Exhaust heat recovery device

An exhaust heat recovery device comprising:

• a Rankine cycle in which a heater configured to heat and vaporize refrigerant by exhaust heat of an external heat source, an expander configured to generate power by expanding the refrigerant passed through the heater, a condenser configured to condense the refrigerant passed through the expander, and a pump configured to send the refrigerant passed through the condenser to the heater are disposed in a circulation passage of the refrigerant;
• a bypass flow passage that allows the refrigerant to circulate while bypassing the expander;
• a bypass valve that opens and closes the bypass flow passage;
• a pressure difference determining unit that determines a pressure difference between a high-pressure side and a low-pressure side of the Rankine cycle;
• and
• a control unit that executes start-up control of the Rankine cycle, the start-up control actuating the pump with the bypass valve open and then closing the bypass valve,
• wherein the control unit repeatedly executes the start-up control when the pressure difference after closing the bypass valve does not reach a start-up completion determination value of the Rankine cycle within a predetermined time, and
• wherein the control unit executes, as the start-up control, control to actuate the pump with the bypass valve open, and then to close the bypass valve when the pressure difference becomes a valve-closing determination value or more, the valve-closing determination value being less than the start-up completion determination value.

An exhaust heat recovery device comprising:

• a Rankine cycle in which a heater configured to heat and vaporize refrigerant by exhaust heat of an external heat source, an expander configured to generate power by expanding the refrigerant passed through the heater, a condenser configured to condense the refrigerant passed through the expander, and a pump configured to send the refrigerant passed through the condenser to the heater are disposed in a circulation passage of the refrigerant;
• a bypass flow passage that allows the refrigerant to circulate while bypassing the expander;
• a bypass valve that opens and closes the bypass flow passage;
• a pressure difference determining unit that determines a pressure difference between a high-pressure side and a low-pressure side of the Rankine cycle;
• and
• a control unit that, when starting up the Rankine cycle, executes control to actuate the pump with the bypass valve open, and then to close the bypass valve when the pressure difference becomes a predetermined value,
• wherein the control unit executes control to open the bypass valve when the pressure difference does not reach a start-up completion determination value greater than a first predetermined value within a predetermined time after closing the bypass valve when the pressure difference becomes the first predetermined value, and then to close the bypass valve when the pressure difference becomes a second predetermined value greater than the first predetermined value and less than the start-up completion determination value.