Bubble generation device

Abstract

The present disclosure provides a bubble generation device capable of more efficiently generating fine bubbles in a liquid. A bubble generation device (100) according to the present disclosure causes liquid to pass therethrough and generates fine bubbles. The bubble generation device (100) comprises a rectification member (1) and an expansion flow path member (2). The rectification member (1) has a protruding part (11) that protrudes to the upstream side from a bottom surface part (13) that intersects a first direction (D1), and a liquid passage hole that is provided on the outer circumference of the protruding part (11) in the bottom surface part (13). The first direction (D1) is a direction in which the liquid passes. The expansion flow path member (2) has a flow path (21) that is provided on the downstream side of the rectification member (1) and in which the cross-sectional area orthogonal to the first direction (D1) increases from the upstream side toward the downstream side. A surface (111) on the upstream side of the protruding part (11) is configured by a curve in a cross section parallel to the first direction (D1).

Description

Bubble Generator

[0001] The present disclosure relates to a bubble generating device, and more particularly to a bubble generating device that generates fine bubbles by passing a liquid through it.

[0002] Patent Document 1 discloses a bubble generator. The bubble generator disclosed in Patent Document 1 includes a flow straightening member having a first cone portion protruding toward the upstream side of the liquid, and a downstream member provided downstream of the flow straightening member. The downstream member has an expanding diameter portion, which is a flow path whose cross-sectional area increases from upstream to downstream.

[0003] Japanese Patent Application Laid-Open No. 2021-30841

[0004] However, the bubble generating device of Patent Document 1 may not generate enough fine bubbles in the liquid.

[0005] An object of the present disclosure is to provide a bubble generating device that can generate fine bubbles in a liquid more efficiently.

[0006] A bubble generator according to one aspect of the present disclosure generates fine bubbles by passing a liquid through it. The bubble generator includes a flow straightening member and an extended flow path member. The flow straightening member has a bottom surface, a convex portion, and a liquid passage hole. The convex portion protrudes upstream from the bottom surface. The bottom surface intersects with a first direction, which is the direction in which the liquid passes. The liquid passage hole is provided on the outer periphery of the convex portion on the bottom surface. The extended flow path member is provided downstream of the flow straightening member and has a flow path whose cross-sectional area perpendicular to the first direction increases from the upstream side to the downstream side. The upstream surface of the convex portion is curved in a cross section parallel to the first direction.

[0007] A bubble generator according to another aspect of the present disclosure generates fine bubbles by passing a liquid through it. The bubble generator includes a flow straightening member and an expansion flow path member. The flow straightening member has a bottom surface, a convex portion, and a liquid passage hole. The convex portion protrudes upstream from the bottom surface. The bottom surface intersects with a first direction, which is a direction in which the liquid passes. The liquid passage hole is provided on the outer periphery of the convex portion on the bottom surface. The expansion flow path member is provided downstream of the flow straightening member and has a flow path whose cross-sectional area perpendicular to the first direction increases from the upstream side to the downstream side. The expansion flow path member has an inner circumferential surface, an upstream end face, and an inflow surface. The inner circumferential surface faces the flow path. The upstream end face has an opening corresponding to the upstream end of the flow path. The inflow surface is located between the inner circumferential surface and the upstream end face. The inflow surface has a shape in which the cross-sectional area of ​​the flow channel, which is perpendicular to the first direction and faces the inflow surface, narrows from the upstream side to the downstream side.

[0008] According to the bubble generation device according to one aspect of the present disclosure, fine bubbles can be generated in a liquid more efficiently.

[0009] FIG. 1 is a cross-sectional view of a bubble generator according to Embodiment 1. FIG. 2A is a perspective view of a flow straightening member of the bubble generator according to Embodiment 1. FIG. 2B is a plan view of the flow straightening member of the bubble generator according to Embodiment 1. FIG. 2C is a plan view of the flow straightening member of the bubble generator according to Embodiment 1, viewed from another direction. FIG. 3A is a perspective view of an extension flow path member of the bubble generator according to Embodiment 1. FIG. 3B is a plan view of an extension flow path member of the bubble generator according to Embodiment 1. FIG. 3C is a plan view of the extension flow path member of the bubble generator according to Embodiment 1, viewed from another direction. FIG. 4 is a cross-sectional view of a bubble generator according to a comparative example. FIG. 5 is a graph showing the flow velocities of liquids in Example, Comparative Example 1, and Comparative Example 2. FIG. 6 is a graph showing the number concentrations of ultra-fine bubbles in liquids in Example and Comparative Example 1. FIG. 7A is a cross-sectional view of a bubble generator according to Embodiment 2. FIG. 7B is a partially enlarged view of the bubble generator according to Embodiment 2. FIG. 8 is a partially enlarged view of the bubble generator according to Embodiment 1. Fig. 9 is a graph showing the relationship between the shape of the expansion flow path member and the pressure loss of the bubble generator. Fig. 10 is a cross-sectional view of a bubble generator according to embodiment 3. Fig. 11 is a cross-sectional view of a bubble generator according to embodiment 4. Fig. 12 is a cross-sectional view of a bubble generator according to embodiment 5. Fig. 13 is a cross-sectional view of a bubble generator according to embodiment 6.

[0010] Hereinafter, a bubble generating device according to an embodiment will be described in detail with reference to the drawings. However, each diagram described in the following embodiment is a schematic diagram, and the ratio of the size and thickness of each component does not necessarily reflect the actual dimensional ratio. Furthermore, the embodiment implemented below is merely one example of an embodiment of the present disclosure. The present disclosure is not limited to the following embodiment, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0011] (Embodiment 1) (1) Overview First, an overview of the bubble generator 100 according to Embodiment 1 will be described with reference to FIGS. 1 to 6. FIG. 1 is a cross-sectional view of the bubble generator 100 according to Embodiment 1. FIG. 2A is a perspective view of the flow straightening member 1 of the bubble generator 100. FIG. 2B is a plan view of the flow straightening member 1 of the bubble generator 100. FIG. 2C is a plan view of the flow straightening member 1 of the bubble generator 100, viewed from another direction. FIG. 3A is a perspective view of the expansion flow path member 2 of the bubble generator 100. FIG. 3B is a plan view of the expansion flow path member 2 of the bubble generator 100. FIG. 3C is a plan view of the expansion flow path member 2 of the bubble generator 100, viewed from another direction. FIG. 4 is a cross-sectional view of a bubble generator according to a comparative example. FIG. 5 is a graph showing the flow velocities of liquids in the example, comparative example 1, and comparative example 2. FIG. 6 is a graph showing the number concentrations of ultra-fine bubbles in the liquids of the example and comparative example 1.

[0012] The bubble generator 100 according to the first embodiment generates fine bubbles in a liquid by passing the liquid through it, thereby producing a bubble-containing liquid. In this embodiment, as an example, the bubble generator 100 uses tap water supplied from a waterworks system as the liquid and produces fine bubble water as the bubble-containing liquid. The bubbles contained in the liquid are called different names depending on their size. For example, bubbles with a diameter of 100 μm or less are called fine bubbles. Fine bubbles with a diameter of less than 1 μm are called ultrafine bubbles, and bubbles with a diameter of 1 μm or more are called microbubbles. In fine bubble water, the bubble surfaces are negatively charged, which allows them to adsorb positively charged substances, such as organic matter, and to act as surfactants. Furthermore, microbubble water can exhibit a sterilizing effect by incorporating, for example, highly oxidizing ozone into the bubbles. The bubble generator 100 can be installed, for example, in the piping between a shower head and a hose, or the piping between a washing machine's tub and water inlet.

[0013] As shown in Figures 1 to 3C, the bubble generator 100 according to the first embodiment includes a flow straightening member 1 and an expansion flow path member 2. The flow straightening member 1 has a bottom surface 13, a convex portion 11 protruding upstream from the bottom surface 13, and a plurality of (six in Figures 2A to 2C) liquid passage holes 12 provided on the outer periphery of the convex portion 11. The expansion flow path member 2 is provided downstream of the flow straightening member 1 and has a plurality of (four in Figures 3A to 3C) flow paths 21. The cross-sectional area of ​​the flow paths 21 increases from the upstream side to the downstream side. The flow velocity of the liquid supplied to the bubble generator 100 increases as it passes through the flow straightening member 1, and the pressure drop of the liquid increases at the inlets of the flow paths 21 in the expansion flow path member 2, enabling fine bubbles to be generated in the liquid more efficiently.

[0014] (2) Details Next, the details of the bubble generator 100 according to the first embodiment will be described with reference to FIGS. 1 to 6. In the following description, the direction in which the liquid flows in the bubble generator 100 is defined as a first direction D1, one direction perpendicular to the first direction D1 is defined as a second direction D2, and a direction perpendicular to the first direction D1 and the second direction D2 is defined as a third direction D3. However, these directions are not intended to limit the directions in which the bubble generator 100 is used. Furthermore, the arrows indicating "D1," "D2," and "D3" in the drawings are merely shown for the purpose of explanation and do not represent any actual substance.

[0015] FIG. 1 is a cross-sectional view of the bubble generation device 100 according to the first embodiment, with the third direction D3 as the normal direction, and liquid flows from bottom to top along the first direction D1.

[0016] 1 to 3C, the bubble generation device 100 according to the first embodiment includes a flow straightening member 1 and an expansion flow path member 2. The bubble generation device 100 according to the first embodiment is provided in a liquid flow path, such as a liquid supply member 3 (see FIG. 11), a water supply pipe, or a connection between a water supply pipe and a shower head.

[0017] 1 to 2C, the flow rectifying member 1 has a protrusion 11 and a liquid passage hole 12. The flow rectifying member 1 includes a cylindrical side surface portion 14 and a bottom surface portion 13.

[0018] The bottom surface portion 13 intersects with the first direction D1. The bottom surface portion 13 is, for example, disk-shaped and perpendicular to the first direction D1, and is provided with a convex portion 11 and a liquid passage hole 12, which will be described later. The side surface portion 14 is hollow and cylindrical, and protrudes upstream from the outer periphery of the bottom surface portion 13 along the first direction D1. A downstream surface 131 of the bottom surface portion 13 is, for example, a flat surface having an opening corresponding to the liquid passage hole 12, which will be described later.

[0019] A convex portion 11 is formed in the center on the upstream side of the bottom surface portion 13 of the flow straightening member 1. The convex portion 11 protrudes from the bottom surface portion 13 to the upstream side in the first direction D1. The upstream surface 111 of the convex portion 11 is configured as a curve in a cross section parallel to the first direction D1. In other words, the convex portion 11 does not include a vertex, which is a point where two sides intersect. More specifically, the convex portion 11 is hemispherical. Therefore, in a cross section of the flow straightening member 1 taken along a plane parallel to the first direction D1, the outline of the upstream surface 111 of the convex portion 11 is arc-shaped. In other words, the convex portion 11 has an arc-shaped circumferential surface in a cross section parallel to the first direction D1, which is the flow path direction of the liquid.

[0020] Here, the upstream surface 111 of the convex portion 11 refers to a continuous surface of the surface of the convex portion 11 other than the surface 131 that intersects with an imaginary line parallel to the first direction D1. In other words, the upstream surface 111 of the convex portion 11 may have a surface that is partially parallel to the first direction D1. In other words, in a cross section of the flow straightening member 1 taken along a plane parallel to the first direction D1, the contour line of the upstream surface 111 of the convex portion 11 may include a straight line in part.

[0021] Furthermore, a plurality of (six in FIGS. 2B and 2C ) liquid passage holes 12 are formed on the outer periphery of the convex portion 11 in the bottom surface portion 13 of the flow straightening member 1. Here, the outer periphery of the convex portion 11 refers to a region that does not overlap with the upstream surface 111 of the convex portion 11 in a plan view from the first direction D1.

[0022] Therefore, the liquid supplied from the upstream side of the flow straightening member 1 collides with the convex portion 11 and then passes through the liquid passage hole 12. As a result, the flow velocity of the liquid in the liquid passage hole 12 becomes sufficiently faster than the flow velocity on the upstream side of the flow straightening member 1.

[0023] (2.2) Expansion Flow Channel Member As shown in Figures 1 and 3A to 3C, the expansion flow channel member 2 has, for example, a cylindrical shape extending along the first direction D1. The expansion flow channel member 2 has a recess 23 at its upstream end in the first direction D1. As shown in Figure 1, the flow straightening member 1 is attached to the recess 23. In other words, the expansion flow channel member 2 is provided downstream of the flow straightening member 1.

[0024] The bottom surface of the recess 23 has an upstream end surface 241, an outer circumferential portion 242, and an inclined surface portion 243. The upstream end surface 241 is, for example, a circular region and has an opening corresponding to the flow path 21. The outer circumferential portion 242 is located upstream of the upstream end surface 241 in the first direction D1 and is, for example, ring-shaped. The upstream end surface 241 contacts the surface 131 of the bottom surface portion 13 of the flow rectifying member 1 when the flow rectifying member 1 is attached to the expansion flow path member 2. It is preferable that the upstream end surface 241 does not block the liquid passage holes 12 of the flow rectifying member 1 when the flow rectifying member 1 is attached to the expansion flow path member 2. The inclined surface portion 243 is provided between the upstream end surface 241 and the outer circumferential portion 242 and has a shape whose diameter decreases from the upstream side to the downstream side. Therefore, when the flow straightening member 1 is attached to the expansion flow path member 2, a space 26 exists between the bottom surface 13 of the flow straightening member 1 and the upstream end surface 241 of the expansion flow path member 2. Because the sloped surface 243 has the above-described structure, the space 26 has a shape in which the cross-sectional area perpendicular to the first direction D1 decreases from the upstream side to the downstream side. For example, the space 26 has a trapezoidal shape in a cross section parallel to the first direction D1.

[0025] The liquid passage hole 12 of the flow straightening member 1 is connected to the space 26. Liquid supplied to the bubble generator 100 flows from the liquid passage hole 12 of the flow straightening member 1 into the space 26 and then into the flow path 21 of the expansion flow path member 2. In the bubble generator 100, the presence of the space 26 makes it less likely that the portion between the liquid passage hole 12 of the flow straightening member 1 and the flow path 21 of the expansion flow path member 2 will become a bottleneck for the liquid flow. Therefore, in the bubble generator 100, it is possible to reduce pressure loss and increase the flow rate of the liquid. Furthermore, because the space 26 has a shape in which the cross-sectional area perpendicular to the first direction D1 decreases from the upstream side to the downstream side, the liquid that has passed through the liquid passage hole 12 of the flow straightening member 1 can easily flow into the flow path 21 of the expansion flow path member 2, making it possible to further reduce the occurrence of pressure loss.

[0026] The expansion flow path member 2 has a plurality of flow paths 21 (four in FIGS. 3A to 3C ). The expansion flow path member 2 has a plurality of inner circumferential surfaces 22 that face the plurality of flow paths 21, respectively. Each of the plurality of flow paths 21 extends in the first direction D1. Each of the plurality of flow paths 21 opens to an upstream end face 241, which is the bottom surface of the recess 23, and to a downstream end face 25 of the expansion flow path member 2. That is, each of the plurality of inner circumferential surfaces 22 is continuous with the upstream end face 241 and the end face 25. Each of the plurality of flow paths 21 has a shape in which the cross-sectional area in a direction perpendicular to the first direction D1 increases from the upstream side to the downstream side. That is, the cross-sectional area of ​​each of the plurality of flow paths 21 in a direction perpendicular to the first direction D1 decreases toward the upstream end face 241 and increases toward the end face 25. Each of the plurality of flow paths 21 has, for example, a truncated cone shape with its height in the first direction D1. Therefore, the liquid whose flow rate has been increased by the flow straightening member 1 is rapidly depressurized in the flow path 21, and gas (e.g., air) dissolved in the liquid precipitates as fine bubbles. This changes the liquid into a liquid containing fine bubbles. Furthermore, since the expansion flow path member 2 has multiple flow paths 21, it is possible to reduce pressure loss in the liquid and increase the flow rate of the liquid.

[0027] (3) Amount of bubbles generated Below, the flow rate of the liquid in the bubble generating device and the amount of bubbles in the bubble-containing liquid generated are evaluated for an example which is a bubble generating device according to embodiment 1 and comparative examples 1 and 2 which are bubble generating devices with different configurations.

[0028] The bubble generation device 900 of Comparative Example 1 includes a flow straightening member 8 and an expansion flow path member 9 as shown in FIG.

[0029] The flow straightening member 8 differs in configuration from the flow straightening member 1 in that the shape of the convex portion 81 is different from the shape of the convex portion 11. The convex portion 81 is, for example, a cone-shaped portion with its height direction aligned with the first direction D1 and its apex on the upstream side and its base on the downstream side. Therefore, in a cross section parallel to the first direction D1, the upstream surface 811 of the convex portion 81 is a V-shaped broken line, as shown in FIG. 4 , which includes straight lines and apexes but does not include curved lines.

[0030] The flow rectifying member 8 also has a plurality of liquid passage holes (not shown) on the outer periphery of the protrusion 81. The number of liquid passage holes in the flow rectifying member 8 is equal to the number of liquid passage holes 12 in the flow rectifying member 1. The cross-sectional area of ​​each of the plurality of liquid passage holes in the flow rectifying member 8 perpendicular to the first direction D1 is equal to the cross-sectional area of ​​each of the plurality of liquid passage holes 12 in the flow rectifying member 1 perpendicular to the first direction D1.

[0031] Similar to the expansion flow path member 2, the expansion flow path member 9 is provided downstream of the flow straightening member 8. More specifically, the flow straightening member 8 is provided in a recess 93 provided at the upstream end of the expansion flow path member 2 in the first direction D1. The bottom surface of the recess 93 of the expansion flow path member 9 has an upstream end face 941, an outer circumferential portion 942, and an inclined surface 943. The upstream end face 941 is, for example, a circular region and has an opening corresponding to the flow path 91. The outer circumferential portion 942 is located upstream of the upstream end face 941 in the first direction D1 and has, for example, a ring shape. The upstream end face 941 contacts the flow straightening member 8 when the flow straightening member 8 is attached to the expansion flow path member 9. Therefore, when the flow straightening member 8 is attached to the expansion flow path member 9, a space 96 exists between the upstream end face 941 of the expansion flow path member 9 and the bottom surface 83 of the flow straightening member 8 in the first direction D1.

[0032] The expansion flow path member 9 also has a plurality of flow paths 91. The expansion flow path member 9 has a plurality of inner circumferential surfaces 92 that face the plurality of flow paths 91, respectively. Each of the plurality of flow paths 91 extends in the first direction D1. Each of the plurality of flow paths 91 opens to an upstream end face 941 and a downstream end face 95. That is, each of the plurality of inner circumferential surfaces 92 is continuous with the upstream end face 941 and the end face 95. Each of the plurality of flow paths 91 has a shape in which the cross-sectional area perpendicular to the first direction D1 increases from the upstream side to the downstream side. Each of the plurality of flow paths 91 is, for example, a truncated cone shape with its height in the first direction D1. The number of flow paths 91 is equal to the number of flow paths 21 in the expansion flow path member 2. The shape and size of each of the plurality of flow paths 91 are equal to the shape and size of each of the plurality of flow paths 21.

[0033] The bubble generator (not shown) of Comparative Example 2 has a configuration in which the flow straightening member 8 is removed from the bubble generator 900 of Comparative Example 1, and includes an expansion flow path member 9 .

[0034] 5 is a graph comparing simulation results of the liquid flow velocity on the upstream side of the expanded flow path member 2 or the upstream side of the expanded flow path member 9 in Example, Comparative Example 1, and Comparative Example 2. In Example, the liquid flow velocity is the flow velocity at the end point of surface 111, i.e., the bottom surface of the hemispherical convex portion 11, and in Comparative Example 1, it is the flow velocity at the end point of surface 811, i.e., the bottom surface of the convex portion 81. The bottom surface here refers to the part of the convex portions 11 and 81 that is located most downstream of the liquid. In Comparative Example 2, the liquid flow velocity is the flow velocity at the same position as the end point of surface 811.

[0035] As shown in Fig. 5, the flow rate of the liquid is higher in the example including the flow straightening member 1 and in comparative example 1 including the flow straightening member 8 than in comparative example 2. That is, the flow straightening member 1 and the flow straightening member 8 have the effect of increasing the flow rate of the liquid. Furthermore, the flow rate of the liquid is higher in the example including the flow straightening member 1 than in comparative example 1 including the flow straightening member 8. That is, the flow straightening member 1 has a greater effect of increasing the flow rate of the liquid than the flow straightening member 8. As described above, the shape of the convex portions 81 of the flow straightening member 8 is different from the shape of the convex portions 11 of the flow straightening member 1. Therefore, it can be said that the fact that the flow straightening member 1 has a greater effect of increasing the flow rate of the liquid than the flow straightening member 8 is due to the difference between the shape of the convex portions 11 and the shape of the convex portions 81.

[0036] 6 is a graph showing the number concentration of fine bubbles (also referred to as particle number concentration) in the air-containing liquid after passing through the air bubble generator 100 and the air bubble generator 900 for each of Example and Comparative Example 1. Here, the liquid passed through the air bubble generator 100 and the air bubble generator 900 is water. The number concentration of fine bubbles in the air-containing liquid is the number of ultrafine bubbles per unit volume in the air-containing liquid, fine bubble water.

[0037] 6, the number concentration of ultra-fine bubbles generated by the bubble generator 100 of the example is approximately nine times higher than the number concentration generated by the bubble generator 900 of Comparative Example 1. That is, in the flow straightening member 1, the shape of the upstream surface 111 of the convex portion 11 is a shape in which the contour line along the plane parallel to the first direction D1 is composed of curves, which makes it possible to increase the number concentration of fine bubbles in the bubble-containing liquid.

[0038] (4) Effects The bubble generator 100 according to the first embodiment generates fine bubbles by passing a liquid through it. The bubble generator 100 includes a flow straightening member 1 and an expansion flow path member 2. The flow straightening member 1 has a convex portion 11 and a liquid passage hole 12. The convex portion 11 protrudes upstream from a bottom surface portion 13. The bottom surface portion 13 intersects with a first direction D1, which is the direction in which the liquid passes. The liquid passage hole 12 is provided on the outer periphery of the convex portion 11 on the bottom surface portion 13. The expansion flow path member 2 is provided downstream of the flow straightening member 1 and has a flow path 21. The cross-sectional area of ​​the flow path 21, perpendicular to the first direction D1, increases from the upstream side to the downstream side. The upstream surface 111 of the convex portion 11 is curved in a cross section parallel to the first direction D1. As a result, the liquid flowing into the bubble generator 100 collides with the convex portions 11 of the flow straightening member 1, and the flow rate of the liquid passing through the liquid passage holes 12 increases. Therefore, the flow rate of the liquid increases on the upstream side of the flow path 21 of the expansion flow path member 2, and the pressure drop of the liquid at the inlet of the flow path 21 increases, so that fine bubbles can be generated in the liquid more efficiently.

[0039] Furthermore, in the bubble generation device 100 according to embodiment 1, the convex portions 11 are hemispherical, which causes the liquid flowing into the bubble generation device 100 to collide with the convex portions 11 of the flow straightening member 1, further enhancing the effect of increasing the flow rate of the liquid passing through the liquid passage holes 12.

[0040] Furthermore, in the bubble generation device 100 according to the first embodiment, the expansion flow path member 2 has a plurality of flow paths 21 including the flow path 21. The cross-sectional area of ​​each of the plurality of flow paths 21, which is perpendicular to the first direction, increases from the upstream side to the downstream side. This increases the amount of liquid that can pass through the plurality of flow paths 21 per unit time, thereby reducing the pressure loss of the liquid and enabling an increase in the flow rate of the liquid.

[0041] Furthermore, the bubble generator 100 according to the first embodiment has a space 26 between the bottom surface 13 of the flow straightening member 1 and the upstream end surface 241 of the expansion flow path member 2. This reduces the occurrence of pressure loss between the liquid passage holes 12 of the flow straightening member 1 and the flow path 21 of the expansion flow path member 2, making it possible to increase the flow rate of liquid that can pass through the bubble generator 100.

[0042] Furthermore, in the bubble generation device 100 according to the first embodiment, the space 26 has a shape in which the cross-sectional area perpendicular to the first direction D1 decreases from the upstream side to the downstream side. This makes it easier for the liquid that has passed through the flow straightening member 1 to flow into the flow path 21 of the expansion flow path member 2, and makes it possible to further reduce the occurrence of pressure loss between the liquid passage hole 12 of the flow straightening member 1 and the flow path 21 of the expansion flow path member 2.

[0043] (Embodiment 2) Details of a bubble generator 200 according to embodiment 2 will be described with reference to Figures 7A to 9. Figure 7A is a cross-sectional view of the bubble generator 200 according to embodiment 2. Figure 7B is a partially enlarged view of the bubble generator 200. Figure 8 is a partially enlarged view of the bubble generator 100 according to embodiment 1. Figure 9 is a graph showing the relationship between the shape of the expansion flow path member 2a and the pressure loss of the bubble generator.

[0044] 7A, the bubble generator 200 according to the second embodiment includes a flow straightening member 1 and an expansion flow path member 2a. The flow straightening member 1 of the bubble generator 200 is the same as the flow straightening member 1 of the bubble generator 100 according to the first embodiment, and therefore, only the expansion flow path member 2a will be described below.

[0045] The expansion flow path member 2a differs from the expansion flow path member 2 in the structure of the connection portion between the upstream end face 241 and the inner circumferential surface 22. As shown in Figure 7B, the expansion flow path member 2a has an inlet surface 27 between the upstream end face 241 and the inner circumferential surface 22.

[0046] 7B , in a cross section parallel to the first direction D1, the inflow surface 27 is configured as an arc that protrudes toward the flow path 21. The shape of the inflow surface 27 is not limited to an arc, and may be a tapered surface such that the inflow port of the liquid in the flow path 21 narrows from upstream to downstream. In other words, the inflow surface 27 has a shape in which the cross-sectional area of ​​the portion of the flow path 21 facing the inflow surface 27, which is perpendicular to the first direction D1, narrows (becomes smaller) from the upstream side to the downstream side.

[0047] In contrast, in the expansion flow path member 2 according to the first embodiment, as shown in FIG. 8, the inflow surface 27 does not exist, and the upstream end surface 241 and the inner circumferential surface 22 are in direct contact with each other.

[0048] The expansion flow path member 2a has the same configuration as the expansion flow path member 2 of the bubble generation device 200 according to the first embodiment except that it has an inflow surface 27, and therefore the remaining description will be omitted.

[0049] (2) Change in Pressure Loss Figure 9 is a graph showing the results of a simulation of the relationship between the R dimension of the inflow surface 27, which is the shape of the expansion flow path member 2, and the pressure loss in the bubble generator 200. The R dimension indicates the radius of curvature when the cross section of the inflow surface 27 parallel to the first direction D1 is an arc-shaped section that protrudes toward the flow path 21. In Figure 9, the radius of curvature of the inflow surface 27 increases toward the right, and decreases toward the left. The position that overlaps the vertical axis indicates that the inflow surface 27 does not exist, and the upstream end surface 241 and the inner circumferential surface 22 are in direct contact with each other.

[0050] 8, when the inflow surface 27 is present, the pressure loss is lower than when the inflow surface 27 is not present. The reason for this is thought to be that the liquid flows more easily from the space 26 to the flow path 21, thereby reducing the pressure loss in the bubble generator 200. Therefore, compared to the bubble generator 100 of embodiment 1, the bubble generator 200 of embodiment 2 reduces the occurrence of pressure loss between the liquid passage hole 12 of the flow straightening member 1 and the flow path 21 of the expansion flow path member 2, and makes it possible to increase the flow rate of liquid that can pass through the bubble generator 200.

[0051] (3) Effects In the bubble generator 200 according to the second embodiment, the expansion flow path member 2a has an inner circumferential surface 22, an upstream end surface 241, and an inflow surface 27. The inner circumferential surface 22 faces the flow path 21. The upstream end surface 241 has an opening corresponding to the upstream end of the flow path 21. The inflow surface 27 is located between the inner circumferential surface 22 and the upstream end surface 241. The cross-sectional area of ​​the inflow surface 27, perpendicular to the first direction D1, of the portion of the flow path 21 facing the inflow surface 27 narrows from the upstream side to the downstream side. This facilitates the flow of liquid from the upstream side of the upstream end surface 241 of the expansion flow path member 2a into the flow path 21, thereby reducing pressure loss in the bubble generator 200. This reduces pressure loss between the liquid passage holes 12 of the flow straightening member 1 and the flow path 21 of the expansion flow path member 2a, making it possible to increase the flow rate of liquid that can pass through the bubble generator 200.

[0052] In the bubble generation device 200 according to the second embodiment, the inflow surface 27 is configured as an arc projecting toward the flow path 21 in a cross section parallel to the first direction D1. This makes it possible to further reduce the pressure loss of the bubble generation device 200 and increase the flow rate of liquid that can pass through the bubble generation device 200.

[0053] (Embodiment 3) Details of a bubble generation device 300 according to embodiment 3 will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view of the bubble generation device 300 according to embodiment 3.

[0054] (1) Configuration As shown in FIG. 10, the air bubble generation device 300 according to the third embodiment includes a flow straightening member 1a and an expansion flow path member 2a.

[0055] The flow straightening member 1a differs from the flow straightening member 1 of the bubble generation device 100 according to the first embodiment in the structure of the convex portions 11a. The convex portions 11a are conical in shape, with the height direction aligned with the first direction D1, the apex on the upstream side, and the base on the downstream side. Therefore, in a cross section of the flow straightening member 1a taken along a plane parallel to the first direction D1, the contour line of the upstream surface 111a of the convex portions 11a is V-shaped, as shown in FIG. 10 , and includes straight lines and a apex. The flow straightening member 1a has the same configuration as the flow straightening member 1 except for the convex portions 11a. The flow straightening member 1a has a liquid passage hole 12 (see FIGS. 2A to 2C ) on the outer periphery of the convex portions 11a on the bottom surface 13. That is, the flow straightening member 1a has the convex portions 11a protruding from the bottom surface 13 toward the upstream side of the liquid, and the liquid passage hole 12 provided on the outer periphery of the convex portions 11a on the bottom surface 13.

[0056] The expansion flow path member 2a is provided downstream of the flow straightening member 1a. The configuration of the expansion flow path member 2a is the same as that of the expansion flow path member 2a of the bubble generation device 300 according to the second embodiment. That is, the bottom surface of the recess 23 of the expansion flow path member 2a has an upstream end surface 241, an outer circumferential portion 242, and an inclined surface portion 243. The upstream end surface 241 is a circular region having an opening corresponding to the flow path 21 (see FIGS. 7A and 7B ). The outer circumferential portion 242 is located upstream of the upstream end surface 241 in the first direction D1 and has, for example, a ring shape. The upstream end surface 241 contacts the flow straightening member 1a when the flow straightening member 1a is attached to the expansion flow path member 2a. Therefore, when the straightening member 1a is attached to the expansion flow path member 2a, a space 26 exists between the upstream end face 241 of the expansion flow path member 2a and the bottom surface 13 of the straightening member 1a in the first direction D1.

[0057] The expansion flow path member 2a also has a plurality of flow paths 21. Each of the plurality of flow paths 21 extends in the first direction D1. Each of the plurality of flow paths 21 opens to an upstream end face 241 and a downstream end face 25. Each of the plurality of flow paths 21 has a shape in which the cross-sectional area perpendicular to the first direction D1 increases from the upstream side to the downstream side.

[0058] The expansion flow path member 2a also has an inflow surface 27 between the upstream end surface 241 and the inner circumferential surface 22 (see FIG. 7B ). The inflow surface 27 has a cross-sectional area, perpendicular to the first direction D1, of the flow path 21 that faces the inflow surface 27 and narrows from the upstream side to the downstream side. The cross-sectional shape of the inflow surface 27 along a plane parallel to the first direction D1 is an arc that protrudes toward the flow path 21.

[0059] As shown in Fig. 6 , the flow straightening member 8 of Comparative Example 1, which has convex portions 81 with a shape different from the convex portions 11 of the flow straightening member 1, has the effect of increasing the flow rate of the liquid. Therefore, similarly, the flow straightening member 1a, which has convex portions 11a with a shape different from the convex portions 11 of the flow straightening member 1, also has the effect of increasing the flow rate of the liquid. Furthermore, as shown in Fig. 9 , the expansion flow path member 2a has the effect of reducing the occurrence of pressure loss when the liquid passes through the inflow surface 27, compared to the expansion flow path member 2 of the bubble generation device 100 of Embodiment 1. Therefore, the bubble generation device 300 of Embodiment 3 has the effect of efficiently generating bubble-containing liquid by increasing the amount of liquid passing through.

[0060] (2) Effects The bubble generator 300 according to the third embodiment generates fine bubbles by passing a liquid through it. The bubble generator 300 includes a flow straightening member 1a and an expansion flow path member 2a. The flow straightening member 1a has a convex portion 11a and a liquid passage hole 12. The convex portion 11a protrudes upstream from a bottom surface portion 13. The bottom surface portion 13 intersects with the first direction D1. The liquid passage hole 12 is provided on the outer periphery of the convex portion 11a on the bottom surface portion 13. The expansion flow path member 2a is provided downstream of the flow straightening member 1a and has a flow path 21 whose cross-sectional area perpendicular to the first direction D1 increases from the upstream side to the downstream side. The expansion flow path member 2a has an inner circumferential surface 22, an upstream end surface 241, and an inlet surface 27. The inner circumferential surface 22 faces the flow path 21. The upstream end face 241 has an opening corresponding to the upstream end of the flow path 21. The inflow surface 27 is located between the inner circumferential surface 22 and the upstream end face 241. The inflow surface 27 has a shape in which the cross-sectional area of ​​the portion of the flow path 21 facing the inflow surface 27, perpendicular to the first direction D1, narrows from the upstream side toward the downstream side. This makes it easier for liquid to flow from the upstream side of the upstream end face 241 of the expansion flow path member 2 into the flow path 21, thereby reducing pressure loss in the bubble generation device 300. Therefore, it is possible to reduce pressure loss between the liquid passage hole 12 of the flow straightening member 1 and the flow path 21 of the expansion flow path member 2 and increase the flow rate of liquid that can pass through the bubble generation device 300.

[0061] In the bubble generation device 300 according to the third embodiment, the inflow surface 27 is configured as an arc projecting toward the flow path 21 in a cross section parallel to the first direction D1. This makes it possible to further reduce the pressure loss of the bubble generation device 200 and increase the flow rate of liquid that can pass through the bubble generation device 200.

[0062] (Fourth embodiment) Details of a bubble generation device 400 according to a fourth embodiment will be described with reference to Fig. 11. Fig. 11 is a cross-sectional view of the bubble generation device 400 according to the fourth embodiment.

[0063] (1) Configuration As shown in FIG. 11, the bubble generation device 400 according to the fourth embodiment includes a flow straightening member 1, an expansion flow path member 2, and a liquid supply member 3.

[0064] The liquid supply member 3 is, for example, a hollow cylindrical member extending in the first direction D1. The inner circumferential surface of the liquid supply member 3 is formed so that the expansion flow path member 2 can be stored in the liquid supply member 3. For example, the inner diameter of the liquid supply member 3 is formed to be the same as the outer diameter of the expansion flow path member 2. An upstream end 31 of the liquid supply member 3 is connected to a liquid supply mechanism (for example, a hose connected to a water faucet). A downstream end 32 of the liquid supply member 3 is connected to a device that uses the bubble-containing liquid (for example, a shower head, a washing machine tub, etc.).

[0065] The liquid supplied from the upstream end 31 of the liquid supply member 3 is supplied so as to collide with the convex portion 11 of the flow straightening member 1, and is supplied to the flow path 21 of the expansion flow path member 2 with its flow velocity increased by the liquid passage holes 12 of the flow straightening member 1. The bubble-containing liquid generated by the deposition of bubbles in the flow path 21 of the expansion flow path member 2 flows out from the end 32 of the liquid supply member 3. Therefore, the bubble generator 400 can be easily installed in a liquid flow path, for example, between a faucet and a tap, between a faucet and a shower head, or between the water stop valve and the washing tub of a washing machine.

[0066] In the bubble generator 400 according to the fourth embodiment, an expansion flow path member 2a (see FIG. 10) may be provided instead of the expansion flow path member 2. This allows the bubble generator 400 to be realized by combining the flow straightening member 1, the expansion flow path member 2a, and the liquid supply member 3. Furthermore, when the bubble generator 400 is provided with the expansion flow path member 2a, it may be provided with a flow straightening member 1a instead of the flow straightening member 1. This allows the bubble generator 400 to be realized by combining the flow straightening member 1a, the expansion flow path member 2a, and the liquid supply member 3.

[0067] (2) Effects The bubble generation device 400 according to the fourth embodiment further includes a liquid supply member 3 that supplies liquid to the flow straightening member 1. This makes it easy to install the bubble generation device 400 in a liquid flow path.

[0068] Fifth Embodiment Details of a bubble generation device 400a according to a fifth embodiment will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view of the bubble generation device 400a according to the fifth embodiment.

[0069] (1) Configuration As shown in Figure 12, the bubble generation device 400a of embodiment 5 has the same configuration as the bubble generation device 400 of embodiment 4, except that it includes an expansion flow path member 4 instead of the expansion flow path member 2 and the liquid supply member 3.

[0070] The expansion flow path member 4 is a member formed by integrally molding the liquid supply member 3 of the bubble generation device 400 according to embodiment 4 and the expansion flow path member 2 according to embodiment 1. That is, the expansion flow path member 4 serves as both the liquid supply member 3 and the expansion flow path member 2. An upstream end 41 of the expansion flow path member 4 is connected to a liquid supply mechanism. A downstream end 42 of the expansion flow path member 4 is connected to an apparatus that uses the bubble-containing liquid.

[0071] According to the bubble generator 400a of the fifth embodiment, it is not necessary to attach the expansion flow path member 2 to the liquid supply member 3, and therefore the bubble generator 400a can be easily assembled when manufactured. Furthermore, all of the liquid supplied to the bubble generator 400a from the end 41 of the expansion flow path member 4 is supplied to the flow straightening member 1, so the bubble generator 400a can efficiently generate bubble-containing liquid.

[0072] The expansion flow path member 4 may be a member in which the liquid supply member 3 and the expansion flow path member 2a are integrally molded. Furthermore, when the expansion flow path member 4 is a member in which the liquid supply member 3 and the expansion flow path member 2a are integrally molded, the bubble generation device 400a may include a flow rectifying member 1a instead of the flow rectifying member 1.

[0073] (2) Effects In the bubble generator 400a according to the fifth embodiment, the expansion flow path member 4 is formed integrally with the liquid supply member 3. This makes it easy to install the bubble generator 400a in a liquid flow path. Furthermore, the bubble generator 400a is easy to assemble.

[0074] Sixth Embodiment Details of a bubble generation device 100a according to a sixth embodiment will be described with reference to Fig. 13. Fig. 13 is a cross-sectional view of the bubble generation device 100a according to the sixth embodiment.

[0075] (1) Configuration As shown in FIG. 13, the air bubble generation device 100a according to the sixth embodiment has a communication hole 28 that connects the space 26 with the outside of the air bubble generation device 100a.

[0076] A first end of the communication hole 28 is provided, for example, in the inclined surface 243 of the expansion flow path member 2b. A second end of the communication hole 28 is provided in the outer surface of the expansion flow path member 2b.

[0077] When liquid is supplied to the bubble generation device 100a, the flow rate of the liquid in the space between the flow straightening member 1 and the expansion flow path member 2b is increased by the flow straightening member 1. In particular, the flow rate of the liquid in the space 26 is sufficiently increased by the flow straightening member 1. Therefore, the space 26 is under negative pressure relative to the outside of the bubble generation device 100a. Therefore, air flows into the space 26 from the outside of the bubble generation device 100a through the communication hole 28.

[0078] As a result, when liquid passes through the bubble generator 100a, in addition to the bubbles that precipitate in the liquid in the flow path 21 (see FIG. 1), the air that flows into the space 26 is included as bubbles in the bubble-containing liquid. The bubbles generated in the space 26 due to the air flowing in through the communication holes 28 are generated by air being sucked into the liquid, and are therefore larger than the bubbles generated by the precipitation of air dissolved in the liquid. Therefore, the bubble-containing liquid generated by the bubble generator 100a contains both fine bubbles and bubbles larger than fine bubbles. As a result, in the bubble-containing liquid generated by the bubble generator 100a, the fine bubbles and the bubbles larger than fine bubbles exhibit different or complementary effects, thereby enhancing the cleaning and sterilization effects, etc. For example, when the liquid is water, the bubble generator 100a can generate bubble water that contains millibubbles in addition to ultrafine bubbles and microbubbles.

[0079] (2) Effects The bubble generator 100a according to the sixth embodiment has a communication hole 28 that connects the space between the flow straightening member 1 and the expansion flow path member 2b with the outside of the bubble generator 100a. The communication hole 28 connects the space 26 with the outside of the bubble generator 100a. As a result, the bubble-containing liquid generated by the bubble generator 100a contains both fine bubbles and bubbles larger than fine bubbles. Therefore, the bubble-containing liquid generated by the bubble generator 100a has enhanced cleaning and sterilizing effects.

[0080] (Other variations of the embodiment) (1) In embodiment 1, the convex portion 11 of the straightening member 1 is hemispherical, but the convex portion 11 may have any shape as long as it protrudes upstream and the upstream surface 111 has a cross-sectional shape along the first direction D1 that does not include straight lines.

[0081] Similarly, although the convex portion 11a of the flow regulating member 1a is conical in the third embodiment, the convex portion 11a may have any shape as long as it protrudes upstream.

[0082] (2) In the bubble generation device 200 according to the second embodiment, the inflow surface 27 of the expansion flow path member 2a has a cross section parallel to the first direction D1 that is configured as an arc projecting toward the flow path 21. However, the cross-sectional area of ​​the portion of the flow path 21 that faces the inflow surface 27, which is perpendicular to the first direction D1, is not limited to the above-described shape as long as it narrows from the upstream side to the downstream side. For example, the inflow surface 27 may have a side surface shape of a truncated cone with the apex on the downstream side and the base on the upstream side.

[0083] (3) In the bubble generation device 100a according to the sixth embodiment, the expansion flow path member 2b may have an inflow surface 27 between the inner circumferential surface 22 and the upstream end surface 241, similar to the expansion flow path member 2a. That is, the second or third embodiment may be combined with the sixth embodiment.

[0084] (Aspects) A bubble generator (100; 100a; 200; 400; 400a) according to a first aspect generates fine bubbles by passing a liquid through it. The bubble generator (100; 100a; 200; 400; 400a) includes a flow straightening member (1) and an expansion flow path member (2; 2a; 4). The flow straightening member (1) has a bottom surface portion (13), a convex portion (11) protruding toward the upstream side of the liquid, and a liquid passage hole (12). The convex portion (11) protrudes toward the upstream side from the bottom surface portion (13). The bottom surface portion (13) intersects with a first direction (D1), which is the direction in which the liquid passes. The liquid passage hole (12) is provided on the bottom surface portion (13) around the outer periphery of the convex portion (11). The expansion flow path member (2; 2a; 4) is provided downstream of the straightening member (1) and has a flow path (21) whose cross-sectional area perpendicular to the first direction (D1) increases from the upstream side to the downstream side. The upstream surface (111) of the convex portion (11) is configured as a curve in a cross section parallel to the first direction (D1).

[0085] According to the bubble generation device (100; 100a; 200; 400; 400a) of the above aspect, the liquid flowing into the bubble generation device (100; 100a; 200; 400; 400a) collides with the convex portion (11) of the flow straightening member (1), increasing the flow velocity of the liquid passing through the liquid passage hole (12). Therefore, the flow velocity of the liquid increases on the upstream side of the flow path (21) of the expansion flow path member (2; 2a; 4), and the pressure drop of the liquid at the inlet of the flow path (21) increases, thereby increasing the efficiency of generating fine bubbles in the liquid.

[0086] In the air bubble generation device (100; 100a; 200; 400; 400a) according to the second aspect, the convex portion (11) is hemispherical in the first aspect.

[0087] According to the bubble generating device (100; 100a; 200; 400; 400a) of the above aspect, the liquid flowing into the bubble generating device (100; 100a; 200; 400; 400a) collides with the convex portion (11) of the straightening member (1), further enhancing the effect of increasing the flow rate of the liquid passing through the liquid passage hole (12).

[0088] In addition, in the bubble generation device (200; 400; 400a) according to the third aspect, in the first or second aspect, the expansion flow path member (2a; 4) has an inner circumferential surface (22), an upstream end surface (241), and an inflow surface (27). The inner circumferential surface (22) faces the flow path (21). The upstream end surface (241) has an opening corresponding to the upstream end of the flow path (21). The inflow surface (27) is located between the inner circumferential surface (22) and the upstream end surface (241). The inflow surface (27) has a cross-sectional area perpendicular to the first direction (D1) of the portion facing the inflow surface (27) of the flow path (21) that narrows from the upstream side toward the downstream side.

[0089] According to the bubble generator (200; 400; 400a) of the above aspect, the liquid can more easily flow from the upstream side of the upstream end face (241) of the extension flow path member (2a; 4) into the flow path (21), thereby reducing the pressure loss in the bubble generator (200; 400; 400a). Therefore, the pressure loss between the liquid passage hole (12) of the flow straightening member (1) and the flow path (21) of the extension flow path member (2a; 4) is reduced, and the flow rate of the liquid that can pass through the bubble generator (200; 400; 400a) can be increased.

[0090] A bubble generator (200; 300; 400; 400a) according to a fourth aspect generates fine bubbles by passing a liquid through it. The bubble generator (200; 300; 400; 400a) includes a flow straightening member (1; 1a) and an extension flow path member (2a; 4). The flow straightening member (1; 1a) has a bottom surface (13), a convex portion (11; 11a) protruding from the bottom surface (13) toward the upstream side of the liquid, and a liquid passage hole (12) provided radially outward of the convex portion (11; 11a). The extension flow path member (2a; 4) is provided downstream of the flow straightening member (1; 1a) and has a flow path (21) whose diameter increases from the upstream side to the downstream side. The extension flow path member (2a; 4) has an inner circumferential surface (22), an upstream end surface (241), and an inlet surface (27). The inner circumferential surface (22) faces the flow path (21). The upstream end face (241) has an opening corresponding to the upstream end of the flow path (21). The inflow surface (27) is located between the inner circumferential surface (22) and the upstream end face (241). The inflow surface (27) has a shape in which the cross-sectional area of ​​the portion of the flow path (21) facing the inflow surface (27) perpendicular to the first direction (D1) narrows from the upstream side toward the downstream side.

[0091] According to the bubble generator (200; 300; 400; 400a) of the above aspect, the liquid can easily flow from the upstream side of the upstream end face (241) of the extension flow path member (2a; 4) into the flow path (21), thereby reducing the pressure loss in the bubble generator (200; 300; 400; 400a). Therefore, it is possible to reduce the pressure loss between the liquid passage hole (12) of the flow straightening member (1; 1a) and the flow path (21) of the extension flow path member (2a; 4), and increase the flow rate of the liquid that can pass through the bubble generator (200; 400; 400a).

[0092] In addition, in the bubble generating device (200; 300; 400; 400a) relating to the fifth aspect, in the third or fourth aspect, the inlet surface (27) is configured as an arc protruding toward the flow path (21) in a cross section parallel to the first direction (D1).

[0093] According to the bubble generator (200; 300; 400; 400a) of the above aspect, it is possible to further reduce the pressure loss of the bubble generator (200; 300; 400; 400a) and increase the flow rate of liquid that can pass through the bubble generator (200; 300; 400; 400a).

[0094] Furthermore, the bubble generation device (400; 400a) according to the sixth aspect is any one of the first to fifth aspects, and further comprises a liquid supply member (3; 4) that supplies liquid to the rectifying member (1; 1a).

[0095] According to the bubble generation device (400; 400a) of the above aspect, it becomes easy to install the bubble generation device (400; 400a) in a liquid flow path.

[0096] In addition, in the bubble generator (400a) according to the seventh aspect, in the sixth aspect, the expansion flow path member (4) is formed integrally with the liquid supply member (3).

[0097] According to the air bubble generation device (400a) of the above aspect, the air bubble generation device (400a) can be easily assembled.

[0098] In the bubble generation device (100 to 400a) according to the eighth aspect, in any one of the first to seventh aspects, the expansion flow path member (2; 2a; 4) has a plurality of flow paths (21) including a flow path (21). Each of the plurality of flow paths (21) has a cross-sectional area perpendicular to the first direction (D1) that increases from the upstream side to the downstream side.

[0099] According to the bubble generating device (100 to 400a) of the above aspect, the amount of liquid that can pass through the multiple flow paths (21) per unit time increases, thereby reducing the pressure loss of the liquid and increasing the flow rate of the liquid.

[0100] In addition, the bubble generation device (100 to 400a) according to the ninth aspect, in any of the first to eighth aspects, has a space (26) between the bottom surface (13) of the straightening member (1; 1a) and an upstream end face (241) having an opening corresponding to the upstream end of the flow path (21) of the extension flow path member (2; 2a; 4).

[0101] According to the bubble generating device (100 to 400a) of the above aspect, it is possible to reduce the occurrence of pressure loss between the liquid passage hole (12) of the straightening member (1; 1a) and the flow path (21) of the expansion flow path member (2; 2a; 4), thereby increasing the flow rate of liquid that can pass through the bubble generating device (100 to 400a).

[0102] In addition, in the bubble generation device (100-400a) according to the tenth aspect, in the ninth aspect, the space portion (26) has a shape in which the cross-sectional area perpendicular to the first direction (D1) decreases from the upstream side to the downstream side.

[0103] According to the bubble generating device (100 to 400a) relating to the above-mentioned aspect, the liquid that has passed through the straightening member (1; 1a) can more easily flow into the flow path (21) of the expansion flow path member (2; 2a; 4), thereby making it possible to further reduce the occurrence of pressure loss between the straightening member (1; 1a) and the expansion flow path member (2; 2a; 4).

[0104] The bubble generation device (100a) according to the eleventh aspect is the ninth or tenth aspect, and further comprises a communication hole (28) that communicates the space (26) with the outside of the bubble generation device (100a).

[0105] According to the air bubble generator (100 to 400a) of the above aspect, in addition to fine bubbles resulting from the precipitation of gas dissolved in the liquid, air bubbles resulting from the air flowing in through the communication holes (28) are generated in the air-containing liquid. As a result, the air-containing liquid generated by the air bubble generator (100a) contains fine bubbles and bubbles larger than the fine bubbles. Therefore, the air-containing liquid generated by the air bubble generator (100a) has enhanced cleaning and sterilizing effects, etc.

[0106] 100, 100a, 200, 300, 400, 400a Bubble generator 1, 1a Flow straightening member 11, 11a Convex portion 111 Surface 12 Liquid passage hole 13 Bottom surface portion 2, 2a, 2b Extended flow path member 21 Flow path 22 Inner peripheral surface 241 Upstream end surface 26 Space portion 27 Inflow surface 28 Communication hole 3 Liquid supply member 4 Extended flow path member (liquid supply member) D1 First direction

Claims

1. A bubble generating device that generates fine bubbles by passing a liquid through it, comprising: a straightening member having a bottom surface that intersects with a first direction that is the direction in which the liquid passes, a convex portion that protrudes upstream from the bottom surface, and a liquid passage hole provided on the outer periphery of the convex portion in the bottom surface; and an extended flow path member that is provided downstream of the straightening member and has a flow path whose cross-sectional area perpendicular to the first direction increases from the upstream side to the downstream side, wherein the upstream surface of the convex portion is curved in a cross section parallel to the first direction.

2. The bubble generating device according to claim 1, wherein the convex portion is hemispherical.

3. The bubble generating device described in claim 1, wherein the expansion flow path member has an inner circumferential surface facing the flow path, an upstream end surface having an opening corresponding to the upstream end of the flow path, and an inflow surface located between the inner circumferential surface and the upstream end surface, and the inflow surface has a cross-sectional area perpendicular to the first direction of the portion of the flow path facing the inflow surface narrowing from the upstream side toward the downstream side.

4. A bubble generating device which generates fine bubbles by passing a liquid, comprising: a straightening member having a bottom surface portion which intersects with a first direction which is a direction in which the liquid passes, a convex portion protruding upstream from the bottom surface portion, and a liquid passage hole provided on the outer periphery of the convex portion on the bottom surface portion; and an extended flow path member which is provided downstream of the straightening member and has a flow path whose cross-sectional area perpendicular to the first direction increases from the upstream side to the downstream side, wherein the extended flow path member has an inner circumferential surface facing the flow path, an upstream end face having an opening corresponding to the upstream end of the flow path, and an inflow surface located between the inner circumferential surface and the upstream end face, wherein the cross-sectional area of ​​the inflow surface perpendicular to the first direction of a portion of the flow path which faces the inflow surface narrows from the upstream side to the downstream side.

5. A bubble generating device as described in claim 3 or 4, wherein the inflow surface is configured as a circular arc protruding toward the flow path in a cross section parallel to the first direction.

6. The bubble generating device according to any one of claims 1 to 4, further comprising a liquid supplying member that supplies the liquid to the straightening member.

7. The bubble generating device according to claim 6, wherein the expansion flow path member is formed integrally with the liquid supply member.

8. A bubble generating device as described in any one of claims 1 to 4, wherein the expansion flow path member has a plurality of flow paths including the flow path, and each of the plurality of flow paths has a cross-sectional area perpendicular to the first direction that increases from the upstream side to the downstream side.

9. A bubble generating device as described in any one of claims 1 to 4, having a space between the bottom surface of the straightening member and an upstream end surface having an opening corresponding to the upstream end of the flow path of the expansion flow path member.

10. The bubble generating device according to claim 9, wherein the space has a shape in which the cross-sectional area perpendicular to the first direction decreases from the upstream side to the downstream side.

11. The bubble generating device according to claim 9, further comprising a communication hole that connects the space with the outside of the bubble generating device.

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