JP6370147B2 - EGR device - Google Patents

Description

  The present invention relates to an EGR device capable of collecting and removing condensed water generated by cooling of EGR gas.

  Conventionally, in an automobile engine or the like, by extracting a part of the exhaust from the exhaust side and returning it to the intake side, by suppressing the combustion of fuel in the engine with the exhaust returned to the intake side and lowering the combustion temperature So-called exhaust gas recirculation (EGR) is performed to reduce the generation of NOx (nitrogen oxide).

  Normally, in the case of an EGR device that performs this type of exhaust gas recirculation, an EGR pipe is used between an appropriate position of the system path from the exhaust manifold to the exhaust pipe and an appropriate position of the system path from the intake pipe to the intake manifold. Connected to recirculate exhaust through the EGR pipe.

  At this time, if the exhaust gas (EGR gas) recirculated to the engine is cooled in the middle, the temperature of the exhaust gas decreases and the volume of the exhaust gas decreases, thereby effectively reducing the combustion temperature without significantly reducing the engine output. Since NOx generation can be reduced, an EGR cooler for cooling the recirculated exhaust gas is generally provided in the middle of the system for recirculating the exhaust gas to the engine.

  That is, if the EGR gas is cooled by such an EGR cooler, the temperature of the exhaust itself is lowered, the volume is reduced, the density is increased, and the charging efficiency into the combustion chamber of the engine is increased. In this way, more exhaust can be introduced without significantly affecting the output of the engine.

  In such an EGR cooler, there is a problem that condensed water is generated by cooling exhaust gas containing water vapor generated by fuel combustion to a dew point or lower. If condensate stays in the EGR system or intake system, the EGR system narrows and pressure loss increases, EGR cannot be performed efficiently, the intercooler is blocked, and a large amount of water enters the engine. This may lead to various problems such as damage caused by water hammer.

  In the future, it is expected that it will be necessary to further enhance the cooling capacity of the EGR cooler and improve the EGR efficiency in accordance with exhaust gas regulations that will become increasingly strict. When the cooling capacity of the EGR cooler is strengthened, it is considered that condensed water is likely to be generated in the EGR cooler. For this reason, means for separating and removing the condensed water generated in the EGR system path from the EGR gas is provided. is necessary.

  As an apparatus for separating and removing condensed water generated in the EGR system path, for example, apparatuses described in Patent Documents 1 to 4 have been proposed.

JP 2010-25034 A JP 2013-29081 A JP 2010-222980 A JP 2012-188944 A

  However, in the EGR devices described in Patent Documents 1 and 2 above, the collection of condensed water is performed by cooling the exhaust gas at the tube wall of the EGR pipe, and the condensed water naturally condenses on the tube wall. Condensed water cannot be collected sufficiently, and it is required to collect condensed water more efficiently. Further, in the EGR device described in Patent Documents 3 and 4, exhaust gas collides with a wall or a plate-like mesh as a means for collecting condensed water, so that the pressure loss of EGR gas increases. There's a problem.

  In addition, as an apparatus for separating and removing condensed water generated in the EGR system path, a cyclone type gas-liquid separation apparatus may be installed in the middle of the EGR system path in addition to the apparatuses described in Patent Documents 1 to 4 above. Although it is conceivable, there is also a problem that the pressure loss increases in this case.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an EGR device that can efficiently collect condensed water generated by cooling of the EGR gas while suppressing pressure loss of the EGR gas.

The present invention is an EGR device that connects an exhaust side and an intake side of an engine by an EGR system path, and cools EGR gas by an EGR cooler provided in the EGR system path, and is provided downstream of the EGR cooler. A part of the EGR pipe is a condensed water suction part having a drain hole formed in the tube wall of the EGR pipe, and a condensed water absorber is provided so as to surround the outer peripheral surface of the condensed water suction part. Rutotomoni comprising a condensate separator which is configured to a vent hole extracting condensed water in the EGR gas to the condensed water absorber, comprising a swirl flow generating device to the EGR system path upstream of said condensate separator, revolving round An EGR device characterized in that a flow generator and the condensate separator are arranged at an interval, and an EGR system path between the swirl generator and the condensate separator is configured as a running portion. It depends on.

  Thus, the condensed water can be efficiently separated from the EGR gas by the capillary phenomenon of the condensed water absorber while suppressing the pressure loss.

Further, is provided with the swirling flow generator to the EGR system path upstream of said condensate separator, the centrifugal force of the swirling flow formed in the EGR gas may separate the condensate from the more efficiently EGR gas.

Furthermore, the swirl flow generator and the condensate separator are arranged at an interval, and the EGR system path between the swirl generator and the condensate separator is configured as a running part . The swirl flow formed in the EGR gas is stabilized while flowing through the runner, and the condensed water can be more efficiently separated from the EGR gas.

  According to the EGR device of the present invention, it is possible to achieve an excellent effect that the condensed water generated by the cooling of the EGR gas can be efficiently collected while suppressing the pressure loss of the EGR gas.

It is the schematic which shows the whole structure of the Example of this invention. It is the schematic which expands and shows the internal structure of the principal part of the Example of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an example of the form of an EGR apparatus according to the embodiment of the present invention. In the figure, reference numeral 1 denotes an engine equipped with a turbocharger 2, and intake air 4 guided from an air cleaner 3 is sent to a compressor 2 a of the turbocharger 2 through an intake pipe 5 and pressurized by the compressor 2 a. 4 is sent to the intercooler 6 to be cooled, and the intake air 4 is further guided from the intercooler 6 to the intake manifold 7 to each cylinder 8 of the engine 1 (FIG. 1 illustrates the case of in-line four cylinders). The exhaust 9 discharged from each cylinder 8 of the engine 1 is sent to the turbine 2b of the turbocharger 2 through the exhaust manifold 10, and the exhaust pipe 11 is driven after the turbine 2b is driven. To be sent out.

  The exhaust manifold 10 and the intake pipe 5 in the vicinity of the inlet of the intake manifold 7 are connected by a high-pressure loop (EGR system path) 12, and a part of the exhaust 9 from the exhaust manifold 10 is EGR gas via the high-pressure loop 12. It is extracted as 9a and can be recirculated to the intake pipe 5 near the inlet of the intake manifold 7.

  The exhaust pipe 11 downstream of the turbine 2b of the turbocharger 2 and the intake pipe 5 upstream of the compressor 2a of the turbocharger 2 are connected by a low-pressure loop (EGR system path) 13, and the low-pressure loop 13, a part of the exhaust gas 9 is extracted as EGR gas 9 a from the exhaust pipe 11 downstream of the turbine 2 b of the turbocharger 2 and can be recirculated to the intake pipe 5 upstream of the compressor 2 a of the turbocharger 2. is there.

  Here, the high-pressure loop 12 and the low-pressure loop 13 include EGR valves 14 and 15 whose opening degrees can be adjusted so that the amount of recirculation of the exhaust gas 9 can be appropriately adjusted, and the recirculated EGR gas 9a as cooling water. EGR coolers 16 and 17 that are cooled by heat exchange are respectively provided.

  Thus, in the engine 1 of the present embodiment, the low pressure loop 13 is used in addition to the high pressure loop 12 as an EGR system path connecting the exhaust side and the intake side of the engine 1. This is because if a large amount of EGR gas 9a is introduced only by a general high-pressure loop 12, the power recovery in the turbine 2b is reduced and the supercharging performance is lowered. When the EGR gas 9a having a relatively low exhaust temperature is recirculated and cooled by using the low-pressure loop 13 together, there is a concern that a large amount of condensed water is generated in the EGR cooler 17 of the low-pressure loop 13, and the condensed water These measures are indispensable.

  Therefore, in the present embodiment, the condensed water collection for collecting the condensed water generated in the EGR gas 9 a by the cooling in the EGR cooler 17 in the low pressure loop (EGR system path) 13 downstream of the EGR cooler 17. A device 18 is installed.

  As shown in an enlarged view in FIG. 2, the condensed water collecting device 18 includes a swirling flow generator 19 installed in a low pressure loop (EGR line) 13 downstream of the EGR cooler 17, and a downstream side of the swirling flow generator 19. And a condensed water separator 20 installed at a predetermined interval.

  The swirl flow generator 19 is formed, for example, by arranging a spiral body, for example, a metal twist tape 22 inside an EGR pipe 21 forming the EGR system path 13. The EGR gas 9a passing therethrough is given a flow rotating in the circumferential direction of the EGR pipe 21 by a spiral body (twisted tape) 22 and flows downstream as a swirling flow. The swirling flow generator 19 is not limited to the above-described configuration as long as it can form a swirling flow in the EGR gas 9a flowing through the EGR system path 13.

  The condensate separation device 20 includes a housing 23 installed so as to cover a part of the EGR pipe 21 forming the EGR system path 13 from the outside, and many of the EGR pipes 21 inside the housing 23 are arranged on the pipe wall. A condensed water absorber 25 is provided so as to be formed as a condensed water suction portion 24 having a water drain hole 24 a and surrounding the outer peripheral surface of the condensed water suction portion 24. As the condensed water absorber 25, for example, a porous material having heat resistance and capable of sucking condensed water by a capillary phenomenon, such as glass wool, is used.

  A drain pipe 26 for draining the condensed water collected inside the housing 23 from below is attached at an appropriate position below the housing 23, and the drainage from the drain pipe 26 is in the middle of the drain pipe 26. It is controlled by opening and closing the drain valve 27 installed.

  Next, the operation of this embodiment will be described.

  When exhaust gas recirculation is performed by the low pressure loop 13 during operation of the engine 1, if the EGR valve 15 of the low pressure loop 13 is opened, a part of the exhaust gas 9 flowing through the exhaust pipe 11 becomes EGR gas 9 a as the low pressure loop. 13 is extracted and supplied to the intake pipe 5 upstream of the compressor 2 a of the turbocharger 2. The EGR gas 9a flowing through the low-pressure loop (EGR system path) 13 is cooled in an EGR cooler 17 provided in the middle of the EGR system path 13 so that the temperature is lowered and the density is increased. At this time, when the temperature of the EGR gas 9a falls below the dew point, condensed water is generated as water droplets in the EGR gas 9a.

  The EGR gas 9a containing condensed water flows downstream of the EGR cooler 17, and turns into a swirl flow by passing through a swirl flow generator 19 provided in the EGR system passage 13 downstream of the EGR cooler, and further flows downstream. To go.

  Here, as described above, the swirling flow generator 19 and the condensed water separator 20 are installed in the EGR system path 13 at a predetermined interval. For this reason, the EGR gas 9a that has passed through the swirling flow generator 19 stabilizes the flow as a swirling flow while flowing through the distance to the condensed water separator 20. In other words, the EGR system path 13 between the swirling flow generator 19 and the condensed water separator 20 functions as the run-up portion 28 for the EGR gas 9a.

  Due to the swirl flow formed by the EGR gas 9 a, the condensed water contained as water droplets in the EGR gas 9 a is blown off to the radially outer side of the EGR pipe 21 by centrifugal force and adheres to the inner wall of the EGR pipe 21. And it flows along the inner wall of the EGR pipe 21 downstream according to the flow of the EGR gas 9a. And when it reaches the condensate suction part 24 of the condensate separator 20, it is absorbed by the condensate absorber 25 from the drain hole 24 a formed in the tube wall of the EGR pipe 21 by capillary action.

  The condensed water absorbed by the condensed water absorber 25 is collected in the housing 23 and then drained from the drain pipe 26 by opening the drain valve 27 as appropriate.

  Thus, according to this embodiment, a part of the EGR pipe 21 downstream of the EGR cooler 17 is used as the condensed water suction portion 24 having a drain hole 24a formed in the tube wall of the EGR pipe 21, and the A condensed water absorber 25 is provided so as to surround the outer peripheral surface of the condensed water suction part 24, and a condensed water separator 20 configured to extract condensed water in the EGR gas 9a from the drain hole 24a to the condensed water absorber 25 is provided. Therefore, the condensed water can be efficiently separated from the EGR gas 9a by the capillary phenomenon of the condensed water absorber 25 while suppressing the pressure loss.

  Further, according to the present embodiment, since the swirling flow generating device 19 is provided in the EGR system path 13 upstream of the condensed water separating device 20, the swirling flow centrifugal force formed in the EGR gas 9a is more efficient. The condensed water can be separated from the EGR gas 9a.

  Furthermore, according to the present embodiment, the swirling flow generator 19 and the condensed water separator 20 are arranged at an interval, and the EGR path 13 between the swirling flow generator 19 and the condensed water separator 20 is run up. Since it comprises as the part 28, the swirl | vortex flow formed in the EGR gas 9a is stabilized while flowing through the runaway part 28, and condensed water can be more efficiently separated from the EGR gas 9a.

  Therefore, according to the EGR device of the present embodiment, the condensed water generated by cooling the EGR gas can be efficiently collected while suppressing the pressure loss of the EGR gas.

  The EGR device of the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, a condensate collecting device is installed on the downstream side of the EGR cooler in the middle of the low-pressure loop. However, it goes without saying that various modifications can be made without departing from the spirit of the present invention, such as being installed downstream of the EGR cooler in the middle of the high-pressure loop.

1 Engine 9a EGR gas 13 EGR system (low pressure loop)
17 EGR cooler 19 Swirl generator 20 Condensate separator 21 EGR pipe 24 Condensate inlet 24 a Drain hole 25 Condensate absorber 28 Advancing part

Claims (1)

An EGR device that connects an exhaust side and an intake side of an engine by an EGR system path and cools EGR gas by an EGR cooler provided in the EGR system path,
A part of the EGR pipe downstream of the EGR cooler is used as a condensed water suction portion having a drain hole formed in the tube wall of the EGR pipe, and the condensed water absorber is surrounded by the outer peripheral surface of the condensed water suction portion. wherein the water drain hole from comprises a condensate separator device configured to extract the condensed water in the EGR gas to the condensed water absorber Rutotomoni, swirl flow generating device to the EGR system path upstream of said condensate separator The swirling flow generator and the condensate separator are arranged at an interval, and the EGR system path between the swirl generator and the condensate separator is configured as a running part. A featured EGR device.

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