JP2015031240A - Exhaust heat recovery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pressure loss of exhaust gas for heat exchange by curbing influence of wind generated by travel motion or a reduction of recovery efficiency of heat quantity of high temperature cooling water and to easily and reliably control recovered heat quantity.SOLUTION: An exhaust heat recovery device 1 comprises: an inner cylinder section 4 with cooling water 3 flowing inside the same; an outer cylinder section 5 arranged at an outer peripheral section of the inner cylinder section 4 with a space in between; and a third cylinder section 6 arranged with a distance from the outer cylinder section 5 with the cooling water 3 flowing inside the same. An exhaust gas flow passage 9 where exhaust gas 2 flows therein is formed in a gap between the outer peripheral section of the inner cylinder section 4 and an inner peripheral section of the outer cylinder section 5. The inner cylinder section 4 is connected to the third cylinder section 6 at an upstream section 14a and a downstream section 14b of a cooling water circulation passage 14 where the cooling water 3 flows therein. A control valve 15 which controls a flow rate of the cooling water 3 flowing inside the inner cylinder section 4 and the third cylinder section 6 is installed on the upstream section 14a of the cooling water circulation passage 14.

Description

  The present invention relates to an exhaust heat recovery device for recovering heat of exhaust gas of an engine.

Conventionally, as a device for recovering heat of exhaust gas of an internal combustion engine for automobiles (hereinafter referred to as an engine), heat of exhaust gas from an engine that is interposed in the middle of the exhaust pipe of the engine and passes through the exhaust pipe (hereinafter referred to as “engine”). There is known an exhaust heat recovery device that recovers exhaust heat) into an engine cooling medium (for example, engine cooling water; hereinafter referred to as cooling water) by heat exchange. The exhaust heat recovered via the engine cooling water is used, for example, to rapidly increase the temperature of the cooling water when the engine is cold at the initial start of the engine in order to complete the warm-up operation of the engine at an early stage. It is also used for heating the passenger compartment.
On the other hand, when heat recovery is not necessary, the flow path in the exhaust heat recovery device is switched by an exhaust valve or the like, guided to the bypass flow path, and exhaust gas is discharged straight downstream without going through the heat recovery section. This suppresses the increase in pressure loss.

By the way, as a type of exhaust heat recovery devices currently in practical use, an exhaust heat recovery device as shown in FIG. 5 (see, for example, Patent Document 1) and an exhaust heat recovery device as shown in FIG. Patent Document 2).
That is, as shown in FIG. 5, the exhaust heat recovery device 50 of Patent Document 1 includes an inner cylinder portion 53 in which an exhaust gas passage 52 through which the exhaust gas 51 passes is formed, and a downstream side of the inner cylinder portion 53. Provided between the inner cylinder part 53 and the outer cylinder part 55, an exhaust valve 54 that opens and closes the exhaust gas passage 52, an outer cylinder part 55 that is provided on the outer peripheral side of the inner cylinder part 53 with a space therebetween. Heat exchange sections (exhaust heat recovery passages 56a and 56b and cooling water passages 57a and 57b). Reference numeral 58 denotes cooling water.
When the exhaust heat is recovered, the exhaust valve 54 is closed, and the exhaust gas 51 introduced into the inner cylinder portion 53 is exhausted from the small hole 59 to the exhaust heat recovery portion located on the outer periphery of the inner cylinder portion 53. Heat is exchanged between the cooling water 58 flowing into the flow paths 56a and 56b and flowing through the cooling water flow paths 57a and 57b. On the other hand, when the need for warm-up operation or heating has declined after a certain period of time has elapsed since the start of the engine, the exhaust valve 54 is opened, and exhaust heat is not collected without going through the heat exchange part in contact with the cooling water 58, The exhaust gas 51 introduced into the inner cylinder part 53 is directly discharged to the downstream side.

Further, as shown in FIG. 6, the exhaust heat recovery device 60 of Patent Document 2 is provided with a branch portion having exhaust valves 62 and 63 in one exhaust gas flow channel 61, and includes a flow including the exhaust heat recovery device 60. The passage 61a and the bypass passage 61b for discharging the exhaust gas are arranged in parallel, and are configured so as to merge again into one exhaust gas passage on the downstream side. Reference numeral 64 denotes an exhaust manifold, and reference numeral 65 denotes a converter.
When exhaust heat recovery is performed, the exhaust valve 62 is opened, the exhaust valve 63 is closed, and the exhaust gas is caused to flow through the flow path 61 a including the exhaust heat recovery device 60. On the other hand, when exhaust heat is exhausted, the exhaust valve 62 is closed, the exhaust valve 63 is opened, and the exhaust gas flows into the bypass flow path 61b that exhausts the exhaust gas and is exhausted.

JP 2010-31671 A JP 2001-30741 A

There is a demand for such an exhaust heat recovery device to utilize the heat of exhaust gas for improving fuel efficiency even after achieving the objectives of warming up the engine and heating the passenger compartment. For example, in a vehicle equipped with a Rankine cycle (steam cycle) system that aims to improve fuel efficiency by converting the thermal energy of exhaust gas into mechanical energy, the cooling water that recovered the exhaust gas heat is used to heat the Rankine cycle system. It can be used as a heat source for the oven.
Here, in order to use the exhaust heat in the Rankine cycle system, it is necessary to continuously recover the exhaust heat during steady engine operation or high load operation. Moreover, the Rankine cycle system is required not only to continuously recover the exhaust heat with the exhaust heat recovery device during steady operation of the engine, but also to be able to easily control the amount of exhaust heat recovered.
The Rankine cycle system is an example of an exhaust heat recovery method. Besides this, there are various methods such as adsorption refrigerator, chemical heat storage, thermoacoustic power generation, Stirling engine, thermoelectric power generation, including all of these, This is called the “Rankin cycle system”.

However, the exhaust heat recovery devices 50 and 60 of Patent Documents 1 and 2 described above have the following three problems.
First, in a vehicle in which an engine is mounted on the front part of the vehicle body, the exhaust pipe is led from the front part of the vehicle body to the rear of the vehicle through the lower surface of the vehicle body. It will be. However, in the configuration of Patent Document 1, since the cooling water channels 57 a and 57 b are arranged so as to cover the exhaust gas channel 52, the cooling water 58 not only contacts the exhaust gas 51 but also passes through the outer cylinder portion 55. It is also in contact with outside air. Therefore, there are the following problems. This also applies to the configuration of Patent Document 2.
The cooling water 58 collects exhaust heat at a portion in contact with the exhaust gas 51, but dissipates the collected exhaust heat at a portion in contact with outside air. For example, when the flow of the traveling wind becomes faster during steady operation or high speed operation of the engine, the cooling water 58 is further cooled, and the exhaust heat collected at the corner is further dissipated. In other words, since heat loss to the outside air occurs, the exhaust heat recovery efficiency decreases.
In addition, the temperature of the cooling water 58 rises after a certain period of engine operation, but when the temperature of the cooling water 58 rises, the temperature difference between the cooling water 58 and the outside air becomes large. Further, the amount of heat released from the cooling water 58 to the outside air increases, and the same problem as described above occurs.

Secondly, in the configuration of Patent Document 1, the exhaust gas 51 flows out to the first exhaust heat recovery flow path 56a through the small hole 59, turns back immediately after that, and then turns back to flow upstream on the second side. It is led to the exhaust heat recovery flow path 56b. Therefore, the pressure loss of the exhaust gas 51 becomes large. As a result, the output at the time of high engine load is reduced and the fuel consumption is deteriorated.
Third, in the configuration of Patent Document 2, the exhaust gas flow path is narrowed due to heat exchange in the exhaust heat recovery device 60, and fins and the like that intentionally disturb the flow in the exhaust gas flow path are arranged. Pressure loss will increase. As a result, the same problem as described in the second case occurs.

  The present invention has been made in view of such a situation, and its purpose is to prevent the influence of traveling wind or decrease in the recovery efficiency of the heat quantity of high-temperature cooling water, and to reduce the pressure loss of exhaust gas for heat exchange. An object of the present invention is to provide an exhaust heat recovery device that can reduce the amount of recovered heat and can control the amount of recovered heat easily and reliably.

  In order to solve the above-described problems of the related art, the present invention includes an inner cylinder part in which a cooling medium flows, an outer cylinder part arranged at an interval on an outer peripheral part of the inner cylinder part, An exhaust heat recovery device including a third cylindrical portion that is disposed at a distance from the cylindrical portion and in which a cooling medium flows, and includes an outer peripheral portion of the inner cylindrical portion and an inner peripheral portion of the outer cylindrical portion. A space in which exhaust gas flows is formed therebetween, and the inner cylinder part and the third cylinder part are respectively connected at an upstream part and a downstream part of a cooling medium flow path through which the cooling medium flows, A control valve for controlling the flow rate of the cooling medium flowing in the inner cylinder part and the third cylinder part is provided upstream of the cooling medium flow path.

  In the present invention, the cooling medium always flows inside the inner cylinder portion by controlling the flow rate of the control valve.

  Furthermore, in the present invention, the control valve is a three-way valve with a stopper.

In the present invention, fins are provided on the outer peripheral portion of the inner cylindrical portion and the outer peripheral portion of the third cylindrical portion.
In the present invention, the total surface area of the fins of the inner cylinder part is set smaller than the total surface area of the fins of the third cylinder part.

Moreover, in this invention, the stirring apparatus which stirs the said cooling medium is provided in at least one inside of the said inner cylinder part and the said 3rd cylinder part.
Moreover, in the present invention, the stirring device is a static mixer.

  As described above, the exhaust heat recovery device according to the present invention includes an inner cylinder portion in which a cooling medium flows, an outer cylinder portion arranged at an outer periphery of the inner cylinder portion, and the outer cylinder portion. And a third cylinder part in which the cooling medium flows inside, between the outer peripheral part of the inner cylinder part and the inner peripheral part of the outer cylinder part. A space in which exhaust gas flows is formed, and the inner cylinder portion and the third cylinder portion are respectively connected in an upstream portion and a downstream portion of a cooling medium flow path in which the cooling medium flows, and the cooling medium flow Since the control valve for controlling the flow rate of the cooling medium flowing in the inner cylinder part and the third cylinder part is provided in the upstream part of the path, the following effects can be obtained. it can.

That is, in the exhaust heat recovery device of the present invention, the inside of the inner cylinder part is covered by the flow space of the exhaust gas formed between the outer peripheral part of the inner cylinder part and the inner peripheral part of the outer cylinder part. Since it is not exposed, it can suppress that the heat | fever of the exhaust gas collect | recovered by the cooling medium thermally radiates to external air with a vehicle running wind. That is, heat radiation from the cooling medium to the outside air is reduced. Therefore, according to the exhaust heat recovery device of the present invention, it is possible to prevent the loss of the amount of heat recovered in the cooling medium, so that the exhaust heat recovery efficiency can be improved. In addition, even if the engine has been running for a certain period of time and the temperature of the cooling medium rises, the inner cylinder is not exposed to the outside air that causes the loss of heat, thus preventing the loss of heat recovered in the cooling medium. It is possible to improve the exhaust heat recovery efficiency.
In addition, in the exhaust heat recovery device of the present invention, the exhaust valve disposed inside the exhaust gas flow path in the conventional exhaust heat recovery device can be eliminated, so the pressure generated in the exhaust valve Loss can be removed and pressure loss can be reduced. Furthermore, the space where the exhaust gas flows can be formed in a linear shape by eliminating the exhaust valve. As a result, the flow of the exhaust gas inside the space becomes smooth, and the pressure loss due to the generation of vortices due to the presence of the exhaust valve and the bend in the conventional exhaust heat recovery device can be reduced. Furthermore, according to the exhaust heat recovery device of the present invention, the exhaust gas smoothly flows inside the space. Therefore, the size of the cross-sectional area of the exhaust gas flow path inside the space, the number of fins to be described later, or the density of fins The degree of freedom of setting such as degree can be increased. As a result, the exhaust gas flow path flowing in the space can be designed to reduce the pressure loss of the exhaust gas, so that the pressure loss of the exhaust gas can be further reduced.
In addition, in the exhaust heat recovery device of the present invention, the control valve distributes the ratio of the flow rate of the cooling medium flowing through the inside of the inner cylinder part that is the exhaust heat recovery part and the inside of the third cylinder part that is the heat dissipation part. Therefore, it is possible to easily and reliably control the recovered heat amount of the exhaust gas to the cooling medium. Therefore, even when the heat of the exhaust gas recovered in the cooling medium is used as a heat source for the heater of the Rankine cycle system, it is possible to quickly respond to the control of the heat amount that is required by the Rankine cycle system.

  In addition, since the cooling medium always flows inside the inner cylinder part by controlling the flow rate of the control valve, the cooling medium overheats and the cooling medium stays inside the inner cylinder part. It is possible to prevent the occurrence of abnormalities in the engine caused by the sudden boiling of the cooling medium.

  Furthermore, in the present invention, since the control valve can be a three-way valve with a stopper, by adjusting the stopper, a small flow rate of cooling medium is always allowed to flow into the inner cylinder part which is the exhaust heat recovery part. It becomes possible. Therefore, it is possible to prevent the cooling medium from overheating inside the inner cylinder portion, and in turn, to stay in the cooling medium that causes bumping. As a result, it is possible to effectively prevent engine abnormality caused by cooling medium circulation failure induced by cooling medium bumping and damage to the cooling medium system due to pressure fluctuation.

In the present invention, since fins are provided on the outer peripheral portion of the inner cylindrical portion and the outer peripheral portion of the third cylindrical portion, the cooling medium flowing inside the inner cylindrical portion efficiently uses the heat of the exhaust gas. Can be recovered efficiently, and heat can be efficiently radiated from the cooling medium flowing inside the third cylindrical portion to the outside air.
Moreover, in the present invention, the total surface area of the fins of the inner cylinder portion is set smaller than the total surface area of the fins of the third cylinder portion, so that the heat recovery amount of the exhaust gas heat inside the inner cylinder portion And the amount of heat released to the outside air inside the third cylindrical portion can be made substantially equal. That is, the temperature of the cooling medium after distribution of the cooling mediums of the inner cylinder part and the third cylinder part to the inner cylinder part and the third cylinder part (before branching) The exhaust heat recovery heat quantity can be easily controlled while preventing a load from being applied to the radiator located downstream of the cooling medium flow path.

Furthermore, in this invention, since the stirring apparatus which stirs the said cooling medium is provided in at least any one inside the said inner cylinder part and the said 3rd cylinder part, the heat transfer rate of a cooling medium Improvements can be made. That is, the exhaust heat recovery efficiency inside the inner cylinder part and the heat radiation efficiency to the outside air inside the third cylinder part can be increased.
Moreover, in the present invention, since the stirring device can be a static mixer, the cooling medium flowing inside can be reliably stirred, and the exhaust gas flowing in the space outside the outer peripheral portion of the inner tube portion and the inner tube portion It is possible to improve the efficiency of heat exchange with the cooling medium flowing inside, and to increase the amount of heat recovered from the exhaust gas by the cooling medium.

It is a conceptual diagram which shows the whole exhaust heat recovery device which concerns on embodiment of this invention. In the exhaust heat recovery device concerning the embodiment of the present invention, it is a key map showing the flow of the cooling water at the time of engine starting. In the exhaust heat recovery device concerning the embodiment of the present invention, it is a key map showing the flow of the cooling water at the time of engine steady operation or engine high load operation. It is a three-way valve with a stopper provided in the exhaust heat recovery device concerning the embodiment of the present invention, (a) is a sectional view in the state where the flow path of the cooling water was changed from A to B by rotation of the ball, (b) It is sectional drawing of the state which changed the flow path of the cooling water from A to C by rotation of the ball | bowl. It is sectional drawing which shows the conventional exhaust heat recovery device. It is sectional drawing which shows the other conventional exhaust heat recovery device.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
1 to 4 show an exhaust heat recovery device according to an embodiment of the present invention. 1 to 3, the arrow Fr direction indicates the vehicle front side, and the arrow Re direction indicates the vehicle rear side.

As shown in FIGS. 1 to 3, the exhaust heat recovery device 1 according to the present embodiment is used not only at the start of an automobile engine (not shown) but also at the time of steady operation or high load operation of the engine. The cooling water (cooling medium) 3 recovers the heat of the exhaust gas 2 flowing from the engine to the vehicle rear side from the side, and this recovered heat is used to warm up the engine, heat the vehicle interior, and heat source of the Rankine cycle heater It is used for.
For this reason, as shown in FIG. 1, the exhaust heat recovery device 1 of the present embodiment has a horizontal inner cylinder portion 4 in which the cooling water 3 flows, and a predetermined amount on the outer peripheral side of the inner cylinder portion 4. A laterally placed outer cylinder part 5 arranged at an interval, and a laterally arranged third cylinder part 6 arranged in parallel at a predetermined interval from the outer cylinder part 5 and in which the cooling water 3 flows. The inner cylinder part 4, the outer cylinder part 5, and the third cylinder part 6 are provided to extend in the vehicle front-rear direction. Further, the third cylinder portion 6 is arranged on either the upper side or the lower side in the vehicle vertical direction with respect to the inner cylinder portion 4 and the outer cylinder portion 5, or on the left side or the right side in the vehicle width direction. Has been placed.

  As shown in FIGS. 1 to 3, the inside of the inner cylinder portion 4 of the present embodiment is formed as a first cooling water passage 7 through which the cooling water 3 flows. A static mixer 8 serving as a stirring device for stirring the water 3 is provided. In the static mixer 8, a plurality of right twist blades 8a twisted in the right direction and a plurality of left twist blades 8b twisted in the left direction are joined while being alternately arranged in the axial direction (vehicle longitudinal direction). It is configured. The cooling water 3 flowing in the first cooling water flow path 7 is rotated and stirred by the blades 8a and 8b. When the cooling water 3 flowing in the first cooling water flow path 7 is stirred, the heat exchange efficiency with the exhaust gas 2 flowing outside the inner cylinder portion 4 is improved, and the amount of heat recovered by the cooling water 3 in the exhaust gas 2 is increased. Will be.

  Further, an exhaust gas passage 9 that is a space in which the exhaust gas 2 flows is formed along the vehicle front-rear direction between the outer peripheral portion of the inner cylindrical portion 4 and the inner peripheral portion of the outer cylindrical portion 5. The exhaust gas passage 9 covers the first cooling water passage 7 inside the inner cylinder portion 4 and is configured not to be exposed to the outside air 10. For this reason, the heat of the exhaust gas 2 introduced into the exhaust gas passage 9 is recovered into the cooling water 3 flowing through the first cooling water passage 7 inside the inner cylinder portion 4 by heat exchange, and the cooling water 3 The exhaust heat recovery section X is configured such that the heat of the exhaust gas 2 recovered in the above is suppressed from being radiated to the outside air 10 by the vehicle traveling wind 11.

  Further, as shown in FIGS. 1 to 3, the inside of the third cylindrical portion 6 is formed as a second cooling water flow path 12 through which the cooling water 3 flows, and in the second cooling water flow path 12, Similar to the 1 cooling water flow path 7, a static mixer 13 of a stirring device for stirring the cooling water 3 is provided. The static mixer 13 has the same structure as the static mixer 8 of the first cooling water flow path 7, and a plurality of right twist blades 13a twisted in the right direction and a plurality of left twist blades 13b twisted in the left direction. Are joined together while being alternately arranged in the axial direction (vehicle longitudinal direction). The cooling water 3 flowing in the second cooling water flow path 12 is rotated by the blades 13a and 13b, and the cooling water 3 is stirred. When the cooling water 3 flowing in the second cooling water flow path 12 is agitated, the efficiency of heat exchange with the outside air 10 including the vehicle traveling wind 11 flowing outside the third cylindrical portion 6 is improved and recovered in the cooling water 3. The heat of the exhaust gas 2 is a heat radiating part Y that radiates heat to the outside air 10 by the vehicle traveling wind 11 or the like.

  As shown in FIGS. 1 to 3, the inner cylinder portion 4 and the third cylinder portion 6 in the exhaust heat recovery device 1 of the present embodiment are a cooling water circulation channel (cooling medium channel) through which the cooling water 3 flows. 14 are connected by an upstream portion 14a and a downstream portion 14b. That is, the upstream part 14 a and the downstream part 14 b of the cooling water circulation channel 14 communicate with the first cooling water channel 7 of the inner cylinder part 4 and the second cooling water channel 12 of the third cylinder part 6. The upstream end of the cooling water circulation passage 14 is connected to a cooling water pump (not shown), and the downstream end of the cooling water circulation passage 14 is connected to an engine and a radiator (not shown). It is comprised so that it may circulate to an engine and a radiator.

As shown in FIGS. 1 to 3, in the upstream portion 14 a of the cooling water circulation channel 14, cooling flows through the first cooling water channel 7 of the inner cylinder portion 4 and the second cooling water channel 12 of the third cylinder portion 6. A control valve 15 for controlling the flow rate of the water 3 is provided. The control valve 15 can be a three-way valve with a stopper. By adjusting the stopper, the second cooling water flow path 12 of the third cylindrical portion 6 in which the total flow rate of the cooling water 3 is the heat radiating portion Y is provided. The cooling water 3 is sent to the first cooling water flow path 7 of the inner cylinder part 4 which is the exhaust heat recovery part X and is always guaranteed to flow even at a small flow rate. That is, as shown in FIG. 4, the control valve 15 is normally used for switching the flow path such as “A → B” or “A → C”. It is possible to flow through a flow path called “C”, and this phenomenon is utilized in this embodiment.
Therefore, the control valve 15 is provided with a stopper (not shown) for restricting the rotation of the ball 15a to the B side, and even when the ball 15a is turned to the B side as shown in FIG. This stopper ensures not only the flow of “A → B” but also the flow of “A → B (maximum flow rate) and C (small flow rate)”. On the other hand, as shown in FIG. 4B, no stopper is provided in the direction in which the ball 15a is turned to the C side, and the first cooling water passage 7 of the inner cylinder portion 4 that is the exhaust heat recovery portion X is cooled. The entire flow rate of the water 3 is configured to flow. As a result, overheating of the cooling water 3 in the first cooling water flow path 7 inside the inner cylinder portion 4 and retention of the cooling water 3 that causes bumping are prevented, and an engine abnormality caused by a circulation failure of the cooling water 3 It prevents generation and damage to the cooling water system due to pressure fluctuations.

As shown in FIGS. 1 to 3, a large number of fins 16 and 17 are provided on the outer peripheral portion of the inner cylindrical portion 4 and the outer peripheral portion of the third cylindrical portion 6 of the present embodiment. The fins 16 of the inner cylinder part 4 are provided so that the cooling water 3 flowing through the first cooling water flow path 7 inside can efficiently recover the heat of the exhaust gas 2, and the fins 17 of the third cylinder part 6 are It is provided for efficiently radiating heat from the cooling water 3 flowing through the internal second cooling water flow path 12 to the outside air 10.
Further, in the exhaust heat recovery device 1 of the present embodiment, the total surface area of the fins 16 of the inner cylinder part 4 is set smaller than the total surface area of the fins 17 of the third cylinder part 6, in other words, the heat dissipation part. The total surface area of the fins 17 of the third cylinder part 6 is set to be larger than the total surface area of the fins 16 of the inner cylinder part 4 that is the exhaust heat recovery part X, and Rankine is used during steady operation or high load operation of the engine. When there is no heat request from the cycle system (when more than half of the cooling water 3 is sent to the second cooling water flow path 12 inside the third cylindrical portion 6 which is the heat radiating portion Y), the inside of the inner cylindrical portion 4 The amount of heat recovered from the heat of the exhaust gas 2 by the cooling water 3 flowing through the first cooling water flow path 7 and the heat radiation from the cooling water 3 flowing through the second cooling water flow path 12 inside the third cylindrical portion 6 to the outside air 10 It is comprised so that a calorie | heat amount may become substantially equivalent. Thereby, the temperature of the cooling water 3 after the respective cooling waters 3 of the first cooling water channel 7 of the inner cylinder part 4 and the second cooling water channel 12 of the third cylinder part 6 merge is It becomes possible to make the temperature substantially the same as the temperature of the cooling water 3 before distribution (before branching) to the first cooling water flow path 7 and the second cooling water flow path 12 of the third cylindrical portion, and downstream of the cooling water circulation flow path 14. No load is applied to the radiator (not shown) located on the side.
Further, when there is a heat request from the Rankine cycle system, the cooling water 3 is supplied to the first cooling water flow path 7 of the inner cylinder portion 4 and the second cooling inside the third cylinder portion 6 according to the required amount of heat. It can be distributed to the water flow path 12 so that the exhaust heat recovery heat quantity can be easily controlled.

  For example, when the temperature of the cooling water 3 is about 100 ° C., the temperature of the exhaust gas 2 around the first cooling water flow path 7 of the inner cylinder portion 4 is about 300 ° C., so the temperature difference from the cooling water 3 is about 200 ° C. On the other hand, since the temperature of the outside air 10 around the second cooling water flow path 12 inside the third cylindrical portion 6 is about 30 ° C., the temperature difference from the cooling water 3 is about 70 ° C. If the total surface area of the fins 16 of the inner cylinder part 4 and the total surface area of the fins 17 of the third cylinder part 6 are set to be the same, the heat dissipation amount of the second cooling water channel 12 in the third cylinder part 6 Is about half the amount of heat recovered by the first cooling water flow path 7 in the inner cylinder portion 4. The larger the area, the larger the amount of heat that is transmitted, so that the recovered heat amount of the first cooling water channel 7 in the inner cylinder part 4 and the heat dissipation amount of the second cooling water channel 12 in the third cylinder part 6 are substantially equal. The total surface area of the fins 17 of the third cylindrical part 6 needs to be set larger than the total surface area of the fins 16 of the inner cylindrical part 4.

Next, the operation and action of the exhaust heat recovery device 1 according to the embodiment of the present invention will be described.
First, when there is a request for warming up the engine or heating the passenger compartment at the time of starting the engine, the control valve 15 provided in the upstream portion 14a of the cooling water circulation passage 14 is controlled as shown in FIG. Thus, the entire amount of the cooling water 3 is sent from the upstream portion 14a of the cooling water circulation passage 14 to the first cooling water passage 7 of the inner cylinder portion 4 that is the exhaust heat recovery portion X, and the third cylinder portion that is the heat radiating portion Y. The cooling water 3 is not sent to the second cooling water flow path 12. The cooling water 3 sent to the first cooling water flow path 7 exchanges heat with the exhaust gas 2 flowing through the exhaust gas flow path 9 outside the inner cylinder portion 4 while flowing through the first cooling water flow path 7, thereby The heat of gas 2 is recovered. After the heat recovery, the cooling water 3 flows out from the first cooling water flow path 7 of the inner cylinder part 4 and is sent to a radiator (not shown) through the downstream part 14b of the cooling water circulation flow path 14 as it is. It will be.

Further, when there is no request for warming up the engine or heating the passenger compartment during steady engine operation or high load operation, as shown in FIG. 3, the control provided in the upstream portion 14a of the cooling water circulation passage 14 is provided. By controlling the valve 15, the cooling water 3 having a flow rate of more than half is sent from the upstream portion 14 a of the cooling water circulation passage 14 to the second cooling water passage 12 of the third cylindrical portion 6 that is the heat radiating portion Y. A small flow amount of the cooling water 3 is sent to the first cooling water flow path 7 of the inner cylinder part 4 which is the exhaust heat recovery part X. The small flow rate of the cooling water 3 sent to the first cooling water channel 7 exchanges heat with the exhaust gas 2 flowing through the exhaust gas channel 9 outside the inner cylinder part 4 while flowing through the first cooling water channel 7. In order to recover the heat of the exhaust gas 2, the first cooling water passage 7 inside the inner cylinder portion 4 is overheated by the heat of the exhaust gas 2 flowing through the exhaust gas passage 9 outside the inner cylinder portion 4. It will be prevented.
The small flow rate of cooling water 3 that has recovered heat flows out from the first cooling water flow path 7 of the inner cylinder portion 4, while the large flow rate of cooling water 3 sent to the second cooling water flow path 12 While flowing through the second cooling water flow path 12 of the cylindrical portion 6, the heat is released to the outside air 10 by the vehicle traveling wind 11 flowing outside the third cylindrical portion 6 and flows out from the second cooling water flow path 12. And the cooling water 3 which flowed out from the 2nd cooling water flow path 12 merges with the cooling water 3 which flowed out from the 1st cooling water flow path 7, and is sent to the radiator outside a figure through the downstream part 14b of the cooling water circulation flow path 14. FIG. It will be. At this time, since the third cylinder portion 6 that is the heat radiating portion Y is exposed to the vehicle traveling wind 11 that increases in proportion to the vehicle speed, the cooling water 3 flowing through the second cooling water flow path 12 is proportional to the vehicle speed. Will be cooled. Moreover, since the total surface area of the fins 17 provided on the outer peripheral part of the third cylindrical part 6 is set to be larger than the total surface area of the fins 16 provided on the outer peripheral part of the inner cylindrical part 4, The amount of heat recovered from the heat of the exhaust gas 2 by the cooling water 3 flowing through the first cooling water flow path 7 of the cylindrical portion 4 and the outside air 10 from the cooling water 3 flowing through the second cooling water flow path 12 of the third cylindrical portion 6 It is possible to make the heat radiation amount substantially equal. Thereby, the temperature after the cooling water 3 flowing out from the first cooling water flow path 7 of the inner cylinder portion 4 and the cooling water 3 flowing out from the second cooling water flow path 12 of the third cylindrical portion 6 merges, It becomes possible to make the temperature substantially the same as the temperature of the cooling water 3 before the distribution to the first cooling water flow path 7 and the second cooling water flow path 12 (before branching), and a radiator ( (Not shown) does not increase, and the exhaust heat recovery heat quantity can be easily controlled.

  Thus, in the exhaust heat recovery device 1 according to the embodiment of the present invention, the exhaust gas flow path 9 which is a space formed between the outer peripheral portion of the inner cylindrical portion 4 and the inner peripheral portion of the outer cylindrical portion 5 is used. Since the first cooling water flow path 7 inside the inner cylinder portion 4 is covered and not directly exposed to the outside air 10, the heat of the exhaust gas 2 collected in the cooling water 3 is radiated to the outside air 10 by the vehicle traveling wind 11. The amount of heat released from the cooling water 3 to the outside air 10 can be reduced, and the heat recovery efficiency of the exhaust gas 2 can be improved. Further, in the exhaust heat recovery device 1 of the present embodiment, it is not necessary to arrange an exhaust valve inside the exhaust gas flow path 9, so that the pressure loss generated in the exhaust valve is reduced and the pressure loss is kept low. be able to. Further, by eliminating the exhaust valve, it is possible to form the exhaust gas passage 9 in a straight shape so that the exhaust gas 2 in the exhaust gas passage 9 can flow smoothly, and the pressure loss due to the generation of vortices can be reduced. In addition, the degree of freedom of selection and setting such as the size of the cross-sectional area of the exhaust gas passage 9, the number of fins 16 and 17 arranged, and the density of the fins 16 and 17 can be increased. Furthermore, in the exhaust heat recovery device 1 of the present embodiment, the first cooling water passage 7 of the inner cylinder portion 4 that is the exhaust heat recovery portion X and the second cooling water passage of the third cylinder portion 6 that is the heat radiating portion Y. Since the ratio of the flow rate of the cooling water 3 flowing through 12 is configured to be distributed by the control valve 15, the amount of heat of the exhaust gas 2 recovered in the cooling water 3 can be easily and reliably controlled. Thus, the heat of the exhaust gas 2 recovered can be used without any problem as a heat source for the heater of the Rankine cycle system.

While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention.
For example, the control valve 15 of the above-described embodiment is not limited to a three-way valve with a stopper as shown in FIG. 4, but may be another type of three-way valve as long as it can perform the same function. Also good.

1 Exhaust heat recovery device 2 Exhaust gas 3 Cooling water (cooling medium)
4 inner cylinder part 5 outer cylinder part 6 3rd cylinder part 7 1st cooling water flow path (inside of inner cylinder part)
8,13 Static mixer (stirrer)
9 Exhaust gas passage (space)
10 Outside air 11 Vehicle running wind 12 Second cooling water flow path (inside the third cylinder)
14 Cooling water circulation channel (cooling medium channel)
14a Upstream part 14b Downstream part 15 Control valve 16, 17 Fin X Exhaust heat recovery part Y Heat radiation part

Claims (7)

An inner cylinder part in which the cooling medium flows inside, an outer cylinder part that is spaced from the outer peripheral part of the inner cylinder part, and a space that is spaced from the outer cylinder part, and the cooling medium flows inside In the exhaust heat recovery device including the third cylindrical portion,
Between the outer peripheral part of the inner cylinder part and the inner peripheral part of the outer cylinder part, a space in which exhaust gas flows is formed,
The inner cylinder part and the third cylinder part are respectively connected at an upstream part and a downstream part of a coolant flow path through which the coolant flows.
Exhaust heat characterized by having a control valve for controlling the flow rate of the cooling medium flowing in the inner cylinder part and the third cylinder part in the upstream part of the cooling medium flow path. Collector.   2. The exhaust heat recovery device according to claim 1, wherein the cooling medium always flows inside the inner cylinder portion by controlling the flow rate of the control valve.   The exhaust heat recovery device according to claim 1 or 2, wherein the control valve is a three-way valve with a stopper.   The exhaust heat recovery device according to any one of claims 1 to 3, wherein fins are provided on an outer peripheral portion of the inner cylindrical portion and an outer peripheral portion of the third cylindrical portion.   The exhaust heat recovery device according to claim 4, wherein a total surface area of the fins of the inner cylinder part is set smaller than a total surface area of the fins of the third cylinder part.   6. The stirring device for stirring the cooling medium is provided in at least one of the inner tube portion and the third tube portion. 6. The exhaust heat recovery device described.   The exhaust heat recovery device according to claim 6, wherein the stirring device is a static mixer.

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