| 摘要 |
PURPOSE:To make propulsion efficiency optimum in response to the operational condition of a screw propeller by providing an upper rotor and a lower rotor having vertical rotary axes respectively and rotary driving mechanisms of both rotors above and below the center axis of a propeller shaft on the front edge section of a rudder support member. CONSTITUTION:The rotation speed of the propeller shaft 12 of a screw propeller 2 rotating in the arrow 23 direction as seen from the rear of a hull is detected by a rotation detector 13, this detection signal is fed to a rotation speed control unit 14, from which control signals are fed to upper and lower rotor driving motors 10a, 10b. Both driving motors rotate the upper rotor 9a in the arrow 24 direction and the lower rotor 9b in the arrow 25 direction respectively. Individual rotors are adjusted by individual motors respectively so that the thrust Ta and Tb is invariably made maximum. That is, the upper rotor 9a and lower rotor 9b are rotatively driven at the adequate rotation speed in response to the rotation speed of the screw propeller 2 and convert the rotation component of the propeller 2 into the thrust Ta, Tb most efficiently.
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