JP2008202451A - Exhaust heat recovery apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery apparatus capable of inhibiting recovery of excessive heat with a simple structure. <P>SOLUTION: This device is provided with; an evaporation part 1 arranged in an exhaust gas path in which exhaust gas exhausted from an internal combustion engine, exchanging heat between exhaust gas and working fluid capable of evaporating and condensing filled inside, and evaporating working fluid; a condensation part 2 arranged in a cooling water path in which cooling water of the internal combustion engine flows, exchanging heat between working fluid evaporating in the evaporation part 1 and cooling water, and condensing working fluid; an evaporation side connection part 61 leading working fluid evaporating in the evaporation part 1 to the condensation part 2; and a condensation side connection part 62 introducing working fluid condensing in the condensation part 2 to the evaporation part 1. A fixed restriction 7 is provided at the evaporation side connection part 61. <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

  An example of the exhaust heat recovery unit as described above is shown in FIG. FIG. 5 is a cross-sectional view of the exhaust heat recovery device.

  In the exhaust heat recovery device shown in FIG. 5, the evaporation unit J1 and the condensing unit J2 which are heat exchange units are arranged adjacent to each other in the horizontal direction, and both ends in the vertical direction of the heat pipe J3 of the evaporating unit J1 and the condensing unit J2 A header (communication portion) J5 for communication is provided.

  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. As the valve mechanism, for example, a diaphragm type valve mechanism in which the valve body is driven by a diaphragm that is displaced according to the pressure of the working fluid can be considered. Thus, by providing a valve mechanism in the exhaust heat recovery device, it is possible to suppress recovery of an excessive amount of heat.

  However, when the above-described valve mechanism is provided in the exhaust heat recovery device, a diaphragm, a valve body, and the like are required, and the configuration becomes complicated, resulting in an increase in manufacturing cost.

  In view of the above points, an object of the present invention is to provide an exhaust heat recovery device that can suppress recovery of an excessive amount of heat with a simple configuration.

  In order to achieve the above object, according to the present invention, heat is generated between the exhaust gas and the working fluid that can be evaporated and condensed, which is disposed in the exhaust gas passage through which the exhaust gas discharged from the internal combustion engine flows. An evaporator (1) that exchanges and evaporates the working fluid and a cooling water path that is disposed in the cooling water passage through which the cooling water of the internal combustion engine flows and heats between the working fluid evaporated in the evaporating unit (1) and the cooling water. Condensation part (2) which performs exchange and condenses working fluid, evaporation side connection part (61) which leads working fluid evaporated in evaporation part (1) to condensation part (2), and condensation in condensation part (2) A condensing side connecting part (62) for guiding the working fluid to the evaporating part (1), and the evaporating side connecting part (61) is provided with a throttle mechanism (7, 7a to 7c). Yes.

  The working fluid evaporated in the evaporation section (1) has the maximum flow velocity when passing through the throttle mechanism (7, 7a to 7c). When the flow velocity of the working fluid when passing through the throttle mechanism (7, 7a to 7c) reaches the sonic velocity, the flow is blocked and the flow rate of the working fluid passing through the throttle mechanism (7, 7a to 7c) does not increase any more. . That is, when the flow velocity of the working fluid when passing through the throttle mechanism (7, 7a to 7c) becomes the sonic velocity, the flow rate of the working fluid passing through the throttle mechanism (7, 7a to 7c) becomes maximum, and the exhaust heat recovery device The amount of recovered heat is maximized.

  Therefore, the throttle opening degree of the throttle mechanism (7, 7a to 7c) is set in advance so that a desired maximum recovered heat amount can be obtained when the flow velocity of the working fluid when passing through the throttle mechanism (7, 7a to 7c) reaches the speed of sound. By setting, the upper limit of the recovered heat amount can be determined. At this time, since members constituting the valve mechanism such as a diaphragm can be abolished, it is possible to suppress recovery of an excessive amount of heat with a simple configuration.

  In the exhaust heat recovery device having the above characteristics, the throttle mechanism may be a fixed throttle (7). According to this, collection | recovery of excess heat quantity can be suppressed with a simpler structure.

  In the exhaust heat recovery device having the above characteristics, the throttle mechanism may be a variable throttle (7a to 7c) that changes the throttle opening according to the temperature of the cooling water or the temperature of the working fluid.

  According to this, when the temperature of the cooling water or the working fluid becomes high, the throttle opening of the throttle mechanism (7a to 7c) can be reduced to limit the amount of recovered heat. For this reason, since the amount of recovered heat can be limited at the time of high engine load in summer when the temperature of the cooling water and the working fluid is high, overheating can be avoided. On the other hand, at the start of the winter when the temperature of the cooling water and working fluid is low, the amount of recovered heat is not limited, so the temperature of the cooling water can be raised early, improving fuel economy and heating performance Can be made.

  In the exhaust heat recovery unit having the above characteristics, the variable throttles (7a to 7c) may be configured to reduce the throttle opening according to the temperature rise of the cooling water or the temperature of the working fluid.

  According to this, since the throttle opening of the throttle mechanism (7a-7c) becomes small at the time of high engine load in summer when the temperature of the cooling water and the working fluid is high, the amount of recovered heat can be limited. . Thereby, overheating can be avoided. On the other hand, at the start of the winter when the temperature of the cooling water and the working fluid is low, the throttle opening of the throttle mechanism (7a to 7c) becomes large, so that the amount of recovered heat is not limited. Thereby, since a cooling water temperature can be raised early, a fuel consumption and heating performance can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim 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 this 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 evaporation unit 1 is provided in a first housing 100 that is disposed in an exhaust gas path (in this embodiment, 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.

  In the present embodiment, the first casing 100 and the second casing 200 are disposed 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 evaporation side 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 evaporation section 1, evaporation side headers 5a extending in the stacking direction of the evaporation side heat pipe 3a and communicating with all the evaporation side heat pipes 3a are provided at both ends in the longitudinal direction of the evaporation side heat pipe 3a. Of the two 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. It is called 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 condensing side corrugated fins 4b joined to the outer surface of the condensing side heat pipe 3b. The condensation side heat pipe 3b is formed in a flat shape so that the exhaust gas flow direction (perpendicular to the plane of the drawing) in the evaporation section 1 coincides with the major axis direction, and a plurality of the condensing side heat pipes 3b coincide with the vertical direction. These are arranged in parallel.

  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 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 is referred to as a second condensing side header. It is called the 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. As a result, the working fluid circulates through the evaporator 1 and the condenser 2.

  Here, it arrange | positions among two connection parts 6 above, connects the 1st evaporation side header 51a and the 1st condensation side header 51b, and the working fluid evaporated in the evaporation part 1 is made into the condensation part 2. What is guided is referred to as an evaporation side connecting portion 61. Moreover, it arrange | positions in the downward side among the two connection parts 6, connects the 2nd evaporation side header 52a and the 2nd condensation side header 52b, and makes the working fluid condensed by the condensation part 2 to the evaporation part 1. What is guided is referred to as a condensing side connecting portion 62.

  A fixed throttle 7 is provided in the evaporation side connecting portion 61. In the present embodiment, the fixed diaphragm 7 is formed on the diaphragm member 70, and the diaphragm member 70 is inserted into the evaporation side connecting portion 61.

  The throttle member 70 is formed in a shape that gradually reduces the cross-sectional area of the flow path through which the working fluid evaporated in the evaporation unit 1 passes and then gradually increases the cross-sectional area. That is, the throttle member 70 is continuously formed on the first tapered surface 701 having a diameter reduced from the upstream side to the downstream side of the working fluid flow, and on the downstream side of the working fluid flow of the first tapered surface 701, and the working fluid And a second tapered surface 702 having an enlarged diameter from the upstream side to the downstream side.

  In the present embodiment, the working fluid evaporated in the evaporation unit 1 has the maximum flow velocity when passing through the fixed throttle 7. When the flow velocity of the working fluid when passing through the fixed restrictor 7 reaches the sonic velocity, the flow is blocked and the flow rate of the working fluid passing through the fixed restrictor 7 does not increase any more. That is, when the flow velocity of the working fluid when passing through the fixed throttle 7 becomes the sonic velocity, the flow rate of the working fluid passing through the fixed throttle 7 is maximized, and the amount of heat recovered by the exhaust heat recovery device is maximized.

  Therefore, the upper limit of the recovered heat quantity is determined by setting the throttle opening of the fixed throttle 7 in advance so that the desired maximum recovered heat quantity can be obtained when the flow velocity of the working fluid when passing through the fixed throttle 7 reaches the sonic speed. be able to. At this time, since members constituting the valve mechanism such as a diaphragm and a valve body can be eliminated, it is possible to suppress recovery of an excessive amount of heat with a simple configuration.

(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. 2 is an enlarged cross-sectional view showing the steam side connecting portion 61 of the exhaust heat recovery device according to the second embodiment, where (a) shows the working fluid at a high temperature and (b) shows the working fluid at a low temperature.

  As shown in FIGS. 2A and 2B, a variable throttle 7 a that changes the throttle opening according to the temperature of the working fluid is disposed in the evaporation side connecting portion 61. The variable throttle 7a is configured to reduce the throttle opening according to the temperature rise of the working fluid, that is, to reduce the passage cross-sectional area of the passage through which the working fluid flows.

  In the present embodiment, the variable diaphragm 7a is made of a material that can be deformed by the ambient temperature. As a material of the variable aperture 7a, for example, a bimetal or a shape memory alloy can be used. Note that, in this embodiment, the passage through which the working fluid flows is not completely blocked even when the temperature of the working fluid in the evaporation side connecting portion 61 rises.

  In the present embodiment, when the temperature of the working fluid becomes high, the throttle opening of the variable throttle 7a becomes small, so that the amount of recovered heat is limited. For this reason, since the amount of recovered heat can be limited when the temperature of the working fluid is high in the summer when the engine is heavily loaded, overheating can be avoided.

  On the other hand, when the temperature of the working fluid becomes low, the throttle opening of the variable throttle 7a is increased, so that the amount of recovered heat is not limited. For this reason, the coolant temperature can be raised at an early stage, for example, at the start of winter when the temperature of the working fluid is low, and fuel consumption and heating 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 second embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 3 is an enlarged cross-sectional view showing the steam side connecting portion 61 of the exhaust heat recovery device according to the third embodiment. As shown in FIG. 3, the variable throttle 7 b of the present embodiment has one end on a throttle hole 71, a valve body 72 that opens and closes the throttle hole 71, and a face on the opposite side of the face facing the throttle hole 71 in the valve body 72. Has a temperature-sensitive deformation member 73 fixed thereto.

  The other end of the temperature-sensitive deformation member 73 is fixed to a support member 74 provided in the evaporation side connecting portion 61. The temperature-sensitive deformation member 73 is made of, for example, a thermometal made of a metal having a higher thermal expansion coefficient than that of the metal constituting the steam side connecting portion 61, thermowax, or the like. When the temperature of the working fluid reaches a predetermined temperature or more, it expands thermally.

  Therefore, when the temperature of the working fluid in the evaporation side connecting portion 61 rises, the valve body 72 moves in a direction to reduce the opening degree of the throttle hole 71. On the other hand, when the temperature of the working fluid in the evaporation side connecting portion 61 decreases, the valve body 72 moves in the direction of increasing the opening degree of the throttle hole 71. In the present embodiment, the valve body 72 is configured not to completely close the throttle hole 71 even when the temperature of the working fluid in the evaporation side connecting portion 61 rises.

  In the present embodiment, when the temperature of the working fluid becomes high, the throttle opening of the variable throttle 7b becomes small, so that the amount of recovered heat is limited. Further, when the temperature of the working fluid becomes low, the throttle opening of the variable throttle 7b becomes large, so that the amount of recovered heat is not limited. Thereby, the effect similar to the said 2nd Embodiment can be acquired.

(Fourth embodiment)
Next, a fourth 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 fourth embodiment. As shown in FIG. 4, a variable throttle 7 c that changes the throttle opening according to the temperature of the cooling water is disposed in the evaporation side connecting portion 61. The variable throttle 7c is configured to reduce the throttle opening according to the temperature rise of the cooling water, that is, to reduce the passage cross-sectional area of the passage through which the working fluid flows.

  The variable throttle 7c has a valve body 75 provided in the evaporation side connecting portion 61, and a valve seat 76 with which the valve body 75 contacts and separates. The variable throttle 7c adjusts the throttle opening by changing the cross-sectional area of the minimum working fluid passage A formed by the valve body 75, the valve seat 76, and the gap.

  More specifically, one end of the temperature-sensitive deformation member 77 is fixed to the surface of the valve body 75 opposite to the surface facing the valve seat 76. The temperature-sensitive deformation member 77 is provided in the second housing 200 and is in direct contact with the cooling water. The other end of the temperature sensitive deformation member 77 is fixed to a support member 78 disposed in the second housing 200. The temperature-sensitive deformation member 77 is made of, for example, a thermometal made of a metal having a higher thermal expansion coefficient than that of the metal constituting the second casing 200, thermowax, or the like, and the temperature of the cooling water is predetermined. When it exceeds the temperature, it expands thermally.

  Therefore, when the temperature of the cooling water rises, the valve body 75 moves in the direction of reducing the passage cross-sectional area of the minimum working fluid passage A. On the other hand, when the temperature of the cooling water decreases, the valve body 75 moves in the direction of increasing the passage sectional area of the minimum working fluid passage A. In this embodiment, even if the temperature of the cooling water rises, the valve body 75 and the valve seat 76 do not come into complete contact, that is, the passage sectional area of the minimum working fluid passage A does not become zero. It is configured.

  In the present embodiment, when the temperature of the cooling water becomes high, the throttle opening of the variable throttle 7c becomes small, so that the amount of recovered heat is limited. For this reason, since the amount of recovered heat can be limited when the temperature of the cooling water is high in the summer when the engine is heavily loaded, overheating can be avoided.

  On the other hand, when the temperature of the cooling water becomes low, the throttle opening of the variable throttle 7c becomes large, so that the amount of recovered heat is not limited. For this reason, the cooling water temperature can be raised at an early stage, for example, at the start of the winter when the temperature of the cooling water is low, and the fuel consumption and heating performance can be improved.

(Other embodiments)
In the first embodiment, the example in which the fixed throttle 7 is formed on the throttle member 70 has been described. However, the present invention is not limited to this, and the fixed throttle 7 may be formed by partially reducing the inner diameter of the evaporation side connecting portion 61. . In this case, the diaphragm member 70 is unnecessary, and an increase in the number of parts can be suppressed.

  In the first embodiment, the throttle member 70 is formed in such a shape that the cross-sectional area of the flow path through which the working fluid evaporated in the evaporation unit 1 passes is gradually reduced and then gradually increased. Although it demonstrated, it is not restricted to this, You may form the aperture member 70 in a cylindrical shape.

  In the second and third embodiments, the variable throttles 7a and 7b are arranged so as to be in direct contact with the working fluid, and the throttle openings of the variable throttles 7a and 7b are mechanically controlled according to the temperature of the working fluid. However, the present invention is not limited to this, and a temperature sensor that detects the working fluid temperature in the evaporation side connecting portion 61 is provided, and the throttle openings of the variable throttles 7a and 7b are based on the temperature detected by the temperature sensor. It may be electrically controlled.

  Similarly, in the fourth embodiment, the variable throttle 7c is arranged so as to be in direct contact with the cooling water, and the throttle openings of the variable throttles 7a and 7b are mechanically controlled according to the temperature of the cooling water. Although described above, the present invention is not limited to this, and a temperature sensor for detecting the cooling water temperature in the second casing 200 is provided, and the throttle opening of the variable throttle 7c is electrically controlled based on the detected temperature of the temperature sensor. You may make it do.

It is sectional drawing which shows the exhaust heat recovery device which concerns on 1st Embodiment. It is an expanded sectional view which shows the vapor | steam side connection part 61 of the exhaust heat recovery device which concerns on 2nd Embodiment, (a) is the time of working fluid high temperature, (b) has shown the time of working fluid low temperature. It is an expanded sectional view showing steam side connecting part 61 of an exhaust heat recovery device concerning a 3rd embodiment. It is sectional drawing which shows the exhaust heat recovery device which concerns on 4th Embodiment. It is sectional drawing which shows the conventional exhaust heat recovery device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Evaporating part, 2 ... Condensing part, 7 ... Fixed aperture (throttle mechanism), 7a-7c ... Variable aperture (throttle mechanism), 61 ... Evaporation side connection part, 62 ... Condensation side connection part.

Claims (4)

The exhaust gas exhausted from the internal combustion engine is disposed in an exhaust gas passage through which heat is exchanged between the exhaust gas and an evaporating and condensable working fluid enclosed therein to evaporate the working fluid. An evaporation section (1);
A condensing unit 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 unit (1) and the cooling water to condense the working fluid. (2) and
An evaporation side connecting part (61) for guiding the working fluid evaporated in the evaporation part (1) to the condensing part (2);
A condensing side connecting part (62) for guiding the working fluid condensed in the condensing part (2) to the evaporating part (1),
The exhaust-side heat recovery device is characterized in that a throttle mechanism (7, 7a to 7c) is provided in the evaporation side connecting portion (61). The exhaust heat recovery device according to claim 1, wherein the throttle mechanism is a fixed throttle (7). The exhaust heat recovery device according to claim 1, wherein the throttle mechanism is a variable throttle (7a to 7c) that changes a throttle opening according to a temperature of the cooling water or a temperature of the working fluid. The said variable throttle (7a-7c) is comprised so that the said throttle opening may be made small according to the temperature rise of the said cooling water, or the temperature rise of the said working fluid. Exhaust heat recovery unit.

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