JP4779922B2 - Exhaust heat recovery unit - Google Patents

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).

In addition, a loop heat pipe type heat exchanger has been proposed as a heat exchanger using the principle of a heat pipe (see, for example, Patent Document 2). This is a closed circulation path that forms a closed loop, a heat transfer fluid that is enclosed in the circulation path and can be evaporated and condensed, and an evaporation 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 heat transfer 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. 5, the evaporator J1 and the condenser J2 are disposed adjacent to each other in the horizontal direction, and the headers that respectively communicate the vertical ends of the heat pipe J3 of the evaporator J1 and the condenser J2 with each other. (Communication part) The structure which has J5 can be considered.

  In the exhaust heat recovery device, the working fluid evaporated in the evaporation portion J1 flows into the condensing portion J2 through the upper header J5, and the working fluid is condensed into a liquid in the condensing portion J2, and the lower header J5 is removed. And flows into the evaporation section J1. Due to the balance between the evaporation of the working fluid in the evaporation section J1 and the condensation of the working fluid in the condensation section J2, a water level difference (water head difference h) of the working fluid (liquid) occurs between the evaporation section J1 and the condensation section J2. . Due to the water head difference h, the working fluid is recirculated from the condensing unit J2 to the evaporation unit J1, thereby circulating the working fluid. Therefore, in order to return a sufficient amount of working fluid from the condensing part J2 to the evaporation part J1, it is necessary to ensure the water head difference h.

  By the way, in the exhaust heat recovery device, heat exchange between the working fluid evaporated in the evaporation section J1 and the engine cooling water is performed on the upstream side of the condensing section J2. Therefore, in order to ensure the heat exchange performance of the condensing part J2, it is necessary to ensure the heat dissipation performance above the heat pipe J3 arranged in the condensing part J2 (the side into which the working fluid evaporated in the evaporating part J1 flows). There is.

  In view of the above points, the present invention secures a water head difference between the evaporation unit and the condensation unit during circulation of the working fluid, and exhaust heat capable of ensuring the heat radiation performance on the upper side of the heat pipe disposed in the condensation unit. The purpose is to provide a collector.

  In order to achieve the above object, according to the present invention, there is provided an exhaust heat recovery device mounted on a vehicle having an internal combustion engine as a driving source for travel, and disposed in an exhaust gas path through which exhaust gas discharged from the internal combustion engine flows. And an evaporating section (1) for exchanging heat between the exhaust gas and the working fluid that can be evaporated and condensed enclosed therein, and evaporating the working fluid, and in the cooling water path through which the cooling water of the internal combustion engine flows And a condensing part (2) for exchanging heat between the working fluid evaporated in the evaporating part (1) and the cooling water to condense the working fluid, and comprising the evaporating part (1) and the condensing part (2 ) Is disposed in a closed loop flow path through which the working fluid circulates, and the evaporator (1) and the condenser (2) are disposed so as to be adjacent to each other in the substantially horizontal direction, and the condenser (2). Has a plurality of condensing side heat pipes (3b) arranged in parallel The condensation side heat pipe (3b) has a small cross-sectional area (300) having a smaller cross-sectional area than its upper end, and the small cross-sectional area (300) is in the condensation side heat pipe (3b). It is characterized by being arranged below the upper surface of the working fluid when the evaporation section (1) is heated.

  When the circulation of the working fluid is started from the state where the circulation of the working fluid is stopped (the evaporation portion (1) is not heated), and the circulation of the working fluid is started, the condensation side heat pipe (3b) The position of the upper surface (water surface) of the working fluid rises. At this time, in the condensing side heat pipe (3b), the small cross-sectional area part (300) having a smaller cross-sectional area (area of the cross section perpendicular to the longitudinal direction of the condensing side heat pipe (3b)) than the upper end part is evaporated. Position of the upper surface (water surface) of the working fluid in the condensation side heat pipe (3b) when the working fluid is circulated by disposing it below the upper surface (water surface) of the working fluid when the part (1) is heated Can be raised more. Thereby, the water head difference between an evaporation part (1) and a condensation part (2) can be enlarged.

  Further, in the condensation side heat pipe (3b), the small cross-sectional area part (300) is arranged below the upper surface (water surface) of the working fluid when the evaporation part (1) is heated. Therefore, it is not necessary to reduce the cross-sectional area of the portion above the upper surface (water surface) of the working fluid when the evaporation section (1) is heated in the condensation side heat pipe (3b). Thereby, the outer surface area of the upper side of a condensation side heat pipe (3b) can be enlarged, and heat dissipation performance can be improved.

  Therefore, it is possible to ensure the water head difference between the evaporation section (1) and the condensation section (2) during the working fluid circulation and to ensure the heat radiation performance on the upper side of the condensation side heat pipe (3b).

  Moreover, the valve mechanism (6) which opens and closes the flow path in which the condensed said working fluid flows into the said evaporation part (1) can be provided in the downstream in a condensation part (2).

  In this case, when the valve mechanism (6) is closed and the reflux of the working fluid is stopped, the working fluid is stored in the condensing unit (2). Therefore, a volume for storing the condensed working fluid is required on the upstream side of the valve mechanism (6) in the condensing unit (2). As in the above feature, in the condensation side heat pipe (3b), the small cross-sectional area part (300) is arranged below the upper surface (water surface) of the working fluid when the evaporation part (1) is heated. Thus, in the condensation side heat pipe (3b), it is possible to increase the cross-sectional area of the flow path above the upper surface (water surface) of the working fluid when the evaporation section (1) is heated. For this reason, it becomes possible to ensure the storage volume of the condensed working fluid on the upper side of the condensation side heat pipe (3b).

  Moreover, you may arrange | position a small cross-sectional area part (300) at least below the upper surface of the working fluid in the condensation side heat pipe (3b) when the evaporation part (1) is not heated.

  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 FIGS. 1 and 2. The exhaust heat recovery device of the present embodiment recovers exhaust heat of exhaust gas from an exhaust system of a vehicle engine (internal combustion 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 evaporator 1 and the condenser 2 are arranged so as to be adjacent in the horizontal direction.

  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 working fluid evaporated in the evaporating unit 1 and the engine cooling water 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.

  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 the evaporating side heat pipes 3a at both ends in the longitudinal direction of the evaporating side heat pipe 3a. Among the evaporation side headers 5a, the evaporation side header 5a disposed on the upper end side of the exhaust heat recovery device is referred to as a first evaporation side header 51a, and the evaporation side header 5a disposed on the lower end side 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 includes a plurality of condensing side heat pipes 3b and straight fins 4b joined to the outer surface of the condensing side heat pipe 3b. Condensation-side heat pipes 3b 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 condensing-side heat pipes 3b are arranged in parallel so that the longitudinal direction thereof coincides with the vertical direction. Has been.

  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. Among the 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. The condensation side header 52b.

  The evaporation side header 5a and the condensation side header 5b are connected in a communicating state. A closed loop is formed by the evaporation side and condensation side heat pipes 3a and 3b, and the evaporation side and condensation side headers 5a and 5b, and a working fluid capable of evaporating and condensing such as water and alcohol is enclosed therein. ing.

  The valve mechanism 6 is disposed in the second condensing side header 52b. The valve mechanism 6 forms a flow path connecting the condensation side heat pipe 3b and the second evaporation side header 52a, and opens and closes the flow path according to the internal pressure (pressure of the working fluid) of the evaporation side heat pipe 3a. It is a diaphragm type opening and closing means. Specifically, the valve mechanism 6 closes 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, When the pressure falls below a second predetermined pressure lower than the predetermined pressure, the valve is opened again. As a result, exhaust heat recovery can be stopped in order to avoid overheating, such as during high engine loads in summer.

  Next, a detailed configuration of the condensation side heat pipe 3b in the first embodiment will be described. In the present embodiment, the configurations of the plurality of condensing side heat pipes 3b are all the same.

  FIG. 2 is a perspective view showing the condensing side heat pipe 3b in the first embodiment. As shown in FIG. 2, the condensing side heat pipe 3b of the present embodiment includes an upper portion 31 disposed on the upper side (first condensing side header 51b side), and a lower side (second condensing side header 52b side). The lower portion 32 is disposed between the upper portion 31 and the lower portion 32, and the intermediate portion 33 is disposed between the upper portion 31 and the lower portion 32.

  The cross-sectional area of the lower part 32 in the condensation side heat pipe 3b (the area of the cross section perpendicular to the longitudinal direction of the condensation side heat pipe 3b) is smaller than the cross-sectional area of the upper part 31. Further, the intermediate portion 33 connects the upper portion 31 and the lower portion 32 so that the cross-sectional area gradually decreases from the lower end of the upper portion 31 toward the upper end of the lower portion 32. For this reason, the intermediate portion 33 has a smaller cross-sectional area than the upper portion 31 in all portions. Hereinafter, the lower portion 32 and the intermediate portion 33 are also referred to as a small cross-sectional area portion 300. In the present embodiment, the cross-sectional area is changed by changing only the length in the width direction of the condensation side heat pipe 3b.

  Further, the small cross-sectional area 300 is an upper surface of the working fluid in the condensation side heat pipe 3b when the evaporation unit 1 is heated, that is, when the working fluid is circulated (hereinafter referred to as a circulating water surface, FIG. 2). (See the middle broken line A). The water surface position during circulation varies depending on the size and operating conditions of the exhaust heat recovery device, but, for example, in a range where the upper surface of the working fluid in the condensation side heat pipe 3b can exist when the evaporation unit 1 is heated. It can be set at any position.

  Further, in the present embodiment, the lower portion 32 having a smaller cross-sectional area than the intermediate portion 33 operates in the condensation side heat pipe 3b when the evaporation portion 1 is not heated, that is, when the circulation of the working fluid is stopped. It arrange | positions below the upper surface of a fluid (henceforth the water surface at the time of a stop, please refer to the broken line B in FIG. 2). In addition, the water surface position at the time of a stop is determined by the quantity of the working fluid enclosed at the time of manufacture of an exhaust heat recovery device.

  When the circulation of the working fluid is started from the state where the circulation of the working fluid is stopped (the evaporation unit 1 is not heated), and the circulation of the working fluid is started, the upper surface of the working fluid in the condensation side heat pipe 3b (Water surface) position rises. At this time, as in the present embodiment, in the condensation side heat pipe 3b, the small cross-sectional area 300 having a smaller cross-sectional area than the upper part 31 is disposed below the circulating water surface, thereby condensing the working fluid during circulation. The upper surface (water surface) position of the working fluid in the side heat pipe 3b can be further raised. Thereby, the water head difference between the evaporation part 1 and the condensation part 2 can be enlarged.

  Further, in the condensation side heat pipe 3b, the small cross-sectional area 300 is disposed below the circulating water surface, so there is no need to reduce the cross-sectional area of the portion above the circulating water surface. Thereby, the outer surface area of the upper side of the condensation side heat pipe 3b can be enlarged, and heat dissipation performance can be improved.

  Therefore, it is possible to ensure the water head difference between the evaporation unit 1 and the condensing unit 2 when the working fluid is circulated, and to ensure the heat dissipation performance on the upper side of the condensing side heat pipe 3b.

  In the present embodiment, the valve mechanism 6 that controls the flow of the working fluid from the condensing unit 2 to the evaporating unit 1 is disposed in the second condensing side header 52b. In this case, when the valve mechanism 6 is closed and the reflux of the working fluid is stopped, the working fluid is stored in the condensing unit 2. Therefore, a volume for storing the condensed working fluid is required on the upstream side of the valve mechanism 6 in the condensing unit 2. As described above, by disposing the small cross-sectional area 300 in the condensation side heat pipe 3b below the circulating water surface, the flow path cross-sectional area of the portion above the circulating water surface in the condensation side heat pipe 3b can be reduced. Can be bigger. For this reason, it becomes possible to ensure the storage volume of the condensed working fluid in the upper part 31 of the condensation side heat pipe 3b.

(Second Embodiment)
Next, a second 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. 3 is an enlarged perspective view showing a main part of the condensing side heat pipe 3b. FIG. 3A shows a configuration of the second embodiment, and FIG. 3B shows a conventional configuration.

  As shown in FIG. 3A, the condensing part 2 of this embodiment is a so-called drone cup type, and is formed by stacking a plurality of tube plates in the middle and then joining them by brazing. Thus, a plurality of flat condensing side heat pipes 3b are formed and laminated, and condensing side headers 5b are formed at both ends in the longitudinal direction of the condensing side heat pipes 3b. In the present embodiment, the lower part 32 of the condensation side heat pipe 3b corresponds to the second condensation side header 52b. In addition, a valve mechanism 6 having a substantially cylindrical shape for controlling the flow of the working fluid from the condensing unit 2 to the evaporation unit 1 is disposed in the second condensing side header 52b.

  Conventionally, as shown in FIG. 3B, the portion below the valve mechanism J6 in the second condensing side head J52b (see the hatched portion X in FIG. 3B) is between the evaporation unit 1 and the condensing unit 2. It was a dead space that did not contribute to ensuring the head differential.

  On the other hand, in the second embodiment, the lower part 32 in the condensation side heat pipe 3b, that is, the sectional area of the second condensation side header 52b is made smaller than the sectional area of the upper part 31, thereby dead space (FIG. 3). The volume of (a) middle hatched portion Y) can be reduced. Thereby, the water head difference between the evaporation unit 1 and the condensation unit 2 can be increased, and the flow rate of the working fluid flowing into the evaporation unit 1 from the condensation unit 2 can be increased. For this reason, the circulation amount of a working fluid can be increased and heat recovery performance can be improved.

(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 an enlarged perspective view showing a main part of the condensation side heat pipe 3b according to the third embodiment. As shown in FIG. 4, the small cross-sectional area 300 of the present embodiment has a shape in which the working fluid flow path gradually decreases from the upper side to the lower side and then gradually increases. Thereby, the effect similar to the said 1st Embodiment can be acquired.

(Other embodiments)
In each of the above embodiments, the sectional area is changed by changing only the length in the width direction of the condensation side heat pipe 3b. However, the present invention is not limited to this, and for example, the length in the thickness direction of the condensation side heat pipe 3b. The cross-sectional area may be changed by changing the height.

  Moreover, in each said embodiment, although the small area part 300 was provided in all the some condensation side heat pipes 3b, it should just provide in at least 1 condensation side heat pipe 3b.

  Moreover, in each said embodiment, although the valve mechanism 6 was provided in the 2nd condensation part side header 52b, it does not need to provide.

It is sectional drawing which shows the exhaust heat recovery device which concerns on 1st Embodiment. It is an expansion perspective view which shows the principal part of the condensation side heat pipe 3b which concerns on 1st Embodiment. It is an expansion perspective view which shows the principal part of the condensation side heat pipe 3b, (a) shows the structure of this 2nd Embodiment, (b) has shown the conventional structure. It is an expansion perspective view which shows the principal part of the condensation side heat pipe 3b which concerns on 3rd Embodiment. It is sectional drawing which shows the conventional exhaust heat recovery device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Evaporation part, 2 ... Condensing part, 3b ... Condensation side heat pipe, 6 ... Valve mechanism, 300 ... Small cross-sectional area part.

Claims (3)

An exhaust heat recovery device mounted on a vehicle having an internal combustion engine as a driving source for traveling,
The exhaust gas discharged from the internal combustion engine is disposed in an exhaust gas path through which heat is exchanged between the exhaust gas and a working fluid that can be condensed and condensed, and the working fluid is evaporated. Evaporating section (1)
A condensing part that is arranged in a cooling water path through which the cooling water of the internal combustion engine flows and that exchanges heat between the working fluid evaporated in the evaporation part (1) and the cooling water to condense the working fluid. (2)
The evaporating part (1) and the condensing part (2) are arranged in a closed loop flow path through which the working fluid circulates,
The evaporating part (1) and the condensing part (2) are arranged so as to be adjacent in a substantially horizontal direction,
The condensing part (2) has a plurality of condensing side heat pipes (3b) arranged in parallel,
The condensation side heat pipe (3b) has a small cross-sectional area part (300) having a smaller cross-sectional area than its upper end part,
The small cross-sectional area part (300) is arranged below the upper surface of the working fluid when the evaporation part (1) is heated in the condensation side heat pipe (3b). Exhaust heat recovery device. The valve mechanism (6) provided on the downstream side in the condensing part (2) and opening and closing a flow path through which the condensed working fluid flows into the evaporation part (1) is provided. Exhaust heat recovery device. The small cross-sectional area part (300) is arranged at least below the upper surface of the working fluid when the evaporation part (1) is not heated in the condensation side heat pipe (3b). The exhaust heat recovery device according to claim 1 or 2.

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