Control system for hybrid vehicles

A control system for a hybrid vehicle, comprising:

• a differential mechanism including a first rotary member connected to an engine, a second rotary member connected to a rotary machine, and a third rotary member connected to drive wheels;
• a battery that supplies electric power to the rotary machine and that is charged with electric power generated by the rotary machine,
• wherein the differential mechanism is adapted to establish a first electric vehicle mode in which a ratio of a rotational speed of the drive wheel to a rotational speed of the rotary machine becomes a first predetermined value, and a second electric vehicle mode in which said ratio becomes a second predetermined value that is greater than the first predetermined value, and
• a controller that selects an electric vehicle mode from the first electric vehicle mode and the second electric vehicle mode,
• wherein the controller is configured to:
• crank the engine by operating the rotary machine to generate a torque in such a manner as to reduce a rotational speed of the rotary machine when shifting the operating mode from the first electric vehicle mode or the second electric vehicle mode to a hybrid mode in which the hybrid vehicle is propelled by generating a drive torque by the engine while establishing a reaction torque by the rotary machine;
• calculate a peak power, that is a maximum value of an input power to the battery from the rotary machine during a period from a commencement of the cranking of the engine to a termination of the cranking of the engine, to start the engine to shift the operating mode from the first electric vehicle mode to the hybrid mode;
• determine whether or not the peak power is greater than an upper limit input power to the battery;
• and
• shift the operating mode from the first electric vehicle mode to the second electric vehicle mode if the peak power is greater than an upper limit input power to the battery;
• and
• a brake that applies a negative torque to the first rotary member to reduce a rotational speed of the first rotary member,
• wherein the controller is further configured to:
• establish the first electric vehicle mode and the second electric vehicle mode by applying the negative torque to the first rotary member by the brake, and
• crank the engine by reducing the negative torque applied to the first rotary member by the brake while operation the rotary machine to generate a torque in such a manner as to reduce a rotational speed of the rotary machine, when shifting the operating mode from the first electric vehicle mode or the second electric vehicle mode to the hybrid mode.