JP2014177878A - Egr system and egr method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR system and an EGR method that can suppress pumping loss caused by EGR.SOLUTION: An EGR system 30 includes: an EGR passage 31 connecting an intake passage 16 with an exhaust passage 20; an absorption part 36 that is disposed downstream of a connection portion between the exhaust passage 20 and the EGR passage 31 in the exhaust passage 20 and absorbs carbon dioxide in exhaust gas by making an absorbing solution for absorbing carbon dioxide come into contact with the exhaust gas; a regeneration part 39 for heating the absorbing solution that has absorbed the carbon dioxide in the absorption part 36 to regenerate the carbon dioxide absorbed in the absorbing solution; a circulation pump 38 for circulating the absorbing solution between the absorption part 36 and the regeneration part 39 through first and second circulation passages 37, 41; and a supply passage 43 that connects the regeneration part 39 with the EGR passage 31 to supply the carbon dioxide regenerated by the regeneration part 39 to the EGR passage 31.

Description

  The technology of the present disclosure relates to an EGR system and an EGR method for recirculating a part of exhaust gas from an exhaust passage of an engine to an intake passage.

  Conventionally, as disclosed in Patent Document 1, for example, as a method of reducing NOx contained in exhaust gas by lowering the combustion temperature, exhaust gas recirculation (EGR: recirculating part of exhaust gas from the exhaust side of the engine to the intake side) Exhaust Gas Recirculation) is known. In EGR, carbon dioxide contained in intake air is increased by recirculating exhaust gas to intake air, and the combustion temperature is lowered by absorbing a part of heat during combustion in the carbon dioxide.

JP 2002-332879 A

  On the other hand, in order to perform EGR, it is necessary to maintain a state in which the pressure on the exhaust side is higher than the pressure on the intake side, so that the carbon dioxide contained in the intake is increased, that is, a large amount of EGR gas In a situation where the pressure is required, the pressure on the exhaust side must be maintained at a higher pressure. Increasing the pressure on the exhaust side increases the pumping loss of the engine, leading to a decrease in engine output and an increase in fuel consumption. For this reason, it is strongly desired to suppress the pumping loss of the engine due to EGR.

  An object of the technology of the present disclosure is to provide an EGR system and an EGR method capable of suppressing an engine pumping loss due to EGR.

  An EGR system that solves the above-described problems is an EGR passage that connects an intake passage and an exhaust passage of an engine, and an exhaust gas that flows downstream from a portion of the exhaust passage where the EGR passage is connected to an absorbing liquid. An absorption unit that absorbs carbon dioxide contained in the exhaust gas with the absorption liquid, and a regeneration unit that regenerates carbon dioxide absorbed in the absorption liquid by heating the absorption liquid that has absorbed the carbon dioxide, A circulation unit that circulates the absorbing liquid between the absorption unit and the regeneration unit, and the regeneration unit and the EGR passage are connected, and the carbon dioxide regenerated by the regeneration unit is supplied to the EGR passage. A supply passage.

  An EGR method that solves the above problem is an EGR method that recirculates part of the exhaust gas from the exhaust passage of the engine to the intake passage through the EGR passage, rather than a portion where the EGR passage is connected in the exhaust passage. The exhaust gas downstream of the exhaust passage is brought into contact with the absorbing liquid, carbon dioxide contained in the exhaust gas is absorbed by the absorbing liquid, and the absorbing liquid that has absorbed the carbon dioxide is heated to be contained in the absorbing liquid. Carbon dioxide is regenerated, and the regenerated carbon dioxide is supplied to the EGR passage.

  According to these EGR system and EGR method, carbon dioxide contained in the exhaust gas is absorbed by the absorption unit, and the absorbed carbon dioxide is regenerated by the regeneration unit. Then, the high-concentration carbon dioxide regenerated in the regenerating unit is supplied to the EGR passage through the supply passage. That is, the EGR gas supplied with carbon dioxide is composed of exhaust gas that has flowed into the EGR passage and carbon dioxide that has been absorbed from the exhaust gas that has not flowed into the EGR passage and has a higher concentration. Thereby, compared with the case where EGR gas is only exhaust gas flowing into the EGR passage, the concentration of carbon dioxide in the EGR gas is increased, and in order to obtain the same amount of carbon dioxide, the pressure of the exhaust gas in the EGR passage, and thus, The exhaust pressure in the exhaust passage is suppressed. Therefore, the pumping loss of the engine is suppressed.

The EGR system preferably includes a cooling unit that cools the absorbent flowing from the regeneration unit to the absorption unit.
According to this configuration, the cooling liquid is actively cooled by the cooling unit when fed from the regeneration unit to the absorption unit. As a result, compared to the case where cooling by the cooling unit is not performed, the amount of absorption liquid used is reduced and carbon dioxide contained in the exhaust gas is easily absorbed by the absorption unit.

In the EGR system, it is preferable that the regeneration unit includes a heat exchange unit that performs heat exchange between the exhaust gas flowing through the exhaust passage and the absorbing liquid.
According to this configuration, since the absorption liquid is heated using the exhaust heat of the exhaust, for example, the exhaust heat of the exhaust is used more effectively than when a heater or the like for heating the absorption liquid is provided separately. At the same time, the configuration of the EGR system is simplified.

In the EGR system, it is preferable that the exhaust gas flowing through the absorption portion is exhaust gas that has passed through a portion where the heat exchange is performed in the exhaust passage.
According to this configuration, the temperature of the exhaust gas flowing into the absorption unit is lowered by the amount of heating of the absorption liquid in the regeneration unit. Therefore, in the absorption part, the temperature rise of the absorption liquid accompanying the inflow of exhaust gas is suppressed, so that carbon dioxide is easily absorbed by the absorption liquid.

In the EGR system, it is preferable that the supply passage includes a suppression unit that suppresses the EGR gas flowing through the EGR passage from flowing into the supply passage.
According to this configuration, since the inflow of EGR gas from the EGR passage to the supply passage is suppressed by the suppression portion, the concentration of carbon dioxide in the supply passage in the portion closer to the regeneration portion than the suppression portion is higher than that of EGR gas. High state is easily maintained. As a result, by supplying gas from the supply passage to the EGR passage, the concentration of carbon dioxide in the EGR gas rises with a high probability.

  In the EGR system, the regeneration unit includes a heat exchanging unit that performs heat exchange between the exhaust gas flowing through the exhaust passage and the absorbing liquid, and the absorption unit and the regeneration unit perform exhaust gas flowing through the exhaust passage. It is preferable to be disposed downstream of the exhaust purification device to be purified.

  According to this configuration, the absorption unit absorbs carbon dioxide from the exhaust gas purified by the exhaust gas purification device, and the regeneration unit absorbs heat from the exhaust gas purified by the exhaust gas purification device. As a result, the contamination of the absorbing liquid can be suppressed as compared with the case where the absorbing portion is disposed upstream of the exhaust purification device. Further, since the temperature drop of the exhaust gas flowing into the exhaust purification device is suppressed, for example, the catalyst provided in the exhaust purification device is easily maintained at the activation temperature.

  In the EGR system, it is preferable that the EGR passage includes an EGR cooler that cools EGR gas flowing through the EGR passage, and the supply passage is connected to an upstream side of the EGR cooler in the EGR passage.

  According to this configuration, since the EGR cooler cools the EGR gas containing carbon dioxide regenerated by the regenerating unit, the concentration of carbon dioxide in the EGR gas is further increased.

It is a figure which shows the structure of one Embodiment which actualized the EGR system in the technique of this indication with the engine by which the EGR system was mounted. It is a figure explaining the operation | movement aspect of a reproducing | regenerating apparatus using the flow of exhaust gas. It is a block diagram which shows the structure of the absorption part of an EGR system in a modification, and the reproduction | regeneration part vicinity, Comprising: It is the figure which abbreviate | omitted and showed a part of structure contained in the reproducing | regenerating apparatus.

Hereinafter, an embodiment of the EGR system and the EGR method according to the present disclosure will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, a cylinder block 11 of a diesel engine 10 (hereinafter simply referred to as an engine 10) is formed with six cylinders 12 arranged in a row, and each cylinder 12 includes an injector 13. Fuel is injected. An intake manifold 14 for supplying intake air to each cylinder 12 and an exhaust manifold 15 into which exhaust from each cylinder 12 flows are connected to the cylinder block 11.

  A compressor 18 constituting a turbocharger 17 is attached to the intake passage 16, and an intercooler 19 for cooling intake air compressed by the compressor 18 is attached to the downstream side of the compressor 18.

  An exhaust passage 20 is connected to the exhaust manifold 15. A turbine 22 that is connected to the compressor 18 via a connecting shaft 21 and constitutes the turbocharger 17 is attached to the exhaust passage 20. An exhaust purification device 23 is disposed downstream of the turbine 22 in the exhaust passage 20. The exhaust purification device 23 is configured by a DPF that captures particulates contained in the exhaust, a catalyst that reduces NOx contained in the exhaust, and the like.

  The engine 10 is equipped with an EGR system 30 that performs EGR using the exhaust gas that has passed through the exhaust gas purification device 23. The EGR system 30 includes an EGR passage 31 that connects the upstream side of the compressor 18 in the intake passage 16 and the downstream side of the exhaust purification device 23 in the exhaust passage 20. An EGR cooler 32 that cools the EGR gas that is a gas flowing through the EGR passage 31 and an EGR valve 33 that is a flow rate adjustment valve that adjusts the flow rate of the EGR gas in the EGR passage 31 are attached to the EGR passage 31. When the EGR valve 33 is in the open state, a part of the exhaust flows into the EGR passage 31 and the remainder of the exhaust flows into the regenerator 35 of the EGR system 30. When the EGR valve 33 is in the closed state, the exhaust gas flows into the regenerator 35 without flowing into the EGR passage 31.

  In the regenerator 35, the absorbing portion 36 attached to the exhaust passage 20 and the regenerating portion 39 attached to the exhaust passage 20 are arranged in order from the downstream side of the exhaust passage 20. Part or all of the exhaust gas flowing into the regenerator 35 passes through the regenerator 39 and then flows into the absorber 36.

  The absorption part 36 stores an absorption liquid A which is an alkaline solution capable of selectively dissolving carbon dioxide. The absorbing liquid A is an aqueous solution containing, for example, monoethanolamine as an absorbent. In the absorption unit 36, carbon dioxide contained in the exhaust is absorbed by the absorption liquid A due to contact between the absorption liquid A and the exhaust.

  A first circulation passage 37 and a second circulation passage 41 are connected in parallel with each other between the absorption portion 36 and the regeneration portion 39. A circulation pump 38 is attached in the middle of the first circulation passage 37, and when the circulation pump 38 is driven, the absorbent A in the absorption portion 36 is sent to the regeneration portion 39 through the first circulation passage 37. Circulation pump 38 continues to be driven from when engine 10 is started to when it is stopped. In the middle of the second circulation passage 41, an absorption liquid cooler 42, which is a cooling unit, is attached. Cool liquid A.

  The regeneration unit 39 includes a heat exchanging unit 40 that receives heat from the exhaust gas flowing through the exhaust passage 20, and heats the absorbing liquid A sent from the absorbing unit 36 with the heat obtained by the heat exchanging unit 40. Then, the regeneration unit 39 raises the temperature of the absorption liquid A to, for example, 130 ° C. or more, and desorbs carbon dioxide absorbed in the absorption liquid A from the absorption liquid A as carbon dioxide, that is, regenerates carbon dioxide. The regeneration unit 39 returns the absorption liquid A from which carbon dioxide has been desorbed to the absorption unit 36 through the absorption liquid cooler 42. That is, the first circulation passage 37, the circulation pump 38, and the second circulation passage 41 constitute a circulation section, and the absorption liquid A is absorbed by the absorption section 36 and carbon dioxide is regenerated by the regeneration section 39. It circulates between the absorption part 36 and the reproduction | regeneration part 39, repeating.

  The regeneration unit 39 is connected to a portion of the EGR passage 31 that is upstream of the EGR cooler 32 through the supply passage 43. A flow rate adjustment valve 45 and a check valve 46 are attached in the middle of the supply passage 43, and the flow rate adjustment valve 45 is attached to the regeneration unit 39 side of the check valve 46. The flow rate adjusting valve 45 and the check valve 46 constitute a suppression unit 44. A safety valve 47 that releases carbon dioxide from the supply passage 43 when the pressure in the supply passage 43 exceeds a predetermined threshold is attached to the supply passage 43. Carbon dioxide released from the supply passage 43 by the safety valve 47 flows into the tail pipe 49 which is a part of the exhaust passage 20 through the discharge passage 48.

  The flow rate adjusting valve 45 adjusts the flow rate of carbon dioxide flowing from the regeneration unit 39 toward the EGR passage 31 by changing the flow path cross-sectional area of the supply passage 43. The check valve 46 is disposed closer to the EGR passage 31 than the flow rate adjustment valve 45, and permits the flow of gas flowing from the regeneration unit 39 toward the EGR passage 31, while passing from the EGR passage 31 to the regeneration unit 39. The flow of gas flowing in the direction is prohibited. The carbon dioxide generated in the regeneration unit 39 flows from the regeneration unit 39 into the supply passage 43 and flows out upstream of the EGR cooler 32 in the EGR passage 31.

  The opening degree of the EGR valve 33 and the flow rate adjustment valve 45 is controlled separately by the ECU 50. The ECU 50 controls the opening degree of the EGR valve 33 and the flow rate adjustment valve 45 based on signals from various sensors that detect various types of information related to the engine 10, and the EGR valve 33 is in an open state with respect to the flow rate adjustment valve 45. The valve opening state is controlled on the condition. The information includes, for example, the rotational speed and fuel injection amount of the engine 10, the pressure and oxygen concentration in the intake manifold 14, the pressure and oxygen concentration in the exhaust manifold 15, and the amount of air sucked into the intake passage 16. The air amount, the pressure of the exhaust gas immediately before flowing into the EGR passage 31, and the like can be mentioned. Examples of the information include the pressure of EGR gas and the concentration of carbon dioxide immediately before flowing into the intake passage 16, the temperature of the absorbing liquid A in the regeneration unit 39, and the pressure of carbon dioxide in the supply passage 43. The concentration means mass concentration or substance amount concentration.

Next, the operation of the EGR system 30 configured as described above will be described.
Exhaust gas discharged from the engine 10 is purified by the exhaust gas purification device 23 when passing through the turbine 22. A part of the exhaust gas purified by the exhaust gas purification device 23 flows into the EGR passage 31 and the rest flows into the regeneration device 35 when the EGR valve 33 is in the open state. Further, when the EGR valve 33 is in the closed state, all the exhaust flows into the regenerator 35.

  As shown in FIG. 2, the exhaust gas flowing into the regeneration device 35 first flows into the regeneration unit 39. The exhaust gas flowing through the regeneration unit 39 heats the absorbing liquid A in the regeneration unit 39 via the heat exchange unit 40. Therefore, the exhaust gas flowing out from the regeneration unit 39 is in a state where heat has been taken away by the absorbent A, and the temperature of the exhaust gas flowing out from the regeneration unit 39 is lower than that before flowing into the regeneration unit 39. The exhaust gas that has flowed out of the regeneration unit 39 then flows into the absorption unit 36. Exhaust gas flowing through the absorption part 36 absorbs part of the carbon dioxide contained in the exhaust gas into the absorption liquid A by contact with the absorption liquid A. And the exhaust gas which flows out from the absorption part 36 is discharged | emitted to air | atmosphere through a muffler etc.

  On the other hand, in the regenerator 35, the circulation pump 38 is driven as the engine 10 is started, and the circulation of the absorbing liquid A between the absorbing unit 36 and the regenerating unit 39 is started. The absorbing liquid A that has absorbed carbon dioxide in the absorption unit 36 is sent to the regeneration unit 39 through the first circulation passage 37. The absorbent A sent to the regeneration unit 39 is heated by the exhaust gas through the heat exchange unit 40 to regenerate carbon dioxide. As a result, the regeneration unit 39 generates carbon dioxide. The absorption liquid A heated in the regeneration unit 39 flows into the absorption unit 36 through the second circulation passage 41. At this time, the absorbing liquid A flowing through the second circulation passage 41 is cooled by the absorbing liquid cooler 42. Then, the absorption liquid A cooled by the absorption liquid cooler 42 again absorbs the exhaust carbon dioxide in the absorption section 36 and is sent to the regeneration section 39 again.

  The carbon dioxide generated in the regeneration unit 39 is stored in the regeneration unit 39 and the supply passage 43 when the flow rate adjustment valve 45 is in a closed state. At this time, since the inflow of the exhaust gas flowing into the EGR passage 31 into the supply passage 43 is suppressed by the check valve 46, the concentration of carbon dioxide in the supply passage 43 is maintained higher than that in the exhaust gas. During this time, in the supply passage 43, an excessive increase in pressure is suppressed by opening the safety valve 47.

  On the other hand, when the flow rate adjustment valve 45 is in the open state, the carbon dioxide generated in the regeneration unit 39 is supplied to the EGR passage 31 through the supply passage 43. As a result, the EGR gas becomes a gas containing the exhaust gas flowing into the EGR passage 31 from the exhaust passage 20 and the carbon dioxide absorbed from the exhaust gas not flowing into the EGR passage 31. Then, the EGR gas is cooled by the EGR cooler 32 to further increase the concentration of carbon dioxide, and then supplied to the intake passage 16. As a result, the gas having a higher carbon dioxide concentration is supplied to the engine 10 than when only the exhaust gas flowing into the EGR passage 31 is the EGR gas.

As described above, according to the EGR system and the EGR method of the above embodiment, the following effects can be obtained.
(1) The EGR gas supplied to the intake passage 16 includes exhaust gas that has flowed into the EGR passage 31 and carbon dioxide in the exhaust gas that has not flowed into the EGR passage 31. Therefore, compared with the case where EGR gas is only exhaust gas flowing into the EGR passage, the concentration of carbon dioxide in the EGR gas is increased, so that the same amount of carbon dioxide is obtained. The pressure of the exhaust gas in the passage 20 is suppressed. As a result, engine pumping loss is suppressed.

  (2) The concentration of carbon dioxide in the EGR gas is also realized by increasing the pressure of the exhaust gas flowing into the EGR passage 31, that is, increasing the output and rotation of the turbine 22. However, such a method requires high output and high rotation of the turbine 22, so that the load on the turbine 22 becomes large. In this regard, in the EGR system 30, the concentration of carbon dioxide in the EGR gas is increased without increasing the pressure of the exhaust gas flowing into the EGR passage 31. Therefore, when EGR is executed, the load on the turbine 22 is reduced.

  (3) In the regenerator 35, the absorbing liquid A circulates between the absorbing part 36 and the regenerating part 39, and the absorbing liquid A flowing from the regenerating part 39 to the absorbing part 36 is actively cooled by the absorbing liquid cooler 42. Done. As a result, compared to the case where the absorption liquid A is not cooled by the absorption liquid cooler 42, the amount of the absorption liquid A used is reduced and the carbon dioxide contained in the exhaust gas is easily absorbed by the absorption portion 36.

  (4) In the regeneration unit 39, the absorption liquid A is heated by the heat exchange unit 40 using the exhaust heat of the exhaust. For this reason, for example, the configuration of the EGR system 30 is simplified as compared with a case where a heater or the like for heating the absorbing liquid A is provided separately, and exhaust heat of exhaust gas is effectively used.

  (5) The temperature of the exhaust gas flowing into the absorption unit 36 is lowered by the amount of heating of the absorption liquid A by the regeneration unit 39. Therefore, in the absorption part 36, the temperature rise of the absorption liquid A accompanying the inflow of exhaust gas is suppressed, so that the carbon dioxide in the exhaust gas is easily absorbed by the absorption liquid A.

  (6) The flow of EGR gas from the EGR passage 31 to the supply passage 43 is suppressed by the suppression unit 44, so that the concentration of carbon dioxide in the supply passage 43 in the portion closer to the regeneration unit 39 than the suppression unit 44 is EGR. It becomes easier to maintain a higher state than the gas. As a result, by supplying gas from the supply passage 43 to the EGR passage 31, the concentration of carbon dioxide in the EGR gas increases with a high probability.

  (7) The absorption unit 36 absorbs carbon dioxide from the exhaust gas purified by the exhaust gas purification device 23. As a result, the contamination of the absorbing liquid A is suppressed as compared with the case where the absorbing portion 36 is disposed upstream of the exhaust purification device 23.

  (8) The regeneration unit 39 heats the absorption liquid A with the exhaust gas purified by the exhaust gas purification device 23. Therefore, the exhaust heat of the exhaust is efficiently used when the exhaust purification device 23 is heated.

  (9) The EGR cooler 32 cools the EGR gas composed of the exhaust gas flowing into the EGR passage 31 and the carbon dioxide from the supply passage 43. That is, the EGR gas whose carbon dioxide concentration is increased is further cooled and then supplied to the intake passage 16. Thereby, since the combustion temperature is lowered even when the EGR gas is not cooled, the NOx contained in the exhaust gas is further reduced.

  (10) Since the circulation pump 38 is continuously driven from the start time to the stop time of the engine 10, the absorbing liquid A continues to circulate between the absorbing portion 36 and the regenerating portion 39. Therefore, the stagnation of the absorbing liquid A in the regenerating unit 39 is suppressed, so that an excessive temperature rise of the absorbing liquid A in the regenerating unit 39 is suppressed.

In addition, the said embodiment can also be suitably changed and implemented as follows.
The connection position of the supply passage 43 with respect to the EGR passage 31 may be on the downstream side of the EGR cooler 32. Note that the EGR cooler 32 may be omitted from the EGR passage 31.

  At least one of the absorption unit 36 and the regeneration unit 39 may be arranged on the upstream side of the exhaust purification device 23 in the exhaust passage 20, and the absorption unit 36 is upstream of the regeneration unit 39 in the exhaust passage 20 May be arranged.

  -The suppression part 44 should just be able to suppress inflow of the exhaust_gas | exhaustion from the EGR channel | path 31 to the supply channel | path 43, and should just be provided with at least one of the non-return valve 46 and the flow regulating valve 45. FIG. Note that the suppression unit 44 may be omitted from the supply passage 43.

  The heat exchanging unit 40 may heat the absorption liquid A using the exhaust gas that has passed through the absorption unit 36, the exhaust gas that has passed through the absorption unit 36, and the exhaust gas that has passed through the absorption unit 36. The absorbing liquid A may be heated using

-The method of heating the absorption liquid A in the regeneration unit 39 is not limited to heat exchange with the exhaust. For example, the absorption liquid A may be heated using an electric heater or the like.
In the process of being sent from the regeneration unit 39 to the absorption unit 36, the absorption liquid cooler 42 may be omitted from the second circulation passage 41 if the temperature of the absorption liquid A decreases to a temperature at which carbon dioxide can be absorbed.

  The bypass passage that bypasses the middle of the exhaust passage 20 may be separately provided, and the exhaust gas flowing into the absorption unit 36 may be exhaust gas flowing through the bypass passage. At this time, the portion branched from the exhaust passage 20 toward the absorbing portion 36 may be downstream of the portion where the EGR passage 31 is connected in the exhaust passage 20.

  A bypass path that bypasses the middle of the exhaust path 20 may be provided separately, and the exhaust gas flowing into the regeneration unit 39 may be exhaust gas flowing through the bypass path. The portion branched from the exhaust passage 20 toward the regeneration unit 39 may be downstream of the portion where the EGR passage 31 is connected in the exhaust passage 20, or the EGR passage 31 in the exhaust passage 20. May be upstream of the portion to which is connected.

  The safety valve 47 may be omitted from the supply passage 43. Under such a configuration, for example, when it is determined that the pressure in the supply passage 43 is excessively high based on a detection signal from the supply passage pressure sensor, the flow rate adjustment valve 45 is opened regardless of the EGR. It is preferable to make it.

The regeneration device 35 may include a device that forcibly sends the carbon dioxide in the supply passage 43 into the EGR passage 31.
In the middle of the second circulation passage 41, a pump that sucks the absorbing liquid A in the regeneration unit 39 and discharges the sucked absorbing liquid A to the absorbing unit 36 may be attached. According to such a configuration, the absorption liquid A is circulated more smoothly between the absorption unit 36 and the regeneration unit 39.

  As shown in FIG. 3, when the regeneration unit 39 and the absorption unit 36 are attached to the exhaust passage 20, the EGR system 30 bypasses the regeneration unit 39 and the absorption unit 36 and is opened and closed by the ECU 50. A bypass passage 57 including a switching valve 56 may be further provided.

  According to such a configuration, for example, when the ECU 50 determines that the temperature of the absorbing liquid A in the regeneration unit 39 is excessively high, the switching valve 56 is opened, and the exhaust passage 20 is connected to the regeneration unit 39 and the absorption unit 36. A part of the exhaust is bypassed. Thereby, the exhaust gas flowing into the regeneration unit 39 is reduced, and an excessive temperature rise of the absorbing liquid A is suppressed.

  Note that such a bypass passage may be a passage that is not limited to the regeneration unit 39 and the absorption unit 36 but only the regeneration unit 39, or a passage that is a bypass target only of the absorption unit 36. Also good. Moreover, the channel | path which can selectively detour the reproduction | regeneration part 39 and the absorption part 36 may be sufficient.

  The absorption liquid may be any liquid that can selectively dissolve carbon dioxide and can regenerate the dissolved carbon dioxide by heating. The absorbent is not limited to monoethanolamine, for example, diethanolamine, triethanolamine. , Methyldiethanolamine, diisopropanolamine may be used.

  The engine to which the EGR system 30 is applied may be a gasoline engine.

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 11 ... Cylinder block, 12 ... Cylinder, 13 ... Injector, 14 ... Intake manifold, 15 ... Exhaust manifold, 17 ... Intake passage, 17 ... Turbocharger, 18 ... Compressor, 19 ... Intercooler, 20 ... Exhaust passage , 21 ... connecting shaft, 22 ... turbine, 23 ... exhaust purification device, 30 ... EGR system, 31 ... EGR passage, 32 ... EGR cooler, 33 ... EGR valve, 35 ... regenerator, 36 ... absorber, 37 ... first Circulation passage, 38 ... circulation pump, 39 ... regeneration section, 40 ... heat exchange section, 41 ... second circulation passage, 42 ... absorbent liquid cooler, 43 ... supply passage, 44 ... suppression section, 45 ... flow rate adjustment valve, 46 ... Check valve, 47 ... Safety valve, 48 ... Release passage, 49 ... Tail pipe, 50 ... ECU, 56 ... Switching valve, 5 ... bypass passage.

Claims (8)

An EGR passage connecting the intake passage and the exhaust passage of the engine;
An absorber that absorbs carbon dioxide contained in the exhaust gas by contacting the exhaust gas flowing downstream from the site where the EGR passage is connected in the exhaust gas passage with the absorbing liquid; and
A regeneration unit that regenerates carbon dioxide absorbed in the absorption liquid by heating the absorption liquid that has absorbed the carbon dioxide;
A circulation unit for circulating the absorption liquid between the absorption unit and the regeneration unit;
An EGR system comprising: a supply passage that connects the regeneration section and the EGR passage and supplies the carbon dioxide regenerated by the regeneration section to the EGR passage. The EGR system according to claim 1, further comprising a cooling unit that cools the absorbing liquid flowing from the regeneration unit to the absorbing unit. The EGR system according to claim 1, wherein the regeneration unit includes a heat exchange unit that performs heat exchange between the exhaust gas flowing through the exhaust passage and the absorbing liquid. The EGR system according to claim 3, wherein the exhaust gas flowing through the absorption unit is exhaust gas that has passed through a portion where the heat exchange is performed in the exhaust passage. The supply passage is
The EGR system according to any one of claims 1 to 4, further comprising a suppression unit that suppresses the EGR gas flowing through the EGR passage from flowing into the supply passage. The regeneration unit includes a heat exchange unit that exchanges heat between the exhaust flowing through the exhaust passage and the absorbing liquid,
The EGR system according to any one of claims 1 to 5, wherein the absorption unit and the regeneration unit are disposed on a downstream side of an exhaust purification device that purifies exhaust gas flowing through the exhaust passage. The EGR passage includes an EGR cooler that cools EGR gas flowing through the EGR passage,
The EGR system according to any one of claims 1 to 6, wherein the supply passage is connected to an upstream side of the EGR cooler in the EGR passage. An EGR method for recirculating a part of exhaust gas from an exhaust passage of an engine to an intake passage through an EGR passage,
The exhaust gas in the exhaust passage is brought into contact with the exhaust gas downstream of the exhaust passage and the absorbing liquid, and carbon dioxide contained in the exhaust gas is absorbed by the absorbing liquid.
Heating the absorption liquid that has absorbed the carbon dioxide to regenerate carbon dioxide contained in the absorption liquid,
An EGR method for supplying the regenerated carbon dioxide to the EGR passage.

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