JP5130083B2 - Waste heat utilization device for internal combustion engine - Google Patents

Description

  The present invention relates to a waste heat utilization apparatus for an internal combustion engine, for example, a waste heat utilization apparatus for an internal combustion engine that is suitable for being incorporated in a vehicle.

  This type of internal combustion engine waste heat utilization device is mounted on a vehicle, for example, recovers energy from the waste heat of the engine via cooling water that cools the engine of the vehicle, and the evaporative refrigerant heated by this waste heat. Is provided with a Rankine cycle circuit (RC circuit) having a Rankine cycle capacitor (RC capacitor) that condenses the refrigerant that has passed through the expander with outside air, in order from the windward, An RC condenser and a radiator for receiving wind from the front of the vehicle are arranged to cool the coolant of the vehicle engine.

Similarly, when an air conditioner cycle is provided, an air conditioner cycle condenser (AC condenser) and a radiator are arranged from the windward side. However, an AC condenser is placed on the front side of the radiator, and a part of the wind is bypassed from the AC condenser. A technique for directly ventilating a radiator is disclosed (for example, Patent Document 1).
Japanese Patent No. 2924171

However, in the above prior art, although a part of the wind is allowed to flow around the condenser, no special consideration is given to the point where the radiator is bypassed, and the ventilation resistance of the entire exchange unit that performs heat exchange heat with the outside air is not considered. There are still challenges to reduce.
Further, in the above-described prior art, no special consideration is given to the possibility of downsizing the radiator, and thus the heat exchange unit, by dissipating the waste heat of the engine by both the radiator and the condenser.

  The present invention has been made in view of such a problem, and is a waste of an internal combustion engine that can reduce the ventilation resistance of the outside air in the entire heat exchange unit and can greatly improve the energy recovery efficiency while reducing the size. An object is to provide a heat utilization device.

In order to achieve the above object, a waste heat utilization apparatus for an internal combustion engine according to claim 1 is a cooling water circuit having a radiator for cooling the cooling water heated by the waste heat of the internal combustion engine by outside air, and heated by the cooling water. A waste heat utilization device for an internal combustion engine comprising: an expander that expands the generated refrigerant to generate a driving force; and a Rankine cycle that includes a condenser that condenses the refrigerant that has passed through the expander by ventilation of the outside air. from the direction of airflow in order, a capacitor, comprising a heat exchange unit which mutually overlap to exist a predetermined gap a radiator, heat exchanger units, have a bypass means to flow outside air after being ventilated to the capacitor to bypass the radiator The bypass means is formed between the side plate extending from the side surface of the condenser to the side surface of the radiator along the ventilation direction of the outside air and the side surface of the radiator. The second gap having a predetermined width is closed or opened in accordance with the required air flow rate of the radiator, or a flapper that is opened and closed to open and close in stages. The required air flow rate of the radiator is based on the amount of waste heat of the internal combustion engine. Set in stages according to the radiator required exhaust heat required for the radiator, and the Rankine cycle condenser exhaust heat exhausted by the Rankine cycle condenser is set in stages by subtracting the radiator required exhaust heat from the waste heat quantity of the internal combustion engine. It is characterized by being.

Further, in the invention of claim 2 , in claim 1 , the flapper is closed to close the second gap when the required air flow rate of the radiator exceeds a predetermined upper limit value, while the required air flow rate of the radiator is It is characterized in that the opening operation is performed to open the second gap when the predetermined lower limit value is not reached.
Furthermore, in the invention described in claim 3 , in claim 2 , a plurality of flappers are provided to independently close or open the second gaps formed on the opposite side surfaces of the radiator, and the required air flow rate of the radiator. Is less than the predetermined upper limit value and becomes an intermediate value exceeding the predetermined lower limit value, at least one of the flappers is closed, while the other one of the flappers is opened.

According to a fourth aspect of the present invention, in the third aspect , the radiator is formed by dividing the outside air into a plurality of blocks that can be received by the plurality of receiving surfaces, and each block has a third gap having a predetermined width. The bypass means further includes a second flapper that is opened and closed to close or open the third gap according to the amount of ventilation required by the radiator, and the second flapper requires a radiator. When the air flow rate is equal to or greater than the predetermined second upper limit value, the third gap is closed. On the other hand, when the radiator required air flow rate is equal to or smaller than the predetermined second lower limit value, the third gap is opened. It is characterized by being opened.

Further, the invention according to claim 5 is characterized in that, in claim 3 , the flapper is formed in different lengths capable of closing different second gaps.
Furthermore, the invention described in claim 6 is characterized in that, in any one of claims 3 to 5 , the second gap and the corresponding flapper are provided on all of the left, right, top and bottom sides of the radiator.

  According to the waste heat utilization apparatus for an internal combustion engine of the first aspect of the present invention, the bypass means allows the air flow to the condenser when the required air flow rate of the radiator, in other words, for example, when the cooling capacity required for the radiator is relatively small. It is possible to flow the outside air after bypassing the radiator, reduce the resistance of the outside air in the heat exchange unit, and increase the amount of ventilation of the condenser. Energy recovery efficiency can be improved.

The specific configuration is a radiator a second gap of a predetermined width which bypass means is formed between the side plate and the radiator side of which is extended toward the radiator side along the ventilating direction of the outside air from the side surface of the capacitor closed or open depending on the required air quantity, or Ri Do from stepwise flapper being opened and closed, the radiator required ventilation amount is stepwise according to the radiator required waste heat required for the radiator on the basis of the waste heat of the internal combustion engine The Rankine cycle condenser exhaust heat quantity exhausted by the Rankine cycle condenser is set stepwise to the heat quantity obtained by subtracting the radiator required exhaust heat quantity from the waste heat quantity of the internal combustion engine.
According to the second aspect of the invention, the flapper is closed to close the second gap when the required air flow rate of the radiator exceeds a predetermined upper limit value, while the required air flow rate of the radiator. Is performed by opening the second gap to open the second gap. Therefore, the radiator can be reduced in size by adjusting the second gap having a predetermined width, the ventilation resistance of the outside air in the heat exchange unit can be reduced, and the ventilation rate of the condenser can be effectively increased. Therefore, it is possible to improve the heat exchanging performance of the condenser and, in turn, the energy recovery efficiency of the waste heat utilization device while reducing the size of the radiator.

Furthermore, according to the invention described in claim 3 , when the required air flow rate of the radiator is less than the predetermined upper limit value and becomes an intermediate value exceeding the predetermined lower limit value, at least one of the flappers is closed. While the remaining one of the flappers is opened. This makes it possible to finely control the bypass air flow, which is the air flow that bypasses the radiator, by dividing it into at least three stages, and more effectively reducing the resistance of the outside air in the heat exchange unit according to the required air flow of the radiator. It is possible to reduce and increase the ventilation rate of the condenser more effectively, so that it is possible to further improve the heat exchange performance of the condenser and consequently the energy recovery efficiency of the waste heat utilization device.

Furthermore, according to the invention described in claim 4 , the second flapper that closes or opens the third gap between the divided blocks of the radiator has a required air flow rate of the radiator equal to or greater than a predetermined second upper limit value. Sometimes it is closed to close the third gap, while when the required air flow rate of the radiator is below a predetermined second lower limit value, it is opened to open the third gap. As a result, the bypass air flow rate of the radiator can be finely controlled by dividing it into at least four stages, and the air flow resistance of the condenser is further effectively reduced according to the required air flow rate of the radiator, and the air flow rate of the capacitor Therefore, it is possible to further increase the heat exchange performance of the condenser, and thus the energy recovery efficiency of the waste heat utilization device.

According to the invention described in claim 5 , when the flapper is formed to have different lengths capable of closing different second gaps, when the required air flow rate of the radiator becomes a predetermined intermediate value, a plurality of flappers are provided. The bypass air flow rate of the radiator can be changed depending on which of the flappers is opened. Therefore, it is possible to finely control the bypass ventilation volume in at least four stages with a simple configuration, and according to the required ventilation volume of the radiator, the ventilation resistance of the outside air in the condenser can be reduced more effectively and effectively. Therefore, the heat exchange performance of the condenser, and thus the energy recovery efficiency of the waste heat utilization device can be simplified and improved.

Further, according to the invention described in claim 6 , the maximum value of the bypass air flow rate can be effectively increased by providing the second gap and the corresponding flapper on all the left and right and upper and lower side surfaces of the radiator. In addition, since the bypass air flow rate can be widely controlled, the heat exchange performance of the condenser, and thus the energy recovery efficiency of the waste heat utilization device can be further improved.

FIG. 1 schematically shows an outline of a waste heat utilization device for an internal combustion engine according to the first embodiment. This waste heat utilization device is mounted on a vehicle, for example, and a cooling water circuit 4 for cooling the engine 2 of the vehicle, A Rankine cycle circuit (Rankine cycle) 6 (hereinafter referred to as an RC circuit) that recovers waste heat of the engine 2 is provided.
The cooling water circuit 4 forms a closed circuit by inserting an evaporator 10, a radiator 12, a thermostat 14, and a water pump 16 into a cooling water circulation path 5 extending from the engine 2 in order from the flow direction of the cooling water. doing.

The evaporator 10 exchanges heat between the cooling water that circulates in the cooling water circuit 4 and the refrigerant that circulates in the RC circuit 6, thereby using the cooling water heated by the engine 2, that is, warm water as a heat medium as waste heat of the engine 2. Is recovered by absorbing heat to the RC circuit 6 side. On the other hand, the cooling water absorbed by the refrigerant after passing through the evaporator 10 becomes warm water heated again by cooling the engine 2.
The radiator 12 is arranged in series with the evaporator 10 and further cools the cooling water that has passed through the evaporator 10 and is absorbed by the refrigerant by heat exchange with the outside air, thereby cooling the engine 2 to a desired temperature. .

  The thermostat 14 is a mechanical three-way valve that controls the amount of cooling water that is passed to the radiator 12 according to the cooling water temperature, and has two inlet ports and one outlet port. The two inlet ports are connected to a flow path 5a extending from the radiator 12 and a bypass path 5c connected to bypass the radiator 12 from the flow path 5b between the evaporator 10 and the radiator 12, respectively. As a result, the amount of cooling water passed to the radiator 12 is increased or decreased according to the cooling water temperature, and the cooling water temperature is appropriately maintained.

The water pump 16 is attached to the engine 2 and is driven according to the rotational speed of the engine 2 to circulate the cooling water in the cooling water circuit 4 appropriately.
On the other hand, the RC circuit 6 is connected to the refrigerant circulation path 7 in order from the refrigerant flow direction, the evaporator 10, the expander 20, the regenerator 22, the Rankine cycle condenser (condenser) 24 (hereinafter referred to as RC condenser), and the gas-liquid separation. The unit 26 and the refrigerant pump 28 are inserted in order to form a closed circuit.

The expander 20 is a fluid device that expands the refrigerant heated to the superheated steam state by the evaporator 10 and generates a rotational driving force. The expander 20 converts the generated rotational driving force into electric power. Thus, the generator 30 that can be used outside the waste heat utilization apparatus is mechanically connected.
The regenerator 22 is an internal heat exchanger of the RC circuit 6 that heats the refrigerant at the inlet of the evaporator 10 with the refrigerant at the outlet of the expander 20, and positively transfers the heat amount at the outlet of the expander 20 to the inlet side of the expander 20. By supplying, the recovered energy in the RC circuit 6 is increased.

The RC condenser 24 is a heat exchanger that condenses and liquefies the refrigerant that has passed through the regenerator 22.
The gas-liquid separator 26 is a receiver that separates the refrigerant condensed by the RC capacitor 24 into two layers of gas and liquid, and only the liquid refrigerant separated here flows out to the refrigerant pump 28 side.
The refrigerant pump 28 is an electric pump that is driven in accordance with a signal input to the drive unit, and the liquid refrigerant that has flowed out of the gas-liquid separator 26 is pumped to the evaporator 10 side by the refrigerant pump 28, and an RC circuit. 6 is suitably circulated.

  FIG. 2 schematically shows a longitudinal sectional view of only the front surface 32a side of the vehicle 32 on which the waste heat utilization device is mounted. The engine 2 is mounted on the lower part of the hood 32b of the vehicle 32, and the RC capacitor 24 and the radiator 12 are stacked on the front surface 32a side of the engine 2 in the front-rear direction of the vehicle 32 with a predetermined gap therebetween. Has been placed. The heat exchange unit 34 composed of the RC condenser 24 and the radiator 12 is blown by the fan 38 provided on the back side of the radiator 12 as the vehicle 32 travels.

The heat exchange unit 34 controls the ventilation amount of the air 36 that is ventilated by the fan 38 to the heat exchange unit 34, whereby the refrigerant circulating in the RC circuit 6 and the cooling water circulating in the cooling water circuit 4 Heat exchange with the outside air is suitably performed.
FIG. 3 shows an enlarged view of the heat exchange unit 34 as viewed from above. The side plate 40 extends from the left and right side surfaces 24 a of the RC condenser 24 to the left and right side surfaces 12 a of the radiator 12 along the direction of air flow 36, and then to the fan 38. , 42 are extended.

The radiator 12 is disposed with gaps (second gaps) G ₁ and G ₂ having substantially the same predetermined widths W ₁ and W ₂ between the left and right side surfaces 12a and the side plates 40 and 42, respectively. The side plates 40 and 42 are provided with flappers (bypass means) 44 and 46 for opening or closing the gaps G ₁ and G ₂ , or opening and closing them in stages.
The flappers 44 and 46 are supported by the side plates 40 and 42 by fixed ends 44a and 46a, respectively, and motors (not shown) are built in the fixed ends 44a and 46a, respectively. These motors are electrically connected to an electronic control unit (ECU) (not shown) of the vehicle 32, and the movable pieces 44b and 46b of the flappers 44 and 46 are rotated by a command from the ECU.

Specifically, the ventilation amount F required by the radiator 12 is greater than or equal to a predetermined upper limit value F _H under conditions such as when the vehicle 2 is accelerating or climbing up, or when the heat generation amount of the engine 2 is large or the outside air temperature is high. When it becomes larger, as shown in FIG. 3, the ECU closes the flappers 44 and 46 by rotating the movable pieces 44 b and 46 b in directions substantially parallel to the receiving surface 12 b of the wind 36 of the radiator 12. Then, the gaps G ₁ and G ₂ are closed, and all the air 36 after being passed through the RC condenser 24 is passed through the radiator 12 and then flows behind the heat exchange unit 34 via the fan 38. That is, the bypass air flow rate Fb, which is the air volume of the wind 38 that bypasses the radiator 12 at this time, is substantially minimized.

On the other hand, as shown in FIG. 4, when the vehicle 32 is idling, the ventilation amount F required by the radiator 12 under the condition that the heat generation amount of the engine 2 is small or the outside air temperature is low is a predetermined lower limit value F _L. When it becomes smaller below, the ECU rotates the movable pieces 44b and 46b along the side plates 40 and 42 in a direction orthogonal to the receiving surface 12b, in other words, in a direction substantially parallel to the wind 36, thereby making the flapper 44 , 46 are opened to open the gaps G ₁ , G _2, and the air 36 that has been passed through the RC condenser 24 is caused to bypass the radiator 12 and flow behind the heat exchange unit 34 via the fan 38. That is, the bypass ventilation amount Fb at this time becomes the maximum.

Furthermore, as shown in FIG. 5, when the radiator required ventilation amount F becomes a predetermined intermediate value F _M below the lower limit F _L A less than the upper limit value F _H, the gap G ₁ by opening operation of the flapper 44 while opening the, occlude the gap G ₂ a flapper 46 by closing operation. That is, the bypass air flow Fb at this time is about half of the air flow when all the flappers 44 and 46 are opened. The required air flow rate F of the radiator is estimated by the ECU based on the temperature of the cooling water circulating in the cooling water circuit 4 and the flow rate of the cooling water to the radiator 12.

  As described above, in the present embodiment, when the required air flow rate F of the radiator, in other words, when the cooling capacity required for the radiator 12 is relatively small, the air 36 that has been passed through the RC condenser 24 is bypassed by the radiator 12. Since the flow resistance of the external air in the heat exchange unit 34 can be reduced and the flow rate of the RC condenser 24 can be increased, the heat exchange performance of the RC condenser 24 and the energy recovery efficiency of the waste heat utilization device can be improved. Can be improved.

Specifically, the flappers 44 and 46 are closed to close the gaps G ₁ and G ₂ when the required air flow rate F of the radiator satisfies the condition of F ≧ F _H , while satisfying the condition of F ≦ F _L. sometimes the opening operation to open the gap _G 1, _{G 2,} further, when the radiator required ventilation amount F becomes _F L <F _{<F H} satisfying intermediate value _{F M} of the one of the flapper 44, 46 Closed operation is performed, and the other is opened. As a result, the radiator can be reduced in size by adjusting the gaps G ₁ and G ₂ , and the bypass air flow rate Fb can be finely controlled in three stages of a large flow rate, a medium flow rate, and a small flow rate. Since the ventilation resistance of the outside air in the heat exchange unit 34 can be effectively reduced and the ventilation volume of the RC condenser 24 can be increased according to the required ventilation volume F of the radiator, the RC 12 can be reduced in size while reducing the size of the radiator 12. It is possible to improve the heat exchange performance of the condenser 24, and consequently the energy recovery efficiency of the waste heat utilization device.

The present invention is not limited to the first embodiment described above, and various modifications are possible.
For example, in the case of the waste heat utilization apparatus of the second embodiment shown in FIG. 6, a heat exchange unit is provided by arranging a radiator 52 in which the wind 36 is divided into different blocks 48 and 50 that can be received by two receiving surfaces 48a and 50a. 54 is constituted. The blocks 48 and 50 are spaced apart by a gap (third gap) G ₃ having a predetermined width W _3, and in addition to the flappers 44 and 46, a flapper (second flapper) that opens or closes the gap G _3. , Bypass means) 56 is provided.

The flapper 56 is supported on the side surface of the block 50 by a fixed end 56a. Like the other flappers 44 and 46, a motor electrically connected to the ECU of the vehicle 32 is built in the fixed end 56a. The movable piece 56b of the flapper 56 is rotated by a command from the ECU.
Specifically, as shown in FIG. 6, in a range of intermediate values F _M of the radiator required ventilation amount F is described above, when equal to or less than a predetermined second lower limit value F _2L causes the opening operation of the flapper 44 Te while opening the gap G _1, the flapper 46 by the closing operation to close the gap G _2, is by further flapper 56 is the opening operation opens the gap G _3. That is, the bypass air flow rate Fb at this time is slightly larger than about half of the air volume when all the flappers 44 and 46 are opened, and can be, for example, about 2/3.

Meanwhile, although not shown, there radiator required ventilation amount F is in the range of intermediate values F _M, when a predetermined second upper limit F _2H or more, in the state of FIG. 6, flapper 56 only by closing operation by closing the gap G _3, it is also possible to suppress the bypass air amount Fb to about one third of the air volume at the time of opening operation of the entire flapper 44.
In the case of the second embodiment, the control of the bypass air flow rate Fb of the radiator 12 in the first embodiment is performed by opening the flapper 44, 46, closing the flapper 44, 46, and opening only one of the flappers 44, 46. While the operation is performed in three stages, four-stage bypass air flow rate control can be performed by opening and closing the flapper 56. Accordingly, since the bypass ventilation amount Fb of the radiator 52 can be more finely controlled according to the radiator required ventilation amount F, the ventilation resistance of the heat exchange unit 34 is further increased according to the operating state of the engine 2 and the outside air temperature. This effectively reduces the amount of ventilation of the RC condenser 24, and the heat exchange performance of the RC condenser 24, and hence the energy recovery efficiency of the waste heat utilization device, can be further improved.

On the other hand, in the case of the waste heat utilization apparatus of the third embodiment shown in FIG. 7, the radiator 12 so that the gaps G ₁ and G ₂ have different predetermined widths W ₁ and W ₂ (W ₁ > W ₂ ). The heat exchanging unit 58 is configured by arranging the movable pieces 44b and 46b of the flappers 44 and 46 to have different lengths capable of closing the gaps G ₁ and G ₂ , respectively.
In the case of the third embodiment, four stages of different bypass ventilation amounts Fb can be obtained depending on which of the flappers 44 and 46 is opened by the heat exchange unit 58. Therefore, it is a simple modification only by changing the length of the movable pieces 44a, 46b of the flappers 44, 46 by shifting the left and right arrangement of the radiator 12 in the heat exchange unit 58, compared with the case of the first embodiment. The bypass ventilation amount Fb of the radiator 12 can be controlled more finely, and the heat exchange performance of the RC condenser 24 and, consequently, the energy recovery efficiency of the waste heat utilization device can be simplified and improved.

Further, by adjusting the gaps G ₁ and G ₂ so as to open and close the flappers 44 and 46 in a plurality of stages, the bypass air flow rate Fb can be controlled more finely.
Further, in the first embodiment, the flappers 44 and 46 for closing or opening the gaps G ₁ and G ₂ are supported by the side plates 40 and 42 by the fixed ends 44a and 46a, respectively, but are shown in FIG. Like the heat exchange unit 60, the fixed ends 44a and 46a may be supported on the left and right side surfaces 12a of the radiator 12. In this case, the area of the receiving surface 12b is increased or decreased to the radiator 12 of the wind 36. The bypass ventilation amount Fb can be finely controlled.

  Further, in each of the above-described embodiments and modifications, the flappers 44 and 46 are provided only on the left and right side surfaces 12a of the radiators 12 and 52. However, the present invention is not limited to this, and a flapper is provided on the upper and lower side surfaces (not shown) of the radiator 12. It is good also as a flapper structure which consists of four flappers which can block | close and open 12 left-right and up-down. In this case, since the maximum value of the bypass ventilation amount Fb can be effectively increased and the bypass ventilation amount Fb can be controlled widely, the heat exchange performance of the RC condenser 24 and the energy of the waste heat utilization device can be reduced. Recovery efficiency can be further improved.

It is the schematic diagram which showed roughly the waste heat utilization apparatus of the internal combustion engine which concerns on 1st Embodiment of this invention. FIG. 2 is a longitudinal sectional view schematically showing only the front side of a vehicle on which the waste heat utilization apparatus of FIG. 1 is mounted. It is the figure which expanded and showed the state in case the radiator required ventilation volume of the heat exchange unit which concerns on 1st Embodiment of this invention is comparatively large. It is the figure which expanded and showed the state in case the radiator required ventilation volume of the heat exchange unit which concerns on 1st Embodiment of this invention is comparatively small. It is the figure which expanded and showed the state in case the radiator required ventilation volume of the heat exchange unit which concerns on 1st Embodiment of this invention exists in the range of an intermediate value. It is the enlarged view which showed the heat exchange unit which concerns on 2nd Embodiment of this invention. It is the enlarged view which showed the heat exchange unit which concerns on 3rd Embodiment of this invention. It is the enlarged view which showed the heat exchange unit which concerns on the modification of this invention.

Explanation of symbols

2 Engine (Internal combustion engine)
4 Cooling water circuit 6 Rankine cycle circuit (Rankine cycle)
12 Radiator 12a Side 12b Receiving surface 20 Expander 24 Rankine cycle capacitor (capacitor)
24a Side surface 34, 54, 58, 60 Heat exchange unit 40, 42 Side plate 44, 46 Flapper (bypass means)
48, 50 block 56 flapper (second flapper, bypass means)

Claims (6)

A cooling water circuit having a radiator that cools cooling water heated by waste heat of the internal combustion engine by outside air, an expander that expands the refrigerant heated by the cooling water to generate driving force, and the expansion machine circulated A waste heat utilization apparatus for an internal combustion engine, comprising a Rankine cycle condenser having a Rankine cycle condenser for condensing a refrigerant by ventilation of outside air, wherein the Rankine cycle condenser and the radiator are arranged with a predetermined gap from each other in order from the ventilation direction of the outside air. A heat exchange unit
The heat exchange unit has bypass means for flowing outside air that has been ventilated to the Rankine cycle condenser, bypassing the radiator,
The bypass means includes a second gap having a predetermined width formed between a side plate extending from a side surface of the Rankine cycle condenser to a side surface of the radiator along a ventilation direction of outside air and a side surface of the radiator. It consists of a flapper that is closed or opened according to the required ventilation volume of the radiator, or opened and closed to open and close in stages,
The required air flow rate of the radiator is set in a stepwise manner according to the radiator required exhaust heat amount required for the radiator based on the waste heat amount of the internal combustion engine, and the Rankine cycle capacitor exhaust heat amount exhausted by the Rankine cycle capacitor is A waste heat utilization apparatus for an internal combustion engine, wherein the waste heat utilization apparatus for the internal combustion engine is set in a stepwise manner by subtracting the radiator required exhaust heat amount from the waste heat amount of the internal combustion engine. The flapper is closed to close the second gap when the required amount of ventilation of the radiator is equal to or greater than a predetermined upper limit value, while the second flapper is closed when the required amount of ventilation of the radiator is equal to or less than a predetermined lower limit value. The waste heat utilization apparatus for an internal combustion engine according to claim 1 , wherein the apparatus is operated to open the gap. A plurality of the flappers are provided to independently close or open the second gaps formed on the opposing side surfaces of the radiator, and the required air flow rate of the radiator is less than a predetermined upper limit value. 3. The waste heat of the internal combustion engine according to claim 2 , wherein when the intermediate value exceeds the lower limit value, at least one of the flappers is closed, and the other one of the flappers is opened. Use device. The radiator is formed by dividing outside air into a plurality of blocks that can be received by a plurality of receiving surfaces, and each block is spaced apart by a third gap having a predetermined width,
The bypass means further includes a second flapper that is opened and closed to close or open the third gap in accordance with the amount of ventilation required by the radiator,
The second flapper is closed to close the third gap when the required air flow rate of the radiator is equal to or greater than a predetermined second upper limit value, while the required air flow rate of the radiator is equal to or less than the predetermined second lower limit value. 4. The waste heat utilization apparatus for an internal combustion engine according to claim 3 , wherein the opening operation is performed to open the third gap. The waste heat utilization apparatus for an internal combustion engine according to claim 3 , wherein the flapper is formed to have different lengths capable of closing different second gaps. The waste heat utilization apparatus for an internal combustion engine according to any one of claims 3 to 5 , wherein the second gap and the flapper corresponding to the second gap are provided on all left and right and upper and lower side surfaces of the radiator.

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