Control apparatus and control method for hybrid vehicle

A control apparatus for a hybrid vehicle including:

• an engine in which a low torque operation mode, in which the engine is operated at a low output torque, and a high torque operation mode, in which the engine is operated at a higher output torque than in the low torque operation mode, are executed;
• a motor generator;
• an output portion for transmitting torque to a drive wheel;
• a differential mechanism that distributes the torque of the engine to the motor generator and the output portion;
• and
• a locking apparatus that is switched between an engaged condition, in which the motor generator is prevented from rotating, and a disengaged condition, in which the motor generator is allowed to rotate,
• the control apparatus comprising:
• a controller configured to reduce a rotation speed of the motor generator before the locking apparatus is switched from the disengaged condition to the engaged condition,
• the controller being configured to start switching the locking apparatus to the engaged condition when the rotation speed decreases to a predetermined operation permission rotation speed,
• the controller being configured to control the locking apparatus such that from the start of the switch to the engaged condition onward, the rotation speed decreases from the operation permission rotation speed to an engagement rotation speed at which the motor generator is in the engaged condition,
• the controller being configured to control the locking apparatus such that a decrease rate of the rotation speed when switching from the disengaged condition to the engaged condition in the low torque operation mode is higher than a decrease rate of the rotation speed when switching from the disengaged condition to the engaged condition in the high torque operation mode,
• the decrease rates being obtained by dividing the operation permission rotation speed by a time required for the rotation speed to decrease from the operation permission rotation speed to the engagement rotation speed.