Exhaust heat recovery device

Abstract

An exhaust heat recovery device includes an evaporator disposed to evaporate a working fluid by exchanging heat between a heating fluid and the working fluid, a condenser disposed to cool and condense the working fluid by exchanging heat between a fluid to be heated and the working fluid evaporated by the evaporator, an evaporation side connection portion for guiding the working fluid evaporated by the evaporator to the condenser, and a condensation side connection portion for guiding the working fluid condensed by the condenser to the evaporator. Furthermore, at least one of the evaporation side connection portion and the condensation side connection portion has a curved portion.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on Japanese Patent Applications No. 2007-170078 filed on Jun. 28, 2007, and No. 2008-034082 filed on Feb. 15, 2008, the contents of which are incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates to an exhaust heat recovery device used for a vehicle.BACKGROUND OF THE INVENTION[0003]In recent years, techniques have been known which are adapted to recover heat of an exhaust gas from an exhaust gas system of an engine of a vehicle using the principle of a heat pipe, so as to use the recovered exhaust heat for promotion of warming or the like. Such an exhaust heat recovery device includes an evaporator of the heat pipe disposed in an exhaust pipe of the engine and a condenser of the heat pipe disposed in a coolant passage of the engine. Furthermore, the exhaust heat recovery device is configured to heat coolant of the engine by the exhaust heat of the exhaust gas (s...

AI Technical Summary

Benefits of technology

[0008]The invention has been made in view of the foregoing problems, and it is an object of the invention to provide an exhaust heat recovery device that can release thermal stress with a simple structure, while preventing occurrence of holes due to external corrosion.

[0010]In this way, at least one of the evaporation side connection portion and the condensation side connection portion has a part (or the whole) thereof curved. When a difference in temperature between the evaporator and the condenser is generated, an elastic deformation of the curved portion can absorb thermal stress caused by a difference in thermal expansion. At this time, bellows do not need to be provided in the evaporation side and condensation side connection portions, thereby releasing the thermal stress with a simple structure while preventing the occurrence of holes due to external corrosion.

[0011]In the exhaust heat recovery device, the working fluid evaporated by the evaporator flows into the condenser through the evaporation side connection portion. The condensed liquid fluid flows into the evaporator through the condensation side connection portion. Thus, there occurs a difference in water level (water head) of the working fluid (liquid) between the evaporator and the condenser, depending on a balance between evaporation of the working fluid at the evaporator and condensation of the working fluid at the condenser. The difference in water head allows the working fluid to be refluxed from the condenser to the evaporator, thereby causing the circulation of the working fluid.

Problems solved by technology

The difference in temperature between the evaporator J1 and the condenser J2 may disadvantageously cause thermal stress due to a difference in thermal expansion between the evaporation side connection portion J71 and the condensation side connection portion J72.

The structure, however, may be complicated, resulting in high manufacturing cost.

This may cause holes in the bellows due to corrosion from an external side, that is, from the side in contact with atmosphere.

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