Misfire determination apparatus

A misfire determination apparatus comprising:

• a first obtaining unit configured to obtain actual engine rotation number, the actual engine rotation number being actual number of rotation of an engine in a hybrid electric vehicle, the engine being coupled to side of an axle via a torsion element in the hybrid electric vehicle, the axle being coupled to an electric motor in a torque transmittable manner in the hybrid electric vehicle;
• a second obtaining unit configured to obtain motor rotation number, the motor rotation number being number of rotation of the electric motor;
• a calculator configured to calculate calculated engine rotation number on a basis of the motor rotation number and a total gear ratio between the electric motor and the engine, the calculated engine rotation number being calculated number of the rotation of the engine;
• a third obtaining unit configured to obtain a rotation deviation between the actual engine rotation number and the calculated engine rotation number;
• and
• a determination unit configured to execute misfire determination of the engine by determining the engine as being misfiring when the rotation deviation exceeds a determination threshold.