Device for estimating degree of fatigue of motive force transmitting component, and method for estimating degree of fatigue of motive force transmitting component

A fatigue degree estimation device for a power transmission component in a power transmission system from a driving source comprising a motor/generator and an internal combustion engine to a wheel of a hybrid electric vehicle, the device comprising:

• a memory storing a fatigue threshold database and a characteristics database of the motor/generator;
• and
• a processor coupled to the memory, wherein the processor is configured to perform the processing to:
• receive, from the motor/generator, information of an operating state of the vehicle at least once per a predetermined period of time, the information including the input current and voltage to the motor/generator, the frequency of the motor/generator, and the rotational speed of the motor/generator;
• obtain, based on the information of the operating state of the vehicle and the characteristics database of the motor/generator, a magnitude and a direction of a first torque outputted by the motor/generator;
• calculate, based on the first torque and a second torque outputted by the internal combustion engine, output torque outputted from the driving source by adding the first torque and the second torque;
• estimate, based on the calculated output torque, a magnitude and a direction of an acting torque acting on the power transmission component;
• estimate a cumulative fatigue damage degree for the power transmission component by different estimation methods depending on the type of power transmission component, based on the magnitude and the direction of the acting torque, and the number of times that the acting torque has acted on the power transmission component within the predetermined period of time, wherein estimating the cumulative fatigue damage degree comprises:
• when the power transmission component is a gear, by accumulating the magnitude of the acting torque for each direction of the acting torque acting on the gear within the predetermined period, or
• when the power transmission component is a shaft, by accumulating the magnitude of the acting torque regardless of the direction of the torque acted on the shaft within the predetermined period;
• and
• compare the estimated cumulative fatigue damage degree with a corresponding threshold stored in the fatigue threshold database;
• and
• output a signal indicating that the cumulative fatigue damage degree exceeds a predetermined threshold for the power transmission component, when the estimated cumulative fatigue damage degree exceeds the corresponding threshold for the power transmission component.