Catalyst warm-up control method for internal combustion engine, and catalyst warm-up control device

A catalyst warm-up control method for an internal combustion engine,

• the internal combustion engine being mounted for power generation in a series hybrid vehicle and being controllable to be started or stopped according to a power generation request from a vehicle side, the internal combustion engine comprising an exhaust system having a first catalyst in an upstream side thereof and a second catalyst on a downstream side thereof,
• the catalyst warm-up control method comprising:
• after starting of the internal combustion engine, detecting or estimating catalyst warm-up states of the respective first and second catalysts;
• and
• until judging completion of warm-up of the first and second catalysts, continuing operation of the internal combustion engine, without stopping the internal combustion engine, both (i) when the power generation request is provided and (ii) when the power generation request ceases,
• wherein the internal combustion engine is operated with ignition timing retardation for catalyst warm-up during a first period from the starting of the internal combustion engine to the completion of the warm-up of the first catalyst, and is operated without ignition timing retardation during a second period from the completion of the warm-up of the first catalyst to the completion of the warm-up of the second catalyst.