Currently, the reciprocating piston engines are relatively widely-used, and the rotor engines are also used. In order to enhance the efficiency of the engine, the dual-rotor engine has been developed. The dual-rotor engine has a variety of types, in which the scissor type dual-rotor engine is one of the relatively common types and comprises a carrier, a cylinder assembly installed on the carrier, a first and second rotor installed within the cylinder, a controller, and a transmission output mechanism for outputting power and so on. In such dual-rotor engine, each rotor is provided with a pair of sector pistons symmetrically, and the two rotors are installed on the same output shaft in such a way that two pairs of sector pistons are arranged crosswise to each other. Thus, the chamber inside the cylinder is divided into four operating chambers by means of the four sector pistons. Under the control of a rotor control mechanism, once the sector pistons rotate one cycle, each of the operating chambers does work four times in total, by which the efficiency can be enhanced substantially. Therefore, the rotor control mechanism plays a key role in the dual-rotor engine. Specifically, it is necessary for the rotor control mechanism to control the two pairs of sector pistons such that the rotation of the rotors can be stopped or started at precise positions in accordance with desired precise time sequences so as to prevent the rotors from counter-rotating. At the same time, the rotor control mechanism also needs to ensure the rotors being a precise operation state when the engine is started.
The structure of the controller in the conventional dual-rotors engine has a variety of types such as the step type, the differential type, the cam roller type and the ratchet spring capturing mechanism. None of the rotor control mechanisms such as the step type, the differential type and the cam roller type thereof enable the output shaft to rotate in a constant speed so that such mechanisms can not be used in practical applications. Moreover, the engine provided with a rotor reverse blocking device such as the ratchet spring capturing mechanism has a reliability approximate to zero. Therefore, none of the various kinds of conventional dual-rotor engines with different designs can be used in practical applications due to the fact that the controller can not precisely control the operating state when the rotors rotate.