Engine start control device

An engine start control device for a hybrid vehicle, comprising:

• a battery for a driving;
• a first rotary electric machine and a second rotary electric machine configured to work by consuming an electric power of the battery;
• an engine configured to start up with the first rotary electric machine;
• a first determination unit configured to determine whether a maximum output of the battery is in a low output state that is lower than a predetermined lower limit value;
• a cranking control unit configured to perform a cranking of the engine by running the first rotary electric machine when the hybrid vehicle transitions from an EV mode in which the hybrid vehicle is powered by at least one of the first rotary electric machine and the second rotary electric machine to travel only with the electric power of the battery, to a start mode in which the engine is started;
• a second determination unit configured to determine whether the cranking is completed;
• and
• an injection control unit configured to start a fuel injection of the engine in response to the second determination unit determining that the cranking is completed, wherein
• in a case where the first determination unit determines that the maximum output of the battery is in the low output state, the cranking control unit causes the first rotary electric machine to run at a target rotation speed lower than a target rotation speed of the cranking in a normal state different from the low output state,
• in a case where the first determination unit determines that the maximum output of the battery is in the low output state, the second determination unit determines that the cranking is completed when a condition that an actual rotation speed of the first rotary electric machine during the cranking continues to be within a preset target range for a predetermined time is satisfied,
• the engine start control device further comprises:
• a torque control unit that controls a torque of the first rotary electric machine by a feedback control using a difference between the target rotation speed and the actual rotation speed of the first rotary electric machine during the cranking, and
• in a case where the first determination unit determines that the maximum output of the battery is in the low output state, the torque control unit sets a feedback term used for calculating a target value of the torque to zero or more.