Co2 separation device for internal combustion engines

Abstract

The present application provides a CO2 separation device for an internal combustion engine, which can perform adsorption / desorption of CO2 by a CO2 adsorption material well by maintaining the temperature of exhaust gas supplied to the CO2 adsorption material at an appropriate temperature. Further, the present application provides a CO2 separation device for an internal combustion engine, which can prevent overheating of the CO2 adsorption material even in the case where the temperature of the exhaust gas excessively rises. To achieve the above, the CO2 separation device for an internal combustion engine of the present application is a CO2 separation device for an internal combustion engine which is provided in an exhaust system of an internal combustion engine and separates CO2 from exhaust gas, and which includes: an exhaust passage which is connected to the internal combustion engine, through which the exhaust gas flows; a CO2 adsorption material which is provided in the exhaust passage, which adsorbs CO2 in the exhaust gas at a given low temperature, and which causes the adsorbed CO2 to desorb at a given high temperature; and a heat discharge controller which is provided on the upstream side of the CO2 adsorption material in the exhaust passage, which is introduced with the exhaust gas, and which absorbs heat of the exhaust gas by heat exchange with the exhaust gas.

Description

TECHNICAL FIELD

[0001] The present application relates to a CO2 separation device of an internal combustion engine, which is provided in an exhaust system of the internal combustion engine to separate CO2 from exhaust gas. BACKGROUND

[0002] In order to reduce adverse effects on the earth's environment, exhaust gas regulations for automobiles are further developed. In particular, CO2 (carbon dioxide) contained in exhaust gas of an internal combustion engine is considered to be a cause of global warming, and separation and recovery of CO2 from exhaust gas is required to reduce the amount of CO2 emitted from automobiles.

[0003] In the past, as a CO2 separation device that separates CO2 from exhaust gas, a device described in Patent Literature 1 is known. In this CO2 separation device, a CO2 capture material that captures CO2 is provided in an exhaust passage of an internal combustion engine, and CO2 in exhaust gas of the internal combustion engine is captured by the CO2 capture material, and the captured CO2 is desorbed from the CO2 capture material. As the CO2 capture material, zeolite or the like is used.

[0004] Specifically, the exhaust passage has two branch passages that can flow exhaust gas from only one side by a switching valve, and a CO2 capture material is provided in each of the two branch passages. By flowing exhaust gas in one of the branch passages, CO2 in the exhaust gas is captured by the CO2 capture material of the branch passage (capture step), and the CO2 captured by the CO2 capture material is desorbed by warming the CO2 capture material of the other branch passage by the heat of the exhaust gas (desorption step). Further, in each of the CO2 capture materials, the capture step and the desorption step described above are alternately repeated, whereby CO2 is separated from the exhaust gas.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: International Publication No. 2016 / 076041 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] Among the materials used as the CO2 adsorption material, such as the zeolite described above, the CO2 adsorption performance varies depending on the temperature thereof, showing a temperature characteristic in which the lower the temperature of the adsorption material, the higher the CO2 adsorption performance, and the CO2 adsorption performance decreases as the temperature of the adsorption material increases. Therefore, in a CO2 separation device that separates and recovers CO2 in exhaust gas by switching the adsorption / desorption of CO2 by changing the temperature of the CO2 adsorption material, in order to maximize the effective use of the CO2 adsorption performance of the CO2 adsorption material, it is necessary to appropriately control the temperature state of the CO2 adsorption material so that it becomes a low temperature suitable for adsorption at the time of adsorption of CO2 and a high temperature suitable for desorption at the time of desorption of CO2.

[0010] In particular, in the case of a system that uses the exhaust heat (heat of exhaust gas) of an internal combustion engine for the temperature increase of the CO2 adsorption material at the time of desorption, since the temperature of the exhaust gas can greatly vary depending on the operating state, load, or external environment of the internal combustion engine, or the like, it is desirable to appropriately adjust the temperature of the exhaust gas supplied to the CO2 adsorption material regardless of such variation in the temperature of the exhaust gas, so that the CO2 adsorption material supplied with the exhaust gas is maintained at a temperature suitable for the adsorption / desorption of CO2.

[0011] Further, generally, the CO2 adsorption material is irreversibly deteriorated or damaged by being continuously exposed to a high temperature that greatly exceeds the appropriate temperature at the time of desorption of CO2. Therefore, in the case where the temperature of the exhaust gas is such a high temperature, it is more desirable to protect the CO2 adsorption material by limiting the supply of the exhaust gas to the CO2 adsorption material, or the like.

[0012] The present application is made to solve such a problem, and aims to provide a CO2 separation device for an internal combustion engine that can appropriately perform the adsorption / desorption of CO2 by the CO2 adsorption material by maintaining the temperature of the exhaust gas supplied to the CO2 adsorption material at an appropriate temperature. Further, the present application aims to provide a CO2 separation device for an internal combustion engine that can prevent overheating of the CO2 adsorption material in the case where the temperature of the exhaust gas excessively increases.

[0013] Means for solving the problem

[0014] To achieve the object, the CO2 separation device for internal combustion engine according to the technical solution 1 of the present application is a CO2 separation device 1 for internal combustion engine provided in an exhaust system of an internal combustion engine (engine 3 in the embodiment (hereinafter the same as in the technical solution)) and separating CO2 from exhaust gas, characterized by comprising: an exhaust passage 4 connected to the internal combustion engine for exhaust gas to flow; a CO2 adsorption material provided in the exhaust passage, adsorbing CO2 in the exhaust gas at a given low temperature, and desorbing the adsorbed CO2 at a given high temperature; and a heat removal controller (heat exchange structure 61) provided on the upstream side of the CO2 adsorption material in the exhaust passage, introduced into the exhaust gas, and absorbing heat of the exhaust gas by heat exchange with the exhaust gas.

[0015] In the CO2 separation device for internal combustion engine, since the CO2 adsorption material that repeats adsorption and desorption of CO2 according to the change in temperature state is provided in the exhaust passage, CO2 in the exhaust gas is adsorbed by the CO2 adsorption material that is warmed to a given high temperature state by the exhaust gas of high temperature introduced into the CO2 adsorption material through the exhaust passage, and the CO2 adsorbed before that is desorbed from the CO2 adsorption material that becomes a given low temperature state by losing heat.

[0016] Further, according to the CO2 separation device for internal combustion engine, heat exchange with the exhaust gas is performed by the heat removal controller provided on the upstream side of the CO2 adsorption material in the exhaust passage, thereby absorbing heat of the exhaust gas before being introduced into the CO2 adsorption material. Thus, the temperature of the exhaust gas supplied to the CO2 adsorption material can be maintained at an appropriate temperature, and adsorption / desorption of CO2 by the CO2 adsorption material can be performed well.

[0017] The invention according to the technical solution 2 is characterized in that, in the CO2 separation device for internal combustion engine described in the technical solution 1, an exhaust gas temperature detection unit (exhaust gas temperature sensor 15) is provided on the downstream side of the heat removal controller and on the upstream side of the CO2 adsorption material in the exhaust passage, detects the temperature of the exhaust gas flowing into the CO2 adsorption material as an exhaust gas temperature Tgas, a first bypass passage 63 is branched from the upstream side of the heat removal controller in the exhaust passage, merges with the upstream side of the exhaust gas temperature detection unit while bypassing the heat removal controller, and a first flow control unit (first flow control valve 65, ECU 2, Figure 5 ) controls the flow rate of the exhaust gas flowing in the first bypass passage according to the detected exhaust gas temperature in order to adjust the exhaust gas temperature.

[0018] According to this structure, in addition to the adjustment of the exhaust gas temperature by the heat recovery controller, the flow rate of the exhaust gas flowing in the first bypass passage that bypasses the heat recovery controller is controlled in accordance with the exhaust gas temperature, so it is possible to maintain the temperature of the exhaust gas supplied to the CO2 adsorption material at a more appropriate temperature, and it is possible to more favorably perform the adsorption / desorption of CO2 by the CO2 adsorption material.

[0019] The application according to the technical solution 3 is characterized in that, in the CO2 separation device of the internal combustion engine according to the technical solution 2, a target temperature setting unit (ECU2) is further provided, which sets a target value of the exhaust gas temperature as a target temperature (first target temperature TgasCMD1, second target temperature TgasCMD2), and the first flow rate control unit controls the flow rate of the exhaust gas flowing in the first bypass passage based on the difference between the exhaust gas temperature and the target temperature (first temperature deviation ATgas1, second temperature deviation ATgas2). Figure 5 Steps 104 to 109, steps 112 to 117, steps 118 to 123 of the method according to the technical solution 1.

[0020] According to this structure, since the flow rate of the exhaust gas flowing in the first bypass passage that bypasses the heat recovery controller is controlled based on the difference between the exhaust gas temperature and the target temperature, it is possible to adjust the temperature of the exhaust gas supplied to the CO2 adsorption material to be close to the target temperature. Thus, it is possible to maintain the temperature of the exhaust gas supplied to the CO2 adsorption material at a more appropriate temperature, and it is possible to more favorably perform the adsorption / desorption of CO2 by the CO2 adsorption material.

[0021] The application according to the technical solution 4 is characterized in that, in the CO2 separation device of the internal combustion engine according to the technical solution 3, the first flow rate control unit controls such that the lower the exhaust gas temperature is relative to the target temperature, the larger the flow rate of the exhaust gas flowing in the first bypass passage is. Figure 6 ).

[0022] According to this structure, by controlling such that the lower the temperature of the exhaust gas is, the larger the flow rate of the exhaust gas flowing in the first bypass passage is, the proportion of the exhaust gas cooled by heat exchange with the heat recovery controller is reduced, so even in the case where the temperature of the exhaust gas is relatively low, it is possible to maintain the temperature of the exhaust gas supplied to the CO2 adsorption material at a more appropriate temperature, and it is possible to more favorably perform the adsorption / desorption of CO2 by the CO2 adsorption material.

[0023] The application according to the technical solution 5 is characterized in that, in the CO2 separation device of the internal combustion engine according to the technical solution 2, a second bypass passage 64 that branches from the upstream side of the heat recovery controller of the exhaust passage, bypasses the heat recovery controller and the CO2 adsorption material, and opens to the atmosphere, and a second flow rate control unit (second flow rate control valve 66, ECU2,Figure 5 In order to adjust the exhaust temperature, the second flow control unit controls the flow rate of exhaust gas in the second bypass passage based on the detected exhaust temperature. The higher the exhaust temperature is relative to the target temperature, the greater the flow rate of exhaust gas in the second bypass passage. Figure 7 ).

[0024] According to this structure, by controlling the temperature of the exhaust gas, the flow rate of the exhaust gas flowing in the second bypass passage increases, thereby suppressing the flow of high-temperature exhaust gas into the heat dissipation controller and the CO2 adsorption material. Thus, in the event of an excessive rise in exhaust gas temperature, heat can be released through the second bypass passage, preventing overheating of the CO2 adsorption material.

[0025] The invention described in technical solution 6 of the present invention is characterized in that, in the CO2 separation device of the internal combustion engine described in technical solution 1, the exhaust heat controller has a water jacket 62, which is introduced with cooling water for cooling the internal combustion engine, and the exhaust gas introduced into the exhaust heat controller is cooled by the cooling water. The CO2 separation device of the internal combustion engine further includes: a cooling water control unit (first water pump 72, ECU2), which controls the inflow of cooling water into the water jacket; and a water temperature detection unit (first water temperature sensor 13), which detects the water temperature Tw1 of the cooling water flowing into the water jacket, and the cooling water control unit controls the inflow of cooling water into the water jacket based on the detected water temperature. Figure 10 ).

[0026] According to this structure, since the flow rate of cooling water into the water jacket is controlled based on the temperature of the cooling water, it is possible to control the flow rate so that, for example, the exhaust heat controller becomes hot through heat exchange with the exhaust gas. The higher the temperature of the cooling water, the greater the flow rate of cooling water is, resulting in a greater cooling effect. Therefore, heat exchange between the exhaust gas and the exhaust heat controller can be performed more efficiently, thus maintaining the temperature of the exhaust gas supplied to the CO2 adsorption material at a more suitable temperature, and enabling better adsorption / desorption of CO2 by the CO2 adsorption material.

[0027] The invention described in technical solution 7 is characterized in that, in the CO2 separation device of the internal combustion engine described in technical solution 6, it further comprises: a bypass passage (second bypass passage 64), which branches off from the upstream side of the exhaust heat controller of the exhaust passage, bypasses the exhaust heat controller and the CO2 adsorption material, and opens to the atmosphere; and a flow control unit (second flow control valve 66, ECU2), which controls the flow rate of the exhaust gas flowing in the bypass passage. The flow control unit controls the flow rate of the exhaust gas flowing in the bypass passage by increasing the flow rate when the detected water temperature exceeds a given value (first threshold water temperature TwREF1). Figure 5 Steps 110 and 124-127).

[0028] According to this structure, in the case where the temperature of the cooling water excessively rises due to heat exchange of the exhaust gas with the heat discharge controller, by performing control so that the flow rate of the exhaust gas flowing in the bypass passage is increased, the flow rate of the high-temperature exhaust gas flowing into the heat discharge controller and the CO2 adsorbent material can be suppressed, and thus overheating of the CO2 adsorbent material can be prevented. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a view that schematically shows a CO2 separation device to which the present application is applied together with an internal combustion engine.

[0030] Figure 2 is a block diagram showing the structure of a control system of the CO2 separation device.

[0031] Figure 3 is a graph showing the temperature characteristics of the adsorption performance of the CO2 adsorbent material.

[0032] Figure 4 is a view that schematically shows a heat discharge control assembly in the CO2 separation device.

[0033] Figure 5 is a flowchart showing exhaust gas flow rate control processing.

[0034] Figure 6 is a map for setting the opening degree of the first flow rate control valve.

[0035] Figure 7 is a map for setting the opening degree of the second flow rate control valve.

[0036] Figure 8 is a region diagram showing the actions of the first flow rate control valve and the second flow rate control valve.

[0037] Figure 9 is a flowchart showing cooling water passage switching control processing.

[0038] Figure 10 is a schematic region diagram showing the switching actions of the cooling water passage.

[0039] Figure 11 is a map for setting the rotation speed of the water pump. DETAILED DESCRIPTION

[0040] Hereinafter, a preferred embodiment of the present application will be described in detail with reference to the accompanying drawings. Figure 1 The CO2 separation device 1 of the present embodiment is schematically shown together with an internal combustion engine 3.

[0041] An internal combustion engine (hereinafter referred to as "engine") 3 is, for example, a gasoline engine mounted as a power source on a vehicle (not shown). In the engine 3, an intake passage (not shown) and an exhaust passage 4 are connected. 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 the intake passage is combusted by ignition of a spark plug (not shown), and high-temperature combustion gas generated thereby is discharged as exhaust gas to the exhaust passage 4. The exhaust passage 4 is branched into a first exhaust passage 4a and a second exhaust passage 4b downstream of the engine 3, and opens to the atmosphere via a one-way valve 5 at a respective downstream side end.

[0042] The CO2 separation device 1 is used to separate and recover CO2 (carbon dioxide) from exhaust gas flowing in the exhaust passage 4, and has a heat recovery control assembly 6, a first CO2 adsorption device 7A, a second CO2 adsorption device 7B, a compressor 8, and a storage tank 9.

[0043] The first CO2 adsorption device 7A and the second CO2 adsorption device 7B are each provided in the exhaust passage 4, and in the CO2 adsorption control described later, CO2 is adsorbed and separated from the introduced exhaust gas, and the exhaust gas from which CO2 has been removed or reduced (CO2-removed exhaust gas) is discharged to the atmosphere. Further, the CO2 adsorbed by the first CO2 adsorption device 7A and the second CO2 adsorption device 7B is desorbed from the CO2 adsorption devices 7A, 7B in the CO2 desorption control described later, and is guided to the compressor 8 provided in a merging passage 10c via the first branch passage 10a or the second branch passage 10b, and is stored in the storage tank 9 in a state compressed by the compressor 8. Hereinafter, the structures of the first CO2 adsorption device 7A and the second CO2 adsorption device 7B will be described in detail.

[0044] The first CO2 adsorption device 7A has a first heat exchanger and a first CO2 adsorber (both not shown) provided adjacent to each other. Further, the second CO2 adsorption device 7B has a second heat exchanger and a second CO2 adsorber (both not shown) provided adjacent to each other. The first exhaust passage 4a is provided to pass through the first heat exchanger of the first CO2 adsorption device 7A and the second CO2 adsorber of the second CO2 adsorption device 7B in this order from the upstream side, and opens to the atmosphere at the downstream side of the second CO2 adsorber. Further, the second exhaust passage 4b is provided to pass through the second heat exchanger of the second CO2 adsorption device 7B and the first CO2 adsorber of the first CO2 adsorption device 7A in this order from the upstream side, and opens to the atmosphere at the downstream side of the first CO2 adsorber. Further, the first CO2 adsorber and the second CO2 adsorber are each connected to the compressor 8 and the storage tank 9 via the first branch passage 10a or the second branch passage 10b, and the merging passage 10c.

[0045] The first and second heat exchangers function in such a way that they cool the exhaust gas by exchanging heat with the high-temperature exhaust gas flowing in the first and second exhaust passages 4a and 4b, and heat up the first and second CO2 adsorbers adjacent to each other by absorbing heat from the exhaust gas. Furthermore, "adjacent" does not mean direct contact; it can also mean that a material with high thermal conductivity is sandwiched between them. The first and second heat exchangers only need to be constructed to exchange heat with the exhaust gas. As a simple approach, a groove-shaped structure with an uneven cross-section to increase the heat dissipation area (e.g., a heat sink structure) can be used.

[0046] The first and second CO2 adsorbers are used to adsorb and remove CO2 from the exhaust gas, and each contains a built-in CO2 adsorption material (not shown). The CO2 adsorption material is exposed to the exhaust gas flowing through each CO2 adsorber. Furthermore, the CO2 adsorption material is composed of, for example, lithium composite oxides, zeolites, etc., and has the following properties: Figure 3 The CO2 adsorption performance corresponding to temperature is shown in the figure.

[0047] Specifically, such as Figure 3 As shown, the amount of CO2 adsorbed by the CO2 adsorbent material varies with its temperature; the lower the temperature, the greater the CO2 adsorption capacity, and the greater the adsorption capacity, which decreases as the temperature increases. In the CO2 separation device 1 of this embodiment, utilizing the temperature characteristics of such a CO2 adsorbent material, as described later, during CO2 adsorption control, the temperature of the CO2 adsorber is lowered to a low temperature (e.g., 50°C) suitable for CO2 adsorption to adsorb CO2 from the exhaust gas, and during CO2 removal control, the temperature of the CO2 adsorber is raised to a high temperature (e.g., 200°C) suitable for CO2 removal to remove the adsorbed CO2, thereby controlling CO2 adsorption / removal.

[0048] The compressor 8, for example, is an electrically powered pump that compresses the CO2 that has been separated from and flowed out of the first and second CO2 adsorbent materials, and stores it in the storage tank 10. The operation / stopping of the compressor 8 is controlled by the ECU 2.

[0049] A first exhaust passage switching valve 11 is provided at the branch between the first exhaust passage 4a and the second exhaust passage 4b ​​of the exhaust passage 4. The first exhaust passage switching valve 11 switches the flow of exhaust gas from the engine 3 to either the first exhaust passage 4a or the second exhaust passage 4b. The operation of the first exhaust passage switching valve 11 is controlled by the ECU2. That is, the ECU2 functions as an exhaust passage switching unit.

[0050] Further, in the merging portions of the first branch passage 10a and the second branch passage 10b with the merging passage 10c, a second exhaust passage switching valve 12 is provided. The second exhaust passage switching valve 12 causes CO2 desorbed from either one of the first CO2 adsorber and the second CO2 adsorber to flow into the compressor 8 and the storage tank 9 at the time of the CO2 desorption control described later, by selectively opening either one of the first branch passage 10a and the second branch passage 10b to the merging passage 10c side. The operation of the second exhaust passage switching valve 12 is controlled by the ECU 2.

[0051] On the downstream side of the second CO2 adsorber in the first exhaust passage 4a, a first CO2 concentration sensor 13 is provided, and on the downstream side of the first CO2 adsorber in the second exhaust passage 4b, a second CO2 concentration sensor 14 is provided. The first and second CO2 concentration sensors 13, 14 detect the CO2 concentration of the exhaust gas at their respective positions of installation as a first CO2 concentration CCO2A and a second CO2 concentration CCO2B. Their detection signals are output to the ECU 2.

[0052] Next, the structure of the heat rejection control assembly 6 in the CO2 separation device 1 of the present embodiment will be described. The heat rejection control assembly 6 is provided on the upstream side of the first CO2 adsorption device 7A, the second CO2 adsorption device 7B, and the first exhaust passage switching valve 11 of the exhaust passage 4, and cools the exhaust gas by heat exchange with the introduced exhaust gas. Thereby, the temperature of the exhaust gas supplied to the first CO2 adsorption device 7A and the second CO2 adsorption device 7B is adjusted to a temperature suitable for performing the CO2 adsorption control and the CO2 desorption control described later.

[0053] Figure 4 The structure of the heat rejection control assembly 6 is shown schematically. The heat rejection control assembly 6 includes a heat exchange structure 61, a water jacket 62, a first bypass passage 63, a second bypass passage 64, a first flow control valve 65, and a second flow control valve 66.

[0054] The heat exchange structure 61 is provided in the exhaust passage 4, and absorbs the heat of the exhaust gas by heat exchange with the high-temperature exhaust gas flowing in the exhaust passage 4. The heat exchange structure 61 can be any structure that enables heat exchange with the exhaust gas, and as a simple form, a structure in which the heat dissipation area is increased by a groove shape with a concave-convex cross section (for example, a fin structure) can be employed. The water jacket 62 is provided, for example, so as to surround the heat exchange structure 61, and heat exchange with the heat exchange structure 61 is performed by the cooling water filled inside. That is, by heat exchange between the exhaust gas, the heat exchange structure 61, and the cooling water of the water jacket 62, the heat of the exhaust gas moves to the cooling water, the temperature of the cooling water rises, and the temperature of the exhaust gas falls.

[0055] The water jacket 62 is connected to the water passage 71 at at least two points, and forms a circulation path for the cooling water between the water passage 71 and the water jacket 62. The inside of the water passage 71 is filled with cooling water, and a first water pump 72 for sending and circulating the cooling water, and a first radiator 73 for releasing the heat of the cooling water to the outside to cool the cooling water are provided in the water passage 71. The cooling water is heated by heat exchange with the exhaust gas while circulating between the water passage 71 and the water jacket 62 by being sent by the first water pump 72, and is cooled by passing through the first radiator 73.

[0056] Further, the water passage 71 is connected to a cooling circuit 74 of the engine 3 via a branch passage 77. The cooling circuit 74 is a circuit that passes through the engine 3, a second radiator 76, and a heater core 80, and is filled with cooling water therein. The cooling water in the cooling circuit 74 functions to cool the engine 3 by circulating in the cooling circuit 74 by being sent by a second water pump 78, and by heat exchange with the engine 3, the second radiator 76, and the heater core 80. Further, a thermostat 79 is provided in the cooling circuit 74, and switches whether the cooling water passes through the second radiator 76 by switching the passage according to the temperature of the cooling water or the like. Thus, the temperature of the cooling water in the cooling circuit 74 is stably maintained within a given temperature range (for example, 80 to 90°C).

[0057] A water passage switching valve 75 is provided at the branch point of the water passage 71 and the branch passage 77. The water passage switching valve 75 switches the flow of the cooling water flowing from the water jacket 62 to the water passage 71 to either one of the first radiator 73 side and the cooling circuit 74 side of the engine 3. The operation of the water passage switching valve 75 is controlled by the ECU 2. That is, the ECU 2 functions as a water passage switching unit.

[0058] When the water passage switching valve 75 is open to the first radiator 73 side, the cooling water circulates between the water passage 71 and the water jacket 62, and is cooled by passing through the first radiator 73 provided in the water passage 71. On the other hand, when the water passage switching valve 75 is open to the cooling circuit 74 side of the engine 3, the cooling water circulates between the water passage 71, the cooling circuit 74, and the water jacket 62. At this time, it is possible that the cooling water of the water passage 71 and the cooling water in the cooling circuit 74, which are different in temperature, are equalized in temperature by mixing with each other, and are cooled by passing through the second radiator 76 provided in the cooling circuit 74.

[0059] A first water temperature sensor 81 that detects the temperature of the cooling water flowing in the water passage 71 as a first water temperature Tw1 is provided in the water passage 71. Further, a second water temperature sensor 82 that detects the temperature of the cooling water flowing in the cooling circuit 74 of the engine 3 as a second water temperature Tw2 is provided in the cooling circuit 74 of the engine 3. The detection signals of the first water temperature Tw1 and the second water temperature Tw2 are output to the ECU 2.

[0060] Next, the structure of the first bypass passage 63, the second bypass passage 64, the first flow control valve 65, and the second flow control valve 66 of the heat rejection control assembly 6 will be described. The first bypass passage 63 branches from the heat exchange structure 61 of the exhaust passage 4 at the upstream side thereof, bypasses the heat exchange structure 61, and merges with the downstream side of the heat exchange structure 61 of the exhaust passage 4, that is, the upstream side of the first exhaust passage switching valve 11. The first flow control valve 65 is provided midway in the first bypass passage 63, and adjusts the flow rate of exhaust gas flowing in the first bypass passage 63 by changing the opening degree thereof (hereinafter referred to as V1 opening degree). Thus, the flow rate of exhaust gas flowing toward the heat rejection control assembly 6 side and the second bypass passage 64 side is adjusted. That is, as the V1 opening degree becomes larger, the flow rate of exhaust gas flowing toward the first bypass passage 63 side increases, and accordingly, the flow rate of exhaust gas flowing toward the heat rejection control assembly 6 side and the second bypass passage 64 side decreases. Thus, the flow rate of exhaust gas cooled by heat exchange with the heat rejection control assembly 6 is adjusted.

[0061] The second bypass passage 64 branches from the heat exchange structure 61 of the exhaust passage 4 at the upstream side thereof, bypasses the heat rejection control assembly 6 and the two CO2 adsorption devices 7A and 7B, and opens to the atmosphere at the downstream side end thereof via a one-way valve, similarly to the first bypass passage 63. The second flow control valve 66 is provided midway in the second bypass passage 64, and adjusts the flow rate of exhaust gas flowing in the second bypass passage 64 by changing the opening degree thereof (hereinafter referred to as V2 opening degree). Thus, the flow rate of exhaust gas flowing toward the heat rejection control assembly 6 side and the first bypass passage 63 side is adjusted. That is, as the V2 opening degree becomes larger, the flow rate of exhaust gas flowing toward the second bypass passage 64 side increases, and accordingly, the flow rate of exhaust gas flowing toward the heat rejection control assembly 6 side and the first bypass passage 63 side decreases. Thus, the flow rate of exhaust gas supplied to the two CO2 adsorption devices 7A and 7B is adjusted.

[0062] In the present specification, the so-called setting of the V1 opening degree or the V2 opening degree to full close (V1 opening degree = 0%, V2 opening degree = 0%) means that the first flow control valve 65 or the second flow control valve 66 is completely closed, and in this case, the exhaust gas does not flow to the side of the first bypass passage 63 or the second bypass passage 64 which is fully closed. Further, the so-called setting of the V1 opening degree or the V2 opening degree to full open (V1 opening degree = 100%, V2 opening degree = 100%) means that the first flow control valve 65 or the second flow control valve 66 is maximally opened. The flow rate of the exhaust gas flowing to the side of the first bypass passage 63 when the V1 opening degree is fully open, or the flow rate of the exhaust gas flowing to the side of the second bypass passage 64 when the V2 opening degree is fully open is determined by the opening degree of the other bypass passage, the flow path resistance of the heat discharge control assembly 6 and the CO2 adsorption devices 7A, 7B, and the like. The change of the V1 opening degree and the V2 opening degree is controlled by the ECU 2. That is, the ECU 2 functions as a flow control unit.

[0063] Further, on the downstream side of the heat discharge control assembly 6 of the exhaust passage 4 and on the upstream side of the first exhaust passage switching valve 11, an exhaust temperature sensor 15 is provided. The exhaust temperature sensor 15 detects the temperature of the exhaust gas at the position where it is provided, that is, the temperature of the exhaust gas flowing into the first and second CO2 adsorption devices 7A, 7B as an exhaust temperature Tgas.

[0064] Figure 2 The structure of the control system of the CO2 separation device 1 is shown. The ECU 2 is composed of a microcomputer composed of a CPU, a RAM, a ROM, and an I / O interface (none of which is shown), and the like. The ECU 2 performs CO2 adsorption / desorption control for controlling the adsorption and desorption of CO2 based on the CO2 adsorption devices 7A, 7B, based on the detection signals of the above-described CO2 concentration sensors 13, 14, and the like. Further, the ECU 2 performs exhaust flow control for adjusting the temperature of the exhaust gas introduced to the CO2 separation device using the heat discharge control assembly 6, based on the detection signals of the above-described exhaust temperature sensor 15, and the like. Furthermore, the ECU 2 performs cooling water passage switching control for switching the cooling water passage and adjusting the flow rate of the cooling water, based on the detection signals of the above-described first water temperature sensor 81 and the second water temperature sensor 82, and the like. Details of each control are described later.

[0065] Next, the outline of the flow of the adsorption and desorption of CO2 by the CO2 adsorption devices 7A, 7B and the CO2 adsorption / desorption control in the CO2 separation device 1 of the present embodiment is described. As described above, in the CO2 separation device 1 of the present embodiment, the first CO2 adsorption device 7A has a first heat exchanger and a first CO2 adsorber disposed adjacent to each other, and the second CO2 adsorption device 7B has a second heat exchanger and a second CO2 adsorber disposed adjacent to each other.

[0066] The exhaust gas flows through either of the first and second exhaust passages 4a, 4b selectively opened by the first exhaust passage switching valve 11, and through either of the first and second heat exchangers. The low-temperature exhaust gas cooled by heat exchange with the heat exchanger is adsorbed CO2 when passing through either of the first and second CO2 adsorbers, and thereafter, as CO2-removed exhaust gas (containing N2, water, etc.) is discharged to the atmosphere. On the other hand, the heat absorbed from the high-temperature exhaust gas by the heat exchanger is transferred to the CO2 adsorber on the side not introduced with the exhaust gas adjacent to the heat exchanger. Thereby, the CO2 adsorbed in the CO2 adsorber is desorbed. The desorbed CO2 flows to the merging passage 10c side through either of the first branch passage 10a and the second branch passage 10b selectively opened by the second exhaust passage switching valve 12, and is stored in the storage tank 9 in a state compressed by the compressor 8.

[0067] In the CO2 separation device 1 of the present embodiment, as described above, when the CO2 adsorption is performed in the CO2 adsorber on the side introduced with the exhaust gas, the CO2 adsorber on the side not introduced with the exhaust gas operates in a manner to desorb the CO2 adsorbed in advance. Further, under given conditions, the first exhaust passage 4a and the second exhaust passage 4b are switched by the first exhaust passage switching valve 11, and the first branch passage 10a and the second branch passage 10b are switched by the second exhaust passage switching valve 12, whereby the heat exchanger and the CO2 adsorber through which the exhaust gas passes are switched, and the CO2 adsorber opened to the compressor 8 and the storage tank 9 side is switched. Thereby, the CO2 adsorber in which CO2 is adsorbed in advance starts the desorption of the adsorbed CO2, and the CO2 adsorber in which CO2 is desorbed in advance starts the adsorption of CO2 from the newly introduced exhaust gas.

[0068] In the present embodiment, the switching of the first exhaust passage 4a and the second exhaust passage 4b by the first exhaust passage switching valve 11 and the switching of the first branch passage 10a and the second branch passage 10b by the second exhaust passage switching valve 12 are performed in a case where the CO2 concentration in the CO2-removed exhaust gas exceeds a given value, and it is determined that the CO2 adsorption is being performed in the CO2 adsorber that has reached a saturated state. The detection of the CO2 concentration in the CO2-removed exhaust gas is performed using the first and second CO2 concentration sensors 13, 14. Alternatively, a CO2 concentration sensor can be provided on the upstream side of the compressor 8, and the first exhaust passage switching valve 11 and the second exhaust passage switching valve 12 can be switched in a case where the CO2 concentration in the CO2 gas introduced into the compressor 8 is lower than a given value, and it is determined that the CO2 desorption in the CO2 adsorber in which the CO2 desorption is being performed is substantially completed.

[0069] The CO2 adsorption / detachment control of the CO2 adsorption devices 7A, 7B performed in accordance with the above procedure is as follows. First, it is determined which of the first and second CO2 adsorbers is currently performing the adsorption of CO2. Then, the first CO2 concentration CCO2A or the second CO2 concentration CCO2B is acquired from the first or second CO2 concentration sensor 13 or 14 provided on the downstream side of the CO2 adsorber that is performing the adsorption. By referring to this value, it is determined whether the CO2 adsorber that is performing the adsorption has reached the saturated state. In the case where it is determined that the CO2 adsorber that is performing the adsorption has not reached the saturated state, the CO2 adsorption performed by the current CO2 adsorber is continued. On the other hand, in the case where it is determined that the CO2 adsorber that is performing the adsorption has reached the saturated state, the adsorption / detachment of CO2 performed by each CO2 adsorber is switched by performing the switching of the first and second exhaust passage switching valves 11 and 12.

[0070] Next, the exhaust gas flow control using the exhaust heat control assembly 6 in the CO2 separation device 1 of the present embodiment will be described. Figure 5 is a flowchart showing the exhaust gas flow control process. This process is executed at given intervals in the normal operation state of the engine 3. In this process, first, in step 101 (shown as "S101". The same applies hereinafter), it is determined whether the separation / recovery of CO2 by the CO2 separation device 1 is being performed. In the case where the determination result in step 101 is "Yes", the process proceeds to step 102. On the other hand, in the case where the determination result in step 101 is "No", i.e., in the case where the CO2 separation device 1 is not in the middle of the separation / recovery of CO2, the process ends.

[0071] In step 102, the current exhaust gas temperature Tgas is acquired from the exhaust gas temperature sensor 15 provided on the downstream side of the exhaust heat control assembly 6 and on the upstream side of the first exhaust passage switching valve 11. Next, in step 103, it is determined whether the acquired exhaust gas temperature Tgas is lower than a given first target temperature TgasCMD1.

[0072] The first target temperature TgasCMD1 is set to a temperature suitable for the removal of CO2 adsorbed by the CO2 adsorbers of CO2 adsorption devices 7A and 7B, for example, 200°C. If the determination result in step 103 is "yes" and the obtained exhaust temperature Tgas is lower than the given first target temperature TgasCMD1, it is determined that the necessity of cooling the exhaust gas through the heat dissipation control component 6 is small, and the corresponding V1 opening and V2 opening are controlled in steps 104 to 109. In step 104, the difference between the exhaust temperature Tgas and the given second target temperature TgasCMD2 (=Tgas-TgasCMD2) is calculated as the first temperature deviation ΔTgas1, and the process proceeds to step 105.

[0073] The second target temperature TgasCMD2 is a higher temperature than the first target temperature TgasCMD1. It is set to the temperature at which the deterioration or damage of the CO2 adsorption material built into the CO2 adsorption device 7A or 7B may occur when exhaust gas at this temperature is introduced into the CO2 adsorber for a long time. For example, it is set to 220°C.

[0074] In step 105, based on the calculated first temperature deviation ΔTgas1, using, for example... Figure 6 Such a mapping is used to retrieve the target value of V1 opening. Then, in step 106, the V1 opening is controlled to become the retrieved target value.

[0075] exist Figure 6 In the mapping diagram, in the region where the first temperature deviation ΔTgas1 is negative, the larger the negative value of the first temperature deviation ΔTgas1, the larger the opening of V1. In the region where the first temperature deviation ΔTgas1 is above 0, the opening of V1 is set to 0%. That is, the lower the exhaust temperature Tgas, the less necessary it is to introduce the exhaust gas into the exhaust heat control component 6 for cooling, and the flow rate of the exhaust gas introduced into the first bypass passage 63 is increased by increasing the opening of V1. Through this control, the proportion of exhaust gas supplied to the CO2 adsorption device 7A or 7B while maintaining a constant temperature is increased.

[0076] On the other hand, as the exhaust temperature Tgas becomes high, the opening of V1 is set to a smaller value, thereby increasing the flow rate of the exhaust gas introduced into the heat dissipation control component 6, thus supplying the CO2 adsorption unit 7A or 7B with exhaust gas cooled by the heat dissipation control component 6. Furthermore, when the exhaust temperature Tgas is high, above the second target temperature TgasCMD2, the first flow control valve 65 is fully closed to prevent the exhaust gas from being supplied to the CO2 adsorption unit 7A or 7B without being cooled.

[0077] In a subsequent step 107, the difference (=Tgas - TgasCMD1) between the exhaust gas temperature Tgas and the given first target temperature TgasCMD1 is calculated as a second temperature deviation ΔTgas2, and the process proceeds to step 108. In step 108, based on the calculated second temperature deviation ΔTgas2, the target value of the V2 opening degree is retrieved using, for example Figure 7 the map. Then, in step 109, the V2 opening degree is controlled so as to become the retrieved target value, and the present process ends.

[0078] In Figure 7 the map, in a region where the second temperature deviation ΔTgas2 is 0 or less, it is set to V2 opening degree = 0%, and in a region where the second temperature deviation ΔTgas2 is a value greater than 0, it is set so that the higher the exhaust gas temperature Tgas, the greater the V2 opening degree. That is, in the case where the exhaust gas temperature Tgas is 0 or less than the first target temperature TgasCMD1, it is judged that there is no need to protect the heat discharge control member 6 and the CO2 adsorption devices 7A, 7B from the high-temperature exhaust gas, and by making the second flow rate control valve 66 fully closed, it is possible to supply the entire amount of the exhaust gas to the CO2 adsorption device 7A or 7B, and to maximize the adsorption / detachment of CO2.

[0079] On the other hand, in the case where the exhaust gas temperature Tgas is higher than the first target temperature TgasCMD1, the higher the exhaust gas temperature Tgas, the higher the necessity to protect the heat discharge control member 6 and the CO2 adsorption devices 7A, 7B from the high-temperature exhaust gas is judged, and by setting the V2 opening degree to be greater, the flow rate of the exhaust gas introduced into the second bypass passage 64 is increased. By such control, it is possible to prevent the heat discharge control member 6 and the CO2 adsorption devices 7A, 7B from becoming excessively high in temperature.

[0080] Further, in steps 105 to 106 and steps 108 to 109, since it is judged in step 103 that the exhaust gas temperature Tgas is lower than the first target temperature TgasCMD1, the V1 opening degree is controlled to the greater opening side, and on the other hand, the V2 opening degree is controlled to be fully closed. By such control, the majority of the exhaust gas is introduced into the first bypass passage 63, bypassing the heat discharge control member 6 and is introduced into the CO2 adsorption devices 7A, 7B, whereby it is possible to supply the exhaust gas in a state of retaining heat to the CO2 adsorption devices 7A, 7B, and it is possible to perform the adsorption / detachment of CO2 well.

[0081] On the other hand, in the case where the determination result in step 103 is "NO" and the acquired exhaust gas temperature Tgas is equal to or higher than the given first target temperature TgasCMDl, the processing proceeds to step 110. In step 110, it is determined whether or not the first water temperature Twl acquired by the first water temperature sensor 81 exceeds a given first threshold water temperature TwREFl. The first threshold water temperature TwREFl is set to a water temperature at which the water temperature of the cooling water circulating in the water passage 71 and the water jacket 62 is considered to be excessively high, for example, 95°C.

[0082] In the case where the determination result in step 110 is "YES", that is, in the case where the first water temperature Twl exceeds the given first threshold water temperature TwREFl, it is determined that the cooling water is in an overheated state, and in subsequent steps 124 to 127, control for suspending the introduction of the exhaust gas into the heat rejection control assembly 6 and the CO2 adsorption devices 7A and 7B is performed. First, in step 124, the target value of the VI opening degree is set to 0%, and in the next step 125, the actual VI opening degree is controlled to 0%. Next, in step 126, the target value of the V2 opening degree is set to 100%, and in the next step 127, the actual V2 opening degree is controlled to 100%, and the present processing is ended. By such control, the exhaust gas can be introduced into the second bypass passage 64 to bypass the heat rejection control assembly 6 and the CO2 adsorption devices 7A and 7B to be released to the atmosphere. Thus, the heat rejection control assembly 6 and the CO2 adsorption devices 7A and 7B are prevented from becoming excessively high in temperature.

[0083] On the other hand, in the case where the determination result in step 110 is "NO", that is, in the case where the first water temperature Twl is equal to or lower than the given first threshold water temperature TwREFl, it is determined that the cooling water is not in an overheated state, and the processing proceeds to step 111. In step 111, it is determined whether or not the acquired exhaust gas temperature Tgas is higher than a given second target temperature TgasCMD2.

[0084] In the case where the determination result in step 111 is "NO", that is, in the case where the exhaust gas temperature Tgas is in a temperature range equal to or higher than the given first target temperature TgasCMDl and equal to or lower than the given second target temperature TgasCMD2 (for example, a temperature range of 200°C ≤ Tgas ≤ 220°C), and it is determined that the cooling water is not in an overheated state, it is determined that the necessity of cooling the exhaust gas by the heat rejection control assembly 6 is high, and in steps 112 to 117, control of the VI opening degree and the V2 opening degree corresponding thereto is performed.

[0085] In step 112, as in step 104, the difference (=Tgas-TgasCMD2) between the exhaust gas temperature Tgas and the given second target temperature TgasCMD2 is calculated as the first temperature deviation ΔTgasl, and the processing proceeds to step 113. In step 113, as in step 105, based on the calculated first temperature deviation ΔTgasl, the target value of the Vl opening degree is retrieved using, for example Figure 6 the map. Then, in step 114, the Vl opening degree is controlled so as to become the retrieved target value.

[0086] Then, in step 115, as in step 107, the difference (=Tgas-TgasCMDl) between the exhaust gas temperature Tgas and the given first target temperature TgasCMDl is calculated as the second temperature deviation ΔTgas2, and the processing proceeds to step 116. In step 116, as in step 108, based on the calculated second temperature deviation ΔTgas2, the target value of the V2 opening degree is retrieved using, for example Figure 7 the map. Then, in step 117, the V2 opening degree is controlled so as to become the retrieved target value, and the present processing ends.

[0087] Further, in steps 113-114 and steps 116-117, since it is determined in steps 103 and 111 that the exhaust gas temperature Tgas is in the temperature range of the given first target temperature TgasCMDl or more and the given second target temperature TgasCMD2 or less, the control is performed so that the exhaust gas temperature Tgas does not exceed the second target temperature TgasCMD2, and more preferably so that the exhaust gas temperature Tgas becomes a value close to the first target temperature TgasCMDl, by controlling the Vl opening degree and the V2 opening degree according to the maps of Figure 6 and Figure 7

[0088] On the other hand, in the case where the determination result in step 111 is "Yes", that is, in the case where the exhaust gas temperature Tgas is higher than the given second target temperature TgasCMD2, it is judged that the necessity to cool the exhaust gas by the heat radiation control assembly 6 is high, and in addition, the necessity to protect the heat radiation control assembly 6 and the CO2 adsorption devices 7A, 7B from the high-temperature exhaust gas is also high, and the control of the Vl opening degree and the V2 opening degree corresponding thereto is performed in steps 118-123.

[0089] ​In step 118, as in steps 104 and 112, the difference (=Tgas - TgasCMD2) between the exhaust gas temperature Tgas and the given second target temperature TgasCMD2 is calculated as the first temperature deviation ΔTgasl, and the processing proceeds to step 119. In step 119, as in steps 105 and 113, based on the calculated first temperature deviation ΔTgasl, the target value of the Vl opening degree is retrieved using, for example, a map such as that shown in FIG. 9. Figure 6 Then, in step 120, the Vl opening degree is controlled so as to become the retrieved target value.

[0090] Then, in step 121, as in steps 107 and 115, the difference (=Tgas - TgasCMDl) between the exhaust gas temperature Tgas and the given first target temperature TgasCMDl is calculated as the second temperature deviation ΔTgas2, and the processing proceeds to step 122. In step 122, as in steps 108 and 116, based on the calculated second temperature deviation ΔTgas2, the target value of the V2 opening degree is retrieved using, for example, a map such as that shown in FIG. 10. Figure 7 Then, in step 123, the V2 opening degree is controlled so as to become the retrieved target value, and the processing ends.

[0091] Further, in steps 119 to 120 and steps 122 to 123, since it was determined in step 111 that the exhaust gas temperature Tgas was at a high temperature higher than the given second target temperature TgasCMD2, the Vl opening degree and the V2 opening degree were controlled by the maps of Figure 6 and Figure 7 respectively, so as to control the Vl opening degree to be fully closed, and on the other hand, to control the V2 opening degree to be on the larger opening side. By this control, after a portion of the exhaust gas is cooled by the heat recovery control assembly 6, the exhaust gas is supplied to the CO2 adsorption devices 7A, 7B, while the majority of the exhaust gas is introduced into the second bypass passage 64, bypassing the heat recovery control assembly 6 and the CO2 adsorption devices 7A, 7B, and is opened to the atmosphere, thereby protecting the heat recovery control assembly 6 and the CO2 adsorption devices 7A, 7B from the exhaust gas becoming excessively high in temperature.

[0092] Figure 8 is a region map that summarizes the actions of the first flow control valve 65 and the second flow control valve 66 corresponding to the exhaust gas temperature explained previously. As shown in this figure, in a region in which the exhaust gas temperature Tgas is lower than the first target temperature TgasCMDl, the Vl opening degree is controlled according to the map of Figure 6 , and on the other hand, the V2 opening degree is controlled according to the map of Figure 7the map of FIG. 9 is controlled to full close. Further, in a region where the exhaust gas temperature Tgas is higher than the second target temperature TgasCMD2, the VI opening degree is controlled to full close according to the map of FIG. 10, and the V2 opening degree is controlled to full open according to the map of FIG. 11. Figure 6 Figure 7 Figure 7 Further, in a region where the exhaust gas temperature Tgas is higher than the second target temperature TgasCMD2, the VI opening degree is controlled to full close according to the map of FIG. 10, and the V2 opening degree is controlled to full open according to the map of FIG. 11. Figure 6 Figure 7 Figure 7 Further, in a region where the exhaust gas temperature Tgas is higher than the second target temperature TgasCMD2, the VI opening degree is controlled to full close according to the map of FIG. 10, and the V2 opening degree is controlled to full open according to the map of FIG. 11.

[0093] Further, in a case where the exhaust gas temperature Tgas is higher than the second target temperature TgasCMD2, the VI opening degree is controlled to full close according to the map of FIG. 10, and the V2 opening degree is controlled to full open according to the map of FIG. 11.

[0094] By thus controlling the VI opening degree and the V2 opening degree, even in a case where the temperature of the exhaust gas flowing into the heat discharge control assembly 6 has changed, the temperature of the exhaust gas supplied to the CO2 adsorption devices 7A, 7B can be maintained at an appropriate temperature, and thus the adsorption / desorption of CO2 by the CO2 adsorption devices 7A, 7B can be performed favorably. Further, in a case where the temperature of the exhaust gas has risen excessively, overheating of the CO2 adsorption devices 7A, 7B can be prevented.

[0095] Next, the cooling water passage switching control in the CO2 separation device 1 of the present embodiment will be described. In this control, according to the water temperature of the cooling water, either one of the first radiator 73 side and the cooling circuit 74 side of the engine 3 is switched as the cooling water passage, and the flow rate of the cooling water flowing into the water jacket 62 is adjusted.

[0096] Figure 9 is a flowchart showing the cooling water passage switching control process. This process is executed every given time in a normal operation state of the engine 3. First, in step 201, it is determined whether or not the execution of the exhaust gas flow rate control described above is in progress. In a case where the determination result is "Yes", the process proceeds to the next step 202. On the other hand, in a case where the determination result is "No" and the exhaust gas flow rate control is not being executed, the present process is ended.

[0097] In step 202, the temperature of the cooling water flowing in the water passage 71, i.e., the first water temperature Tw1, and the temperature of the cooling water flowing in the cooling circuit 74 of the engine 3, i.e., the second water temperature Tw2, are respectively acquired, and the difference (= Tw1-Tw2) between the first water temperature Tw1 and the second water temperature Tw2 is calculated as the water temperature deviation ΔTw.

[0098] In a subsequent step 203, it is determined whether the calculated water temperature deviation ΔTw is greater than 0. In the case where the determination result in step 203 is "Yes", that is, in the case where the water temperature deviation ΔTw is greater than 0 (the first water temperature Twl is higher than the second water temperature Tw2), the routine proceeds to step 204. On the other hand, in the case where the determination result in step 203 is "No", that is, in the case where the first water temperature Twl is equal to or lower than the second water temperature Tw2, the routine proceeds to step 208.

[0099] In step 204, it is determined whether the temperature of the cooling water flowing in the cooling circuit 74 of the engine 3, that is, the second water temperature Tw2 is lower than a given second threshold water temperature TwREF2. The second threshold water temperature TwREF2 is set to a temperature at which it can be determined that the warm-up of the engine 3 is not completed in the case where the second water temperature Tw2 is lower than this temperature, and is set to 80°C, for example.

[0100] In the case where the determination result in step 204 is "Yes", that is, in the case where the second water temperature Tw2 is lower than the second threshold water temperature TwREF2, the routine proceeds to step 205. On the other hand, in the case where the determination result in step 204 is "No", that is, in the case where the second water temperature Tw2 is equal to or higher than the second threshold water temperature TwREF2, the routine proceeds to step 208.

[0101] In step 205, the water passage switching valve 75 is controlled to be switched to the side of the cooling circuit 74 of the engine 3, and the routine proceeds to step 206. Here, in the case where the determination result in step 204 is "Yes", it can be determined that the warm-up of the engine 3 is not completed, and therefore, by causing the cooling water of the water passage 71 side, which has a higher water temperature, to flow into the cooling circuit 74 of the engine 3, it can be determined that the warm-up of the engine 3 can be promoted. Therefore, by performing the control in step 205, it is possible to promote the warm-up of the engine 3 using the heat of the cooling water of the water passage 71 side.

[0102] On the other hand, in the case where the determination result in step 204 is "No", that is, in the case where the second water temperature Tw2 is equal to or higher than the second threshold water temperature TwREF2, the routine proceeds to step 208.

[0103] In step 208, the water passage switching valve 75 is controlled to switch to the first radiator 73 side of the water passage 71, and the process proceeds to step 209. Here, in the case where the determination result in step 203 is "No", since the first water temperature Twl on the water passage 71 side is below the second water temperature Tw2 on the cooling circuit 74 side, it is judged that even if the cooling water on the water passage 71 side flows into the cooling circuit 74, the warm-up of the engine 3 cannot be promoted. Further, in the case where the determination result in step 204 is "No", it is judged that the warm-up of the engine 3 has been completed, and thus it is judged that the warm-up does not need to be further promoted. By performing the control of step 208 in such a case, the cooling water passage is switched to the first radiator 73 side, and the cooling of the exhaust gas in the exhaust heat control assembly 6 can be efficiently performed.

[0104] Figure 10 is a region map in which the switching operation of the cooling water passage by the water passage switching valve 75 in accordance with the first water temperature Twl and the second water temperature Tw2 is summarized. As shown in this map, in a region where the water temperature deviation ΔTw is 0 or less, the cooling water passage is switched to the first radiator 73 side of the water passage 71 by the water passage switching valve 75, and thus the cooling water is rapidly cooled by the first radiator 73, and thus the cooling of the exhaust gas in the exhaust heat control assembly 6 can be efficiently performed. On the other hand, in a region where the water temperature deviation ΔTw is greater than 0, the cooling water passage is switched to the cooling circuit 74 side of the engine 3 by the water passage switching valve 75, and thus the warm-up of the engine 3 can be promoted using the heat of the cooling water on the water passage 71 side. However, in the case where the second water temperature Tw is the second threshold water temperature TwREF2 or more, since the warm-up of the engine 3 has been completed, it is judged that the warm-up does not need to be further promoted, and the cooling water passage is switched to the first radiator 73 side.

[0105] Returning to Figure 9 , then in steps 206 and 209, the target value of the rotation speed of the first water pump 72 is retrieved using, for example, a map such as Figure 11 based on the first water temperature Twl on the water passage 71 side. Then, in steps 207 and 210, the rotation speed of the first water pump 72 is controlled so as to become the retrieved target value, and the process ends.

[0106] In the map of Figure 11 , when the first water temperature Twl is lower than the second threshold water temperature TwREF2, the rotation speed of the first water pump 72 is set to be maintained at a value close to the minimum. Further, when the first water temperature Twl is the second threshold water temperature TwREF2 or more, the rotation speed of the first water pump 72 is set to be larger as the first water temperature Twl becomes higher. Furthermore, when the first water temperature Twl is higher than the first threshold water temperature TwREFl, the rotation speed of the first water pump 72 is set to be maintained at the maximum.

[0107] That is, when the first water temperature Twl is low, it means that the heat received by the cooling water from the exhaust gas via the heat rejection control assembly 6 is small, that is, the temperature of the exhaust gas is not so high, and it is judged that the cooling performance required for the heat rejection control assembly 6 is also not high, so the rotation speed of the first water pump 72 is suppressed to be low, and the flow rate of the cooling water flowing into the water jacket 62 is reduced.

[0108] On the other hand, in the case where the first water temperature Twl becomes the second threshold water temperature TwREF2 or more, it is judged that the temperature of the exhaust gas is high, and the cooling performance required for the heat rejection control assembly 6 is also high, so as the first water temperature Twl becomes high, the rotation speed of the first water pump 72 is further increased, and the flow rate of the cooling water flowing into the water jacket 62 is increased.

[0109] As such, by controlling the flow rate of the cooling water flowing into the water jacket 62 according to the first water temperature Twl, appropriate cooling performance can be obtained according to the temperature of the exhaust gas. Thus, by maintaining the temperature of the exhaust gas supplied to the CO2 adsorption devices 7A, 7B in an appropriate temperature range, the adsorption / detachment of CO2 by the CO2 adsorption material can be performed well.

[0110] In addition, the present application is not limited to the illustrated embodiments, and can be implemented in various ways. For example, in the embodiments, the structure in which the heat exchanger and the CO2 adsorber each have two and alternately switch to perform the operation of adsorption / detachment of CO2 is provided, but the structure in which the heat exchanger and the CO2 adsorber each have only one or each have three or more can also be provided.

[0111] Further, in the heat rejection control assembly of the embodiments, the structure in which the exhaust gas flows to the first and second bypass passage sides according to the opening degree of the first and second flow rate control valves by the difference in flow path resistance between the heat exchange configuration and the CO2 adsorption devices and the first and second bypass passages is provided, but the structure in which a switching valve is provided at the branch portion of the exhaust passage and the bypass passage, and the flow rate is controlled by adjustment of the opening degree of the switching valve can also be provided.

[0112] Further, the embodiments are examples in which the present application is applied to a gasoline engine mounted on a vehicle, but the present application is not limited thereto, and can be applied to other kinds of engines such as a diesel engine, and further, can be applied to engines other than for vehicles. In addition, the structure of the minute parts can be appropriately changed within the scope of the gist of the present application.

[0113] Symbol explanation

[0114] 1 CO2 separation device

[0115] 2 ECU (electronic control assembly) (first flow rate control unit, target temperature setting unit, second flow rate control unit, cooling water control unit, flow rate control unit)

[0116] 3 engine (internal combustion engine)

[0117] 4 exhaust passage

[0118] 6 heat discharge control assembly (heat discharge controller, first bypass passage, second bypass passage, bypass passage)

[0119] 7A first CO2 adsorption device (CO2 adsorption material)

[0120] 7B second CO2 adsorption device (CO2 adsorption material)

[0121] 15 exhaust gas temperature sensor (exhaust gas temperature detection unit)

[0122] 61 heat exchange configuration (heat discharge controller)

[0123] 62 water jacket

[0124] 63 first bypass passage

[0125] 64 second bypass passage (bypass passage)

[0126] 65 first flow control valve (first flow control unit)

[0127] 66 second flow control valve (second flow control unit, flow control unit)

[0128] 72 first water pump (cooling water control unit)

[0129] 81 first water temperature sensor (water temperature detection unit)

[0130] 82 second water temperature sensor (water temperature detection unit)

[0131] Tgas exhaust gas temperature

[0132] TgasCMD1 first target temperature (target temperature)

[0133] TgasCMD2 second target temperature (target temperature)

[0134] ΔTgas1 first temperature deviation (difference between exhaust gas temperature and target temperature)

[0135] ΔTgas2 second temperature deviation (difference between exhaust gas temperature and target temperature)

[0136] Tw1 first water temperature

[0137] Tw2 second water temperature

Claims

1. A CO2 separation device for an internal combustion engine, which is installed in the exhaust system of an internal combustion engine and separates CO2 from the exhaust gas, characterized in that, Possessing: an exhaust passage connected to the internal combustion engine for exhaust gas to flow; a CO2 adsorption material provided in the exhaust passage, which adsorbs CO2 in the exhaust gas at a given low temperature and releases the adsorbed CO2 at a given high temperature; a heat discharge controller provided on the upstream side of the CO2 adsorption material in the exhaust passage, which is introduced with the exhaust gas and absorbs heat of the exhaust gas by heat exchange with the exhaust gas, the heat discharge controller having a water jacket into which cooling water for cooling the internal combustion engine is introduced and which cools the exhaust gas introduced into the heat discharge controller by the cooling water; a water passage switching unit provided at a connection portion of an internal combustion engine cooling circuit in which the cooling water for cooling the internal combustion engine circulates and an exhaust gas cooling circuit in which the cooling water introduced into the water jacket circulates, the water passage switching unit being configured so as to be able to switch the water passage state of the cooling water between a first water passage state in which the cooling water passes through only the exhaust gas cooling circuit and a second water passage state in which the cooling water passes through both the exhaust gas cooling circuit and the internal combustion engine cooling circuit; a first water temperature detection unit that detects the water temperature of the cooling water flowing into the water jacket, i.e., a first water temperature; and a second water temperature detection unit that detects the water temperature of the cooling water for cooling the internal combustion engine, i.e., a second water temperature; the water passage switching unit switches the water passage to the second water passage state when the first water temperature is higher than the second water temperature and the second water temperature is lower than a given threshold water temperature.

2. The CO2 separation device for an internal combustion engine according to claim 1, characterized in that the CO2 separation device for an internal combustion engine is provided with: an exhaust gas temperature detection unit provided on the downstream side of the heat discharge controller in the exhaust passage and on the upstream side of the CO2 adsorption material, which detects the temperature of the exhaust gas flowing into the CO2 adsorption material as an exhaust gas temperature; a first bypass passage that branches from the upstream side of the heat discharge controller in the exhaust passage, merges with the upstream side of the exhaust gas temperature detection unit while bypassing the heat discharge controller; and a first flow rate control unit that controls the flow rate of the exhaust gas flowing in the first bypass passage in accordance with the detected exhaust gas temperature in order to adjust the exhaust gas temperature.

3. The CO2 separation device for an internal combustion engine according to claim 2, characterized in that the CO2 separation device for an internal combustion engine is further provided with a target temperature setting unit that sets a target value of the exhaust gas temperature as a target temperature, the first flow rate control unit controls the flow rate of the exhaust gas flowing in the first bypass passage based on the difference between the exhaust gas temperature and the target temperature.

4. The CO2 separation device for an internal combustion engine according to claim 3, characterized in that the first flow rate control unit controls so that the lower the exhaust gas temperature is relative to the target temperature, the greater the flow rate of the exhaust gas flowing in the first bypass passage is.

5. The CO2 separation device for an internal combustion engine according to claim 3, characterized in that the CO2 separation device for an internal combustion engine is further provided with: ​ a second bypass passage branching from an upstream side of the exhaust passage with respect to the heat discharge controller, bypassing the heat discharge controller and the CO2 adsorbent material, and opening to the atmosphere; and a second flow rate control unit that controls a flow rate of exhaust gas flowing in the second bypass passage in accordance with the detected exhaust gas temperature for adjusting the exhaust gas temperature, the second flow rate control unit being controlled such that the higher the exhaust gas temperature is with respect to the target temperature, the larger the flow rate of exhaust gas flowing in the second bypass passage is.

6. The CO2 separation device of an internal combustion engine according to claim 1, characterized in that the CO2 separation device of an internal combustion engine further comprises: a cooling water control unit that controls an inflow amount of the cooling water into the water jacket; the cooling water control unit controls the inflow amount of the cooling water into the water jacket in accordance with the detected first and second water temperatures.

7. The CO2 separation device of an internal combustion engine according to claim 6, characterized in that the CO2 separation device of an internal combustion engine further comprises: a bypass passage branching from an upstream side of the exhaust passage with respect to the heat discharge controller, bypassing the heat discharge controller and the CO2 adsorbent material, and opening to the atmosphere; and a flow rate control unit that controls a flow rate of exhaust gas flowing in the bypass passage, the flow rate control unit being controlled such that the flow rate of exhaust gas flowing in the bypass passage is increased in a case where the detected water temperature exceeds a given value.

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