Tension adjusting device for self-adaptive engine front end accessory gear train

The invention discloses a tension adjusting device for a self-adaptive engine front end accessory gear train. The tension adjusting device comprises the engine front end accessory gear train and a belt tension control system. The belt tension control system comprises a piezoelectric sensor, an angle encoder, a comparator, a controller and an actuator. When the rotation speed of a crankshaft of an engine is zero, a tensioning wheel is in the preset position where the belt tension is smaller all the time; when the engine is started, the rotation speed of the crankshaft is gradually increased from zero, and the controller immediately controls the actuator to act, so that the tensioning wheel moves to the preset position where the belt tension is larger; and after the rotation speed of the crankshaft is stable, a tension value obtained by the piezoelectric sensor is compared with a preset tension value through the comparator, then the controller controls the actuator to act to adjust the position of the tensioning wheel so that the tension can be kept in a constant state. According to the tension adjusting device, the rotation speed of the crankshaft of the engine and the dynamic tension applied to the ribbed belt can be measured in real time, and the position of the tensioning wheel can be adjusted actively, so that the purpose that the tension of the belt is adjusted according to the running state of the self-adaptive engine is achieved.