Please select the most similar patent number from A, B, C and D. Which number is?
A blower (100), comprising: a motor (110); a fan (120), being driven by the motor (110) to rotate about a central axis (101); a battery pack (130), for supplying power to the motor (110); an air duct assembly (140), forming an air inlet (141) for air intake and an air outlet (142) for air outlet; and further comprising: a first handle (150), forming a first holding portion (151) for holding; and a second handle (160), forming a second holding portion (161) for holding. At least part of projection of the battery pack (130), in the radial direction of the central axis (101), on a plane (102) passing through the central axis (101) is located between the first handle (150) and the second handle (160). The blower (100) facilitates reducing the burden when a user uses the blower (100).
A: A food processor, comprising a main machine (100) and a blending cup assembly (200). The blending cup assembly (200) comprises a cup body (210), a blade assembly (220), and a magnetic conductive disc (230). A coil disc (110), a blending motor (120), and a circuit board (130) are provided in the main machine (100). The main machine (100) comprises a housing body (140) that comprises a housing (141) and a support (142). A first air duct (151) and a first fan (161) located in the first air duct (151) are provided in the housing (141), a first air inlet (171) and a first air outlet (181) communicated with the first air duct (151) are formed on the surface of the housing (141), and the blending motor (120) is located in the first air duct (151). A second air duct (152) and a second fan (162) located in the second air duct (152) are provided in the housing (141), a second air inlet (172) and a second air outlet (182) communicated with the second air duct (152) are formed on the surface of the housing (141), and the circuit board (130) is located in the second air duct (152). A third air duct (153) and a third fan (163) are provided in the support (142), a third air inlet (173) and a third air outlet (183) communicated with the third air duct (153) are formed on the surface of the support (142), and the coil disc (110) is located in the third air duct (153). The first air duct (151), the second air duct (152), and the third air duct (153) are isolated from each other. The food processor improves the heat dissipation efficiency.
B: A micro water pump, comprising: a housing (100) having an accommodating chamber (101), an impeller assembly (200) rotatably fixed in the accommodating chamber (101), a winding assembly (300) used for driving the impeller assembly (200) to rotate, and a flexible circuit board (400) electrically connected to the winding assembly (300). The housing (100) comprises a base (110) and an upper cover (120) covering the base (110); the side of the base (110) facing the upper cover (120) is recessed to form a recess (111); the bottom wall of the recess (111) protrudes toward the upper cover (120) to form an enclosing table (130); the base (110), the enclosing table (130), and the upper cover (120) together enclose the accommodating chamber (101); the enclosing table (130) comprises a top wall (131) and an enclosing wall (132) which is arranged spaced apart from the side wall of the recess (111); a stepped shaft (140) arranged spaced apart from the enclosing wall (132) is protrudingly provided on the top wall (131) in the direction away from the upper cover (120); the enclosing wall (132), the top wall (131), and the stepped shaft (140) together enclose a mounting chamber (133) which is used for fixing the winding assembly (300) and sealingly isolated from the accommodating chamber (101); the stepped shaft (140) comprises a first shaft portion (141) fixed on the top wall (131) and a second shaft portion (142) fixed on the first shaft portion (141); and the outer diameter of the first shaft portion (141) is larger than that of the second shaft portion (142), and the central axis of the first shaft portion (141) is the same as that of the second shaft portion (142).
C: An air blower comprising: a housing (200), where an air inlet (203) is provided on the housing (200) and air is introduced via the air inlet (203); a motor (300) arranged within the housing (200); an axial flow fan driven by the motor (300) to rotate around a fan axis and to produce an airflow; an air blowing pipe (422) connected to the housing (200) and provided with an air outlet (601), where the airflow is blown out from the air outlet (601); and a duct (400) used for guiding the airflow to move towards the air outlet (601). An airflow channel (602) is provided within the housing (200) and the air blowing pipe (422). The airflow channel (602) comprises an upstream area(201) between the air inlet (203) and the axial flow fan and a downstream area (202) between the axial flow fan and the air outlet. The motor (300) is provided in the upstream area (201). The duct (400) is provided in the downstream area (202).
D: Disclosed is a power tool (100), comprising: a casing (11), a motor (12), an output shaft (131), a working head (13), a transmission assembly, an auxiliary handle (20), and a damping assembly (25), wherein the casing is provided with a main handle (111) for a user to grip; the motor is arranged in the housing, and the motor is further provided with a driving shaft (121); the working head is provided with the output shaft (131) and an abrasive disc (132) connected to the output shaft, and the output shaft is driven by the motor; the front end of the auxiliary handle is mounted on the casing and near the working head, and the auxiliary handle comprises a grip portion (21) extending along a center line (103) thereof; the damping assembly comprises a mass member (251) and an elastic element (252), wherein the auxiliary handle further comprises an end cap (23) arranged at the rear end of the grip portion (212), with the rear end being further away from the casing with respect to the front end; an accommodating chamber (24) for accommodating the damping assembly is enclosed by the end cap and the grip portion when same are integrated; the elastic element (252) is arranged between the mass member (251) and the chamber wall of the accommodating chamber; and the ratio of the inherent frequency W1 of the damping assembly to the rotational frequency W2 of the output shaft during rotating is greater than or equal to 0.7 and less than or equal to 1.3. The power tool has a good damping effect.
Answer: C