Vehicle controller and vehicle control method

A vehicle controller configured to control a hybrid electric vehicle that includes a hybrid system as a drive source, the hybrid system including an engine and a motor generator, wherein

• the hybrid system includes a clutch disposed between an output shaft of the engine and a rotary shaft of the motor generator and is configured to extract drive force from the rotary shaft of the motor generator,
• the engine includes a catalyst configured to purify exhaust gas of the engine,
• the hybrid electric vehicle has two traveling modes that include an electric traveling mode, in which the hybrid electric vehicle travels with the engine in a stopped state and the clutch disengaged, and a hybrid traveling mode, in which the hybrid electric vehicle travels with the clutch engaged,
• the vehicle controller includes processing circuitry,
• the processing circuitry is configured to, when the traveling mode is switched from the electric traveling mode to the hybrid traveling mode,
• set a throttle opening degree of the engine to a specified starting opening degree until an elapsed time from a restart of the engine reaches a specified partial activation determination value, the specified partial activation determination value being set to a time shorter than a predicted value of a required time from the restart of the engine to completion of engagement of the clutch, and
• set the throttle opening degree to a specified-amount opening degree, at which an intake air amount of the engine is constant in relation to an atmospheric pressure, until the elapsed time from the restart of the engine reaches a specified activation completion determination value after exceeding the specified partial activation determination value, the specified activation completion determination value being set to a time longer than the predicted value, and
• the processing circuitry is configured to set the specified-amount opening degree so as to obtain the intake air amount that satisfies a requirement that the engine discharges the exhaust gas in an amount purifiable by the catalyst in a partially activated state.