Exhaust heat recovery device

Abstract

An exhaust heat recovery device able to secure heat exchange performance even when tilted, provided with an evaporator exchanging heat between an exhaust gas and an evaporable and condensable working fluid sealed inside it and thereby evaporating the working fluid and a condenser exchanging heat between the working fluid evaporated by the evaporator and the cooling water and thereby condensing the working fluid, wherein the evaporator and condenser are arranged in a closed loop channel through which the working fluid circulates, the evaporator and condenser are arranged adjoining each other in the substantially horizontal direction, the evaporator is provided with a plurality of evaporation side heat pipes arranged in parallel and is provided with a first evaporation side header communicating one ends of the plurality of evaporation side heat pipe and a second evaporation side header communicating the other ends, and, when mounted in a vehicle in a horizontal state, the second evaporation side header arranged at the bottom among the two evaporation side headers is arranged with the side far from the condenser positioned lower than the side close to it.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:

FIG. 1 is a cross-sectional view showing an exhaust heat recovery device according to a first embodiment;

FIG. 2 is a cross-sectional view showing an exhaust heat recovery device according to a second embodiment;

FIG. 3 is a cross-sectional view showing an exhaust heat recovery device according to a third embodiment;

FIG. 4 is an enlarged cross-sectional view of a part A of FIG. 3;

FIG. 5 is a cross-sectional view showing an exhaust heat recovery device according to a fourth embodiment;

FIG. 6 is a cross-sectional view showing an exhaust heat recovery device according to a fifth embodiment;

FIG. 7 is a cross-sectional view showing a conventional exhaust heat recovery device;

FIG. 8 is a cross-sectional view showing the state of a conventional exhaust heat recovery device tilted with respect to the horizontal direction; and

FIG. 9 is a cross-sectional view showing the state of an exhaust heat recovery device having a conventional valve mechanism J6 tilted with respect to the horizontal direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Below, a first embodiment of the present invention will be explained based on FIG. 1. The exhaust heat recovery device of the present embodiment recovers the exhaust heat of the exhaust gas from the exhaust system of the engine of a vehicle (internal combustion engine) and utilizes this exhaust heat for assisting warmup.

FIG. 1 is a cross-sectional view showing an exhaust heat recovery device according to the first embodiment. As shown in FIG. 1, the exhaust heat recovery device of the present embodiment is provided with an evaporator 1 and condenser 2.

The evaporator 1 is provided inside a first housing 100 arranged in an exhaust pipe of a not shown engine. Further, the evaporator 1 performs heat exchange between the exhaust gas and the later explained working fluid and evaporates the working fluid.

The condenser 2 is provided outside the exhaust pipe and is provided inside a second housing 200 arranged in the cooling water passage of a not shown engine. Further, the condenser 2 exchanges heat between the working fluid evaporated by the evaporator 1 and the engine cooling water to condense the working fluid. The second housing 200 is provided with a cooling water inflow port 201 connected to the cooling water outlet side of the engine and a cooling water outflow port 202 connected to the cooling water inlet side of the engine.

The evaporator 1 and condenser 2 are arranged adjoining each other in the horizontal direction. Normally, an exhaust pipe (not shown) is provided across the front-rear direction of the vehicle, so the directions of arrangement of the evaporator 1 and condenser 2 match in the vehicle width direction.

Next, the configuration of the evaporator 1 will be explained.

The evaporator 1 has a plurality of evaporation side heat pipes 3a and corrugated fins 4a bonded to the outer surfaces of the evaporation side heat pipes 3a. The evaporation side heat pipes 3a are formed flattened so that the direction of circulation of the exhaust gas (direction vertical to paper surface) matches with the long diameter direction and are arranged in parallel so that their longitudinal directions match with the vertical direction.

In the evaporator 1, at the two ends of the evaporation side heat pipes 3a in the longitudinal direction, evaporation side headers 5a extending in the stacking direction of the evaporation side heat pipes 3a and communicating with all evaporation side heat pipes 3a are provided. The evaporation side header 5a arranged at the top end of the exhaust heat recovery device among the evaporation side headers 5a will be referred to as the “first evaporation side header 51a”, while the evaporation side header 5a arranged at the bottom will be referred to as the “second evaporation side header 52a”. Note that first evaporation side header 51a corresponds to the first communicating part of the present invention, while the second evaporation side header 52a corresponds to the second communicating part.

Next, the configuration of the condenser 2 will be explained.

The condenser 2 has a plurality of condensation side heat pipes 3b. The condensation side heat pipes 3b are formed flattened so that the direction of circulation of the engine cooling water (direction vertical to paper surface) matches with the long diameter direction and are arranged in parallel so that their longitudinal directions match with the vertical direction.

In the condenser 2, at the two ends of the condensation side heat pipes 3b in the longitudinal direction, condensation side headers 5b extending in the stacking direction of the condensation side heat pipes 3b and communicating with all condensation side heat pipes 3b are provided. Among the condensation side headers 5b, the condensation side header 5b arranged at the top end side of the exhaust heat recovery device in the vertical direction will be called the “first condensation side header 51b”, while the condensation side header 5b arranged at the bottom end side in the vertical direction will be called the “second condensation side header 52b”.

The evaporation side headers 5a and the condensation side headers 5b are connected in a communicable state. Further, the evaporation side and condensation side heat pipes 3a, 3b and evaporation side condensation side headers 5a, 5b form a closed loop. Water, alcohol, or another evaporable and condensable working fluid is sealed inside these.

Further, the second condensation side header 52b has a valve mechanism 6 provided inside it. The valve mechanism 6 forms a diaphragm type switching means for forming a channel connecting the condensation side heat pipes 3b and second evaporation side header 52a and switching channels in accordance with the internal pressure of the evaporation side heat pipes 3a (pressure of working fluid). Specifically, the valve mechanism 6 is configured to close from the usual open state when the internal pressure rises and exceeds a first predetermined pressure at a predetermined cooling water temperature and conversely to open again when the internal pressure falls and becomes less than a second predetermined pressure lower than the first predetermined pressure.

In the present embodiment, the second evaporation side header 52a is arranged tilted with respect to the horizontal direction so that a portion at a side far from the condenser 2 becomes lower than the portion at the side close to the condenser 2 when the vehicle in which the exhaust heat recovery device is carried is positioned on a horizontal road surface. The bottom ends of the evaporation side heat pipes 3a at the side far from the condenser 2 are positioned lower than the bottom ends of the evaporation side heat pipes 3a at the side close to the condenser 2. In the present embodiment, the tilt angle θ of the second evaporation side header 52a with respect to the horizontal direction becomes 3° to 20° in range. Further, the first evaporation side header 51a is arranged so as not to be tilted, that is, with a longitudinal direction (stacking direction of evaporation side heat pipes 3a) matching with the horizontal direction.

As explained above, by arranging the second evaporation side header 52a tilted in advance so that the portion at the side far from the condenser 2 becomes lower than the portion at the side close to the condenser 2, it is possible to suppress the reduction of the water head difference between the evaporator 1 and condenser 2 when the evaporator 1 is tilted so as to become higher than the condenser 2. Due to this, even when tilted, a sufficient amount of working fluid can be refluxed from the condenser 2 to the evaporator 1, so the heat exchange performance can be secured.

Further, in the present embodiment, the second condensation side header 52b is provided inside it with a valve mechanism 6 for controlling the flow of the working fluid from the condenser 2 to the evaporator 1. In this case, pressure loss occurs in the valve mechanism 6, so when the exhaust heat recovery device is tilted so that the evaporator 1 becomes higher than the condenser 2, it becomes hard for the working fluid to be refluxed well from the condenser 2 to the evaporator 1. Therefore, when providing the valve mechanism 6, such a configuration (second evaporation side header 52a arranged tilted so that the part at the side far from the condenser 2 becomes lower than the part at the side close to the condenser 2) can be said to be more effective.

Note that the usually envisioned tilt angle of a road surface in the vehicle width direction is not more than 20°. For this reason, by making the tilt angle θ of the second evaporation side header 52a with respect to the horizontal direction 3° to 20° in range, it is possible to handle the usually envisioned range of tilt of a road surface.

Second Embodiment

Next, a second embodiment of the present invention will be explained based on FIG. 2. Parts similar to those in the first embodiment are assigned the same reference numerals and explanations will be omitted.

FIG. 2 is a cross-sectional view showing an exhaust heat recovery device according to the second embodiment. As shown in FIG. 2, the evaporation side headers 5a and the condensation side headers 5b are connected in a communicable state through tubular connecting parts 7. Further, the evaporation side and condensation side heat pipes 3a, 3b, evaporation side and condensation side headers 5a, 5b, and connecting parts 7 form a closed loop. Water, alcohol, or another evaporable and condensable working fluid is sealed inside these.

Further, the evaporator 1 is arranged tilted with respect to the horizontal direction so that the part at the side far from the condenser 2 becomes lower than the part at the side close to the condenser 2 when the exhaust heat recovery device is carried in a vehicle in the horizontal state. At that time, in the evaporation side headers 5a, the ends at the sides far from the condenser 2 become lower than the ends at the sides close to the condenser 2. That is, the bottom ends of the evaporation side heat pipes 3a at the side far from the condenser 2 are positioned below the bottom ends of the evaporation side heat pipes 3a at the side close to the condenser 2. Note that in the present embodiment, the first housing 100 is arranged tilted by a tilt angle θ similar to the evaporator 1.

The end of the bottom surface 110 (lower surface) of the first housing 100 at the side far from the condenser 2 is formed with a condensed water catch 111 able to store the exhaust condensed water. Note that the “exhaust condensed water” means the water generated due to condensation of the moisture contained in the exhaust gas due to the exhaust gas being rapidly cooled in the evaporator 1 right after engine startup when the temperature of the evaporator 1 is low. The first housing 100 is tilted with respect to the horizontal direction so that the side far from the condenser 2 becomes lower, so the exhaust condensed water flows toward the condensed water catch 111. Due to this, the exhaust condensed water can be stored in one location, so discharge of the exhaust condensed water becomes easy.

As explained above, when arranging the second evaporation side header 52a tilted in advance so that the portion of the side far from the condenser 2 becomes lower than the portion at the side close to the condenser 2 to thereby make the evaporator 1 become higher than the condenser 2, the water head difference between the evaporator 1 and condenser 2 can be kept from becoming smaller. Due to this, effects similar to those of the first embodiment can be obtained.

Third Embodiment

Next, a third embodiment of the present invention will be explained based on FIG. 3 and FIG. 4. Parts similar to those in the first embodiment are assigned the same reference numerals and explanations will be omitted.

FIG. 3 is a cross-sectional view showing an exhaust heat recovery device according to the third embodiment, while FIG. 4 is an enlarged cross-sectional view of a part A of FIG. 3. As shown in FIG. 3 and FIG. 4, the evaporation side heat pipes 3a of the present embodiment are formed by pairs of shaped plates 31, 32 mating in cross-section along the longitudinal direction. The pairs of shaped plates 31, 32 are formed into dish shapes (cross-sectional U-shapes).

The two end sides of the pairs of shaped plates 31, 32 in the longitudinal direction are formed with pairs of tubular flange parts 33 projecting out in the opposite directions toward the outsides of the evaporation side heat pipes 3a. One flange part 33 of each pair of flange parts 33 has a larger open size than the other flange part 33. For this reason, the end of one flange part 33 fits into the end of another flange part 33 for engagement.

The evaporation side headers 5a are formed by stacking the flange parts 33 of the evaporation side heat pipes 3a and the longitudinal direction ends of the evaporation side heat pipes 3a and are communicated with each other by the engagement of the ends of the adjoining flange parts 33.

In the present embodiment, the adjoining evaporation side heat pipes 3a are arranged offset from each other in the vertical direction. More specifically, in adjoining evaporation side heat pipes 3a, the evaporation side heat pipe 3a at the side far from the condenser 2 is positioned lower than the evaporation side heat pipe 3a at the side close to the condenser 2.

At that time, the channels formed by adjoining pairs of flange parts 33 in the evaporation side headers 5a (hereinafter referred to as the “header component members 34”) are arranged in steps. More specifically, in the adjoining header component members 34, the header component member 34 at the side far from the condenser 2 is arranged so as to be lower than the header component member 34 at the side close to the condenser 2. Therefore, the evaporation side headers 5a are arranged so that the end in the vehicle width direction at the side far from the condenser 2 becomes lower than the end of the side close to the condenser 2.

Due to this, effects similar to those of the first embodiment can be obtained.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be explained based on FIG. 5. Parts similar to those in the third embodiment are assigned the same reference numerals and explanations will be omitted.

FIG. 5 is a cross-sectional view showing an exhaust heat recovery device according to the fourth embodiment. As shown in FIG. 5, the first evaporation side headers 51a of the present embodiment are arranged in parallel in the horizontal direction. More specifically, the first evaporation side headers 51a are arranged so that their longitudinal directions (stacking directions of evaporation side heat pipes 3a) match in the horizontal direction. At that time, in the plurality of evaporation side heat pipes 3a, the closer to the condenser 2, the longer the length in the longitudinal direction.

Due to this, effects similar to those of the third embodiment can be obtained.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be explained based on FIG. 6. Parts similar to those in the first embodiment are assigned the same reference numerals and explanations will be omitted.

FIG. 6 is a cross-sectional view showing an exhaust heat recovery device according to the fifth embodiment. As shown in FIG. 6, in the present embodiment, second evaporation side headers 51a, 52a are arranged in parallel in the horizontal direction. Further, corrugated fins 4b are bonded to the outer surfaces of the condensation side heat pipes 3b.

Further, the evaporation side headers 5a and the condensation side headers 5b are connected in a communicating state through tubular connecting parts 7. Further, the evaporation side and condensation side heat pipes 3a, 3b, evaporation side and condensation side headers 5a, 5b, and connecting parts 7 form a closed loop. Water, alcohol, or another evaporable and condensable working fluid is sealed inside these. Due to this, the working fluid circulates through the evaporator 1 and condenser 2.

Here, among the two connecting parts 7, the one arranged at the top side, connecting the first evaporation side header 51a and first condensation side header 51b, and guiding working fluid evaporated at the evaporator 1 to the condenser 2 will be called the “evaporation side connecting part 71”. Further, among the two connecting parts 7, the one arranged at the bottom side, connecting the second evaporation side header 52a and second condensation side header 52b, and guiding the working fluid condensed at the condenser 2 to the evaporator 1 will be called the “condensation side connecting part 72”.

In the present embodiment, the second condensation side header 52b is arranged so that it becomes higher than the second evaporation side header 52a when the exhaust heat recovery device is mounted in a vehicle in the horizontal state. Further, at the condensation side connecting part 72, the end at the condenser 2 side is connected to the second condensation side header 52b, while the end at the evaporator 1 side is connected to the heat pipe 30a at the side closest to the condenser 2 among the plurality of evaporation side heat pipes 3a.

Further, the condensation side connecting part 72 is arranged tilted with respect to the horizontal direction so that the portion of the side far from the condenser 2 becomes lower than the portion of the side close to the condenser 2 when the exhaust heat recovery device is mounted in a vehicle in the horizontal state. That is, the condensation side connecting part 72 is tilted with respect to the horizontal direction so as to become lower from the condenser 2 side toward the evaporator 1 side. In the present embodiment, the tilt angle θ of the condensation side connecting part 72 with respect to the horizontal direction is made 3° to 20° in range.

As explained above, by tilting the condensation side connecting part 72 in advance so that the portion at the side far from the condenser 2 becomes lower than the portion at the side close to the condenser 2, when the exhaust heat recovery device as a whole is tilted so that the evaporator 1 becomes higher than the condenser 2, the water head difference between the evaporator 1 and the condenser 2 can be kept from becoming smaller. Due to this, even when tilted, a sufficient amount of working fluid can be refluxed from the condenser 2 to the evaporator 1, so the heat exchange performance can be secured. Further, when the exhaust heat recovery device as a whole is tilted so that the evaporator 1 becomes higher than the condenser 2, it is possible to prevent working fluid from ending up remaining in the condensation side connecting part 72. For this reason, blockage or breakage of the condensation side connecting part 72 under a low temperature environment can be prevented.

However, the tilt angle in the vehicle width direction of a road surface usually envisioned is not more than 20°. For this reason, by making the tilt angle θ of the condensation side connecting part 72 with respect to the horizontal direction 3° to 20° in range, it is possible to deal with the usually envisioned range of tilt of a road surface.

Other Embodiments

Note that in the above embodiments, the condenser 2 was configured with a plurality of condensation side heat pipes 3b arranged in parallel so that their longitudinal directions matched with the vertical direction, but the invention is not limited to this. The condenser 2 may be configured in any way.

Further, in the second embodiment, the first housing 100 was provided with a condensed water catch 111, but this need not be provided.

Further, in the third and fourth embodiments, the evaporation side heat pipes 3a were formed from pairs of shaped plates 31, 32 mating in cross-section along the longitudinal direction, but the evaporation side heat pipes 3a need not be split.

While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.

Claims

1. An exhaust heat recovery device carried in a vehicle using an internal combustion engine as a drive source for operation and provided with an evaporator arranged in an exhaust gas passage through which exhaust gas exhausted from the internal combustion engine runs, exchanging heat between the exhaust gas and an evaporable and condensable working fluid sealed inside it, and thereby evaporating the working fluid anda condenser arranged in the cooling water passage through which cooling water of the internal combustion engine runs, exchanging heat between the working fluid evaporated by the evaporator and cooling water, and thereby condensing the working fluid, whereinthe evaporator and condenser are arranged in a closed loop channel through which the working fluid circulates,the evaporator and condenser are arranged to adjoin each other in the substantially horizontal direction,the evaporator has a plurality of evaporation side heat pipes arranged in parallel and is provided with a first communicating part communicating with first ends of the plurality of evaporation side heat pipes and a second communicating part communicating with the other ends, and,when mounted in a vehicle in the horizontal state, the second communicating part arranged at the bottom among the two communicating parts is positioned with the side far from the condenser lower than the side near it.

2. An exhaust heat recovery device as set forth in claim 1, further provided with: an evaporation side connecting part guiding said working fluid evaporated by said evaporator to said condenser anda condensation side connecting part guiding said working fluid condensed at said condenser to said evaporator,when mounted in a vehicle in the horizontal state, said condensation side connecting part being positioned with the side far from said condenser lower than the side close to said condenser.

3. An exhaust heat recovery device carried in a vehicle using an internal combustion engine as a drive source for operation and provided with an evaporator arranged in an exhaust gas passage through which exhaust gas exhausted from the internal combustion engine runs, exchanging heat between the exhaust gas and an evaporable and condensable working fluid sealed inside it, and thereby evaporating the working fluid,a condenser arranged in the cooling water passage through which cooling water of the internal combustion engine runs, exchanging heat between the working fluid evaporated by the evaporator and cooling water, and thereby condensing the working fluid,an evaporation side connecting part guiding said working fluid evaporated at said evaporator to said condenser, anda condensation side connecting part guiding said working fluid condensed at said condenser to said evaporator,when mounted in a vehicle in the horizontal state, the condensation side connecting part being positioned with the side far from said condenser below the side close to said condenser.

4. An exhaust heat recovery device as set forth in claim 1, wherein when mounted in a vehicle in the horizontal state, the bottom ends of said evaporation side heat pipes at the side far from said condenser among the plurality of evaporation side heat pipes are positioned lower than the bottom ends of said evaporation side heat pipes at the close side.

5. An exhaust heat recovery device as set forth in claim 1, further provided with a valve mechanism provided at a downstream side in said condenser and switching the channel through which the condensed working fluid flows into said evaporator.