Control device for hybrid vehicle

A control device for a hybrid vehicle, applied to a hybrid vehicle comprising:

• an engine;
• a motor-generator;
• an output portion that outputs torque to a drive wheel;
• a differential mechanism having a plurality of rotating elements that are differentially rotatable with respect to one another, the engine being joined to one of the plurality of rotating elements, the motor-generator being joined to another one of the plurality of rotating elements, and the output portion being joined to yet another one of the plurality of rotating elements;
• and
• a selectable one-way clutch comprising a rotating member that can receive a reaction torque of the engine and that is provided to the differential mechanism, and that can be changed over between a locked mode in which, in the state of receiving the reaction torque, it prohibits positive rotation of the rotating member while permitting negative rotation of the rotating member in the direction opposite to the positive rotation, and a free mode in which, in the state of receiving the reaction torque, it permits both the positive rotation and the negative rotation of the rotating member;
• wherein, if a traveling state of the hybrid vehicle is a specified traveling state in which greater change than a reference value of a torque upon the output portion due to input to the drive wheel from a road surface over which the vehicle is traveling has occurred a plural number of times within a predetermined time interval, then, when the selectable one-way clutch is in the locked mode, it is changed over to the free mode, and, when the selectable one-way clutch is in the free mode, it is kept in the free mode.