Waste heat utilization device for internal combustion engine

摘要

Control means (32) that controls the actuation of Rankine cycle (8) is provided. An evaporator (10) is capable of absorbing heat from the waste heat of the internal combustion engine (4) with an upper limit of preset maximum heat absorption amount and transferring the heat to working fluid. The control means (32) controls the flow rate of the working fluid so that the working fluid evaporated by the evaporator (10) comes into a superheated state in a heater (18), when the working fluid enters the evaporator (10) at a flow rate equal to or lower than preset flow rate at which the working fluid can absorb the preset maximum heat absorption amount of heat, and controls the flow rate of the working fluid so that the working fluid that overflows the evaporator (10) is evaporated by the heater (18) and then comes into the superheat state, when the working fluid enters the evaporator (10) at a flow rate higher than the preset flow rate.

主权项

1. A waste heat utilization device for an internal combustion engine, comprising:
a Rankine cycle including an evaporator that evaporates and superheats a working fluid by using waste heat of an internal combustion engine, a superheater that further superheats the working fluid leaving the evaporator by using the waste heat of the internal combustion engine, an expander that expands the working fluid discharged from the superheater and generates a driving force, a condenser that condenses the working fluid discharged from the expander, and a pump that delivers to the evaporator the working fluid discharged from the condenser; and an electrical control unit configured to control actuation of the Rankine cycle such that the electrical control unit conducts flow rate control of the working fluid by: (a) reducing a rotation frequency of the pump when an expander inlet temperature of the working fluid entering the expander is lower than a preset expander inlet temperature and a superheat level of the working fluid in the evaporator is equal to or lower than a preset superheat level, thereby making the working fluid into high-pressure gas obtained by evaporating and superheating the working fluid in the evaporator, and making the high-pressure gas further superheat in the superheater, and (b) increasing the rotation frequency of the pump during the flow rate control to increase a flow rate of the working fluid flowing into the evaporator when the working fluid entering the expander has an expander inlet temperature equal to or higher than said preset expander inlet temperature, thereby allowing a liquid-phase working fluid that fails to evaporate in the evaporator to overflow the evaporator, and evaporating and superheating in the superheater the liquid-phase working fluid that failed to be fully evaporated by the evaporator.