Please select the most similar patent number from A, B, C and D. Which number is?
A mute powerful bladeless fan, comprising an air guiding member (2). The air guiding member (2) is formed by connecting an air gathering cover (22) and an air outlet cover (21) in a covering mode; through holes (23) which are coaxial are formed in the bottom surfaces of the air gathering cover (22) and the air outlet cover (21), respectively; the edge of the through hole (23) in the bottom surface of the air gathering cover (22) arches inwards in an axial direction so that the connection surface between the edge of the bottom surface of the air gathering cover (22) and the edge of the through hole (23) can form an annular fall slope (221) in smooth transition; the edge of the through hole (23) in the bottom surface of the air outlet cover (21) extends inwards in the axial direction to form a flange (212); an air blocking edge (213) is provided on the periphery of the flange (212) in a circle; air outlets (211) are evenly formed between the flange (212) and the air blocking edge (213); the edge of the through hole (23) of the air gathering cover (22) is in sealed butt joint with the flange (212); the axes of the through holes (23) are deflected to the upper portion of the air guiding member (2), so that an annular air channel (24) having a section gradually reduced from bottom to top is formed in the air guiding member (2); and an air inlet (25) communicated with the air channel (24) is formed in the lower end of the air guiding member (2).
A: A two-channel air-cooled small gasoline generator, comprising a case (1), an engine assembly (2), a silencer (3) and a magneto assembly (4) with a fan, wherein the engine assembly (2), the silencer (3) and the magneto assembly (4) are arranged in the case. The gasoline generator further comprises: a first air guiding hood (21), arranged on the engine assembly (2) in a coating mode; an air duct (32), one end of the air duct being connected to the first air guiding hood (21), and the other opposite end of the air duct being communicated with the outside; a second air guiding hood (31), arranged on the silencer (3) in a coating mode and provided with an air outlet (311) communicated with the outside; and a third air guiding hood (41), arranged on the magneto assembly (4) in a coating mode and further communicated with the second air guiding hood (31). In the generator, the engine is cooled at high efficiency, thermal power attenuation of the engine is effectively reduced, and the output of the magneto is efficient; accordingly, high-efficiency operation of the generator is guaranteed, and a good noise isolation effect is achieved with the sealed air duct.
B: An air outlet assembly, comprising: a panel (10), an air outlet (11) being arranged on the panel (10); and an air guide part (20), mounted on an air inlet side on the panel (10), an air guide channel being formed in the air guide part (20), and the air guide part (20) having an air guide inlet (21) and an air guide outlet (24), which are connected to the air guide channel, formed thereon, the air guide outlet (24) also being connected to the air outlet (11). By means of said air outlet assembly, dew is prevented from forming on a side of the panel close to the interior of a room or a vehicle. The present invention also relates to an air conditioner and a vehicle.
C: An air concentration cover (1) and a PM2.5 tester having same. The above-mentioned air concentration cover (1) comprises an air exit portion (11), an air guiding portion (12) and a mounting portion (13) used for being mounted with and connected to a fan (2), wherein the air exit portion (11), the air guiding portion (12) and the mounting portion (13) are integrally formed, and form a cavity (14) in combination for air to pass through, an air outlet (111) is provided on the air exit portion (11), and an air guiding piece (15) for guiding air is provided in the cavity (14). The above-mentioned PM2.5 tester comprises the above-mentioned air concentration cover (1).
D: A bladeless fan, comprising: a body portion (10), the body portion (10) comprising an air inlet, an air outlet, and a fan motor assembly (5) used for generating an air flow; and a nozzle (7) connected to the air outlet and used for receiving an air flow from the body portion (10) and emitting the air flow. The fan motor assembly (5) comprises: an air outlet base, first positioning seats (501) and first screw lugs (508) being provided around the periphery of the air outlet base; a motor support (54), a motor (56) being provided between the motor support and a first side of the air outlet base, and second positioning seats (541) being provided around the periphery of the motor support (54); and an air guide cover (52), a rotary impeller (53) being provided between the air guide cover and a second side of the air outlet base, and third positioning seats (521) and second screw lugs (522) being provided around the periphery of the air guide cover (52). The air outlet base is in screw connection with the air guide cover (52). Each second positioning seat (541) of the motor support (54) is clamped and limited between the first positioning seat (501) and the third positioning seat (521) after being connected to the first positioning seat (501) and the third positioning seat (521) by means of a flexible connector. The bladeless fan can change the movement direction of the air flow in the fan, reduce the overall height of the fan, and reduce the overall volume.
Answer: D