Exhaust heat recovery device

Patent metadata

Field	Value
Publication number	US-9957845-B2
Application number	US-201414780614-A
Country	US
Kind code	B2
Filing date	Mar 26, 2014
Priority date	Mar 28, 2013
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

To effectively reduce a situation in which an over-rotation of an expander occurs or the expander becomes a load on an engine at the time of a stop of a Rankine cycle in an exhaust heat recovery device provided with the Rankine cycle that recovers exhaust heat of an engine. A pressure difference ΔP between a high-pressure side and a low-pressure side of the Rankine cycle is obtained when the Rankine cycle is stopped (S 1 ), a waiting time Ta is set (calculated) based on the obtained pressure difference ΔP (S 2 ). Then, a bypass valve is opened to allow a refrigerant to circulate while bypassing the expander (S 3 ), and then an electromagnetic clutch is disengaged when the waiting time Ta has elapsed to block transmission of power between the expander and the engine (S 4 , S 5 ).

First claim

The invention claimed is:

1. An exhaust heat recovery device comprising:
a Rankine cycle that is provided with: a heater configured to heat and vaporize refrigerant by exhaust heat of an engine; an expander configured to expand the refrigerant passed through the heater to generate power; 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, the heater, the expander, the condenser, and the pump being arranged in a refrigerant circulating passage;
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 power transmission mechanism that has a clutch mechanism and is capable of transmitting power between the expander and the engine when the clutch mechanism is engaged; and
a control unit that, at the time of stopping the Rankine cycle, executes control to open the bypass valve and then to disengage the clutch mechanism when a waiting time has elapsed, the waiting time being set depending on operation states or operation conditions of the Rankine cycle before the bypass valve is opened or at the point of time when the bypass valve is opened.

2. The exhaust heat recovery device according to claim 1 , wherein the waiting time is calculated by multiplying a value indicating the operation states or the operation conditions by a predetermined coefficient.

3. The exhaust heat recovery device according to claim 2 , further comprising a pressure difference obtaining unit that obtains a pressure difference between a high-pressure side and a low-pressure side of the Rankine cycle,
wherein the pressure difference between the high-pressure side and the low-pressure side of the Rankine cycle is used as the value indicating the operation states or the operation conditions.

4. The exhaust heat recovery device according to claim 2 , further comprising a pressure measuring unit that measures a pressure of a high-pressure side of the Rankine cycle,
wherein the pressure of the high-pressure side of the Rankine cycle is used as the value indicating the operation states or the operation conditions.

5. The exhaust heat recovery device according to claim 2 , wherein the exhaust heat recovery device is mounted on a vehicle, and a vehicle speed is used as the value indicating the operation states or the operation conditions.

6. The exhaust heat recovery device according to claim 1 , wherein the control unit sets the waiting time based on a temperature of ambient air.

7. The exhaust heat recovery device according to claim 1 , further comprising a rotational number measuring unit that measures a rotational number of the expander,
wherein in a case in which an over-rotation of the expander, in which the rotational number of the expander exceeds a predetermined rotational number, occurs after the clutch mechanism is disengaged, the control unit corrects the waiting time by extending the waiting time in the next stop of the Rankine cycle.

8. The exhaust heat recovery device according to claim 1 , wherein when a stop operation of the engine is executed during the operation of the Rankine cycle, the control unit executes control to open the bypass valve immediately, and then controls to disengage the clutch mechanism when a second waiting time has elapsed, the second waiting time being shorter than the waiting time.

9. The exhaust heat recovery device according to claim 1 , wherein the expander and the pump in the Rankine cycle are integrally connected to each other.

Assignees

• Sanden Holdings Corp

Inventors

• Haraguchi Tomonori
• Nagai Hiroyuki

Classifications

• F02G5/00

  Profiting from waste heat of combustion engines, not otherwise provided for · CPC title

• Y02T10/166

  Cross-Sectional Technologies · mapped topic

• F01K23/101

  Regulating means specially adapted therefor (F01K23/105, F01K23/108 take precedence) · CPC title

• F01K23/065 Primary

  the combustion taking place in an internal combustion piston engine, e.g. a diesel engine · CPC title

• F01K25/10

  the vapours being cold, e.g. ammonia, carbon dioxide, ether · CPC title