JP2023059439A - Water flow generator - Google Patents

Abstract

To provide a water flow generator capable of successfully generating a water flow while avoiding an adverse effect on aquatic organisms.SOLUTION: A water flow generator 1 includes: a rotatable windmill 2; a cylindrical casing 11 inside of which is partitioned into an upper accommodation space and a lower accommodation space, the casing 11 including a lateral discharge port 19 communicated with the lower accommodation space; a rotating shaft extending vertically across the upper accommodation space and the lower accommodation space in the casing 11 and coupled to the windmill 2 to be rotatable coaxially with the windmill 2 along with the rotation of the windmill 2; a bearing accommodated in the upper accommodation space and supporting the rotating shaft 12 to be rotatable coaxially with the windmill 2; and an impeller 3 accommodated in the lower accommodation space and coupled to the rotating shaft 12 to be rotatable with the rotating shaft 12, the impeller 3 sending out water in the lower accommodation space from the discharge port 19 to outside of the casing 11 through the rotation.SELECTED DRAWING: Figure 2

Description

The present invention relates to a water flow generator that generates water flow.

When breeding aquatic organisms such as fish in a breeding container typified by aquariums such as ornamental aquariums (including ceramic water lily bowls, glass goldfish bowls, FRP aquariums, and Styrofoam bowls), oxygen must be supplied. As an aeration device for supplying oxygen to water, the device described in Patent Document 1 below is employed. The device described in US Pat. No. 5,800,000 includes an electrically driven bubble generator.

However, the place where the breeding container is installed is not limited to indoors. That is, there are cases where fish are reared outdoors in breeding containers. When the breeding container is installed outdoors, if the above air bubble generator is used as an aeration device, it is difficult to secure a power supply because there is no power outlet nearby, and even if a power supply can be secured, there is a risk of electric leakage. There's a problem. Therefore, development of an aeration device driven by natural force instead of electric power is being studied.

Patent Literature 2 below describes a wind water purifier that agitates water using wind power to supply oxygen to the water. The water flow generation unit of the wind water purifier described in Patent Document 2 includes a blade support rotated by a screw shaft to which rotational power from the wind turbine unit is transmitted, and blades protruding sideways from the outer periphery of the blade support. It has

Japanese Unexamined Patent Application Publication No. 2011-234638 JP 2013-000645 A

However, the wind water purification device described in Patent Document 2 is a relatively large device intended for installation in lakes and marshes. Since the blade protrudes laterally from the main body, even if the wind water purifier described in Patent Document 2 is downsized, the presence of the blade inevitably increases the size of the wind water purifier underwater. In particular, when such a device is installed in a container such as a water tank, the size of the device in the water becomes large in plan view, which narrows the habitat of the aquatic organisms, and there is a risk that the aquatic organisms cannot be nurtured satisfactorily. There is

In addition, since the blades are exposed in the above wind water purifier, when the rotating shaft rotates and the blades rotate, the rotating blades may hit aquatic organisms.

In any case, if an attempt is made to generate a water flow in the water in the breeding container using the wind water purifier described in Patent Document 2, there is a risk that aquatic organisms will be adversely affected. Therefore, it is required to generate good water flow while avoiding this adverse effect.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a water flow generator capable of generating good water flow while avoiding adverse effects on aquatic organisms.

One embodiment of the present invention is a water flow generating device for generating water flow in water, wherein a cylindrical upper housing space and a lower housing space partitioned from the upper housing space are partitioned inside. A cylindrical casing having a side wall formed with a discharge port communicating with the lower housing space, a rotatable windmill disposed above the casing, the upper housing space and the lower housing space. a rotating shaft that extends vertically across the wind turbine and is rotatable along with the rotation of the wind turbine; a bearing that is housed in the upper housing space and supports the rotating shaft so as to be rotatable about the same axis as the wind turbine; an impeller housed in a space and connected to the rotating shaft so as to be rotatable together with the rotating shaft, the impeller sending water inside the lower housing space out of the casing through the discharge port by rotation; A water flow generator is provided, comprising:

In one embodiment of the present invention, the water flow generator further includes a lower wall forming a lower surface of the lower housing space.

In one embodiment of the invention, a suction hole is formed in the central portion of the lower wall. Further, the suction hole may not be formed in the peripheral portion of the lower wall.

In one embodiment of the present invention, the water flow generator further includes a partition wall separating the upper accommodation space and the lower accommodation space. The lower wall and the partition wall are formed integrally with the impeller.

In plan view, the ejection direction of the ejection port may coincide with the tangential direction of the impeller. When the impeller includes a plurality of impeller blades, the plurality of impeller blades may be curved in the direction opposite to the rotational direction of the impeller. More specifically, the plurality of impeller blades may coincide with the curved direction of the wind turbine blades of the wind turbine.

According to this invention, the water taken into the lower housing space is swirled in the lower housing space by the rotation of the impeller and sent out of the casing through the discharge port. That is, the ejection port ejects water in a predetermined direction (for example, sideways). As a result, the water flow in the predetermined direction is formed around the water flow generator (the water flow in the predetermined direction is generated).

Since the impeller is rotated inside the casing and the swirling water is discharged from the discharge port to generate a water flow, the direction in which the water is sent out can be changed from the discharge port compared to the case where the impeller is exposed without providing a casing. It can be aggregated in the ejection direction (one or more directions). Thereby, the strength of the water flow can be increased in a desired direction. In addition, since the impeller is housed in the cylindrical casing, the outer diameter of the impeller does not become larger than the inner diameter of the casing. By setting the inner diameter of the casing to be small, it is possible to reduce the size of the apparatus in plan view in water, and as a result, the habitat area of aquatic organisms is not narrowed.

Moreover, since the impeller is housed in the casing, it is possible to suppress or prevent the rotating impeller from hitting aquatic organisms.

As a result, it is possible to favorably generate water flow while avoiding adverse effects on aquatic organisms.

FIG. 1 is a perspective view of a water flow generator according to one embodiment of the invention. FIG. 2 is a side view of the water flow generator. FIG. 3 is a plan view of the water flow generator. FIG. 4 is a vertical cross-sectional view of a water flow generation unit of the water flow generation device. FIG. 5 is a cross-sectional view of FIG. 4 as seen from the section line V-V.

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a water flow generator 1 according to one embodiment of the invention. FIG. 2 is a side view of the water flow generator 1. FIG.

The water flow generator 1 is a water flow generator for generating a water flow in water stored in a breeding container 100 typified by an aquarium such as an aquarium for viewing. Breeding container 100 is installed outdoors, for example. It is a water flow generating device for generating a water flow in the water stored in the rearing container 100 . Aquatic organisms such as ornamental fish such as killifish and goldfish are grown in the breeding container 100 .

As shown in FIGS. 1 and 2, the water flow generator 1 includes a rotatable windmill 2 on a water surface WF (see FIG. 2), and an impeller 3 (see FIG. 2) rotated by the rotational power of the windmill 2. A water flow generation unit 4 for generating a water flow in the water, and an attachment unit 5 for hooking and attaching to the side wall 101 of the rearing container 100. - 特許庁The water flow generator 1 may be attached to the side wall 101 by sandwiching the side wall 101 with the attachment unit 5, or may be attached to the side wall 101 using another jig.

The windmill 2 is arranged above the water flow generation unit 4 . With the water flow generator 1 attached to the side wall 101 (hooked on the upper end of the side wall 101) by the mounting unit 5, the wind turbine 2 is positioned above the water surface, and at least the lower portion of the water flow generation unit 4 is underwater. being immersed. Oxygen is supplied to the aquatic organisms reared in the breeding container 100 by generating a water flow in the water in the breeding container 100 by the water flow generator 1 .

FIG. 3 is a plan view of the water flow generator 1. FIG.

As shown in FIGS. 1 to 3, the wind turbine 2 includes a plurality of wind turbine blades 6, and blades that hold the plurality of wind turbine blades 6 from above and below so as to be rotationally symmetrical about a predetermined central axis C. holder. This blade holder includes an upper holder 7 that holds the plurality of wind turbine blades 6 from above and a lower holder 8 that holds the plurality of wind turbine blades 6 from below. The upper holder 7 has the shape of a downward cylindrical container. In the lower edge of the upper holder 7, notches (not shown) of the same number as the number of the wind turbine blades 6 are arranged at regular intervals in the circumferential direction. The lower holder 8 is in the shape of an upward cylindrical container. A bottom wall of the lower holder 8 is formed with a bolt hole vertically penetrating the bottom wall. A bolt is fixed to the upper end of the rotating shaft 12 through this bolt hole, thereby fixing the wind turbine 2 to the water flow generating unit 4 . In the upper edge of the lower holder 8, the same number of notches (not shown) as the number of the wind turbine blades 6 are arranged at regular intervals in the circumferential direction. A plurality of wind turbine blades 6 are held by the upper and lower holders 7 and 8 by fitting the upper and lower edges of the inner periphery of each wind turbine blade 6 into the notches of the upper and lower holders 7 and 8, respectively. An upper holder 7 and a plurality of wind turbine blades 6 are detachably attached to the lower holder 8 . Although the upper holder 7 can be omitted and a plurality of wind turbine blades 6 can be held only by the lower holder 8, by holding the upper holder 7 as well, the durability is increased and the upper end of the wind turbine blades 6 is protected. It also has the effect of reducing the risk of injury to the user.

As shown in FIG. 3, the windmill blade 6 is made of a resin material such as PVC. A plurality of wind turbine blades 6 have the same specifications. Each wind turbine blade 6 is a curved plate curved in a convex circular arc in a direction opposite to the rotation direction Dr1 of the wind turbine 2 in plan view. The wind turbine blades 6 are parallel to the central axis C of the wind turbine 2 in their entirety (each wind turbine blade 6 is a flat blade). The height dimension of the wind turbine blade 6 is, for example, approximately 100 mm. The outer diameter of the wind turbine 2 including the plurality of wind turbine blades 6 is, for example, approximately 176 mm.

FIG. 4 is a longitudinal sectional view of the water flow generation unit 4. As shown in FIG. FIG. 5 is a cross-sectional view of FIG. 4 as seen from the section line V-V. FIG. 4 is a cross-sectional view of FIG. 5 viewed from the section line IV-IV.

As shown in FIGS. 2 and 4, the water flow generating unit 4 includes a cylindrical casing 11, a rotating shaft 12 that extends vertically inside the casing 11 and rotates together with the rotation of the wind turbine 2, and the rotating shaft 12. , a rolling bearing 13 supporting the wind turbine 2 so as to be rotatable around the same axis, and an impeller unit 14 connected to the lower end of the rotating shaft 12 inside the cylindrical casing 11 so as to be rotatable together with the rotating shaft 12 . I have. When the wind turbine 2 rotates due to the wind in a state where the water flow generator 1 is attached to the side wall 101 (attached to the upper end portion) outdoors, the impeller 3 of the impeller unit 14 rotates accordingly. Water inside the tubular casing 11 is sent out of the casing 11 through a lateral discharge port 19 formed in the casing 11 , thereby forming a lateral water flow around the water flow generator 1 .

As shown in FIGS. 4 and 5, casing 11 is cylindrical. The casing 11 includes a cylindrical outer cylinder 15, a cylindrical inner cylinder 16 inserted through the outer cylinder 15 so as not to move and rotate in the axial direction with respect to the outer cylinder 15, and an upper opening 15a of the outer cylinder 15. and a lower cover 18 for closing the lower opening 15 b of the outer cylinder 15 . The height of casing 11 is, for example, approximately 150 mm, and the outer diameter of casing 11 is, for example, approximately 35 mm.

Outer cylinder 15 is formed using a metal material such as steel (for example, SUS). A communication port 50 is formed in the outer cylinder 15 at one position in the circumferential direction facing the side of the impeller 3 of the impeller unit 14 . A communication port 50 penetrates inside and outside of the outer cylinder 15 .

Casing 11 further includes discharge pipe 20 coupled to communication port 50 . The discharge pipe 20 extends laterally. A discharge port is formed at the tip of the discharge pipe 20 . The inside of the discharge pipe 20 communicates with the communication port 50 and the inside of the outer cylinder 15 . The discharge pipe 20 is formed using a metal material such as steel (for example, SUS).

The inner cylinder 16 is a member for supporting the rolling bearing 13, and the rolling bearing 13 is internally fitted and fixed. The inner cylinder 16 is formed using a resin material such as PVC. The inner cylinder 16 is fixed to the outer cylinder 15 using screws (not shown) or the like.

The upper cover 17 has the shape of a downwardly facing cylindrical container, and is made of a resin material such as polyamide or a metal material such as steel. The upper cover 17 is fitted onto the upper end of the outer cylinder 15 . An insertion hole 22 through which the rotating shaft 12 is inserted is formed in the central portion of the upper cover 17 .

The lower cover 18 is in the shape of an upward cylindrical container and is made of a resin material such as PVC. The lower cover 18 is fitted onto the lower end of the outer cylinder 15 . A central portion of the lower cover 18 is formed with a plurality of intake holes 23 for taking water from the lower portion of the casing 11 into the casing 11 . An intake tube 24 is attached to the intake hole 23 . The intake tube 24 is formed using a resin material such as acrylic resin. It is also possible to omit the intake tube 24 .

As shown in FIG. 4 , the rotating shaft 12 extends vertically inside the casing 11 and rotates together with the rotation of the wind turbine 2 . Rotating shaft 12 is formed using a metal material such as steel (for example, SUS). An impeller unit 14 is fixed to the lower end of the rotating shaft 12 . As will be described later, the interior of the casing 11 includes an upper accommodation space S1 and a lower accommodation space S2. The rotating shaft 12 extends vertically inside the casing 11 so as to straddle the upper housing space S<b>1 and the lower housing space S<b>2 and rotates together with the rotation of the wind turbine 2 .

Rolling bearing 13 includes rolling bearing 13A and rolling bearing 13B. The rolling bearings 13A and 13B are housed in the upper housing space S1 and support the rotating shaft 12 so as to be rotatable around the same axis as the wind turbine 2 . The rolling bearings 13A, 13B each have an inner ring 25, an outer ring 26, and a plurality of balls 27 arranged between the inner and outer rings 25, 26. As shown in FIG.

An inner peripheral surface 16a of the inner cylinder 16 is formed as a tapered surface. This tapered surface has the smallest diameter near the central portion and gradually increases in diameter toward the upper end or the lower end. The pair of rolling bearings 13A and 13B are arranged at a predetermined distance from each other in the axial direction of the rotating shaft 12 so as to sandwich the central portion of the inner peripheral surface 16a in the axial direction. Since the pair of rolling bearings 13A and 13B are arranged with an interval in the axial direction, the rotating shaft 12 can be satisfactorily held in a vertical position by the rolling bearings 13 .

Screws 29 and 30 are formed on the outer circumference of the rotary shaft 12 in regions other than the mounting positions of the rolling bearings 13A and 13B and between the rolling bearings 13A and 13B. A double nut 31 threadedly engaged with a screw 29 on the outer periphery of the rotary shaft 12 presses the rolling bearing 13A toward the central portion of the inner peripheral surface 16a. A double nut 32 threadedly engaged with a screw 30 on the outer periphery of the rotary shaft 12 presses the rolling bearing 13B toward the central portion of the inner peripheral surface 16a. As a result, the rolling bearings 13A and 13B are fixed to the mounting positions on the outer circumference of the rotating shaft 12 .

The rolling bearings 13A and 13B are so-called ceramic bearings. In the rolling bearings 13A, 13B, the plurality of balls 27 are made of ceramic, and the inner and outer rings 25, 26 are made of steel. Therefore, the torque of the rolling bearings 13A and 13B is reduced without using a lubricant. Therefore, even when only a light breeze is blowing and only a small rotational torque acts on the windmill 2, the rotating shaft 12 can be rotated.

As shown in FIGS. 4 and 5, the impeller unit 14 includes an impeller 3 connected to the rotary shaft 12 so as to rotate together, an upper wall plate (partition wall) 41, and a lower wall plate (lower wall) 42. I have. The impeller 3 has a plurality of impeller blades 43 . The upper wall plate 41 and the lower wall plate 42 are integrally formed with the impeller 3 . Therefore, compared with the case where each of the upper wall plate 41 and the lower wall plate 42 is formed of a member different from the impeller 3, the number of parts can be reduced.

The impeller 3 is formed using a metal material such as steel (for example, SUS) or a resin material such as PVC. The height of impeller 3 is, for example, about 15 mm, and the outer diameter of impeller 3 is, for example, about 28 mm.

The rotating shaft 12 is inserted through the impeller unit 14 . A threaded hole 44 formed in the upper wall plate 41 of the impeller unit 14 and a threaded hole 45 formed in the lower wall plate 42 are engaged with the screw 29 on the outer periphery of the rotary shaft 12, thereby allowing the impeller unit 14 to It is coupled to the rotary shaft 12 so as to be rotatable together.

The upper wall plate 41 of the impeller unit 14 forms the lower surface of the upper accommodation space S1 and the upper surface of the lower accommodation space S2. A lower wall plate 42 of the impeller unit 14 forms a lower surface of the lower housing space S2. That is, the upper wall plate 41 partitions the inside of the casing 11 into an upper housing space S1 that houses the rolling bearings 13A and 13B and the inner cylinder 16, and a lower housing space S2 that houses the impeller 3. As shown in FIG. A lower accommodation space S2 is defined by the upper wall plate 41, the lower wall plate 42, and the inner peripheral surface of the outer cylinder 15. As shown in FIG.

A plurality of suction holes 46 are formed in the central portion of the lower wall plate 42 for sucking the water taken into the casing 11 through the intake holes 23 into the lower housing space S2. The suction hole 46 is a small hole with a small diameter. The water taken inside the casing 11 is sucked into the lower housing space S2 through the plurality of suction holes 46 . This suction hole is not formed in the peripheral portion of the lower wall plate 42 .

The impeller 3 has a plurality of (for example, eight) impeller blades 43 . These multiple impeller blades 43 are rotationally symmetrical about the rotation axis 12 . As shown in FIG. 5, the multiple impeller blades 43 have the same specifications. Each impeller blade 43 is a curved plate curved in a convex circular arc in a direction opposite to the rotation direction Dr2 in plan view. Each impeller blade 43 extends parallel to the rotating shaft 12 over its entire area. As described below, the rotational direction Dr2 of the impeller 3 coincides with the rotational direction Dr1 of the wind turbine 2 in plan view, so the bending direction of the plurality of impeller blades 43 corresponds to the bending direction of the wind turbine blades 6 of the wind turbine 2. is consistent with

As shown in FIG. 5, the direction in which the discharge pipe 20 extends coincides with the tangential direction of the rotating impeller 3 in plan view. That is, the discharge direction of the discharge port 19 matches the tangential direction of the rotating impeller 3 .

With the water flow generator 1 attached to the side wall 101, when the wind turbine 2 rotates due to the wind, the wind turbine 2 rotates in the rotation direction Dr1 (see FIG. 3), and accompanying the rotation of the wind turbine 2, The impeller 3 rotates in the rotation direction Dr2 (see FIG. 5). As a result, the water inside the lower accommodation space S2 swirls in the lower accommodation space S2. Since the discharge direction of the discharge port 19 coincides with the tangential direction of the rotating impeller 3, the water swirling in the lower accommodation space S2 can be smoothly discharged from the discharge port 19. - 特許庁

In addition, since each impeller blade 43 is curved in a convex arc shape in a direction opposite to the rotation direction Dr2 in plan view, the impeller 3 can be rotated without generating a large load torque. This allows the impeller 3 to rotate smoothly even when a low torque acts on the rotating shaft 12 .

Further, water is sucked into the lower accommodation space S2 through the plurality of suction holes 46 by the rotation of the impeller 3 . Specifically, water is taken into the casing 11, and the water is sucked into the lower housing space S2 through the suction hole 46. As shown in FIG. Since the suction hole 46 is a small hole, even if foreign substances such as algae and moss are contained in the water taken into the casing 11, these foreign substances can pass through the suction hole 46 into the lower housing space S2. You can prevent being sucked in. If foreign substances such as algae and moss enter the lower housing space S2, they may become entangled with the impeller blades 43 and the wall plates 41 and 42, and hinder the smooth rotation of the impeller 3. However, since it is possible to suppress the foreign matter from being sucked into the lower housing space S2, it is possible to prevent rotation failure of the impeller 3 caused by the entry of the foreign matter.

Also, when the impeller 3 is rotating, the foreign matter contained in the water taken into the casing 11 receives the centrifugal force of the rotation of the impeller 3 (impeller unit 14), and the peripheral edge of the lower wall plate 42 The lower wall plate 42 moves toward the central portion of the lower wall plate 42 with difficulty. Since the plurality of suction holes 46 are formed in the central portion of the lower wall plate 42, it is possible to more effectively prevent these foreign substances from being sucked into the lower housing space S2 through the suction holes 46.

As described above, according to this embodiment, the water inside the lower housing space S<b>2 is swirled in the lower housing space S<b>2 by the rotation of the impeller 3 and is sent out of the casing 11 through the discharge port 19 . As a result, a lateral water flow is formed around the water flow generator 1 .

Since the water swirled by rotating the impeller 3 inside the casing 11 is discharged from the discharge port 19 to generate a water flow, the direction in which the water is sent out can be changed as compared with the case where the impeller 3 is exposed without providing the casing 11. , discharge direction (one or more directions) from the discharge port 19 . Thereby, the strength of the water flow can be increased in a desired direction. Further, since the impeller 3 is housed inside the cylindrical casing 11 , the outer diameter of the impeller 3 does not become larger than the inner diameter of the casing 11 . By setting the inner diameter of the casing 11 to be small, it is possible to reduce the size of the water flow generator 1 in water in plan view, and as a result, the habitat area of aquatic organisms is not narrowed.

Moreover, since the impeller 3 is accommodated in the casing 11, it is possible to suppress or prevent the rotating impeller 3 from hitting aquatic organisms.

As a result, it is possible to favorably generate water flow while avoiding adverse effects on aquatic organisms.

Although one embodiment of the present invention has been described above, the present invention can be implemented in other forms.

For example, as the rolling bearings 13A and 13B, ceramic bearings in which the balls 27 are made of ceramic are used, but any low-torque bearing that rotates at low torque can be used instead.

Further, the number of wind turbine blades 6 included in the wind turbine 2 may be other than four.

Also, the number of impeller blades 43 included in the impeller 3 may be other than eight.

Moreover, although the impeller blades 43 were described as extending parallel to the rotation axis 12 over the entire area, they may be inclined with respect to the rotation axis 12 .

In addition, although the impeller blades 43 are described as being curved in the rotational direction Dr2 in plan view, the impeller blades 43 do not curve in the rotational direction Dr2 in plan view and extend radially in a flat plate shape. good too.

Moreover, each of the upper wall plate 41 and the lower wall plate 42 may be formed of a member different from the impeller 3 . In this case, the upper wall plate 41 and the lower wall plate 42 are not rotatable with the rotation of the impeller 3 and are fixed to the outer cylinder 15 .

Further, although the case where only one ejection port 19 is formed has been described as an example, a plurality of ejection ports 19 may be formed. Specifically, the casing 11 is formed with a plurality of discharge ports (discharge ports 19) arranged at intervals in the circumferential direction. It may be discharged from the outlet 19 .

Moreover, although the case where a plurality of suction holes 46 each formed of a small hole is formed as the suction hole has been described as an example, the suction hole may be configured by a plurality of arc-shaped holes.

Also, the breeding container 100 may be installed indoors instead of outdoors. The windmill 2 can rotate indoors as long as it is well ventilated.

Also, in the breeding container 100, cultured fish such as yellowtail, red sea bream, and greater amberjack may be raised instead of ornamental fish.

Reference Signs List 1: Water flow generator 2: Windmill 3: Impeller 11: Casing 12: Rotating shaft 13: Rolling bearing 19: Discharge port 41: Upper wall plate (partition wall)
42: Lower wall plate (lower wall)
46: Suction hole S1: Upper accommodation space S2: Lower accommodation space

Claims (4)

A water flow generator for generating a water flow in water,
rotatable windmills,
A cylindrical casing having a cylindrical upper housing space and a lower housing space partitioned from the upper housing space, the casing having a discharge port communicating with the lower housing space, and comprising the wind turbine. a casing positioned below the
a rotary shaft extending vertically across the upper housing space and the lower housing space inside the casing, and connected to the windmill so as to be rotatable about the same axis as the windmill as the windmill rotates;
a bearing housed in the upper housing space and supporting the rotating shaft so as to be rotatable around the same axis as the wind turbine;
An impeller housed in the lower housing space and connected to the rotating shaft so as to be rotatable together with the rotating shaft, wherein the rotation causes water inside the lower housing space to flow out of the casing through the discharge port. and a pumping impeller. The water flow generator according to claim 1, further comprising a lower wall forming a lower surface of the lower housing space. 3. The water flow generator according to claim 2, wherein a suction hole is formed in the central portion of said lower wall. further comprising a partition wall separating the upper accommodation space and the lower accommodation space;
The water flow generator according to claim 2 or 3, wherein said lower wall and said partition wall are integrally formed with said impeller.

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