Please select the most similar patent number from A, B, C and D. Which number is?
A piston type industrial pump comprises a power device (1), a pumping device (2) and a stirring device (3). A connecting pipeline is arranged between the power device (1) and the pumping device (2); the pumping device (2) is fixedly connected with the stirring device (3); the power device (1) consists of at least two power units connected in parallel; the power units comprises hydraulic oil tanks (101), motor oil pump sets (102), and a power unit base (103); and a communicating oil pipe (104) is arranged between the hydraulic oil tanks (101) of the power units. There are at least two groups of motor oil pump sets (102) provided in each power unit. Two or more power units are connected in parallel for providing superimposed power, so that the flow of a hydraulic system can meet a large-volume conveying requirement; in the meantime, all the power units are independent of each other and can work together in parallel or work independently; when one of the power units is fails, only the faulty unit is stopped for maintenance, and the other power units continuously provide power output and are spare to each other.
A: An unmanned aerial vehicle (100), comprising a vehicle body assembly (1), vehicle arm devices (2) and power devices (3). There are two vehicle arm devices (2) respectively located at two opposite sides of the vehicle body assembly (1), the two length ends of each vehicle arm device (2) are respectively an inner end (21) and an outer end (22), the inner end (21) of the vehicle arm device (2) is mounted on the vehicle body assembly (1), the vehicle arm device (2) is arranged obliquely upwards from the inner end (21) to the outer end (22), an included angle between each vehicle arm device (2) and a horizontal plane is 9-35 degrees, and one power device (3) is respectively mounted at the outer end (22) of each vehicle arm device (2). Each of the power devices (3) comprises a power unit (31), the power unit (31) comprising a power motor (311) and a propeller (312).
B: An unmanned aerial vehicle (100), comprising: a fuselage assembly (1), the fuselage assembly comprising a storage device (11); vehicle arm devices (2), the number of the vehicle arm devices being two, the vehicle arm devices being located on two sides of the fuselage assembly respectively, two ends of the length of each vehicle arm device being an inner end and an outer end respectively, and the inner ends of the vehicle arm devices being installed on the fuselage assembly; and power devices (3), one power device being mounted on the outer end of each vehicle arm device, each power device comprising a power unit (31), and each power unit comprising a power motor (311) and a propeller (312) installed on the power motor. A lifting force generated by the two power devices is coplanar to form a preset plane (S3), and the preset plane passes through the storage device.
C: A leaf spring vibration hydraulic power generation system, comprising a generator (2), a power unit (4) which provides power, and a transmission unit, which transmits power and converts same into torque, wherein the generator (2) comprises a rotor and a storage battery, which forms an excitation magnetic field; the power unit (4) and the transmission unit make the rotor of the generator (2) rotate; the rotor cuts the excitation magnetic field formed by the storage battery; and after the rotation speed of the rotor gradually increases until the voltage of the generator is higher than that of the storage battery, the generator (2) reversely charges the storage battery, and provides electric energy for other electronic apparatuses. By using an oil fluid in an oil tank and the vibration of a vehicle, a hydraulic motor (35) is driven by means of the power unit (4) and the transmission unit, thereby providing power for the generator (2), and supplying power to electronic devices of the entire vehicle and the storage battery, such that the problem of existing generators consuming the energy of an engine can be better alleviated, and the problem of the short driving range of an electric vehicle is alleviated.
D: Disclosed is a pumping system for a piston-type mortar pump. The pumping system comprises a delivery cylinder (3) with a delivery piston (31) and a piston rod arranged therein, wherein the piston rod is connected to a power apparatus of the pumping system, and a rodless chamber (33) of the delivery cylinder (3) is in communication with a material inlet (102) via a unidirectional intake valve (41). The pumping system also comprises a compensation cylinder (5) with a compensation piston (51) arranged therein, wherein the compensation piston (51) separates the compensation cylinder (5) into an out-feed chamber (52) and a buffer chamber (53), the out-feed chamber (52) is in communication with the material outlet (101), the rodless chamber (33) of the delivery cylinder (3) is in communication with the out-feed chamber (52) via a unidirectional out-feed valve (42), and the buffer chamber (53) is in communication with a rod chamber (32) of the delivery cylinder (3) to form a sealed chamber. In this way, when the delivery cylinder (3) is in a material intake stroke, matter stored in the compensation cylinder (5) is discharged via the material outlet (101), thus while taking in material, the pumping system can discharge material, thereby improving the pumping continuity of the pumping system and ensuring continuous operation of the piston-type mortar pump.
Answer: D