JP2022152076A - Co2 separation device of internal combustion engine - Google Patents

Abstract

To provide a CO2 separation device of an internal combustion engine that can perform adsorption/desorption of CO2 with a CO2 adsorbent excellently and rapidly by controlling the CO2 adsorbent to an appropriately low temperature state during adsorption of CO2 and increasing the temperature of the CO2 adsorbent rapidly during desorption of CO2.SOLUTION: A CO2 separation device comprises: a heat exchanger 6 that absorbs the heat of exhaust gas by exchanging heat with the exhaust gas; a CO2 adsorbent (7) arranged on the downstream side with respect to the heat exchanger 6 in an exhaust passage 4, and having characteristics of adsorbing CO2 in the exhaust gas at low temperature and desorbing it at high temperature; a bypass passage 13 branching from the upstream side with respect to the heat exchanger 6 in the exhaust passage 4 and passing through the CO2 adsorbent; and first and second on-off valves 15, 16 that switch the flow of the exhaust gas to the exhaust passage 4 side or to the bypass passage 13 side, where the on-off valves switch the flow of the exhaust gas to the exhaust passage 4 side during CO2 adsorption control, and to the bypass passage 13 side during CO2 desorption control (Figs.8 and 9).SELECTED DRAWING: Figure 1

Description

The present invention relates to a CO2 separation device for an internal combustion engine that separates CO2 from the exhaust gas of the internal combustion engine.

CO2 (carbon dioxide) contained in the exhaust gas of internal combustion engines installed in automobiles is said to be one of the causes of global warming. A reduction in the amount is required.

2. Description of the Related Art Conventionally, a CO2 separation device for separating CO2 from exhaust gas is known, and is disclosed in Patent Document 1, for example. This CO2 separation device includes an exhaust gas supply source, two adsorption units (adsorption units) each containing a CO2 adsorbent for adsorbing CO2 in the exhaust gas, a hydrogen supply source, and a supply of hydrogen to the two adsorption units. A switching means for switching the supply of exhaust gas and hydrogen is provided. The CO2 adsorbent is composed of zeolite, silica gel, or the like, which has CO2 absorption performance.

In this CO2 separation device, the switching means allows hydrogen to be supplied from the hydrogen supply source to the other adsorption section while the exhaust gas is being supplied from the exhaust gas supply source to the other adsorption section. In one adsorption part, the CO2 in the inflowing exhaust gas is adsorbed by the CO2 adsorbent, and in the other adsorption part, the CO2 already adsorbed by the CO2 adsorbent is desorbed by the inflowing hydrogen and mixed with the hydrogen. be. By alternately repeating such adsorption/desorption operations between the two adsorption units, CO2 is separated from the exhaust gas.

JP 2020-164424 A

The adsorption performance of the CO2 adsorbent made of zeolite or the like as described above changes according to the temperature, and exhibits temperature characteristics such that the lower the adsorbent temperature, the higher the adsorption performance, and the higher the adsorbent temperature, the lower the adsorption performance. On the other hand, in the conventional CO2 separation device, regardless of the temperature state of the exhaust gas and the CO2 adsorbent, the inflowing exhaust gas is used as it is to perform CO2 adsorption and desorption operations. Therefore, when high-temperature exhaust gas is discharged from the internal combustion engine, the CO2 adsorbent becomes in a high temperature state, and CO2 cannot be adsorbed satisfactorily. In addition, two separate adsorption units (adsorption units) for accommodating the CO2 adsorbent must be provided, which may hinder downsizing of the apparatus.

The present invention has been made in order to solve such problems. It is an object of the present invention to provide a CO2 separation device for an internal combustion engine that can adsorb/desorb CO2 satisfactorily and quickly with a CO2 adsorbent.

In order to achieve this object, a CO2 separation device for an internal combustion engine that separates CO2 from exhaust gas of an internal combustion engine is provided in an exhaust passage 4, and heat exchange with the exhaust gas flowing through the exhaust passage 4 causes exhaust gas and a CO2 adsorbent ( The CO2 adsorber 7 in the embodiment (hereinafter the same in this section) and the exhaust passage 4 branch from the upstream side of the heat exchanger 6, pass through the CO2 adsorbent, and are open to the atmosphere on the downstream side of the CO2 adsorbent. switching means (first and second on-off valves 15 and 16) for switching the flow of exhaust gas to either the side of the exhaust passage 4 or the side of the bypass passage 13; By selectively executing CO2 adsorption control for adsorbing to the material and CO2 desorption control for desorbing CO2 adsorbed by the CO2 adsorbent, the switching means is controlled so that when CO2 adsorption control is performed, the exhaust and control means (ECU 2, FIGS. 6 and 7) for switching the gas flow to the exhaust passage 4 side and switching the exhaust gas flow to the bypass passage 13 side when CO2 desorption control is executed. and

In this CO2 separation device for an internal combustion engine, a heat exchanger and a CO2 adsorbent are provided in the exhaust passage in this order from the upstream side, and the CO2 adsorbent adsorbs CO2 in the exhaust gas at low temperatures and desorbs it at high temperatures. have characteristics. In addition, a bypass passage is provided that branches from the upstream side of the heat exchanger of the exhaust passage and passes through the CO2 adsorbent. Switch to the aisle side. In this CO2 separation device, CO2 adsorption control for adsorbing CO2 in the exhaust gas to the CO2 adsorbent and CO2 desorption control for desorbing CO2 adsorbed on the CO2 adsorbent are selectively executed.

When executing the CO2 adsorption control, the exhaust gas flow is switched to the exhaust passage side. As a result, the high-temperature exhaust gas first passes through the heat exchanger, loses heat through heat exchange, is cooled, and then flows into the CO2 adsorbent. As a result, the CO2 adsorbent is cooled by the exhaust gas and controlled to an appropriate low temperature state, so that the CO2 adsorption by the CO2 adsorbent can be carried out satisfactorily.

On the other hand, when executing the CO2 desorption control, the exhaust gas flow is switched to the bypass passage side. As a result, the hot exhaust gas does not pass through the heat exchanger and directly flows into the CO2 adsorbent via the bypass passage. As a result, the temperature of the CO2 adsorbent is rapidly raised by the high-temperature exhaust gas without being affected by the heat mass of the heat exchanger, so that CO2 can be desorbed from the CO2 adsorbent satisfactorily and quickly. can. In addition, unlike conventional devices, CO2 adsorption/desorption operations can be performed using a single adsorbent unit containing a CO2 adsorbent, thereby miniaturizing the device. can be done.

The invention according to claim 2 is the CO2 separation apparatus for an internal combustion engine according to claim 1, further comprising cooling means (water pump 11) for cooling the heat exchanger 6, and the control means executes CO2 adsorption control. At this time, the flow of the exhaust gas is switched to the side of the exhaust passage 4, and cooling control is performed to control the cooling of the heat exchanger 6 by the cooling means (steps 11, 12, 15 to 17 in FIG. 5). .

According to this configuration, by controlling the cooling of the heat exchanger by the cooling means during the CO2 adsorption control, the temperature of the heat-exchanged exhaust gas is adjusted to a temperature suitable for the CO2 adsorption of the CO2 adsorbent. can be controlled, and the adsorption of CO2 can be performed even better.

The invention according to claim 3 is the CO2 separation device for an internal combustion engine according to claim 2, wherein temperature parameter detection means (second exhaust temperature Tgas2) for detecting a temperature parameter (second exhaust temperature Tgas2) representing the temperature of the CO2 adsorbent It further comprises a sensor 22), and the control means is characterized by performing a cooling control based on the detected temperature parameter (steps 16, 17 in FIG. 5, FIG. 6).

According to this configuration, the cooling control of the heat exchanger is performed based on the detected temperature parameter representing the actual temperature of the CO2 adsorbent. It can be controlled to be in a state, and the maximum amount of CO2 can be adsorbed.

The invention according to claim 4 is the CO2 separation device for an internal combustion engine according to claim 1, wherein the exhaust passage 4 is open to the atmosphere at the downstream end thereof, and has a branch passage 10 branched from the downstream side of the CO2 adsorbent. A storage tank 9 provided in the branch passage 10 for storing CO2 desorbed from the CO2 adsorbent, and a flow of exhaust gas downstream of the CO2 adsorbent to the exhaust passage 6 side or branch a second switching means (switching valve 12) for switching to either the passage 10 side, and the control means switches the flow of the exhaust gas to the bypass passage 13 side by the switching means when executing the CO2 desorption control. It is characterized by switching to the branch passage 10 side by the second switching means (steps 21 to 23 in FIG. 7).

According to this configuration, during the CO2 desorption control, the high-temperature exhaust gas is allowed to flow directly into the CO2 adsorbent through the bypass passage, thereby desorbing CO2 from the CO2 adsorbent satisfactorily. The desorbed CO2 can be directed to a storage tank via a branch channel and stored.

The invention according to claim 5 is the CO2 separation device for an internal combustion engine according to claim 2, wherein the CO2 concentration detection means (CO2 concentration sensor 23) detects the CO2 concentration CCO2 downstream of the CO2 adsorbent in the exhaust passage 4. and the control means switches to CO2 desorption control when the detected CO2 concentration CCO2 becomes equal to or higher than a predetermined value CREF during CO2 adsorption control (FIG. 4).

According to this configuration, when the detected CO2 concentration CCO2 becomes equal to or higher than the predetermined value CREF during CO2 adsorption control, it is determined that the CO2 adsorbent is saturated with CO2, and control is switched to CO2 desorption control. As a result, switching from CO2 adsorption control to CO2 desorption control can be performed at the optimum timing when the CO2 adsorbent becomes saturated with CO2, thereby maximizing CO2 adsorption/desorption. be able to.

1 is a diagram schematically showing a CO2 separation device to which the present invention is applied together with an internal combustion engine; FIG. It is a block diagram showing the configuration of the control system of the CO2 separation device. FIG. 3 is a diagram showing temperature characteristics of adsorption performance of a CO2 adsorbent; 4 is a flowchart showing a main flow of a CO2 adsorption/desorption control process; FIG. 5 is a flow chart showing processing of adsorption mode control in FIG. 4 ; FIG. It is a map for setting the target rotation speed of the water pump. FIG. 5 is a flow chart showing the desorption mode control process of FIG. 4; FIG. FIG. 4 is a diagram showing the operation of the CO2 separator obtained by adsorption mode control; FIG. 4 is a diagram showing the operation of the CO2 separator obtained by desorption mode control;

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a CO2 separation device 1 according to this embodiment together with an internal combustion engine 3 .

An internal combustion engine (hereinafter referred to as "engine") 3 is, for example, a gasoline engine mounted on a vehicle (not shown) as a power source. An intake passage (not shown) and an exhaust passage 4 are connected to the engine 3 . In the engine 3, in each cylinder (not shown), a mixture of fuel injected from a fuel injection valve (not shown) and air taken in from an intake passage is ignited by a spark plug (not shown). High-temperature combustion gas generated by combustion is discharged to the exhaust passage 4 as exhaust gas. The exhaust passage 4 is open to the atmosphere via a one-way valve 5 at its downstream end.

The CO2 separation device 1 is for separating and recovering CO2 (carbon dioxide) from the exhaust gas flowing through the exhaust passage 4, and includes a heat exchanger 6, a CO2 adsorber 7, a compressor 8 and a storage tank 9. ing. The heat exchanger 6 and the CO2 adsorber 7 are provided in the exhaust passage 4 in this order from the upstream side, and the compressor 8 and the storage tank 9 are connected to the branch passage 10 that branches from the downstream side of the CO2 adsorber 7 in the exhaust passage 4. is provided.

The heat exchanger 6 functions as a water-cooled cooler that cools the exhaust gas by exchanging heat between the cooling water flowing through the cooling water circuit 6a and the high-temperature exhaust gas flowing through the exhaust passage 4 . An electric water pump 11 is provided in the cooling water circuit 6a. As shown in FIG. 2, the water pump 11 is electrically connected to an ECU (Electronic Control Unit) 2. By controlling the rotation speed NEWP of the water pump 11 with the ECU 2, the flow rate of cooling water is controlled. The degree of cooling of the exhaust gas is thereby controlled.

The CO2 adsorber 7 adsorbs/desorbs CO2 from the exhaust gas, and contains a CO2 adsorbent (not shown) for that purpose. The CO2 adsorbent is provided so as to be exposed to exhaust gas flowing through the CO2 adsorber 7 . Also, the CO2 adsorbent is composed of, for example, lithium composite oxide or zeolite, and has adsorption performance depending on temperature as shown in FIG.

Specifically, the CO2 adsorption amount QCO2 that can be adsorbed by the CO2 adsorbent changes according to the adsorbent temperature (the temperature of the CO2 adsorbent) Tads. It decreases as Tads increases. Therefore, as shown in the figure, the CO2 adsorption amount QCO2 when the adsorbent temperature Tads is a first temperature T1 on the low temperature side and a second temperature T2 on the high temperature side is expressed as a first adsorption amount Q1 and a second adsorption amount Q2, respectively. In this case, after CO2 is adsorbed while the adsorbent temperature Tads is at the first temperature T1, when the adsorbent temperature Tads is raised to the second temperature T2, the difference between the first and second adsorption amounts Q1 and Q2 ( =Q1-Q2), an amount ΔQCO2 of CO2 is desorbed and recovered.

The compressor 8 is composed of, for example, an electric pump, and compresses the CO2 that has been desorbed from the CO2 adsorbent and stored in the storage tank 9 . Driving/stopping of the compressor 8 is controlled by the ECU 2 .

A switching valve 12 is provided at a branching portion between the exhaust passage 4 and the branching passage 10 . The switching valve 12 switches the flow of the exhaust gas on the downstream side of the CO2 adsorber 7 to either the branch passage 10 side (storage side) or the exhaust passage 4 side (atmosphere side). The operation of this switching valve 12 is controlled by the ECU 2 .

The CO2 separator 1 further comprises a bypass passage 13 . The bypass passage 13 is for supplying hot exhaust gas directly to the CO2 adsorber 7 . The bypass passage 13 branches from the exhaust passage 4 so as to bypass the heat exchanger 6, passes through the CO2 adsorber 7, does not intersect the exhaust passage 4, and is located downstream thereof via a one-way valve 14. open to the atmosphere.

A first on-off valve 15 for opening and closing the exhaust passage 4 is provided between the heat exchanger 6 and the CO2 adsorber 7 in the exhaust passage 4, and a second on-off valve for opening and closing the exhaust passage 4 is provided in the bypass passage 13. 16 are provided. With the above configuration, the high-temperature exhaust gas discharged from the engine 3 is cooled by the heat exchanger 6 and then supplied to the CO2 adsorber 7 when the first on-off valve 15 is open. When the two on-off valve 16 is open, the CO2 is directly supplied to the CO2 adsorber 7 . The opening and closing of these first and second on-off valves 15 and 16 are controlled by the ECU 2 .

The exhaust passage 4 is provided with a first exhaust temperature sensor 21 upstream of the branch of the bypass passage 13, and a second exhaust temperature sensor 22 and a CO2 concentration sensor 23 are provided downstream of the CO2 adsorber 7. It is The first and second exhaust temperature sensors 21 and 22 detect the exhaust gas temperature at each position as a first exhaust temperature Tgas1 and a second exhaust temperature Tgas2, respectively. The CO2 concentration sensor 23 detects the CO2 concentration CCO2 of exhaust gas downstream of the CO2 adsorber 7 . Those detection signals are output to the ECU 2 .

The ECU 2 is composed of a microcomputer including a CPU, RAM, ROM, and I/O interface (none of which are shown). The ECU 2 executes CO2 adsorption/desorption control for controlling the adsorption and desorption of CO2 by the CO2 separation device according to the detection signals of the sensors 21-23. In this embodiment, the ECU 2 constitutes control means.

FIG. 4 shows the main flow of the CO2 adsorption/desorption control process described above. This process is executed at predetermined time intervals while the engine 3 is in a normal operating state. In this process, first, in step 1 (illustrated as "S1"; the same shall apply hereinafter), it is determined whether or not the detected CO2 concentration CCO2 is smaller than a predetermined value CREF.

When the determination result is YES and the CO2 concentration CCO2 is smaller than the predetermined value CREF, the process proceeds to step 2, and adsorption mode control is executed to cause the CO2 adsorbent to adsorb CO2. On the other hand, when the determination result in step 1 is NO and the CO2 concentration CCO2 is equal to or higher than the predetermined value CREF, it is assumed that the CO2 adsorbed by the CO2 adsorbent has reached a saturated state, and the process proceeds to step 3 to remove CO2 from the CO2 adsorbent. Execute desorption mode control for desorption.

The adsorption mode control described above is executed by the processing in FIG. In this adsorption mode control, the first on-off valve 15 is opened (step 11), and at the same time, the second on-off valve 16 is closed (step 12). Further, the switching valve 12 is switched to the atmosphere side (exhaust passage 4 side) (step 13), and the compressor 8 is stopped (step 14).

By the above control, as indicated by the thick line in FIG. 8, the high-temperature exhaust gas discharged from the engine 3 is sent to the heat exchanger 6 side by opening the first on-off valve 15, and cooled. After being cooled by heat exchange with water, it flows into the CO2 adsorber 7 . As a result, the CO2 adsorbent in the CO2 adsorber 7 is controlled to be in a low temperature state, so that the CO2 in the exhaust gas is favorably adsorbed by the CO2 adsorbent. On the other hand, the remaining components such as N 2 in the exhaust gas flow out from the CO 2 adsorber 7 and are released to the atmosphere via the switching valve 12 and the one-way valve 5 .

Further, by driving the water pump 11 (step 15), the cooling water is circulated and the flow rate of the cooling water is controlled. Specifically, in step 16, the difference (=Tgas2-Tgas_CMD) between the second exhaust temperature Tgas2 detected by the second exhaust temperature sensor 22 and its predetermined target value Tgas_CMD is calculated as the temperature deviation ΔTgas.

Next, in step 17, the target rotation speed NEWP_CMD of the water pump 11 is calculated by searching the map of FIG. 6 according to the temperature deviation ΔTgas, and this processing is terminated. In this map, the target engine speed NEWP_CMD is set to a predetermined value N1 when the temperature deviation ΔTgas is 0 or less, that is, when the second exhaust gas temperature Tgas2 is less than the target value Tgas_CMD.

On the other hand, when the temperature deviation ΔTgas is greater than 0, that is, when the second exhaust gas temperature Tgas2 is higher than the target value Tgas_CMD, the target engine speed NEWP_CMD is set to a larger value as the temperature deviation ΔTgas increases. As a result, the larger the temperature deviation ΔTgas, the more the amount of cooling water in the heat exchanger 6 is increased, so that the temperature of the CO2 adsorbent is appropriately controlled.

Next, the desorption mode control process executed in step 3 of FIG. 4 will be described with reference to FIG. The content of this desorption mode control is basically the opposite of the above-described adsorption mode control. ). In addition, the switching valve 12 is switched to the storage side (the branch passage 10 side) (step 23), the compressor 8 is driven (step 24), the water pump 11 is stopped (step 25), and this processing ends.

Due to the above control, as indicated by the thick line in FIG. 9, high-temperature exhaust gas from the engine 3 directly flows into the CO2 adsorber 7 via the opened second on-off valve 16 and the bypass passage 13 . As a result, the temperature of the CO2 adsorbent in the CO2 adsorber 7 is raised by the exhaust gas, and the CO2 adsorbed on the CO2 adsorbent is desorbed. Exhaust gas flows out of the CO2 adsorber 7 and is released to the atmosphere via the one-way valve 14 . On the other hand, the desorbed CO 2 flows to the branch passage 10 side through the switching valve 12 and is stored in the storage tank 9 in a state of being compressed by the compressor 8 .

As described above, according to the present embodiment, during CO2 adsorption control, the flow of the exhaust gas is switched to the exhaust passage 4 side by the first and second on-off valves 15 and 16, so that the high-temperature exhaust gas is heated. After being cooled by heat exchange with cooling water in the exchanger 6 , it flows into the CO 2 adsorber 7 . As a result, the CO2 adsorbent is cooled by the exhaust gas and controlled to an appropriate low temperature state, so that the CO2 adsorption by the CO2 adsorbent can be carried out satisfactorily.

On the other hand, during the CO2 desorption control, the flow of the exhaust gas is switched to the bypass passage 13 side by the first and second on-off valves 15 and 16, so that the high-temperature exhaust gas does not pass through the heat exchanger 6 and passes through the bypass passage. Via 12 it flows directly into the CO2 adsorber 7 . As a result, the temperature of the CO2 adsorbent is rapidly raised by the high-temperature exhaust gas without being affected by the heat mass of the heat exchanger 6, so that CO2 can be desorbed from the CO2 adsorbent satisfactorily and quickly. can be done. In addition, unlike the conventional device, the CO2 adsorption/desorption operation can be performed using a single adsorbent unit containing the CO2 adsorbent, thereby making it possible to reduce the size of the device. .

Further, the second exhaust temperature Tgas2 (exhaust gas temperature on the downstream side of the CO2 adsorber 7) is used as a temperature parameter representing the temperature of the CO2 adsorbent, and the detected second exhaust temperature Tgas2 is set to the target value Tgas_CMD. , the target rotation speed NEWP_CMD of the water pump 11 is set, and the flow rate of the cooling water of the heat exchanger 6 is controlled (steps 16 and 17 in FIG. 5, FIG. 6). As a result, the temperature of the CO2 adsorbent can be controlled so as to be in an optimal temperature state for CO2 adsorption, and the maximum CO2 adsorption can be achieved.

Furthermore, during CO2 desorption control, by switching the switching valve 12 to the branch passage 10 side, the desorbed CO2 can be guided to the compressor 8 and stored in the storage tank 9 .

During CO2 adsorption control, when the detected CO2 concentration CCO2 on the downstream side of the CO2 adsorbent reaches or exceeds a predetermined value CREF, it is determined that the CO2 adsorbent is saturated with CO2, and the control is switched to CO2 desorption control. (Steps 1 and 3 in FIG. 4). As a result, switching to CO2 desorption control can be performed at the optimum timing when the CO2 adsorbent becomes saturated with CO2, and adsorption/desorption of CO2 can be performed to the maximum extent.

It should be noted that the present invention is not limited to the described embodiments and can be implemented in various ways. For example, in the embodiment, the second exhaust temperature Tgas2 (exhaust gas temperature on the downstream side of the CO2 adsorber 7) is used as the temperature parameter representing the temperature of the CO2 adsorbent. The temperature of the exhaust gas at the position, for example, the first exhaust temperature Tgas1 (exhaust gas temperature immediately downstream of the engine 3) in the embodiment may be used, or an average value thereof may be used. Of course, it is also possible to directly detect the temperature of the CO2 adsorbent.

Further, in the embodiment, a single predetermined value CREF is used as the threshold value of the CO2 concentration CCO2 for determining switching between CO2 adsorption control (adsorption mode control) and CO2 desorption control (desorption mode control). However, the hysteresis may be set by setting different values depending on the switching direction of both controls. Furthermore, in the embodiment, the target value Tgas_CMD of the second exhaust gas temperature Tgas2 is a predetermined value, but it may be changed according to the operating state of the engine 3 or the like.

Also, the embodiment is an example using one heat exchanger 6 and one CO2 adsorber 7, but it is also within the scope of the present invention to use two or more. Furthermore, in the embodiment, switching between the exhaust passage 4 and the bypass passage 13 is performed by interlocking opening and closing of the first and second on-off valves 15 and 16 provided in both passages 4 and 13. A single switching valve such as the switching valve 12 may be provided at the branches of 4 and 13 .

Further, the embodiment is an example in which the present invention is applied to a gasoline engine mounted on a vehicle, but the present invention is not limited to this, and may be applied to other types of engines such as diesel engines. It is also applicable to engines other than vehicles. In addition, it is possible to change the detailed configuration as appropriate within the scope of the present invention.

1 CO2 separation device 2 ECU (control means)
3 Engine (internal combustion engine)
4 exhaust passage 6 heat exchanger 7 CO2 adsorber (CO2 adsorbent)
9 storage tank 10 branch passage 11 water pump (cooling means)
12 switching valve (second switching means)
13 Bypass passage 15 First on-off valve (switching means)
16 Second on-off valve (switching means)
21 first exhaust temperature sensor 21 (temperature parameter detection means)
22 second exhaust temperature sensor 22 (temperature parameter detection means)
23 CO2 concentration sensor (CO2 concentration detection means)
Tgas1 First exhaust temperature (temperature parameter)
Tgas2 Second exhaust temperature (temperature parameter)
CCO2 CO2 concentration CREF Predetermined value

Claims (5)

A CO2 separation device for an internal combustion engine that separates CO2 from an exhaust gas of the internal combustion engine,
a heat exchanger that is provided in an exhaust passage of the internal combustion engine and absorbs heat of the exhaust gas by heat exchange with the exhaust gas flowing through the exhaust passage;
a CO2 adsorbent disposed downstream of the heat exchanger in the exhaust passage and having the property of adsorbing CO2 in exhaust gas at low temperatures and desorbing CO2 at high temperatures;
a bypass passage that branches from the upstream side of the heat exchanger of the exhaust passage, passes through the CO2 adsorbent, and is open to the atmosphere on the downstream side of the CO2 adsorbent;
switching means for switching the flow of exhaust gas to either the exhaust passage side or the bypass passage side;
By selectively executing CO2 adsorption control for causing the CO2 in the exhaust gas to be adsorbed by the CO2 adsorbent and CO2 desorption control for desorbing the CO2 adsorbed by the CO2 adsorbent, and by controlling the switching means a control means for switching the exhaust gas flow to the exhaust passage side when executing the CO2 adsorption control, and switching the exhaust gas flow to the bypass passage side when executing the CO2 desorption control;
A CO2 separation device for an internal combustion engine, comprising: Further comprising cooling means for cooling the heat exchanger,
The control means is characterized in that when executing the CO2 adsorption control, the flow of the exhaust gas is switched to the exhaust passage side, and cooling control is executed to control the cooling of the heat exchanger by the cooling means. The CO2 separation device for an internal combustion engine according to claim 1. further comprising temperature parameter detection means for detecting a temperature parameter representing the temperature of the CO2 adsorbent;
3. The CO2 separation device for an internal combustion engine according to claim 2, wherein said control means executes said cooling control based on said detected temperature parameter. The exhaust passage has a branch passage that is open to the atmosphere at a downstream end and branches from the downstream side of the CO2 adsorbent,
a storage tank provided in the branch passage for storing CO2 desorbed from the CO2 adsorbent;
a second switching means for switching the flow of exhaust gas on the downstream side of the CO2 adsorbent to either the exhaust passage side or the branch passage side;
When executing the CO2 desorption control, the control means switches the flow of the exhaust gas to the bypass passage side by the switching means and switches the flow of the exhaust gas to the branch passage side by the second switching means. The CO2 separation device for an internal combustion engine according to claim 1. further comprising CO2 concentration detection means for detecting the CO2 concentration downstream of the CO2 adsorbent in the exhaust passage;
3. The CO2 of the internal combustion engine according to claim 2, wherein the control means switches to the CO2 desorption control when the detected CO2 concentration becomes equal to or higher than a predetermined value during the CO2 adsorption control. separation device.

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