1. Field of the Invention
The present invention relates to an internal combustion engine and more particularly to means for suppressing output torque fluctuations in an internal combustion engine.
2. Description of the Prior Art
In internal combustion engines, particularly those of the reciprocating piston type, there are produced cyclical fluctuations in the output torque. Since such output torque fluctuations cause noise and vibrations, it is desirable to suppress them as much as possible. In Japanese patent application No. 53-74100 filed on June 21, 1978 and disclosed for public inspection on Jan. 8, 1980 under the disclosure No. 55-1431, there is disclosed an arrangement which electromagnetically suppress the torque fluctuations. According to the proposal by the Japanese patent application, the means for suppressing the engine output torque fluctuations includes first magnetic flux generating means having permanent magnets mounted on the engine output shaft to rotate therewith, and second magnetic flux generating means having electromagnets mounted on a stationary part of the engine so as to oppose the permanent magnets. The electric current is applied to the electromagnets to energize them so that the engine output shaft is applied with an electromagnetic torque which is of an opposite phase with respect to the torque which is produced as the result of combustion. In this type of arrangement, the electromagnetic torque changes cyclically as the permanent magnet on the output shaft rotates so that electric power is consumed irrespective of whether a positive or negative torque is applied electromagnetically to the output shaft with respect to the direction of rotation of the output shaft. It will therefore be understood that the arrangement proposed by the Japanese patent applications is disadvantageous from the viewpoint of fuel economy.
It should further be pointed out that the prior art described above is designed so that the value of the electromagnetic torque can be changed through control of the electric current applied to the electromagnets, however, it is impossible in this arrangement to control the values of the positive and negative torques independently. Further, the prior art does not suggest anything as to how the torque fluctuation suppressing means shall be controlled to meet requirements under various engine operating conditions such as acceleration, deceleration and high power operation.