Cleaning device applying micro-nano bubbles
By combining a water storage tank and a dissolved air tank, along with a closed loop of metal conductors and electrical control circuits, the problems of continuous air intake and water temperature regulation in the micro-nano bubble cleaning device are solved, enabling the continuous generation of micro-nano bubble water, improving user experience and cleaning effect, and avoiding the defects of cold water diluting bubbles.
Patent Information
- Application Number
- CN202511515093.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-22
- Publication Date
- 2025-12-23
AI Technical Summary
Existing micro-nano bubble cleaning devices cannot achieve continuous air intake, resulting in an intermittent cleaning process, poor user experience, and the introduction of cold water when adjusting the water temperature reduces the density of micro-nano bubbles, leading to insufficient cleaning effect and efficiency.
By using a water storage tank in conjunction with a dissolved air tank for cyclical operation, a closed loop is formed using metal conductors and electrical control circuits. Combined with a helical gear set and an elastic air cushion, micro-nano bubble water is continuously generated. No cold water needs to be added when adjusting the water temperature. The Peltier effect is used to control gas dissolution and water temperature, and the structure is simple and reliable.
It achieves continuous generation of micro-nano bubble water, improves user experience, enhances cleaning effect, avoids diluting bubbles with cold water, ensures cleaning efficiency, and has anti-interference capabilities.
Smart Images

Figure CN121178508A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of micro-nano bubbles, and more particularly to a cleaning device that utilizes micro-nano bubbles. Background Technology
[0002] With the continuous development of people's environmental awareness, micro- and nano-bubbles are increasingly being applied in various fields due to their unique properties. The super-strong oxidation effect that occurs when micro- and nano-bubbles burst can degrade pollutants that are difficult to oxidize and decompose in water under normal conditions. Therefore, micro- and nano-bubbles have many applications in the cleaning field, as the properties of these tiny bubbles enable them to effectively clean and remove dirt.
[0003] Micro- and nano-bubble technology also has certain applications in the field of skin cleansing. By introducing micro- and nano-bubble technology into cleansing products, the cleansing effect and penetration ability of these products can be improved, thereby enhancing the cleansing and skincare results.
[0004] However, existing micro-nano bubble cleansing devices connect an external water source to the cleansing device, pressurize it internally, and then spray it onto the face. The device stops working when the internal gas is exhausted and can only work again after it is refilled with gas, which cannot achieve continuous air intake. The cleansing process is also intermittent, resulting in a poor user experience. Furthermore, existing micro-nano bubble cleansing devices require the addition of cold water when adjusting the water temperature, but this reduces the density of micro-nano bubbles in the final water, leading to insufficient cleansing effect and efficiency. Summary of the Invention
[0005] Therefore, this invention was made in view of the above problems. This invention, through the cyclical operation of a water storage tank and a dissolved air tank, can continuously generate micro-nano bubble water. Users do not need to stop cleaning, saving time and improving the user's cleaning experience. The above objectives are achieved through the following technical solutions:
[0006] A cleaning device utilizing micro / nanobubbles includes a fixed shell, a controller, dissolved air tanks, a water storage tank, and a main outlet pipe. The dissolved air tanks and water storage tank are housed inside the fixed shell, while the controller is located on the outer surface of the fixed shell. The dissolved air tanks are arranged equidistantly in a ring inside the fixed shell, with one side of each tank connected to the water storage tank via a metal conductor. The bottom of each tank is connected to the water storage tank via a connecting pipe. The water storage tank is connected to the main outlet pipe via an outlet pipe. The main outlet pipe contains a turbine, a turntable, a helical gear set, a fixed rod, and a telescopic rod. Fixed inside the main outlet pipe, the turntable is fixed below the turbine via a rotating shaft. The helical gear set includes: helical gear 1, helical gear 2, helical gear 3, and helical gear 4. Helical gear 1 has a cavity inside and is coaxially set with the turntable via a connecting rod. Helical gear 2 is set on one side of the helical gear set, and helical gear 1 and helical gear 2 mesh with each other. Helical gear 3 is set in a ring at equal intervals on the side of the dissolved air tank, and helical gear 3 and helical gear 2 can be connected by a telescopic rod. Helical gear 4 is set at the bottom of the rotating column, and helical gear 3 and helical gear 4 mesh with each other.
[0007] Preferably, the dissolved gas tank includes: a water inlet pipe, an air pump, and the water inlet pipe and air pump are respectively installed on the top of the dissolved gas tank.
[0008] Preferably, the metal conductor has two ends made of different metal materials, with one end extending into the dissolved gas tank and the other end extending into the water storage tank; the electrical control circuit has its two ends connected to the two ends of the metal conductor respectively, forming a closed circuit.
[0009] Preferably, the connecting pipe is provided with a pressure valve, and the pressure valve is a one-way valve.
[0010] Preferably, the water storage tank is equipped with a limiting groove, a rotating column, an elastic air cushion, a pressure valve II, and a water outlet pipe. The limiting groove is arc-shaped and there are eight sets. Each set of limiting grooves is set at eight opening positions of the water storage tank. The rotating column is movably set on the side wall of the water storage tank through the limiting groove. The elastic air cushion is set in a ring at equal intervals on the arc surface on the side of the rotating column. The pressure valve II is set at the connection between the water outlet pipe and the water storage tank.
[0011] Preferably, the elastic air cushion contains a low-boiling-point liquid, and the four elastic air cushions in each group contain different types of liquids.
[0012] Preferably, the surface of the helical gear three opposite to the helical gear two is provided with a rectangular groove adapted to the telescopic rod.
[0013] Preferably, the number of helical gears two, three, and four is eight.
[0014] Preferably, both helical gear two and helical gear three are mounted inside the fixed housing via a fixing rod.
[0015] Preferably, the four interfaces connecting the water outlet pipe to the bottom of the water storage tank are provided with wedge-shaped grooves, and the vent pipe is provided at the point where the cross-sectional area of the wedge-shaped groove opening is the smallest.
[0016] The beneficial effects of this invention are as follows:
[0017] 1. This invention, through the cyclical operation of the water storage tank and the dissolved air tank, can continuously generate micro-nano bubble water, allowing users to clean without stopping, saving users time and improving the user's cleaning experience;
[0018] 2. This invention utilizes the combined operation of a metal conductor and an electronic control circuit. By forming a closed loop with the metal conductor and the electronic control circuit, the Peltier effect is used to cause the metal conductor at the dissolved gas tank end to absorb heat after being energized, thereby reducing the temperature of the accumulated water. The lower water temperature increases the gas saturation of the water, thus dissolving more gas. At the same time, the low-temperature water containing a large amount of dissolved gas flows into the water storage tank. Under the expansion of the elastic air cushion due to the gas pressure released by the temperature rise, it passes through the wedge groove and generates a large number of micro-nano bubbles, improving the cleaning effect. Moreover, this process does not require an additional power source, and the structure is simple and highly reliable.
[0019] 3. This invention, through the coordinated operation of helical gear set, rotating column, and elastic air cushion, eliminates the need to add cold water when adjusting the water temperature in the storage tank, thus avoiding the dilution of air bubbles by cold water. Therefore, it does not cause a reduction in the density of micro-nano air bubbles in the water, resulting in a good cleaning effect.
[0020] 4. This invention operates through multiple sets of dissolved gas tanks and wedge-shaped grooves in a cyclical manner. Even if a single structure fails, it will not affect the operation of the overall equipment and can continue to provide cleaning services. It has strong anti-interference capabilities. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the appearance of the present invention.
[0022] Figure 2 This is a schematic diagram of the interior of the fixed shell of the present invention.
[0023] Figure 3 This is a bottom view of the interior of the fixed shell of the present invention.
[0024] Figure 4 This is a cross-sectional view of the dissolved gas tank of the present invention.
[0025] Figure 5 This is a schematic diagram of the water storage tank of the present invention.
[0026] Figure 6 This is a schematic diagram of the rotating column of the present invention.
[0027] Figure 7 This is an exploded view of the main water outlet pipe and helical gear assembly of the present invention.
[0028] Figure 8This is a schematic diagram of the telescopic rod of the present invention.
[0029] The cleaning equipment structure shown in the figure includes:
[0030] 1. Fixed shell; 2. Controller; 3. Dissolved air tank; 31. Water inlet pipe; 32. Air pump; 33. Metal conductor; 34. Electrical control circuit; 35. Connecting pipe; 36. Pressure valve one; 4. Water storage tank; 41. Limiting groove; 42. Rotating column; 43. Elastic air cushion; 44. Water outlet pipe; 45. Pressure valve two; 46. Wedge groove; 47. Air guide pipe; 5. Main water outlet pipe; 51. Turbine; 52. Turntable; 53. Helical gear set; 531. Helical gear one; 532. Helical gear two; 533. Helical gear three; 534. Helical gear four; 54. Fixed rod; 55. Telescopic rod. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0032] like Figure 1 , Figure 2 As shown, a cleaning device using micro-nano bubbles includes: a fixed shell 1, a controller 2, a dissolved air tank 3, a water storage tank 4, and a main water outlet pipe 5.
[0033] The fixed shell 1 is a hollow rectangular body, used to house the dissolved gas tank 3, the water storage tank 4 and other components;
[0034] The controller 2 is fixedly mounted on the outer surface of the fixed housing 1; the controller 2 is used to control the operation of each mechanism;
[0035] The dissolved gas tank 3 has a hollow rectangular structure, and there are four of them, which are fixed inside the fixed shell 1 in a ring at equal intervals by connecting rods.
[0036] The dissolved air tank 3 includes: a water inlet pipe 31, an air pump 32, a metal conductor 33, an electrical control circuit 34, and a connecting pipe 35.
[0037] The water inlet pipe 31 is fixedly installed above the dissolved air tank 3 and extends upward through the upper surface of the fixed shell 1; the water inlet pipe 31 can be connected to a faucet or other water supply device; the water inlet pipe 31 is equipped with an electric control valve, and the electric control valve is electrically connected to the controller 2. The user can set the single water injection volume through the controller 2, and the electric control valve will automatically close according to the set value to realize quantitative water injection and avoid the dissolved air tank 3 having too much or too little water, which would affect the dissolved air effect;
[0038] The air pump 32 is fixedly installed on the upper surface of the dissolved gas tank 3. Its output volume can be adjusted by the controller 2. The gas injection volume can be adjusted according to cleaning needs (such as skin cleansing and item cleaning) to control the density of micro-nano bubbles.
[0039] The metal conductor 33 has different metal materials at its two ends, and one end of the metal conductor 33 extends into the dissolved gas tank 3, while the other end extends into the water storage tank 4 described below.
[0040] The electrical control circuit 34 has its two ends connected to the two ends of the metal conductor 33 respectively, thereby forming a closed circuit, and the electrical control circuit 34 can supply power to the metal conductor 33.
[0041] The electrical control circuit 34 is equipped with a current regulation module, which can adjust the power supply current through the controller 2, thereby controlling the intensity of the Peltier effect and achieving precise control of the cooling range of the dissolved gas tank 3 and the heating range of the water storage tank 4.
[0042] The connecting pipe 35 has one end connected to the bottom of the dissolved gas tank 3, and the other end extends into the water storage tank 4;
[0043] The pressure valve 36 is fixedly installed inside the connecting pipe 35, and the pressure valve 36 is a one-way valve. When the pressure inside the dissolved gas tank 3 reaches the threshold, the valve automatically opens to release water, ensuring that the gas is fully dissolved in the water to form high-concentration dissolved gas water.
[0044] The water storage tank 4 is a hollow rectangular structure with two openings through the side walls on each of its four sides. The water storage tank 4 is used to install a limiting groove 41, a rotating column 42, an elastic air cushion 43, a pressure valve 45, and a water outlet pipe 44.
[0045] The water storage tank 4 is confined at the junction of the lines connecting the four dissolved gas tanks 3 by the aforementioned metal conductor 33 and connecting pipe 35; the water storage tank 4 has heat-conducting columns inside its wall.
[0046] The limiting groove 41 is arc-shaped and consists of eight groups, each group containing three grooves. Each group of limiting grooves 41 is set at eight opening positions of the water storage tank 4, and the limiting grooves 41 in each group are arranged at equal intervals in the vertical direction.
[0047] The number of rotating columns 42 is eight, and they are respectively movably set on the side wall of the water storage tank 4 through the limiting grooves 41.
[0048] The number of elastic air cushions 43 is eight groups, each group contains four, and the elastic air cushions 43 in each group are fixedly arranged in a ring at equal intervals on the arc surface on the side of the rotating column 42.
[0049] The elastic air cushion 43 contains a low-boiling-point liquid, and the four elastic air cushions 43 in each group contain different types of liquids.
[0050] The rotating column 42 and the elastic air cushion 43 can seal the opening of the water storage tank 4, and due to the extensibility of the elastic air cushion 43, the water storage tank 4 can be sealed and the water inside will not overflow.
[0051] The water outlet pipe 44 has four ports at one end, all of which are connected to the bottom of the water storage tank 4, and the other end is connected to the main water outlet pipe 5 described below.
[0052] There are four pressure valves 45, which are fixedly installed at the bottom of the water storage tank 4 and at the connection point between the water outlet pipe 44 and the water storage tank 4. When the pressure inside the water storage tank 4 reaches the threshold, the valves automatically open to ensure that the water flows into the water outlet pipe 44 at high speed, providing the power basis for the subsequent negative pressure generated by the wedge groove 46.
[0053] The number of wedge-shaped grooves 46 is four, which are respectively fixedly installed inside the water outlet pipe 44 and at the four interfaces where the water outlet pipe 44 connects to the bottom of the water storage tank 4;
[0054] The cross-sectional area of the wedge-shaped groove 46 gradually increases along the direction of water flow, so that a stable negative pressure is generated when the water flows through it, ensuring that the air guide pipe 47 can effectively draw in air.
[0055] There are four air guide pipes 47. One end of each air guide pipe 47 is connected to the water outlet pipe 44 and is fixedly installed at the minimum cross-sectional area of the wedge groove 46. The other end is located inside the fixed shell 1.
[0056] The main water outlet pipe 5 is fixedly installed below and connected to the single interface of the water outlet pipe 44;
[0057] The lower end of the main water outlet pipe 5 is fixedly installed at the bottom of the fixed shell 1;
[0058] The main water outlet pipe 5 is equipped with: a turbine 51, a turntable 52, a helical gear set 53, a fixed rod 54, and a telescopic rod 55.
[0059] The turbine 51 is fixed inside the main water outlet pipe 5. The blades of the turbine 51 are streamlined and can rotate efficiently under the impact of water flow, providing a stable source for the power transmission of the subsequent helical gear set 53.
[0060] The turntable 52 is fixedly mounted below the turbine 51 via a rotating shaft and can be driven by the turbine 51; the turntable 52 is embedded in the pipe wall of the main water outlet pipe 5, and bearings are provided at the contact points with the main water outlet pipes 5 above and below it.
[0061] The helical gear set 53 includes: helical gear one 531, helical gear two 532, helical gear three 533, and helical gear four 534.
[0062] The helical gear 531 has a cavity inside and is coaxially arranged with the turntable 52 via a connecting rod (the turntable 52 is located at the center of the helical gear 531 and can drive the helical gear 531 to rotate).
[0063] The number of helical gears 532 is eight, which are respectively set inside the fixed shell 1 by the following fixing rods 54, and are arranged in pairs, equidistantly in a ring on the side of helical gear 531.
[0064] There are eight helical gears 533, which are respectively set inside the fixed shell 1 by the following fixing rods 54 and are arranged in a ring at equal intervals on the side of the dissolved gas tank 3; the helical gears 533 and the helical gears 532 are provided with rectangular grooves on their opposite surfaces.
[0065] Both helical gear 2 532 and helical gear 3 533 are inclined, and the helical gear 2 532 and helical gear 3 533 in each group are parallel to each other;
[0066] The number of helical gears 4534 is eight, and they are respectively set at the bottom of the rotating column 42;
[0067] The helical gear 1 531 and helical gear 2 532 mesh with each other, and the helical gear 3 533 and helical gear 4 534 mesh with each other;
[0068] The number of fixing rods 54 is multiple, and they are respectively arranged between the helical gear 2 532, the helical gear 3 533 and the bottom surface of the fixing shell 1;
[0069] The telescopic rods 55 are eight quadrangular prisms, each set on the second helical gear 532, and can be extended or shortened by the controller 2; when extended, the telescopic rods 55 can be inserted into the groove of the third helical gear 533, which can drive the gear to move synchronously.
[0070] Working principle of the invention
[0071] When this invention is used, the dissolved gas tanks 3 are arranged in pairs and operate cyclically. When the dissolved gas tanks 3 are working, the electric control valve in the water inlet pipe 31 is opened to inject water into the dissolved gas tanks 3 in a metered manner. After the metered water injection, the electric control valve is closed. The electric control circuit 34 operates to supply power to the metal conductor 33. Under the Peltier effect, the end of the metal conductor 33 in the dissolved gas tank 3 absorbs heat, which lowers the temperature of the water in the dissolved gas tank 3 and increases the gas saturation of the water, allowing more gas to be dissolved. At the same time, the air pump 32 operates to pressurize the dissolved gas tanks 3 so that the gas can be further dissolved into the water. When the air pump 32 pressurizes to the pressure threshold of the pressure valve 36, the pressure valve 36 opens. At this time, the low-temperature water containing a large amount of dissolved gas flows into the water storage tank 4 along the connecting pipe 35 to wait for the next step of the operation.
[0072] Because the metal conductor 33 inside the water tank 4 releases heat, and under the action of the heat-conducting column in the wall of the water tank 4, the water tank 4 is in a heated state. The liquid in the elastic air cushion 43 of the water tank 4 is heated and vaporized, causing the elastic air cushion 43 to be in an expanded state. As the water in the dissolved gas tank 3 flows in, it cools down the elastic air cushion 43 and causes the elastic air cushion 43 to return to its original position. Since the metal conductor 33 inside the water tank 4 is still in a heated state, the water in the water tank 4 is heated, which reduces the gas saturation of the water flow. The gas released increases the pressure inside the water tank 4. At the same time, the returned elastic air cushion 43 is heated and expands again, further increasing the pressure inside the water tank 4. When the pressure inside the water tank 4 reaches the pressure threshold of the pressure valve 45, the water flows out quickly from the four outlet pipes 44 under the action of pressure.
[0073] When the water flows through the outlet pipe 44, the wedge-shaped groove 46, which is narrow at the top and wide at the bottom, creates negative pressure during the flow, drawing air in through the air guide pipe 47 and mixing it with the water, thereby generating a large number of micro-nano bubbles. The resulting micro-nano bubble aqueous solution impacts the front end of the turbine 51 when it passes through the main outlet pipe 5, which helps to further mix with the air and increase the content of micro-nano bubbles in the water. Subsequently, the water flows out to the external water storage container and spray equipment to complete the subsequent cleaning work.
[0074] At this time, the working process between the two sets of dissolved air tanks 3 and water storage tank 4 is as follows: After the water in the first set of dissolved air tanks 3 is pressurized and cooled, it flows into the water storage tank 4 and the water outlet pipe 44 and is processed into micro-nano bubble aqueous solution before flowing out along the main water outlet pipe 5. Then the first set of dissolved air tanks treats the newly flowing water, while the water treated in the second set of dissolved air tanks 3 flows into the water storage tank 4 and cools the water storage tank 4 and the elastic air cushion 43. Then it is processed into micro-nano bubble aqueous solution. The above process is repeated, so as to continuously produce micro-nano bubble aqueous solution.
[0075] When the user needs to adjust the temperature of the subsequently produced micro-nano bubble aqueous solution, the extension rod 55 on the corresponding helical gear 2 532 can be controlled by the industrial control computer to extend and insert into the groove of the corresponding helical gear 3 533. In this way, when the water flows through the main outlet pipe 5, it drives the turbine 51, the turntable 52 and the helical gear 1 531 to rotate. Since the helical gear 1 531 and the helical gear 2 532 mesh with each other, and the helical gear 3 533 and the helical gear 4 534 mesh with each other, and at this time the states of the helical gear 2 532 and the helical gear 3 533 are connected and synchronized by the extension rod 55, the helical gear 4 534 and the rotating column 42 are driven to rotate. The liquid type in the elastic air cushion 43 in the water storage tank 4 changes, and the temperature when it reaches the collision state of the pressure threshold of the pressure valve 2 45 is adjusted, thereby causing the outlet water temperature of the water storage tank 4 to change accordingly.
Claims
1. A cleaning device using micro-nano bubbles, comprising a fixed shell (1), a controller (2), a dissolved air tank (3), a water storage tank (4), and a main water outlet pipe (5), wherein the dissolved air tank (3) and the water storage tank (4) are disposed inside the fixed shell (1), and the controller (2) is disposed on the outer surface of the fixed shell (1), characterized in that: The dissolved gas tanks (3) are arranged in a ring at equal intervals inside the fixed shell (1). One side of each dissolved gas tank (3) is connected to the water storage tank (4) through a metal conductor (33). The bottom end of the dissolved gas tank (3) is connected to the water storage tank (4) through a connecting pipe (35). The water storage tank (4) is connected to the main water outlet pipe (5) through a water outlet pipe (44). The main water outlet pipe (5) is equipped with: a turbine (51), a turntable (52), a helical gear set (53), a fixed rod (54), and a telescopic rod (55). The turbine (51) is fixed inside the main water outlet pipe (5). The turntable (52) is fixed below the turbine (51) through a rotating shaft. The helical gear set (53) includes: a helical gear one (5... 31) Helical gear 2 (532), helical gear 3 (533), and helical gear 4 (534). Helical gear 1 (531) has a cavity inside and is coaxially set with turntable (52) through connecting rod. Helical gear 2 (532) is set on the side of helical gear 1 (531), and helical gear 1 (531) and helical gear 2 (532) mesh with each other. Helical gear 3 (533) is set in a ring at equal intervals on the side of dissolved gas tank (3), and helical gear 3 (533) and helical gear 2 (532) can be connected by telescopic rod (55). Helical gear 4 (534) is set at the bottom of rotating column (42), and helical gear 3 (533) and helical gear 4 (534) mesh with each other.
2. The cleaning device using micro-nano bubbles according to claim 1, characterized in that: The dissolved gas tank (3) includes: a water inlet pipe (31) and an air pump (32). The water inlet pipe (31) and the air pump (32) are respectively located on the top of the dissolved gas tank (3).
3. A cleaning device using micro / nano bubbles according to claim 1, characterized in that: The metal conductor (33) has different metal materials at its two ends, and one end of the metal conductor (33) extends into the dissolved gas tank (3) and the other end extends into the water storage tank (4); the electrical control circuit (34) has its two ends connected to the two ends of the metal conductor (33) respectively, forming a closed circuit.
4. A cleaning device using micro / nano bubbles according to claim 1, characterized in that: The connecting pipe (35) is equipped with a pressure valve (36), and the pressure valve (36) is a one-way valve.
5. A cleaning device using micro / nano bubbles according to claim 1, characterized in that: The water storage tank (4) is used to set a limiting groove (41), a rotating column (42), an elastic air cushion (43), a pressure valve (45), and a water outlet pipe (44). The limiting groove (41) is arc-shaped and there are eight sets. Each set of limiting grooves (41) is set at eight opening positions of the water storage tank (4). The rotating column (42) is movably set on the side wall of the water storage tank (4) through the limiting groove (41). The elastic air cushion (43) is set in a ring at equal intervals on the arc surface on the side of the rotating column (42). The pressure valve (45) is set at the connection between the water outlet pipe (44) and the water storage tank (4).
6. A cleaning device using micro / nano bubbles according to claim 5, characterized in that: The elastic air cushion (43) contains a low-boiling-point liquid, and the four elastic air cushions (43) in each group contain different types of liquids.
7. A cleaning device using micro / nano bubbles according to claim 1, characterized in that: The helical gear three (533) and the helical gear two (532) have a rectangular groove on their opposite surfaces that is adapted to the telescopic rod (55).
8. A cleaning device using micro / nano bubbles according to claim 2, characterized in that: The number of helical gears 2 (532), 3 (533), and 4 (534) is eight each.
9. A cleaning device using micro / nano bubbles according to claim 2, characterized in that: Both helical gear two (532) and helical gear three (533) are set inside the fixed shell (1) by fixing rod (54).
10. A cleaning device using micro / nano bubbles according to claim 2, characterized in that: The water outlet pipe (44) is connected to the bottom of the water storage tank (4) at four interfaces with wedge-shaped grooves (46), and an air guide pipe (47) is provided at the smallest cross-sectional area of the wedge-shaped groove (46).
