Waste heat utilization apparatus for internal combustion engine

A waste heat utilization apparatus for an internal combustion engine, comprising:

• a Rankine circuit including a circulation path for circulating a working fluid, a plurality of heat exchangers for heating the working fluid with use of waste heat of the internal combustion engine, an expander for expanding the working fluid supplied thereto via the plurality of heat exchangers to generate rotary driving force, a condenser for condensing the working fluid supplied thereto via the expander, and a pump for delivering the working fluid supplied thereto via the condenser to the heat exchangers, wherein the plurality of heat exchangers, the expander, the condenser and the pump are sequentially inserted in the circulation path;
• an exhaust gas heat exchanger inserted in an exhaust passage through which exhaust gas of the internal combustion engine is emitted to atmosphere;
• an EGR circuit including an EGR passage for recirculating part of the exhaust gas as EGR gas to an intake side of the internal combustion engine, an EGR valve inserted in the EGR passage and opened and closed at least in accordance with an operating condition of the internal combustion engine, to permit and block recirculation of the EGR gas, and an EGR cooler inserted in the EGR passage to cool the EGR gas;
• an EGR gas temperature detector arranged in the EGR passage at a location downstream of the EGR cooler, as viewed in a flowing direction of the EGR gas, to detect temperature of the EGR gas;
• and
• a control unit configured to control an amount of heat transferred from the EGR gas in the EGR cooler at least while the EGR valve is opened to permit the recirculation of the EGR gas,
• wherein the plurality of heat exchangers of the Rankine circuit are the EGR cooler and the exhaust gas heat exchanger and are configured such that the EGR cooler is located upstream of the exhaust gas heat exchanger as viewed in the flowing direction of the working fluid in the circulation path, that the working fluid is heated in the EGR cooler with use of heat of the EGR gas, and that the working fluid is heated in the exhaust gas heat exchanger with use of heat of the exhaust gas, and
• wherein the control unit controls the amount of heat transferred from the EGR gas to the working fluid in the EGR cooler such that the temperature of the EGR gas detected by the EGR gas temperature detector falls within a predetermined temperature range.