Patent ID: 8250869

Claim:
An exhaust heat recovery apparatus, comprising: an exhaust heat recovery device that produces motive power by recovering thermal energy from exhaust gas from a heat engine, wherein the produced motive power is output together with motive power produced by the heat engine; and a rotation speed ratio-changing device including a processor and a memory storing a program executed by the processor to perform a method of setting a rotation speed ratio, the method comprising when an increase in the rotation speed of the exhaust heat recovery device lags behind an increase in the rotation speed of the heat engine, setting the ratio of the rotation speed of the exhaust heat recovery device to the rotation speed of the heat engine smaller than that when the increase in the rotation speed of the exhaust heat recovery device follows the increase in the rotation speed of the heat engine, wherein the increase in the rotation speed of the exhaust heat recovery device is considered being lag behind the increase in the rotation speed of the heat engine if it is determined that an acceleration requires rapid acceleration, whereas an increase in the rotation speed of the exhaust heat recovery device is not considered being lag behind an increase in the rotation speed of the heat engine if it is determined that an acceleration does not require rapid acceleration, and wherein an acceleration is considered being a rapid acceleration if the estimated acceleration of the exhaust heat recovery apparatus is lower than the required acceleration of the heat engine, and maintaining the smaller rotation speed ratio for a predetermined time period.