JP5856772B2 - EGR device - Google Patents

Description

  The present invention relates to an EGR (exhaust gas recirculation) device that recirculates a part of exhaust gas from a combustion device such as an internal combustion engine into a combustion chamber for recombustion.

  Purifying the exhaust from the internal combustion engine to suppress the expansion of air pollution is an important issue, but as one of the systems (apparatus) for this purpose, a part of the exhaust from the internal combustion engine is returned to the combustion chamber. A so-called EGR (Exhaust Gas Recirculation) system is known for reducing the combustion temperature by reducing the combustion temperature and reducing the concentration (exhaust amount) of nitrogen oxide (hereinafter referred to as NOx) in the exhaust gas. ing.

  In such an EGR system, by cooling the EGR gas to be recirculated into the combustion chamber, the combustion temperature can be lowered, and thereby the NOx emission can be more effectively reduced.

  For this reason, for example, in the EGR system described in Patent Document 1, an EGR cooler that is a heat exchanger for cooling EGR gas is connected to an EGR passage that guides the EGR gas from the exhaust passage to the intake passage of the internal combustion engine. It has been done to intervene.

  In addition, since the expansion of the EGR gas is suppressed by providing the EGR cooler and lowering the EGR gas temperature, it is desired to increase the amount of EGR gas (exhaust gas recirculation amount) mixed in the intake air, that is, the EGR rate (= EGR This is also advantageous when there is a demand for further earning gas amount / (fresh air amount + EGR gas amount) × 100 (%)).

  Here, as a means for achieving further NOx reduction, it is conceivable to further cool the EGR gas. For example, the EGR gas is cooled from about 150 ° C. to 100 ° C. or less. In such a case, there is a high possibility that condensed water is generated from the cooled EGR gas.

  Since the EGR gas contains sulfur in the fuel, the condensed water contains sulfuric acid. Therefore, if the condensed water containing sulfuric acid adheres to or stays inside the EGR passage or the combustion chamber of the internal combustion engine, the internal combustion engine Corrosion, damage, etc. will be caused in each part of the engine (EGR passage, EGR valve, intake passage, combustion chamber, etc.). Furthermore, the combustion chamber of the internal combustion engine may suck in the parts (foreign matters) that have been corroded and peeled off. In such a case, the internal combustion engine may be damaged.

  In addition, since the combustion chamber of the internal combustion engine sucks in a large amount of condensed water, the internal combustion engine may be damaged by a so-called water hammer.

  As a technique for suppressing such a fear, for example, there are techniques described in Patent Document 1 to Patent Document 2.

JP 2007-064075 A JP 2003-004389 A

  The one described in Patent Document 1 is intended to cool the EGR gas by passing a part of the EGR passage through which the EGR gas flows through the intake passage to cool the EGR gas. It is configured to be able to be stored in the reservoir 170 via the flow path 150, or is provided with an on-off valve 160 that is opened and closed according to the weight of the condensed water and is automatically discharged to the outside.

  However, the one described in Patent Document 1 is a configuration in which a part of the EGR gas passage passes through the intake passage, so that the intake passage cross-sectional area is reduced, so that the intake resistance is increased and the output performance, fuel consumption performance, and the like are improved. There is a risk of adverse effects, and the configuration may be complicated and costly.

  Moreover, since the thing of patent document 1 will be provided with several components in an intake passage, when these parts are damaged, for example, the parts are sucked into a combustion chamber. Therefore, there is a high possibility that the internal combustion engine will be seriously damaged and the reliability is lowered.

  The one described in Patent Document 2 is a configuration in which a cooler through which cooling water flows is provided around the EGR passage, and the configuration becomes complicated and expensive, and the comparison is performed when further cooling of the EGR gas is performed. The fact is that no consideration has been given to the condensate generated in large quantities.

  The present invention has been made in view of such a conventional situation, and effectively collects condensed water generated by cooling of the EGR gas while maintaining a high level of reliability while having a simple and inexpensive configuration. An object of the present invention is to provide an EGR device that can be collected and stored in a storage unit, and that can effectively suppress corrosion, damage, and the like of each part of an internal combustion engine caused by condensed water.

For this reason, the present invention
An EGR device that recirculates a part of exhaust gas as EGR gas to a combustion chamber through an EGR passage,
An EGR cooler that cools the EGR gas is installed in the EGR passage,
An annular concave groove provided on the inner wall of the EGR passage on the downstream side of the EGR gas flow with respect to the EGR cooler, along a plane intersecting the EGR gas flow at a predetermined inclination angle so that the lower end thereof is on the downstream side of the EGR gas flow or A plurality of convex portions are provided, and the condensed water collecting portion that collects condensed water generated from the EGR gas is provided by the plurality of annular concave grooves or convex portions ,
The condensed water collected by the condensed water collecting part is accommodated in a storing part and stored.

In the present invention, a lower end of the concave groove at the most downstream side of the EGR gas flow of the plurality of annular concave grooves may be connected to an inlet portion of the storage portion .

In the present invention, an inlet portion of the storage portion is provided between the convex portion on the most downstream side of the EGR gas flow of the plurality of annular convex portions and the convex portion adjacent to the convex portion on the most downstream side. It can be characterized by being connected .

  In the present invention, the bottom of the inner wall of the EGR passage may be provided with a condensed water transport groove that is connected to the concave groove or the convex portion and transports the condensed water to the storage portion.

  ADVANTAGE OF THE INVENTION According to this invention, although it is a simple and cheap structure, the condensed water which generate | occur | produces with cooling of EGR gas can be collected effectively and can be stored in a storage part, maintaining reliability at a high level. It is possible to provide an EGR device that is configured to effectively suppress corrosion, damage, and the like of each part of the internal combustion engine caused by condensed water.

1 is a schematic overall configuration diagram schematically showing a configuration example of an internal combustion engine including an EGR device according to Embodiment 1 of the present invention. It is a side view (figure seen from the A arrow direction of Drawing 1) which expands and shows the condensed water collection part (spiral concave groove) of the EGR device concerning an example same as the above. It is a figure which shows another example of a structure of the condensed water collection part (annular concave groove) which concerns on an Example same as the above. It is a figure which shows another structural example of the condensed water collection part (helical convex part) which concerns on an Example same as the above. It is a figure which shows another example of a structure of the condensed water collection part (annular convex part) which concerns on an Example same as the above. It is a figure which shows another example of a structure of the condensed water collection part (a spiral concave groove + condensed water conveyance groove | channel) which concerns on an Example same as the above. It is a figure which shows another example of a structure of the condensed water collection part (annular concave groove | channel + condensed water conveyance groove | channel) which concerns on an Example same as the above.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

  As shown in FIG. 1, in the internal combustion engine 1 according to Example 1 of the present embodiment, outside air (fresh air) is drawn through an air cleaner or the like (not shown). Then, after being guided to a compressor (impeller) 3A of the supercharger 3 and compressed to a predetermined level, it is cooled to a predetermined level via an intercooler 4 interposed in the intake passage 2 and is put into a combustion chamber (cylinder) 5. Led.

  The gas after combustion discharged from the combustion chamber 5 is led to an exhaust passage (exhaust manifold portion) 7 through an exhaust port (not shown) opened to the combustion chamber 5, and then the supercharger 3. After supplying rotational energy to the exhaust turbine 3B, the exhaust gas is purified by receiving predetermined processing in an exhaust treatment device (not shown) (an oxidation catalyst, a NOx reduction catalyst, a diesel particulate filter, etc.) disposed downstream of the exhaust passage 6. And discharged into the atmosphere.

  Here, in this embodiment, part of the gas after combustion (that is, the exhaust gas) is guided again to the combustion chamber 5 together with the intake air (fresh air), thereby reducing the combustion temperature and reducing NOx. An apparatus 100 is provided.

  An EGR device (system) 100 according to the present embodiment includes an EGR passage (exhaust gas recirculation passage) 101 communicated with an exhaust passage (exhaust manifold portion) 7, and the EGR passage 101 includes the EGR passage 101. An EGR cooler 110 for intercooling the flowing exhaust gas (EGR gas: recirculation exhaust gas) is provided.

  An EGR valve 120 is interposed in the vicinity of the connection portion between the EGR passage 101 and the intake passage 2, and a part of the exhaust flowing through the exhaust passage 7 is opened to a predetermined opening degree in a predetermined operation state. As EGR gas, it is led to the intake passage 2 of the internal combustion engine 1 while being cooled by the EGR cooler 110.

  The EGR cooler 110 functions as a heat exchanger, and is configured to be able to cool EGR gas flowing in an elongated tubular heat transfer tube in the EGR cooler 110 by a cooling medium such as water or air.

  Here, in order to further promote NOx reduction, when the EGR gas is cooled from about 150 ° C. to 100 ° C. or less, there is a high possibility that condensed water is generated from the cooled EGR gas. In this embodiment, the generated condensed water can be effectively collected and the condensed water can be reliably stored, so that corrosion, damage, etc. of each part of the internal combustion engine caused by the condensed water can be prevented. It comprised so that it might suppress more effectively.

  That is, the EGR passage 101 on the downstream side of the EGR cooler 110 is provided with a condensed water collecting unit 200 as condensed water collecting means.

  As shown in FIG. 2 in an enlarged manner, the condensed water collecting unit 200 has a concave groove formed in a spiral shape along the EGR gas flow direction on the inner wall surface of the EGR passage 101 on the downstream side of the EGR cooler 110. 210 is included.

  A communication passage 220 that opens toward the bottom of the EGR passage 101 is provided near the downstream end of the EGR gas flow of the concave groove 210, and the downstream end of the EGR gas flow of the concave groove 210 is provided via the communication passage 220. The vicinity communicates with a condensed water storage tank 230 which is a condensed water storage unit. The communication passage 220 is preferably branched downward from the EGR passage 101 in the direction of gravity so that the condensed water can be collected well and the collected condensed water does not flow backward.

  In the present embodiment having such a configuration, the EGR gas flowing through the EGR passage 101 is cooled by the EGR cooler 110 from the conventional 150 ° C. level to a level of 100 ° C. or lower. Then, there is a high possibility that condensed water is generated from the cooled EGR gas, but the moisture in the EGR gas is cooled and condensed on the wall surface of the EGR passage 101 after passing through the EGR cooler 110, and the inside of the EGR passage 101 Adhere to the wall. Since the outer wall of the EGR passage 101 is in contact with the outside air, the wall surface of the EGR passage 101 tends to be at a low temperature.

  The condensed water adhering to the inner wall surface of the EGR passage 101 is moved downward by gravity, and is caused to flow downstream of the EGR gas flow by the EGR gas flow, thereby along the inner wall surface of the EGR passage 101. The flow is collected in the concave groove 210 provided on the inner wall surface of the EGR passage 101.

  The condensed water collected in the concave groove 210 is affected by the flow of the EGR gas, and flows along the spiral concave groove 210 or flows along the bottom of the inner wall of the EGR passage 101, so that the communication passage It reaches the opening 220 and is accommodated and stored in the condensed water storage tank 230 via the communication passage 220.

  Therefore, according to the present embodiment, the condensed water collecting unit 200 provided on the inner wall of the EGR passage 101 can efficiently collect the condensed water, so that the EGR valve 120, the EGR passage 101, and the intake passage 2 can be collected. And corrosion of the combustion chamber 5 and the like can be suppressed. In addition, since the condensed water can be stored in the condensed water storage tank 230, the combustion chamber of the internal combustion engine can be prevented from sucking a large amount of condensed water, and the internal combustion engine can be controlled by a so-called water hammer. Damage and the like can be suppressed.

  That is, according to the present embodiment, the EGR gas can be cooled while maintaining a high level of reliability as a configuration in which parts are not arranged in the EGR passage or the intake passage as much as possible while being a simple and inexpensive configuration. Since the condensate generated along with the condensate can be effectively collected and stored in the reservoir, EGR can effectively suppress corrosion and damage of each part of the internal combustion engine caused by the condensate. An apparatus can be provided.

  In this embodiment, the condensed water collecting unit 200 has been described as the concave groove 210 provided in a spiral shape. However, the present invention is not limited to this, and for example, a plurality of annular concave shapes as shown in FIG. It can also be set as the structure which arranged the groove | channel 211 in parallel.

  That is, it is provided on the inner wall surface of the EGR passage 101, collects condensed water generated on the inner wall surface of the EGR passage 101 in a concave groove, and communicates the collected condensed water using EGR gas flow or gravity. As long as the opening of the passage 220 can be accommodated in the condensed water storage tank 230, it can be adopted.

  Here, the inclination angle of the plurality of annular concave grooves 211 with respect to the longitudinal direction of the EGR passage 101 is not particularly limited, and for example, a direction substantially perpendicular to the longitudinal direction of the EGR passage 101 (vertical in FIG. 3). (Direction).

  Furthermore, in the present embodiment, the condensed water collecting unit 200 can be configured as a convex portion 212 provided in a convex shape.

  That is, as shown in FIG. 4, a convex portion 212 that protrudes from the inner wall surface of the EGR passage 101 and is provided in a convex shape is provided, and condensed water generated on the inner wall surface of the EGR passage 101 is formed at the convex portion 212. It is also possible to adopt a configuration in which the condensate is collected by damming, and the collected condensed water is guided to the opening of the communication passage 220 using the EGR gas flow or gravity and is stored in the condensed water storage tank 230.

  A notch groove 212A that functions as a condensed water transport groove is provided in the vicinity of the bottom of the inner wall of the EGR passage 101 of the convex portion 212 so that the condensed water easily flows along the longitudinal direction of the EGR passage 101. Can do.

  The convex portion 212 can be formed in a spiral shape in the direction along the EGR gas flow as shown in FIG. 4, but as shown in FIG. 5, a plurality of annular convex portions 213 are formed. It can also be set as the structure arranged in parallel.

  Also in this case, as shown in FIG. 5, it functions as a condensed water transport groove so that the condensed water easily flows along the longitudinal direction of the EGR passage 101 near the bottom of the inner wall of the EGR passage 101 of the convex portion 213. A notch groove 213A can be provided.

  Further, as shown in FIG. 6, it functions as a condensed water carrying groove so that the condensed water easily flows along the longitudinal direction of the EGR passage 101 in the vicinity of the bottom of the inner wall of the EGR passage 101 of the concave groove 210 provided in a spiral shape. The groove part 210A to be formed can be provided.

  Further, as shown in FIG. 7, a groove portion 211 </ b> A that functions as a condensed water transport groove so that the condensed water easily flows along the longitudinal direction of the EGR passage 101 near the inner wall bottom portion of the EGR passage 101 of the plurality of concave grooves 211. Can be provided.

  By the way, a drain valve for discharging the collected and collected condensed water can be provided at the bottom of the condensed water storage tank 230. Further, an adsorbent that adsorbs and holds the condensed water collected and recovered can be provided inside the condensed water storage tank 230.

  After the EGR passage 101 merges with the intake passage 2, the acid concentration (for example, sulfuric acid concentration) of the gas is lowered by mixing with fresh air, so that the acid dew point (temperature at which sulfuric acid is condensed) is lowered. Condensed water is less likely to be generated. For this reason, the condensed water collecting unit 200 is preferably provided in the EGR passage 101 on the downstream side of the EGR gas flow of the EGR cooler 110 and upstream of the joining portion with the intake passage 2. However, the present invention is not limited to this, and depending on the specifications and usage environment of the internal combustion engine 1 and the generation mode of the condensed water, the condensed water collecting part 200 is disposed in another part of the EGR passage 101. can do.

  By the way, the condensed water collection part 200 can also be arrange | positioned in multiple steps along the flow direction of EGR gas.

  In the present embodiment, the EGR passage 101 is provided with the condensed water collecting unit 200. However, the present invention is not limited to this, and the EGR passage in the EGR cooler 110 is condensed in the EGR passage portion. It is also possible to adopt a configuration in which the water collection unit 200 is provided.

  Further, the internal combustion engine according to the present invention is not particularly limited. For example, the present invention is applicable not only to a vehicle mounted on a vehicle but also to a stationary type, and a diesel engine, a gasoline engine, The present invention is applicable to an internal combustion engine that burns other fuels regardless of the combustion method.

  Further, although the case where sulfur is contained in the fuel has been described, the present invention is not limited to this, and the present invention can be applied even to a fuel from which the sulfur content has been removed. However, it is beneficial in that corrosion and damage to the internal combustion engine due to moisture can be effectively suppressed.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake passage 3 Supercharger 3A Compressor 3B Exhaust turbine 4 Intercooler 5 Combustion chamber 6 Exhaust passage 7 Exhaust passage 100 EGR device 101 EGR passage 110 EGR cooler 120 EGR valve 200 Condensate collecting part 210 Concave groove (spiral) Status)
210A Groove (condensate transport groove)
211 concave groove (annular)
211A Groove (condensate transport groove)
220 Communication passage 230 Condensate storage tank (storage part)
212 Convex part (spiral)
212A Notch groove (Condensate transport groove)
213 Convex part (annular)
213A Notch groove (condensate transport groove)

Claims (4)

An EGR device that recirculates a part of exhaust gas as EGR gas to a combustion chamber through an EGR passage,
An EGR cooler that cools the EGR gas is installed in the EGR passage,
An annular concave groove provided on the inner wall of the EGR passage on the downstream side of the EGR gas flow with respect to the EGR cooler, along a plane intersecting the EGR gas flow at a predetermined inclination angle so that the lower end thereof is on the downstream side of the EGR gas flow or A plurality of convex portions are provided, and the condensed water collecting portion that collects condensed water generated from the EGR gas is provided by the plurality of annular concave grooves or convex portions ,
An EGR device characterized in that the condensed water collected by the condensed water collecting unit is stored in a storing unit. 2. The EGR device according to claim 1 , wherein lower ends of the concave grooves at the most downstream side of the EGR gas flow of the plurality of annular concave grooves are connected to an inlet portion of the storage portion . An inlet portion of the storage portion is connected between a convex portion at the most downstream side of the EGR gas flow of the plurality of annular convex portions and a convex portion adjacent to the convex portion at the most downstream side. The EGR device according to claim 1 . The concave groove or formed at the lower end of the convex portion, EGR device according to any one of claims 1 to 3, characterized in that condensed water transport groove for transporting condensed water to the reservoir portion is provided .

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