Patent Publication Number: US-2023136866-A1

Title: Air-flow channel structure of air pump, micro air pump, waterproof air pump, and inflatable product

Description:
CROSS REFERENCE TO THE RELATED APPLICATIONS 
     This application is based upon and claims priority to Chinese Patent Application No. 202122624337.8, filed on Oct. 29, 2021; 202122624319.X, filed on Oct. 29, 2021; 202221038806.6, filed on Apr. 28, 2022, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to the technical field of air pumps, particularly to an air-flow channel structure of an air pump, a micro air pump, a waterproof air pump, and an inflatable product. 
     BACKGROUND 
     An air pump is a device used to remove air from or add air to an enclosed space. At present, various inflatable products, such as inflatable mattresses, inflatable trampolines, inflatable sofas, inflatable toys, inflatable boats, inflatable swim rings, inflatable pools, and others, usually use outer air pumps for rapid inflation or aspiration. For outdoor use, it is not convenient for the user to bring an air pump to use, but manual inflation is laborious and time-consuming. Based on the above-mentioned problems, the prior art has provided an inflatable product with a built-in air pump. 
     An air pump realizes the pumping function by driving the impeller to rotate through an electric motor. The closed impeller in the prior art is equipped with a cover on both sides of the impeller blade, which has a high inflating efficiency, but the manufacturing process is complicated and costly and requires ultrasonic welding of the upper cover. The open impeller in the prior art has no cover on one side of the impeller blade, which can be made by a simple manufacturing process that is less costly and does not require ultrasonic welding, but the inflating efficiency is not as high as that of the closed impeller. In addition, the air pump in the prior art is limited by the impeller structure, requiring additional air-guiding pieces. A utility model patent (Chinese patent No. 201921542896.0) discloses that an electric inflator pump includes a ventilation seat. The ventilation seat is provided with a circle of airflow inlets in the circumferential direction of the ventilation seat. The bottom face of the ventilation seat is provided with a plurality of guide grooves, and the guide grooves communicate with the airflow inlets in a one-to-one correspondence. It is required to set the ventilation seat to achieve air-guiding, which has a complicated structure with many parts. Thus, the overall size of the pump cannot be manufactured to be small. Additionally, it also has drawbacks, such as loud noises, high energy consumption, and low inflating efficiency per unit volume. Therefore, the air pump in the prior art is limited by some factors, such as volume, inflating efficiency, and the like, and cannot be built into small-sized inflatable products, such as an inflatable swim ring. 
     In addition, in terms of inflatable products that contact water, such as inflatable boats, inflatable swim rings, inflatable pools, and the like, the air pump must be waterproof. If sealing and waterproofing are not sufficient, electric leakage may occur and cause safety hazards. Additionally, the existing built-in air pump can only be used with the inflatable product it is built into rather than being separable from the inflatable product, which does not facilitate charging and maintaining the air pump. Thus, once the air pump is damaged, the inflatable product is discarded simultaneously with the damaged air pump, which limits its use and flexibility. Besides, the existing air pump generally has a complex structure and a cumbersome production process. 
     SUMMARY 
     The main objective of the present invention is to overcome the shortcomings of the prior art and provide an air-flow channel structure of an air pump, a micro air pump, a waterproof air pump, and an inflatable product. The air-flow channel structure of the air pump speeds up the flowing of the air and improves the inflating efficiency. It reduces the overall size of the air pump when it is applied in the micro air pump, which meets the requirement for a built-in air pump for small inflatable products. It is convenient to assemble and disassemble the waterproof air pump to facilitate charging, repairing, replacing, and flexibly using the air pump. 
     The technical solutions in the present invention are as follows. 
     An air-flow channel structure of an air pump includes a shell body and a centrifugal impeller. The shell body is formed with an air chamber which is configured for accommodating the centrifugal impeller. The centrifugal impeller is arranged inside the air chamber. The air chamber is provided with an air inlet arranged along an axial direction of the centrifugal impeller. The air inlet communicates with an axial-direction air inlet of the centrifugal impeller. The air chamber is formed with an air-guiding wall inside that gradually expands in a spiral shape around an axis of the centrifugal impeller. A gap is provided between the air-guiding wall and the centrifugal impeller, and the gap forms an air-guiding channel. The air-guiding wall is gradually away from the centrifugal impeller from the head end of the air-guiding channel to the tail end of the air-guiding channel. The air chamber is provided with a tangent air outlet at the tail end of the air-guiding channel. The tangent air outlet communicates with the air-guiding channel and an exterior part of the air chamber. Air flows to the axial-direction air inlet of the centrifugal impeller from the air inlet. The centrifugal impeller radially blows air, and the air flows from the head end of the air-guiding channel to the tail end of the air-guiding channel and flows out of the air chamber from the tangent air outlet. 
     Further, the shell body includes an impeller mounting seat and an impeller cover. The impeller mounting seat and the impeller cover are sealingly connected. The air chamber is formed between the impeller mounting seat and the impeller cover. The air inlet is arranged on the impeller cover. The impeller mounting seat is provided with a bottom baffle. The air-guiding wall is connected onto the bottom baffle. 
     Further, the centrifugal impeller includes an upper cover board, a lower cover board, and a plurality of impeller blades that are connected between the upper cover board and the lower cover board. The external diameter of the lower cover board is shorter than the external diameter of the upper cover board. 
     Further, the external diameter of the lower cover board of the centrifugal impeller is not greater than the diameter of the axial-direction air inlet. 
     Further, a side, facing towards the axial-direction air inlet of the centrifugal impeller, of the air inlet extends downwards to form an extending edge. A side, facing towards the air inlet, of the axial-direction air inlet of the centrifugal impeller extends upwards to form a ring boss. The extending edge protrudes into the ring boss. 
     Further, the upper cover board is obliquely arranged gradually upwards from an outer side to an inner side radially. The impeller blades extend to the center shaft from an edge of an outer side of the upper cover board to an inner side and extend upwards to protrude into the ring boss. The upper end surfaces of the impeller blades gradually go upwards obliquely along with the upper cover board, where the impeller blades are located in a section from an edge of an outer side of the upper cover board to the ring boss. The upper end surfaces of the impeller blades gradually go downwards obliquely, where the impeller blades are located in a section from the ring boss to the center shaft. 
     Further, an air deflecting board is arranged above the tangent air outlet. The air deflecting boards are obliquely arranged from the top to the bottom along with the direction of air flowing out. 
     Further, the impeller cover is provided with a step that matches an outline of the air-guiding wall. The surface of the step has a flared shape that concaves from the outer circumference toward the center. 
     A micro air pump includes the air-flow channel structure of the air pump. 
     Further, the micro air pump further includes an air pump exterior shell and an electric motor. The electric motor is connected to and drives the centrifugal impeller to rotate. The shell body is provided in the air pump exterior shell or is a part of the air pump exterior shell. The air pump exterior shell is provided with a first air inlet and a first air outlet. One end of the air inlet of the air chamber communicates with the first air inlet of the air pump exterior shell, and the tangent air outlet communicates with the first air outlet of the air pump exterior shell. 
     Further, the micro air pump is further provided with a ventilating hole, and the ventilating hole is configured to communicate with the first air outlet and the outside and to provide an air inlet/outlet channel. 
     Further, the impeller mounting seat is provided with the ventilating hole on the exterior side of the air-guiding wall. 
     Further, the impeller cover extends upwards to form an air inlet sidewall at the air inlet, and the air inlet sidewall is provided with the ventilating hole. 
     Further, the electric motor is a coreless electric motor. 
     Further, the air pump exterior shell includes an air pump lower shell and an air pump upper cover. The first air inlet is provided on the air pump upper cover. The first air outlet is arranged on the air pump lower shell. The shell body is provided inside the air pump exterior shell. The air pump lower shell, the air pump upper cover, and the impeller mounting seat are removably assembled with each other in a limiting and clamping manner. The impeller mounting seat and the impeller cover are removably assembled with each other in the limiting and clamping manner. 
     Further, the micro air pump further includes a circuit board. The circuit board is electrically connected to the electric motor. The upper end of the impeller cover is formed with a circuit board mounting frame. The circuit board is position-limited and clamped on the circuit board mounting frame. A gap for the air to flow in is positioned between the circuit board and the air inlet of the impeller cover. 
     Further, the micro air pump is an inflator pump or an aspirator pump. 
     A waterproof air pump includes a waterproof exterior shell and the micro air pump removably connected to the waterproof exterior shell inside. The waterproof exterior shell includes a lower shell body and a waterproof upper cover. The lower shell body is removably connected to and relatively sealed with the waterproof upper cover. The micro air pump is removably connected to the lower shell body. The lower shell body is formed with a second air outlet. The second air outlet communicates with the first air outlet of the micro air pump. 
     Further, the lower shell body is connected to or fastened with the waterproof upper cover by a thread or a screw fastening assembly. The lower shell body is also connected to or fastened with the micro air pump by a thread or a screw fastening assembly. 
     An inflatable product includes the inflatable product body and the waterproof air pump. The exterior wall of the lower shell body is sealingly connected to the inflatable product body. The second air outlet is located in an interior cavity of the inflatable product body. The waterproof upper cover is exposed on an exterior part of the inflatable product body. 
     Based on the above description of the present invention and compared with the prior art, the advantages of the present invention are as follows. 
     Firstly, the air-flow channel structure of the air pump in the present invention is provided with the air-guiding wall that gradually expands in a spiral shape around the axis of the centrifugal impeller, which forms the increasingly wider air-guiding channel. The head end of the air-guiding channel blocks the circular flow of airflow and guides the air blown out radially from the centrifugal impeller to flow along the air-guiding channel. Under the guidance of the air-guiding channel, most of the air can flow out of the air chamber from the tangent air outlet located at the tail end of the air-guiding channel. Therefore, the airflows are guided more smoothly, the flowing speed of the air is faster, and the inflating/aspirating efficiency is higher. In addition, by arranging the oblique air deflecting board above the tangent air outlet, performances concerning guiding and gathering the air have been improved, and the airflows are guided to flow out of the air chamber from the tangent air outlet more smoothly and efficiently. The flow of the air is further speeded up, and the inflating/aspirating efficiency is further improved. 
     Secondly, the external diameter of the lower cover board of the centrifugal impeller is shorter than the diameter of the upper cover board, so compared to open impellers, the centrifugal impeller in the present invention configures airflow along a preset path better to improve the inflating/aspirating efficiency. Meanwhile, the external diameter of the lower cover board of the centrifugal impeller is no greater than the diameter of the axial-direction air inlet, which can be integrally molded using molds without the requirements of additional welding or bonding processes to simplify the manufacturing process and economize on costs. Furthermore, compared to closed impellers, the centrifugal impeller in the present invention is more convenient to process and manufacture with a lower cost. 
     Thirdly, in the present invention, an air-guiding channel is formed by the centrifugal impeller fitted with the air-guiding wall, and the air-flow channel structure is compact to reduce the overall size of the micro air pump. In addition, since the coreless electric motor has the advantages of being lightweight and small in size and having low energy consumption, a fast response, a small fluctuation of rotating speed, and low noise levels, the present invention uses a coreless electric motor in the air pump to further reduce the overall size of the micro air pump and make it more portable so that the micro air pump can achieve an inflating/aspirating efficiency that cannot be achieved by an air pump with an electric motor of the same power based on such a small size and can meet the requirements of a built-in air pump for small inflatable products. 
     Fourth, the side, facing towards the axial-direction air inlet of the centrifugal impeller, of the air inlet of the air chamber extends downwards to form the extending edge. The side, facing towards the air inlet of the air chamber, of the axial-direction air inlet of the centrifugal impeller extends upwards to form the ring boss. The extending edge protrudes into the ring boss. As a result, the air entering the air inlet can be directly guided into an interior part of the air chamber and into the centrifugal impeller to avoid air leaving the air chamber caused by the air leakage from a side of the air inlet of the centrifugal impeller when the air enters the air inlet of the centrifugal impeller and to enhance air-intaking pressure. 
     The surface of the step of the impeller cover forms the flared shape that concaves from the outer circumference towards the center, which benefits the process of guiding the air to the centrifugal impeller. 
     The upper cover board on the impeller blades is obliquely arranged gradually upwards from an outer side to an inner side radially. The impeller blades extend to the center shaft from an edge of an outer side of the upper cover board to an inner side and extend upwards to protrude into the ring boss. The upper end surfaces of the impeller blades gradually go upwards obliquely along with the upper cover board, where the impeller blades are located in a section from an edge of an outer side of the upper cover board to the ring boss. The upper end surfaces of the impeller blades gradually go downwards obliquely, where the impeller blades are located in a section from the ring boss to the center shaft. The above oblique structure facilitates the guiding of the air. Specifically, after air enters from the axial-direction air inlet of the impeller, it can flow rapidly downward under the guidance of the impeller blades that are located in a downwards oblique section of an interior side of the ring boss and then flow out radially from the centrifugal impeller. The air is prevented from leaving the axial-direction air inlet of the impeller, and the effective flow of air is accelerated. 
     Fifth, the ventilating hole is arranged and configured to provide an air inlet/outlet channel. In an inflating process of the air pump, when the inflatable product reaches an air-saturated state, and the air pump is not turned off in time resulting in the inflatable product continuing inflating, it may cause the inflatable product to burst due to over-saturation. Thus, by arranging the ventilating hole, the present invention enables excessive air to exit from the ventilating hole under air pressure, avoiding damage to the inflatable product caused by not turning off the air pump in time. In an aspirating process of the air pump, when the air inside the inflatable product has been all pumped out and the air pump is not turned off in time resulting in continued pumping of the inflatable product, the air inlet may be blocked and damage to the electric motor and the circuit board may occur due to the increase in temperature. At this time, a small amount of air can enter through the ventilating hole to maintain the pumping circulation, avoiding damage to the motor and the circuit board. 
     Sixth, the micro air pump is provided with the air pump lower shell and the air pump upper cover. The air inlet is provided on the air pump upper cover; the air outlet is arranged on the air pump lower shell. The circuit board is arranged beneath the air pump upper cover through the circuit board mounting frame. The arrangements facilitate arranging a control panel on the air pump upper cover, and the air pump upper cover is exposed outside when the micro air pump is arranged inside the inflatable product. It is convenient to control and facilitate air flowing in. Additionally, the air pump lower shell, the air pump upper cover, the impeller mounting seat, and the impeller cover are removably assembled with each other in a limiting and clamping manner, which simplifies the production process, improves the efficiency of product assembling, and facilitates maintenance and parts replacement. 
     Seventh, in the waterproof air pump of the present invention, the lower shell body and the waterproof upper cover are sealingly connected, achieving effective waterproofing and anti-air leakage. The micro air pump can be disassembled and separated integrally from the waterproof exterior shell, which facilitates charging, maintenance, and replacement of the micro air pump. One micro air pump can be configured with a plurality of inflatable products to use and inflate various inflatable products by connecting an air nozzle, which makes the micro air pump flexible and convenient to use and reduces costs. Meanwhile, thread connection, screw fastening connection, and other quick connection methods are adopted to connect the lower shell body with the waterproof upper cover and connect the micro air pump with the lower shell body, such that it is convenient and quick to assemble and disassemble, the connection between parts is stable, and the manufacturing difficulties are reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view showing a partial structure of a micro air pump according to Embodiment I of the present invention. 
         FIG.  2    is an exploded view of the micro air pump according to Embodiment I of the present invention. 
         FIG.  3    is a perspective view showing a mounting structure of an impeller mounting seat and a centrifugal impeller according to Embodiment I of the present invention. 
         FIG.  4    is a top view showing the mounting structure of the impeller mounting seat and the centrifugal impeller according to Embodiment I of the present invention. 
         FIG.  5    is a perspective view showing a structure of an impeller cover according to Embodiment I of the present invention. 
         FIG.  6    is a cross-sectional view of the micro air pump according to Embodiment I of the present invention. 
         FIG.  7    is a perspective view of the centrifugal impeller according to Embodiment I of the present invention at a first angle of view. 
         FIG.  8    is a perspective view of the centrifugal impeller according to Embodiment I of the present invention at a second angle of view. 
         FIG.  9    is a cross-sectional view of the centrifugal impeller according to Embodiment I of the present invention. 
         FIG.  10    is a cutaway view of a micro air pump according to Embodiment II of the present invention. 
         FIG.  11    is a perspective view showing a partial structure of the micro air pump according to Embodiment II of the present invention. 
         FIG.  12    is a perspective view showing a mounting structure of a micro air pump according to Embodiment III of the present invention at a first angle of view. 
         FIG.  13    is an exploded view of the micro air pump according to Embodiment III of the present invention. 
         FIG.  14    is an exploded view showing a centrifugal impeller, an impeller mounting seat, and an impeller cover in the micro air pump according to Embodiment III of the present invention. 
         FIG.  15    is a cross-sectional view showing a partial structure of the micro air pump according to Embodiment III of the present invention. 
         FIG.  16    is a perspective view of the centrifugal impeller and the impeller mounting seat in an assembled state according to Embodiment III of the present invention. 
         FIG.  17    is a perspective view of the impeller mounting seat according to Embodiment III of the present invention. 
         FIG.  18    is a perspective view of an air pump upper cover according to Embodiment III of the present invention. 
         FIG.  19    is a perspective view showing a mounting structure of an air pump lower shell and an electric motor locking plate according to Embodiment III of the present invention. 
         FIG.  20    is a perspective view of a partial structure of the micro air pump according to Embodiment III of the present invention, showing a mounting structure of a circuit board and a circuit board mounting frame and a mounting structure of the impeller mounting seat and the air pump lower shell. 
         FIG.  21    is a perspective view showing an overall structure of a waterproof air pump according to Embodiment III of the present invention. 
         FIG.  22    is an exploded view of the waterproof air pump according to Embodiment III of the present invention. 
         FIG.  23    is a cross-sectional view of the waterproof air pump according to Embodiment III of the present invention. 
         FIG.  24    is an exploded view of a partial structure of the waterproof air pump according to Embodiment III of the present invention. 
         FIG.  25    is a perspective view showing the mounting structure of the micro air pump according to Embodiment III of the present invention at a second angle of view. 
         FIG.  26    is a cross-sectional view of the lower shell body according to Embodiment III of the present invention. 
         FIG.  27    is a perspective view of an inflatable swim ring according to Embodiment III of the present invention. 
         FIG.  28    is a perspective view of a waterproof air pump according to Embodiment IV of the present invention. 
         FIG.  29    is a perspective view of a waterproof upper cover according to Embodiment IV of the present invention. 
     
    
    
     In the drawings:  1 . centrifugal impeller,  101 . axial-direction air inlet,  1011 . ring boss,  102 . upper cover board,  103 . lower cover board,  104 . impeller blade,  105 . center shaft,  1051 . center shaft hole;  2 . impeller mounting seat,  201 . bottom baffle,  202 . electric motor mounting slot,  203 . second lug,  204 . first position-limiting block,  205 . second position-limiting block;  3 . impeller cover,  301 . step,  302 . circuit board mounting frame,  303 . stopper,  304 . position-limiting slot;  4 . air chamber,  401 . air inlet,  4011 . extending edge,  402 . air-guiding wall,  403 . air-guiding channel,  404 . tangent air outlet,  405 . air deflecting board;  5 . air pump exterior shell,  501 . first air outlet,  502 . ventilating hole,  503 . assembly chamber,  504 . air pump lower shell,  5041 . first lug,  5042 . second concave port,  5043 . first fastening member,  505 . air pump upper cover,  5051 . first concave port,  5052 . position-limiting inserting tab,  506 . first air inlet,  507 . electric motor locking plate,  508 . supporting rod,  509 . position-limiting board;  6 . electric motor,  7 . lithium battery,  8 . circuit board,  81 . through hole;  9 . waterproof exterior shell,  901 . lower shell body,  9011 . second air outlet,  9012 . exterior thread,  9013 . first guiding chute,  9014 . groove,  9015 . fused edge connecting slot seat,  9016 . second guiding chute,  902 . waterproof upper cover,  9021 . interior thread,  9022 . clamping slot,  9023 . second fastening member;  10 . one-way sealing valve piece,  11 . flat sealing surface,  12 . seal ring,  13 . ventilating slot,  14 . inflatable swim ring,  141 . manual inflation and deflation valve,  15 . fused edge,  151 . clamping block,  16 . switch button,  17 . charging port. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     As follows, the present invention is further described with specific embodiments. 
     Embodiment I 
     As shown in  FIGS.  1  to  9   , the present invention provides an air-flow channel structure of an air pump. The air-flow channel structure of the air pump includes the shell body and the centrifugal impeller  1 . The shell body includes the impeller mounting seat  2  and the impeller cover  3 . The impeller mounting seat  2  and the impeller cover  3  are sealingly connected. The air chamber  4  that is configured to be provided with the centrifugal impeller is formed between the impeller mounting seat  2  and the impeller cover  3 . The centrifugal impeller  1  is arranged in the air chamber  4 . The air inlet  401  of the air chamber  4  is arranged along an axial direction of the centrifugal impeller  1  on the impeller cover  3 . The air inlet  401  communicates with the axial-direction air inlet  101  of the centrifugal impeller  1 . The impeller mounting seat  2  is provided with the bottom baffle  201 . Above the bottom baffle  201 , the air chamber  4  is connected to the air-guiding wall  402  that gradually expands in a spiral shape around the axis of the centrifugal impeller  1 . The air-guiding wall  402  is arranged perpendicular to the bottom baffle  201 . A gap is provided between the air-guiding wall  402  and the centrifugal impeller  1 , and the gap forms the air-guiding channel  403 . The air-guiding wall  402  is gradually away from the centrifugal impeller  1  from the head end of the air-guiding channel  403  to the tail end of the air-guiding channel  403 . The air chamber  4  is provided with the tangent air outlet  404  at the tail end of the air-guiding channel  403 . The tangent air outlet  404  communicates with the air-guiding channel  403  and an exterior part of the air chamber  4 . Air flows to the axial-direction air inlet  101  of the centrifugal impeller  1  from the air inlet  401 . The centrifugal impeller  1  radically blows air, and the air flows from the head end of the air-guiding channel  403  to the tail end of the air-guiding channel  403  and flows out of the air chamber  4  from the tangent air outlet  404 . 
     The air-flow channel structure of the air pump in the present invention is provided with the air-guiding wall  402  that gradually expands in a spiral shape around the axis of the centrifugal impeller  1 , which forms the increasingly wider air-guiding channel  403 . The head end of the air-guiding channel  403  is configured to block the circular flow of airflows and guides the air blown out radically from the centrifugal impeller  1  to flow along the air-guiding channel  403 . Under the guidance of the air-guiding channel  403 , most of the airflows can flow out of the air chamber  4  from the tangent air outlet  404  located at the tail end of the air-guiding channel  403 . The airflows are guided more smoothly, resulting in a faster flowing speed of the air and a higher inflating/aspirating efficiency. 
     The side, facing towards the axial-direction air inlet  101  of the centrifugal impeller  1 , of the air inlet  401  extends downwards to form the extending edge  4011 . The side, facing towards the air inlet  401 , of the axial-direction air inlet  101  of the centrifugal impeller  1  extends upwards to form the ring boss  1011 . The extending edge  4011  protrudes into the ring boss  1011 . That is, the extending edge  4011  and the ring boss  1011  have an interleaved nesting arrangement, where the formed labyrinth structure can better prevent air from leaving the air inlet  401 . 
     The impeller cover  3  is provided with the step  301  that matches the outline of the air-guiding wall  402 . The surface of the step  301  is a flared shape that concaves from the outer circumference towards the center, which assists the air-guiding channel  403  to operate, improving the performance of the air-guiding channel  403  in guiding and gathering the air flows to the centrifugal impeller  1 . 
     As shown in  FIGS.  7  to  9   , the centrifugal impeller  1  includes the upper cover board  102 , the lower cover board  103 , and a plurality of impeller blades  104  that are connected between the upper cover board  102  and the lower cover board  103 . The center of the centrifugal impeller  1  is provided with the center shaft  105 , and the center of the center shaft  105  is formed with the center shaft hole  1051  which is configured to connect an electric motor. The external diameter D 1  of the lower cover board  103  is smaller than the external diameter of the upper cover board  102 . Compared to open impellers, the centrifugal impeller in the present invention makes the airflows to flow along a preset path better, which improves the inflating/aspirating efficiency. Compared to closed impellers, the centrifugal impeller in the present invention is more convenient to process and manufacture in a less costly manner. The external diameter D 1  of the lower cover board  103  of the centrifugal impeller  1  is no more than the diameter D 2  of the axial-direction air inlet  101 , which can be integrally molded by molds without additional welding or bonding processes, thus simplifying the process and reducing costs. 
     The upper cover board  102  is obliquely arranged gradually upwards from the outer side to the inner side radically. The impeller blades  104  extend to the center shaft from an edge of an outer side of the upper cover board  102  to the inner side and extend upwards to protrude into the ring boss  1011 . Upper end surfaces of the impeller blades  104  gradually go upwards obliquely along with the upper cover board  102 , where the impeller blades  104  are located in a section from the edge of the outer side of the upper cover board  102  to the ring boss  1011 . Upper end surfaces of the impeller blades  104  gradually go downwards obliquely, where the impeller blades  104  are located in a section from the ring boss  1011  to the center shaft  105 . The widths W 2 , located in the section from the ring boss  1011  to the center shaft  105 , of the impeller blades  104  is larger or partially larger than the widths W 1 , located in a section from the edge of the outer side of the upper cover board  102  to the ring boss  1011  and hidden under the upper cover board  102 , of the impeller blades  104 , and W 1  and W 2  is also varying. Different from the closed impellers in prior art, the impeller in the present invention is further provided with the impeller blades  104  at the axial-direction air inlet  101 , where the air flows in from the axial-direction air inlet  101  and is blown out by the impeller blades  104 . Simultaneously, the lower cover board  103  gathers the air to ensure that the air does not exit from underneath. When centrifugal force is in action, the air will be exhausted out radically from the centrifugal impeller  1  under the centrifugal force even when the lower cover board  103  is not fully covering the impeller blades  104 . The oblique structure of the impeller blades  104  is also beneficial for guiding the air flows. Because different air pressures are generated by different blade widths, air enters in from the axial-direction air inlet  101  of the impeller, flows fast downwards under the guidance from the impeller blades  104  in the downwards oblique section in the inner side of the ring boss  1011 , and flows out radically from the centrifugal impeller  1 , which prevents the air from leaving the axial-direction air inlet  101  of the impeller and speeds up efficient flows of the air. 
     In this embodiment, the centrifugal impeller  1  is an integrally molded plastic impeller that coordinates with a direct current (DC) motor. It has characteristics, such as lightweight and low cost. 
     As shown in  FIGS.  1  to  6   , the present invention provides a micro air pump. The micro air pump is specifically an aspirating pump and further includes the electric motor (the electric motor is not shown). The electric motor is connected to and drives the centrifugal impeller  1  to rotate by the center shaft hole  1051 . The sidewall of the impeller mounting seat  2  is provided with the first air outlet  501  to communicate with the tangent air outlet  404 . The impeller cover  3  extends upwards to form an air inlet sidewall at the air inlet  401 . 
     The air inlet sidewall is provided with the ventilating hole  502 . The ventilating hole  502  is configured to communicate with the first air outlet  501  and the outside and to provide an air inlet channel. In an aspirating process of the air pump, when the air inside the inflatable product has been completely pumped out and the air pump is not turned off in time resulting in its continued pumping, the air inlet  401  may be blocked. At this time, a small amount of air can enter through the ventilating hole  502  to maintain the pumping circulation, thus avoiding damage to the electric motor and the circuit board due to the temperature increase. 
     Embodiment II 
     As shown in the  FIG.  10    and  FIG.  11   , this embodiment differs from the Embodiment 
     I in that the micro air pump further includes the air pump exterior shell  5 . The shell body is a part of the air pump exterior shell  5 . The air pump exterior shell  5  is provided with the assembly chamber  503  beneath the air chamber  4 . The sidewall of the assembly chamber  503  is provided with the first air outlet  501 . The tangent air outlet  404  communicates with the assembly chamber  503  to communicate with the first air outlet  501 . The air deflecting boards  405  are arranged above and beneath the tangent air outlet  404 , respectively. The air deflecting boards  405  are obliquely arranged from top to bottom along with the direction of the air flowing out. By arranging the oblique air deflecting boards  405  at the tangent air outlet  404 , performances concerning guiding and gathering the air has been improved, and the airflows are guided to flow out of the air chamber  4  from the tangent air outlet  404  more smoothly and efficiently, which further speeds up the flowing of the air and improves the aspirating efficiency. 
     The electric motor  6  is arranged inside the assembly chamber  503 . The lithium battery  7  and the circuit board  8  are further arranged inside the assembly chamber  503 . When the micro air pump is working, the air is received by the air inlet  401  and is pumped into the assembly chamber  503  from the tangent air outlet  404 . Since the first air outlet  501  of the micro air pump is arranged at the assembly chamber  503 , the air that is guided into the assembly chamber  503  can flow inside the assembly chamber  503 , and the heat of the electric motor  6 , the lithium battery  7 , the circuit board  8 , and other components is released from the first air outlet  501 , which cools and lengthens the service life of the air pump. 
     Embodiment III 
     As shown in the  FIGS.  12  to  27   , this embodiment differs from the Embodiment I in that the air-flow channel structure of the air pump of this embodiment has the air-guiding wall  402  directly formed by a sidewall of the impeller mounting seat  2 . The impeller cover  3  is fitted with the air-guiding wall  402  in shape to be fastened above the air-guiding wall  402 . 
     The micro air pump is an inflator pump, including the air-flow channel structure of the air pump, the air pump exterior shell  5 , the electric motor  6 , the circuit board  8 , and the lithium battery  7 . The electric motor  6  is a coreless motor, which is connected to and drives the centrifugal impeller  1  to rotate. The air pump exterior shell  5  includes the air pump lower shell  504  and the air pump upper cover  505 . The air pump exterior shell  5  is provided with the first air inlets  506  and the first air outlet  501 . The first air inlets  506  are air inlet meshes, which is provided on the air pump upper cover  505 . The first air outlet  501  is arranged at the bottom of the air pump lower shell  504 . The shell body is provided inside the air pump exterior shell  5 . The air pump lower shell  504 , the air pump upper cover  505 , and the impeller mounting seat  2  are removably assembled with each other in a limiting and clamping manner. The impeller mounting seat  2  and the impeller cover  3  are removably assembled with each other in the limiting and clamping manner. One end of the air inlet  401  of the air chamber  4  communicates with the first air inlets  506  of the air pump exterior shell  5 . The tangent air outlet  404  communicates with the first air outlet  501  of the air pump exterior shell  5 . The air deflecting board  405  is arranged above the tangent air outlet  404 . The air deflecting board  405  is obliquely arranged from top to bottom along with the direction of the air flowing out. Air enters in from the first air inlets  506  and flows to the axial-direction air inlet  101  of the centrifugal impeller  1  from the air inlet  401  on the impeller cover  3 . The centrifugal impeller  1  radically blows air, and the air flows from the head end of the air-guiding channel  403  to the tail end of the air-guiding channel  403 , flows out of the air chamber  4  from the tangent air outlet  404  and is exhausted from the first air outlet  501 . 
     The impeller mounting seat  2  is provided with the ventilating hole  502  on the outside of the air-guiding wall  402 . The ventilating hole  502  is configured to communicate with the first air outlet  501  and the outside and to provide an air inlet channel. In an inflating process of the air pump, when the inflatable product reaches an air-saturated state and the air pump is not turned off in time resulting in its continued inflating, it may cause the inflatable product to burst due to over-saturation. By arranging the ventilating hole  502 , the present invention enables that excessive air is released from the ventilating hole  502  under air pressure, thus avoiding damage to the inflatable product caused by not turning off the air pump in time. 
     The circuit board  8  is electrically connected to the electric motor  6 . The upper end of the impeller cover  3  is formed with the circuit board mounting frame  302 , including three supporting blocks that extend upwards. The circuit board  8  is limited and clamped in the circuit board mounting frame  302  by the three through holes  81  arranged on the circuit boards  8 , where the three through holes  81  match the three supporting blocks. A gap for air to flow in is kept between the circuit board  8  and the air inlet  401  on the impeller cover  3 . Corresponding to the circuit board  8 , the air pump upper cover  505  is provided with the switch button  16  and the charging port  17 . 
     The impeller mounting seat  2  is further formed with the electric motor mounting slot  202  and the lithium battery position-limiting structure at the bottom of the impeller mounting seat  2 . The upper part of the electric motor  6  is embedded inside the electric motor mounting slot  202 , and the electric motor locking plate  507  is further connected to the lower part of the electric motor  6 . The electric motor locking plate  507  is supported and arranged on the supporting rods  508  that are connected to the air pump lower shell  504  by a bottom positioning slot, and the electric motor locking plate  507  is configured to lock the electric motor  6  in longitudinal direction. The lithium battery position-limiting structure is the two position-limiting boards  509  that are connected beneath the impeller mounting seat  2  to limit the position of the lithium battery  7  in horizontal direction, and the lithium battery  7  is position-limited and arranged between the two position-limiting boards  509 . The lithium battery  7  is vertically supported and arranged between the air pump lower shell  504  and the impeller mounting seat  2 . 
     The air pump lower shell  504  and the air pump upper cover  505  are position-limited and clamped with each other by an embedded structure between the first lug  5041  and the first concave port  5051 . The air pump lower shell  504  and the impeller mounting seat  2  are position-limited and clamped with each other by an embedded structure between the second concave port  5042  and the second lug  203 . The top of the impeller mounting seat  2  is formed with the first position-limiting block  204  and the second position-limiting block  205 . The stopper  303  is formed on the impeller cover  3 . The position-limiting slot  304  is formed at one side of the stopper  303 , and the position-limiting slot  304  can be fitted and clamped with the first position-limiting block  204 . The impeller cover  3  is matched with the first position-limiting block  204  and is position-limited and clamped with the impeller mounting seat  2  by the position-limiting slot  304 . The position-limiting inserting tab  5052  is formed inside the air pump upper cover  505 . The position-limiting inserting tab  5052  can fit to be embedded between the second position-limiting block  205  and the other side of the stopper  303  and is position-limited and clamped with the impeller mounting seat  2 . The air pump lower shell  504 , the air pump upper cover  505 , the impeller mounting seat  2 , and the impeller cover  3  are removably assembled. 
     The waterproof air pump includes the waterproof exterior shell  9  and the micro air pump removably connected to the waterproof exterior shell  9  inside. The waterproof exterior shell  9  includes the lower shell body  901  and the waterproof upper cover  902 . The lower shell body  901  is removably connected and relatively sealed to the waterproof upper cover  902  through a thread. The micro air pump is fastened to and removably connected to the lower shell body  901  by a screw fastening assembly. The bottom of the lower shell body  901  is formed with the second air outlet  9011 . The second air outlet  9011  communicates with the first air outlet  501  of the micro air pump, and the second air outlet  9011  is connected to the one-way sealing valve piece  10 , which can sufficiently avoid air leakage. 
     The interior wall of the waterproof upper cover  902  is provided with the interior thread  9021 , and the exterior wall of the lower shell body  901  is provided with the exterior thread  9012  that matches the interior thread  9021 . Each of the waterproof upper cover  902  and the lower shell body  901  is provided with the flat sealing surface  11 . The flat sealing surface  11  of the waterproof upper cover  902  abuts against the flat sealing surface  11  of the lower shell body  901 , and the seal ring  12  is arranged between the two flat sealing surfaces  11  to realize a seal between the waterproof upper cover  902  and the lower shell body  901 . The threads are two threads largely spaced, which reduces the time and force required to screw tightly and avoids unintended loosening. When an air-saturation state is reached, the waterproof upper cover  902  can be screwed fast to realize a sealing effect. 
     The micro air pump is fastened with the lower shell body  901  by a screw fastening assembly. The screw fastening assembly includes the first guiding chute  9013  correspondingly arranged on the lower shell body  901  and the micro air pump, respectively, and the convexly arranged first fastening members  5043  that are matched with and rotatably fastened inside the first guiding chute  9013 . The first guiding chute  9013  is arranged in the lower end of the lower shell body  901  and is arranged along the circumference of the lower shell body  901 . The first fastening members  5043  are arranged at the lower end of the micro air pump. The first air outlet  501  of the micro air pump is cylindrical and arranged convexly downward the lower end. The upper end of the second air outlet  9011  of the lower shell body  901  is formed with the groove  9014  that matches the first air outlet  501  of the micro air pump in shape. The first air outlet  501  is embedded inside the groove  9014  and abuts against and communicates with the second air outlet  9011 . The end surface of the bottom of the lower shell body  901  is formed with four ventilating slots  13  equally spaced. The ventilating slot  13  is radically arranged to traverse the end surface of the bottom of the lower shell body  901 . One end of the ventilating slot  13  communicates with the second air outlet  9011 , and the other end of the ventilating slot  13  communicates with the exterior part of the lower shell body  901 . 
     An inflatable product includes the inflatable product body and the waterproof air pump. The inflatable product body is the inflatable swim ring  14 , as shown in the  FIG.  27   . The exterior wall of the lower shell body  901  is sealingly connected to the inflatable swim ring  14  by the fused edge  15 . The second air outlet  9011  is located at the interior cavity of the inflatable swim ring  14 . The waterproof upper cover  902  is exposed on the exterior part of the inflatable swim ring  14 . The inflatable swim ring  14  is further provided with the manual inflation and deflation valve  141 . 
     The exterior wall of the lower shell body  901  is provided with the fused edge connecting slot seat  9015 , and the fused edge  15  that is embedded and assembled with the fused edge connecting slot seat  9015 . The fused edge  15  is configured to connect and seal the lower shell body  901  with the inflatable product. The upper end surface of the fused edge  15  is provided with several clamping blocks  151  along the circumference of the fused edge  15 . The lower end surface of the waterproof upper cover  902  is provided with several clamping slots  9022  along the circumference of the waterproof upper cover  902 . The clamping blocks  151  are clamped in the clamping slots  9022  to avoid loosening of the threads. 
     As shown in the  FIGS.  12  to  27   , the method for using the inflatable product in this embodiment is as follows: When the inflatable product needs to be inflated, the waterproof upper cover  902  is screwed off from the lower shell body  901 . Meanwhile, the micro air pump is screwed and fastened to the lower shell body  901 , and the micro air pump can be controlled to start by the switch button  16  to inflate the inflatable product. After the inflation is completed, the waterproof upper cover  902  is connected to the lower shell body  901  through a thread. When the waterproof air pump does not work, the inflatable product can be inflated through the manual inflation and deflation valve  141 , which provides an emergency backup inflation method for the inflatable product. Additionally, the inflatable product can further be deflated fast through the manual inflation and deflation valve  141  to facilitate storing of the inflatable product. In addition, when the single micro air pump is configured with a plurality of inflatable products, the micro air pump is simply removed from the lower shell body  901  of the current inflatable product and is screwed and fastened to the lower shell body  901  of the inflatable product to be inflated. After the micro air pump is removed from the lower shell body  901 , the first air outlet  501  of the micro air pump is connected to the air inlets of the other inflatable products through the air nozzle to inflate the other inflatable products. 
     Embodiment IV 
     As shown in  FIG.  28    and  FIG.  29   , this embodiment differs from the Embodiment III in that the lower shell body  901  of the waterproof air pump and the waterproof upper cover  902  are fastened with each other by a screw fastening assembly, and the micro air pump and the lower shell body  901  are also fastened with each other by a screw fastening assembly. The lower shell body  901  and the waterproof upper cover  902  are relatively sealed by a seal ring arranged beneath the waterproof upper cover  902 . The screw fastening assembly, which is configured to connect the lower shell body  901  and the waterproof upper cover  902 , includes the second guiding chute  9016  arranged on the lower shell body  901  and the second fastening member  9023  convexly arranged on the waterproof upper cover  902 . 
     The above descriptions are only four specific embodiments of the present invention, but the designs and ideas of the present invention are not limited herein. Any non-substantial modification of the present invention based on the ideas shall fall in the scope of protection of the present invention.