JP2007332857A - Exhaust heat recovery equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide exhaust heat recovery equipment with a simplified structure capable of relieving thermal stress. <P>SOLUTION: The exhaust heat recovery equipment includes an evaporation section 1 disposed in a first casing 100 through which exhaust gas discharged from an engine flows so as to exchange heat between the exhaust gas and a working fluid filled in the evaporation section 1, and a condensation section 2 disposed in a second casing 200 through which cooling water of the engine flows so as to exchange heat between the working fluid and the cooling water. The first casing 100 and the second casing 200 are arranged adjacently to each other. The evaporation section 1 and the condensation section 2 are connected to each other in a communicatable manner so that the working fluid circulates through the evaporation section 1 and the condensation section 2. Heat transfer fins 8 that partially make contact with the first casing 100 and the second casing 200 are provided between the two casings 100 and 200. As a result, heat can be transferred between the first casing 100 and the second casing 200 via the heat transfer fins 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery device used for a vehicle such as an automobile.

  2. Description of the Related Art In recent years, a technology is known in which exhaust heat of exhaust gas is recovered from an exhaust system of a vehicle engine using the principle of a heat pipe, and this exhaust heat is used for promoting warm-up.

  In such an exhaust heat recovery device, a heat pipe evaporating part is arranged in the exhaust pipe of the engine, and a heat pipe condensing part is arranged in the engine cooling water path so that the cooling water is cooled by the exhaust heat of the exhaust gas. Is heated (see, for example, Patent Document 1).

Further, as a heat exchanger using the heat pipe principle, a loop heat pipe type heat exchanger has been proposed (see, for example, Patent Document 2). This includes a closed circulation path that forms a closed loop, a working fluid enclosed in the circulation path that can be evaporated and condensed, and an evaporation unit that is disposed in the circulation path and evaporates the working fluid by heat input from the outside. And a condensing part that is disposed at a position higher than the evaporation part of the circulation path and exchanges heat between the working fluid evaporated in the evaporation part and the heat transfer fluid from the outside.
Japanese Patent Laid-Open No. 62-268722 JP-A-4-45393

  In order to provide an exhaust heat recovery device having a simple and compact structure that is advantageous for mounting on a vehicle, it is desirable that the evaporation unit and the condensing unit are configured integrally. As an example, as shown in FIG. 6, the evaporation section J1 and the condensation section J2 that are heat exchange sections are disposed adjacent to each other in the horizontal direction, and both ends in the vertical direction of the heat pipe J3 of the evaporation section J1 and the condensation section J2. A configuration having a header (communication portion) J5 for communicating with each other is conceivable.

  However, in such an exhaust heat recovery device, there is a temperature difference between an evaporation section that tends to be hot because exhaust gas flows and a condensation section that tends to be relatively cold because engine coolant flows. Therefore, there is a problem that thermal stress is generated in the connecting portion that connects the evaporation portion and the condensing portion due to a difference in thermal expansion.

  By the way, the exhaust heat recovery device can raise the cooling water temperature at an early stage by recovering the exhaust heat at the start of winter, for example, so that the fuel consumption and the heating performance can be improved. On the other hand, when the engine is heavily loaded in summer, it is necessary to stop the recovery of exhaust heat in order to avoid overheating. For this reason, it is desirable to provide the exhaust heat recovery device with a valve mechanism that stops the circulation of the working fluid.

  In the exhaust heat recovery device having such a valve mechanism, when the valve mechanism is closed and the reflux of the working fluid is stopped, the working fluid is stored in the condensing unit and exhaust heat recovery is not performed. It becomes as much as the gas temperature (300 to 800 ° C.). For this reason, since a large temperature difference arises in an evaporation part and a condensation part (110 degrees C or less), a big thermal stress arises in the connection part which connects an evaporation part and a condensation part by a thermal expansion difference. Therefore, particularly in an exhaust heat recovery device having a valve mechanism, thermal stress based on the temperature difference between the evaporation section and the condensation section becomes a serious problem.

  On the other hand, it is conceivable to use an elastically deformable member such as a bellows for the connecting part that connects the evaporation part and the condensing part. However, the structure becomes complicated and the manufacturing cost increases. There is.

  In view of the above points, an object of the present invention is to provide an exhaust heat recovery device that can relieve thermal stress with a simple structure.

  In order to achieve the above object, according to the present invention, heat is exchanged between the exhaust gas and the working fluid enclosed in the first casing (100) through which the exhaust gas discharged from the engine flows. The first heat exchanging part (1) for performing the heat and the second heat (200) disposed in the second casing (200) through which the engine coolant flows, and exchanging heat between the working fluid and the coolant. The first casing (100) and the second casing (200) are arranged so as to be adjacent to each other, and the first heat exchanging section (1) and the second casing (2) are provided. The heat exchanging part (2) is connected in a communicating state, and is configured such that the working fluid circulates through the first heat exchanging part (1) and the second heat exchanging part (2). Between the (100) and the second casing (200), there is a heat transfer member (8) that partially contacts each of the two casings (100, 200). It is, and the first feature that it is the first casing via the heat transfer member (8) and (100) and second housing (200) are heat transferable.

  As a result, between the first casing (100) that tends to become high temperature because exhaust gas flows and the second casing (200) that tends to become relatively low temperature because cooling water of the engine flows. The temperature difference can be reduced. For this reason, it can suppress that a big thermal stress arises in a connection part (6) by a thermal expansion difference. At this time, since it is not necessary to make the connecting portion (6) an elastic structure such as a bellows, it is possible to relieve thermal stress with a simple structure.

  Moreover, in this invention, the heat-transfer member (8) is divided | segmented into plurality in the arrangement direction of the 1st housing | casing (100) and the 2nd housing | casing (200), and divided | segmented heat-transfer member (8) ) Between the adjacent heat transfer members (8) and the heat transfer relay member (80) capable of transferring heat is a second feature.

  Thereby, since the temperature distribution can be made uniform on the plate surface of the heat transfer relay member (80), heat transfer between the first casing (100) and the second casing (200) can be performed in two ways. It becomes possible to make uniform in the whole surface orthogonal to the arrangement direction of the housings (100, 200).

  Further, if the temperature difference between the first casing (100) and the second casing (200) is too large, the temperature difference between the two casings (100, 200) in one heat transfer member (8). May not be absorbed. At this time, a large temperature difference can be absorbed by dividing the heat transfer member (8) into multiple stages.

  In the first and second features, the working fluid is a fluid that can be evaporated and condensed, and heat exchange is performed between the exhaust gas and the working fluid enclosed therein in the first heat exchange section. The evaporation section (1) for evaporating the working fluid is provided, and the second heat exchange section performs heat exchange between the working fluid evaporated in the evaporation section (1) and the cooling water to condense the working fluid. (2) is provided, and the working fluid evaporated in the evaporator (1) and flowing out to the condenser (2) is condensed in the condenser (2) and returned to the evaporator (1). Also good.

  Further, the evaporation part (1) is provided with an evaporation side heat pipe (3a), the condensation part (2) is provided with a condensation side heat pipe (3b), and the evaporation side heat pipe (3a) is connected to the condensation side heat pipe (3b). A first connection part (61) through which the flowing working fluid passes, a second connection part (62) through which the working fluid flowing from the condensation side heat pipe (3b) to the evaporation side heat pipe (3a) passes, and a condensation side A reflux control means (7) for controlling the flow of the working fluid from the heat pipe (3b) to the evaporation side heat pipe (3a) may be provided.

  At this time, when the recirculation of the working fluid is stopped by the recirculation control means (7), the temperature of the evaporation section (1) becomes as high as the exhaust gas temperature, which is large in the evaporation section (1) and the condensing section (2). This is particularly effective because of the temperature difference.

  Also, a heat pipe (3c) in which the working fluid is enclosed is provided, and the heat pipe (3c) is disposed so as to straddle the first casing (100) and the second casing (200), One end side in the longitudinal direction of the heat pipe (3c) may be configured as the evaporation section (1), and the other end side may be configured as the condensation section (2).

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. The exhaust heat recovery device of the present embodiment recovers exhaust heat of exhaust gas from an exhaust system of a vehicle engine and uses this exhaust heat for promoting warm-up.

  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 includes an evaporation unit 1 and a condensing unit 2.

  The evaporation unit 1 is provided in a first housing 100 that is disposed in an exhaust pipe of an engine (not shown). Further, the evaporating unit 1 performs heat exchange between the exhaust gas and a working fluid described later to evaporate the working fluid.

  The condensing unit 2 is provided outside the exhaust pipe, and is provided in a second casing 200 that is disposed in a cooling water path of an engine (not shown). Further, the condensing unit 2 performs heat exchange between the heat transfer fluid evaporated in the evaporating unit 1 and the engine coolant to condense the working fluid. The second casing 200 is provided with a cooling water inlet 201 connected to the cooling water outlet side of the engine and a cooling water outlet 202 connected to the cooling water inlet side of the engine.

  The first casing 100 and the second casing 200 are arranged so as to be adjacent to each other. A clearance is provided between the first casing 100 and the second casing 200.

  Next, the configuration of the evaporation unit 1 will be described.

  The evaporation unit 1 includes a plurality of evaporation side heat pipes 3a and corrugated fins 4a joined to the outer surface of the evaporation side heat pipe 3a. The evaporation side heat pipes 3a are formed in a flat shape so that the exhaust gas flow direction (perpendicular to the plane of the drawing) coincides with the major axis direction, and a plurality of the evaporative heat pipes 3a are arranged in parallel so that the longitudinal direction thereof coincides with the vertical direction. Has been.

  In the evaporating unit 1, evaporating side heat pipes 3a are provided with evaporating side headers 5a that extend in the evaporating side heat pipe 3a stacking direction and communicate with all of the evaporating side heat pipes 3a at both ends in the longitudinal direction. Of the two evaporation side headers 5a, the evaporation side header 5a disposed on the upper end side in the vertical direction of the exhaust heat recovery unit is referred to as a first evaporation side header 51a, and the evaporation side header 5a disposed on the lower end side in the vertical direction. This is referred to as a second evaporation side header 52a.

  Next, the configuration of the condensing unit 2 will be described.

  The condensing unit 2 has a plurality of condensing side heat pipes 3b. Condensation-side heat pipes 3b are formed in a flat shape so that the flow direction (perpendicular to the plane of the drawing) of the engine cooling water coincides with the major axis direction, and a plurality of the condensing side heat pipes 3b are arranged in parallel so that the longitudinal direction thereof coincides with the vertical direction. Has been placed.

  In the condensing unit 2, condensing side heat pipes 3b are provided with condensing side headers 5b that extend in the stacking direction of the condensing side heat pipes 3b and communicate with all the condensing side heat pipes 3b at both ends in the longitudinal direction. Of the two condensing side headers 5b, the condensing side header 5b disposed on the upper end side in the vertical direction of the exhaust heat recovery device is referred to as a first condensing side header 51b, and the condensing side header 5b disposed on the lower end side in the vertical direction. This is referred to as a second condensing side header 52b.

  The evaporating side header 5a and the condensing side header 5b are connected in a communicating state via a cylindrical connecting portion 6. A closed loop is formed by the evaporation side, the condensation side heat pipes 3a and 3b, the evaporation side, the condensation side headers 5a and 5b, and the connecting portion 6, and a working fluid capable of evaporating and condensing water, alcohol, etc. Is enclosed. Here, of the two connecting portions 6, the one that is disposed on the upper side in the vertical direction and connects the first evaporation side header 51 a and the first condensing side header 51 b is a steam side connecting portion (first connecting portion). ) 61, which is arranged on the lower side in the vertical direction and connects the second evaporation side header 52 a and the second condensing side header 52 b is referred to as a reflux side connection portion (second connection portion) 62.

  A valve mechanism 7 is disposed in the second reflux side header 62b. The valve mechanism 7 forms a flow path that connects the condensation side heat pipe 3b and the reflux side connecting portion 62, and opens and closes the flow path according to the internal pressure of the evaporation side heat pipe 3a (pressure of the working fluid). It is an expression opening and closing means. Specifically, the valve mechanism 7 is closed when the internal pressure rises at a predetermined cooling water temperature from a normal valve opening state and exceeds the first predetermined pressure, and conversely, the internal pressure decreases and the first pressure decreases. When the pressure falls below a second predetermined pressure lower than the predetermined pressure, the valve is opened again. The valve mechanism 7 corresponds to the reflux control means of the present invention.

  In addition, heat transfer fins (heat transfer members) 8 that partially contact the two casings 100 and 200 are provided between the first casing 100 and the second casing 200. The heat transfer fin 8 is formed to have a plate-like flat plate portion 8a and a top portion 8b that positions the adjacent flat plate portions 8a at a predetermined distance apart. Between the flat plate portion 8a and the top portion 8b, a bent portion having a substantially right angle is provided. The top 8b is joined to the casings 100 and 200. For this reason, the heat transfer fins 8 are partially joined to the two cases 100 and 200, and the two cases 100 and 200 can transfer heat via the heat transfer fins 8.

  As described above, by providing the heat transfer fins 8 that are partially joined to the two casings 100 and 200 between the first casing 100 and the second casing 200, the exhaust gas flows. Therefore, the temperature difference between the first casing 100 that tends to become high temperature and the second casing 200 that tends to become relatively low temperature because the coolant of the engine flows can be reduced. For this reason, it can suppress that a big thermal stress arises in the connection part 6 by a thermal expansion difference. At this time, since it is not necessary to make the connecting portion 6 an elastic structure such as a bellows, it is possible to relax the thermal stress with a simple structure.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 2 is a cross-sectional view showing an exhaust heat recovery device according to the second embodiment. As shown in FIG. 2, in this embodiment, two heat transfer fins 8 are provided in the arrangement direction of the first casing 100 and the second casing 200 (in this embodiment, the heat pipes 3a and 3b are stacked). It is divided into Here, of the two divided heat transfer fins 8, the one disposed on the evaporation unit 1 side is referred to as a first heat transfer fin 81, and the one disposed on the condensation unit 2 side is the second heat transfer fin 8. This is referred to as a heat transfer fin 82.

  FIG. 3 is an enlarged view of a main part of FIG. As shown in FIG. 3, the two heat transfer fins 81 and 82 are formed to have plate-like flat plate portions 81a and 82a and top portions 81b and 82b that position adjacent flat plate portions 81a and 82a at a predetermined distance, respectively. ing. Further, between the flat plate portions 81a and 82a and the top portions 81b and 82b, bent portions having substantially right angles are respectively provided.

  A plate-shaped heat transfer plate (heat transfer relay member) 80 is disposed between the first heat transfer fins 81 and the second heat transfer fins 82. The heat transfer plate 80 is joined to the top portions 81 b and 82 b of the two heat transfer fins 81 and 82. That is, the heat transfer plate 80 is partially joined to the two heat transfer fins 81 and 82 so as to be able to transfer heat to the two heat transfer fins 81 and 82.

  The fin pitches of the two heat transfer fins 81 and 82 are different from each other. That is, the joining rates of the two heat transfer fins 81 and 82 with the heat transfer plate 80 are different. The fin pitch refers to the distance between the adjacent top portions 81b and 82b of the heat transfer fins 81 and 82.

  Thereby, since the temperature distribution can be made uniform on the plate surface of the heat transfer plate 80, heat transfer between the first casing 100 and the second casing 200 can be performed by arranging the two casings 100 and 200. It is possible to make uniform across the entire surface perpendicular to the direction (in the present embodiment, the surface perpendicular to the heat pipe 3a, 3b stacking direction).

  Further, by dividing the heat transfer fin 8 into two, even if the temperature difference between the first casing 100 and the second casing 200 is so large that the single heat transfer fin 8 cannot absorb the two casings, Since the temperature difference between the bodies 100 and 200 can be absorbed, thermal stress can be relaxed.

  Further, the amount of heat transfer can be adjusted by changing the number of divided stages of the heat transfer fins 8 and the fin pitch of the divided heat transfer fins 8, that is, the joining ratio between the heat transfer fins 8 and the heat transfer plate 80. Can do.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 4 is a cross-sectional view showing an exhaust heat recovery device according to the third embodiment. As shown in FIG. 4, in this embodiment, it has the hollow rod-shaped heat pipe 3c arrange | positioned in parallel so that a longitudinal direction may correspond with a perpendicular direction. Plate fins 4c are joined to the outer surface of the heat pipe 3c. The lower part in the vertical direction of the heat pipe 3c is disposed in the first housing 100 through which the exhaust gas discharged from the engine flows, and constitutes the evaporation unit 1. Further, the upper part in the vertical direction of the heat pipe 3 c is disposed in the second casing 200 through which the cooling water flows, and constitutes the condensing unit 2.

  In addition, heat transfer fins (heat transfer members) 8 that partially contact the two casings 100 and 200 are provided between the first casing 100 and the second casing 200. The heat transfer fin 8 is formed to have a plate-like flat plate portion 8a and a top portion 8b that positions the adjacent flat plate portions 8a at a predetermined distance apart. Between the flat plate portion 8a and the top portion 8b, a bent portion having a substantially right angle is provided. The top 8b is joined to the casings 100 and 200. For this reason, the heat transfer fins 8 are partially joined to the two cases 100 and 200, and the two cases 100 and 200 can transfer heat via the heat transfer fins 8.

  In the heat pipe 3c as in the present embodiment, the flow directions of the working fluid vapor and the liquid working fluid are always opposite to each other, so that interference occurs between them. When the temperature difference between the evaporation unit 1 and the condensing unit 2 increases, the flow rates of the working fluid vapor and the liquid working fluid both increase, so that the liquid working fluid is blown up and scattered by the vapor flow. As a result, the working fluid flowing back to the condensing unit 2 decreases, and finally it is dried out. At this time, since the evaporation unit 1 is only heated by the heat of the exhaust gas, the temperature of the evaporation unit 1 rises to the same level as the exhaust gas. And a great temperature difference arises in an evaporation part and a condensation part, and a big thermal stress arises in the connection part which connects an evaporation part and a condensation part by a thermal expansion difference.

  On the other hand, by providing the heat transfer fins 8 partially joined to the two casings 100 and 200 between the first casing 100 and the second casing 200 as in the present embodiment. The temperature difference between the first casing 100 and the second casing 200 can be reduced. For this reason, it can suppress that a big thermal stress arises in the connection part 6 by a thermal expansion difference. At this time, since it is not necessary to make the connecting portion 6 an elastic structure such as a bellows, it is possible to relax the thermal stress with a simple structure.

(Other embodiments)
In addition, in each said embodiment, although the heat pipe system is used, it is not restricted to this, For example, you may use the system which circulates a refrigerant | coolant as shown in FIG. Specifically, the heat absorption part (first heat exchanging part) 10 disposed in the first housing 100 through which the exhaust gas flows and the second housing 200 through which cooling water flows are disposed. The heat dissipating part (second heat exchanging part) 20 may be disposed in the closed loop flow path, and the refrigerant (for example, silicon oil) may be circulated in the closed loop flow path by the pump 50. At this time, the heat absorption part 10 and the heat radiation part 20 have tubes 3d and 3e through which the refrigerant passes, respectively.

  Moreover, in each said embodiment, while having the top part 8b which positions the plate-shaped flat plate part 8a (81a, 82a) and the adjacent flat plate part 8a (81a, 82a) a predetermined distance apart as a heat-transfer member, flat plate part 8a (81a, 82a) and the top 8b (81b, 82b) are used heat transfer fins 8 (81, 82) provided with a substantially right-angled bent portion, but not limited to this, wavy corrugated fins It may be used. In addition, the heat transfer member may have any shape as long as it has a shape that can be thermally contacted with the two casings 100 and 200, such as a rod shape whose both ends are joined to the two casings 100 and 200, respectively. be able to.

  Moreover, in the said 2nd Embodiment, although the heat-transfer fin 2 was divided | segmented into two, you may divide | segment not only to this but to three or more.

  In the second embodiment, the fin pitch of the first heat transfer fins 81 is larger than that of the second heat transfer fins 82. However, the present invention is not limited to this and may be the same as the second heat transfer fins 82. However, it may be smaller than the second heat transfer fins 81.

It is sectional drawing which shows the exhaust heat recovery device which concerns on 1st Embodiment. It is sectional drawing which shows the exhaust heat recovery device which concerns on 2nd Embodiment. It is a principal part enlarged view of FIG. It is sectional drawing which shows the exhaust heat recovery device which concerns on 2nd Embodiment. It is sectional drawing which shows the exhaust heat recovery device which concerns on other embodiment. It is sectional drawing which shows the conventional exhaust heat recovery device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Evaporation part (1st heat exchange part), 2 ... Condensing part (2nd heat exchange part), 3a-3c ... Heat pipe, 7 ... Valve mechanism (reflux control means), 8 ... Heat transfer fin (Transfer) Heat member), 61... Steam side connecting portion (first connecting portion), 62 .. reflux side connecting portion (second connecting portion), 80... Heat transfer plate (heat transfer relay member), 100. Body, 200 ... second housing.

Claims (5)

A first heat exchanging portion (1) that is arranged in a first casing (100) through which exhaust gas discharged from the engine flows and exchanges heat between the exhaust gas and the working fluid sealed inside. )When,
A second heat exchanging part (2) arranged in a second casing (200) through which the cooling water of the engine flows and exchanging heat between the working fluid and the cooling water;
The first casing (100) and the second casing (200) are disposed adjacent to each other,
The first heat exchange part (1) and the second heat exchange part (2) are connected in communication, and the working fluid is connected to the first heat exchange part (1) and the second heat exchange part. (2) is configured to circulate,
Between the first casing (100) and the second casing (200), there is a heat transfer member (8) that partially contacts each of the two casings (100, 200). Exhaust heat characterized in that heat transfer is possible between the first casing (100) and the second casing (200) via the heat transfer member (8). Collector. The heat transfer member (8) is divided into a plurality in the arrangement direction of the first casing (100) and the second casing (200),
Between the divided heat transfer members (8), the heat transfer relay member (80) capable of transferring heat with the adjacent heat transfer member (8) includes the first casing (100) and the second heat transfer member (8). 2. The exhaust heat recovery device according to claim 1, wherein the exhaust heat recovery device is disposed to correspond to mutually facing portions of the casing (200). The working fluid is a fluid that can be evaporated and condensed;
The first heat exchanging unit includes an evaporation unit (1) for exchanging heat between the exhaust gas and the working fluid enclosed therein, and evaporating the working fluid.
The second heat exchanging unit has a condensing unit (2) for exchanging heat between the working fluid evaporated in the evaporating unit (1) and the cooling water to condense the working fluid. ,
The working fluid evaporated by the evaporation section (1) and flowing out to the condensation section (2) is condensed by the condensation section (2) and recirculated to the evaporation section (1). The exhaust heat recovery device according to claim 1 or 2. The evaporation section (1) has an evaporation side heat pipe (3a), the condensation section (2) has a condensation side heat pipe (3b),
A first connecting portion (61) through which the working fluid flowing from the evaporation side heat pipe (3a) to the condensation side heat pipe (3b) passes;
A second connecting portion (62) through which the working fluid flowing from the condensation side heat pipe (3b) to the evaporation side heat pipe (3a) passes;
The exhaust heat recovery according to claim 3, further comprising a reflux control means (7) for controlling a flow of the working fluid from the condensation side heat pipe (3b) to the evaporation side heat pipe (3a). vessel. A heat pipe (3c) in which the working fluid is sealed;
The heat pipe (3c) is disposed so as to straddle the first casing (100) and the second casing (200),
The exhaust heat according to claim 3, wherein one end side in the longitudinal direction of the heat pipe (3c) is configured as the evaporation section (1) and the other end side is configured as the condensing section (2). Collector.

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