Please select the most similar patent number from A, B, C and D. Which number is?
A power-assisted bicycle with a mid-mounted motor, comprising a frame and a mid-mounted motor driving system mounted on the frame. The mid-mounted motor driving system comprises a motor (2), a controller (3), a battery (4), and a transmission system (5); the transmission system (5) is provided on the lower end of an inclined pipe (1); at least the motor (2) in the motor (2), the controller (3), and the battery (4) is provided in the inclined tube (1) of the frame; a driving unit of the motor (2) is in driving connection with the transmission system (5); the controller (3) is in signal connection with the motor (2); and the battery (4) is electrically connected to the motor (2) and the controller (3) to supply working power.
A: Disclosed is an electric vehicle, comprising a chassis (1), a vehicle body and a power battery (71), wherein the chassis (1) comprises a frame system (2), a steering motor damping system (13) mounted on the frame system (2), a wheel system (12) connected to the steering motor damping system (13), a steering system (3) mounted on the frame system (2), and a braking system (4) mounted on the frame system (2); and the wheel system (12) comprises a left front wheel (121) using a hub motor, a left rear wheel (123) using a hub motor, a right front wheel (122) using a hub motor, and a right rear wheel (124) using a hub motor. Driving the wheels (121, 122, 123, 124) with the hub motors can omit a traditional mechanical transmission system, so as to simplify the structure of the chassis (1) and reduce the weight of the chassis (1). Compared with a traditional electric vehicle, the electrical vehicle has a lighter weight, smaller volume, reduced mechanical transmission loss, and improved electrical energy utilization rate.
B: A hybrid drive system comprises a power battery device (1), a range extender system (2), and a motor driving system (3); the power battery device (1) is configured to supply power for the motor driving system (3); the range extender system (2) comprises an engine (201) and a generator (202); the generator (202) can be driven by the engine (201) to generate power so as to supply power for the motor driving system (3) and/or charge the power battery device (1); the hybrid drive system further comprises a vehicle control unit configured to control the engine (201) and/or the generator (202) of the range extender system (2) to generate driving force; the range extender system (2) is mechanically connected to a main coupling mechanism (4), so that the generated driving force is transmitted to a main driving axle (5) of the vehicle by means of the main coupling mechanism (4) to drive wheels on both sides of the axle (5) to rotate. Also provided is a vehicle having the hybrid drive system. According to the hybrid drive system and the vehicle having same, the vehicle control unit is utilized to control the engine (201) and/or the generator (202) of the range extender system (2) to generate driving force for different application conditions, and thus the economy of the vehicle can be effectively improved.
C: Disclosed is a multi-functional children&#39;s scooter provided with a power device. The scooter comprises a frame (1), wheels (2), a handlebar (3) and a saddle (4). A controller (5), an electric motor (6) and a battery (7) are mounted in the middle of the frame (1). The battery (7) is mounted inside a tube body of the frame (1) and is connected to the controller (5). The handlebar (3) is provided with a brake handle and a power switch (8). The power switch (8) is connected to the controller (5). The wheels (2) comprise a front wheel and a rear wheel. One side of the rear wheel is provided with a driven gear, and a brake is mounted on the other side of the rear wheel. The brake is connected to the brake handle by means of a brake cable. A brake sensor (9) connected to the controller (5) is mounted in the brake. The electric motor (6) is connected to the controller (5). An electric motor shaft of the electric motor (6) is connected to a drive gear, and the drive gear is connected to the driven gear by means of a transmission chain. The scooter is additionally provided with a power device, can be used, instead of walking on a short trip, by children when playing independently, and can also be used instead of walking on a longer trip, e.g. going out with parents for a ride, and frees the feet of the children when the children ride the scooter, thereby increasing the fun for the children enjoying the scooter.
D: A central drive device and a bicycle having said device. The central drive device comprises a housing, a motor (1) provided in the housing, a speed reduction mechanism, a central shaft (11) and a crankset device, the speed reduction mechanism being in transmission connection with the motor (1), the central shaft (11) being used for being connected to a pedal device and being rotatably provided in the housing, and said device further comprises a first clutch (5); the first clutch (5) has one end connected to an output end of the speed reduction mechanism, and the other end connected to the crankset device; the first clutch (5) comprises a transmission state and a release state; the crankset device is connected to the central shaft (11) by means of a second clutch (7), such that the central shaft (11) drives the crankset device to rotate; in a power-assist operating mode, the first clutch (5) enables transmission connection between the output end of the speed reduction mechanism and the crankset device, such that the output end transmits power to the crankset device; and in a non-power-assist operating mode, the first clutch (5) disconnects the power connection between the output end of the speed reduction mechanism and the crankset device. Such a central drive device can enable a person to pedal a bicycle in a lighter and less laborious manner.
Answer: D