HYBRID VEHICLE CONTROL METHOD AND HYBRID VEHICLE CONTROL DEVICE

A hybrid control method of the present invention involves controlling a hybrid vehicle in which when an internal combustion engine is in a firing state, power is generated by an electric power generation motor connected to an internal combustion engine via a gear mechanism, and assistance is performed using intake negative pressure of the internal combustion engine during brake actuation. In this hybrid control method, a control unit sets, as a rotational speed threshold value, an engine rotational speed at which gear tooth striking sound occurring in the gear mechanism in the firing state is not a problem in terms of quality, and generates negative pressure while maintaining the engine rotational speed in the firing state when negative pressure must be generated in the firing state with the engine rotational speed equal to or greater than the rotational speed threshold value. In addition, the control unit generates negative pressure after switching from the firing state to a motoring state, in which the internal combustion engine is caused to rotate by the electric power generation motor, when negative pressure must be generated in the firing state with the engine rotational speed less than the rotational speed threshold value.