 264 flows out. The shielding body 250 is positioned outside the nozzle unit 212, facing the outlet 54. With this configuration, the air-dissolved pressurized water flowing out from the outlet 54 of the nozzle unit 212 collides with the shielding body 250. Because the air-dissolved pressurized water collides with the shielding body 250, the overall pressure loss of the microbubble generating nozzle 210 increases. In this case, the pressure inside the nozzle unit 212 can be increased compared to a configuration in which the air-dissolved pressurized water flowing out from the outlet 54 of the nozzle unit 212 does not collide with the shielding body 250. Therefore, the negative pressure in areas with locally large negative pressure inside the nozzle unit 212 can be reduced. This makes it possible to suppress bubbles bursting inside the nozzle unit 212. Consequently, cavitation noise can be reduced.

[0045] Although each embodiment has been described in detail above, these are merely illustrative examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

[0046] (First Modification) In the above embodiment, pressurized water with dissolved air flows into the microbubble generation nozzle 10. In the modification, instead of pressurized water with dissolved air, pressurized water with dissolved gas may flow into the microbubble generation nozzle 10. With this configuration, the amount of microbubbles generated at the outlet can be increased by the pressurized water with dissolved gas passing through the microbubble generation nozzle 10. Examples of gases include carbon dioxide, oxygen, and hydrogen.

[0047] (Second modified example) The number of pressure reducing units 30 provided on the nozzle body 20 is not limited to two; it may be one or three or more.

[0048] (Third Embodiment) In the first embodiment, when the microbubble generating nozzle 10 is viewed from the front, the outlet 54 does not have to be completely covered by the shielding body 14. That is, when the microbubble generating nozzle 10 is viewed from the front, a part of the outlet 54 may be covered by the shielding body 14.

[0049] (Fourth modified example) In the first embodiment, the shielding body 14 may be provided in front of the first impact chamber 60.

[0050] (Fifth Modification) In the first embodiment, the shielding body 14 may be made of resin instead of an elastic material.

[0051] (Sixth Modification) In the first embodiment, there does not need to be a gap between the shielding body 14 and the mounting portion 46, and between the shielding body 14 and the second holder side cylindrical portion 42.

[0052] (Seventh Modification) In the first embodiment, the shielding body 14 may be attached to the outer surface of the second holder side cylindrical portion 42 by adhesive or the like. In this modification, the "mounting portion" can be omitted.

[0053] (Eighth Modification) In the first embodiment, the mounting portion 46 may protrude outward or forward from the outer surface of the holder-side disc portion 48. In this modification, the front end of the mounting portion 46 is located in front of the holder-side disc portion 48.

[0054] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of symbols]

[0055] 10: Microbubble generating nozzle 12: Nozzle Unit 14: Shield 20: Nozzle body 22: Holder part 30: Reduced pressure section 30a: Inlet 30b: Reduced diameter channel 30c: Expanded diameter channel 30d: spout 32: First main body side cylindrical part 34: Main body side disc section 34a:Protrusion 34b:Front 36: Second main body side cylindrical part 36a: Front end 40: First holder side cylindrical part 42: Second holder side cylindrical part 42a: Front end 44:Connection part 46: Mounting part 48: Holder-side disc portion 48a: Rear 48b:Front 49:Protruding part 50: Notch 52: Connection part 54: Outlet 60: 1st collision chamber 62: 1st waterway 64:Second collision chamber 66: 2nd waterway 70: Cylindrical section on the first shielding side 72: Second shield side cylindrical section 72a: Front end 74: Third shield side cylindrical part 74a: Rear end 76: recess 210: Microbubble generating nozzle 212: Nozzle Unit 222: Holder part 240: First holder side cylindrical part 242: Second holder side cylindrical part 242a: Front end 244 :Connection part 248: Holder-side disc portion 248a: Rear 249: Protrusion 250: Shield 250a: Rear 250b: Notch 260: 1st collision chamber 264:Second collision chamber B: Screw hole C1: Central axis C2: Central axis L1: distance L2: distance

Claims

1. A nozzle for generating microbubbles, Nozzle unit and Equipped with a shielding body, The nozzle unit described above is An inlet into which pressurized water containing dissolved gas flows in, A pressure reducing section for reducing the pressure of the gas-dissolved pressurized water flowing in from the inlet, wherein the gas-dissolved pressurized water flows through the pressure reducing section toward a first side in the central axis direction along the central axis of the nozzle unit, from a second side opposite to the first side, and the pressure reducing section, A first impact chamber is provided downstream of the pressure reduction section and has a first impact wall that changes the direction of the flow path of the gas-dissolved pressurized water by impacting the gas-dissolved pressurized water flowing in from the pressure reduction section, wherein the direction of the flow path of the gas-dissolved pressurized water is changed so that the gas-dissolved pressurized water flows from the first side to the second side by impacting the first impact wall, A second impact chamber is provided downstream of the first impact chamber and has a second impact wall that changes the direction of the flow path of the gas-dissolved pressurized water by impacting the gas-dissolved pressurized water that has passed through the first impact chamber, wherein the direction of the flow path of the gas-dissolved pressurized water is changed so that the gas-dissolved pressurized water flows from the second side to the first side by impacting the second impact wall, An outlet through which the gas-dissolved pressurized water that has passed through the second impact chamber flows out, comprising an outlet facing the second impact chamber in the central axis direction, The shielding body is a microbubble generating nozzle located outside the nozzle unit, facing the outlet.

2. In the central axis direction, the first collision wall is provided on the first side of the pressure reduction section. In the central axis direction, the second collision wall is provided on the second side opposite to the first side of the first collision wall. In the central axis direction, the outlet is provided between the first impact wall and the second impact wall. The microbubble generating nozzle according to claim 1, wherein the shielding body is provided between the first collision wall and the outlet in the central axis direction.

3. A nozzle for generating microbubbles, Nozzle unit and Equipped with a shielding body, The nozzle unit described above is An inlet into which pressurized water containing dissolved gas flows in, A pressure reducing unit for reducing the pressure of the gas-dissolved pressurized water flowing in from the aforementioned inlet, A first impact chamber is provided downstream of the aforementioned depressurization section and has a first impact wall that changes the direction of the flow path of the gas-dissolved pressurized water by impacting the gas-dissolved pressurized water flowing in from the depressurization section, A second impact chamber is provided downstream of the first impact chamber and has a second impact wall that changes the direction of the flow path of the gas-dissolved pressurized water when the gas-dissolved pressurized water that has passed through the first impact chamber collides with it, It comprises an outlet from which the gas-dissolved pressurized water that has passed through the second impact chamber flows out, The shielding body is positioned outside the nozzle unit, facing the outlet. The shielding body is a microbubble generating nozzle made of an elastic material.

4. The nozzle unit is equipped with a mounting portion for attaching the shielding body, The microbubble generating nozzle according to claim 3, wherein a gap is provided between the mounting portion and the shielding body when the shielding body is attached to the mounting portion.

5. In the central axis direction along the central axis of the nozzle unit, the first impact wall is provided on the first side of the pressure reduction section. In the central axis direction, the second collision wall is provided on the second side opposite to the first side of the first collision wall. In the central axis direction, the outlet is provided between the first impact wall and the second impact wall. The nozzle unit further, The first impact wall extends from its outer peripheral end to the second side in the direction of the central axis, and comprises a peripheral wall portion that defines a flow path between the first impact chamber and the second impact chamber. The aforementioned mounting portion protrudes outward from the surrounding wall portion, The microbubble generating nozzle according to claim 4, wherein, when the shielding body is attached to the mounting portion, the first end of the shielding body is located on the second side of the first collision wall.

6. A microbubble generating nozzle according to any one of claims 1 to 5, wherein, when the microbubble generating nozzle is viewed from the shielding side in the direction along the flow path axis of the flow path connecting the second collision wall and the outlet, the shielding completely covers the outlet.

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