JP2015129619A - Engine egr cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine EGR cooler capable of realizing excellent cooling efficiency with a simple configuration.SOLUTION: An EGR cooler 22 comprises: a gas cooling passage 25 provided in parallel to a water feed passage 15; a plurality of first ribs 35 protruding from an inner wall of the gas cooling passage 25 and extending from upstream to downstream of the gas cooling passage 25; and a plurality of second ribs 36 protruding from the inner wall of the gas cooling passage 25 and extending from upstream to downstream of the gas cooling passage 25 so as to face the first ribs 35 to be spaced apart from the first ribs 35 at very small intervals.

Description

  The present invention relates to an engine EGR cooler that recirculates a part of exhaust gas as EGR gas to an intake system.

  Conventionally, in an engine, an exhaust gas recirculation (EGR) device that recirculates a part of exhaust gas to an intake system has been widely used for the purpose of reducing NOx emissions and improving fuel consumption. The EGR device is generally provided with an EGR cooler for cooling high-temperature exhaust gas (EGR gas) discharged from the engine. As the EGR cooler, many gas-liquid heat exchange type EGR coolers that cool the gas EGR gas with engine cooling water are employed.

  As a technique for improving the cooling efficiency of this type of EGR cooler, for example, Patent Document 1 discloses a corrugate having a substantially rectangular channel shape in a flat heat transfer tube constituting a so-called shell-and-tube heat exchanger. A technique is disclosed in which fins are provided and a plurality of slit-shaped notches are provided on corrugated fins.

JP 2008-14466 A

  However, since the technique disclosed in Patent Document 1 described above needs to incorporate a separate corrugated fin in the heat transfer tube, the structure is complicated.

  In addition, as in the technique disclosed in Patent Document 1 described above, in a configuration in which a slit-like cutout is simply provided on a corrugated fin, the flow of EGR gas between small flow paths partitioned by the corrugated fin. However, since it is performed only locally, it may be difficult to improve the cooling efficiency sufficiently.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an EGR cooler for an engine that can achieve good cooling efficiency with a simple configuration.

  An EGR cooler for an engine according to one aspect of the present invention is provided integrally with a cooling water passage, and has an upstream side communicating with an exhaust system and a downstream side communicating with an intake system, and an inner wall portion of the gas cooling passage A plurality of first ribs extending from the upstream side to the downstream side of the gas cooling passage and protruding from an inner wall portion of the gas cooling passage so as to face the first rib with a slight gap therebetween. And a plurality of second ribs extending from the upstream side to the downstream side of the gas cooling passage.

  According to the EGR cooler of the engine of the present invention, good cooling efficiency can be realized with a simple configuration.

Schematic configuration diagram of the engine The perspective view which looked at the water passage which constitutes the cooling water passage of the engine from the back side of the cylinder block Plan view showing the main part of the water passage, partially broken Sectional view along line IV-IV in FIG. Sectional drawing which follows the VV line of FIG. Cross-sectional perspective view of essential parts of water passage and EGR cooler Cross-sectional exploded perspective view of the main part of the water passage and EGR cooler

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of an engine, FIG. 2 is a perspective view of a water passage constituting the cooling water passage of the engine as viewed from the back side of the cylinder block, and FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is a sectional view taken along line V-V in FIG. 3, and FIG. The principal part sectional perspective view of a passage and an EGR cooler, FIG. 7 is a principal part sectional perspective view of a water passing passage and an EGR cooler.

  In FIG. 1, reference numeral 1 denotes an engine, and in this embodiment, a horizontally opposed four-cylinder engine is shown. The cylinder head 2 of the engine 1 is formed with an intake port 2a for each cylinder. Each of these intake ports 2 a is gathered via an intake manifold 4, and its gathering end communicates with an air chamber 5 a formed downstream of the intake pipe 5. An air cleaner 10 is interposed on the upstream side of the intake pipe 5, and an electronically controlled throttle valve 11 is interposed in the middle of the intake pipe 5.

  An injector 13 is disposed at the downstream end of the intake manifold 4 communicating with each intake port 2a. Further, a spark plug 14 is attached to the cylinder head 2 with its tip facing the combustion chamber of each cylinder.

  On the other hand, an exhaust pipe 7 is communicated with an exhaust port 2 b formed in the cylinder head 2 via an exhaust manifold 6. The exhaust pipe 7 has an exhaust purification catalyst 8 interposed at the upstream end and a muffler 9 attached to the downstream end.

  Also, an exhaust gas recirculation (EGR) passage 21 constituting the EGR device 20 extends from the pipe line of the exhaust manifold 6 communicating with the exhaust port 2b of the # 3 cylinder, for example, among the four cylinders, to the air chamber 5a. It is communicated. In the middle of the EGR passage 21, an EGR cooler 22 for cooling the EGR gas is interposed, and an EGR valve 23, which is a flow rate control valve for adjusting the EGR amount, is interposed. The EGR cooler 22 of the present embodiment is a gas-liquid heat exchange type EGR cooler, and is provided integrally with, for example, a cooling water passage (so-called water passage) 15 that communicates the left and right banks of the cylinder block 3. .

  More specifically, as shown in FIG. 2, the water transfer passage 15 of the present embodiment is fixed to the upper rear side of the cylinder block 3, for example. The water passage 15 is constituted by a flat pipe line having a substantially rectangular tube shape made of a cast product made of an aluminum alloy having good thermal conductivity, for example. The left and right ends of the water passage 15 are formed so as to gradually reduce the cross-sectional area (see FIG. 3), and the water in each bank of the cylinder block 3 is formed on the bottom side of the left and right ends thus formed. A communication port 15a communicating with the jacket 3a is opened (see FIGS. 1 and 2).

  Further, for example, a main circulation passage 16 for circulating cooling water to a radiator (not shown) is connected to the left end portion of the water passing passage 15, and cooling water is connected to a heater core (not shown) at the right end portion. A sub-circulation passage 17 is connected to circulate in the air. Further, in the middle of the water transfer passage 15, a bottom bypass passage 18 for bypassing the radiator and circulating the cooling water in a cold state or the like is communicated.

  As shown in FIGS. 4 to 7, a gas cooling passage 25 constituting the EGR cooler 22 is provided on the bottom surface side of the water transfer passage 15. The gas cooling passage 25 extends, for example, along the water transfer passage 15, and includes a first passage member 27 including a groove portion recessed in the outer wall portion on the bottom surface side of the water transfer passage 15, and water. The second passage member 28, which is formed of a casting product separate from the transfer passage 15, is joined to each other.

  For example, as shown in FIGS. 2 to 4, an upstream side connection pipe 30 penetrating the inside and the outside of the water passage 15 is communicated with the right end that is the upstream side of the gas cooling passage 25. Is connected to the upstream passage 21a of the EGR passage 21 whose upstream side communicates with the exhaust manifold 6.

  On the other hand, for example, as shown in FIGS. 3 and 6, a downstream side connection pipe 31 penetrating the inside and the outside of the water passage is communicated with the left end on the downstream side of the gas cooling passage 25. The downstream side passage 21b of the EGR passage 21 whose downstream side communicates with the air chamber 5a is connected. Further, a valve holding hole 32 is interposed between the gas cooling passage 25 and the downstream side connecting pipe 31, and the EGR valve 23 (see FIG. 1) is held in the valve holding hole 32. Then, by adjusting the opening degree of the EGR valve 23, the amount of EGR recirculated from the exhaust system to the intake system is adjusted.

  Further, a plurality of first ribs 35 having a ridge shape project from the inner wall portion of the first passage member 27 (that is, the outer wall portion of the water transfer passage 15). These first ribs 35 are integrally formed, for example, when the water passage 15 is cast (that is, when the first passage member 27 is cast), and from the upstream side to the downstream side of the gas cooling passage 25. Has been extended.

  Further, a plurality of second ribs 36 having a ridge shape project from the inner wall portion of the second passage member 28. These second ribs 36 are integrally formed when the second passage member 28 is cast, and are downstream from the upstream side of the gas cooling passage 25 so as to face the first ribs 35 with a slight gap therebetween. It extends to the side.

  Here, the distance D1 between the first and second ribs 35 and 36 facing each other is set, for example, at a distance in the vicinity of a limit value that can be accurately and stably processed with respect to a cast product. Is set to an interval of around D1 = 1 mm. However, the distance D2 between the first and second ribs 35 and 36 in the upstream end region (right end region) and the downstream end region (left end region) of the gas cooling passage 25 is relative to D1. A wide interval is set, and specifically, D2 = 3 mm or more.

  That is, the first and second ribs 35 and 36 are spaced over the entire region from the upstream side to the downstream side of the gas cooling passage 25, and the interval D is basically set to a minute interval D1. However, only the upstream end region and the downstream end region of the gas cooling passage 25 are set to an interval D2 that is relatively wider than the minute interval D1.

  For example, as shown in FIGS. 3, 5, and 7, in the side portion in the arrangement direction of the first and second ribs 35, 36, from the inner wall portion of the gas cooling passage 25, the vertical direction (that is, the first , A plurality of third ribs 37 extending in a direction substantially orthogonal to the extending direction of the second ribs 35 and 36 are provided. These third ribs 37 are constituted by, for example, a series of ribs formed from the first passage member 27 to the second passage member 28 (see FIG. 5), and the first and second ribs 35 and 36 are formed. It is provided at predetermined intervals in the middle region of the gas cooling passage 25 where the interval is set to the minute interval D1 (see FIG. 3).

In such a configuration, when a part of the exhaust gas (EGR gas) discharged from each combustion chamber to the exhaust manifold 6 is introduced into the gas cooling passage 25 through the upstream passage 21 a of the EGR passage 21, EGR The gas is distributed in each small passage 25 a defined by the first and second ribs 35 and 36 in the upstream end region of the gas cooling passage 25. At this time, since the distance D2 between the first and second ribs 35 and 36 in the upstream end region is set to be relatively wider than the distance D1 in the midway region, the upstream end in the gas cooling passage 25 is set. The partial region functions as an air chamber, and the EGR gas can be efficiently distributed in each small passage 25a without generating excessive flow resistance with respect to the EGR gas introduced from the upstream passage 21a.

  Further, the EGR gas distributed to the small passages 25a in the upstream end region of the gas cooling passage 25 flows through the gas cooling passages 25 (the small passages 25a). , 36 and so on. At this time, due to a pressure difference between the small passages 25a, a part of the EGR gas moves between the adjacent small passages 25a through the gap between the first and second ribs 35 and 36. In this case, in particular, in the midway region where the interval between the first and second ribs 35 and 36 is set to the minute interval D1, the EGR gas moves between the adjacent small passages 25a at a relatively high flow rate, and is small. After stirring the EGR gas in the passage 25a, it collides with the first and second ribs 35 and 36. Thereby, heat exchange between the first and second ribs 35 and 36 and the EGR gas is promoted, and a good cooling efficiency of the EGR gas is realized.

  In addition, when a part of the EGR gas collides with the third rib 37, a turbulent flow of the EGR gas is generated in the gas cooling passage 25, and this also promotes the movement of the EGR gas between the small passages 25a. The Therefore, heat exchange between the first and second ribs 35 and 36 and the EGR gas is further promoted, and a good cooling efficiency of the EGR gas is realized.

  Further, the EGR gas that has flowed through the middle region of the gas cooling passage 25 and reached the downstream end region flows out through the EGR valve 23 into the downstream passage 21b. At this time, the interval D2 between the first and second ribs 35 and 36 in the downstream end region is set to be relatively wider than the interval D1 in the midway region, so the downstream end in the gas cooling passage 25 The partial area functions as an air chamber, and the EGR gas distributed to each small passage 25a can be efficiently collected and guided to the EGR valve 23.

  According to such an embodiment, a plurality of gas cooling passages 25 provided alongside the water passage 15 and a plurality of protrusions protruding from the inner wall portion of the gas cooling passage 25 and extending from the upstream side to the downstream side of the gas cooling passage 25. A plurality of second ribs 35 project from the inner wall portion of the gas cooling passage 25 and extend from the upstream side to the downstream side of the gas cooling passage 25 so as to face the first rib 35 with a slight gap therebetween. By configuring the EGR cooler 22 with the ribs 36, good cooling efficiency of the EGR gas can be realized with a simple configuration.

  That is, the gas cooling passage 25 is partitioned into a plurality of small passages 25a by the first and second ribs 35 and 36, and the EGR is formed by the gap of the minute interval D1 formed between the first and second ribs 35 and 36. A good cooling efficiency of the EGR gas can be realized by moving a part of the gas between the small passages 25a at a high flow rate. In this case, by adopting a configuration in which the first and second ribs 35 and 36 are protruded from the gas cooling passage 25, gas cooling can be achieved with a simple configuration without using another member such as a corrugated fin provided with a slit. While the passage 25 is divided into a plurality of small passages 25a, a part of the EGR gas can be moved between the small passages 25a.

  In addition, the distance D2 between the first and second ribs 35 and 36 in the upstream end region and the downstream end region of the gas cooling passage 25 is relatively wider than the intermediate region interval (small interval D1). Accordingly, even when the first and second ribs 35 and 36 are provided, it is possible to suitably suppress an increase in flow path resistance when the EGR gas flows into and out of the gas cooling passage 25.

  Further, by providing a third rib 37 protruding from the inner wall portion of the gas cooling passage 25 at the side portion in the arrangement direction of the first and second ribs 35 and 36, movement of EGR gas between the small passages 25a can be performed. It can promote more suitably.

  Further, the gas cooling passage 25 is divided and formed by the first passage member 27 made of a cast product having the first rib 35 and the second passage member 28 made of a cast product having the second rib 36. Thus, the interval between the first and second ribs 35 and 26 can be managed with high processing accuracy, and the minute interval D1 of about 1 mm can be set over a wide range. At that time, by forming the first passage member 27 integrally with the water transfer passage 15, the number of parts can be reduced and the EGR cooler 22 can be further simplified.

  In addition, this invention is not limited to each embodiment described above, A various deformation | transformation and change are possible, and they are also in the technical scope of this invention.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Cylinder head 2a ... Intake port 2b ... Exhaust port 3 ... Cylinder block 3a ... Water jacket 4 ... Intake manifold 5 ... Intake pipe 5a ... Air chamber 6 ... Exhaust manifold 7 ... Exhaust pipe 8 ... Exhaust purification catalyst 9 ... Muffler 15 ... Water passage (cooling water passage)
15a ... Communication port 16 ... Main circulation passage 17 ... Secondary circulation passage 18 ... Bottom bypass passage 20 ... EGR device 21 ... EGR passage 21a ... Upstream passage 21b ... Downstream passage 22 ... EGR cooler 23 ... EGR valve 25 ... Gas cooling passage 25a ... Small passage 27 ... First passage member 28 ... Second passage member 30 ... Upstream side connection pipe 31 ... Downstream side connection pipe 32 ... Valve holding hole 35 ... First rib 36 ... Second rib 37 ... First 3 ribs D1 Interval of midway region (minute interval)
D2: Distance between upstream end region and downstream end region

Claims (4)

A gas cooling passage integrally provided in the cooling water passage, the upstream side communicating with the exhaust system and the downstream side communicating with the intake system;
A plurality of first ribs protruding from an inner wall portion of the gas cooling passage and extending from the upstream side to the downstream side of the gas cooling passage;
A plurality of second ribs projecting from the inner wall portion of the gas cooling passage and extending from the upstream side to the downstream side of the gas cooling passage so as to face the first rib with a slight gap therebetween. An engine EGR cooler characterized by   The interval between the first rib and the second rib facing each other is such that the interval between the upstream end region and the lower end region of the gas cooling passage is relatively larger than the interval between these intermediate regions. 2. The engine EGR cooler according to claim 1, wherein the EGR cooler is widely set.   3. The engine EGR cooler according to claim 1, further comprising a third rib protruding from an inner wall portion of the gas cooling passage at a side portion in the arrangement direction of the first and second ribs. 4. . The gas cooling passage is recessed in an outer wall portion of the cooling water passage made of a cast product, and has a first passage member having the first rib;
4. The cooling water passage according to claim 1, wherein the cooling water passage is formed of a separate casting and is joined to a second passage member having the second rib. The engine EGR cooler according to any one of the preceding claims.

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